Quelle  ipmi_ssif.c   Sprache: C

// 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.
 */

#define pr_fmt(fmt) "ipmi_ssif: " fmt
#define dev_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_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  60000 /* 60ms between message tries (T3). */
#define SSIF_REQ_RETRY_USEC 60000 /* 60ms between send retries (T6). */
#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_REQ_RETRY_MSEC (SSIF_REQ_RETRY_USEC / 1000)
#define SSIF_MSG_JIFFIES ((SSIF_MSG_USEC * 1000) / TICK_NSEC)
#define SSIF_REQ_RETRY_JIFFIES ((SSIF_REQ_RETRY_USEC * 1000) / TICK_NSEC)
#define SSIF_MSG_PART_JIFFIES ((SSIF_MSG_PART_USEC * 1000) / TICK_NSEC)

/*
 * Timeout for the watch, only used for get flag timer.
 */
#define SSIF_WATCH_MSG_TIMEOUT  msecs_to_jiffies(10)
#define SSIF_WATCH_WATCHDOG_TIMEOUT msecs_to_jiffies(250)

enum ssif_intf_state {
 SSIF_IDLE,
 SSIF_GETTING_FLAGS,
 SSIF_GETTING_EVENTS,
 SSIF_CLEARING_FLAGS,
 SSIF_GETTING_MESSAGES,
 /* FIXME - add watchdog stuff. */
};

#define IS_SSIF_IDLE(ssif) ((ssif)->ssif_state == SSIF_IDLE \
       && (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 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;

 /* Used to inform the timeout that it should do a resend. */
 bool      do_resend;

 /*
 * 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 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;

 long watch_timeout;  /* Timeout for flags check, 0 if off. */
 struct timer_list watch_timer; /* Flag fetch timer. */

 /* 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 bool platform_registered;

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)
 __acquires(&ssif_info->lock)
{
 spin_lock_irqsave(&ssif_info->lock, *flags);
 return flags;
}

static void ipmi_ssif_unlock_cond(struct ssif_info *ssif_info,
      unsigned long *flags)
 __releases(&ssif_info->lock)
{
 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);
  dev_err(&ssif_info->client->dev,
   "%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 IS_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_IDLE;
 }
}

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_IDLE;
}

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_IDLE;
  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_IDLE;
  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_IDLE;
  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 IS_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_IDLE;
  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 (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 void 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);
}


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)
{
 ssif_info->multi_pos = 0;

 ssif_i2c_send(ssif_info, msg_done_handler, I2C_SMBUS_READ,
    SSIF_IPMI_RESPONSE,
    ssif_info->recv, I2C_SMBUS_BLOCK_DATA);
}

static void start_resend(struct ssif_info *ssif_info);

static void retry_timeout(struct timer_list *t)
{
 struct ssif_info *ssif_info = timer_container_of(ssif_info, t,
        retry_timer);
 unsigned long oflags, *flags;
 bool waiting, resend;

 if (ssif_info->stopping)
  return;

 flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
 resend = ssif_info->do_resend;
 ssif_info->do_resend = false;
 waiting = ssif_info->waiting_alert;
 ssif_info->waiting_alert = false;
 ipmi_ssif_unlock_cond(ssif_info, flags);

 if (waiting)
  start_get(ssif_info);
 if (resend) {
  start_resend(ssif_info);
  ssif_inc_stat(ssif_info, send_retries);
 }
}

static void watch_timeout(struct timer_list *t)
{
 struct ssif_info *ssif_info = timer_container_of(ssif_info, t,
        watch_timer);
 unsigned long oflags, *flags;

 if (ssif_info->stopping)
  return;

 flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
 if (ssif_info->watch_timeout) {
  mod_timer(&ssif_info->watch_timer,
     jiffies + ssif_info->watch_timeout);
  if (IS_SSIF_IDLE(ssif_info)) {
   start_flag_fetch(ssif_info, flags); /* Releases lock */
   return;
  }
  ssif_info->req_flags = true;
 }
 ipmi_ssif_unlock_cond(ssif_info, flags);
}

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;
  timer_delete(&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 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;

