text: // SPDX-License-Identifier: GPL-1.0+
  /*
   * Device driver for Microgate SyncLink GT serial adapters.
   *
   * written by Paul Fulghum for Microgate Corporation
   * paulkf@microgate.com
   *
   * Microgate and SyncLink are trademarks of Microgate Corporation
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  /*
   * DEBUG OUTPUT DEFINITIONS
   *
   * uncomment lines below to enable specific types of debug output
   *
   * DBGINFO   information - most verbose output
   * DBGERR    serious errors
   * DBGBH     bottom half service routine debugging
   * DBGISR    interrupt service routine debugging
   * DBGDATA   output receive and transmit data
   * DBGTBUF   output transmit DMA buffers and registers
   * DBGRBUF   output receive DMA buffers and registers
   */
  
  #define DBGINFO(fmt) if (debug_level >= DEBUG_LEVEL_INFO) printk fmt
  #define DBGERR(fmt) if (debug_level >= DEBUG_LEVEL_ERROR) printk fmt
  #define DBGBH(fmt) if (debug_level >= DEBUG_LEVEL_BH) printk fmt
  #define DBGISR(fmt) if (debug_level >= DEBUG_LEVEL_ISR) printk fmt
  #define DBGDATA(info, buf, size, label) if (debug_level >= DEBUG_LEVEL_DATA) trace_block((info), (buf), (size), (label))
  /*#define DBGTBUF(info) dump_tbufs(info)*/
  /*#define DBGRBUF(info) dump_rbufs(info)*/
  
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/signal.h>
  #include <linux/sched.h>
  #include <linux/timer.h>
  #include <linux/interrupt.h>
  #include <linux/pci.h>
  #include <linux/tty.h>
  #include <linux/tty_flip.h>
  #include <linux/serial.h>
  #include <linux/major.h>
  #include <linux/string.h>
  #include <linux/fcntl.h>
  #include <linux/ptrace.h>
  #include <linux/ioport.h>
  #include <linux/mm.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
  #include <linux/netdevice.h>
  #include <linux/vmalloc.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  #include <linux/ioctl.h>
  #include <linux/termios.h>
  #include <linux/bitops.h>
  #include <linux/workqueue.h>
  #include <linux/hdlc.h>
  #include <linux/synclink.h>
  
  #include <asm/io.h>
  #include <asm/irq.h>
  #include <asm/dma.h>
  #include <asm/types.h>
  #include <linux/uaccess.h>
  
  #if defined(CONFIG_HDLC) || (defined(CONFIG_HDLC_MODULE) && defined(CONFIG_SYNCLINK_GT_MODULE))
  #define SYNCLINK_GENERIC_HDLC 1
  #else
  #define SYNCLINK_GENERIC_HDLC 0
  #endif
  
  /*
   * module identification
   */
  static char *driver_name     = "SyncLink GT";
  static char *slgt_driver_name = "synclink_gt";
  static char *tty_dev_prefix  = "ttySLG";
  MODULE_LICENSE("GPL");
  #define MGSL_MAGIC 0x5401
  #define MAX_DEVICES 32
  
  static const struct pci_device_id pci_table[] = {
  	{PCI_VENDOR_ID_MICROGATE, SYNCLINK_GT_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
  	{PCI_VENDOR_ID_MICROGATE, SYNCLINK_GT2_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
  	{PCI_VENDOR_ID_MICROGATE, SYNCLINK_GT4_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
  	{PCI_VENDOR_ID_MICROGATE, SYNCLINK_AC_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
  	{0,}, /* terminate list */
  };
  MODULE_DEVICE_TABLE(pci, pci_table);
  
  static int  init_one(struct pci_dev *dev,const struct pci_device_id *ent);
  static void remove_one(struct pci_dev *dev);
  static struct pci_driver pci_driver = {
  	.name		= "synclink_gt",
  	.id_table	= pci_table,
  	.probe		= init_one,
  	.remove		= remove_one,
  };
  
  static bool pci_registered;
  
  /*
   * module configuration and status
   */
  static struct slgt_info *slgt_device_list;
  static int slgt_device_count;
  
  static int ttymajor;
  static int debug_level;
  static int maxframe[MAX_DEVICES];
  
  module_param(ttymajor, int, 0);
  module_param(debug_level, int, 0);
  module_param_array(maxframe, int, NULL, 0);
  
  MODULE_PARM_DESC(ttymajor, "TTY major device number override: 0=auto assigned");
  MODULE_PARM_DESC(debug_level, "Debug syslog output: 0=disabled, 1 to 5=increasing detail");
  MODULE_PARM_DESC(maxframe, "Maximum frame size used by device (4096 to 65535)");
  
  /*
   * tty support and callbacks
   */
  static struct tty_driver *serial_driver;
  
  static int  open(struct tty_struct *tty, struct file * filp);
  static void close(struct tty_struct *tty, struct file * filp);
  static void hangup(struct tty_struct *tty);
  static void set_termios(struct tty_struct *tty, struct ktermios *old_termios);
  
  static int  write(struct tty_struct *tty, const unsigned char *buf, int count);
  static int put_char(struct tty_struct *tty, unsigned char ch);
  static void send_xchar(struct tty_struct *tty, char ch);
  static void wait_until_sent(struct tty_struct *tty, int timeout);
  static int  write_room(struct tty_struct *tty);
  static void flush_chars(struct tty_struct *tty);
  static void flush_buffer(struct tty_struct *tty);
  static void tx_hold(struct tty_struct *tty);
  static void tx_release(struct tty_struct *tty);
  
  static int  ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
  static int  chars_in_buffer(struct tty_struct *tty);
  static void throttle(struct tty_struct * tty);
  static void unthrottle(struct tty_struct * tty);
  static int set_break(struct tty_struct *tty, int break_state);
  
  /*
   * generic HDLC support and callbacks
   */
  #if SYNCLINK_GENERIC_HDLC
  #define dev_to_port(D) (dev_to_hdlc(D)->priv)
  static void hdlcdev_tx_done(struct slgt_info *info);
  static void hdlcdev_rx(struct slgt_info *info, char *buf, int size);
  static int  hdlcdev_init(struct slgt_info *info);
  static void hdlcdev_exit(struct slgt_info *info);
  #endif
  
  
  /*
   * device specific structures, macros and functions
   */
  
  #define SLGT_MAX_PORTS 4
  #define SLGT_REG_SIZE  256
  
  /*
   * conditional wait facility
   */
  struct cond_wait {
  	struct cond_wait *next;
  	wait_queue_head_t q;
  	wait_queue_entry_t wait;
  	unsigned int data;
  };
  static void init_cond_wait(struct cond_wait *w, unsigned int data);
  static void add_cond_wait(struct cond_wait **head, struct cond_wait *w);
  static void remove_cond_wait(struct cond_wait **head, struct cond_wait *w);
  static void flush_cond_wait(struct cond_wait **head);
  
  /*
   * DMA buffer descriptor and access macros
   */
  struct slgt_desc
  {
  	__le16 count;
  	__le16 status;
  	__le32 pbuf;  /* physical address of data buffer */
  	__le32 next;  /* physical address of next descriptor */
  
  	/* driver book keeping */
  	char *buf;          /* virtual  address of data buffer */
      	unsigned int pdesc; /* physical address of this descriptor */
  	dma_addr_t buf_dma_addr;
  	unsigned short buf_count;
  };
  
  #define set_desc_buffer(a,b) (a).pbuf = cpu_to_le32((unsigned int)(b))
  #define set_desc_next(a,b) (a).next   = cpu_to_le32((unsigned int)(b))
  #define set_desc_count(a,b)(a).count  = cpu_to_le16((unsigned short)(b))
  #define set_desc_eof(a,b)  (a).status = cpu_to_le16((b) ? (le16_to_cpu((a).status) | BIT0) : (le16_to_cpu((a).status) & ~BIT0))
  #define set_desc_status(a, b) (a).status = cpu_to_le16((unsigned short)(b))
  #define desc_count(a)      (le16_to_cpu((a).count))
  #define desc_status(a)     (le16_to_cpu((a).status))
  #define desc_complete(a)   (le16_to_cpu((a).status) & BIT15)
  #define desc_eof(a)        (le16_to_cpu((a).status) & BIT2)
  #define desc_crc_error(a)  (le16_to_cpu((a).status) & BIT1)
  #define desc_abort(a)      (le16_to_cpu((a).status) & BIT0)
  #define desc_residue(a)    ((le16_to_cpu((a).status) & 0x38) >> 3)
  
  struct _input_signal_events {
  	int ri_up;
  	int ri_down;
  	int dsr_up;
  	int dsr_down;
  	int dcd_up;
  	int dcd_down;
  	int cts_up;
  	int cts_down;
  };
  
  /*
   * device instance data structure
   */
  struct slgt_info {
  	void *if_ptr;		/* General purpose pointer (used by SPPP) */
  	struct tty_port port;
  
  	struct slgt_info *next_device;	/* device list link */
  
  	int magic;
  
  	char device_name[25];
  	struct pci_dev *pdev;
  
  	int port_count;  /* count of ports on adapter */
  	int adapter_num; /* adapter instance number */
  	int port_num;    /* port instance number */
  
  	/* array of pointers to port contexts on this adapter */
  	struct slgt_info *port_array[SLGT_MAX_PORTS];
  
  	int			line;		/* tty line instance number */
  
  	struct mgsl_icount	icount;
  
  	int			timeout;
  	int			x_char;		/* xon/xoff character */
  	unsigned int		read_status_mask;
  	unsigned int 		ignore_status_mask;
  
  	wait_queue_head_t	status_event_wait_q;
  	wait_queue_head_t	event_wait_q;
  	struct timer_list	tx_timer;
  	struct timer_list	rx_timer;
  
  	unsigned int            gpio_present;
  	struct cond_wait        *gpio_wait_q;
  
  	spinlock_t lock;	/* spinlock for synchronizing with ISR */
  
  	struct work_struct task;
  	u32 pending_bh;
  	bool bh_requested;
  	bool bh_running;
  
  	int isr_overflow;
  	bool irq_requested;	/* true if IRQ requested */
  	bool irq_occurred;	/* for diagnostics use */
  
  	/* device configuration */
  
  	unsigned int bus_type;
  	unsigned int irq_level;
  	unsigned long irq_flags;
  
  	unsigned char __iomem * reg_addr;  /* memory mapped registers address */
  	u32 phys_reg_addr;
  	bool reg_addr_requested;
  
  	MGSL_PARAMS params;       /* communications parameters */
  	u32 idle_mode;
  	u32 max_frame_size;       /* as set by device config */
  
  	unsigned int rbuf_fill_level;
  	unsigned int rx_pio;
  	unsigned int if_mode;
  	unsigned int base_clock;
  	unsigned int xsync;
  	unsigned int xctrl;
  
  	/* device status */
  
  	bool rx_enabled;
  	bool rx_restart;
  
  	bool tx_enabled;
  	bool tx_active;
  
  	unsigned char signals;    /* serial signal states */
  	int init_error;  /* initialization error */
  
  	unsigned char *tx_buf;
  	int tx_count;
  
  	char *flag_buf;
  	bool drop_rts_on_tx_done;
  	struct	_input_signal_events	input_signal_events;
  
  	int dcd_chkcount;	/* check counts to prevent */
  	int cts_chkcount;	/* too many IRQs if a signal */
  	int dsr_chkcount;	/* is floating */
  	int ri_chkcount;
  
  	char *bufs;		/* virtual address of DMA buffer lists */
  	dma_addr_t bufs_dma_addr; /* physical address of buffer descriptors */
  
  	unsigned int rbuf_count;
  	struct slgt_desc *rbufs;
  	unsigned int rbuf_current;
  	unsigned int rbuf_index;
  	unsigned int rbuf_fill_index;
  	unsigned short rbuf_fill_count;
  
  	unsigned int tbuf_count;
  	struct slgt_desc *tbufs;
  	unsigned int tbuf_current;
  	unsigned int tbuf_start;
  
  	unsigned char *tmp_rbuf;
  	unsigned int tmp_rbuf_count;
  
  	/* SPPP/Cisco HDLC device parts */
  
  	int netcount;
  	spinlock_t netlock;
  #if SYNCLINK_GENERIC_HDLC
  	struct net_device *netdev;
  #endif
  
  };
  
  static MGSL_PARAMS default_params = {
  	.mode            = MGSL_MODE_HDLC,
  	.loopback        = 0,
  	.flags           = HDLC_FLAG_UNDERRUN_ABORT15,
  	.encoding        = HDLC_ENCODING_NRZI_SPACE,
  	.clock_speed     = 0,
  	.addr_filter     = 0xff,
  	.crc_type        = HDLC_CRC_16_CCITT,
  	.preamble_length = HDLC_PREAMBLE_LENGTH_8BITS,
  	.preamble        = HDLC_PREAMBLE_PATTERN_NONE,
  	.data_rate       = 9600,
  	.data_bits       = 8,
  	.stop_bits       = 1,
  	.parity          = ASYNC_PARITY_NONE
  };
  
  
  #define BH_RECEIVE  1
  #define BH_TRANSMIT 2
  #define BH_STATUS   4
  #define IO_PIN_SHUTDOWN_LIMIT 100
  
  #define DMABUFSIZE 256
  #define DESC_LIST_SIZE 4096
  
  #define MASK_PARITY  BIT1
  #define MASK_FRAMING BIT0
  #define MASK_BREAK   BIT14
  #define MASK_OVERRUN BIT4
  
  #define GSR   0x00 /* global status */
  #define JCR   0x04 /* JTAG control */
  #define IODR  0x08 /* GPIO direction */
  #define IOER  0x0c /* GPIO interrupt enable */
  #define IOVR  0x10 /* GPIO value */
  #define IOSR  0x14 /* GPIO interrupt status */
  #define TDR   0x80 /* tx data */
  #define RDR   0x80 /* rx data */
  #define TCR   0x82 /* tx control */
  #define TIR   0x84 /* tx idle */
  #define TPR   0x85 /* tx preamble */
  #define RCR   0x86 /* rx control */
  #define VCR   0x88 /* V.24 control */
  #define CCR   0x89 /* clock control */
  #define BDR   0x8a /* baud divisor */
  #define SCR   0x8c /* serial control */
  #define SSR   0x8e /* serial status */
  #define RDCSR 0x90 /* rx DMA control/status */
  #define TDCSR 0x94 /* tx DMA control/status */
  #define RDDAR 0x98 /* rx DMA descriptor address */
  #define TDDAR 0x9c /* tx DMA descriptor address */
  #define XSR   0x40 /* extended sync pattern */
  #define XCR   0x44 /* extended control */
  
  #define RXIDLE      BIT14
  #define RXBREAK     BIT14
  #define IRQ_TXDATA  BIT13
  #define IRQ_TXIDLE  BIT12
  #define IRQ_TXUNDER BIT11 /* HDLC */
  #define IRQ_RXDATA  BIT10
  #define IRQ_RXIDLE  BIT9  /* HDLC */
  #define IRQ_RXBREAK BIT9  /* async */
  #define IRQ_RXOVER  BIT8
  #define IRQ_DSR     BIT7
  #define IRQ_CTS     BIT6
  #define IRQ_DCD     BIT5
  #define IRQ_RI      BIT4
  #define IRQ_ALL     0x3ff0
  #define IRQ_MASTER  BIT0
  
  #define slgt_irq_on(info, mask) \
  	wr_reg16((info), SCR, (unsigned short)(rd_reg16((info), SCR) | (mask)))
  #define slgt_irq_off(info, mask) \
  	wr_reg16((info), SCR, (unsigned short)(rd_reg16((info), SCR) & ~(mask)))
  
  static __u8  rd_reg8(struct slgt_info *info, unsigned int addr);
  static void  wr_reg8(struct slgt_info *info, unsigned int addr, __u8 value);
  static __u16 rd_reg16(struct slgt_info *info, unsigned int addr);
  static void  wr_reg16(struct slgt_info *info, unsigned int addr, __u16 value);
  static __u32 rd_reg32(struct slgt_info *info, unsigned int addr);
  static void  wr_reg32(struct slgt_info *info, unsigned int addr, __u32 value);
  
  static void  msc_set_vcr(struct slgt_info *info);
  
  static int  startup(struct slgt_info *info);
  static int  block_til_ready(struct tty_struct *tty, struct file * filp,struct slgt_info *info);
  static void shutdown(struct slgt_info *info);
  static void program_hw(struct slgt_info *info);
  static void change_params(struct slgt_info *info);
  
  static int  register_test(struct slgt_info *info);
  static int  irq_test(struct slgt_info *info);
  static int  loopback_test(struct slgt_info *info);
  static int  adapter_test(struct slgt_info *info);
  
  static void reset_adapter(struct slgt_info *info);
  static void reset_port(struct slgt_info *info);
  static void async_mode(struct slgt_info *info);
  static void sync_mode(struct slgt_info *info);
  
  static void rx_stop(struct slgt_info *info);
  static void rx_start(struct slgt_info *info);
  static void reset_rbufs(struct slgt_info *info);
  static void free_rbufs(struct slgt_info *info, unsigned int first, unsigned int last);
  static void rdma_reset(struct slgt_info *info);
  static bool rx_get_frame(struct slgt_info *info);
  static bool rx_get_buf(struct slgt_info *info);
  
  static void tx_start(struct slgt_info *info);
  static void tx_stop(struct slgt_info *info);
  static void tx_set_idle(struct slgt_info *info);
  static unsigned int free_tbuf_count(struct slgt_info *info);
  static unsigned int tbuf_bytes(struct slgt_info *info);
  static void reset_tbufs(struct slgt_info *info);
  static void tdma_reset(struct slgt_info *info);
  static bool tx_load(struct slgt_info *info, const char *buf, unsigned int count);
  
  static void get_signals(struct slgt_info *info);
  static void set_signals(struct slgt_info *info);
  static void enable_loopback(struct slgt_info *info);
  static void set_rate(struct slgt_info *info, u32 data_rate);
  
  static int  bh_action(struct slgt_info *info);
  static void bh_handler(struct work_struct *work);
  static void bh_transmit(struct slgt_info *info);
  static void isr_serial(struct slgt_info *info);
  static void isr_rdma(struct slgt_info *info);
  static void isr_txeom(struct slgt_info *info, unsigned short status);
  static void isr_tdma(struct slgt_info *info);
  
  static int  alloc_dma_bufs(struct slgt_info *info);
  static void free_dma_bufs(struct slgt_info *info);
  static int  alloc_desc(struct slgt_info *info);
  static void free_desc(struct slgt_info *info);
  static int  alloc_bufs(struct slgt_info *info, struct slgt_desc *bufs, int count);
  static void free_bufs(struct slgt_info *info, struct slgt_desc *bufs, int count);
  
  static int  alloc_tmp_rbuf(struct slgt_info *info);
  static void free_tmp_rbuf(struct slgt_info *info);
  
  static void tx_timeout(struct timer_list *t);
  static void rx_timeout(struct timer_list *t);
  
  /*
   * ioctl handlers
   */
  static int  get_stats(struct slgt_info *info, struct mgsl_icount __user *user_icount);
  static int  get_params(struct slgt_info *info, MGSL_PARAMS __user *params);
  static int  set_params(struct slgt_info *info, MGSL_PARAMS __user *params);
  static int  get_txidle(struct slgt_info *info, int __user *idle_mode);
  static int  set_txidle(struct slgt_info *info, int idle_mode);
  static int  tx_enable(struct slgt_info *info, int enable);
  static int  tx_abort(struct slgt_info *info);
  static int  rx_enable(struct slgt_info *info, int enable);
  static int  modem_input_wait(struct slgt_info *info,int arg);
  static int  wait_mgsl_event(struct slgt_info *info, int __user *mask_ptr);
  static int  tiocmget(struct tty_struct *tty);
  static int  tiocmset(struct tty_struct *tty,
  				unsigned int set, unsigned int clear);
  static int set_break(struct tty_struct *tty, int break_state);
  static int  get_interface(struct slgt_info *info, int __user *if_mode);
  static int  set_interface(struct slgt_info *info, int if_mode);
  static int  set_gpio(struct slgt_info *info, struct gpio_desc __user *gpio);
  static int  get_gpio(struct slgt_info *info, struct gpio_desc __user *gpio);
  static int  wait_gpio(struct slgt_info *info, struct gpio_desc __user *gpio);
  static int  get_xsync(struct slgt_info *info, int __user *if_mode);
  static int  set_xsync(struct slgt_info *info, int if_mode);
  static int  get_xctrl(struct slgt_info *info, int __user *if_mode);
  static int  set_xctrl(struct slgt_info *info, int if_mode);
  
  /*
   * driver functions
   */
  static void add_device(struct slgt_info *info);
  static void device_init(int adapter_num, struct pci_dev *pdev);
  static int  claim_resources(struct slgt_info *info);
  static void release_resources(struct slgt_info *info);
  
  /*
   * DEBUG OUTPUT CODE
   */
  #ifndef DBGINFO
  #define DBGINFO(fmt)
  #endif
  #ifndef DBGERR
  #define DBGERR(fmt)
  #endif
  #ifndef DBGBH
  #define DBGBH(fmt)
  #endif
  #ifndef DBGISR
  #define DBGISR(fmt)
  #endif
  
