text: /*
   *  Driver for GRLIB serial ports (APBUART)
   *
   *  Based on linux/drivers/serial/amba.c
   *
   *  Copyright (C) 2000 Deep Blue Solutions Ltd.
   *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
   *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
   *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
   *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
   */
  
  #if defined(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
  #define SUPPORT_SYSRQ
  #endif
  
  #include <linux/module.h>
  #include <linux/tty.h>
  #include <linux/ioport.h>
  #include <linux/init.h>
  #include <linux/serial.h>
  #include <linux/console.h>
  #include <linux/sysrq.h>
  #include <linux/kthread.h>
  #include <linux/device.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/of_platform.h>
  #include <linux/of_irq.h>
  #include <linux/platform_device.h>
  #include <linux/io.h>
  #include <linux/serial_core.h>
  #include <asm/irq.h>
  
  #include "apbuart.h"
  
  #define SERIAL_APBUART_MAJOR	TTY_MAJOR
  #define SERIAL_APBUART_MINOR	64
  #define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
  
  static void apbuart_tx_chars(struct uart_port *port);
  
  static void apbuart_stop_tx(struct uart_port *port)
  {
  	unsigned int cr;
  
  	cr = UART_GET_CTRL(port);
  	cr &= ~UART_CTRL_TI;
  	UART_PUT_CTRL(port, cr);
  }
  
  static void apbuart_start_tx(struct uart_port *port)
  {
  	unsigned int cr;
  
  	cr = UART_GET_CTRL(port);
  	cr |= UART_CTRL_TI;
  	UART_PUT_CTRL(port, cr);
  
  	if (UART_GET_STATUS(port) & UART_STATUS_THE)
  		apbuart_tx_chars(port);
  }
  
  static void apbuart_stop_rx(struct uart_port *port)
  {
  	unsigned int cr;
  
  	cr = UART_GET_CTRL(port);
  	cr &= ~(UART_CTRL_RI);
  	UART_PUT_CTRL(port, cr);
  }
  
  static void apbuart_enable_ms(struct uart_port *port)
  {
  	/* No modem status change interrupts for APBUART */
  }
  
  static void apbuart_rx_chars(struct uart_port *port)
  {
  	struct tty_struct *tty = port->state->port.tty;
  	unsigned int status, ch, rsr, flag;
  	unsigned int max_chars = port->fifosize;
  
  	status = UART_GET_STATUS(port);
  
  	while (UART_RX_DATA(status) && (max_chars--)) {
  
  		ch = UART_GET_CHAR(port);
  		flag = TTY_NORMAL;
  
  		port->icount.rx++;
  
  		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
  		UART_PUT_STATUS(port, 0);
  		if (rsr & UART_STATUS_ERR) {
  
  			if (rsr & UART_STATUS_BR) {
  				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
  				port->icount.brk++;
  				if (uart_handle_break(port))
  					goto ignore_char;
  			} else if (rsr & UART_STATUS_PE) {
  				port->icount.parity++;
  			} else if (rsr & UART_STATUS_FE) {
  				port->icount.frame++;
  			}
  			if (rsr & UART_STATUS_OE)
  				port->icount.overrun++;
  
  			rsr &= port->read_status_mask;
  
  			if (rsr & UART_STATUS_PE)
  				flag = TTY_PARITY;
  			else if (rsr & UART_STATUS_FE)
  				flag = TTY_FRAME;
  		}
  
  		if (uart_handle_sysrq_char(port, ch))
  			goto ignore_char;
  
  		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
  
  	      ignore_char:
  		status = UART_GET_STATUS(port);
  	}
  
  	tty_flip_buffer_push(tty);
  }
  
  static void apbuart_tx_chars(struct uart_port *port)
  {
  	struct circ_buf *xmit = &port->state->xmit;
  	int count;
  
  	if (port->x_char) {
  		UART_PUT_CHAR(port, port->x_char);
  		port->icount.tx++;
  		port->x_char = 0;
  		return;
  	}
  
