ipmi: Add SMBus interface driver (SSIF)

This patch adds the SMBus interface to the IPMI driver.

Signed-off-by: Corey Minyard <minyard@acm.org>

 Documentation/IPMI.txt       |   32
 drivers/char/ipmi/Kconfig    |   11
 drivers/char/ipmi/Makefile   |    1
 drivers/char/ipmi/ipmi_smb.c | 1737 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 1769 insertions(+), 12 deletions(-)

3 files changed, 1879 insertions, 0 deletions

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index db1c9b7adaa6..809d28328c6f 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -62,6 +62,14 @@ config IPMI_SI_PROBE_DEFAULTS
 	 only be available on older systems if the "ipmi_si_intf.trydefaults=1"
 	 boot argument is passed.
 
+config IPMI_SSIF
+       tristate 'IPMI SMBus handler (SSIF)'
+       select I2C
+       help
+         Provides a driver for a SMBus interface to a BMC, meaning that you
+	 have a driver that must be accessed over an I2C bus instead of a
+	 standard interface.  This module requires I2C support.
+
 config IPMI_WATCHDOG
        tristate 'IPMI Watchdog Timer'
        help
diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile
index 16a93648d54e..115c08da7117 100644
--- a/drivers/char/ipmi/Makefile
+++ b/drivers/char/ipmi/Makefile
@@ -7,5 +7,6 @@ ipmi_si-y := ipmi_si_intf.o ipmi_kcs_sm.o ipmi_smic_sm.o ipmi_bt_sm.o
 obj-$(CONFIG_IPMI_HANDLER) += ipmi_msghandler.o
 obj-$(CONFIG_IPMI_DEVICE_INTERFACE) += ipmi_devintf.o
 obj-$(CONFIG_IPMI_SI) += ipmi_si.o
+obj-$(CONFIG_IPMI_SSIF) += ipmi_ssif.o
 obj-$(CONFIG_IPMI_WATCHDOG) += ipmi_watchdog.o
 obj-$(CONFIG_IPMI_POWEROFF) += ipmi_poweroff.o
diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
new file mode 100644
index 000000000000..e178ac27e73c
--- /dev/null
+++ b/drivers/char/ipmi/ipmi_ssif.c
@@ -0,0 +1,1870 @@
+/*
+ * 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 program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ */
+
+/*
+ * 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.
+ */
+
+#include <linux/version.h>
+#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>
+
+#define PFX "ipmi_ssif: "
+#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_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,
+
+	/* Always add statistics before this value, it must be last. */
+	SSIF_NUM_STATS
+};
+
+struct ssif_addr_info {
+	unsigned short addr;
+	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 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 {
+	ipmi_smi_t          intf;
+	int                 intf_num;
+	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;
+
+	bool		    has_event_buffer;
+
+	/*
+	 * 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;
+
+	/* From the device id response. */
+	struct ipmi_device_id device_id;
+
+	struct timer_list retry_timer;
+	int retries_left;
+
+	/* Info from SSIF cmd */
+	unsigned char max_xmit_msg_size;
+	unsigned char max_recv_msg_size;
+	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 atomic_t next_intf = ATOMIC_INIT(0);
+
+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)
+{
+	ipmi_smi_t    intf = ssif_info->intf;
+
+	if (!intf) {
+		ipmi_free_smi_msg(msg);
+	} else if (msg->rsp_size < 0) {
+		return_hosed_msg(ssif_info, msg);
+		pr_err(PFX
+		       "Malformed message in deliver_recv_msg: rsp_size = %d\n",
+		       msg->rsp_size);
+	} else {
+		ipmi_smi_msg_received(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;
+		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;
+		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) {
+		ipmi_smi_t intf = ssif_info->intf;
+		/* Watchdog pre-timeout */
+		ssif_inc_stat(ssif_info, watchdog_pretimeouts);
+		start_clear_flags(ssif_info, flags);
+		if (intf)
+			ipmi_smi_watchdog_pretimeout(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 */
+		wait_for_completion(&ssif_info->wake_thread);
+		init_completion(&ssif_info->wake_thread);
+
+		if (ssif_info->stopping)
+			break;
+
+		if (ssif_info->i2c_read_write == I2C_SMBUS_WRITE) {
+			result = i2c_smbus_write_block_data(
+				ssif_info->client, SSIF_IPMI_REQUEST,
+				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_IPMI_RESPONSE,
+				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 retry_timeout(unsigned long data)
+{
+	struct ssif_info *ssif_info = (void *) data;
+	int rv;
+
+	if (ssif_info->stopping)
+		return;
+
+	ssif_info->rtc_us_timer = 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 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);
+
+			mod_timer(&ssif_info->retry_timer,
+				  jiffies + SSIF_MSG_JIFFIES);
+			ssif_info->rtc_us_timer = SSIF_MSG_USEC;
+			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. */
+		for (i = 0; i < (len-2); i++)
+			ssif_info->data[i] = data[i+2];
+		len -= 2;
+		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(PFX "Middle message with no data\n");
+
+			goto continue_op;
+		}
+
+		blocknum = data[ssif_info->multi_len];
+
+		if (ssif_info->multi_len+len-1 > 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;
+		}
+
+		/* Remove the blocknum from the data. */
+		for (i = 0; i < (len-1); i++)
+			ssif_info->data[i+ssif_info->multi_len] = data[i+1];
+		len--;
+		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.