 /*
 * 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;
   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)
   dev_dbg(&ssif_info->client->dev,
    "%s: Error %d\n", __func__, 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;

  ssif_i2c_send(ssif_info, msg_done_handler, I2C_SMBUS_READ,
    SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE,
    ssif_info->recv, I2C_SMBUS_BLOCK_DATA);
  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)
    dev_dbg(&ssif_info->client->dev,
     "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)
    dev_dbg(&ssif_info->client->dev,
     "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)
    dev_dbg(&ssif_info->client->dev,
     "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 + 1 != 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.
 */
   if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
    dev_dbg(&ssif_info->client->dev,
     "Received message out of sequence, expected %u, got %u\n",
     ssif_info->multi_pos - 1, blocknum);
   result = -EIO;
  } else {
   ssif_inc_stat(ssif_info, received_message_parts);

   ssif_info->multi_pos++;

   ssif_i2c_send(ssif_info, msg_done_handler,
      I2C_SMBUS_READ,
      SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE,
      ssif_info->recv,
      I2C_SMBUS_BLOCK_DATA);
   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)
  dev_dbg(&ssif_info->client->dev,
   "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) {
  if (data) {
   if (len > IPMI_MAX_MSG_LENGTH)
    len = IPMI_MAX_MSG_LENGTH;
   memcpy(msg->rsp, data, len);
  } else {
   len = 0;
  }
  msg->rsp_size = len;
  ssif_info->curr_msg = NULL;
 }

 switch (ssif_info->ssif_state) {
 case SSIF_IDLE:
  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_IDLE;
   ipmi_ssif_unlock_cond(ssif_info, flags);
   dev_warn(&ssif_info->client->dev,
     "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) {
   /*
 * Recv error response, give up.
 */
   ssif_info->ssif_state = SSIF_IDLE;
   ipmi_ssif_unlock_cond(ssif_info, flags);
   dev_warn(&ssif_info->client->dev,
     "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 */
   dev_warn(&ssif_info->client->dev,
     "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) {
   dev_warn(&ssif_info->client->dev,
     "Invalid response clearing flags: %x %x\n",
     data[0], data[1]);
  }
  ssif_info->ssif_state = SSIF_IDLE;
  ipmi_ssif_unlock_cond(ssif_info, flags);
  break;

 case SSIF_GETTING_EVENTS:
  if (!msg) {
   /* Should never happen, but just in case. */
   dev_warn(&ssif_info->client->dev,
     "No message set while getting events\n");
   ipmi_ssif_unlock_cond(ssif_info, flags);
   break;
  }

  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) {
   dev_warn(&ssif_info->client->dev,
     "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 (!msg) {
   /* Should never happen, but just in case. */
   dev_warn(&ssif_info->client->dev,
     "No message set while getting messages\n");
   ipmi_ssif_unlock_cond(ssif_info, flags);
   break;
  }

  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) {
   dev_warn(&ssif_info->client->dev,
     "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;

 default:
  /* Should never happen, but just in case. */
  dev_warn(&ssif_info->client->dev,
    "Invalid state in message done handling: %d\n",
    ssif_info->ssif_state);
  ipmi_ssif_unlock_cond(ssif_info, flags);
 }

 flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
 if (IS_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)
  dev_dbg(&ssif_info->client->dev,
   "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)
{
 /* We are single-threaded here, so no need for a lock. */
 if (result < 0) {
  ssif_info->retries_left--;
  if (ssif_info->retries_left > 0) {
   /*
 * Wait the retry timeout time per the spec,
 * then redo the send.
 */
   ssif_info->do_resend = true;
   mod_timer(&ssif_info->retry_timer,
      jiffies + SSIF_REQ_RETRY_JIFFIES);
   return;
  }

  ssif_inc_stat(ssif_info, send_errors);

  if (ssif_info->ssif_debug & SSIF_DEBUG_MSG)
   dev_dbg(&ssif_info->client->dev,
    "%s: Out of retries\n", __func__);

  msg_done_handler(ssif_info, -EIO, 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;
  }

  ssif_i2c_send(ssif_info, msg_written_handler,
     I2C_SMBUS_WRITE, cmd,
     data_to_send, I2C_SMBUS_BLOCK_DATA);
 } 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 jiffy then request the next message */
   ssif_info->waiting_alert = true;
   ssif_info->retries_left = SSIF_RECV_RETRIES;
   if (!ssif_info->stopping)
    mod_timer(&ssif_info->retry_timer,
       jiffies + SSIF_MSG_PART_JIFFIES);
   ipmi_ssif_unlock_cond(ssif_info, flags);
  }
 }
}

static void start_resend(struct ssif_info *ssif_info)
{
 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;
 }

 ssif_i2c_send(ssif_info, msg_written_handler, I2C_SMBUS_WRITE,
     command, ssif_info->data, I2C_SMBUS_BLOCK_DATA);
}

