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(-)

4 files changed, 1950 insertions, 3 deletions

diff --git a/Documentation/IPMI.txt b/Documentation/IPMI.txt
index f13c9132e9f2..653d5d739d7f 100644
--- a/Documentation/IPMI.txt
+++ b/Documentation/IPMI.txt
@@ -42,7 +42,13 @@ The driver interface depends on your hardware.  If your system
 properly provides the SMBIOS info for IPMI, the driver will detect it
 and just work.  If you have a board with a standard interface (These
 will generally be either "KCS", "SMIC", or "BT", consult your hardware
-manual), choose the 'IPMI SI handler' option.
+manual), choose the 'IPMI SI handler' option.  A driver also exists
+for direct I2C access to the IPMI management controller.  Some boards
+support this, but it is unknown if it will work on every board.  For
+this, choose 'IPMI SMBus handler', but be ready to try to do some
+figuring to see if it will work on your system if the SMBIOS/APCI
+information is wrong or not present.  It is fairly safe to have both
+these enabled and let the drivers auto-detect what is present.
 
 You should generally enable ACPI on your system, as systems with IPMI
 can have ACPI tables describing them.
@@ -52,7 +58,8 @@ their job correctly, the IPMI controller should be automatically
 detected (via ACPI or SMBIOS tables) and should just work.  Sadly,
 many boards do not have this information.  The driver attempts
 standard defaults, but they may not work.  If you fall into this
-situation, you need to read the section below named 'The SI Driver'.
+situation, you need to read the section below named 'The SI Driver' or
+"The SMBus Driver" on how to hand-configure your system.
 
 IPMI defines a standard watchdog timer.  You can enable this with the
 'IPMI Watchdog Timer' config option.  If you compile the driver into
@@ -97,7 +104,12 @@ driver, each open file for this device ties in to the message handler
 as an IPMI user.
 
 ipmi_si - A driver for various system interfaces.  This supports KCS,
-SMIC, and BT interfaces.
+SMIC, and BT interfaces.  Unless you have an SMBus interface or your
+own custom interface, you probably need to use this.
+
+ipmi_ssif - A driver for accessing BMCs on the SMBus. It uses the
+I2C kernel driver's SMBus interfaces to send and receive IPMI messages
+over the SMBus.
 
 ipmi_watchdog - IPMI requires systems to have a very capable watchdog
 timer.  This driver implements the standard Linux watchdog timer
@@ -476,6 +488,62 @@ for specifying an interface.  Note that when removing an interface,
 only the first three parameters (si type, address type, and address)
 are used for the comparison.  Any options are ignored for removing.
 
+The SMBus Driver (SSIF)
+-----------------------
+
+The SMBus driver allows up to 4 SMBus devices to be configured in the
+system.  By default, the driver will only register with something it
+finds in DMI or ACPI tables.  You can change this
+at module load time (for a module) with:
+
+  modprobe ipmi_ssif.o
+	addr=<i2caddr1>[,<i2caddr2>[,...]]
+	adapter=<adapter1>[,<adapter2>[...]]
+	dbg=<flags1>,<flags2>...
+        slave_addrs=<addr1>,<addr2>,...
+	[dbg_probe=1]
+
+The addresses are normal I2C addresses.  The adapter is the string
+name of the adapter, as shown in /sys/class/i2c-adapter/i2c-<n>/name.
+It is *NOT* i2c-<n> itself.
+
+The debug flags are bit flags for each BMC found, they are:
+IPMI messages: 1, driver state: 2, timing: 4, I2C probe: 8
+
+Setting dbg_probe to 1 will enable debugging of the probing and
+detection process for BMCs on the SMBusses.
+
+The slave_addrs specifies the IPMI address of the local BMC.  This is
+usually 0x20 and the driver defaults to that, but in case it's not, it
+can be specified when the driver starts up.
+
+Discovering the IPMI compliant BMC on the SMBus can cause devices on
+the I2C bus to fail. The SMBus driver writes a "Get Device ID" IPMI
+message as a block write to the I2C bus and waits for a response.
+This action can be detrimental to some I2C devices. It is highly
+recommended that the known I2C address be given to the SMBus driver in
+the smb_addr parameter unless you have DMI or ACPI data to tell the
+driver what to use.
+
+When compiled into the kernel, the addresses can be specified on the
+kernel command line as:
+
+  ipmb_ssif.addr=<i2caddr1>[,<i2caddr2>[...]]
+	ipmi_ssif.adapter=<adapter1>[,<adapter2>[...]]
+	ipmi_ssif.dbg=<flags1>[,<flags2>[...]]
+	ipmi_ssif.dbg_probe=1
+        ipmi_ssif.slave_addrs=<addr1>[,<addr2>[...]]
+
+These are the same options as on the module command line.
+
+The I2C driver does not support non-blocking access or polling, so
+this driver cannod to IPMI panic events, extend the watchdog at panic
+time, or other panic-related IPMI functions without special kernel
+patches and driver modifications.  You can get those at the openipmi
+web page.
+
+The driver supports a hot add and remove of interfaces through the I2C
+sysfs interface.
 
 Other Pieces
 ------------
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");