text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * ipmi_ssif.c
   *
   * The interface to the IPMI driver for SMBus access to a SMBus
   * compliant device.  Called SSIF by the IPMI spec.
   *
   * Author: Intel Corporation
   *         Todd Davis <todd.c.davis@intel.com>
   *
   * Rewritten by Corey Minyard <minyard@acm.org> to support the
   * non-blocking I2C interface, add support for multi-part
   * transactions, add PEC support, and general clenaup.
   *
   * Copyright 2003 Intel Corporation
   * Copyright 2005 MontaVista Software
   */
  
  /*
   * This file holds the "policy" for the interface to the SSIF state
   * machine.  It does the configuration, handles timers and interrupts,
   * and drives the real SSIF state machine.
   */
  
  /*
   * TODO: Figure out how to use SMB alerts.  This will require a new
   * interface into the I2C driver, I believe.
   */
  
  #define pr_fmt(fmt) "ipmi_ssif: " fmt
  
  #if defined(MODVERSIONS)
  #include <linux/modversions.h>
  #endif
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/sched.h>
  #include <linux/seq_file.h>
  #include <linux/timer.h>
  #include <linux/delay.h>
  #include <linux/errno.h>
  #include <linux/spinlock.h>
  #include <linux/slab.h>
  #include <linux/list.h>
  #include <linux/i2c.h>
  #include <linux/ipmi_smi.h>
  #include <linux/init.h>
  #include <linux/dmi.h>
  #include <linux/kthread.h>
  #include <linux/acpi.h>
  #include <linux/ctype.h>
  #include <linux/time64.h>
  #include "ipmi_si_sm.h"
  #include "ipmi_dmi.h"
  
  #define DEVICE_NAME "ipmi_ssif"
  
  #define IPMI_GET_SYSTEM_INTERFACE_CAPABILITIES_CMD	0x57
  
  #define	SSIF_IPMI_REQUEST			2
  #define	SSIF_IPMI_MULTI_PART_REQUEST_START	6
  #define	SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE	7
  #define	SSIF_IPMI_MULTI_PART_REQUEST_END	8
  #define	SSIF_IPMI_RESPONSE			3
  #define	SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE	9
  
  /* ssif_debug is a bit-field
   *	SSIF_DEBUG_MSG -	commands and their responses
   *	SSIF_DEBUG_STATES -	message states
   *	SSIF_DEBUG_TIMING -	 Measure times between events in the driver
   */
  #define SSIF_DEBUG_TIMING	4
  #define SSIF_DEBUG_STATE	2
  #define SSIF_DEBUG_MSG		1
  #define SSIF_NODEBUG		0
  #define SSIF_DEFAULT_DEBUG	(SSIF_NODEBUG)
  
  /*
   * Timer values
   */
  #define SSIF_MSG_USEC		20000	/* 20ms between message tries. */
  #define SSIF_MSG_PART_USEC	5000	/* 5ms for a message part */
  
  /* How many times to we retry sending/receiving the message. */
  #define	SSIF_SEND_RETRIES	5
  #define	SSIF_RECV_RETRIES	250
  
  #define SSIF_MSG_MSEC		(SSIF_MSG_USEC / 1000)
  #define SSIF_MSG_JIFFIES	((SSIF_MSG_USEC * 1000) / TICK_NSEC)
  #define SSIF_MSG_PART_JIFFIES	((SSIF_MSG_PART_USEC * 1000) / TICK_NSEC)
  
  enum ssif_intf_state {
  	SSIF_NORMAL,
  	SSIF_GETTING_FLAGS,
  	SSIF_GETTING_EVENTS,
  	SSIF_CLEARING_FLAGS,
  	SSIF_GETTING_MESSAGES,
  	/* FIXME - add watchdog stuff. */
  };
  
  #define SSIF_IDLE(ssif)	 ((ssif)->ssif_state == SSIF_NORMAL \
  			  && (ssif)->curr_msg == NULL)
  
  /*
   * Indexes into stats[] in ssif_info below.
   */
  enum ssif_stat_indexes {
  	/* Number of total messages sent. */
  	SSIF_STAT_sent_messages = 0,
  
  	/*
  	 * Number of message parts sent.  Messages may be broken into
  	 * parts if they are long.
  	 */
  	SSIF_STAT_sent_messages_parts,
  
  	/*
  	 * Number of time a message was retried.
  	 */
  	SSIF_STAT_send_retries,
  
  	/*
  	 * Number of times the send of a message failed.
  	 */
  	SSIF_STAT_send_errors,
  
  	/*
  	 * Number of message responses received.
  	 */
  	SSIF_STAT_received_messages,
  
  	/*
  	 * Number of message fragments received.
  	 */
  	SSIF_STAT_received_message_parts,
  
  	/*
  	 * Number of times the receive of a message was retried.
  	 */
  	SSIF_STAT_receive_retries,
  
  	/*
  	 * Number of errors receiving messages.
  	 */
  	SSIF_STAT_receive_errors,
  
  	/*
  	 * Number of times a flag fetch was requested.
  	 */
  	SSIF_STAT_flag_fetches,
  
  	/*
  	 * Number of times the hardware didn't follow the state machine.
  	 */
  	SSIF_STAT_hosed,
  
  	/*
  	 * Number of received events.
  	 */
  	SSIF_STAT_events,
  
  	/* Number of asyncronous messages received. */
  	SSIF_STAT_incoming_messages,
  
  	/* Number of watchdog pretimeouts. */
  	SSIF_STAT_watchdog_pretimeouts,
  
  	/* Number of alers received. */
  	SSIF_STAT_alerts,
  
  	/* Always add statistics before this value, it must be last. */
  	SSIF_NUM_STATS
  };
  
  struct ssif_addr_info {
  	struct i2c_board_info binfo;
  	char *adapter_name;
  	int debug;
  	int slave_addr;
  	enum ipmi_addr_src addr_src;
  	union ipmi_smi_info_union addr_info;
  	struct device *dev;
  	struct i2c_client *client;
  
  	struct i2c_client *added_client;
  
  	struct mutex clients_mutex;
  	struct list_head clients;
  
  	struct list_head link;
  };
  
  struct ssif_info;
  
  typedef void (*ssif_i2c_done)(struct ssif_info *ssif_info, int result,
  			     unsigned char *data, unsigned int len);
  
  struct ssif_info {
  	struct ipmi_smi     *intf;
  	spinlock_t	    lock;
  	struct ipmi_smi_msg *waiting_msg;
  	struct ipmi_smi_msg *curr_msg;
  	enum ssif_intf_state ssif_state;
  	unsigned long       ssif_debug;
  
  	struct ipmi_smi_handlers handlers;
  
  	enum ipmi_addr_src addr_source; /* ACPI, PCI, SMBIOS, hardcode, etc. */
  	union ipmi_smi_info_union addr_info;
  
  	/*
  	 * Flags from the last GET_MSG_FLAGS command, used when an ATTN
  	 * is set to hold the flags until we are done handling everything
  	 * from the flags.
  	 */
  #define RECEIVE_MSG_AVAIL	0x01
  #define EVENT_MSG_BUFFER_FULL	0x02
  #define WDT_PRE_TIMEOUT_INT	0x08
  	unsigned char       msg_flags;
  
  	u8		    global_enables;
  	bool		    has_event_buffer;
  	bool		    supports_alert;
  
  	/*
  	 * Used to tell what we should do with alerts.  If we are
  	 * waiting on a response, read the data immediately.
  	 */
  	bool		    got_alert;
  	bool		    waiting_alert;
  
  	/*
  	 * If set to true, this will request events the next time the
  	 * state machine is idle.
  	 */
  	bool                req_events;
  
  	/*
  	 * If set to true, this will request flags the next time the
  	 * state machine is idle.
  	 */
  	bool                req_flags;
  
  	/*
  	 * Used to perform timer operations when run-to-completion
  	 * mode is on.  This is a countdown timer.
  	 */
  	int                 rtc_us_timer;
  
  	/* Used for sending/receiving data.  +1 for the length. */
  	unsigned char data[IPMI_MAX_MSG_LENGTH + 1];
  	unsigned int  data_len;
  
  	/* Temp receive buffer, gets copied into data. */
  	unsigned char recv[I2C_SMBUS_BLOCK_MAX];
  
  	struct i2c_client *client;
  	ssif_i2c_done done_handler;
  
  	/* Thread interface handling */
  	struct task_struct *thread;
  	struct completion wake_thread;
  	bool stopping;
  	int i2c_read_write;
  	int i2c_command;
  	unsigned char *i2c_data;
  	unsigned int i2c_size;
  
  	struct timer_list retry_timer;
  	int retries_left;
  