  #ifdef DBGDATA
  static void trace_block(struct slgt_info *info, const char *data, int count, const char *label)
  {
  	int i;
  	int linecount;
  	printk("%s %s data:\n",info->device_name, label);
  	while(count) {
  		linecount = (count > 16) ? 16 : count;
  		for(i=0; i < linecount; i++)
  			printk("%02X ",(unsigned char)data[i]);
  		for(;i<17;i++)
  			printk("   ");
  		for(i=0;i<linecount;i++) {
  			if (data[i]>=040 && data[i]<=0176)
  				printk("%c",data[i]);
  			else
  				printk(".");
  		}
  		printk("\n");
  		data  += linecount;
  		count -= linecount;
  	}
  }
  #else
  #define DBGDATA(info, buf, size, label)
  #endif
  
  #ifdef DBGTBUF
  static void dump_tbufs(struct slgt_info *info)
  {
  	int i;
  	printk("tbuf_current=%d\n", info->tbuf_current);
  	for (i=0 ; i < info->tbuf_count ; i++) {
  		printk("%d: count=%04X status=%04X\n",
  			i, le16_to_cpu(info->tbufs[i].count), le16_to_cpu(info->tbufs[i].status));
  	}
  }
  #else
  #define DBGTBUF(info)
  #endif
  
  #ifdef DBGRBUF
  static void dump_rbufs(struct slgt_info *info)
  {
  	int i;
  	printk("rbuf_current=%d\n", info->rbuf_current);
  	for (i=0 ; i < info->rbuf_count ; i++) {
  		printk("%d: count=%04X status=%04X\n",
  			i, le16_to_cpu(info->rbufs[i].count), le16_to_cpu(info->rbufs[i].status));
  	}
  }
  #else
  #define DBGRBUF(info)
  #endif
  
  static inline int sanity_check(struct slgt_info *info, char *devname, const char *name)
  {
  #ifdef SANITY_CHECK
  	if (!info) {
  		printk("null struct slgt_info for (%s) in %s\n", devname, name);
  		return 1;
  	}
  	if (info->magic != MGSL_MAGIC) {
  		printk("bad magic number struct slgt_info (%s) in %s\n", devname, name);
  		return 1;
  	}
  #else
  	if (!info)
  		return 1;
  #endif
  	return 0;
  }
  
  /**
   * line discipline callback wrappers
   *
   * The wrappers maintain line discipline references
   * while calling into the line discipline.
   *
   * ldisc_receive_buf  - pass receive data to line discipline
   */
  static void ldisc_receive_buf(struct tty_struct *tty,
  			      const __u8 *data, char *flags, int count)
  {
  	struct tty_ldisc *ld;
  	if (!tty)
  		return;
  	ld = tty_ldisc_ref(tty);
  	if (ld) {
  		if (ld->ops->receive_buf)
  			ld->ops->receive_buf(tty, data, flags, count);
  		tty_ldisc_deref(ld);
  	}
  }
  
  /* tty callbacks */
  
  static int open(struct tty_struct *tty, struct file *filp)
  {
  	struct slgt_info *info;
  	int retval, line;
  	unsigned long flags;
  
  	line = tty->index;
  	if (line >= slgt_device_count) {
  		DBGERR(("%s: open with invalid line #%d.\n", driver_name, line));
  		return -ENODEV;
  	}
  
  	info = slgt_device_list;
  	while(info && info->line != line)
  		info = info->next_device;
  	if (sanity_check(info, tty->name, "open"))
  		return -ENODEV;
  	if (info->init_error) {
  		DBGERR(("%s init error=%d\n", info->device_name, info->init_error));
  		return -ENODEV;
  	}
  
  	tty->driver_data = info;
  	info->port.tty = tty;
  
  	DBGINFO(("%s open, old ref count = %d\n", info->device_name, info->port.count));
  
  	mutex_lock(&info->port.mutex);
  	info->port.low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;
  
  	spin_lock_irqsave(&info->netlock, flags);
  	if (info->netcount) {
  		retval = -EBUSY;
  		spin_unlock_irqrestore(&info->netlock, flags);
  		mutex_unlock(&info->port.mutex);
  		goto cleanup;
  	}
  	info->port.count++;
  	spin_unlock_irqrestore(&info->netlock, flags);
  
  	if (info->port.count == 1) {
  		/* 1st open on this device, init hardware */
  		retval = startup(info);
  		if (retval < 0) {
  			mutex_unlock(&info->port.mutex);
  			goto cleanup;
  		}
  	}
  	mutex_unlock(&info->port.mutex);
  	retval = block_til_ready(tty, filp, info);
  	if (retval) {
  		DBGINFO(("%s block_til_ready rc=%d\n", info->device_name, retval));
  		goto cleanup;
  	}
  
  	retval = 0;
  
  cleanup:
  	if (retval) {
  		if (tty->count == 1)
  			info->port.tty = NULL; /* tty layer will release tty struct */
  		if(info->port.count)
  			info->port.count--;
  	}
  
  	DBGINFO(("%s open rc=%d\n", info->device_name, retval));
  	return retval;
  }
  
  static void close(struct tty_struct *tty, struct file *filp)
  {
  	struct slgt_info *info = tty->driver_data;
  
  	if (sanity_check(info, tty->name, "close"))
  		return;
  	DBGINFO(("%s close entry, count=%d\n", info->device_name, info->port.count));
  
  	if (tty_port_close_start(&info->port, tty, filp) == 0)
  		goto cleanup;
  
  	mutex_lock(&info->port.mutex);
  	if (tty_port_initialized(&info->port))
   		wait_until_sent(tty, info->timeout);
  	flush_buffer(tty);
  	tty_ldisc_flush(tty);
  
  	shutdown(info);
  	mutex_unlock(&info->port.mutex);
  
  	tty_port_close_end(&info->port, tty);
  	info->port.tty = NULL;
  cleanup:
  	DBGINFO(("%s close exit, count=%d\n", tty->driver->name, info->port.count));
  }
  
  static void hangup(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "hangup"))
  		return;
  	DBGINFO(("%s hangup\n", info->device_name));
  
  	flush_buffer(tty);
  
  	mutex_lock(&info->port.mutex);
  	shutdown(info);
  
  	spin_lock_irqsave(&info->port.lock, flags);
  	info->port.count = 0;
  	info->port.tty = NULL;
  	spin_unlock_irqrestore(&info->port.lock, flags);
  	tty_port_set_active(&info->port, 0);
  	mutex_unlock(&info->port.mutex);
  
  	wake_up_interruptible(&info->port.open_wait);
  }
  
  static void set_termios(struct tty_struct *tty, struct ktermios *old_termios)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	DBGINFO(("%s set_termios\n", tty->driver->name));
  
  	change_params(info);
  
  	/* Handle transition to B0 status */
  	if ((old_termios->c_cflag & CBAUD) && !C_BAUD(tty)) {
  		info->signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
  		spin_lock_irqsave(&info->lock,flags);
  		set_signals(info);
  		spin_unlock_irqrestore(&info->lock,flags);
  	}
  
  	/* Handle transition away from B0 status */
  	if (!(old_termios->c_cflag & CBAUD) && C_BAUD(tty)) {
  		info->signals |= SerialSignal_DTR;
  		if (!C_CRTSCTS(tty) || !tty_throttled(tty))
  			info->signals |= SerialSignal_RTS;
  		spin_lock_irqsave(&info->lock,flags);
  	 	set_signals(info);
  		spin_unlock_irqrestore(&info->lock,flags);
  	}
  
  	/* Handle turning off CRTSCTS */
  	if ((old_termios->c_cflag & CRTSCTS) && !C_CRTSCTS(tty)) {
  		tty->hw_stopped = 0;
  		tx_release(tty);
  	}
  }
  
  static void update_tx_timer(struct slgt_info *info)
  {
  	/*
  	 * use worst case speed of 1200bps to calculate transmit timeout
  	 * based on data in buffers (tbuf_bytes) and FIFO (128 bytes)
  	 */
  	if (info->params.mode == MGSL_MODE_HDLC) {
  		int timeout  = (tbuf_bytes(info) * 7) + 1000;
  		mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(timeout));
  	}
  }
  
  static int write(struct tty_struct *tty,
  		 const unsigned char *buf, int count)
  {
  	int ret = 0;
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "write"))
  		return -EIO;
  
  	DBGINFO(("%s write count=%d\n", info->device_name, count));
  
  	if (!info->tx_buf || (count > info->max_frame_size))
  		return -EIO;
  
  	if (!count || tty->stopped || tty->hw_stopped)
  		return 0;
  
  	spin_lock_irqsave(&info->lock, flags);
  
  	if (info->tx_count) {
  		/* send accumulated data from send_char() */
  		if (!tx_load(info, info->tx_buf, info->tx_count))
  			goto cleanup;
  		info->tx_count = 0;
  	}
  
  	if (tx_load(info, buf, count))
  		ret = count;
  
  cleanup:
  	spin_unlock_irqrestore(&info->lock, flags);
  	DBGINFO(("%s write rc=%d\n", info->device_name, ret));
  	return ret;
  }
  
  static int put_char(struct tty_struct *tty, unsigned char ch)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  	int ret = 0;
  
  	if (sanity_check(info, tty->name, "put_char"))
  		return 0;
  	DBGINFO(("%s put_char(%d)\n", info->device_name, ch));
  	if (!info->tx_buf)
  		return 0;
  	spin_lock_irqsave(&info->lock,flags);
  	if (info->tx_count < info->max_frame_size) {
  		info->tx_buf[info->tx_count++] = ch;
  		ret = 1;
  	}
  	spin_unlock_irqrestore(&info->lock,flags);
  	return ret;
  }
  
  static void send_xchar(struct tty_struct *tty, char ch)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "send_xchar"))
  		return;
  	DBGINFO(("%s send_xchar(%d)\n", info->device_name, ch));
  	info->x_char = ch;
  	if (ch) {
  		spin_lock_irqsave(&info->lock,flags);
  		if (!info->tx_enabled)
  		 	tx_start(info);
  		spin_unlock_irqrestore(&info->lock,flags);
  	}
  }
  
  static void wait_until_sent(struct tty_struct *tty, int timeout)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long orig_jiffies, char_time;
  
  	if (!info )
  		return;
  	if (sanity_check(info, tty->name, "wait_until_sent"))
  		return;
  	DBGINFO(("%s wait_until_sent entry\n", info->device_name));
  	if (!tty_port_initialized(&info->port))
  		goto exit;
  
  	orig_jiffies = jiffies;
  
  	/* Set check interval to 1/5 of estimated time to
  	 * send a character, and make it at least 1. The check
  	 * interval should also be less than the timeout.
  	 * Note: use tight timings here to satisfy the NIST-PCTS.
  	 */
  
  	if (info->params.data_rate) {
  	       	char_time = info->timeout/(32 * 5);
  		if (!char_time)
  			char_time++;
  	} else
  		char_time = 1;
  
  	if (timeout)
  		char_time = min_t(unsigned long, char_time, timeout);
  
  	while (info->tx_active) {
  		msleep_interruptible(jiffies_to_msecs(char_time));
  		if (signal_pending(current))
  			break;
  		if (timeout && time_after(jiffies, orig_jiffies + timeout))
  			break;
  	}
  exit:
  	DBGINFO(("%s wait_until_sent exit\n", info->device_name));
  }
  
  static int write_room(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	int ret;
  
  	if (sanity_check(info, tty->name, "write_room"))
  		return 0;
  	ret = (info->tx_active) ? 0 : HDLC_MAX_FRAME_SIZE;
  	DBGINFO(("%s write_room=%d\n", info->device_name, ret));
  	return ret;
  }
  
  static void flush_chars(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "flush_chars"))
  		return;
  	DBGINFO(("%s flush_chars entry tx_count=%d\n", info->device_name, info->tx_count));
  
  	if (info->tx_count <= 0 || tty->stopped ||
  	    tty->hw_stopped || !info->tx_buf)
  		return;
  
  	DBGINFO(("%s flush_chars start transmit\n", info->device_name));
  
  	spin_lock_irqsave(&info->lock,flags);
  	if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
  		info->tx_count = 0;
  	spin_unlock_irqrestore(&info->lock,flags);
  }
  
  static void flush_buffer(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "flush_buffer"))
  		return;
  	DBGINFO(("%s flush_buffer\n", info->device_name));
  
  	spin_lock_irqsave(&info->lock, flags);
  	info->tx_count = 0;
  	spin_unlock_irqrestore(&info->lock, flags);
  
  	tty_wakeup(tty);
  }
  
  /*
   * throttle (stop) transmitter
   */
  static void tx_hold(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "tx_hold"))
  		return;
  	DBGINFO(("%s tx_hold\n", info->device_name));
  	spin_lock_irqsave(&info->lock,flags);
  	if (info->tx_enabled && info->params.mode == MGSL_MODE_ASYNC)
  	 	tx_stop(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  }
  
  /*
   * release (start) transmitter
   */
  static void tx_release(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "tx_release"))
  		return;
  	DBGINFO(("%s tx_release\n", info->device_name));
  	spin_lock_irqsave(&info->lock, flags);
  	if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
  		info->tx_count = 0;
  	spin_unlock_irqrestore(&info->lock, flags);
  }
  
  /*
   * Service an IOCTL request
   *
   * Arguments
   *
   * 	tty	pointer to tty instance data
   * 	cmd	IOCTL command code
   * 	arg	command argument/context
   *
   * Return 0 if success, otherwise error code
   */
  static int ioctl(struct tty_struct *tty,
  		 unsigned int cmd, unsigned long arg)
  {
  	struct slgt_info *info = tty->driver_data;
  	void __user *argp = (void __user *)arg;
  	int ret;
  
  	if (sanity_check(info, tty->name, "ioctl"))
  		return -ENODEV;
  	DBGINFO(("%s ioctl() cmd=%08X\n", info->device_name, cmd));
  
  	if (cmd != TIOCMIWAIT) {
  		if (tty_io_error(tty))
  		    return -EIO;
  	}
  
  	switch (cmd) {
  	case MGSL_IOCWAITEVENT:
  		return wait_mgsl_event(info, argp);
  	case TIOCMIWAIT:
  		return modem_input_wait(info,(int)arg);
  	case MGSL_IOCSGPIO:
  		return set_gpio(info, argp);
  	case MGSL_IOCGGPIO:
  		return get_gpio(info, argp);
  	case MGSL_IOCWAITGPIO:
  		return wait_gpio(info, argp);
  	case MGSL_IOCGXSYNC:
  		return get_xsync(info, argp);
  	case MGSL_IOCSXSYNC:
  		return set_xsync(info, (int)arg);
  	case MGSL_IOCGXCTRL:
  		return get_xctrl(info, argp);
  	case MGSL_IOCSXCTRL:
  		return set_xctrl(info, (int)arg);
  	}
  	mutex_lock(&info->port.mutex);
  	switch (cmd) {
  	case MGSL_IOCGPARAMS:
  		ret = get_params(info, argp);
  		break;
  	case MGSL_IOCSPARAMS:
  		ret = set_params(info, argp);
  		break;
  	case MGSL_IOCGTXIDLE:
  		ret = get_txidle(info, argp);
  		break;
  	case MGSL_IOCSTXIDLE:
  		ret = set_txidle(info, (int)arg);
  		break;
  	case MGSL_IOCTXENABLE:
  		ret = tx_enable(info, (int)arg);
  		break;
  	case MGSL_IOCRXENABLE:
  		ret = rx_enable(info, (int)arg);
  		break;
  	case MGSL_IOCTXABORT:
  		ret = tx_abort(info);
  		break;
  	case MGSL_IOCGSTATS:
  		ret = get_stats(info, argp);
  		break;
  	case MGSL_IOCGIF:
  		ret = get_interface(info, argp);
  		break;
  	case MGSL_IOCSIF:
  		ret = set_interface(info,(int)arg);
  		break;
  	default:
  		ret = -ENOIOCTLCMD;
  	}
  	mutex_unlock(&info->port.mutex);
  	return ret;
  }
  
  static int get_icount(struct tty_struct *tty,
  				struct serial_icounter_struct *icount)
  
  {
  	struct slgt_info *info = tty->driver_data;
  	struct mgsl_icount cnow;	/* kernel counter temps */
  	unsigned long flags;
  
  	spin_lock_irqsave(&info->lock,flags);
  	cnow = info->icount;
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	icount->cts = cnow.cts;
  	icount->dsr = cnow.dsr;
  	icount->rng = cnow.rng;
  	icount->dcd = cnow.dcd;
  	icount->rx = cnow.rx;
  	icount->tx = cnow.tx;
  	icount->frame = cnow.frame;
  	icount->overrun = cnow.overrun;
  	icount->parity = cnow.parity;
  	icount->brk = cnow.brk;
  	icount->buf_overrun = cnow.buf_overrun;
  
  	return 0;
  }
  
  /*
   * support for 32 bit ioctl calls on 64 bit systems
   */
  #ifdef CONFIG_COMPAT
  static long get_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *user_params)
  {
  	struct MGSL_PARAMS32 tmp_params;
  
  	DBGINFO(("%s get_params32\n", info->device_name));
  	memset(&tmp_params, 0, sizeof(tmp_params));
  	tmp_params.mode            = (compat_ulong_t)info->params.mode;
  	tmp_params.loopback        = info->params.loopback;
  	tmp_params.flags           = info->params.flags;
  	tmp_params.encoding        = info->params.encoding;
  	tmp_params.clock_speed     = (compat_ulong_t)info->params.clock_speed;
  	tmp_params.addr_filter     = info->params.addr_filter;
  	tmp_params.crc_type        = info->params.crc_type;
  	tmp_params.preamble_length = info->params.preamble_length;
  	tmp_params.preamble        = info->params.preamble;
  	tmp_params.data_rate       = (compat_ulong_t)info->params.data_rate;
  	tmp_params.data_bits       = info->params.data_bits;
  	tmp_params.stop_bits       = info->params.stop_bits;
  	tmp_params.parity          = info->params.parity;
  	if (copy_to_user(user_params, &tmp_params, sizeof(struct MGSL_PARAMS32)))
  		return -EFAULT;
  	return 0;
  }
  
  static long set_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *new_params)
  {
  	struct MGSL_PARAMS32 tmp_params;
  
  	DBGINFO(("%s set_params32\n", info->device_name));
  	if (copy_from_user(&tmp_params, new_params, sizeof(struct MGSL_PARAMS32)))
  		return -EFAULT;
  
  	spin_lock(&info->lock);
  	if (tmp_params.mode == MGSL_MODE_BASE_CLOCK) {
  		info->base_clock = tmp_params.clock_speed;
  	} else {
  		info->params.mode            = tmp_params.mode;
  		info->params.loopback        = tmp_params.loopback;
  		info->params.flags           = tmp_params.flags;
  		info->params.encoding        = tmp_params.encoding;
  		info->params.clock_speed     = tmp_params.clock_speed;
  		info->params.addr_filter     = tmp_params.addr_filter;
  		info->params.crc_type        = tmp_params.crc_type;
  		info->params.preamble_length = tmp_params.preamble_length;
  		info->params.preamble        = tmp_params.preamble;
  		info->params.data_rate       = tmp_params.data_rate;
  		info->params.data_bits       = tmp_params.data_bits;
  		info->params.stop_bits       = tmp_params.stop_bits;
  		info->params.parity          = tmp_params.parity;
  	}
  	spin_unlock(&info->lock);
  
  	program_hw(info);
  
  	return 0;
  }
  
  static long slgt_compat_ioctl(struct tty_struct *tty,
  			 unsigned int cmd, unsigned long arg)
  {
  	struct slgt_info *info = tty->driver_data;
  	int rc;
  
  	if (sanity_check(info, tty->name, "compat_ioctl"))
  		return -ENODEV;
  	DBGINFO(("%s compat_ioctl() cmd=%08X\n", info->device_name, cmd));
  
  	switch (cmd) {
  	case MGSL_IOCSPARAMS32:
  		rc = set_params32(info, compat_ptr(arg));
  		break;
  
  	case MGSL_IOCGPARAMS32:
  		rc = get_params32(info, compat_ptr(arg));
  		break;
  
  	case MGSL_IOCGPARAMS:
  	case MGSL_IOCSPARAMS:
  	case MGSL_IOCGTXIDLE:
  	case MGSL_IOCGSTATS:
  	case MGSL_IOCWAITEVENT:
  	case MGSL_IOCGIF:
  	case MGSL_IOCSGPIO:
  	case MGSL_IOCGGPIO:
  	case MGSL_IOCWAITGPIO:
  	case MGSL_IOCGXSYNC:
  	case MGSL_IOCGXCTRL:
  		rc = ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
  		break;
  	default:
  		rc = ioctl(tty, cmd, arg);
  	}
  	DBGINFO(("%s compat_ioctl() cmd=%08X rc=%d\n", info->device_name, cmd, rc));
  	return rc;
  }
  #else
  #define slgt_compat_ioctl NULL
  #endif /* ifdef CONFIG_COMPAT */
  
  /*
   * proc fs support
   */
  static inline void line_info(struct seq_file *m, struct slgt_info *info)
  {
  	char stat_buf[30];
  	unsigned long flags;
  
  	seq_printf(m, "%s: IO=%08X IRQ=%d MaxFrameSize=%u\n",
  		      info->device_name, info->phys_reg_addr,
  		      info->irq_level, info->max_frame_size);
  