+			 */
+			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(PFX
+						"Error from i2c_non_blocking_op(2)\n");
+
+				result = -EIO;
+			} else
+				return;
+		}
+	}
+
+	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);
+	}
+
+
+ continue_op:
+	if (ssif_info->ssif_debug & SSIF_DEBUG_STATE)
+		pr_info(PFX "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(PFX "Error getting flags: %d %d, %x\n",
+			       result, len, data[2]);
+		} else if (data[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
+			   || data[1] != IPMI_GET_MSG_FLAGS_CMD) {
+			pr_warn(PFX "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(PFX "Error clearing flags: %d %d, %x\n",
+			       result, len, data[2]);
+		} else if (data[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
+			   || data[1] != IPMI_CLEAR_MSG_FLAGS_CMD) {
+			pr_warn(PFX "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(PFX "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(PFX "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(PFX "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(PFX
+					"Out of retries in msg_written_handler\n");
+			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. */
+		int left;
+
+		ssif_inc_stat(ssif_info, sent_messages_parts);
+
+		left = ssif_info->multi_len - ssif_info->multi_pos;
+		if (left > 32)
+			left = 32;
+		/* Length byte. */
+		ssif_info->multi_data[ssif_info->multi_pos] = left;
+		ssif_info->multi_pos += left;
+		if (left < 32)
+			/*
+			 * Write is finished.  Note that we must end
+			 * with a write of less than 32 bytes to
+			 * complete the transaction, even if it is
+			 * zero bytes.
+			 */
+			ssif_info->multi_data = NULL;
+
+		rv = ssif_i2c_send(ssif_info, msg_written_handler,
+				  I2C_SMBUS_WRITE,
+				  SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
+				  ssif_info->multi_data + ssif_info->multi_pos,
+				  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 {
+		ssif_inc_stat(ssif_info, sent_messages);
+		ssif_inc_stat(ssif_info, sent_messages_parts);
+
+		/* Wait a jiffie then request the next message */
+		ssif_info->retries_left = SSIF_RECV_RETRIES;
+		ssif_info->rtc_us_timer = SSIF_MSG_PART_USEC;
+		mod_timer(&ssif_info->retry_timer,
+			  jiffies + SSIF_MSG_PART_JIFFIES);
+		return;
+	}
+}
+
+static int start_resend(struct ssif_info *ssif_info)
+{
+	int rv;
+	int command;
+
+	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 timeval t;
+
+		do_gettimeofday(&t);
+		pr_info("**Enqueue %02x %02x: %ld.%6.6ld\n",
+		       msg->data[0], msg->data[1], t.tv_sec, t.tv_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 inc_usecount(void *send_info)
+{
+	struct ssif_info *ssif_info = send_info;
+
+	if (!i2c_get_adapter(ssif_info->client->adapter->nr))
+		return -ENODEV;
+
+	i2c_use_client(ssif_info->client);
+	return 0;
+}
+
+static void dec_usecount(void *send_info)
+{
+	struct ssif_info *ssif_info = send_info;
+
+	i2c_release_client(ssif_info->client);
+	i2c_put_adapter(ssif_info->client->adapter);
+}
+
+static int ssif_start_processing(void *send_info,
+				 ipmi_smi_t 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.");
+
+/*
+ * 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 int use_thread;
+module_param(use_thread, int, 0);
+MODULE_PARM_DESC(use_thread, "Use the thread interface.");
+
+static bool ssif_tryacpi = 1;
+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 = 1;
+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);
+
+static int ssif_remove(struct i2c_client *client)
+{
+	struct ssif_info *ssif_info = i2c_get_clientdata(client);
+	int rv;
+
+	if (!ssif_info)
+		return 0;
+
+	i2c_set_clientdata(client, NULL);
+
+	/*
+	 * After this point, we won't deliver anything asychronously
+	 * to the message handler.  We can unregister ourself.