  	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
  		apbuart_stop_tx(port);
  		return;
  	}
  
  	/* amba: fill FIFO */
  	count = port->fifosize >> 1;
  	do {
  		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
  		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
  		port->icount.tx++;
  		if (uart_circ_empty(xmit))
  			break;
  	} while (--count > 0);
  
  	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  		uart_write_wakeup(port);
  
  	if (uart_circ_empty(xmit))
  		apbuart_stop_tx(port);
  }
  
  static irqreturn_t apbuart_int(int irq, void *dev_id)
  {
  	struct uart_port *port = dev_id;
  	unsigned int status;
  
  	spin_lock(&port->lock);
  
  	status = UART_GET_STATUS(port);
  	if (status & UART_STATUS_DR)
  		apbuart_rx_chars(port);
  	if (status & UART_STATUS_THE)
  		apbuart_tx_chars(port);
  
  	spin_unlock(&port->lock);
  
  	return IRQ_HANDLED;
  }
  
  static unsigned int apbuart_tx_empty(struct uart_port *port)
  {
  	unsigned int status = UART_GET_STATUS(port);
  	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
  }
  
  static unsigned int apbuart_get_mctrl(struct uart_port *port)
  {
  	/* The GRLIB APBUART handles flow control in hardware */
  	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
  }
  
  static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
  {
  	/* The GRLIB APBUART handles flow control in hardware */
  }
  
  static void apbuart_break_ctl(struct uart_port *port, int break_state)
  {
  	/* We don't support sending break */
  }
  
  static int apbuart_startup(struct uart_port *port)
  {
  	int retval;
  	unsigned int cr;
  
  	/* Allocate the IRQ */
  	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
  	if (retval)
  		return retval;
  
  	/* Finally, enable interrupts */
  	cr = UART_GET_CTRL(port);
  	UART_PUT_CTRL(port,
  		      cr | UART_CTRL_RE | UART_CTRL_TE |
  		      UART_CTRL_RI | UART_CTRL_TI);
  
  	return 0;
  }
  
  static void apbuart_shutdown(struct uart_port *port)
  {
  	unsigned int cr;
  
  	/* disable all interrupts, disable the port */
  	cr = UART_GET_CTRL(port);
  	UART_PUT_CTRL(port,
  		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
  			     UART_CTRL_RI | UART_CTRL_TI));
  
  	/* Free the interrupt */
  	free_irq(port->irq, port);
  }
  
  static void apbuart_set_termios(struct uart_port *port,
  				struct ktermios *termios, struct ktermios *old)
  {
  	unsigned int cr;
  	unsigned long flags;
  	unsigned int baud, quot;
  
  	/* Ask the core to calculate the divisor for us. */
  	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
  	if (baud == 0)
  		panic("invalid baudrate %i\n", port->uartclk / 16);
  
  	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
  	quot = (uart_get_divisor(port, baud)) * 2;
  	cr = UART_GET_CTRL(port);
  	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
  
  	if (termios->c_cflag & PARENB) {
  		cr |= UART_CTRL_PE;
  		if ((termios->c_cflag & PARODD))
  			cr |= UART_CTRL_PS;
  	}
  
  	/* Enable flow control. */
  	if (termios->c_cflag & CRTSCTS)
  		cr |= UART_CTRL_FL;
  
  	spin_lock_irqsave(&port->lock, flags);
  
  	/* Update the per-port timeout. */
  	uart_update_timeout(port, termios->c_cflag, baud);
  
  	port->read_status_mask = UART_STATUS_OE;
  	if (termios->c_iflag & INPCK)
  		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
  
  	/* Characters to ignore */
  	port->ignore_status_mask = 0;
  	if (termios->c_iflag & IGNPAR)
  		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
  
  	/* Ignore all characters if CREAD is not set. */
  	if ((termios->c_cflag & CREAD) == 0)
  		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
  