  	/* output current serial signal states */
  	spin_lock_irqsave(&info->lock,flags);
  	get_signals(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	stat_buf[0] = 0;
  	stat_buf[1] = 0;
  	if (info->signals & SerialSignal_RTS)
  		strcat(stat_buf, "|RTS");
  	if (info->signals & SerialSignal_CTS)
  		strcat(stat_buf, "|CTS");
  	if (info->signals & SerialSignal_DTR)
  		strcat(stat_buf, "|DTR");
  	if (info->signals & SerialSignal_DSR)
  		strcat(stat_buf, "|DSR");
  	if (info->signals & SerialSignal_DCD)
  		strcat(stat_buf, "|CD");
  	if (info->signals & SerialSignal_RI)
  		strcat(stat_buf, "|RI");
  
  	if (info->params.mode != MGSL_MODE_ASYNC) {
  		seq_printf(m, "\tHDLC txok:%d rxok:%d",
  			       info->icount.txok, info->icount.rxok);
  		if (info->icount.txunder)
  			seq_printf(m, " txunder:%d", info->icount.txunder);
  		if (info->icount.txabort)
  			seq_printf(m, " txabort:%d", info->icount.txabort);
  		if (info->icount.rxshort)
  			seq_printf(m, " rxshort:%d", info->icount.rxshort);
  		if (info->icount.rxlong)
  			seq_printf(m, " rxlong:%d", info->icount.rxlong);
  		if (info->icount.rxover)
  			seq_printf(m, " rxover:%d", info->icount.rxover);
  		if (info->icount.rxcrc)
  			seq_printf(m, " rxcrc:%d", info->icount.rxcrc);
  	} else {
  		seq_printf(m, "\tASYNC tx:%d rx:%d",
  			       info->icount.tx, info->icount.rx);
  		if (info->icount.frame)
  			seq_printf(m, " fe:%d", info->icount.frame);
  		if (info->icount.parity)
  			seq_printf(m, " pe:%d", info->icount.parity);
  		if (info->icount.brk)
  			seq_printf(m, " brk:%d", info->icount.brk);
  		if (info->icount.overrun)
  			seq_printf(m, " oe:%d", info->icount.overrun);
  	}
  
  	/* Append serial signal status to end */
  	seq_printf(m, " %s\n", stat_buf+1);
  
  	seq_printf(m, "\ttxactive=%d bh_req=%d bh_run=%d pending_bh=%x\n",
  		       info->tx_active,info->bh_requested,info->bh_running,
  		       info->pending_bh);
  }
  
  /* Called to print information about devices
   */
  static int synclink_gt_proc_show(struct seq_file *m, void *v)
  {
  	struct slgt_info *info;
  
  	seq_puts(m, "synclink_gt driver\n");
  
  	info = slgt_device_list;
  	while( info ) {
  		line_info(m, info);
  		info = info->next_device;
  	}
  	return 0;
  }
  
  /*
   * return count of bytes in transmit buffer
   */
  static int chars_in_buffer(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	int count;
  	if (sanity_check(info, tty->name, "chars_in_buffer"))
  		return 0;
  	count = tbuf_bytes(info);
  	DBGINFO(("%s chars_in_buffer()=%d\n", info->device_name, count));
  	return count;
  }
  
  /*
   * signal remote device to throttle send data (our receive data)
   */
  static void throttle(struct tty_struct * tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "throttle"))
  		return;
  	DBGINFO(("%s throttle\n", info->device_name));
  	if (I_IXOFF(tty))
  		send_xchar(tty, STOP_CHAR(tty));
  	if (C_CRTSCTS(tty)) {
  		spin_lock_irqsave(&info->lock,flags);
  		info->signals &= ~SerialSignal_RTS;
  		set_signals(info);
  		spin_unlock_irqrestore(&info->lock,flags);
  	}
  }
  
  /*
   * signal remote device to stop throttling send data (our receive data)
   */
  static void unthrottle(struct tty_struct * tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "unthrottle"))
  		return;
  	DBGINFO(("%s unthrottle\n", info->device_name));
  	if (I_IXOFF(tty)) {
  		if (info->x_char)
  			info->x_char = 0;
  		else
  			send_xchar(tty, START_CHAR(tty));
  	}
  	if (C_CRTSCTS(tty)) {
  		spin_lock_irqsave(&info->lock,flags);
  		info->signals |= SerialSignal_RTS;
  		set_signals(info);
  		spin_unlock_irqrestore(&info->lock,flags);
  	}
  }
  
  /*
   * set or clear transmit break condition
   * break_state	-1=set break condition, 0=clear
   */
  static int set_break(struct tty_struct *tty, int break_state)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned short value;
  	unsigned long flags;
  
  	if (sanity_check(info, tty->name, "set_break"))
  		return -EINVAL;
  	DBGINFO(("%s set_break(%d)\n", info->device_name, break_state));
  
  	spin_lock_irqsave(&info->lock,flags);
  	value = rd_reg16(info, TCR);
   	if (break_state == -1)
  		value |= BIT6;
  	else
  		value &= ~BIT6;
  	wr_reg16(info, TCR, value);
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  #if SYNCLINK_GENERIC_HDLC
  
  /**
   * called by generic HDLC layer when protocol selected (PPP, frame relay, etc.)
   * set encoding and frame check sequence (FCS) options
   *
   * dev       pointer to network device structure
   * encoding  serial encoding setting
   * parity    FCS setting
   *
   * returns 0 if success, otherwise error code
   */
  static int hdlcdev_attach(struct net_device *dev, unsigned short encoding,
  			  unsigned short parity)
  {
  	struct slgt_info *info = dev_to_port(dev);
  	unsigned char  new_encoding;
  	unsigned short new_crctype;
  
  	/* return error if TTY interface open */
  	if (info->port.count)
  		return -EBUSY;
  
  	DBGINFO(("%s hdlcdev_attach\n", info->device_name));
  
  	switch (encoding)
  	{
  	case ENCODING_NRZ:        new_encoding = HDLC_ENCODING_NRZ; break;
  	case ENCODING_NRZI:       new_encoding = HDLC_ENCODING_NRZI_SPACE; break;
  	case ENCODING_FM_MARK:    new_encoding = HDLC_ENCODING_BIPHASE_MARK; break;
  	case ENCODING_FM_SPACE:   new_encoding = HDLC_ENCODING_BIPHASE_SPACE; break;
  	case ENCODING_MANCHESTER: new_encoding = HDLC_ENCODING_BIPHASE_LEVEL; break;
  	default: return -EINVAL;
  	}
  
  	switch (parity)
  	{
  	case PARITY_NONE:            new_crctype = HDLC_CRC_NONE; break;
  	case PARITY_CRC16_PR1_CCITT: new_crctype = HDLC_CRC_16_CCITT; break;
  	case PARITY_CRC32_PR1_CCITT: new_crctype = HDLC_CRC_32_CCITT; break;
  	default: return -EINVAL;
  	}
  
  	info->params.encoding = new_encoding;
  	info->params.crc_type = new_crctype;
  
  	/* if network interface up, reprogram hardware */
  	if (info->netcount)
  		program_hw(info);
  
  	return 0;
  }
  
  /**
   * called by generic HDLC layer to send frame
   *
   * skb  socket buffer containing HDLC frame
   * dev  pointer to network device structure
   */
  static netdev_tx_t hdlcdev_xmit(struct sk_buff *skb,
  				      struct net_device *dev)
  {
  	struct slgt_info *info = dev_to_port(dev);
  	unsigned long flags;
  
  	DBGINFO(("%s hdlc_xmit\n", dev->name));
  
  	if (!skb->len)
  		return NETDEV_TX_OK;
  
  	/* stop sending until this frame completes */
  	netif_stop_queue(dev);
  
  	/* update network statistics */
  	dev->stats.tx_packets++;
  	dev->stats.tx_bytes += skb->len;
  
  	/* save start time for transmit timeout detection */
  	netif_trans_update(dev);
  
  	spin_lock_irqsave(&info->lock, flags);
  	tx_load(info, skb->data, skb->len);
  	spin_unlock_irqrestore(&info->lock, flags);
  
  	/* done with socket buffer, so free it */
  	dev_kfree_skb(skb);
  
  	return NETDEV_TX_OK;
  }
  
  /**
   * called by network layer when interface enabled
   * claim resources and initialize hardware
   *
   * dev  pointer to network device structure
   *
   * returns 0 if success, otherwise error code
   */
  static int hdlcdev_open(struct net_device *dev)
  {
  	struct slgt_info *info = dev_to_port(dev);
  	int rc;
  	unsigned long flags;
  
  	if (!try_module_get(THIS_MODULE))
  		return -EBUSY;
  
  	DBGINFO(("%s hdlcdev_open\n", dev->name));
  
  	/* generic HDLC layer open processing */
  	rc = hdlc_open(dev);
  	if (rc)
  		return rc;
  
  	/* arbitrate between network and tty opens */
  	spin_lock_irqsave(&info->netlock, flags);
  	if (info->port.count != 0 || info->netcount != 0) {
  		DBGINFO(("%s hdlc_open busy\n", dev->name));
  		spin_unlock_irqrestore(&info->netlock, flags);
  		return -EBUSY;
  	}
  	info->netcount=1;
  	spin_unlock_irqrestore(&info->netlock, flags);
  
  	/* claim resources and init adapter */
  	if ((rc = startup(info)) != 0) {
  		spin_lock_irqsave(&info->netlock, flags);
  		info->netcount=0;
  		spin_unlock_irqrestore(&info->netlock, flags);
  		return rc;
  	}
  
  	/* assert RTS and DTR, apply hardware settings */
  	info->signals |= SerialSignal_RTS | SerialSignal_DTR;
  	program_hw(info);
  
  	/* enable network layer transmit */
  	netif_trans_update(dev);
  	netif_start_queue(dev);
  
  	/* inform generic HDLC layer of current DCD status */
  	spin_lock_irqsave(&info->lock, flags);
  	get_signals(info);
  	spin_unlock_irqrestore(&info->lock, flags);
  	if (info->signals & SerialSignal_DCD)
  		netif_carrier_on(dev);
  	else
  		netif_carrier_off(dev);
  	return 0;
  }
  
  /**
   * called by network layer when interface is disabled
   * shutdown hardware and release resources
   *
   * dev  pointer to network device structure
   *
   * returns 0 if success, otherwise error code
   */
  static int hdlcdev_close(struct net_device *dev)
  {
  	struct slgt_info *info = dev_to_port(dev);
  	unsigned long flags;
  
  	DBGINFO(("%s hdlcdev_close\n", dev->name));
  
  	netif_stop_queue(dev);
  
  	/* shutdown adapter and release resources */
  	shutdown(info);
  
  	hdlc_close(dev);
  
  	spin_lock_irqsave(&info->netlock, flags);
  	info->netcount=0;
  	spin_unlock_irqrestore(&info->netlock, flags);
  
  	module_put(THIS_MODULE);
  	return 0;
  }
  
  /**
   * called by network layer to process IOCTL call to network device
   *
   * dev  pointer to network device structure
   * ifr  pointer to network interface request structure
   * cmd  IOCTL command code
   *
   * returns 0 if success, otherwise error code
   */
  static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
  {
  	const size_t size = sizeof(sync_serial_settings);
  	sync_serial_settings new_line;
  	sync_serial_settings __user *line = ifr->ifr_settings.ifs_ifsu.sync;
  	struct slgt_info *info = dev_to_port(dev);
  	unsigned int flags;
  
  	DBGINFO(("%s hdlcdev_ioctl\n", dev->name));
  
  	/* return error if TTY interface open */
  	if (info->port.count)
  		return -EBUSY;
  
  	if (cmd != SIOCWANDEV)
  		return hdlc_ioctl(dev, ifr, cmd);
  
  	memset(&new_line, 0, sizeof(new_line));
  
  	switch(ifr->ifr_settings.type) {
  	case IF_GET_IFACE: /* return current sync_serial_settings */
  
  		ifr->ifr_settings.type = IF_IFACE_SYNC_SERIAL;
  		if (ifr->ifr_settings.size < size) {
  			ifr->ifr_settings.size = size; /* data size wanted */
  			return -ENOBUFS;
  		}
  
  		flags = info->params.flags & (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
  					      HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
  					      HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
  					      HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
  
  		switch (flags){
  		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN): new_line.clock_type = CLOCK_EXT; break;
  		case (HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_INT; break;
  		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_TXINT; break;
  		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN): new_line.clock_type = CLOCK_TXFROMRX; break;
  		default: new_line.clock_type = CLOCK_DEFAULT;
  		}
  
  		new_line.clock_rate = info->params.clock_speed;
  		new_line.loopback   = info->params.loopback ? 1:0;
  
  		if (copy_to_user(line, &new_line, size))
  			return -EFAULT;
  		return 0;
  
  	case IF_IFACE_SYNC_SERIAL: /* set sync_serial_settings */
  
  		if(!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		if (copy_from_user(&new_line, line, size))
  			return -EFAULT;
  
  		switch (new_line.clock_type)
  		{
  		case CLOCK_EXT:      flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN; break;
  		case CLOCK_TXFROMRX: flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN; break;
  		case CLOCK_INT:      flags = HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG;    break;
  		case CLOCK_TXINT:    flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG;    break;
  		case CLOCK_DEFAULT:  flags = info->params.flags &
  					     (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
  					      HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
  					      HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
  					      HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN); break;
  		default: return -EINVAL;
  		}
  
  		if (new_line.loopback != 0 && new_line.loopback != 1)
  			return -EINVAL;
  
  		info->params.flags &= ~(HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
  					HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
  					HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
  					HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
  		info->params.flags |= flags;
  
  		info->params.loopback = new_line.loopback;
  
  		if (flags & (HDLC_FLAG_RXC_BRG | HDLC_FLAG_TXC_BRG))
  			info->params.clock_speed = new_line.clock_rate;
  		else
  			info->params.clock_speed = 0;
  
  		/* if network interface up, reprogram hardware */
  		if (info->netcount)
  			program_hw(info);
  		return 0;
  
  	default:
  		return hdlc_ioctl(dev, ifr, cmd);
  	}
  }
  
  /**
   * called by network layer when transmit timeout is detected
   *
   * dev  pointer to network device structure
   */
  static void hdlcdev_tx_timeout(struct net_device *dev, unsigned int txqueue)
  {
  	struct slgt_info *info = dev_to_port(dev);
  	unsigned long flags;
  
  	DBGINFO(("%s hdlcdev_tx_timeout\n", dev->name));
  
  	dev->stats.tx_errors++;
  	dev->stats.tx_aborted_errors++;
  
  	spin_lock_irqsave(&info->lock,flags);
  	tx_stop(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	netif_wake_queue(dev);
  }
  
  /**
   * called by device driver when transmit completes
   * reenable network layer transmit if stopped
   *
   * info  pointer to device instance information
   */
  static void hdlcdev_tx_done(struct slgt_info *info)
  {
  	if (netif_queue_stopped(info->netdev))
  		netif_wake_queue(info->netdev);
  }
  
  /**
   * called by device driver when frame received
   * pass frame to network layer
   *
   * info  pointer to device instance information
   * buf   pointer to buffer contianing frame data
   * size  count of data bytes in buf
   */
  static void hdlcdev_rx(struct slgt_info *info, char *buf, int size)
  {
  	struct sk_buff *skb = dev_alloc_skb(size);
  	struct net_device *dev = info->netdev;
  
  	DBGINFO(("%s hdlcdev_rx\n", dev->name));
  
  	if (skb == NULL) {
  		DBGERR(("%s: can't alloc skb, drop packet\n", dev->name));
  		dev->stats.rx_dropped++;
  		return;
  	}
  
  	skb_put_data(skb, buf, size);
  
  	skb->protocol = hdlc_type_trans(skb, dev);
  
  	dev->stats.rx_packets++;
  	dev->stats.rx_bytes += size;
  
  	netif_rx(skb);
  }
  
  static const struct net_device_ops hdlcdev_ops = {
  	.ndo_open       = hdlcdev_open,
  	.ndo_stop       = hdlcdev_close,
  	.ndo_start_xmit = hdlc_start_xmit,
  	.ndo_do_ioctl   = hdlcdev_ioctl,
  	.ndo_tx_timeout = hdlcdev_tx_timeout,
  };
  
  /**
   * called by device driver when adding device instance
   * do generic HDLC initialization
   *
   * info  pointer to device instance information
   *
   * returns 0 if success, otherwise error code
   */
  static int hdlcdev_init(struct slgt_info *info)
  {
  	int rc;
  	struct net_device *dev;
  	hdlc_device *hdlc;
  
  	/* allocate and initialize network and HDLC layer objects */
  
  	dev = alloc_hdlcdev(info);
  	if (!dev) {
  		printk(KERN_ERR "%s hdlc device alloc failure\n", info->device_name);
  		return -ENOMEM;
  	}
  
  	/* for network layer reporting purposes only */
  	dev->mem_start = info->phys_reg_addr;
  	dev->mem_end   = info->phys_reg_addr + SLGT_REG_SIZE - 1;
  	dev->irq       = info->irq_level;
  
  	/* network layer callbacks and settings */
  	dev->netdev_ops	    = &hdlcdev_ops;
  	dev->watchdog_timeo = 10 * HZ;
  	dev->tx_queue_len   = 50;
  
  	/* generic HDLC layer callbacks and settings */
  	hdlc         = dev_to_hdlc(dev);
  	hdlc->attach = hdlcdev_attach;
  	hdlc->xmit   = hdlcdev_xmit;
  
  	/* register objects with HDLC layer */
  	rc = register_hdlc_device(dev);
  	if (rc) {
  		printk(KERN_WARNING "%s:unable to register hdlc device\n",__FILE__);
  		free_netdev(dev);
  		return rc;
  	}
  
  	info->netdev = dev;
  	return 0;
  }
  
  /**
   * called by device driver when removing device instance
   * do generic HDLC cleanup
   *
   * info  pointer to device instance information
   */
  static void hdlcdev_exit(struct slgt_info *info)
  {
  	unregister_hdlc_device(info->netdev);
  	free_netdev(info->netdev);
  	info->netdev = NULL;
  }
  
  #endif /* ifdef CONFIG_HDLC */
  
  /*
   * get async data from rx DMA buffers
   */
  static void rx_async(struct slgt_info *info)
  {
   	struct mgsl_icount *icount = &info->icount;
  	unsigned int start, end;
  	unsigned char *p;
  	unsigned char status;
  	struct slgt_desc *bufs = info->rbufs;
  	int i, count;
  	int chars = 0;
  	int stat;
  	unsigned char ch;
  
  	start = end = info->rbuf_current;
  
  	while(desc_complete(bufs[end])) {
  		count = desc_count(bufs[end]) - info->rbuf_index;
  		p     = bufs[end].buf + info->rbuf_index;
  
  		DBGISR(("%s rx_async count=%d\n", info->device_name, count));
  		DBGDATA(info, p, count, "rx");
  
  		for(i=0 ; i < count; i+=2, p+=2) {
  			ch = *p;
  			icount->rx++;
  
  			stat = 0;
  
  			status = *(p + 1) & (BIT1 + BIT0);
  			if (status) {
  				if (status & BIT1)
  					icount->parity++;
  				else if (status & BIT0)
  					icount->frame++;
  				/* discard char if tty control flags say so */
  				if (status & info->ignore_status_mask)
  					continue;
  				if (status & BIT1)
  					stat = TTY_PARITY;
  				else if (status & BIT0)
  					stat = TTY_FRAME;
  			}
  			tty_insert_flip_char(&info->port, ch, stat);
  			chars++;
  		}
  
  		if (i < count) {
  			/* receive buffer not completed */
  			info->rbuf_index += i;
  			mod_timer(&info->rx_timer, jiffies + 1);
  			break;
  		}
  
  		info->rbuf_index = 0;
  		free_rbufs(info, end, end);
  
  		if (++end == info->rbuf_count)
  			end = 0;
  
  		/* if entire list searched then no frame available */
  		if (end == start)
  			break;
  	}
  
  	if (chars)
  		tty_flip_buffer_push(&info->port);
  }
  
  /*
   * return next bottom half action to perform
   */
  static int bh_action(struct slgt_info *info)
  {
  	unsigned long flags;
  	int rc;
  
  	spin_lock_irqsave(&info->lock,flags);
  
  	if (info->pending_bh & BH_RECEIVE) {
  		info->pending_bh &= ~BH_RECEIVE;
  		rc = BH_RECEIVE;
  	} else if (info->pending_bh & BH_TRANSMIT) {
  		info->pending_bh &= ~BH_TRANSMIT;
  		rc = BH_TRANSMIT;
  	} else if (info->pending_bh & BH_STATUS) {
  		info->pending_bh &= ~BH_STATUS;
  		rc = BH_STATUS;
  	} else {
  		/* Mark BH routine as complete */
  		info->bh_running = false;
  		info->bh_requested = false;
  		rc = 0;
  	}
  
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	return rc;
  }
  
  /*
   * perform bottom half processing
   */
  static void bh_handler(struct work_struct *work)
  {
  	struct slgt_info *info = container_of(work, struct slgt_info, task);
  	int action;
  
  	info->bh_running = true;
  
  	while((action = bh_action(info))) {
  		switch (action) {
  		case BH_RECEIVE:
  			DBGBH(("%s bh receive\n", info->device_name));
  			switch(info->params.mode) {
  			case MGSL_MODE_ASYNC:
  				rx_async(info);
  				break;
  			case MGSL_MODE_HDLC:
  				while(rx_get_frame(info));
  				break;
  			case MGSL_MODE_RAW:
  			case MGSL_MODE_MONOSYNC:
  			case MGSL_MODE_BISYNC:
  			case MGSL_MODE_XSYNC:
  				while(rx_get_buf(info));
  				break;
  			}
  			/* restart receiver if rx DMA buffers exhausted */
  			if (info->rx_restart)
  				rx_start(info);
  			break;
  		case BH_TRANSMIT:
  			bh_transmit(info);
  			break;
  		case BH_STATUS:
  			DBGBH(("%s bh status\n", info->device_name));
  			info->ri_chkcount = 0;
  			info->dsr_chkcount = 0;
  			info->dcd_chkcount = 0;
  			info->cts_chkcount = 0;
  			break;
  		default:
  			DBGBH(("%s unknown action\n", info->device_name));
  			break;
  		}
  	}
  	DBGBH(("%s bh_handler exit\n", info->device_name));
  }
  
  static void bh_transmit(struct slgt_info *info)
  {
  	struct tty_struct *tty = info->port.tty;
  