+	 */
+	rv = ipmi_unregister_smi(ssif_info->intf);
+	if (rv) {
+		pr_err(PFX "Unable to unregister device: errno=%d\n", rv);
+		return rv;
+	}
+	ssif_info->intf = 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);
+	}
+
+	/*
+	 * No message can be outstanding now, we have removed the
+	 * upper layer and it permitted us to do so.
+	 */
+	kfree(ssif_info);
+	return 0;
+}
+
+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 = -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;
+	}
+
+	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 {
+			*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 smi_type_proc_show(struct seq_file *m, void *v)
+{
+	return seq_puts(m, "ssif\n");
+}
+
+static int smi_type_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, smi_type_proc_show, inode->i_private);
+}
+
+static const struct file_operations smi_type_proc_ops = {
+	.open		= smi_type_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int smi_stats_proc_show(struct seq_file *m, void *v)
+{
+	struct ssif_info *ssif_info = m->private;
+
+	seq_printf(m, "sent_messages:          %u\n",
+		   ssif_get_stat(ssif_info, sent_messages));
+	seq_printf(m, "sent_messages_parts:    %u\n",
+		   ssif_get_stat(ssif_info, sent_messages_parts));
+	seq_printf(m, "send_retries:           %u\n",
+		   ssif_get_stat(ssif_info, send_retries));
+	seq_printf(m, "send_errors:            %u\n",
+		   ssif_get_stat(ssif_info, send_errors));
+	seq_printf(m, "received_messages:      %u\n",
+		   ssif_get_stat(ssif_info, received_messages));
+	seq_printf(m, "received_message_parts: %u\n",
+		   ssif_get_stat(ssif_info, received_message_parts));
+	seq_printf(m, "receive_retries:        %u\n",
+		   ssif_get_stat(ssif_info, receive_retries));
+	seq_printf(m, "receive_errors:         %u\n",
+		   ssif_get_stat(ssif_info, receive_errors));
+	seq_printf(m, "flag_fetches:           %u\n",
+		   ssif_get_stat(ssif_info, flag_fetches));
+	seq_printf(m, "hosed:                  %u\n",
+		   ssif_get_stat(ssif_info, hosed));
+	seq_printf(m, "events:                 %u\n",
+		   ssif_get_stat(ssif_info, events));
+	seq_printf(m, "watchdog_pretimeouts:   %u\n",
+		   ssif_get_stat(ssif_info, watchdog_pretimeouts));
+	return 0;
+}
+
+static int smi_stats_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, smi_stats_proc_show, PDE_DATA(inode));
+}
+
+static const struct file_operations smi_stats_proc_ops = {
+	.open		= smi_stats_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+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 (strcmp(info->adapter_name, adapter_name))
+					/* Names to 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 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;
+			slave_addr = addr_info->slave_addr;
+		}
+	}
+
+	pr_info(PFX "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);
+
+	/*
+	 * Do a Get Device ID command, since it comes back with some
+	 * useful info.