  	/* Set baud rate */
  	quot -= 1;
  	UART_PUT_SCAL(port, quot);
  	UART_PUT_CTRL(port, cr);
  
  	spin_unlock_irqrestore(&port->lock, flags);
  }
  
  static const char *apbuart_type(struct uart_port *port)
  {
  	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
  }
  
  static void apbuart_release_port(struct uart_port *port)
  {
  	release_mem_region(port->mapbase, 0x100);
  }
  
  static int apbuart_request_port(struct uart_port *port)
  {
  	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
  	    != NULL ? 0 : -EBUSY;
  	return 0;
  }
  
  /* Configure/autoconfigure the port */
  static void apbuart_config_port(struct uart_port *port, int flags)
  {
  	if (flags & UART_CONFIG_TYPE) {
  		port->type = PORT_APBUART;
  		apbuart_request_port(port);
  	}
  }
  
  /* Verify the new serial_struct (for TIOCSSERIAL) */
  static int apbuart_verify_port(struct uart_port *port,
  			       struct serial_struct *ser)
  {
  	int ret = 0;
  	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
  		ret = -EINVAL;
  	if (ser->irq < 0 || ser->irq >= NR_IRQS)
  		ret = -EINVAL;
  	if (ser->baud_base < 9600)
  		ret = -EINVAL;
  	return ret;
  }
  
  static struct uart_ops grlib_apbuart_ops = {
  	.tx_empty = apbuart_tx_empty,
  	.set_mctrl = apbuart_set_mctrl,
  	.get_mctrl = apbuart_get_mctrl,
  	.stop_tx = apbuart_stop_tx,
  	.start_tx = apbuart_start_tx,
  	.stop_rx = apbuart_stop_rx,
  	.enable_ms = apbuart_enable_ms,
  	.break_ctl = apbuart_break_ctl,
  	.startup = apbuart_startup,
  	.shutdown = apbuart_shutdown,
  	.set_termios = apbuart_set_termios,
  	.type = apbuart_type,
  	.release_port = apbuart_release_port,
  	.request_port = apbuart_request_port,
  	.config_port = apbuart_config_port,
  	.verify_port = apbuart_verify_port,
  };
  
  static struct uart_port grlib_apbuart_ports[UART_NR];
  static struct device_node *grlib_apbuart_nodes[UART_NR];
  
  static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
  {
  	int ctrl, loop = 0;
  	int status;
  	int fifosize;
  	unsigned long flags;
  
  	ctrl = UART_GET_CTRL(port);
  
  	/*
  	 * Enable the transceiver and wait for it to be ready to send data.
  	 * Clear interrupts so that this process will not be externally
  	 * interrupted in the middle (which can cause the transceiver to
  	 * drain prematurely).
  	 */
  
  	local_irq_save(flags);
  
  	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
  
  	while (!UART_TX_READY(UART_GET_STATUS(port)))
  		loop++;
  
  	/*
  	 * Disable the transceiver so data isn't actually sent during the
  	 * actual test.
  	 */
  
  	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
  
  	fifosize = 1;
  	UART_PUT_CHAR(port, 0);
  
  	/*
  	 * So long as transmitting a character increments the tranceivier FIFO
  	 * length the FIFO must be at least that big. These bytes will
  	 * automatically drain off of the FIFO.
  	 */
  
  	status = UART_GET_STATUS(port);
  	while (((status >> 20) & 0x3F) == fifosize) {
  		fifosize++;
  		UART_PUT_CHAR(port, 0);
  		status = UART_GET_STATUS(port);
  	}
  
  	fifosize--;
  
  	UART_PUT_CTRL(port, ctrl);
  	local_irq_restore(flags);
  
  	if (fifosize == 0)
  		fifosize = 1;
  
  	return fifosize;
  }
  
  static void apbuart_flush_fifo(struct uart_port *port)
  {
  	int i;
  
  	for (i = 0; i < port->fifosize; i++)
  		UART_GET_CHAR(port);
  }
  
  /* ======================================================================== */
  /* Console driver, if enabled                                               */
  /* ======================================================================== */
  