  	DBGBH(("%s bh_transmit\n", info->device_name));
  	if (tty)
  		tty_wakeup(tty);
  }
  
  static void dsr_change(struct slgt_info *info, unsigned short status)
  {
  	if (status & BIT3) {
  		info->signals |= SerialSignal_DSR;
  		info->input_signal_events.dsr_up++;
  	} else {
  		info->signals &= ~SerialSignal_DSR;
  		info->input_signal_events.dsr_down++;
  	}
  	DBGISR(("dsr_change %s signals=%04X\n", info->device_name, info->signals));
  	if ((info->dsr_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
  		slgt_irq_off(info, IRQ_DSR);
  		return;
  	}
  	info->icount.dsr++;
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  	info->pending_bh |= BH_STATUS;
  }
  
  static void cts_change(struct slgt_info *info, unsigned short status)
  {
  	if (status & BIT2) {
  		info->signals |= SerialSignal_CTS;
  		info->input_signal_events.cts_up++;
  	} else {
  		info->signals &= ~SerialSignal_CTS;
  		info->input_signal_events.cts_down++;
  	}
  	DBGISR(("cts_change %s signals=%04X\n", info->device_name, info->signals));
  	if ((info->cts_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
  		slgt_irq_off(info, IRQ_CTS);
  		return;
  	}
  	info->icount.cts++;
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  	info->pending_bh |= BH_STATUS;
  
  	if (tty_port_cts_enabled(&info->port)) {
  		if (info->port.tty) {
  			if (info->port.tty->hw_stopped) {
  				if (info->signals & SerialSignal_CTS) {
  		 			info->port.tty->hw_stopped = 0;
  					info->pending_bh |= BH_TRANSMIT;
  					return;
  				}
  			} else {
  				if (!(info->signals & SerialSignal_CTS))
  		 			info->port.tty->hw_stopped = 1;
  			}
  		}
  	}
  }
  
  static void dcd_change(struct slgt_info *info, unsigned short status)
  {
  	if (status & BIT1) {
  		info->signals |= SerialSignal_DCD;
  		info->input_signal_events.dcd_up++;
  	} else {
  		info->signals &= ~SerialSignal_DCD;
  		info->input_signal_events.dcd_down++;
  	}
  	DBGISR(("dcd_change %s signals=%04X\n", info->device_name, info->signals));
  	if ((info->dcd_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
  		slgt_irq_off(info, IRQ_DCD);
  		return;
  	}
  	info->icount.dcd++;
  #if SYNCLINK_GENERIC_HDLC
  	if (info->netcount) {
  		if (info->signals & SerialSignal_DCD)
  			netif_carrier_on(info->netdev);
  		else
  			netif_carrier_off(info->netdev);
  	}
  #endif
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  	info->pending_bh |= BH_STATUS;
  
  	if (tty_port_check_carrier(&info->port)) {
  		if (info->signals & SerialSignal_DCD)
  			wake_up_interruptible(&info->port.open_wait);
  		else {
  			if (info->port.tty)
  				tty_hangup(info->port.tty);
  		}
  	}
  }
  
  static void ri_change(struct slgt_info *info, unsigned short status)
  {
  	if (status & BIT0) {
  		info->signals |= SerialSignal_RI;
  		info->input_signal_events.ri_up++;
  	} else {
  		info->signals &= ~SerialSignal_RI;
  		info->input_signal_events.ri_down++;
  	}
  	DBGISR(("ri_change %s signals=%04X\n", info->device_name, info->signals));
  	if ((info->ri_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
  		slgt_irq_off(info, IRQ_RI);
  		return;
  	}
  	info->icount.rng++;
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  	info->pending_bh |= BH_STATUS;
  }
  
  static void isr_rxdata(struct slgt_info *info)
  {
  	unsigned int count = info->rbuf_fill_count;
  	unsigned int i = info->rbuf_fill_index;
  	unsigned short reg;
  
  	while (rd_reg16(info, SSR) & IRQ_RXDATA) {
  		reg = rd_reg16(info, RDR);
  		DBGISR(("isr_rxdata %s RDR=%04X\n", info->device_name, reg));
  		if (desc_complete(info->rbufs[i])) {
  			/* all buffers full */
  			rx_stop(info);
  			info->rx_restart = true;
  			continue;
  		}
  		info->rbufs[i].buf[count++] = (unsigned char)reg;
  		/* async mode saves status byte to buffer for each data byte */
  		if (info->params.mode == MGSL_MODE_ASYNC)
  			info->rbufs[i].buf[count++] = (unsigned char)(reg >> 8);
  		if (count == info->rbuf_fill_level || (reg & BIT10)) {
  			/* buffer full or end of frame */
  			set_desc_count(info->rbufs[i], count);
  			set_desc_status(info->rbufs[i], BIT15 | (reg >> 8));
  			info->rbuf_fill_count = count = 0;
  			if (++i == info->rbuf_count)
  				i = 0;
  			info->pending_bh |= BH_RECEIVE;
  		}
  	}
  
  	info->rbuf_fill_index = i;
  	info->rbuf_fill_count = count;
  }
  
  static void isr_serial(struct slgt_info *info)
  {
  	unsigned short status = rd_reg16(info, SSR);
  
  	DBGISR(("%s isr_serial status=%04X\n", info->device_name, status));
  
  	wr_reg16(info, SSR, status); /* clear pending */
  
  	info->irq_occurred = true;
  
  	if (info->params.mode == MGSL_MODE_ASYNC) {
  		if (status & IRQ_TXIDLE) {
  			if (info->tx_active)
  				isr_txeom(info, status);
  		}
  		if (info->rx_pio && (status & IRQ_RXDATA))
  			isr_rxdata(info);
  		if ((status & IRQ_RXBREAK) && (status & RXBREAK)) {
  			info->icount.brk++;
  			/* process break detection if tty control allows */
  			if (info->port.tty) {
  				if (!(status & info->ignore_status_mask)) {
  					if (info->read_status_mask & MASK_BREAK) {
  						tty_insert_flip_char(&info->port, 0, TTY_BREAK);
  						if (info->port.flags & ASYNC_SAK)
  							do_SAK(info->port.tty);
  					}
  				}
  			}
  		}
  	} else {
  		if (status & (IRQ_TXIDLE + IRQ_TXUNDER))
  			isr_txeom(info, status);
  		if (info->rx_pio && (status & IRQ_RXDATA))
  			isr_rxdata(info);
  		if (status & IRQ_RXIDLE) {
  			if (status & RXIDLE)
  				info->icount.rxidle++;
  			else
  				info->icount.exithunt++;
  			wake_up_interruptible(&info->event_wait_q);
  		}
  
  		if (status & IRQ_RXOVER)
  			rx_start(info);
  	}
  
  	if (status & IRQ_DSR)
  		dsr_change(info, status);
  	if (status & IRQ_CTS)
  		cts_change(info, status);
  	if (status & IRQ_DCD)
  		dcd_change(info, status);
  	if (status & IRQ_RI)
  		ri_change(info, status);
  }
  
  static void isr_rdma(struct slgt_info *info)
  {
  	unsigned int status = rd_reg32(info, RDCSR);
  
  	DBGISR(("%s isr_rdma status=%08x\n", info->device_name, status));
  
  	/* RDCSR (rx DMA control/status)
  	 *
  	 * 31..07  reserved
  	 * 06      save status byte to DMA buffer
  	 * 05      error
  	 * 04      eol (end of list)
  	 * 03      eob (end of buffer)
  	 * 02      IRQ enable
  	 * 01      reset
  	 * 00      enable
  	 */
  	wr_reg32(info, RDCSR, status);	/* clear pending */
  
  	if (status & (BIT5 + BIT4)) {
  		DBGISR(("%s isr_rdma rx_restart=1\n", info->device_name));
  		info->rx_restart = true;
  	}
  	info->pending_bh |= BH_RECEIVE;
  }
  
  static void isr_tdma(struct slgt_info *info)
  {
  	unsigned int status = rd_reg32(info, TDCSR);
  
  	DBGISR(("%s isr_tdma status=%08x\n", info->device_name, status));
  
  	/* TDCSR (tx DMA control/status)
  	 *
  	 * 31..06  reserved
  	 * 05      error
  	 * 04      eol (end of list)
  	 * 03      eob (end of buffer)
  	 * 02      IRQ enable
  	 * 01      reset
  	 * 00      enable
  	 */
  	wr_reg32(info, TDCSR, status);	/* clear pending */
  
  	if (status & (BIT5 + BIT4 + BIT3)) {
  		// another transmit buffer has completed
  		// run bottom half to get more send data from user
  		info->pending_bh |= BH_TRANSMIT;
  	}
  }
  
  /*
   * return true if there are unsent tx DMA buffers, otherwise false
   *
   * if there are unsent buffers then info->tbuf_start
   * is set to index of first unsent buffer
   */
  static bool unsent_tbufs(struct slgt_info *info)
  {
  	unsigned int i = info->tbuf_current;
  	bool rc = false;
  
  	/*
  	 * search backwards from last loaded buffer (precedes tbuf_current)
  	 * for first unsent buffer (desc_count > 0)
  	 */
  
  	do {
  		if (i)
  			i--;
  		else
  			i = info->tbuf_count - 1;
  		if (!desc_count(info->tbufs[i]))
  			break;
  		info->tbuf_start = i;
  		rc = true;
  	} while (i != info->tbuf_current);
  
  	return rc;
  }
  
  static void isr_txeom(struct slgt_info *info, unsigned short status)
  {
  	DBGISR(("%s txeom status=%04x\n", info->device_name, status));
  
  	slgt_irq_off(info, IRQ_TXDATA + IRQ_TXIDLE + IRQ_TXUNDER);
  	tdma_reset(info);
  	if (status & IRQ_TXUNDER) {
  		unsigned short val = rd_reg16(info, TCR);
  		wr_reg16(info, TCR, (unsigned short)(val | BIT2)); /* set reset bit */
  		wr_reg16(info, TCR, val); /* clear reset bit */
  	}
  
  	if (info->tx_active) {
  		if (info->params.mode != MGSL_MODE_ASYNC) {
  			if (status & IRQ_TXUNDER)
  				info->icount.txunder++;
  			else if (status & IRQ_TXIDLE)
  				info->icount.txok++;
  		}
  
  		if (unsent_tbufs(info)) {
  			tx_start(info);
  			update_tx_timer(info);
  			return;
  		}
  		info->tx_active = false;
  
  		del_timer(&info->tx_timer);
  
  		if (info->params.mode != MGSL_MODE_ASYNC && info->drop_rts_on_tx_done) {
  			info->signals &= ~SerialSignal_RTS;
  			info->drop_rts_on_tx_done = false;
  			set_signals(info);
  		}
  
  #if SYNCLINK_GENERIC_HDLC
  		if (info->netcount)
  			hdlcdev_tx_done(info);
  		else
  #endif
  		{
  			if (info->port.tty && (info->port.tty->stopped || info->port.tty->hw_stopped)) {
  				tx_stop(info);
  				return;
  			}
  			info->pending_bh |= BH_TRANSMIT;
  		}
  	}
  }
  
  static void isr_gpio(struct slgt_info *info, unsigned int changed, unsigned int state)
  {
  	struct cond_wait *w, *prev;
  
  	/* wake processes waiting for specific transitions */
  	for (w = info->gpio_wait_q, prev = NULL ; w != NULL ; w = w->next) {
  		if (w->data & changed) {
  			w->data = state;
  			wake_up_interruptible(&w->q);
  			if (prev != NULL)
  				prev->next = w->next;
  			else
  				info->gpio_wait_q = w->next;
  		} else
  			prev = w;
  	}
  }
  
  /* interrupt service routine
   *
   * 	irq	interrupt number
   * 	dev_id	device ID supplied during interrupt registration
   */
  static irqreturn_t slgt_interrupt(int dummy, void *dev_id)
  {
  	struct slgt_info *info = dev_id;
  	unsigned int gsr;
  	unsigned int i;
  
  	DBGISR(("slgt_interrupt irq=%d entry\n", info->irq_level));
  
  	while((gsr = rd_reg32(info, GSR) & 0xffffff00)) {
  		DBGISR(("%s gsr=%08x\n", info->device_name, gsr));
  		info->irq_occurred = true;
  		for(i=0; i < info->port_count ; i++) {
  			if (info->port_array[i] == NULL)
  				continue;
  			spin_lock(&info->port_array[i]->lock);
  			if (gsr & (BIT8 << i))
  				isr_serial(info->port_array[i]);
  			if (gsr & (BIT16 << (i*2)))
  				isr_rdma(info->port_array[i]);
  			if (gsr & (BIT17 << (i*2)))
  				isr_tdma(info->port_array[i]);
  			spin_unlock(&info->port_array[i]->lock);
  		}
  	}
  
  	if (info->gpio_present) {
  		unsigned int state;
  		unsigned int changed;
  		spin_lock(&info->lock);
  		while ((changed = rd_reg32(info, IOSR)) != 0) {
  			DBGISR(("%s iosr=%08x\n", info->device_name, changed));
  			/* read latched state of GPIO signals */
  			state = rd_reg32(info, IOVR);
  			/* clear pending GPIO interrupt bits */
  			wr_reg32(info, IOSR, changed);
  			for (i=0 ; i < info->port_count ; i++) {
  				if (info->port_array[i] != NULL)
  					isr_gpio(info->port_array[i], changed, state);
  			}
  		}
  		spin_unlock(&info->lock);
  	}
  
  	for(i=0; i < info->port_count ; i++) {
  		struct slgt_info *port = info->port_array[i];
  		if (port == NULL)
  			continue;
  		spin_lock(&port->lock);
  		if ((port->port.count || port->netcount) &&
  		    port->pending_bh && !port->bh_running &&
  		    !port->bh_requested) {
  			DBGISR(("%s bh queued\n", port->device_name));
  			schedule_work(&port->task);
  			port->bh_requested = true;
  		}
  		spin_unlock(&port->lock);
  	}
  
  	DBGISR(("slgt_interrupt irq=%d exit\n", info->irq_level));
  	return IRQ_HANDLED;
  }
  
  static int startup(struct slgt_info *info)
  {
  	DBGINFO(("%s startup\n", info->device_name));
  
  	if (tty_port_initialized(&info->port))
  		return 0;
  
  	if (!info->tx_buf) {
  		info->tx_buf = kmalloc(info->max_frame_size, GFP_KERNEL);
  		if (!info->tx_buf) {
  			DBGERR(("%s can't allocate tx buffer\n", info->device_name));
  			return -ENOMEM;
  		}
  	}
  
  	info->pending_bh = 0;
  
  	memset(&info->icount, 0, sizeof(info->icount));
  
  	/* program hardware for current parameters */
  	change_params(info);
  
  	if (info->port.tty)
  		clear_bit(TTY_IO_ERROR, &info->port.tty->flags);
  
  	tty_port_set_initialized(&info->port, 1);
  
  	return 0;
  }
  
  /*
   *  called by close() and hangup() to shutdown hardware
   */
  static void shutdown(struct slgt_info *info)
  {
  	unsigned long flags;
  
  	if (!tty_port_initialized(&info->port))
  		return;
  
  	DBGINFO(("%s shutdown\n", info->device_name));
  
  	/* clear status wait queue because status changes */
  	/* can't happen after shutting down the hardware */
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  
  	del_timer_sync(&info->tx_timer);
  	del_timer_sync(&info->rx_timer);
  
  	kfree(info->tx_buf);
  	info->tx_buf = NULL;
  
  	spin_lock_irqsave(&info->lock,flags);
  
  	tx_stop(info);
  	rx_stop(info);
  
  	slgt_irq_off(info, IRQ_ALL | IRQ_MASTER);
  
   	if (!info->port.tty || info->port.tty->termios.c_cflag & HUPCL) {
  		info->signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
  		set_signals(info);
  	}
  
  	flush_cond_wait(&info->gpio_wait_q);
  
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	if (info->port.tty)
  		set_bit(TTY_IO_ERROR, &info->port.tty->flags);
  
  	tty_port_set_initialized(&info->port, 0);
  }
  
  static void program_hw(struct slgt_info *info)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&info->lock,flags);
  
  	rx_stop(info);
  	tx_stop(info);
  
  	if (info->params.mode != MGSL_MODE_ASYNC ||
  	    info->netcount)
  		sync_mode(info);
  	else
  		async_mode(info);
  
  	set_signals(info);
  
  	info->dcd_chkcount = 0;
  	info->cts_chkcount = 0;
  	info->ri_chkcount = 0;
  	info->dsr_chkcount = 0;
  
  	slgt_irq_on(info, IRQ_DCD | IRQ_CTS | IRQ_DSR | IRQ_RI);
  	get_signals(info);
  
  	if (info->netcount ||
  	    (info->port.tty && info->port.tty->termios.c_cflag & CREAD))
  		rx_start(info);
  
  	spin_unlock_irqrestore(&info->lock,flags);
  }
  
  /*
   * reconfigure adapter based on new parameters
   */
  static void change_params(struct slgt_info *info)
  {
  	unsigned cflag;
  	int bits_per_char;
  
  	if (!info->port.tty)
  		return;
  	DBGINFO(("%s change_params\n", info->device_name));
  
  	cflag = info->port.tty->termios.c_cflag;
  
  	/* if B0 rate (hangup) specified then negate RTS and DTR */
  	/* otherwise assert RTS and DTR */
   	if (cflag & CBAUD)
  		info->signals |= SerialSignal_RTS | SerialSignal_DTR;
  	else
  		info->signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
  
  	/* byte size and parity */
  
  	switch (cflag & CSIZE) {
  	case CS5: info->params.data_bits = 5; break;
  	case CS6: info->params.data_bits = 6; break;
  	case CS7: info->params.data_bits = 7; break;
  	case CS8: info->params.data_bits = 8; break;
  	default:  info->params.data_bits = 7; break;
  	}
  
  	info->params.stop_bits = (cflag & CSTOPB) ? 2 : 1;
  
  	if (cflag & PARENB)
  		info->params.parity = (cflag & PARODD) ? ASYNC_PARITY_ODD : ASYNC_PARITY_EVEN;
  	else
  		info->params.parity = ASYNC_PARITY_NONE;
  
  	/* calculate number of jiffies to transmit a full
  	 * FIFO (32 bytes) at specified data rate
  	 */
  	bits_per_char = info->params.data_bits +
  			info->params.stop_bits + 1;
  
  	info->params.data_rate = tty_get_baud_rate(info->port.tty);
  
  	if (info->params.data_rate) {
  		info->timeout = (32*HZ*bits_per_char) /
  				info->params.data_rate;
  	}
  	info->timeout += HZ/50;		/* Add .02 seconds of slop */
  
  	tty_port_set_cts_flow(&info->port, cflag & CRTSCTS);
  	tty_port_set_check_carrier(&info->port, ~cflag & CLOCAL);
  
  	/* process tty input control flags */
  
  	info->read_status_mask = IRQ_RXOVER;
  	if (I_INPCK(info->port.tty))
  		info->read_status_mask |= MASK_PARITY | MASK_FRAMING;
  	if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
  		info->read_status_mask |= MASK_BREAK;
  	if (I_IGNPAR(info->port.tty))
  		info->ignore_status_mask |= MASK_PARITY | MASK_FRAMING;
  	if (I_IGNBRK(info->port.tty)) {
  		info->ignore_status_mask |= MASK_BREAK;
  		/* If ignoring parity and break indicators, ignore
  		 * overruns too.  (For real raw support).
  		 */
  		if (I_IGNPAR(info->port.tty))
  			info->ignore_status_mask |= MASK_OVERRUN;
  	}
  
  	program_hw(info);
  }
  
  static int get_stats(struct slgt_info *info, struct mgsl_icount __user *user_icount)
  {
  	DBGINFO(("%s get_stats\n",  info->device_name));
  	if (!user_icount) {
  		memset(&info->icount, 0, sizeof(info->icount));
  	} else {
  		if (copy_to_user(user_icount, &info->icount, sizeof(struct mgsl_icount)))
  			return -EFAULT;
  	}
  	return 0;
  }
  
  static int get_params(struct slgt_info *info, MGSL_PARAMS __user *user_params)
  {
  	DBGINFO(("%s get_params\n", info->device_name));
  	if (copy_to_user(user_params, &info->params, sizeof(MGSL_PARAMS)))
  		return -EFAULT;
  	return 0;
  }
  
  static int set_params(struct slgt_info *info, MGSL_PARAMS __user *new_params)
  {
   	unsigned long flags;
  	MGSL_PARAMS tmp_params;
  