+	 */
+	msg[0] = IPMI_NETFN_APP_REQUEST << 2;
+	msg[1] = IPMI_GET_DEVICE_ID_CMD;
+	rv = do_cmd(client, 2, msg, &len, resp);
+	if (rv)
+		goto out;
+
+	rv = ipmi_demangle_device_id(resp, len, &ssif_info->device_id);
+	if (rv)
+		goto out;
+
+	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(PFX "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 > 64)
+				ssif_info->max_xmit_msg_size = 64;
+			if (ssif_info->max_recv_msg_size > 62)
+				ssif_info->max_recv_msg_size = 62;
+			break;
+
+		case SSIF_MULTI_n_PART:
+			break;
+
+		default:
+			/* Data is not sane, just give up. */
+			goto no_support;
+		}
+	} else {
+ no_support:
+		/* Assume no multi-part or PEC support */
+		pr_info(PFX "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;
+	}
+
+	/* 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(PFX "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(PFX "Error getting global enables: %d %d %2.2x\n",
+			rv, len, resp[2]);
+		rv = 0; /* Not fatal */
+		goto found;
+	}
+
+	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] = resp[3] | IPMI_BMC_EVT_MSG_BUFF;
+	rv = do_cmd(client, 3, msg, &len, resp);
+	if (rv || (len < 2)) {
+		pr_warn(PFX "Error getting 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;
+
+ found:
+	ssif_info->intf_num = atomic_inc_return(&next_intf);
+
+	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;
+	init_timer(&ssif_info->retry_timer);
+	ssif_info->retry_timer.data = (unsigned long) ssif_info;
+	ssif_info->retry_timer.function = retry_timeout;
+
+	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.get_smi_info = get_smi_info;
+	ssif_info->handlers.sender = sender;
+	ssif_info->handlers.request_events = request_events;
+	ssif_info->handlers.inc_usecount = inc_usecount;
+	ssif_info->handlers.dec_usecount = dec_usecount;
+
+	{
+		unsigned int thread_num;
+
+		thread_num = ((ssif_info->client->adapter->nr << 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;
+		}
+	}
+
+	rv = ipmi_register_smi(&ssif_info->handlers,
+			       ssif_info,
+			       &ssif_info->device_id,
+			       &ssif_info->client->dev,
+			       slave_addr);
+	 if (rv) {
+		pr_err(PFX "Unable to register device: error %d\n", rv);
+		goto out;
+	}
+
+	rv = ipmi_smi_add_proc_entry(ssif_info->intf, "type",
+				     &smi_type_proc_ops,
+				     ssif_info);
+	if (rv) {
+		pr_err(PFX "Unable to create proc entry: %d\n", rv);
+		goto out_err_unreg;
+	}
+
+	rv = ipmi_smi_add_proc_entry(ssif_info->intf, "ssif_stats",
+				     &smi_stats_proc_ops,
+				     ssif_info);
+	if (rv) {
+		pr_err(PFX "Unable to create proc entry: %d\n", rv);
+		goto out_err_unreg;
+	}
+
+ out:
+	if (rv)
+		kfree(ssif_info);
+	kfree(resp);
+	return rv;
+
+ out_err_unreg:
+	ipmi_unregister_smi(ssif_info->intf);
+	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;
+
+	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 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;
+
+	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;
+	unsigned short *address_list;
+
+	list_for_each_entry(info, &ssif_infos, link)
+		count++;
+
+	address_list = kzalloc(sizeof(*address_list) * (count + 1), GFP_KERNEL);
+	if (!address_list)
+		return NULL;
+
+	i = 0;
+	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)
+				goto skip_addr;
+		}
+		address_list[i] = addr;
+skip_addr:
+		i++;
+	}
+	address_list[i] = I2C_CLIENT_END;
+
+	return address_list;
+}
+
+#ifdef CONFIG_ACPI
+static struct acpi_device_id ssif_acpi_match[] = {
+	{ "IPI0001", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, ssif_acpi_match);
+
+/*
+ * Once we get an ACPI failure, we don't try any more, because we go
+ * through the tables sequentially.  Once we don't find a table, there
+ * are no more.
+ */
+static int acpi_failure;
+
+/*
+ * Defined in the IPMI 2.0 spec.