  #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
  
  static void apbuart_console_putchar(struct uart_port *port, int ch)
  {
  	unsigned int status;
  	do {
  		status = UART_GET_STATUS(port);
  	} while (!UART_TX_READY(status));
  	UART_PUT_CHAR(port, ch);
  }
  
  static void
  apbuart_console_write(struct console *co, const char *s, unsigned int count)
  {
  	struct uart_port *port = &grlib_apbuart_ports[co->index];
  	unsigned int status, old_cr, new_cr;
  
  	/* First save the CR then disable the interrupts */
  	old_cr = UART_GET_CTRL(port);
  	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
  	UART_PUT_CTRL(port, new_cr);
  
  	uart_console_write(port, s, count, apbuart_console_putchar);
  
  	/*
  	 *      Finally, wait for transmitter to become empty
  	 *      and restore the TCR
  	 */
  	do {
  		status = UART_GET_STATUS(port);
  	} while (!UART_TX_READY(status));
  	UART_PUT_CTRL(port, old_cr);
  }
  
  static void __init
  apbuart_console_get_options(struct uart_port *port, int *baud,
  			    int *parity, int *bits)
  {
  	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
  
  		unsigned int quot, status;
  		status = UART_GET_STATUS(port);
  
  		*parity = 'n';
  		if (status & UART_CTRL_PE) {
  			if ((status & UART_CTRL_PS) == 0)
  				*parity = 'e';
  			else
  				*parity = 'o';
  		}
  
  		*bits = 8;
  		quot = UART_GET_SCAL(port) / 8;
  		*baud = port->uartclk / (16 * (quot + 1));
  	}
  }
  
  static int __init apbuart_console_setup(struct console *co, char *options)
  {
  	struct uart_port *port;
  	int baud = 38400;
  	int bits = 8;
  	int parity = 'n';
  	int flow = 'n';
  
  	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
  		 co, co->index, options);
  
  	/*
  	 * Check whether an invalid uart number has been specified, and
  	 * if so, search for the first available port that does have
  	 * console support.
  	 */
  	if (co->index >= grlib_apbuart_port_nr)
  		co->index = 0;
  
  	port = &grlib_apbuart_ports[co->index];
  
  	spin_lock_init(&port->lock);
  
  	if (options)
  		uart_parse_options(options, &baud, &parity, &bits, &flow);
  	else
  		apbuart_console_get_options(port, &baud, &parity, &bits);
  
  	return uart_set_options(port, co, baud, parity, bits, flow);
  }
  
  static struct uart_driver grlib_apbuart_driver;
  
  static struct console grlib_apbuart_console = {
  	.name = "ttyS",
  	.write = apbuart_console_write,
  	.device = uart_console_device,
  	.setup = apbuart_console_setup,
  	.flags = CON_PRINTBUFFER,
  	.index = -1,
  	.data = &grlib_apbuart_driver,
  };
  
  static int grlib_apbuart_configure(void);
  
  static int __init apbuart_console_init(void)
  {
  	if (grlib_apbuart_configure())
  		return -ENODEV;
  	register_console(&grlib_apbuart_console);
  	return 0;
  }
  
  console_initcall(apbuart_console_init);
  
  #define APBUART_CONSOLE	(&grlib_apbuart_console)
  #else
  #define APBUART_CONSOLE	NULL
  #endif
  
  static struct uart_driver grlib_apbuart_driver = {
  	.owner = THIS_MODULE,
  	.driver_name = "serial",
  	.dev_name = "ttyS",
  	.major = SERIAL_APBUART_MAJOR,
  	.minor = SERIAL_APBUART_MINOR,
  	.nr = UART_NR,
  	.cons = APBUART_CONSOLE,
  };
  