  	DBGINFO(("%s set_params\n", info->device_name));
  	if (copy_from_user(&tmp_params, new_params, sizeof(MGSL_PARAMS)))
  		return -EFAULT;
  
  	spin_lock_irqsave(&info->lock, flags);
  	if (tmp_params.mode == MGSL_MODE_BASE_CLOCK)
  		info->base_clock = tmp_params.clock_speed;
  	else
  		memcpy(&info->params, &tmp_params, sizeof(MGSL_PARAMS));
  	spin_unlock_irqrestore(&info->lock, flags);
  
  	program_hw(info);
  
  	return 0;
  }
  
  static int get_txidle(struct slgt_info *info, int __user *idle_mode)
  {
  	DBGINFO(("%s get_txidle=%d\n", info->device_name, info->idle_mode));
  	if (put_user(info->idle_mode, idle_mode))
  		return -EFAULT;
  	return 0;
  }
  
  static int set_txidle(struct slgt_info *info, int idle_mode)
  {
   	unsigned long flags;
  	DBGINFO(("%s set_txidle(%d)\n", info->device_name, idle_mode));
  	spin_lock_irqsave(&info->lock,flags);
  	info->idle_mode = idle_mode;
  	if (info->params.mode != MGSL_MODE_ASYNC)
  		tx_set_idle(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  static int tx_enable(struct slgt_info *info, int enable)
  {
   	unsigned long flags;
  	DBGINFO(("%s tx_enable(%d)\n", info->device_name, enable));
  	spin_lock_irqsave(&info->lock,flags);
  	if (enable) {
  		if (!info->tx_enabled)
  			tx_start(info);
  	} else {
  		if (info->tx_enabled)
  			tx_stop(info);
  	}
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  /*
   * abort transmit HDLC frame
   */
  static int tx_abort(struct slgt_info *info)
  {
   	unsigned long flags;
  	DBGINFO(("%s tx_abort\n", info->device_name));
  	spin_lock_irqsave(&info->lock,flags);
  	tdma_reset(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  static int rx_enable(struct slgt_info *info, int enable)
  {
   	unsigned long flags;
  	unsigned int rbuf_fill_level;
  	DBGINFO(("%s rx_enable(%08x)\n", info->device_name, enable));
  	spin_lock_irqsave(&info->lock,flags);
  	/*
  	 * enable[31..16] = receive DMA buffer fill level
  	 * 0 = noop (leave fill level unchanged)
  	 * fill level must be multiple of 4 and <= buffer size
  	 */
  	rbuf_fill_level = ((unsigned int)enable) >> 16;
  	if (rbuf_fill_level) {
  		if ((rbuf_fill_level > DMABUFSIZE) || (rbuf_fill_level % 4)) {
  			spin_unlock_irqrestore(&info->lock, flags);
  			return -EINVAL;
  		}
  		info->rbuf_fill_level = rbuf_fill_level;
  		if (rbuf_fill_level < 128)
  			info->rx_pio = 1; /* PIO mode */
  		else
  			info->rx_pio = 0; /* DMA mode */
  		rx_stop(info); /* restart receiver to use new fill level */
  	}
  
  	/*
  	 * enable[1..0] = receiver enable command
  	 * 0 = disable
  	 * 1 = enable
  	 * 2 = enable or force hunt mode if already enabled
  	 */
  	enable &= 3;
  	if (enable) {
  		if (!info->rx_enabled)
  			rx_start(info);
  		else if (enable == 2) {
  			/* force hunt mode (write 1 to RCR[3]) */
  			wr_reg16(info, RCR, rd_reg16(info, RCR) | BIT3);
  		}
  	} else {
  		if (info->rx_enabled)
  			rx_stop(info);
  	}
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  /*
   *  wait for specified event to occur
   */
  static int wait_mgsl_event(struct slgt_info *info, int __user *mask_ptr)
  {
   	unsigned long flags;
  	int s;
  	int rc=0;
  	struct mgsl_icount cprev, cnow;
  	int events;
  	int mask;
  	struct	_input_signal_events oldsigs, newsigs;
  	DECLARE_WAITQUEUE(wait, current);
  
  	if (get_user(mask, mask_ptr))
  		return -EFAULT;
  
  	DBGINFO(("%s wait_mgsl_event(%d)\n", info->device_name, mask));
  
  	spin_lock_irqsave(&info->lock,flags);
  
  	/* return immediately if state matches requested events */
  	get_signals(info);
  	s = info->signals;
  
  	events = mask &
  		( ((s & SerialSignal_DSR) ? MgslEvent_DsrActive:MgslEvent_DsrInactive) +
   		  ((s & SerialSignal_DCD) ? MgslEvent_DcdActive:MgslEvent_DcdInactive) +
  		  ((s & SerialSignal_CTS) ? MgslEvent_CtsActive:MgslEvent_CtsInactive) +
  		  ((s & SerialSignal_RI)  ? MgslEvent_RiActive :MgslEvent_RiInactive) );
  	if (events) {
  		spin_unlock_irqrestore(&info->lock,flags);
  		goto exit;
  	}
  
  	/* save current irq counts */
  	cprev = info->icount;
  	oldsigs = info->input_signal_events;
  
  	/* enable hunt and idle irqs if needed */
  	if (mask & (MgslEvent_ExitHuntMode+MgslEvent_IdleReceived)) {
  		unsigned short val = rd_reg16(info, SCR);
  		if (!(val & IRQ_RXIDLE))
  			wr_reg16(info, SCR, (unsigned short)(val | IRQ_RXIDLE));
  	}
  
  	set_current_state(TASK_INTERRUPTIBLE);
  	add_wait_queue(&info->event_wait_q, &wait);
  
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	for(;;) {
  		schedule();
  		if (signal_pending(current)) {
  			rc = -ERESTARTSYS;
  			break;
  		}
  
  		/* get current irq counts */
  		spin_lock_irqsave(&info->lock,flags);
  		cnow = info->icount;
  		newsigs = info->input_signal_events;
  		set_current_state(TASK_INTERRUPTIBLE);
  		spin_unlock_irqrestore(&info->lock,flags);
  
  		/* if no change, wait aborted for some reason */
  		if (newsigs.dsr_up   == oldsigs.dsr_up   &&
  		    newsigs.dsr_down == oldsigs.dsr_down &&
  		    newsigs.dcd_up   == oldsigs.dcd_up   &&
  		    newsigs.dcd_down == oldsigs.dcd_down &&
  		    newsigs.cts_up   == oldsigs.cts_up   &&
  		    newsigs.cts_down == oldsigs.cts_down &&
  		    newsigs.ri_up    == oldsigs.ri_up    &&
  		    newsigs.ri_down  == oldsigs.ri_down  &&
  		    cnow.exithunt    == cprev.exithunt   &&
  		    cnow.rxidle      == cprev.rxidle) {
  			rc = -EIO;
  			break;
  		}
  
  		events = mask &
  			( (newsigs.dsr_up   != oldsigs.dsr_up   ? MgslEvent_DsrActive:0)   +
  			  (newsigs.dsr_down != oldsigs.dsr_down ? MgslEvent_DsrInactive:0) +
  			  (newsigs.dcd_up   != oldsigs.dcd_up   ? MgslEvent_DcdActive:0)   +
  			  (newsigs.dcd_down != oldsigs.dcd_down ? MgslEvent_DcdInactive:0) +
  			  (newsigs.cts_up   != oldsigs.cts_up   ? MgslEvent_CtsActive:0)   +
  			  (newsigs.cts_down != oldsigs.cts_down ? MgslEvent_CtsInactive:0) +
  			  (newsigs.ri_up    != oldsigs.ri_up    ? MgslEvent_RiActive:0)    +
  			  (newsigs.ri_down  != oldsigs.ri_down  ? MgslEvent_RiInactive:0)  +
  			  (cnow.exithunt    != cprev.exithunt   ? MgslEvent_ExitHuntMode:0) +
  			  (cnow.rxidle      != cprev.rxidle     ? MgslEvent_IdleReceived:0) );
  		if (events)
  			break;
  
  		cprev = cnow;
  		oldsigs = newsigs;
  	}
  
  	remove_wait_queue(&info->event_wait_q, &wait);
  	set_current_state(TASK_RUNNING);
  
  
  	if (mask & (MgslEvent_ExitHuntMode + MgslEvent_IdleReceived)) {
  		spin_lock_irqsave(&info->lock,flags);
  		if (!waitqueue_active(&info->event_wait_q)) {
  			/* disable enable exit hunt mode/idle rcvd IRQs */
  			wr_reg16(info, SCR,
  				(unsigned short)(rd_reg16(info, SCR) & ~IRQ_RXIDLE));
  		}
  		spin_unlock_irqrestore(&info->lock,flags);
  	}
  exit:
  	if (rc == 0)
  		rc = put_user(events, mask_ptr);
  	return rc;
  }
  
  static int get_interface(struct slgt_info *info, int __user *if_mode)
  {
  	DBGINFO(("%s get_interface=%x\n", info->device_name, info->if_mode));
  	if (put_user(info->if_mode, if_mode))
  		return -EFAULT;
  	return 0;
  }
  
  static int set_interface(struct slgt_info *info, int if_mode)
  {
   	unsigned long flags;
  	unsigned short val;
  
  	DBGINFO(("%s set_interface=%x)\n", info->device_name, if_mode));
  	spin_lock_irqsave(&info->lock,flags);
  	info->if_mode = if_mode;
  
  	msc_set_vcr(info);
  
  	/* TCR (tx control) 07  1=RTS driver control */
  	val = rd_reg16(info, TCR);
  	if (info->if_mode & MGSL_INTERFACE_RTS_EN)
  		val |= BIT7;
  	else
  		val &= ~BIT7;
  	wr_reg16(info, TCR, val);
  
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  static int get_xsync(struct slgt_info *info, int __user *xsync)
  {
  	DBGINFO(("%s get_xsync=%x\n", info->device_name, info->xsync));
  	if (put_user(info->xsync, xsync))
  		return -EFAULT;
  	return 0;
  }
  
  /*
   * set extended sync pattern (1 to 4 bytes) for extended sync mode
   *
   * sync pattern is contained in least significant bytes of value
   * most significant byte of sync pattern is oldest (1st sent/detected)
   */
  static int set_xsync(struct slgt_info *info, int xsync)
  {
  	unsigned long flags;
  
  	DBGINFO(("%s set_xsync=%x)\n", info->device_name, xsync));
  	spin_lock_irqsave(&info->lock, flags);
  	info->xsync = xsync;
  	wr_reg32(info, XSR, xsync);
  	spin_unlock_irqrestore(&info->lock, flags);
  	return 0;
  }
  
  static int get_xctrl(struct slgt_info *info, int __user *xctrl)
  {
  	DBGINFO(("%s get_xctrl=%x\n", info->device_name, info->xctrl));
  	if (put_user(info->xctrl, xctrl))
  		return -EFAULT;
  	return 0;
  }
  
  /*
   * set extended control options
   *
   * xctrl[31:19] reserved, must be zero
   * xctrl[18:17] extended sync pattern length in bytes
   *              00 = 1 byte  in xsr[7:0]
   *              01 = 2 bytes in xsr[15:0]
   *              10 = 3 bytes in xsr[23:0]
   *              11 = 4 bytes in xsr[31:0]
   * xctrl[16]    1 = enable terminal count, 0=disabled
   * xctrl[15:0]  receive terminal count for fixed length packets
   *              value is count minus one (0 = 1 byte packet)
   *              when terminal count is reached, receiver
   *              automatically returns to hunt mode and receive
   *              FIFO contents are flushed to DMA buffers with
   *              end of frame (EOF) status
   */
  static int set_xctrl(struct slgt_info *info, int xctrl)
  {
  	unsigned long flags;
  
  	DBGINFO(("%s set_xctrl=%x)\n", info->device_name, xctrl));
  	spin_lock_irqsave(&info->lock, flags);
  	info->xctrl = xctrl;
  	wr_reg32(info, XCR, xctrl);
  	spin_unlock_irqrestore(&info->lock, flags);
  	return 0;
  }
  
  /*
   * set general purpose IO pin state and direction
   *
   * user_gpio fields:
   * state   each bit indicates a pin state
   * smask   set bit indicates pin state to set
   * dir     each bit indicates a pin direction (0=input, 1=output)
   * dmask   set bit indicates pin direction to set
   */
  static int set_gpio(struct slgt_info *info, struct gpio_desc __user *user_gpio)
  {
   	unsigned long flags;
  	struct gpio_desc gpio;
  	__u32 data;
  
  	if (!info->gpio_present)
  		return -EINVAL;
  	if (copy_from_user(&gpio, user_gpio, sizeof(gpio)))
  		return -EFAULT;
  	DBGINFO(("%s set_gpio state=%08x smask=%08x dir=%08x dmask=%08x\n",
  		 info->device_name, gpio.state, gpio.smask,
  		 gpio.dir, gpio.dmask));
  
  	spin_lock_irqsave(&info->port_array[0]->lock, flags);
  	if (gpio.dmask) {
  		data = rd_reg32(info, IODR);
  		data |= gpio.dmask & gpio.dir;
  		data &= ~(gpio.dmask & ~gpio.dir);
  		wr_reg32(info, IODR, data);
  	}
  	if (gpio.smask) {
  		data = rd_reg32(info, IOVR);
  		data |= gpio.smask & gpio.state;
  		data &= ~(gpio.smask & ~gpio.state);
  		wr_reg32(info, IOVR, data);
  	}
  	spin_unlock_irqrestore(&info->port_array[0]->lock, flags);
  
  	return 0;
  }
  
  /*
   * get general purpose IO pin state and direction
   */
  static int get_gpio(struct slgt_info *info, struct gpio_desc __user *user_gpio)
  {
  	struct gpio_desc gpio;
  	if (!info->gpio_present)
  		return -EINVAL;
  	gpio.state = rd_reg32(info, IOVR);
  	gpio.smask = 0xffffffff;
  	gpio.dir   = rd_reg32(info, IODR);
  	gpio.dmask = 0xffffffff;
  	if (copy_to_user(user_gpio, &gpio, sizeof(gpio)))
  		return -EFAULT;
  	DBGINFO(("%s get_gpio state=%08x dir=%08x\n",
  		 info->device_name, gpio.state, gpio.dir));
  	return 0;
  }
  
  /*
   * conditional wait facility
   */
  static void init_cond_wait(struct cond_wait *w, unsigned int data)
  {
  	init_waitqueue_head(&w->q);
  	init_waitqueue_entry(&w->wait, current);
  	w->data = data;
  }
  
  static void add_cond_wait(struct cond_wait **head, struct cond_wait *w)
  {
  	set_current_state(TASK_INTERRUPTIBLE);
  	add_wait_queue(&w->q, &w->wait);
  	w->next = *head;
  	*head = w;
  }
  
  static void remove_cond_wait(struct cond_wait **head, struct cond_wait *cw)
  {
  	struct cond_wait *w, *prev;
  	remove_wait_queue(&cw->q, &cw->wait);
  	set_current_state(TASK_RUNNING);
  	for (w = *head, prev = NULL ; w != NULL ; prev = w, w = w->next) {
  		if (w == cw) {
  			if (prev != NULL)
  				prev->next = w->next;
  			else
  				*head = w->next;
  			break;
  		}
  	}
  }
  
  static void flush_cond_wait(struct cond_wait **head)
  {
  	while (*head != NULL) {
  		wake_up_interruptible(&(*head)->q);
  		*head = (*head)->next;
  	}
  }
  
  /*
   * wait for general purpose I/O pin(s) to enter specified state
   *
   * user_gpio fields:
   * state - bit indicates target pin state
   * smask - set bit indicates watched pin
   *
   * The wait ends when at least one watched pin enters the specified
   * state. When 0 (no error) is returned, user_gpio->state is set to the
   * state of all GPIO pins when the wait ends.
   *
   * Note: Each pin may be a dedicated input, dedicated output, or
   * configurable input/output. The number and configuration of pins
   * varies with the specific adapter model. Only input pins (dedicated
   * or configured) can be monitored with this function.
   */
  static int wait_gpio(struct slgt_info *info, struct gpio_desc __user *user_gpio)
  {
   	unsigned long flags;
  	int rc = 0;
  	struct gpio_desc gpio;
  	struct cond_wait wait;
  	u32 state;
  
  	if (!info->gpio_present)
  		return -EINVAL;
  	if (copy_from_user(&gpio, user_gpio, sizeof(gpio)))
  		return -EFAULT;
  	DBGINFO(("%s wait_gpio() state=%08x smask=%08x\n",
  		 info->device_name, gpio.state, gpio.smask));
  	/* ignore output pins identified by set IODR bit */
  	if ((gpio.smask &= ~rd_reg32(info, IODR)) == 0)
  		return -EINVAL;
  	init_cond_wait(&wait, gpio.smask);
  
  	spin_lock_irqsave(&info->port_array[0]->lock, flags);
  	/* enable interrupts for watched pins */
  	wr_reg32(info, IOER, rd_reg32(info, IOER) | gpio.smask);
  	/* get current pin states */
  	state = rd_reg32(info, IOVR);
  
  	if (gpio.smask & ~(state ^ gpio.state)) {
  		/* already in target state */
  		gpio.state = state;
  	} else {
  		/* wait for target state */
  		add_cond_wait(&info->gpio_wait_q, &wait);
  		spin_unlock_irqrestore(&info->port_array[0]->lock, flags);
  		schedule();
  		if (signal_pending(current))
  			rc = -ERESTARTSYS;
  		else
  			gpio.state = wait.data;
  		spin_lock_irqsave(&info->port_array[0]->lock, flags);
  		remove_cond_wait(&info->gpio_wait_q, &wait);
  	}
  
  	/* disable all GPIO interrupts if no waiting processes */
  	if (info->gpio_wait_q == NULL)
  		wr_reg32(info, IOER, 0);
  	spin_unlock_irqrestore(&info->port_array[0]->lock, flags);
  
  	if ((rc == 0) && copy_to_user(user_gpio, &gpio, sizeof(gpio)))
  		rc = -EFAULT;
  	return rc;
  }
  
  static int modem_input_wait(struct slgt_info *info,int arg)
  {
   	unsigned long flags;
  	int rc;
  	struct mgsl_icount cprev, cnow;
  	DECLARE_WAITQUEUE(wait, current);
  
  	/* save current irq counts */
  	spin_lock_irqsave(&info->lock,flags);
  	cprev = info->icount;
  	add_wait_queue(&info->status_event_wait_q, &wait);
  	set_current_state(TASK_INTERRUPTIBLE);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	for(;;) {
  		schedule();
  		if (signal_pending(current)) {
  			rc = -ERESTARTSYS;
  			break;
  		}
  
  		/* get new irq counts */
  		spin_lock_irqsave(&info->lock,flags);
  		cnow = info->icount;
  		set_current_state(TASK_INTERRUPTIBLE);
  		spin_unlock_irqrestore(&info->lock,flags);
  
  		/* if no change, wait aborted for some reason */
  		if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
  		    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
  			rc = -EIO;
  			break;
  		}
  
  		/* check for change in caller specified modem input */
  		if ((arg & TIOCM_RNG && cnow.rng != cprev.rng) ||
  		    (arg & TIOCM_DSR && cnow.dsr != cprev.dsr) ||
  		    (arg & TIOCM_CD  && cnow.dcd != cprev.dcd) ||
  		    (arg & TIOCM_CTS && cnow.cts != cprev.cts)) {
  			rc = 0;
  			break;
  		}
  
  		cprev = cnow;
  	}
  	remove_wait_queue(&info->status_event_wait_q, &wait);
  	set_current_state(TASK_RUNNING);
  	return rc;
  }
  
  /*
   *  return state of serial control and status signals
   */
  static int tiocmget(struct tty_struct *tty)
  {
  	struct slgt_info *info = tty->driver_data;
  	unsigned int result;
   	unsigned long flags;
  
  	spin_lock_irqsave(&info->lock,flags);
   	get_signals(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	result = ((info->signals & SerialSignal_RTS) ? TIOCM_RTS:0) +
  		((info->signals & SerialSignal_DTR) ? TIOCM_DTR:0) +
  		((info->signals & SerialSignal_DCD) ? TIOCM_CAR:0) +
  		((info->signals & SerialSignal_RI)  ? TIOCM_RNG:0) +
  		((info->signals & SerialSignal_DSR) ? TIOCM_DSR:0) +
  		((info->signals & SerialSignal_CTS) ? TIOCM_CTS:0);
  
  	DBGINFO(("%s tiocmget value=%08X\n", info->device_name, result));
  	return result;
  }
  
  /*
   * set modem control signals (DTR/RTS)
   *
   * 	cmd	signal command: TIOCMBIS = set bit TIOCMBIC = clear bit
   *		TIOCMSET = set/clear signal values
   * 	value	bit mask for command
   */
  static int tiocmset(struct tty_struct *tty,
  		    unsigned int set, unsigned int clear)
  {
  	struct slgt_info *info = tty->driver_data;
   	unsigned long flags;
  
  	DBGINFO(("%s tiocmset(%x,%x)\n", info->device_name, set, clear));
  
  	if (set & TIOCM_RTS)
  		info->signals |= SerialSignal_RTS;
  	if (set & TIOCM_DTR)
  		info->signals |= SerialSignal_DTR;
  	if (clear & TIOCM_RTS)
  		info->signals &= ~SerialSignal_RTS;
  	if (clear & TIOCM_DTR)
  		info->signals &= ~SerialSignal_DTR;
  
  	spin_lock_irqsave(&info->lock,flags);
  	set_signals(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  	return 0;
  }
  
  static int carrier_raised(struct tty_port *port)
  {
  	unsigned long flags;
  	struct slgt_info *info = container_of(port, struct slgt_info, port);
  
  	spin_lock_irqsave(&info->lock,flags);
  	get_signals(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  	return (info->signals & SerialSignal_DCD) ? 1 : 0;
  }
  
  static void dtr_rts(struct tty_port *port, int on)
  {
  	unsigned long flags;
  	struct slgt_info *info = container_of(port, struct slgt_info, port);
  
  	spin_lock_irqsave(&info->lock,flags);
  	if (on)
  		info->signals |= SerialSignal_RTS | SerialSignal_DTR;
  	else
  		info->signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
  	set_signals(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  }
  