  	/* Info from SSIF cmd */
  	unsigned char max_xmit_msg_size;
  	unsigned char max_recv_msg_size;
  	bool cmd8_works; /* See test_multipart_messages() for details. */
  	unsigned int  multi_support;
  	int           supports_pec;
  
  #define SSIF_NO_MULTI		0
  #define SSIF_MULTI_2_PART	1
  #define SSIF_MULTI_n_PART	2
  	unsigned char *multi_data;
  	unsigned int  multi_len;
  	unsigned int  multi_pos;
  
  	atomic_t stats[SSIF_NUM_STATS];
  };
  
  #define ssif_inc_stat(ssif, stat) \
  	atomic_inc(&(ssif)->stats[SSIF_STAT_ ## stat])
  #define ssif_get_stat(ssif, stat) \
  	((unsigned int) atomic_read(&(ssif)->stats[SSIF_STAT_ ## stat]))
  
  static bool initialized;
  
  static void return_hosed_msg(struct ssif_info *ssif_info,
  			     struct ipmi_smi_msg *msg);
  static void start_next_msg(struct ssif_info *ssif_info, unsigned long *flags);
  static int start_send(struct ssif_info *ssif_info,
  		      unsigned char   *data,
  		      unsigned int    len);
  
  static unsigned long *ipmi_ssif_lock_cond(struct ssif_info *ssif_info,
  					  unsigned long *flags)
  {
  	spin_lock_irqsave(&ssif_info->lock, *flags);
  	return flags;
  }
  
  static void ipmi_ssif_unlock_cond(struct ssif_info *ssif_info,
  				  unsigned long *flags)
  {
  	spin_unlock_irqrestore(&ssif_info->lock, *flags);
  }
  
  static void deliver_recv_msg(struct ssif_info *ssif_info,
  			     struct ipmi_smi_msg *msg)
  {
  	if (msg->rsp_size < 0) {
  		return_hosed_msg(ssif_info, msg);
  		pr_err("%s: Malformed message: rsp_size = %d\n",
  		       __func__, msg->rsp_size);
  	} else {
  		ipmi_smi_msg_received(ssif_info->intf, msg);
  	}
  }
  
  static void return_hosed_msg(struct ssif_info *ssif_info,
  			     struct ipmi_smi_msg *msg)
  {
  	ssif_inc_stat(ssif_info, hosed);
  
  	/* Make it a response */
  	msg->rsp[0] = msg->data[0] | 4;
  	msg->rsp[1] = msg->data[1];
  	msg->rsp[2] = 0xFF; /* Unknown error. */
  	msg->rsp_size = 3;
  
  	deliver_recv_msg(ssif_info, msg);
  }
  
  /*
   * Must be called with the message lock held.  This will release the
   * message lock.  Note that the caller will check SSIF_IDLE and start a
   * new operation, so there is no need to check for new messages to
   * start in here.
   */
  static void start_clear_flags(struct ssif_info *ssif_info, unsigned long *flags)
  {
  	unsigned char msg[3];
  
  	ssif_info->msg_flags &= ~WDT_PRE_TIMEOUT_INT;
  	ssif_info->ssif_state = SSIF_CLEARING_FLAGS;
  	ipmi_ssif_unlock_cond(ssif_info, flags);
  
  	/* Make sure the watchdog pre-timeout flag is not set at startup. */
  	msg[0] = (IPMI_NETFN_APP_REQUEST << 2);
  	msg[1] = IPMI_CLEAR_MSG_FLAGS_CMD;
  	msg[2] = WDT_PRE_TIMEOUT_INT;
  
  	if (start_send(ssif_info, msg, 3) != 0) {
  		/* Error, just go to normal state. */
  		ssif_info->ssif_state = SSIF_NORMAL;
  	}
  }
  
  static void start_flag_fetch(struct ssif_info *ssif_info, unsigned long *flags)
  {
  	unsigned char mb[2];
  
  	ssif_info->req_flags = false;
  	ssif_info->ssif_state = SSIF_GETTING_FLAGS;
  	ipmi_ssif_unlock_cond(ssif_info, flags);
  
  	mb[0] = (IPMI_NETFN_APP_REQUEST << 2);
  	mb[1] = IPMI_GET_MSG_FLAGS_CMD;
  	if (start_send(ssif_info, mb, 2) != 0)
  		ssif_info->ssif_state = SSIF_NORMAL;
  }
  
  static void check_start_send(struct ssif_info *ssif_info, unsigned long *flags,
  			     struct ipmi_smi_msg *msg)
  {
  	if (start_send(ssif_info, msg->data, msg->data_size) != 0) {
  		unsigned long oflags;
  
  		flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  		ssif_info->curr_msg = NULL;
  		ssif_info->ssif_state = SSIF_NORMAL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		ipmi_free_smi_msg(msg);
  	}
  }
  
  static void start_event_fetch(struct ssif_info *ssif_info, unsigned long *flags)
  {
  	struct ipmi_smi_msg *msg;
  
  	ssif_info->req_events = false;
  
  	msg = ipmi_alloc_smi_msg();
  	if (!msg) {
  		ssif_info->ssif_state = SSIF_NORMAL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		return;
  	}
  
  	ssif_info->curr_msg = msg;
  	ssif_info->ssif_state = SSIF_GETTING_EVENTS;
  	ipmi_ssif_unlock_cond(ssif_info, flags);
  
  	msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
  	msg->data[1] = IPMI_READ_EVENT_MSG_BUFFER_CMD;
  	msg->data_size = 2;
  
  	check_start_send(ssif_info, flags, msg);
  }
  
  static void start_recv_msg_fetch(struct ssif_info *ssif_info,
  				 unsigned long *flags)
  {
  	struct ipmi_smi_msg *msg;
  
  	msg = ipmi_alloc_smi_msg();
  	if (!msg) {
  		ssif_info->ssif_state = SSIF_NORMAL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		return;
  	}
  
  	ssif_info->curr_msg = msg;
  	ssif_info->ssif_state = SSIF_GETTING_MESSAGES;
  	ipmi_ssif_unlock_cond(ssif_info, flags);
  
  	msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
  	msg->data[1] = IPMI_GET_MSG_CMD;
  	msg->data_size = 2;
  
  	check_start_send(ssif_info, flags, msg);
  }
  
  /*
   * Must be called with the message lock held.  This will release the
   * message lock.  Note that the caller will check SSIF_IDLE and start a
   * new operation, so there is no need to check for new messages to
   * start in here.
   */
  static void handle_flags(struct ssif_info *ssif_info, unsigned long *flags)
  {
  	if (ssif_info->msg_flags & WDT_PRE_TIMEOUT_INT) {
  		/* Watchdog pre-timeout */
  		ssif_inc_stat(ssif_info, watchdog_pretimeouts);
  		start_clear_flags(ssif_info, flags);
  		ipmi_smi_watchdog_pretimeout(ssif_info->intf);
  	} else if (ssif_info->msg_flags & RECEIVE_MSG_AVAIL)
  		/* Messages available. */
  		start_recv_msg_fetch(ssif_info, flags);
  	else if (ssif_info->msg_flags & EVENT_MSG_BUFFER_FULL)
  		/* Events available. */
  		start_event_fetch(ssif_info, flags);
  	else {
  		ssif_info->ssif_state = SSIF_NORMAL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  	}
  }
  
  static int ipmi_ssif_thread(void *data)
  {
  	struct ssif_info *ssif_info = data;
  
  	while (!kthread_should_stop()) {
  		int result;
  
