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(-)

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
 ------------

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

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