  
  /*
   *  block current process until the device is ready to open
   */
  static int block_til_ready(struct tty_struct *tty, struct file *filp,
  			   struct slgt_info *info)
  {
  	DECLARE_WAITQUEUE(wait, current);
  	int		retval;
  	bool		do_clocal = false;
  	unsigned long	flags;
  	int		cd;
  	struct tty_port *port = &info->port;
  
  	DBGINFO(("%s block_til_ready\n", tty->driver->name));
  
  	if (filp->f_flags & O_NONBLOCK || tty_io_error(tty)) {
  		/* nonblock mode is set or port is not enabled */
  		tty_port_set_active(port, 1);
  		return 0;
  	}
  
  	if (C_CLOCAL(tty))
  		do_clocal = true;
  
  	/* Wait for carrier detect and the line to become
  	 * free (i.e., not in use by the callout).  While we are in
  	 * this loop, port->count is dropped by one, so that
  	 * close() knows when to free things.  We restore it upon
  	 * exit, either normal or abnormal.
  	 */
  
  	retval = 0;
  	add_wait_queue(&port->open_wait, &wait);
  
  	spin_lock_irqsave(&info->lock, flags);
  	port->count--;
  	spin_unlock_irqrestore(&info->lock, flags);
  	port->blocked_open++;
  
  	while (1) {
  		if (C_BAUD(tty) && tty_port_initialized(port))
  			tty_port_raise_dtr_rts(port);
  
  		set_current_state(TASK_INTERRUPTIBLE);
  
  		if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
  			retval = (port->flags & ASYNC_HUP_NOTIFY) ?
  					-EAGAIN : -ERESTARTSYS;
  			break;
  		}
  
  		cd = tty_port_carrier_raised(port);
  		if (do_clocal || cd)
  			break;
  
  		if (signal_pending(current)) {
  			retval = -ERESTARTSYS;
  			break;
  		}
  
  		DBGINFO(("%s block_til_ready wait\n", tty->driver->name));
  		tty_unlock(tty);
  		schedule();
  		tty_lock(tty);
  	}
  
  	set_current_state(TASK_RUNNING);
  	remove_wait_queue(&port->open_wait, &wait);
  
  	if (!tty_hung_up_p(filp))
  		port->count++;
  	port->blocked_open--;
  
  	if (!retval)
  		tty_port_set_active(port, 1);
  
  	DBGINFO(("%s block_til_ready ready, rc=%d\n", tty->driver->name, retval));
  	return retval;
  }
  
  /*
   * allocate buffers used for calling line discipline receive_buf
   * directly in synchronous mode
   * note: add 5 bytes to max frame size to allow appending
   * 32-bit CRC and status byte when configured to do so
   */
  static int alloc_tmp_rbuf(struct slgt_info *info)
  {
  	info->tmp_rbuf = kmalloc(info->max_frame_size + 5, GFP_KERNEL);
  	if (info->tmp_rbuf == NULL)
  		return -ENOMEM;
  	/* unused flag buffer to satisfy receive_buf calling interface */
  	info->flag_buf = kzalloc(info->max_frame_size + 5, GFP_KERNEL);
  	if (!info->flag_buf) {
  		kfree(info->tmp_rbuf);
  		info->tmp_rbuf = NULL;
  		return -ENOMEM;
  	}
  	return 0;
  }
  
  static void free_tmp_rbuf(struct slgt_info *info)
  {
  	kfree(info->tmp_rbuf);
  	info->tmp_rbuf = NULL;
  	kfree(info->flag_buf);
  	info->flag_buf = NULL;
  }
  
  /*
   * allocate DMA descriptor lists.
   */
  static int alloc_desc(struct slgt_info *info)
  {
  	unsigned int i;
  	unsigned int pbufs;
  
  	/* allocate memory to hold descriptor lists */
  	info->bufs = pci_zalloc_consistent(info->pdev, DESC_LIST_SIZE,
  					   &info->bufs_dma_addr);
  	if (info->bufs == NULL)
  		return -ENOMEM;
  
  	info->rbufs = (struct slgt_desc*)info->bufs;
  	info->tbufs = ((struct slgt_desc*)info->bufs) + info->rbuf_count;
  
  	pbufs = (unsigned int)info->bufs_dma_addr;
  
  	/*
  	 * Build circular lists of descriptors
  	 */
  
  	for (i=0; i < info->rbuf_count; i++) {
  		/* physical address of this descriptor */
  		info->rbufs[i].pdesc = pbufs + (i * sizeof(struct slgt_desc));
  
  		/* physical address of next descriptor */
  		if (i == info->rbuf_count - 1)
  			info->rbufs[i].next = cpu_to_le32(pbufs);
  		else
  			info->rbufs[i].next = cpu_to_le32(pbufs + ((i+1) * sizeof(struct slgt_desc)));
  		set_desc_count(info->rbufs[i], DMABUFSIZE);
  	}
  
  	for (i=0; i < info->tbuf_count; i++) {
  		/* physical address of this descriptor */
  		info->tbufs[i].pdesc = pbufs + ((info->rbuf_count + i) * sizeof(struct slgt_desc));
  
  		/* physical address of next descriptor */
  		if (i == info->tbuf_count - 1)
  			info->tbufs[i].next = cpu_to_le32(pbufs + info->rbuf_count * sizeof(struct slgt_desc));
  		else
  			info->tbufs[i].next = cpu_to_le32(pbufs + ((info->rbuf_count + i + 1) * sizeof(struct slgt_desc)));
  	}
  
  	return 0;
  }
  
  static void free_desc(struct slgt_info *info)
  {
  	if (info->bufs != NULL) {
  		pci_free_consistent(info->pdev, DESC_LIST_SIZE, info->bufs, info->bufs_dma_addr);
  		info->bufs  = NULL;
  		info->rbufs = NULL;
  		info->tbufs = NULL;
  	}
  }
  
  static int alloc_bufs(struct slgt_info *info, struct slgt_desc *bufs, int count)
  {
  	int i;
  	for (i=0; i < count; i++) {
  		if ((bufs[i].buf = pci_alloc_consistent(info->pdev, DMABUFSIZE, &bufs[i].buf_dma_addr)) == NULL)
  			return -ENOMEM;
  		bufs[i].pbuf  = cpu_to_le32((unsigned int)bufs[i].buf_dma_addr);
  	}
  	return 0;
  }
  
  static void free_bufs(struct slgt_info *info, struct slgt_desc *bufs, int count)
  {
  	int i;
  	for (i=0; i < count; i++) {
  		if (bufs[i].buf == NULL)
  			continue;
  		pci_free_consistent(info->pdev, DMABUFSIZE, bufs[i].buf, bufs[i].buf_dma_addr);
  		bufs[i].buf = NULL;
  	}
  }
  
  static int alloc_dma_bufs(struct slgt_info *info)
  {
  	info->rbuf_count = 32;
  	info->tbuf_count = 32;
  
  	if (alloc_desc(info) < 0 ||
  	    alloc_bufs(info, info->rbufs, info->rbuf_count) < 0 ||
  	    alloc_bufs(info, info->tbufs, info->tbuf_count) < 0 ||
  	    alloc_tmp_rbuf(info) < 0) {
  		DBGERR(("%s DMA buffer alloc fail\n", info->device_name));
  		return -ENOMEM;
  	}
  	reset_rbufs(info);
  	return 0;
  }
  
  static void free_dma_bufs(struct slgt_info *info)
  {
  	if (info->bufs) {
  		free_bufs(info, info->rbufs, info->rbuf_count);
  		free_bufs(info, info->tbufs, info->tbuf_count);
  		free_desc(info);
  	}
  	free_tmp_rbuf(info);
  }
  
  static int claim_resources(struct slgt_info *info)
  {
  	if (request_mem_region(info->phys_reg_addr, SLGT_REG_SIZE, "synclink_gt") == NULL) {
  		DBGERR(("%s reg addr conflict, addr=%08X\n",
  			info->device_name, info->phys_reg_addr));
  		info->init_error = DiagStatus_AddressConflict;
  		goto errout;
  	}
  	else
  		info->reg_addr_requested = true;
  
  	info->reg_addr = ioremap(info->phys_reg_addr, SLGT_REG_SIZE);
  	if (!info->reg_addr) {
  		DBGERR(("%s can't map device registers, addr=%08X\n",
  			info->device_name, info->phys_reg_addr));
  		info->init_error = DiagStatus_CantAssignPciResources;
  		goto errout;
  	}
  	return 0;
  
  errout:
  	release_resources(info);
  	return -ENODEV;
  }
  
  static void release_resources(struct slgt_info *info)
  {
  	if (info->irq_requested) {
  		free_irq(info->irq_level, info);
  		info->irq_requested = false;
  	}
  
  	if (info->reg_addr_requested) {
  		release_mem_region(info->phys_reg_addr, SLGT_REG_SIZE);
  		info->reg_addr_requested = false;
  	}
  
  	if (info->reg_addr) {
  		iounmap(info->reg_addr);
  		info->reg_addr = NULL;
  	}
  }
  
  /* Add the specified device instance data structure to the
   * global linked list of devices and increment the device count.
   */
  static void add_device(struct slgt_info *info)
  {
  	char *devstr;
  
  	info->next_device = NULL;
  	info->line = slgt_device_count;
  	sprintf(info->device_name, "%s%d", tty_dev_prefix, info->line);
  
  	if (info->line < MAX_DEVICES) {
  		if (maxframe[info->line])
  			info->max_frame_size = maxframe[info->line];
  	}
  
  	slgt_device_count++;
  
  	if (!slgt_device_list)
  		slgt_device_list = info;
  	else {
  		struct slgt_info *current_dev = slgt_device_list;
  		while(current_dev->next_device)
  			current_dev = current_dev->next_device;
  		current_dev->next_device = info;
  	}
  
  	if (info->max_frame_size < 4096)
  		info->max_frame_size = 4096;
  	else if (info->max_frame_size > 65535)
  		info->max_frame_size = 65535;
  
  	switch(info->pdev->device) {
  	case SYNCLINK_GT_DEVICE_ID:
  		devstr = "GT";
  		break;
  	case SYNCLINK_GT2_DEVICE_ID:
  		devstr = "GT2";
  		break;
  	case SYNCLINK_GT4_DEVICE_ID:
  		devstr = "GT4";
  		break;
  	case SYNCLINK_AC_DEVICE_ID:
  		devstr = "AC";
  		info->params.mode = MGSL_MODE_ASYNC;
  		break;
  	default:
  		devstr = "(unknown model)";
  	}
  	printk("SyncLink %s %s IO=%08x IRQ=%d MaxFrameSize=%u\n",
  		devstr, info->device_name, info->phys_reg_addr,
  		info->irq_level, info->max_frame_size);
  
  #if SYNCLINK_GENERIC_HDLC
  	hdlcdev_init(info);
  #endif
  }
  
  static const struct tty_port_operations slgt_port_ops = {
  	.carrier_raised = carrier_raised,
  	.dtr_rts = dtr_rts,
  };
  
  /*
   *  allocate device instance structure, return NULL on failure
   */
  static struct slgt_info *alloc_dev(int adapter_num, int port_num, struct pci_dev *pdev)
  {
  	struct slgt_info *info;
  
  	info = kzalloc(sizeof(struct slgt_info), GFP_KERNEL);
  
  	if (!info) {
  		DBGERR(("%s device alloc failed adapter=%d port=%d\n",
  			driver_name, adapter_num, port_num));
  	} else {
  		tty_port_init(&info->port);
  		info->port.ops = &slgt_port_ops;
  		info->magic = MGSL_MAGIC;
  		INIT_WORK(&info->task, bh_handler);
  		info->max_frame_size = 4096;
  		info->base_clock = 14745600;
  		info->rbuf_fill_level = DMABUFSIZE;
  		info->port.close_delay = 5*HZ/10;
  		info->port.closing_wait = 30*HZ;
  		init_waitqueue_head(&info->status_event_wait_q);
  		init_waitqueue_head(&info->event_wait_q);
  		spin_lock_init(&info->netlock);
  		memcpy(&info->params,&default_params,sizeof(MGSL_PARAMS));
  		info->idle_mode = HDLC_TXIDLE_FLAGS;
  		info->adapter_num = adapter_num;
  		info->port_num = port_num;
  
  		timer_setup(&info->tx_timer, tx_timeout, 0);
  		timer_setup(&info->rx_timer, rx_timeout, 0);
  
  		/* Copy configuration info to device instance data */
  		info->pdev = pdev;
  		info->irq_level = pdev->irq;
  		info->phys_reg_addr = pci_resource_start(pdev,0);
  
  		info->bus_type = MGSL_BUS_TYPE_PCI;
  		info->irq_flags = IRQF_SHARED;
  
  		info->init_error = -1; /* assume error, set to 0 on successful init */
  	}
  
  	return info;
  }
  
  static void device_init(int adapter_num, struct pci_dev *pdev)
  {
  	struct slgt_info *port_array[SLGT_MAX_PORTS];
  	int i;
  	int port_count = 1;
  
  	if (pdev->device == SYNCLINK_GT2_DEVICE_ID)
  		port_count = 2;
  	else if (pdev->device == SYNCLINK_GT4_DEVICE_ID)
  		port_count = 4;
  
  	/* allocate device instances for all ports */
  	for (i=0; i < port_count; ++i) {
  		port_array[i] = alloc_dev(adapter_num, i, pdev);
  		if (port_array[i] == NULL) {
  			for (--i; i >= 0; --i) {
  				tty_port_destroy(&port_array[i]->port);
  				kfree(port_array[i]);
  			}
  			return;
  		}
  	}
  
  	/* give copy of port_array to all ports and add to device list  */
  	for (i=0; i < port_count; ++i) {
  		memcpy(port_array[i]->port_array, port_array, sizeof(port_array));
  		add_device(port_array[i]);
  		port_array[i]->port_count = port_count;
  		spin_lock_init(&port_array[i]->lock);
  	}
  
  	/* Allocate and claim adapter resources */
  	if (!claim_resources(port_array[0])) {
  
  		alloc_dma_bufs(port_array[0]);
  
  		/* copy resource information from first port to others */
  		for (i = 1; i < port_count; ++i) {
  			port_array[i]->irq_level = port_array[0]->irq_level;
  			port_array[i]->reg_addr  = port_array[0]->reg_addr;
  			alloc_dma_bufs(port_array[i]);
  		}
  
  		if (request_irq(port_array[0]->irq_level,
  					slgt_interrupt,
  					port_array[0]->irq_flags,
  					port_array[0]->device_name,
  					port_array[0]) < 0) {
  			DBGERR(("%s request_irq failed IRQ=%d\n",
  				port_array[0]->device_name,
  				port_array[0]->irq_level));
  		} else {
  			port_array[0]->irq_requested = true;
  			adapter_test(port_array[0]);
  			for (i=1 ; i < port_count ; i++) {
  				port_array[i]->init_error = port_array[0]->init_error;
  				port_array[i]->gpio_present = port_array[0]->gpio_present;
  			}
  		}
  	}
  
  	for (i = 0; i < port_count; ++i) {
  		struct slgt_info *info = port_array[i];
  		tty_port_register_device(&info->port, serial_driver, info->line,
  				&info->pdev->dev);
  	}
  }
  
  static int init_one(struct pci_dev *dev,
  			      const struct pci_device_id *ent)
  {
  	if (pci_enable_device(dev)) {
  		printk("error enabling pci device %p\n", dev);
  		return -EIO;
  	}
  	pci_set_master(dev);
  	device_init(slgt_device_count, dev);
  	return 0;
  }
  
  static void remove_one(struct pci_dev *dev)
  {
  }
  
  static const struct tty_operations ops = {
  	.open = open,
  	.close = close,
  	.write = write,
  	.put_char = put_char,
  	.flush_chars = flush_chars,
  	.write_room = write_room,
  	.chars_in_buffer = chars_in_buffer,
  	.flush_buffer = flush_buffer,
  	.ioctl = ioctl,
  	.compat_ioctl = slgt_compat_ioctl,
  	.throttle = throttle,
  	.unthrottle = unthrottle,
  	.send_xchar = send_xchar,
  	.break_ctl = set_break,
  	.wait_until_sent = wait_until_sent,
  	.set_termios = set_termios,
  	.stop = tx_hold,
  	.start = tx_release,
  	.hangup = hangup,
  	.tiocmget = tiocmget,
  	.tiocmset = tiocmset,
  	.get_icount = get_icount,
  	.proc_show = synclink_gt_proc_show,
  };
  
  static void slgt_cleanup(void)
  {
  	int rc;
  	struct slgt_info *info;
  	struct slgt_info *tmp;
  
  	printk(KERN_INFO "unload %s\n", driver_name);
  
  	if (serial_driver) {
  		for (info=slgt_device_list ; info != NULL ; info=info->next_device)
  			tty_unregister_device(serial_driver, info->line);
  		rc = tty_unregister_driver(serial_driver);
  		if (rc)
  			DBGERR(("tty_unregister_driver error=%d\n", rc));
  		put_tty_driver(serial_driver);
  	}
  
  	/* reset devices */
  	info = slgt_device_list;
  	while(info) {
  		reset_port(info);
  		info = info->next_device;
  	}
  
  	/* release devices */
  	info = slgt_device_list;
  	while(info) {
  #if SYNCLINK_GENERIC_HDLC
  		hdlcdev_exit(info);
  #endif
  		free_dma_bufs(info);
  		free_tmp_rbuf(info);
  		if (info->port_num == 0)
  			release_resources(info);
  		tmp = info;
  		info = info->next_device;
  		tty_port_destroy(&tmp->port);
  		kfree(tmp);
  	}
  
  	if (pci_registered)
  		pci_unregister_driver(&pci_driver);
  }
  
  /*
   *  Driver initialization entry point.
   */
  static int __init slgt_init(void)
  {
  	int rc;
  
  	printk(KERN_INFO "%s\n", driver_name);
  
  	serial_driver = alloc_tty_driver(MAX_DEVICES);
  	if (!serial_driver) {
  		printk("%s can't allocate tty driver\n", driver_name);
  		return -ENOMEM;
  	}
  
  	/* Initialize the tty_driver structure */
  
  	serial_driver->driver_name = slgt_driver_name;
  	serial_driver->name = tty_dev_prefix;
  	serial_driver->major = ttymajor;
  	serial_driver->minor_start = 64;
  	serial_driver->type = TTY_DRIVER_TYPE_SERIAL;
  	serial_driver->subtype = SERIAL_TYPE_NORMAL;
  	serial_driver->init_termios = tty_std_termios;
  	serial_driver->init_termios.c_cflag =
  		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
  	serial_driver->init_termios.c_ispeed = 9600;
  	serial_driver->init_termios.c_ospeed = 9600;
  	serial_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
  	tty_set_operations(serial_driver, &ops);
  	if ((rc = tty_register_driver(serial_driver)) < 0) {
  		DBGERR(("%s can't register serial driver\n", driver_name));
  		put_tty_driver(serial_driver);
  		serial_driver = NULL;
  		goto error;
  	}
  
  	printk(KERN_INFO "%s, tty major#%d\n",
  	       driver_name, serial_driver->major);
  
  	slgt_device_count = 0;
  	if ((rc = pci_register_driver(&pci_driver)) < 0) {
  		printk("%s pci_register_driver error=%d\n", driver_name, rc);
  		goto error;
  	}
  	pci_registered = true;
  
  	if (!slgt_device_list)
  		printk("%s no devices found\n",driver_name);
  
  	return 0;
  
  error:
  	slgt_cleanup();
  	return rc;
  }
  
  static void __exit slgt_exit(void)
  {
  	slgt_cleanup();
  }
  
  module_init(slgt_init);
  module_exit(slgt_exit);
  
  /*
   * register access routines
   */
  
  #define CALC_REGADDR() \
  	unsigned long reg_addr = ((unsigned long)info->reg_addr) + addr; \
  	if (addr >= 0x80) \
  		reg_addr += (info->port_num) * 32; \
  	else if (addr >= 0x40)	\
  		reg_addr += (info->port_num) * 16;
  
  static __u8 rd_reg8(struct slgt_info *info, unsigned int addr)
  {
  	CALC_REGADDR();
  	return readb((void __iomem *)reg_addr);
  }
  
  static void wr_reg8(struct slgt_info *info, unsigned int addr, __u8 value)
  {
  	CALC_REGADDR();
  	writeb(value, (void __iomem *)reg_addr);
  }
  
  static __u16 rd_reg16(struct slgt_info *info, unsigned int addr)
  {
  	CALC_REGADDR();
  	return readw((void __iomem *)reg_addr);
  }
  
  static void wr_reg16(struct slgt_info *info, unsigned int addr, __u16 value)
  {
  	CALC_REGADDR();
  	writew(value, (void __iomem *)reg_addr);
  }
  
  static __u32 rd_reg32(struct slgt_info *info, unsigned int addr)
  {
  	CALC_REGADDR();
  	return readl((void __iomem *)reg_addr);
  }
  
  static void wr_reg32(struct slgt_info *info, unsigned int addr, __u32 value)
  {
  	CALC_REGADDR();
  	writel(value, (void __iomem *)reg_addr);
  }
  
  static void rdma_reset(struct slgt_info *info)
  {
  	unsigned int i;
  
  	/* set reset bit */
  	wr_reg32(info, RDCSR, BIT1);
  
  	/* wait for enable bit cleared */
  	for(i=0 ; i < 1000 ; i++)
  		if (!(rd_reg32(info, RDCSR) & BIT0))
  			break;
  }
  
  static void tdma_reset(struct slgt_info *info)
  {
  	unsigned int i;
  
  	/* set reset bit */
  	wr_reg32(info, TDCSR, BIT1);
  