  		/* Wait for something to do */
  		result = wait_for_completion_interruptible(
  						&ssif_info->wake_thread);
  		if (ssif_info->stopping)
  			break;
  		if (result == -ERESTARTSYS)
  			continue;
  		init_completion(&ssif_info->wake_thread);
  
  		if (ssif_info->i2c_read_write == I2C_SMBUS_WRITE) {
  			result = i2c_smbus_write_block_data(
  				ssif_info->client, ssif_info->i2c_command,
  				ssif_info->i2c_data[0],
  				ssif_info->i2c_data + 1);
  			ssif_info->done_handler(ssif_info, result, NULL, 0);
  		} else {
  			result = i2c_smbus_read_block_data(
  				ssif_info->client, ssif_info->i2c_command,
  				ssif_info->i2c_data);
  			if (result < 0)
  				ssif_info->done_handler(ssif_info, result,
  							NULL, 0);
  			else
  				ssif_info->done_handler(ssif_info, 0,
  							ssif_info->i2c_data,
  							result);
  		}
  	}
  
  	return 0;
  }
  
  static int ssif_i2c_send(struct ssif_info *ssif_info,
  			ssif_i2c_done handler,
  			int read_write, int command,
  			unsigned char *data, unsigned int size)
  {
  	ssif_info->done_handler = handler;
  
  	ssif_info->i2c_read_write = read_write;
  	ssif_info->i2c_command = command;
  	ssif_info->i2c_data = data;
  	ssif_info->i2c_size = size;
  	complete(&ssif_info->wake_thread);
  	return 0;
  }
  
  
  static void msg_done_handler(struct ssif_info *ssif_info, int result,
  			     unsigned char *data, unsigned int len);
  
  static void start_get(struct ssif_info *ssif_info)
  {
  	int rv;
  
  	ssif_info->rtc_us_timer = 0;
  	ssif_info->multi_pos = 0;
  
  	rv = ssif_i2c_send(ssif_info, msg_done_handler, I2C_SMBUS_READ,
  			  SSIF_IPMI_RESPONSE,
  			  ssif_info->recv, I2C_SMBUS_BLOCK_DATA);
  	if (rv < 0) {
  		/* request failed, just return the error. */
  		if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  			pr_info("Error from i2c_non_blocking_op(5)\n");
  
  		msg_done_handler(ssif_info, -EIO, NULL, 0);
  	}
  }
  
  static void retry_timeout(struct timer_list *t)
  {
  	struct ssif_info *ssif_info = from_timer(ssif_info, t, retry_timer);
  	unsigned long oflags, *flags;
  	bool waiting;
  
  	if (ssif_info->stopping)
  		return;
  
  	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  	waiting = ssif_info->waiting_alert;
  	ssif_info->waiting_alert = false;
  	ipmi_ssif_unlock_cond(ssif_info, flags);
  
  	if (waiting)
  		start_get(ssif_info);
  }
  
  
  static void ssif_alert(struct i2c_client *client, enum i2c_alert_protocol type,
  		       unsigned int data)
  {
  	struct ssif_info *ssif_info = i2c_get_clientdata(client);
  	unsigned long oflags, *flags;
  	bool do_get = false;
  
  	if (type != I2C_PROTOCOL_SMBUS_ALERT)
  		return;
  
  	ssif_inc_stat(ssif_info, alerts);
  
  	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  	if (ssif_info->waiting_alert) {
  		ssif_info->waiting_alert = false;
  		del_timer(&ssif_info->retry_timer);
  		do_get = true;
  	} else if (ssif_info->curr_msg) {
  		ssif_info->got_alert = true;
  	}
  	ipmi_ssif_unlock_cond(ssif_info, flags);
  	if (do_get)
  		start_get(ssif_info);
  }
  
  static int start_resend(struct ssif_info *ssif_info);
  
  static void msg_done_handler(struct ssif_info *ssif_info, int result,
  			     unsigned char *data, unsigned int len)
  {
  	struct ipmi_smi_msg *msg;
  	unsigned long oflags, *flags;
  	int rv;
  
  	/*
  	 * We are single-threaded here, so no need for a lock until we
  	 * start messing with driver states or the queues.
  	 */
  
  	if (result < 0) {
  		ssif_info->retries_left--;
  		if (ssif_info->retries_left > 0) {
  			ssif_inc_stat(ssif_info, receive_retries);
  
  			flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  			ssif_info->waiting_alert = true;
  			ssif_info->rtc_us_timer = SSIF_MSG_USEC;
  			if (!ssif_info->stopping)
  				mod_timer(&ssif_info->retry_timer,
  					  jiffies + SSIF_MSG_JIFFIES);
  			ipmi_ssif_unlock_cond(ssif_info, flags);
  			return;
  		}
  
  		ssif_inc_stat(ssif_info, receive_errors);
  
  		if  (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  			pr_info("Error in msg_done_handler: %d\n", result);
  		len = 0;
  		goto continue_op;
  	}
  
  	if ((len > 1) && (ssif_info->multi_pos == 0)
  				&& (data[0] == 0x00) && (data[1] == 0x01)) {
  		/* Start of multi-part read.  Start the next transaction. */
  		int i;
  
  		ssif_inc_stat(ssif_info, received_message_parts);
  
  		/* Remove the multi-part read marker. */
  		len -= 2;
  		data += 2;
  		for (i = 0; i < len; i++)
  			ssif_info->data[i] = data[i];
  		ssif_info->multi_len = len;
  		ssif_info->multi_pos = 1;
  
  		rv = ssif_i2c_send(ssif_info, msg_done_handler, I2C_SMBUS_READ,
  				  SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE,
  				  ssif_info->recv, I2C_SMBUS_BLOCK_DATA);
  		if (rv < 0) {
  			if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  				pr_info("Error from i2c_non_blocking_op(1)\n");
  
  			result = -EIO;
  		} else
  			return;
  	} else if (ssif_info->multi_pos) {
  		/* Middle of multi-part read.  Start the next transaction. */
  		int i;
  		unsigned char blocknum;
  
  		if (len == 0) {
  			result = -EIO;
  			if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  				pr_info("Middle message with no data\n");
  
  			goto continue_op;
  		}
  
  		blocknum = data[0];
  		len--;
  		data++;
  
  		if (blocknum != 0xff && len != 31) {
  		    /* All blocks but the last must have 31 data bytes. */
  			result = -EIO;
  			if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  				pr_info("Received middle message <31\n");
  
  			goto continue_op;
  		}
  
  		if (ssif_info->multi_len + len > IPMI_MAX_MSG_LENGTH) {
  			/* Received message too big, abort the operation. */
  			result = -E2BIG;
  			if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  				pr_info("Received message too big\n");
  
  			goto continue_op;
  		}
  
  		for (i = 0; i < len; i++)
  			ssif_info->data[i + ssif_info->multi_len] = data[i];
  		ssif_info->multi_len += len;
  		if (blocknum == 0xff) {
  			/* End of read */
  			len = ssif_info->multi_len;
  			data = ssif_info->data;
  		} else if (blocknum != ssif_info->multi_pos) {
  			/*
  			 * Out of sequence block, just abort.  Block
  			 * numbers start at zero for the second block,
  			 * but multi_pos starts at one, so the +1.
  			 */
  			result = -EIO;
  		} else {
  			ssif_inc_stat(ssif_info, received_message_parts);
  
  			ssif_info->multi_pos++;
  
  			rv = ssif_i2c_send(ssif_info, msg_done_handler,
  					   I2C_SMBUS_READ,
  					   SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE,
  					   ssif_info->recv,
  					   I2C_SMBUS_BLOCK_DATA);
  			if (rv < 0) {
  				if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  					pr_info("Error from ssif_i2c_send\n");
  
  				result = -EIO;
  			} else
  				return;
  		}
  	}
  
   continue_op:
  	if (result < 0) {
  		ssif_inc_stat(ssif_info, receive_errors);
  	} else {
  		ssif_inc_stat(ssif_info, received_messages);
  		ssif_inc_stat(ssif_info, received_message_parts);
  	}
  
  	if (ssif_info->ssif_debug & SSIF_DEBUG_STATE)
  		pr_info("DONE 1: state = %d, result=%d\n",
  			ssif_info->ssif_state, result);
  
  	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  	msg = ssif_info->curr_msg;
  	if (msg) {
  		msg->rsp_size = len;
  		if (msg->rsp_size > IPMI_MAX_MSG_LENGTH)
  			msg->rsp_size = IPMI_MAX_MSG_LENGTH;
  		memcpy(msg->rsp, data, msg->rsp_size);
  		ssif_info->curr_msg = NULL;
  	}
  
  	switch (ssif_info->ssif_state) {
  	case SSIF_NORMAL:
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		if (!msg)
  			break;
  
  		if (result < 0)
  			return_hosed_msg(ssif_info, msg);
  		else
  			deliver_recv_msg(ssif_info, msg);
  		break;
  
  	case SSIF_GETTING_FLAGS:
  		/* We got the flags from the SSIF, now handle them. */
  		if ((result < 0) || (len < 4) || (data[2] != 0)) {
  			/*
  			 * Error fetching flags, or invalid length,
  			 * just give up for now.
  			 */
  			ssif_info->ssif_state = SSIF_NORMAL;
  			ipmi_ssif_unlock_cond(ssif_info, flags);
  			pr_warn("Error getting flags: %d %d, %x\n",
  				result, len, (len >= 3) ? data[2] : 0);
  		} else if (data[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
  			   || data[1] != IPMI_GET_MSG_FLAGS_CMD) {
  			/*
  			 * Don't abort here, maybe it was a queued
  			 * response to a previous command.
  			 */
  			ipmi_ssif_unlock_cond(ssif_info, flags);
  			pr_warn("Invalid response getting flags: %x %x\n",
  				data[0], data[1]);
  		} else {
  			ssif_inc_stat(ssif_info, flag_fetches);
  			ssif_info->msg_flags = data[3];
  			handle_flags(ssif_info, flags);
  		}
  		break;
  
  	case SSIF_CLEARING_FLAGS:
  		/* We cleared the flags. */
  		if ((result < 0) || (len < 3) || (data[2] != 0)) {
  			/* Error clearing flags */
  			pr_warn("Error clearing flags: %d %d, %x\n",
  				result, len, (len >= 3) ? data[2] : 0);
  		} else if (data[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
  			   || data[1] != IPMI_CLEAR_MSG_FLAGS_CMD) {
  			pr_warn("Invalid response clearing flags: %x %x\n",
  				data[0], data[1]);
  		}
  		ssif_info->ssif_state = SSIF_NORMAL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		break;
  
  	case SSIF_GETTING_EVENTS:
  		if ((result < 0) || (len < 3) || (msg->rsp[2] != 0)) {
  			/* Error getting event, probably done. */
  			msg->done(msg);
  