  /* ======================================================================== */
  /* OF Platform Driver                                                       */
  /* ======================================================================== */
  
  static int __devinit apbuart_probe(struct platform_device *op)
  {
  	int i;
  	struct uart_port *port = NULL;
  
  	for (i = 0; i < grlib_apbuart_port_nr; i++) {
  		if (op->dev.of_node == grlib_apbuart_nodes[i])
  			break;
  	}
  
  	port = &grlib_apbuart_ports[i];
  	port->dev = &op->dev;
  	port->irq = op->archdata.irqs[0];
  
  	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
  
  	apbuart_flush_fifo((struct uart_port *) port);
  
  	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
  	       (unsigned long long) port->mapbase, port->irq);
  	return 0;
  }
  
  static struct of_device_id __initdata apbuart_match[] = {
  	{
  	 .name = "GAISLER_APBUART",
  	 },
  	{
  	 .name = "01_00c",
  	 },
  	{},
  };
  
  static struct platform_driver grlib_apbuart_of_driver = {
  	.probe = apbuart_probe,
  	.driver = {
  		.owner = THIS_MODULE,
  		.name = "grlib-apbuart",
  		.of_match_table = apbuart_match,
  	},
  };
  
  static int grlib_apbuart_configure(void)
  {
  	struct device_node *np;
  	int line = 0;
  
  	for_each_matching_node(np, apbuart_match) {
  		const int *ampopts;
  		const u32 *freq_hz;
  		const struct amba_prom_registers *regs;
  		struct uart_port *port;
  		unsigned long addr;
  
  		ampopts = of_get_property(np, "ampopts", NULL);
  		if (ampopts && (*ampopts == 0))
  			continue; /* Ignore if used by another OS instance */
  		regs = of_get_property(np, "reg", NULL);
  		/* Frequency of APB Bus is frequency of UART */
  		freq_hz = of_get_property(np, "freq", NULL);
  
  		if (!regs || !freq_hz || (*freq_hz == 0))
  			continue;
  
  		grlib_apbuart_nodes[line] = np;
  
  		addr = regs->phys_addr;
  
  		port = &grlib_apbuart_ports[line];
  
  		port->mapbase = addr;
  		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
  		port->irq = 0;
  		port->iotype = UPIO_MEM;
  		port->ops = &grlib_apbuart_ops;
  		port->flags = UPF_BOOT_AUTOCONF;
  		port->line = line;
  		port->uartclk = *freq_hz;
  		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
  		line++;
  
  		/* We support maximum UART_NR uarts ... */
  		if (line == UART_NR)
  			break;
  	}
  
  	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
  	return line ? 0 : -ENODEV;
  }
  
  static int __init grlib_apbuart_init(void)
  {
  	int ret;
  
  	/* Find all APBUARTS in device the tree and initialize their ports */
  	ret = grlib_apbuart_configure();
  	if (ret)
  		return ret;
  
  	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
  
  	ret = uart_register_driver(&grlib_apbuart_driver);
  
  	if (ret) {
  		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
  		       __FILE__, ret);
  		return ret;
  	}
  
  	ret = platform_driver_register(&grlib_apbuart_of_driver);
  	if (ret) {
  		printk(KERN_ERR
  		       "%s: platform_driver_register failed (%i)\n",
  		       __FILE__, ret);
  		uart_unregister_driver(&grlib_apbuart_driver);
  		return ret;
  	}
  
  	return ret;
  }
  
  static void __exit grlib_apbuart_exit(void)
  {
  	int i;
  
  	for (i = 0; i < grlib_apbuart_port_nr; i++)
  		uart_remove_one_port(&grlib_apbuart_driver,
  				     &grlib_apbuart_ports[i]);
  
  	uart_unregister_driver(&grlib_apbuart_driver);
  	platform_driver_unregister(&grlib_apbuart_of_driver);
  }
  
  module_init(grlib_apbuart_init);
  module_exit(grlib_apbuart_exit);
  
  MODULE_AUTHOR("Aeroflex Gaisler AB");
  MODULE_DESCRIPTION("GRLIB APBUART serial driver");
  MODULE_VERSION("2.1");
  MODULE_LICENSE("GPL");
  