  	/* wait for enable bit cleared */
  	for(i=0 ; i < 1000 ; i++)
  		if (!(rd_reg32(info, TDCSR) & BIT0))
  			break;
  }
  
  /*
   * enable internal loopback
   * TxCLK and RxCLK are generated from BRG
   * and TxD is looped back to RxD internally.
   */
  static void enable_loopback(struct slgt_info *info)
  {
  	/* SCR (serial control) BIT2=loopback enable */
  	wr_reg16(info, SCR, (unsigned short)(rd_reg16(info, SCR) | BIT2));
  
  	if (info->params.mode != MGSL_MODE_ASYNC) {
  		/* CCR (clock control)
  		 * 07..05  tx clock source (010 = BRG)
  		 * 04..02  rx clock source (010 = BRG)
  		 * 01      auxclk enable   (0 = disable)
  		 * 00      BRG enable      (1 = enable)
  		 *
  		 * 0100 1001
  		 */
  		wr_reg8(info, CCR, 0x49);
  
  		/* set speed if available, otherwise use default */
  		if (info->params.clock_speed)
  			set_rate(info, info->params.clock_speed);
  		else
  			set_rate(info, 3686400);
  	}
  }
  
  /*
   *  set baud rate generator to specified rate
   */
  static void set_rate(struct slgt_info *info, u32 rate)
  {
  	unsigned int div;
  	unsigned int osc = info->base_clock;
  
  	/* div = osc/rate - 1
  	 *
  	 * Round div up if osc/rate is not integer to
  	 * force to next slowest rate.
  	 */
  
  	if (rate) {
  		div = osc/rate;
  		if (!(osc % rate) && div)
  			div--;
  		wr_reg16(info, BDR, (unsigned short)div);
  	}
  }
  
  static void rx_stop(struct slgt_info *info)
  {
  	unsigned short val;
  
  	/* disable and reset receiver */
  	val = rd_reg16(info, RCR) & ~BIT1;          /* clear enable bit */
  	wr_reg16(info, RCR, (unsigned short)(val | BIT2)); /* set reset bit */
  	wr_reg16(info, RCR, val);                  /* clear reset bit */
  
  	slgt_irq_off(info, IRQ_RXOVER + IRQ_RXDATA + IRQ_RXIDLE);
  
  	/* clear pending rx interrupts */
  	wr_reg16(info, SSR, IRQ_RXIDLE + IRQ_RXOVER);
  
  	rdma_reset(info);
  
  	info->rx_enabled = false;
  	info->rx_restart = false;
  }
  
  static void rx_start(struct slgt_info *info)
  {
  	unsigned short val;
  
  	slgt_irq_off(info, IRQ_RXOVER + IRQ_RXDATA);
  
  	/* clear pending rx overrun IRQ */
  	wr_reg16(info, SSR, IRQ_RXOVER);
  
  	/* reset and disable receiver */
  	val = rd_reg16(info, RCR) & ~BIT1; /* clear enable bit */
  	wr_reg16(info, RCR, (unsigned short)(val | BIT2)); /* set reset bit */
  	wr_reg16(info, RCR, val);                  /* clear reset bit */
  
  	rdma_reset(info);
  	reset_rbufs(info);
  
  	if (info->rx_pio) {
  		/* rx request when rx FIFO not empty */
  		wr_reg16(info, SCR, (unsigned short)(rd_reg16(info, SCR) & ~BIT14));
  		slgt_irq_on(info, IRQ_RXDATA);
  		if (info->params.mode == MGSL_MODE_ASYNC) {
  			/* enable saving of rx status */
  			wr_reg32(info, RDCSR, BIT6);
  		}
  	} else {
  		/* rx request when rx FIFO half full */
  		wr_reg16(info, SCR, (unsigned short)(rd_reg16(info, SCR) | BIT14));
  		/* set 1st descriptor address */
  		wr_reg32(info, RDDAR, info->rbufs[0].pdesc);
  
  		if (info->params.mode != MGSL_MODE_ASYNC) {
  			/* enable rx DMA and DMA interrupt */
  			wr_reg32(info, RDCSR, (BIT2 + BIT0));
  		} else {
  			/* enable saving of rx status, rx DMA and DMA interrupt */
  			wr_reg32(info, RDCSR, (BIT6 + BIT2 + BIT0));
  		}
  	}
  
  	slgt_irq_on(info, IRQ_RXOVER);
  
  	/* enable receiver */
  	wr_reg16(info, RCR, (unsigned short)(rd_reg16(info, RCR) | BIT1));
  
  	info->rx_restart = false;
  	info->rx_enabled = true;
  }
  
  static void tx_start(struct slgt_info *info)
  {
  	if (!info->tx_enabled) {
  		wr_reg16(info, TCR,
  			 (unsigned short)((rd_reg16(info, TCR) | BIT1) & ~BIT2));
  		info->tx_enabled = true;
  	}
  
  	if (desc_count(info->tbufs[info->tbuf_start])) {
  		info->drop_rts_on_tx_done = false;
  
  		if (info->params.mode != MGSL_MODE_ASYNC) {
  			if (info->params.flags & HDLC_FLAG_AUTO_RTS) {
  				get_signals(info);
  				if (!(info->signals & SerialSignal_RTS)) {
  					info->signals |= SerialSignal_RTS;
  					set_signals(info);
  					info->drop_rts_on_tx_done = true;
  				}
  			}
  
  			slgt_irq_off(info, IRQ_TXDATA);
  			slgt_irq_on(info, IRQ_TXUNDER + IRQ_TXIDLE);
  			/* clear tx idle and underrun status bits */
  			wr_reg16(info, SSR, (unsigned short)(IRQ_TXIDLE + IRQ_TXUNDER));
  		} else {
  			slgt_irq_off(info, IRQ_TXDATA);
  			slgt_irq_on(info, IRQ_TXIDLE);
  			/* clear tx idle status bit */
  			wr_reg16(info, SSR, IRQ_TXIDLE);
  		}
  		/* set 1st descriptor address and start DMA */
  		wr_reg32(info, TDDAR, info->tbufs[info->tbuf_start].pdesc);
  		wr_reg32(info, TDCSR, BIT2 + BIT0);
  		info->tx_active = true;
  	}
  }
  
  static void tx_stop(struct slgt_info *info)
  {
  	unsigned short val;
  
  	del_timer(&info->tx_timer);
  
  	tdma_reset(info);
  
  	/* reset and disable transmitter */
  	val = rd_reg16(info, TCR) & ~BIT1;          /* clear enable bit */
  	wr_reg16(info, TCR, (unsigned short)(val | BIT2)); /* set reset bit */
  
  	slgt_irq_off(info, IRQ_TXDATA + IRQ_TXIDLE + IRQ_TXUNDER);
  
  	/* clear tx idle and underrun status bit */
  	wr_reg16(info, SSR, (unsigned short)(IRQ_TXIDLE + IRQ_TXUNDER));
  
  	reset_tbufs(info);
  
  	info->tx_enabled = false;
  	info->tx_active = false;
  }
  
  static void reset_port(struct slgt_info *info)
  {
  	if (!info->reg_addr)
  		return;
  
  	tx_stop(info);
  	rx_stop(info);
  
  	info->signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
  	set_signals(info);
  
  	slgt_irq_off(info, IRQ_ALL | IRQ_MASTER);
  }
  
  static void reset_adapter(struct slgt_info *info)
  {
  	int i;
  	for (i=0; i < info->port_count; ++i) {
  		if (info->port_array[i])
  			reset_port(info->port_array[i]);
  	}
  }
  
  static void async_mode(struct slgt_info *info)
  {
    	unsigned short val;
  
  	slgt_irq_off(info, IRQ_ALL | IRQ_MASTER);
  	tx_stop(info);
  	rx_stop(info);
  
  	/* TCR (tx control)
  	 *
  	 * 15..13  mode, 010=async
  	 * 12..10  encoding, 000=NRZ
  	 * 09      parity enable
  	 * 08      1=odd parity, 0=even parity
  	 * 07      1=RTS driver control
  	 * 06      1=break enable
  	 * 05..04  character length
  	 *         00=5 bits
  	 *         01=6 bits
  	 *         10=7 bits
  	 *         11=8 bits
  	 * 03      0=1 stop bit, 1=2 stop bits
  	 * 02      reset
  	 * 01      enable
  	 * 00      auto-CTS enable
  	 */
  	val = 0x4000;
  
  	if (info->if_mode & MGSL_INTERFACE_RTS_EN)
  		val |= BIT7;
  
  	if (info->params.parity != ASYNC_PARITY_NONE) {
  		val |= BIT9;
  		if (info->params.parity == ASYNC_PARITY_ODD)
  			val |= BIT8;
  	}
  
  	switch (info->params.data_bits)
  	{
  	case 6: val |= BIT4; break;
  	case 7: val |= BIT5; break;
  	case 8: val |= BIT5 + BIT4; break;
  	}
  
  	if (info->params.stop_bits != 1)
  		val |= BIT3;
  
  	if (info->params.flags & HDLC_FLAG_AUTO_CTS)
  		val |= BIT0;
  
  	wr_reg16(info, TCR, val);
  
  	/* RCR (rx control)
  	 *
  	 * 15..13  mode, 010=async
  	 * 12..10  encoding, 000=NRZ
  	 * 09      parity enable
  	 * 08      1=odd parity, 0=even parity
  	 * 07..06  reserved, must be 0
  	 * 05..04  character length
  	 *         00=5 bits
  	 *         01=6 bits
  	 *         10=7 bits
  	 *         11=8 bits
  	 * 03      reserved, must be zero
  	 * 02      reset
  	 * 01      enable
  	 * 00      auto-DCD enable
  	 */
  	val = 0x4000;
  
  	if (info->params.parity != ASYNC_PARITY_NONE) {
  		val |= BIT9;
  		if (info->params.parity == ASYNC_PARITY_ODD)
  			val |= BIT8;
  	}
  
  	switch (info->params.data_bits)
  	{
  	case 6: val |= BIT4; break;
  	case 7: val |= BIT5; break;
  	case 8: val |= BIT5 + BIT4; break;
  	}
  
  	if (info->params.flags & HDLC_FLAG_AUTO_DCD)
  		val |= BIT0;
  
  	wr_reg16(info, RCR, val);
  
  	/* CCR (clock control)
  	 *
  	 * 07..05  011 = tx clock source is BRG/16
  	 * 04..02  010 = rx clock source is BRG
  	 * 01      0 = auxclk disabled
  	 * 00      1 = BRG enabled
  	 *
  	 * 0110 1001
  	 */
  	wr_reg8(info, CCR, 0x69);
  
  	msc_set_vcr(info);
  
  	/* SCR (serial control)
  	 *
  	 * 15  1=tx req on FIFO half empty
  	 * 14  1=rx req on FIFO half full
  	 * 13  tx data  IRQ enable
  	 * 12  tx idle  IRQ enable
  	 * 11  rx break on IRQ enable
  	 * 10  rx data  IRQ enable
  	 * 09  rx break off IRQ enable
  	 * 08  overrun  IRQ enable
  	 * 07  DSR      IRQ enable
  	 * 06  CTS      IRQ enable
  	 * 05  DCD      IRQ enable
  	 * 04  RI       IRQ enable
  	 * 03  0=16x sampling, 1=8x sampling
  	 * 02  1=txd->rxd internal loopback enable
  	 * 01  reserved, must be zero
  	 * 00  1=master IRQ enable
  	 */
  	val = BIT15 + BIT14 + BIT0;
  	/* JCR[8] : 1 = x8 async mode feature available */
  	if ((rd_reg32(info, JCR) & BIT8) && info->params.data_rate &&
  	    ((info->base_clock < (info->params.data_rate * 16)) ||
  	     (info->base_clock % (info->params.data_rate * 16)))) {
  		/* use 8x sampling */
  		val |= BIT3;
  		set_rate(info, info->params.data_rate * 8);
  	} else {
  		/* use 16x sampling */
  		set_rate(info, info->params.data_rate * 16);
  	}
  	wr_reg16(info, SCR, val);
  
  	slgt_irq_on(info, IRQ_RXBREAK | IRQ_RXOVER);
  
  	if (info->params.loopback)
  		enable_loopback(info);
  }
  
  static void sync_mode(struct slgt_info *info)
  {
  	unsigned short val;
  
  	slgt_irq_off(info, IRQ_ALL | IRQ_MASTER);
  	tx_stop(info);
  	rx_stop(info);
  
  	/* TCR (tx control)
  	 *
  	 * 15..13  mode
  	 *         000=HDLC/SDLC
  	 *         001=raw bit synchronous
  	 *         010=asynchronous/isochronous
  	 *         011=monosync byte synchronous
  	 *         100=bisync byte synchronous
  	 *         101=xsync byte synchronous
  	 * 12..10  encoding
  	 * 09      CRC enable
  	 * 08      CRC32
  	 * 07      1=RTS driver control
  	 * 06      preamble enable
  	 * 05..04  preamble length
  	 * 03      share open/close flag
  	 * 02      reset
  	 * 01      enable
  	 * 00      auto-CTS enable
  	 */
  	val = BIT2;
  
  	switch(info->params.mode) {
  	case MGSL_MODE_XSYNC:
  		val |= BIT15 + BIT13;
  		break;
  	case MGSL_MODE_MONOSYNC: val |= BIT14 + BIT13; break;
  	case MGSL_MODE_BISYNC:   val |= BIT15; break;
  	case MGSL_MODE_RAW:      val |= BIT13; break;
  	}
  	if (info->if_mode & MGSL_INTERFACE_RTS_EN)
  		val |= BIT7;
  
  	switch(info->params.encoding)
  	{
  	case HDLC_ENCODING_NRZB:          val |= BIT10; break;
  	case HDLC_ENCODING_NRZI_MARK:     val |= BIT11; break;
  	case HDLC_ENCODING_NRZI:          val |= BIT11 + BIT10; break;
  	case HDLC_ENCODING_BIPHASE_MARK:  val |= BIT12; break;
  	case HDLC_ENCODING_BIPHASE_SPACE: val |= BIT12 + BIT10; break;
  	case HDLC_ENCODING_BIPHASE_LEVEL: val |= BIT12 + BIT11; break;
  	case HDLC_ENCODING_DIFF_BIPHASE_LEVEL: val |= BIT12 + BIT11 + BIT10; break;
  	}
  
  	switch (info->params.crc_type & HDLC_CRC_MASK)
  	{
  	case HDLC_CRC_16_CCITT: val |= BIT9; break;
  	case HDLC_CRC_32_CCITT: val |= BIT9 + BIT8; break;
  	}
  
  	if (info->params.preamble != HDLC_PREAMBLE_PATTERN_NONE)
  		val |= BIT6;
  
  	switch (info->params.preamble_length)
  	{
  	case HDLC_PREAMBLE_LENGTH_16BITS: val |= BIT5; break;
  	case HDLC_PREAMBLE_LENGTH_32BITS: val |= BIT4; break;
  	case HDLC_PREAMBLE_LENGTH_64BITS: val |= BIT5 + BIT4; break;
  	}
  
  	if (info->params.flags & HDLC_FLAG_AUTO_CTS)
  		val |= BIT0;
  
  	wr_reg16(info, TCR, val);
  
  	/* TPR (transmit preamble) */
  
  	switch (info->params.preamble)
  	{
  	case HDLC_PREAMBLE_PATTERN_FLAGS: val = 0x7e; break;
  	case HDLC_PREAMBLE_PATTERN_ONES:  val = 0xff; break;
  	case HDLC_PREAMBLE_PATTERN_ZEROS: val = 0x00; break;
  	case HDLC_PREAMBLE_PATTERN_10:    val = 0x55; break;
  	case HDLC_PREAMBLE_PATTERN_01:    val = 0xaa; break;
  	default:                          val = 0x7e; break;
  	}
  	wr_reg8(info, TPR, (unsigned char)val);
  
  	/* RCR (rx control)
  	 *
  	 * 15..13  mode
  	 *         000=HDLC/SDLC
  	 *         001=raw bit synchronous
  	 *         010=asynchronous/isochronous
  	 *         011=monosync byte synchronous
  	 *         100=bisync byte synchronous
  	 *         101=xsync byte synchronous
  	 * 12..10  encoding
  	 * 09      CRC enable
  	 * 08      CRC32
  	 * 07..03  reserved, must be 0
  	 * 02      reset
  	 * 01      enable
  	 * 00      auto-DCD enable
  	 */
  	val = 0;
  
  	switch(info->params.mode) {
  	case MGSL_MODE_XSYNC:
  		val |= BIT15 + BIT13;
  		break;
  	case MGSL_MODE_MONOSYNC: val |= BIT14 + BIT13; break;
  	case MGSL_MODE_BISYNC:   val |= BIT15; break;
  	case MGSL_MODE_RAW:      val |= BIT13; break;
  	}
  
  	switch(info->params.encoding)
  	{
  	case HDLC_ENCODING_NRZB:          val |= BIT10; break;
  	case HDLC_ENCODING_NRZI_MARK:     val |= BIT11; break;
  	case HDLC_ENCODING_NRZI:          val |= BIT11 + BIT10; break;
  	case HDLC_ENCODING_BIPHASE_MARK:  val |= BIT12; break;
  	case HDLC_ENCODING_BIPHASE_SPACE: val |= BIT12 + BIT10; break;
  	case HDLC_ENCODING_BIPHASE_LEVEL: val |= BIT12 + BIT11; break;
  	case HDLC_ENCODING_DIFF_BIPHASE_LEVEL: val |= BIT12 + BIT11 + BIT10; break;
  	}
  
  	switch (info->params.crc_type & HDLC_CRC_MASK)
  	{
  	case HDLC_CRC_16_CCITT: val |= BIT9; break;
  	case HDLC_CRC_32_CCITT: val |= BIT9 + BIT8; break;
  	}
  
  	if (info->params.flags & HDLC_FLAG_AUTO_DCD)
  		val |= BIT0;
  
  	wr_reg16(info, RCR, val);
  
  	/* CCR (clock control)
  	 *
  	 * 07..05  tx clock source
  	 * 04..02  rx clock source
  	 * 01      auxclk enable
  	 * 00      BRG enable
  	 */
  	val = 0;
  
  	if (info->params.flags & HDLC_FLAG_TXC_BRG)
  	{
  		// when RxC source is DPLL, BRG generates 16X DPLL
  		// reference clock, so take TxC from BRG/16 to get
  		// transmit clock at actual data rate
  		if (info->params.flags & HDLC_FLAG_RXC_DPLL)
  			val |= BIT6 + BIT5;	/* 011, txclk = BRG/16 */
  		else
  			val |= BIT6;	/* 010, txclk = BRG */
  	}
  	else if (info->params.flags & HDLC_FLAG_TXC_DPLL)
  		val |= BIT7;	/* 100, txclk = DPLL Input */
  	else if (info->params.flags & HDLC_FLAG_TXC_RXCPIN)
  		val |= BIT5;	/* 001, txclk = RXC Input */
  
  	if (info->params.flags & HDLC_FLAG_RXC_BRG)
  		val |= BIT3;	/* 010, rxclk = BRG */
  	else if (info->params.flags & HDLC_FLAG_RXC_DPLL)
  		val |= BIT4;	/* 100, rxclk = DPLL */
  	else if (info->params.flags & HDLC_FLAG_RXC_TXCPIN)
  		val |= BIT2;	/* 001, rxclk = TXC Input */
  
  	if (info->params.clock_speed)
  		val |= BIT1 + BIT0;
  
  	wr_reg8(info, CCR, (unsigned char)val);
  
  	if (info->params.flags & (HDLC_FLAG_TXC_DPLL + HDLC_FLAG_RXC_DPLL))
  	{
  		// program DPLL mode
  		switch(info->params.encoding)
  		{
  		case HDLC_ENCODING_BIPHASE_MARK:
  		case HDLC_ENCODING_BIPHASE_SPACE:
  			val = BIT7; break;
  		case HDLC_ENCODING_BIPHASE_LEVEL:
  		case HDLC_ENCODING_DIFF_BIPHASE_LEVEL:
  			val = BIT7 + BIT6; break;
  		default: val = BIT6;	// NRZ encodings
  		}
  		wr_reg16(info, RCR, (unsigned short)(rd_reg16(info, RCR) | val));
  
  		// DPLL requires a 16X reference clock from BRG
  		set_rate(info, info->params.clock_speed * 16);
  	}
  	else
  		set_rate(info, info->params.clock_speed);
  
  	tx_set_idle(info);
  
  	msc_set_vcr(info);
  
  	/* SCR (serial control)
  	 *
  	 * 15  1=tx req on FIFO half empty
  	 * 14  1=rx req on FIFO half full
  	 * 13  tx data  IRQ enable
  	 * 12  tx idle  IRQ enable
  	 * 11  underrun IRQ enable
  	 * 10  rx data  IRQ enable
  	 * 09  rx idle  IRQ enable
  	 * 08  overrun  IRQ enable
  	 * 07  DSR      IRQ enable
  	 * 06  CTS      IRQ enable
  	 * 05  DCD      IRQ enable
  	 * 04  RI       IRQ enable
  	 * 03  reserved, must be zero
  	 * 02  1=txd->rxd internal loopback enable
  	 * 01  reserved, must be zero
  	 * 00  1=master IRQ enable
  	 */
  	wr_reg16(info, SCR, BIT15 + BIT14 + BIT0);
  
  	if (info->params.loopback)
  		enable_loopback(info);
  }
  
  /*
   *  set transmit idle mode
   */
  static void tx_set_idle(struct slgt_info *info)
  {
  	unsigned char val;
  	unsigned short tcr;
  