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;
 start_resend(ssif_info);
 return 0;
}

/* 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 (!IS_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 = 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);
  dev_dbg(&ssif_info->client->dev,
   "**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;
}

/*
 * Upper layer wants us to request events.
 */
static void request_events(void *send_info)
{
 struct ssif_info *ssif_info = send_info;
 unsigned long oflags, *flags;

 if (!ssif_info->has_event_buffer)
  return;

 flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
 ssif_info->req_events = true;
 ipmi_ssif_unlock_cond(ssif_info, flags);
}

/*
 * Upper layer is changing the flag saying whether we need to request
 * flags periodically or not.
 */
static void ssif_set_need_watch(void *send_info, unsigned int watch_mask)
{
 struct ssif_info *ssif_info = send_info;
 unsigned long oflags, *flags;
 long timeout = 0;

 if (watch_mask & IPMI_WATCH_MASK_CHECK_MESSAGES)
  timeout = SSIF_WATCH_MSG_TIMEOUT;
 else if (watch_mask)
  timeout = SSIF_WATCH_WATCHDOG_TIMEOUT;

 flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
 if (timeout != ssif_info->watch_timeout) {
  ssif_info->watch_timeout = timeout;
  if (ssif_info->watch_timeout)
   mod_timer(&ssif_info->watch_timer,
      jiffies + ssif_info->watch_timeout);
 }
 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 sysfs_emit(buf, "%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 sysfs_emit(buf, "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_IDLE)
  schedule_timeout(1);

 ssif_info->stopping = true;
 timer_delete_sync(&ssif_info->watch_timer);
 timer_delete_sync(&ssif_info->retry_timer);
 if (ssif_info->thread)
  kthread_stop(ssif_info->thread);
}

static void ssif_remove(struct i2c_client *client)
{
 struct ssif_info *ssif_info = i2c_get_clientdata(client);
 struct ssif_addr_info *addr_info;

 /*
 * After this point, we won't deliver anything asynchronously
 * 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);
}

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) {
   msleep(SSIF_REQ_RETRY_MSEC);
   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 {
     if (len < 3) {
  rv = -ENODEV;
     } else {
  struct ipmi_device_id id;

  rv = ipmi_demangle_device_id(resp[0] >> 2, resp[1],
          resp + 2, len - 2, &id);
  if (rv)
      rv = -ENODEV; /* Error means a BMC probably isn't there. */
     }
     if (!rv && info)
  strscpy(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->addr_src == SI_SMBIOS && !info->adapter_name)
    info->adapter_name = kstrdup(adapter_name,
            GFP_KERNEL);

   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;
  request_module_nowait("acpi_ipmi");
  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) {
   msleep(SSIF_REQ_RETRY_MSEC);
   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 void ssif_remove_dup(struct i2c_client *client)
{
 struct ssif_info *ssif_info = i2c_get_clientdata(client);

 ipmi_unregister_smi(ssif_info->intf);
 kfree(ssif_info);
}

static int ssif_add_infos(struct i2c_client *client)
{
 struct ssif_addr_info *info;

 info = kzalloc(sizeof(*info), GFP_KERNEL);
 if (!info)
  return -ENOMEM;
 info->addr_src = SI_ACPI;
 info->client = client;
 info->adapter_name = kstrdup(client->adapter->name, GFP_KERNEL);
 if (!info->adapter_name) {
  kfree(info);
  return -ENOMEM;
 }

 info->binfo.addr = client->addr;
 list_add_tail(&info->link, &ssif_infos);
 return 0;
}

/*
 * Prefer ACPI over SMBIOS, if both are available.
 * So if we get an ACPI interface and have already registered a SMBIOS
 * interface at the same address, remove the SMBIOS and add the ACPI one.
 */
static int ssif_check_and_remove(struct i2c_client *client,
         struct ssif_info *ssif_info)
{
 struct ssif_addr_info *info;

 list_for_each_entry(info, &ssif_infos, link) {
  if (!info->client)
   return 0;
  if (!strcmp(info->adapter_name, client->adapter->name) &&
      info->binfo.addr == client->addr) {
   if (info->addr_src == SI_ACPI)
    return -EEXIST;

   if (ssif_info->addr_source == SI_ACPI &&
       info->addr_src == SI_SMBIOS) {
    dev_info(&client->dev,
      "Removing %s-specified SSIF interface in favor of ACPI\n",
      ipmi_addr_src_to_str(info->addr_src));
    ssif_remove_dup(info->client);
    return 0;
   }
  }
 }
 return 0;
}