  			/* Take off the event flag. */
  			ssif_info->msg_flags &= ~EVENT_MSG_BUFFER_FULL;
  			handle_flags(ssif_info, flags);
  		} else if (msg->rsp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
  			   || msg->rsp[1] != IPMI_READ_EVENT_MSG_BUFFER_CMD) {
  			pr_warn("Invalid response getting events: %x %x\n",
  				msg->rsp[0], msg->rsp[1]);
  			msg->done(msg);
  			/* Take off the event flag. */
  			ssif_info->msg_flags &= ~EVENT_MSG_BUFFER_FULL;
  			handle_flags(ssif_info, flags);
  		} else {
  			handle_flags(ssif_info, flags);
  			ssif_inc_stat(ssif_info, events);
  			deliver_recv_msg(ssif_info, msg);
  		}
  		break;
  
  	case SSIF_GETTING_MESSAGES:
  		if ((result < 0) || (len < 3) || (msg->rsp[2] != 0)) {
  			/* Error getting event, probably done. */
  			msg->done(msg);
  
  			/* Take off the msg flag. */
  			ssif_info->msg_flags &= ~RECEIVE_MSG_AVAIL;
  			handle_flags(ssif_info, flags);
  		} else if (msg->rsp[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
  			   || msg->rsp[1] != IPMI_GET_MSG_CMD) {
  			pr_warn("Invalid response clearing flags: %x %x\n",
  				msg->rsp[0], msg->rsp[1]);
  			msg->done(msg);
  
  			/* Take off the msg flag. */
  			ssif_info->msg_flags &= ~RECEIVE_MSG_AVAIL;
  			handle_flags(ssif_info, flags);
  		} else {
  			ssif_inc_stat(ssif_info, incoming_messages);
  			handle_flags(ssif_info, flags);
  			deliver_recv_msg(ssif_info, msg);
  		}
  		break;
  	}
  
  	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  	if (SSIF_IDLE(ssif_info) && !ssif_info->stopping) {
  		if (ssif_info->req_events)
  			start_event_fetch(ssif_info, flags);
  		else if (ssif_info->req_flags)
  			start_flag_fetch(ssif_info, flags);
  		else
  			start_next_msg(ssif_info, flags);
  	} else
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  
  	if (ssif_info->ssif_debug & SSIF_DEBUG_STATE)
  		pr_info("DONE 2: state = %d.\n", ssif_info->ssif_state);
  }
  
  static void msg_written_handler(struct ssif_info *ssif_info, int result,
  				unsigned char *data, unsigned int len)
  {
  	int rv;
  
  	/* We are single-threaded here, so no need for a lock. */
  	if (result < 0) {
  		ssif_info->retries_left--;
  		if (ssif_info->retries_left > 0) {
  			if (!start_resend(ssif_info)) {
  				ssif_inc_stat(ssif_info, send_retries);
  				return;
  			}
  			/* request failed, just return the error. */
  			ssif_inc_stat(ssif_info, send_errors);
  
  			if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  				pr_info("%s: Out of retries\n", __func__);
  			msg_done_handler(ssif_info, -EIO, NULL, 0);
  			return;
  		}
  
  		ssif_inc_stat(ssif_info, send_errors);
  
  		/*
  		 * Got an error on transmit, let the done routine
  		 * handle it.
  		 */
  		if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  			pr_info("Error in msg_written_handler: %d\n", result);
  
  		msg_done_handler(ssif_info, result, NULL, 0);
  		return;
  	}
  
  	if (ssif_info->multi_data) {
  		/*
  		 * In the middle of a multi-data write.  See the comment
  		 * in the SSIF_MULTI_n_PART case in the probe function
  		 * for details on the intricacies of this.
  		 */
  		int left, to_write;
  		unsigned char *data_to_send;
  		unsigned char cmd;
  
  		ssif_inc_stat(ssif_info, sent_messages_parts);
  
  		left = ssif_info->multi_len - ssif_info->multi_pos;
  		to_write = left;
  		if (to_write > 32)
  			to_write = 32;
  		/* Length byte. */
  		ssif_info->multi_data[ssif_info->multi_pos] = to_write;
  		data_to_send = ssif_info->multi_data + ssif_info->multi_pos;
  		ssif_info->multi_pos += to_write;
  		cmd = SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE;
  		if (ssif_info->cmd8_works) {
  			if (left == to_write) {
  				cmd = SSIF_IPMI_MULTI_PART_REQUEST_END;
  				ssif_info->multi_data = NULL;
  			}
  		} else if (to_write < 32) {
  			ssif_info->multi_data = NULL;
  		}
  
  		rv = ssif_i2c_send(ssif_info, msg_written_handler,
  				   I2C_SMBUS_WRITE, cmd,
  				   data_to_send, I2C_SMBUS_BLOCK_DATA);
  		if (rv < 0) {
  			/* request failed, just return the error. */
  			ssif_inc_stat(ssif_info, send_errors);
  
  			if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
  				pr_info("Error from i2c_non_blocking_op(3)\n");
  			msg_done_handler(ssif_info, -EIO, NULL, 0);
  		}
  	} else {
  		/* Ready to request the result. */
  		unsigned long oflags, *flags;
  
  		ssif_inc_stat(ssif_info, sent_messages);
  		ssif_inc_stat(ssif_info, sent_messages_parts);
  
  		flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  		if (ssif_info->got_alert) {
  			/* The result is already ready, just start it. */
  			ssif_info->got_alert = false;
  			ipmi_ssif_unlock_cond(ssif_info, flags);
  			start_get(ssif_info);
  		} else {
  			/* Wait a jiffie then request the next message */
  			ssif_info->waiting_alert = true;
  			ssif_info->retries_left = SSIF_RECV_RETRIES;
  			ssif_info->rtc_us_timer = SSIF_MSG_PART_USEC;
  			if (!ssif_info->stopping)
  				mod_timer(&ssif_info->retry_timer,
  					  jiffies + SSIF_MSG_PART_JIFFIES);
  			ipmi_ssif_unlock_cond(ssif_info, flags);
  		}
  	}
  }
  
  static int start_resend(struct ssif_info *ssif_info)
  {
  	int rv;
  	int command;
  
  	ssif_info->got_alert = false;
  
  	if (ssif_info->data_len > 32) {
  		command = SSIF_IPMI_MULTI_PART_REQUEST_START;
  		ssif_info->multi_data = ssif_info->data;
  		ssif_info->multi_len = ssif_info->data_len;
  		/*
  		 * Subtle thing, this is 32, not 33, because we will
  		 * overwrite the thing at position 32 (which was just
  		 * transmitted) with the new length.
  		 */
  		ssif_info->multi_pos = 32;
  		ssif_info->data[0] = 32;
  	} else {
  		ssif_info->multi_data = NULL;
  		command = SSIF_IPMI_REQUEST;
  		ssif_info->data[0] = ssif_info->data_len;
  	}
  
  	rv = ssif_i2c_send(ssif_info, msg_written_handler, I2C_SMBUS_WRITE,
  			  command, ssif_info->data, I2C_SMBUS_BLOCK_DATA);
  	if (rv && (ssif_info->ssif_debug & SSIF_DEBUG_MSG))
  		pr_info("Error from i2c_non_blocking_op(4)\n");
  	return rv;
  }
  
  static int start_send(struct ssif_info *ssif_info,
  		      unsigned char   *data,
  		      unsigned int    len)
  {
  	if (len > IPMI_MAX_MSG_LENGTH)
  		return -E2BIG;
  	if (len > ssif_info->max_xmit_msg_size)
  		return -E2BIG;
  
  	ssif_info->retries_left = SSIF_SEND_RETRIES;
  	memcpy(ssif_info->data + 1, data, len);
  	ssif_info->data_len = len;
  	return start_resend(ssif_info);
  }
  