  	/* if preamble enabled (tcr[6] == 1) then tx idle size = 8 bits
  	 * else tcr[5:4] = tx idle size: 00 = 8 bits, 01 = 16 bits
  	 */
  	tcr = rd_reg16(info, TCR);
  	if (info->idle_mode & HDLC_TXIDLE_CUSTOM_16) {
  		/* disable preamble, set idle size to 16 bits */
  		tcr = (tcr & ~(BIT6 + BIT5)) | BIT4;
  		/* MSB of 16 bit idle specified in tx preamble register (TPR) */
  		wr_reg8(info, TPR, (unsigned char)((info->idle_mode >> 8) & 0xff));
  	} else if (!(tcr & BIT6)) {
  		/* preamble is disabled, set idle size to 8 bits */
  		tcr &= ~(BIT5 + BIT4);
  	}
  	wr_reg16(info, TCR, tcr);
  
  	if (info->idle_mode & (HDLC_TXIDLE_CUSTOM_8 | HDLC_TXIDLE_CUSTOM_16)) {
  		/* LSB of custom tx idle specified in tx idle register */
  		val = (unsigned char)(info->idle_mode & 0xff);
  	} else {
  		/* standard 8 bit idle patterns */
  		switch(info->idle_mode)
  		{
  		case HDLC_TXIDLE_FLAGS:          val = 0x7e; break;
  		case HDLC_TXIDLE_ALT_ZEROS_ONES:
  		case HDLC_TXIDLE_ALT_MARK_SPACE: val = 0xaa; break;
  		case HDLC_TXIDLE_ZEROS:
  		case HDLC_TXIDLE_SPACE:          val = 0x00; break;
  		default:                         val = 0xff;
  		}
  	}
  
  	wr_reg8(info, TIR, val);
  }
  
  /*
   * get state of V24 status (input) signals
   */
  static void get_signals(struct slgt_info *info)
  {
  	unsigned short status = rd_reg16(info, SSR);
  
  	/* clear all serial signals except RTS and DTR */
  	info->signals &= SerialSignal_RTS | SerialSignal_DTR;
  
  	if (status & BIT3)
  		info->signals |= SerialSignal_DSR;
  	if (status & BIT2)
  		info->signals |= SerialSignal_CTS;
  	if (status & BIT1)
  		info->signals |= SerialSignal_DCD;
  	if (status & BIT0)
  		info->signals |= SerialSignal_RI;
  }
  
  /*
   * set V.24 Control Register based on current configuration
   */
  static void msc_set_vcr(struct slgt_info *info)
  {
  	unsigned char val = 0;
  
  	/* VCR (V.24 control)
  	 *
  	 * 07..04  serial IF select
  	 * 03      DTR
  	 * 02      RTS
  	 * 01      LL
  	 * 00      RL
  	 */
  
  	switch(info->if_mode & MGSL_INTERFACE_MASK)
  	{
  	case MGSL_INTERFACE_RS232:
  		val |= BIT5; /* 0010 */
  		break;
  	case MGSL_INTERFACE_V35:
  		val |= BIT7 + BIT6 + BIT5; /* 1110 */
  		break;
  	case MGSL_INTERFACE_RS422:
  		val |= BIT6; /* 0100 */
  		break;
  	}
  
  	if (info->if_mode & MGSL_INTERFACE_MSB_FIRST)
  		val |= BIT4;
  	if (info->signals & SerialSignal_DTR)
  		val |= BIT3;
  	if (info->signals & SerialSignal_RTS)
  		val |= BIT2;
  	if (info->if_mode & MGSL_INTERFACE_LL)
  		val |= BIT1;
  	if (info->if_mode & MGSL_INTERFACE_RL)
  		val |= BIT0;
  	wr_reg8(info, VCR, val);
  }
  
  /*
   * set state of V24 control (output) signals
   */
  static void set_signals(struct slgt_info *info)
  {
  	unsigned char val = rd_reg8(info, VCR);
  	if (info->signals & SerialSignal_DTR)
  		val |= BIT3;
  	else
  		val &= ~BIT3;
  	if (info->signals & SerialSignal_RTS)
  		val |= BIT2;
  	else
  		val &= ~BIT2;
  	wr_reg8(info, VCR, val);
  }
  
  /*
   * free range of receive DMA buffers (i to last)
   */
  static void free_rbufs(struct slgt_info *info, unsigned int i, unsigned int last)
  {
  	int done = 0;
  
  	while(!done) {
  		/* reset current buffer for reuse */
  		info->rbufs[i].status = 0;
  		set_desc_count(info->rbufs[i], info->rbuf_fill_level);
  		if (i == last)
  			done = 1;
  		if (++i == info->rbuf_count)
  			i = 0;
  	}
  	info->rbuf_current = i;
  }
  
  /*
   * mark all receive DMA buffers as free
   */
  static void reset_rbufs(struct slgt_info *info)
  {
  	free_rbufs(info, 0, info->rbuf_count - 1);
  	info->rbuf_fill_index = 0;
  	info->rbuf_fill_count = 0;
  }
  
  /*
   * pass receive HDLC frame to upper layer
   *
   * return true if frame available, otherwise false
   */
  static bool rx_get_frame(struct slgt_info *info)
  {
  	unsigned int start, end;
  	unsigned short status;
  	unsigned int framesize = 0;
  	unsigned long flags;
  	struct tty_struct *tty = info->port.tty;
  	unsigned char addr_field = 0xff;
  	unsigned int crc_size = 0;
  
  	switch (info->params.crc_type & HDLC_CRC_MASK) {
  	case HDLC_CRC_16_CCITT: crc_size = 2; break;
  	case HDLC_CRC_32_CCITT: crc_size = 4; break;
  	}
  
  check_again:
  
  	framesize = 0;
  	addr_field = 0xff;
  	start = end = info->rbuf_current;
  
  	for (;;) {
  		if (!desc_complete(info->rbufs[end]))
  			goto cleanup;
  
  		if (framesize == 0 && info->params.addr_filter != 0xff)
  			addr_field = info->rbufs[end].buf[0];
  
  		framesize += desc_count(info->rbufs[end]);
  
  		if (desc_eof(info->rbufs[end]))
  			break;
  
  		if (++end == info->rbuf_count)
  			end = 0;
  
  		if (end == info->rbuf_current) {
  			if (info->rx_enabled){
  				spin_lock_irqsave(&info->lock,flags);
  				rx_start(info);
  				spin_unlock_irqrestore(&info->lock,flags);
  			}
  			goto cleanup;
  		}
  	}
  
  	/* status
  	 *
  	 * 15      buffer complete
  	 * 14..06  reserved
  	 * 05..04  residue
  	 * 02      eof (end of frame)
  	 * 01      CRC error
  	 * 00      abort
  	 */
  	status = desc_status(info->rbufs[end]);
  
  	/* ignore CRC bit if not using CRC (bit is undefined) */
  	if ((info->params.crc_type & HDLC_CRC_MASK) == HDLC_CRC_NONE)
  		status &= ~BIT1;
  
  	if (framesize == 0 ||
  		 (addr_field != 0xff && addr_field != info->params.addr_filter)) {
  		free_rbufs(info, start, end);
  		goto check_again;
  	}
  
  	if (framesize < (2 + crc_size) || status & BIT0) {
  		info->icount.rxshort++;
  		framesize = 0;
  	} else if (status & BIT1) {
  		info->icount.rxcrc++;
  		if (!(info->params.crc_type & HDLC_CRC_RETURN_EX))
  			framesize = 0;
  	}
  
  #if SYNCLINK_GENERIC_HDLC
  	if (framesize == 0) {
  		info->netdev->stats.rx_errors++;
  		info->netdev->stats.rx_frame_errors++;
  	}
  #endif
  
  	DBGBH(("%s rx frame status=%04X size=%d\n",
  		info->device_name, status, framesize));
  	DBGDATA(info, info->rbufs[start].buf, min_t(int, framesize, info->rbuf_fill_level), "rx");
  
  	if (framesize) {
  		if (!(info->params.crc_type & HDLC_CRC_RETURN_EX)) {
  			framesize -= crc_size;
  			crc_size = 0;
  		}
  
  		if (framesize > info->max_frame_size + crc_size)
  			info->icount.rxlong++;
  		else {
  			/* copy dma buffer(s) to contiguous temp buffer */
  			int copy_count = framesize;
  			int i = start;
  			unsigned char *p = info->tmp_rbuf;
  			info->tmp_rbuf_count = framesize;
  
  			info->icount.rxok++;
  
  			while(copy_count) {
  				int partial_count = min_t(int, copy_count, info->rbuf_fill_level);
  				memcpy(p, info->rbufs[i].buf, partial_count);
  				p += partial_count;
  				copy_count -= partial_count;
  				if (++i == info->rbuf_count)
  					i = 0;
  			}
  
  			if (info->params.crc_type & HDLC_CRC_RETURN_EX) {
  				*p = (status & BIT1) ? RX_CRC_ERROR : RX_OK;
  				framesize++;
  			}
  
  #if SYNCLINK_GENERIC_HDLC
  			if (info->netcount)
  				hdlcdev_rx(info,info->tmp_rbuf, framesize);
  			else
  #endif
  				ldisc_receive_buf(tty, info->tmp_rbuf, info->flag_buf, framesize);
  		}
  	}
  	free_rbufs(info, start, end);
  	return true;
  
  cleanup:
  	return false;
  }
  
  /*
   * pass receive buffer (RAW synchronous mode) to tty layer
   * return true if buffer available, otherwise false
   */
  static bool rx_get_buf(struct slgt_info *info)
  {
  	unsigned int i = info->rbuf_current;
  	unsigned int count;
  
  	if (!desc_complete(info->rbufs[i]))
  		return false;
  	count = desc_count(info->rbufs[i]);
  	switch(info->params.mode) {
  	case MGSL_MODE_MONOSYNC:
  	case MGSL_MODE_BISYNC:
  	case MGSL_MODE_XSYNC:
  		/* ignore residue in byte synchronous modes */
  		if (desc_residue(info->rbufs[i]))
  			count--;
  		break;
  	}
  	DBGDATA(info, info->rbufs[i].buf, count, "rx");
  	DBGINFO(("rx_get_buf size=%d\n", count));
  	if (count)
  		ldisc_receive_buf(info->port.tty, info->rbufs[i].buf,
  				  info->flag_buf, count);
  	free_rbufs(info, i, i);
  	return true;
  }
  
  static void reset_tbufs(struct slgt_info *info)
  {
  	unsigned int i;
  	info->tbuf_current = 0;
  	for (i=0 ; i < info->tbuf_count ; i++) {
  		info->tbufs[i].status = 0;
  		info->tbufs[i].count  = 0;
  	}
  }
  
  /*
   * return number of free transmit DMA buffers
   */
  static unsigned int free_tbuf_count(struct slgt_info *info)
  {
  	unsigned int count = 0;
  	unsigned int i = info->tbuf_current;
  
  	do
  	{
  		if (desc_count(info->tbufs[i]))
  			break; /* buffer in use */
  		++count;
  		if (++i == info->tbuf_count)
  			i=0;
  	} while (i != info->tbuf_current);
  
  	/* if tx DMA active, last zero count buffer is in use */
  	if (count && (rd_reg32(info, TDCSR) & BIT0))
  		--count;
  
  	return count;
  }
  
  /*
   * return number of bytes in unsent transmit DMA buffers
   * and the serial controller tx FIFO
   */
  static unsigned int tbuf_bytes(struct slgt_info *info)
  {
  	unsigned int total_count = 0;
  	unsigned int i = info->tbuf_current;
  	unsigned int reg_value;
  	unsigned int count;
  	unsigned int active_buf_count = 0;
  
  	/*
  	 * Add descriptor counts for all tx DMA buffers.
  	 * If count is zero (cleared by DMA controller after read),
  	 * the buffer is complete or is actively being read from.
  	 *
  	 * Record buf_count of last buffer with zero count starting
  	 * from current ring position. buf_count is mirror
  	 * copy of count and is not cleared by serial controller.
  	 * If DMA controller is active, that buffer is actively
  	 * being read so add to total.
  	 */
  	do {
  		count = desc_count(info->tbufs[i]);
  		if (count)
  			total_count += count;
  		else if (!total_count)
  			active_buf_count = info->tbufs[i].buf_count;
  		if (++i == info->tbuf_count)
  			i = 0;
  	} while (i != info->tbuf_current);
  
  	/* read tx DMA status register */
  	reg_value = rd_reg32(info, TDCSR);
  
  	/* if tx DMA active, last zero count buffer is in use */
  	if (reg_value & BIT0)
  		total_count += active_buf_count;
  
  	/* add tx FIFO count = reg_value[15..8] */
  	total_count += (reg_value >> 8) & 0xff;
  
  	/* if transmitter active add one byte for shift register */
  	if (info->tx_active)
  		total_count++;
  
  	return total_count;
  }
  
  /*
   * load data into transmit DMA buffer ring and start transmitter if needed
   * return true if data accepted, otherwise false (buffers full)
   */
  static bool tx_load(struct slgt_info *info, const char *buf, unsigned int size)
  {
  	unsigned short count;
  	unsigned int i;
  	struct slgt_desc *d;
  
  	/* check required buffer space */
  	if (DIV_ROUND_UP(size, DMABUFSIZE) > free_tbuf_count(info))
  		return false;
  
  	DBGDATA(info, buf, size, "tx");
  
  	/*
  	 * copy data to one or more DMA buffers in circular ring
  	 * tbuf_start   = first buffer for this data
  	 * tbuf_current = next free buffer
  	 *
  	 * Copy all data before making data visible to DMA controller by
  	 * setting descriptor count of the first buffer.
  	 * This prevents an active DMA controller from reading the first DMA
  	 * buffers of a frame and stopping before the final buffers are filled.
  	 */
  
  	info->tbuf_start = i = info->tbuf_current;
  
  	while (size) {
  		d = &info->tbufs[i];
  
  		count = (unsigned short)((size > DMABUFSIZE) ? DMABUFSIZE : size);
  		memcpy(d->buf, buf, count);
  
  		size -= count;
  		buf  += count;
  
  		/*
  		 * set EOF bit for last buffer of HDLC frame or
  		 * for every buffer in raw mode
  		 */
  		if ((!size && info->params.mode == MGSL_MODE_HDLC) ||
  		    info->params.mode == MGSL_MODE_RAW)
  			set_desc_eof(*d, 1);
  		else
  			set_desc_eof(*d, 0);
  
  		/* set descriptor count for all but first buffer */
  		if (i != info->tbuf_start)
  			set_desc_count(*d, count);
  		d->buf_count = count;
  
  		if (++i == info->tbuf_count)
  			i = 0;
  	}
  
  	info->tbuf_current = i;
  
  	/* set first buffer count to make new data visible to DMA controller */
  	d = &info->tbufs[info->tbuf_start];
  	set_desc_count(*d, d->buf_count);
  
  	/* start transmitter if needed and update transmit timeout */
  	if (!info->tx_active)
  		tx_start(info);
  	update_tx_timer(info);
  
  	return true;
  }
  
  static int register_test(struct slgt_info *info)
  {
  	static unsigned short patterns[] =
  		{0x0000, 0xffff, 0xaaaa, 0x5555, 0x6969, 0x9696};
  	static unsigned int count = ARRAY_SIZE(patterns);
  	unsigned int i;
  	int rc = 0;
  
  	for (i=0 ; i < count ; i++) {
  		wr_reg16(info, TIR, patterns[i]);
  		wr_reg16(info, BDR, patterns[(i+1)%count]);
  		if ((rd_reg16(info, TIR) != patterns[i]) ||
  		    (rd_reg16(info, BDR) != patterns[(i+1)%count])) {
  			rc = -ENODEV;
  			break;
  		}
  	}
  	info->gpio_present = (rd_reg32(info, JCR) & BIT5) ? 1 : 0;
  	info->init_error = rc ? 0 : DiagStatus_AddressFailure;
  	return rc;
  }
  
  static int irq_test(struct slgt_info *info)
  {
  	unsigned long timeout;
  	unsigned long flags;
  	struct tty_struct *oldtty = info->port.tty;
  	u32 speed = info->params.data_rate;
  
  	info->params.data_rate = 921600;
  	info->port.tty = NULL;
  
  	spin_lock_irqsave(&info->lock, flags);
  	async_mode(info);
  	slgt_irq_on(info, IRQ_TXIDLE);
  
  	/* enable transmitter */
  	wr_reg16(info, TCR,
  		(unsigned short)(rd_reg16(info, TCR) | BIT1));
  
  	/* write one byte and wait for tx idle */
  	wr_reg16(info, TDR, 0);
  
  	/* assume failure */
  	info->init_error = DiagStatus_IrqFailure;
  	info->irq_occurred = false;
  
  	spin_unlock_irqrestore(&info->lock, flags);
  
  	timeout=100;
  	while(timeout-- && !info->irq_occurred)
  		msleep_interruptible(10);
  
  	spin_lock_irqsave(&info->lock,flags);
  	reset_port(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	info->params.data_rate = speed;
  	info->port.tty = oldtty;
  
  	info->init_error = info->irq_occurred ? 0 : DiagStatus_IrqFailure;
  	return info->irq_occurred ? 0 : -ENODEV;
  }
  
  static int loopback_test_rx(struct slgt_info *info)
  {
  	unsigned char *src, *dest;
  	int count;
  
  	if (desc_complete(info->rbufs[0])) {
  		count = desc_count(info->rbufs[0]);
  		src   = info->rbufs[0].buf;
  		dest  = info->tmp_rbuf;
  
  		for( ; count ; count-=2, src+=2) {
  			/* src=data byte (src+1)=status byte */
  			if (!(*(src+1) & (BIT9 + BIT8))) {
  				*dest = *src;
  				dest++;
  				info->tmp_rbuf_count++;
  			}
  		}
  		DBGDATA(info, info->tmp_rbuf, info->tmp_rbuf_count, "rx");
  		return 1;
  	}
  	return 0;
  }
  
  static int loopback_test(struct slgt_info *info)
  {
  #define TESTFRAMESIZE 20
  
  	unsigned long timeout;
  	u16 count = TESTFRAMESIZE;
  	unsigned char buf[TESTFRAMESIZE];
  	int rc = -ENODEV;
  	unsigned long flags;
  
  	struct tty_struct *oldtty = info->port.tty;
  	MGSL_PARAMS params;
  
  	memcpy(&params, &info->params, sizeof(params));
  
  	info->params.mode = MGSL_MODE_ASYNC;
  	info->params.data_rate = 921600;
  	info->params.loopback = 1;
  	info->port.tty = NULL;
  
  	/* build and send transmit frame */
  	for (count = 0; count < TESTFRAMESIZE; ++count)
  		buf[count] = (unsigned char)count;
  
  	info->tmp_rbuf_count = 0;
  	memset(info->tmp_rbuf, 0, TESTFRAMESIZE);
  
  	/* program hardware for HDLC and enabled receiver */
  	spin_lock_irqsave(&info->lock,flags);
  	async_mode(info);
  	rx_start(info);
  	tx_load(info, buf, count);
  	spin_unlock_irqrestore(&info->lock, flags);
  
  	/* wait for receive complete */
  	for (timeout = 100; timeout; --timeout) {
  		msleep_interruptible(10);
  		if (loopback_test_rx(info)) {
  			rc = 0;
  			break;
  		}
  	}
  
  	/* verify received frame length and contents */
  	if (!rc && (info->tmp_rbuf_count != count ||
  		  memcmp(buf, info->tmp_rbuf, count))) {
  		rc = -ENODEV;
  	}
  
  	spin_lock_irqsave(&info->lock,flags);
  	reset_adapter(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  	memcpy(&info->params, &params, sizeof(info->params));
  	info->port.tty = oldtty;
  
  	info->init_error = rc ? DiagStatus_DmaFailure : 0;
  	return rc;
  }
  
  static int adapter_test(struct slgt_info *info)
  {
  	DBGINFO(("testing %s\n", info->device_name));
  	if (register_test(info) < 0) {
  		printk("register test failure %s addr=%08X\n",
  			info->device_name, info->phys_reg_addr);
  	} else if (irq_test(info) < 0) {
  		printk("IRQ test failure %s IRQ=%d\n",
  			info->device_name, info->irq_level);
  	} else if (loopback_test(info) < 0) {
  		printk("loopback test failure %s\n", info->device_name);
  	}
  	return info->init_error;
  }
  
  /*
   * transmit timeout handler
   */
  static void tx_timeout(struct timer_list *t)
  {
  	struct slgt_info *info = from_timer(info, t, tx_timer);
  	unsigned long flags;
  
  	DBGINFO(("%s tx_timeout\n", info->device_name));
  	if(info->tx_active && info->params.mode == MGSL_MODE_HDLC) {
  		info->icount.txtimeout++;
  	}
  	spin_lock_irqsave(&info->lock,flags);
  	tx_stop(info);
  	spin_unlock_irqrestore(&info->lock,flags);
  
  #if SYNCLINK_GENERIC_HDLC
  	if (info->netcount)
  		hdlcdev_tx_done(info);
  	else
  #endif
  		bh_transmit(info);
  }
  
  /*
   * receive buffer polling timer
   */
  static void rx_timeout(struct timer_list *t)
  {
  	struct slgt_info *info = from_timer(info, t, rx_timer);
  	unsigned long flags;
  
  	DBGINFO(("%s rx_timeout\n", info->device_name));
  	spin_lock_irqsave(&info->lock, flags);
  	info->pending_bh |= BH_RECEIVE;
  	spin_unlock_irqrestore(&info->lock, flags);
  	bh_handler(&info->task);
  }
  
  