+ */
+struct SPMITable {
+	s8	Signature[4];
+	u32	Length;
+	u8	Revision;
+	u8	Checksum;
+	s8	OEMID[6];
+	s8	OEMTableID[8];
+	s8	OEMRevision[4];
+	s8	CreatorID[4];
+	s8	CreatorRevision[4];
+	u8	InterfaceType;
+	u8	IPMIlegacy;
+	s16	SpecificationRevision;
+
+	/*
+	 * Bit 0 - SCI interrupt supported
+	 * Bit 1 - I/O APIC/SAPIC
+	 */
+	u8	InterruptType;
+
+	/*
+	 * If bit 0 of InterruptType is set, then this is the SCI
+	 * interrupt in the GPEx_STS register.
+	 */
+	u8	GPE;
+
+	s16	Reserved;
+
+	/*
+	 * If bit 1 of InterruptType is set, then this is the I/O
+	 * APIC/SAPIC interrupt.
+	 */
+	u32	GlobalSystemInterrupt;
+
+	/* The actual register address. */
+	struct acpi_generic_address addr;
+
+	u8	UID[4];
+
+	s8      spmi_id[1]; /* A '\0' terminated array starts here. */
+};
+
+static int try_init_spmi(struct SPMITable *spmi)
+{
+	unsigned short myaddr;
+
+	if (num_addrs >= MAX_SSIF_BMCS)
+		return -1;
+
+	if (spmi->IPMIlegacy != 1) {
+		pr_warn("IPMI: Bad SPMI legacy: %d\n", spmi->IPMIlegacy);
+		return -ENODEV;
+	}
+
+	if (spmi->InterfaceType != 4)
+		return -ENODEV;
+
+	if (spmi->addr.space_id != ACPI_ADR_SPACE_SMBUS) {
+		pr_warn(PFX "Invalid ACPI SSIF I/O Address type: %d\n",
+			spmi->addr.space_id);
+		return -EIO;
+	}
+
+	myaddr = spmi->addr.address >> 1;
+
+	return new_ssif_client(myaddr, NULL, 0, 0, SI_SPMI);
+}
+
+static void spmi_find_bmc(void)
+{
+	acpi_status      status;
+	struct SPMITable *spmi;
+	int              i;
+
+	if (acpi_disabled)
+		return;
+
+	if (acpi_failure)
+		return;
+
+	for (i = 0; ; i++) {
+		status = acpi_get_table(ACPI_SIG_SPMI, i+1,
+					(struct acpi_table_header **)&spmi);
+		if (status != AE_OK)
+			return;
+
+		try_init_spmi(spmi);
+	}
+}
+#else
+static void spmi_find_bmc(void) { }
+#endif
+
+#ifdef CONFIG_DMI
+static int decode_dmi(const struct dmi_device *dmi_dev)
+{
+	struct dmi_header *dm = dmi_dev->device_data;
+	u8             *data = (u8 *) dm;
+	u8             len = dm->length;
+	unsigned short myaddr;
+	int            slave_addr;
+
+	if (num_addrs >= MAX_SSIF_BMCS)
+		return -1;
+
+	if (len < 9)
+		return -1;
+
+	if (data[0x04] != 4) /* Not SSIF */
+		return -1;
+
+	if ((data[8] >> 1) == 0) {
+		/*
+		 * Some broken systems put the I2C address in
+		 * the slave address field.  We try to
+		 * accommodate them here.
+		 */
+		myaddr = data[6] >> 1;
+		slave_addr = 0;
+	} else {
+		myaddr = data[8] >> 1;
+		slave_addr = data[6];
+	}
+
+	return new_ssif_client(myaddr, NULL, 0, 0, SI_SMBIOS);
+}
+
+static void dmi_iterator(void)
+{
+	const struct dmi_device *dev = NULL;
+
+	while ((dev = dmi_find_device(DMI_DEV_TYPE_IPMI, NULL, dev)))
+		decode_dmi(dev);
+}
+#else
+static void dmi_iterator(void) { }
+#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		= {
+		.owner			= THIS_MODULE,
+		.name			= DEVICE_NAME
+	},
+	.probe		= ssif_probe,
+	.remove		= ssif_remove,
+	.id_table	= ssif_id,
+	.detect		= ssif_detect
+};
+
+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);
+		if (!rv)
+			pr_err(PFX
+			       "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)
+		dmi_iterator();
+	if (ssif_tryacpi)
+		spmi_find_bmc();
+
+	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);
+
+	free_ssif_clients();
+}
+module_exit(cleanup_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");