  /* Must be called with the message lock held. */
  static void start_next_msg(struct ssif_info *ssif_info, unsigned long *flags)
  {
  	struct ipmi_smi_msg *msg;
  	unsigned long oflags;
  
   restart:
  	if (!SSIF_IDLE(ssif_info)) {
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		return;
  	}
  
  	if (!ssif_info->waiting_msg) {
  		ssif_info->curr_msg = NULL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  	} else {
  		int rv;
  
  		ssif_info->curr_msg = ssif_info->waiting_msg;
  		ssif_info->waiting_msg = NULL;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  		rv = start_send(ssif_info,
  				ssif_info->curr_msg->data,
  				ssif_info->curr_msg->data_size);
  		if (rv) {
  			msg = ssif_info->curr_msg;
  			ssif_info->curr_msg = NULL;
  			return_hosed_msg(ssif_info, msg);
  			flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  			goto restart;
  		}
  	}
  }
  
  static void sender(void                *send_info,
  		   struct ipmi_smi_msg *msg)
  {
  	struct ssif_info *ssif_info = (struct ssif_info *) send_info;
  	unsigned long oflags, *flags;
  
  	BUG_ON(ssif_info->waiting_msg);
  	ssif_info->waiting_msg = msg;
  
  	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  	start_next_msg(ssif_info, flags);
  
  	if (ssif_info->ssif_debug & SSIF_DEBUG_TIMING) {
  		struct timespec64 t;
  
  		ktime_get_real_ts64(&t);
  		pr_info("**Enqueue %02x %02x: %lld.%6.6ld\n",
  			msg->data[0], msg->data[1],
  			(long long)t.tv_sec, (long)t.tv_nsec / NSEC_PER_USEC);
  	}
  }
  
  static int get_smi_info(void *send_info, struct ipmi_smi_info *data)
  {
  	struct ssif_info *ssif_info = send_info;
  
  	data->addr_src = ssif_info->addr_source;
  	data->dev = &ssif_info->client->dev;
  	data->addr_info = ssif_info->addr_info;
  	get_device(data->dev);
  
  	return 0;
  }
  
  /*
   * Instead of having our own timer to periodically check the message
   * flags, we let the message handler drive us.
   */
  static void request_events(void *send_info)
  {
  	struct ssif_info *ssif_info = (struct ssif_info *) send_info;
  	unsigned long oflags, *flags;
  
  	if (!ssif_info->has_event_buffer)
  		return;
  
  	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
  	/*
  	 * Request flags first, not events, because the lower layer
  	 * doesn't have a way to send an attention.  But make sure
  	 * event checking still happens.
  	 */
  	ssif_info->req_events = true;
  	if (SSIF_IDLE(ssif_info))
  		start_flag_fetch(ssif_info, flags);
  	else {
  		ssif_info->req_flags = true;
  		ipmi_ssif_unlock_cond(ssif_info, flags);
  	}
  }
  
  static int ssif_start_processing(void            *send_info,
  				 struct ipmi_smi *intf)
  {
  	struct ssif_info *ssif_info = send_info;
  
  	ssif_info->intf = intf;
  
  	return 0;
  }
  
  #define MAX_SSIF_BMCS 4
  
  static unsigned short addr[MAX_SSIF_BMCS];
  static int num_addrs;
  module_param_array(addr, ushort, &num_addrs, 0);
  MODULE_PARM_DESC(addr, "The addresses to scan for IPMI BMCs on the SSIFs.");
  
  static char *adapter_name[MAX_SSIF_BMCS];
  static int num_adapter_names;
  module_param_array(adapter_name, charp, &num_adapter_names, 0);
  MODULE_PARM_DESC(adapter_name, "The string name of the I2C device that has the BMC.  By default all devices are scanned.");
  
  static int slave_addrs[MAX_SSIF_BMCS];
  static int num_slave_addrs;
  module_param_array(slave_addrs, int, &num_slave_addrs, 0);
  MODULE_PARM_DESC(slave_addrs,
  		 "The default IPMB slave address for the controller.");
  
  static bool alerts_broken;
  module_param(alerts_broken, bool, 0);
  MODULE_PARM_DESC(alerts_broken, "Don't enable alerts for the controller.");
  
  /*
   * Bit 0 enables message debugging, bit 1 enables state debugging, and
   * bit 2 enables timing debugging.  This is an array indexed by
   * interface number"
   */
  static int dbg[MAX_SSIF_BMCS];
  static int num_dbg;
  module_param_array(dbg, int, &num_dbg, 0);
  MODULE_PARM_DESC(dbg, "Turn on debugging.");
  
  static bool ssif_dbg_probe;
  module_param_named(dbg_probe, ssif_dbg_probe, bool, 0);
  MODULE_PARM_DESC(dbg_probe, "Enable debugging of probing of adapters.");
  
  static bool ssif_tryacpi = true;
  module_param_named(tryacpi, ssif_tryacpi, bool, 0);
  MODULE_PARM_DESC(tryacpi, "Setting this to zero will disable the default scan of the interfaces identified via ACPI");
  
  static bool ssif_trydmi = true;
  module_param_named(trydmi, ssif_trydmi, bool, 0);
  MODULE_PARM_DESC(trydmi, "Setting this to zero will disable the default scan of the interfaces identified via DMI (SMBIOS)");
  
  static DEFINE_MUTEX(ssif_infos_mutex);
  static LIST_HEAD(ssif_infos);
  
  #define IPMI_SSIF_ATTR(name) \
  static ssize_t ipmi_##name##_show(struct device *dev,			\
  				  struct device_attribute *attr,	\
  				  char *buf)				\
  {									\
  	struct ssif_info *ssif_info = dev_get_drvdata(dev);		\
  									\
  	return snprintf(buf, 10, "%u\n", ssif_get_stat(ssif_info, name));\
  }									\
  static DEVICE_ATTR(name, S_IRUGO, ipmi_##name##_show, NULL)
  
  static ssize_t ipmi_type_show(struct device *dev,
  			      struct device_attribute *attr,
  			      char *buf)
  {
  	return snprintf(buf, 10, "ssif\n");
  }
  static DEVICE_ATTR(type, S_IRUGO, ipmi_type_show, NULL);
  
  IPMI_SSIF_ATTR(sent_messages);
  IPMI_SSIF_ATTR(sent_messages_parts);
  IPMI_SSIF_ATTR(send_retries);
  IPMI_SSIF_ATTR(send_errors);
  IPMI_SSIF_ATTR(received_messages);
  IPMI_SSIF_ATTR(received_message_parts);
  IPMI_SSIF_ATTR(receive_retries);
  IPMI_SSIF_ATTR(receive_errors);
  IPMI_SSIF_ATTR(flag_fetches);
  IPMI_SSIF_ATTR(hosed);
  IPMI_SSIF_ATTR(events);
  IPMI_SSIF_ATTR(watchdog_pretimeouts);
  IPMI_SSIF_ATTR(alerts);
  
  static struct attribute *ipmi_ssif_dev_attrs[] = {
  	&dev_attr_type.attr,
  	&dev_attr_sent_messages.attr,
  	&dev_attr_sent_messages_parts.attr,
  	&dev_attr_send_retries.attr,
  	&dev_attr_send_errors.attr,
  	&dev_attr_received_messages.attr,
  	&dev_attr_received_message_parts.attr,
  	&dev_attr_receive_retries.attr,
  	&dev_attr_receive_errors.attr,
  	&dev_attr_flag_fetches.attr,
  	&dev_attr_hosed.attr,
  	&dev_attr_events.attr,
  	&dev_attr_watchdog_pretimeouts.attr,
  	&dev_attr_alerts.attr,
  	NULL
  };
  
  static const struct attribute_group ipmi_ssif_dev_attr_group = {
  	.attrs		= ipmi_ssif_dev_attrs,
  };
  
  static void shutdown_ssif(void *send_info)
  {
  	struct ssif_info *ssif_info = send_info;
  
  	device_remove_group(&ssif_info->client->dev, &ipmi_ssif_dev_attr_group);
  	dev_set_drvdata(&ssif_info->client->dev, NULL);
  
  	/* make sure the driver is not looking for flags any more. */
  	while (ssif_info->ssif_state != SSIF_NORMAL)
  		schedule_timeout(1);
  
  	ssif_info->stopping = true;
  	del_timer_sync(&ssif_info->retry_timer);
  	if (ssif_info->thread) {
  		complete(&ssif_info->wake_thread);
  		kthread_stop(ssif_info->thread);
  	}
  }
  
  static int ssif_remove(struct i2c_client *client)
  {
  	struct ssif_info *ssif_info = i2c_get_clientdata(client);
  	struct ssif_addr_info *addr_info;
  
  	if (!ssif_info)
  		return 0;
  