static int ssif_probe(struct i2c_client *client)
{
 unsigned char     msg[3];
 unsigned char     *resp;
 struct ssif_info   *ssif_info;
 int               rv = 0;
 int               len = 0;
 int               i;
 u8    slave_addr = 0;
 struct ssif_addr_info *addr_info = NULL;

 mutex_lock(&ssif_infos_mutex);
 resp = kmalloc(IPMI_MAX_MSG_LENGTH, GFP_KERNEL);
 if (!resp) {
  mutex_unlock(&ssif_infos_mutex);
  return -ENOMEM;
 }

 ssif_info = kzalloc(sizeof(*ssif_info), GFP_KERNEL);
 if (!ssif_info) {
  kfree(resp);
  mutex_unlock(&ssif_infos_mutex);
  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;
  }
 }

 ssif_info->client = client;
 i2c_set_clientdata(client, ssif_info);

 rv = ssif_check_and_remove(client, ssif_info);
 /* If rv is 0 and addr source is not SI_ACPI, continue probing */
 if (!rv && ssif_info->addr_source == SI_ACPI) {
  rv = ssif_add_infos(client);
  if (rv) {
   dev_err(&client->dev, "Out of memory!, exiting ..\n");
   goto out;
  }
 } else if (rv) {
  dev_err(&client->dev, "Not probing, Interface already present\n");
  goto out;
 }

 slave_addr = find_slave_address(client, slave_addr);

 dev_info(&client->dev,
   "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);

 /*
 * Send a get device id command and validate its response to
 * make sure a valid BMC is there.
 */
 rv = ssif_detect(client, NULL);
 if (rv) {
  dev_err(&client->dev, "Not present\n");
  goto out;
 }

 /* 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)
    dev_dbg(&ssif_info->client->dev,
     "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 */
  dev_info(&ssif_info->client->dev,
    "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))
  dev_warn(&ssif_info->client->dev,
    "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)) {
  dev_warn(&ssif_info->client->dev,
    "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)) {
  dev_warn(&ssif_info->client->dev,
    "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)) {
  dev_warn(&ssif_info->client->dev,
    "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) {
  dev_dbg(&ssif_info->client->dev,
         "%s: i2c_probe found device at i2c address %x\n",
         __func__, client->addr);
 }

 spin_lock_init(&ssif_info->lock);
 ssif_info->ssif_state = SSIF_IDLE;
 timer_setup(&ssif_info->retry_timer, retry_timeout, 0);
 timer_setup(&ssif_info->watch_timer, watch_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;
 ssif_info->handlers.set_need_watch = ssif_set_need_watch;

 {
  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) {
  dev_err(&ssif_info->client->dev,
   "Unable to register device: error %d\n", rv);
  goto out_remove_attr;
 }

 out:
 if (rv) {
  if (addr_info)
   addr_info->client = NULL;

  dev_err(&ssif_info->client->dev,
   "Unable to start IPMI SSIF: %d\n", rv);
  i2c_set_clientdata(client, NULL);
  kfree(ssif_info);
 }
 kfree(resp);
 mutex_unlock(&ssif_infos_mutex);
 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 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;
  }
 }

 strscpy(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);

 /* 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)
  slave_addr = 0x20;

 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 },
 { }
};
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 void ssif_platform_remove(struct platform_device *dev)
{
 struct ssif_addr_info *addr_info = dev_get_drvdata(&dev->dev);

 mutex_lock(&ssif_infos_mutex);
 list_del(&addr_info->link);
 kfree(addr_info);
 mutex_unlock(&ssif_infos_mutex);
}

static const struct platform_device_id ssif_plat_ids[] = {
    { "dmi-ipmi-ssif", 0 },
    { }
};
MODULE_DEVICE_TABLE(platform, ssif_plat_ids);

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 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);
  else
   platform_registered = true;
 }

 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 __exit cleanup_ipmi_ssif(void)
{
 if (!initialized)
  return;

 initialized = false;

 i2c_del_driver(&ssif_i2c_driver);

 kfree(ssif_i2c_driver.address_list);

 if (ssif_trydmi && platform_registered)
  platform_driver_unregister(&ipmi_driver);

 free_ssif_clients();
}
module_exit(cleanup_ipmi_ssif);

MODULE_ALIAS("platform:dmi-ipmi-ssif");
MODULE_AUTHOR("Todd C Davis , Corey Minyard ");
MODULE_DESCRIPTION("IPMI driver for management controllers on a SMBus");
MODULE_LICENSE("GPL");