  	/*
  	 * After this point, we won't deliver anything asychronously
  	 * to the message handler.  We can unregister ourself.
  	 */
  	ipmi_unregister_smi(ssif_info->intf);
  
  	list_for_each_entry(addr_info, &ssif_infos, link) {
  		if (addr_info->client == client) {
  			addr_info->client = NULL;
  			break;
  		}
  	}
  
  	kfree(ssif_info);
  
  	return 0;
  }
  
  static int read_response(struct i2c_client *client, unsigned char *resp)
  {
  	int ret = -ENODEV, retry_cnt = SSIF_RECV_RETRIES;
  
  	while (retry_cnt > 0) {
  		ret = i2c_smbus_read_block_data(client, SSIF_IPMI_RESPONSE,
  						resp);
  		if (ret > 0)
  			break;
  		msleep(SSIF_MSG_MSEC);
  		retry_cnt--;
  		if (retry_cnt <= 0)
  			break;
  	}
  
  	return ret;
  }
  
  static int do_cmd(struct i2c_client *client, int len, unsigned char *msg,
  		  int *resp_len, unsigned char *resp)
  {
  	int retry_cnt;
  	int ret;
  
  	retry_cnt = SSIF_SEND_RETRIES;
   retry1:
  	ret = i2c_smbus_write_block_data(client, SSIF_IPMI_REQUEST, len, msg);
  	if (ret) {
  		retry_cnt--;
  		if (retry_cnt > 0)
  			goto retry1;
  		return -ENODEV;
  	}
  
  	ret = read_response(client, resp);
  	if (ret > 0) {
  		/* Validate that the response is correct. */
  		if (ret < 3 ||
  		    (resp[0] != (msg[0] | (1 << 2))) ||
  		    (resp[1] != msg[1]))
  			ret = -EINVAL;
  		else if (ret > IPMI_MAX_MSG_LENGTH) {
  			ret = -E2BIG;
  		} else {
  			*resp_len = ret;
  			ret = 0;
  		}
  	}
  
  	return ret;
  }
  
  static int ssif_detect(struct i2c_client *client, struct i2c_board_info *info)
  {
  	unsigned char *resp;
  	unsigned char msg[3];
  	int           rv;
  	int           len;
  
  	resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
  	if (!resp)
  		return -ENOMEM;
  
  	/* Do a Get Device ID command, since it is required. */
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_GET_DEVICE_ID_CMD;
  	rv = do_cmd(client, 2, msg, &len, resp);
  	if (rv)
  		rv = -ENODEV;
  	else
  		strlcpy(info->type, DEVICE_NAME, I2C_NAME_SIZE);
  	kfree(resp);
  	return rv;
  }
  
  static int strcmp_nospace(char *s1, char *s2)
  {
  	while (*s1 && *s2) {
  		while (isspace(*s1))
  			s1++;
  		while (isspace(*s2))
  			s2++;
  		if (*s1 > *s2)
  			return 1;
  		if (*s1 < *s2)
  			return -1;
  		s1++;
  		s2++;
  	}
  	return 0;
  }
  
  static struct ssif_addr_info *ssif_info_find(unsigned short addr,
  					     char *adapter_name,
  					     bool match_null_name)
  {
  	struct ssif_addr_info *info, *found = NULL;
  
  restart:
  	list_for_each_entry(info, &ssif_infos, link) {
  		if (info->binfo.addr == addr) {
  			if (info->adapter_name || adapter_name) {
  				if (!info->adapter_name != !adapter_name) {
  					/* One is NULL and one is not */
  					continue;
  				}
  				if (adapter_name &&
  				    strcmp_nospace(info->adapter_name,
  						   adapter_name))
  					/* Names do not match */
  					continue;
  			}
  			found = info;
  			break;
  		}
  	}
  
  	if (!found && match_null_name) {
  		/* Try to get an exact match first, then try with a NULL name */
  		adapter_name = NULL;
  		match_null_name = false;
  		goto restart;
  	}
  
  	return found;
  }
  
  static bool check_acpi(struct ssif_info *ssif_info, struct device *dev)
  {
  #ifdef CONFIG_ACPI
  	acpi_handle acpi_handle;
  
  	acpi_handle = ACPI_HANDLE(dev);
  	if (acpi_handle) {
  		ssif_info->addr_source = SI_ACPI;
  		ssif_info->addr_info.acpi_info.acpi_handle = acpi_handle;
  		return true;
  	}
  #endif
  	return false;
  }
  
  static int find_slave_address(struct i2c_client *client, int slave_addr)
  {
  #ifdef CONFIG_IPMI_DMI_DECODE
  	if (!slave_addr)
  		slave_addr = ipmi_dmi_get_slave_addr(
  			SI_TYPE_INVALID,
  			i2c_adapter_id(client->adapter),
  			client->addr);
  #endif
  
  	return slave_addr;
  }
  
  static int start_multipart_test(struct i2c_client *client,
  				unsigned char *msg, bool do_middle)
  {
  	int retry_cnt = SSIF_SEND_RETRIES, ret;
  
  retry_write:
  	ret = i2c_smbus_write_block_data(client,
  					 SSIF_IPMI_MULTI_PART_REQUEST_START,
  					 32, msg);
  	if (ret) {
  		retry_cnt--;
  		if (retry_cnt > 0)
  			goto retry_write;
  		dev_err(&client->dev, "Could not write multi-part start, though the BMC said it could handle it.  Just limit sends to one part.\n");
  		return ret;
  	}
  
  	if (!do_middle)
  		return 0;
  
  	ret = i2c_smbus_write_block_data(client,
  					 SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
  					 32, msg + 32);
  	if (ret) {
  		dev_err(&client->dev, "Could not write multi-part middle, though the BMC said it could handle it.  Just limit sends to one part.\n");
  		return ret;
  	}
  
  	return 0;
  }
  
  static void test_multipart_messages(struct i2c_client *client,
  				    struct ssif_info *ssif_info,
  				    unsigned char *resp)
  {
  	unsigned char msg[65];
  	int ret;
  	bool do_middle;
  
  	if (ssif_info->max_xmit_msg_size <= 32)
  		return;
  
  	do_middle = ssif_info->max_xmit_msg_size > 63;
  
  	memset(msg, 0, sizeof(msg));
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_GET_DEVICE_ID_CMD;
  
  	/*
  	 * The specification is all messed up dealing with sending
  	 * multi-part messages.  Per what the specification says, it
  	 * is impossible to send a message that is a multiple of 32
  	 * bytes, except for 32 itself.  It talks about a "start"
  	 * transaction (cmd=6) that must be 32 bytes, "middle"
  	 * transaction (cmd=7) that must be 32 bytes, and an "end"
  	 * transaction.  The "end" transaction is shown as cmd=7 in
  	 * the text, but if that's the case there is no way to
  	 * differentiate between a middle and end part except the
  	 * length being less than 32.  But there is a table at the far
  	 * end of the section (that I had never noticed until someone
  	 * pointed it out to me) that mentions it as cmd=8.
  	 *
  	 * After some thought, I think the example is wrong and the
  	 * end transaction should be cmd=8.  But some systems don't
  	 * implement cmd=8, they use a zero-length end transaction,
  	 * even though that violates the SMBus specification.
  	 *
  	 * So, to work around this, this code tests if cmd=8 works.
  	 * If it does, then we use that.  If not, it tests zero-
  	 * byte end transactions.  If that works, good.  If not,
  	 * we only allow 63-byte transactions max.
  	 */
  
  	ret = start_multipart_test(client, msg, do_middle);
  	if (ret)
  		goto out_no_multi_part;
  
  	ret = i2c_smbus_write_block_data(client,
  					 SSIF_IPMI_MULTI_PART_REQUEST_END,
  					 1, msg + 64);
  
  	if (!ret)
  		ret = read_response(client, resp);
  
  	if (ret > 0) {
  		/* End transactions work, we are good. */
  		ssif_info->cmd8_works = true;
  		return;
  	}
  
  	ret = start_multipart_test(client, msg, do_middle);
  	if (ret) {
  		dev_err(&client->dev, "Second multipart test failed.\n");
  		goto out_no_multi_part;
  	}
  
  	ret = i2c_smbus_write_block_data(client,
  					 SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
  					 0, msg + 64);
  	if (!ret)
  		ret = read_response(client, resp);
  	if (ret > 0)
  		/* Zero-size end parts work, use those. */
  		return;
  
  	/* Limit to 63 bytes and use a short middle command to mark the end. */
  	if (ssif_info->max_xmit_msg_size > 63)
  		ssif_info->max_xmit_msg_size = 63;
  	return;
  
  out_no_multi_part:
  	ssif_info->max_xmit_msg_size = 32;
  	return;
  }
  
  /*
   * Global enables we care about.
   */
  #define GLOBAL_ENABLES_MASK (IPMI_BMC_EVT_MSG_BUFF | IPMI_BMC_RCV_MSG_INTR | \
  			     IPMI_BMC_EVT_MSG_INTR)
  
  static int ssif_probe(struct i2c_client *client, const struct i2c_device_id *id)
  {
  	unsigned char     msg[3];
  	unsigned char     *resp;
  	struct ssif_info   *ssif_info;
  	int               rv = 0;
  	int               len;
  	int               i;
  	u8		  slave_addr = 0;
  	struct ssif_addr_info *addr_info = NULL;
  
  	resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
  	if (!resp)
  		return -ENOMEM;
  
  	ssif_info = kzalloc(sizeof(*ssif_info), GFP_KERNEL);
  	if (!ssif_info) {
  		kfree(resp);
  		return -ENOMEM;
  	}
  
  	if (!check_acpi(ssif_info, &client->dev)) {
  		addr_info = ssif_info_find(client->addr, client->adapter->name,
  					   true);
  		if (!addr_info) {
  			/* Must have come in through sysfs. */
  			ssif_info->addr_source = SI_HOTMOD;
  		} else {
  			ssif_info->addr_source = addr_info->addr_src;
  			ssif_info->ssif_debug = addr_info->debug;
  			ssif_info->addr_info = addr_info->addr_info;
  			addr_info->client = client;
  			slave_addr = addr_info->slave_addr;
  		}
  	}
  
  	slave_addr = find_slave_address(client, slave_addr);
  
  	pr_info("Trying %s-specified SSIF interface at i2c address 0x%x, adapter %s, slave address 0x%x\n",
  		ipmi_addr_src_to_str(ssif_info->addr_source),
  		client->addr, client->adapter->name, slave_addr);
  
  	ssif_info->client = client;
  	i2c_set_clientdata(client, ssif_info);
  
  	/* Now check for system interface capabilities */
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_GET_SYSTEM_INTERFACE_CAPABILITIES_CMD;
  	msg[2] = 0; /* SSIF */
  	rv = do_cmd(client, 3, msg, &len, resp);
  	if (!rv && (len >= 3) && (resp[2] == 0)) {
  		if (len < 7) {
  			if (ssif_dbg_probe)
  				pr_info("SSIF info too short: %d\n", len);
  			goto no_support;
  		}
  
  		/* Got a good SSIF response, handle it. */
  		ssif_info->max_xmit_msg_size = resp[5];
  		ssif_info->max_recv_msg_size = resp[6];
  		ssif_info->multi_support = (resp[4] >> 6) & 0x3;
  		ssif_info->supports_pec = (resp[4] >> 3) & 0x1;
  
  		/* Sanitize the data */
  		switch (ssif_info->multi_support) {
  		case SSIF_NO_MULTI:
  			if (ssif_info->max_xmit_msg_size > 32)
  				ssif_info->max_xmit_msg_size = 32;
  			if (ssif_info->max_recv_msg_size > 32)
  				ssif_info->max_recv_msg_size = 32;
  			break;
  
  		case SSIF_MULTI_2_PART:
  			if (ssif_info->max_xmit_msg_size > 63)
  				ssif_info->max_xmit_msg_size = 63;
  			if (ssif_info->max_recv_msg_size > 62)
  				ssif_info->max_recv_msg_size = 62;
  			break;
  
  		case SSIF_MULTI_n_PART:
  			/* We take whatever size given, but do some testing. */
  			break;
  
  		default:
  			/* Data is not sane, just give up. */
  			goto no_support;
  		}
  	} else {
   no_support:
  		/* Assume no multi-part or PEC support */
  		pr_info("Error fetching SSIF: %d %d %2.2x, your system probably doesn't support this command so using defaults\n",
  			rv, len, resp[2]);
  
  		ssif_info->max_xmit_msg_size = 32;
  		ssif_info->max_recv_msg_size = 32;
  		ssif_info->multi_support = SSIF_NO_MULTI;
  		ssif_info->supports_pec = 0;
  	}
  
  	test_multipart_messages(client, ssif_info, resp);
  
  	/* Make sure the NMI timeout is cleared. */
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_CLEAR_MSG_FLAGS_CMD;
  	msg[2] = WDT_PRE_TIMEOUT_INT;
  	rv = do_cmd(client, 3, msg, &len, resp);
  	if (rv || (len < 3) || (resp[2] != 0))
  		pr_warn("Unable to clear message flags: %d %d %2.2x\n",
  			rv, len, resp[2]);
  
  	/* Attempt to enable the event buffer. */
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_GET_BMC_GLOBAL_ENABLES_CMD;
  	rv = do_cmd(client, 2, msg, &len, resp);
  	if (rv || (len < 4) || (resp[2] != 0)) {
  		pr_warn("Error getting global enables: %d %d %2.2x\n",
  			rv, len, resp[2]);
  		rv = 0; /* Not fatal */
  		goto found;
  	}
  
  	ssif_info->global_enables = resp[3];
  
  	if (resp[3] & IPMI_BMC_EVT_MSG_BUFF) {
  		ssif_info->has_event_buffer = true;
  		/* buffer is already enabled, nothing to do. */
  		goto found;
  	}
  
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
  	msg[2] = ssif_info->global_enables | IPMI_BMC_EVT_MSG_BUFF;
  	rv = do_cmd(client, 3, msg, &len, resp);
  	if (rv || (len < 2)) {
  		pr_warn("Error setting global enables: %d %d %2.2x\n",
  			rv, len, resp[2]);
  		rv = 0; /* Not fatal */
  		goto found;
  	}
  
  	if (resp[2] == 0) {
  		/* A successful return means the event buffer is supported. */
  		ssif_info->has_event_buffer = true;
  		ssif_info->global_enables |= IPMI_BMC_EVT_MSG_BUFF;
  	}
  
  	/* Some systems don't behave well if you enable alerts. */
  	if (alerts_broken)
  		goto found;
  
  	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
  	msg[1] = IPMI_SET_BMC_GLOBAL_ENABLES_CMD;
  	msg[2] = ssif_info->global_enables | IPMI_BMC_RCV_MSG_INTR;
  	rv = do_cmd(client, 3, msg, &len, resp);
  	if (rv || (len < 2)) {
  		pr_warn("Error setting global enables: %d %d %2.2x\n",
  			rv, len, resp[2]);
  		rv = 0; /* Not fatal */
  		goto found;
  	}
  
  	if (resp[2] == 0) {
  		/* A successful return means the alert is supported. */
  		ssif_info->supports_alert = true;
  		ssif_info->global_enables |= IPMI_BMC_RCV_MSG_INTR;
  	}
  
   found:
  	if (ssif_dbg_probe) {
  		pr_info("ssif_probe: i2c_probe found device at i2c address %x\n",
  			client->addr);
  	}
  
  	spin_lock_init(&ssif_info->lock);
  	ssif_info->ssif_state = SSIF_NORMAL;
  	timer_setup(&ssif_info->retry_timer, retry_timeout, 0);
  
  	for (i = 0; i < SSIF_NUM_STATS; i++)
  		atomic_set(&ssif_info->stats[i], 0);
  
  	if (ssif_info->supports_pec)
  		ssif_info->client->flags |= I2C_CLIENT_PEC;
  
  	ssif_info->handlers.owner = THIS_MODULE;
  	ssif_info->handlers.start_processing = ssif_start_processing;
  	ssif_info->handlers.shutdown = shutdown_ssif;
  	ssif_info->handlers.get_smi_info = get_smi_info;
  	ssif_info->handlers.sender = sender;
  	ssif_info->handlers.request_events = request_events;
  
  	{
  		unsigned int thread_num;
  
  		thread_num = ((i2c_adapter_id(ssif_info->client->adapter)
  			       << 8) |
  			      ssif_info->client->addr);
  		init_completion(&ssif_info->wake_thread);
  		ssif_info->thread = kthread_run(ipmi_ssif_thread, ssif_info,
  					       "kssif%4.4x", thread_num);
  		if (IS_ERR(ssif_info->thread)) {
  			rv = PTR_ERR(ssif_info->thread);
  			dev_notice(&ssif_info->client->dev,
  				   "Could not start kernel thread: error %d\n",
  				   rv);
  			goto out;
  		}
  	}
  
  	dev_set_drvdata(&ssif_info->client->dev, ssif_info);
  	rv = device_add_group(&ssif_info->client->dev,
  			      &ipmi_ssif_dev_attr_group);
  	if (rv) {
  		dev_err(&ssif_info->client->dev,
  			"Unable to add device attributes: error %d\n",
  			rv);
  		goto out;
  	}
  
  	rv = ipmi_register_smi(&ssif_info->handlers,
  			       ssif_info,
  			       &ssif_info->client->dev,
  			       slave_addr);
  	 if (rv) {
  		pr_err("Unable to register device: error %d\n", rv);
  		goto out_remove_attr;
  	}
  
   out:
  	if (rv) {
  		if (addr_info)
  			addr_info->client = NULL;
  
  		dev_err(&client->dev, "Unable to start IPMI SSIF: %d\n", rv);
  		kfree(ssif_info);
  	}
  	kfree(resp);
  	return rv;
  
  out_remove_attr:
  	device_remove_group(&ssif_info->client->dev, &ipmi_ssif_dev_attr_group);
  	dev_set_drvdata(&ssif_info->client->dev, NULL);
  	goto out;
  }
  
  static int ssif_adapter_handler(struct device *adev, void *opaque)
  {
  	struct ssif_addr_info *addr_info = opaque;
  
  	if (adev->type != &i2c_adapter_type)
  		return 0;
  
  	addr_info->added_client = i2c_new_device(to_i2c_adapter(adev),
  						 &addr_info->binfo);
  
  	if (!addr_info->adapter_name)
  		return 1; /* Only try the first I2C adapter by default. */
  	return 0;
  }
  
  static int new_ssif_client(int addr, char *adapter_name,
  			   int debug, int slave_addr,
  			   enum ipmi_addr_src addr_src,
  			   struct device *dev)
  {
  	struct ssif_addr_info *addr_info;
  	int rv = 0;
  
  	mutex_lock(&ssif_infos_mutex);
  	if (ssif_info_find(addr, adapter_name, false)) {
  		rv = -EEXIST;
  		goto out_unlock;
  	}
  
  	addr_info = kzalloc(sizeof(*addr_info), GFP_KERNEL);
  	if (!addr_info) {
  		rv = -ENOMEM;
  		goto out_unlock;
  	}
  
  	if (adapter_name) {
  		addr_info->adapter_name = kstrdup(adapter_name, GFP_KERNEL);
  		if (!addr_info->adapter_name) {
  			kfree(addr_info);
  			rv = -ENOMEM;
  			goto out_unlock;
  		}
  	}
  
  	strncpy(addr_info->binfo.type, DEVICE_NAME,
  		sizeof(addr_info->binfo.type));
  	addr_info->binfo.addr = addr;
  	addr_info->binfo.platform_data = addr_info;
  	addr_info->debug = debug;
  	addr_info->slave_addr = slave_addr;
  	addr_info->addr_src = addr_src;
  	addr_info->dev = dev;
  
  	if (dev)
  		dev_set_drvdata(dev, addr_info);
  
  	list_add_tail(&addr_info->link, &ssif_infos);
  
  	if (initialized)
  		i2c_for_each_dev(addr_info, ssif_adapter_handler);
  	/* Otherwise address list will get it */
  
  out_unlock:
  	mutex_unlock(&ssif_infos_mutex);
  	return rv;
  }
  
  static void free_ssif_clients(void)
  {
  	struct ssif_addr_info *info, *tmp;
  
  	mutex_lock(&ssif_infos_mutex);
  	list_for_each_entry_safe(info, tmp, &ssif_infos, link) {
  		list_del(&info->link);
  		kfree(info->adapter_name);
  		kfree(info);
  	}
  	mutex_unlock(&ssif_infos_mutex);
  }
  
  static unsigned short *ssif_address_list(void)
  {
  	struct ssif_addr_info *info;
  	unsigned int count = 0, i = 0;
  	unsigned short *address_list;
  
  	list_for_each_entry(info, &ssif_infos, link)
  		count++;
  
  	address_list = kcalloc(count + 1, sizeof(*address_list),
  			       GFP_KERNEL);
  	if (!address_list)
  		return NULL;
  
  	list_for_each_entry(info, &ssif_infos, link) {
  		unsigned short addr = info->binfo.addr;
  		int j;
  
  		for (j = 0; j < i; j++) {
  			if (address_list[j] == addr)
  				/* Found a dup. */
  				break;
  		}
  		if (j == i) /* Didn't find it in the list. */
  			address_list[i++] = addr;
  	}
  	address_list[i] = I2C_CLIENT_END;
  
  	return address_list;
  }
  
  #ifdef CONFIG_ACPI
  static const struct acpi_device_id ssif_acpi_match[] = {
  	{ "IPI0001", 0 },
  	{ },
  };
  MODULE_DEVICE_TABLE(acpi, ssif_acpi_match);
  #endif
  
  #ifdef CONFIG_DMI
  static int dmi_ipmi_probe(struct platform_device *pdev)
  {
  	u8 slave_addr = 0;
  	u16 i2c_addr;
  	int rv;
  
  	if (!ssif_trydmi)
  		return -ENODEV;
  
  	rv = device_property_read_u16(&pdev->dev, "i2c-addr", &i2c_addr);
  	if (rv) {
  		dev_warn(&pdev->dev, "No i2c-addr property\n");
  		return -ENODEV;
  	}
  
  	rv = device_property_read_u8(&pdev->dev, "slave-addr", &slave_addr);
  	if (rv)
  		dev_warn(&pdev->dev, "device has no slave-addr property");
  
  	return new_ssif_client(i2c_addr, NULL, 0,
  			       slave_addr, SI_SMBIOS, &pdev->dev);
  }
  #else
  static int dmi_ipmi_probe(struct platform_device *pdev)
  {
  	return -ENODEV;
  }
  #endif
  
  static const struct i2c_device_id ssif_id[] = {
  	{ DEVICE_NAME, 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, ssif_id);
  
  static struct i2c_driver ssif_i2c_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver		= {
  		.name			= DEVICE_NAME
  	},
  	.probe		= ssif_probe,
  	.remove		= ssif_remove,
  	.alert		= ssif_alert,
  	.id_table	= ssif_id,
  	.detect		= ssif_detect
  };
  
  static int ssif_platform_probe(struct platform_device *dev)
  {
  	return dmi_ipmi_probe(dev);
  }
  
  static int ssif_platform_remove(struct platform_device *dev)
  {
  	struct ssif_addr_info *addr_info = dev_get_drvdata(&dev->dev);
  
  	if (!addr_info)
  		return 0;
  
  	mutex_lock(&ssif_infos_mutex);
  	i2c_unregister_device(addr_info->added_client);
  
  	list_del(&addr_info->link);
  	kfree(addr_info);
  	mutex_unlock(&ssif_infos_mutex);
  	return 0;
  }
  
  static const struct platform_device_id ssif_plat_ids[] = {
      { "dmi-ipmi-ssif", 0 },
      { }
  };
  
  static struct platform_driver ipmi_driver = {
  	.driver = {
  		.name = DEVICE_NAME,
  	},
  	.probe		= ssif_platform_probe,
  	.remove		= ssif_platform_remove,
  	.id_table       = ssif_plat_ids
  };
  
  static int init_ipmi_ssif(void)
  {
  	int i;
  	int rv;
  
  	if (initialized)
  		return 0;
  
  	pr_info("IPMI SSIF Interface driver\n");
  
  	/* build list for i2c from addr list */
  	for (i = 0; i < num_addrs; i++) {
  		rv = new_ssif_client(addr[i], adapter_name[i],
  				     dbg[i], slave_addrs[i],
  				     SI_HARDCODED, NULL);
  		if (rv)
  			pr_err("Couldn't add hardcoded device at addr 0x%x\n",
  			       addr[i]);
  	}
  
  	if (ssif_tryacpi)
  		ssif_i2c_driver.driver.acpi_match_table	=
  			ACPI_PTR(ssif_acpi_match);
  
  	if (ssif_trydmi) {
  		rv = platform_driver_register(&ipmi_driver);
  		if (rv)
  			pr_err("Unable to register driver: %d\n", rv);
  	}
  
  	ssif_i2c_driver.address_list = ssif_address_list();
  
  	rv = i2c_add_driver(&ssif_i2c_driver);
  	if (!rv)
  		initialized = true;
  
  	return rv;
  }
  module_init(init_ipmi_ssif);
  
  static void cleanup_ipmi_ssif(void)
  {
  	if (!initialized)
  		return;
  
  	initialized = false;
  
  	i2c_del_driver(&ssif_i2c_driver);
  
  	kfree(ssif_i2c_driver.address_list);
  
  	platform_driver_unregister(&ipmi_driver);
  
  	free_ssif_clients();
  }
  module_exit(cleanup_ipmi_ssif);
  
  MODULE_ALIAS("platform:dmi-ipmi-ssif");
  MODULE_AUTHOR("Todd C Davis <todd.c.davis@intel.com>, Corey Minyard <minyard@acm.org>");
  MODULE_DESCRIPTION("IPMI driver for management controllers on a SMBus");
  MODULE_LICENSE("GPL");
  