i2c: Adding support for Intel iSMT SMBus 2.0 host controller

The iSMT (Intel SMBus Message Transport) supports multi-master I2C/SMBus,
as well as IPMI.  It's operation is DMA-based and utilizes descriptors to
initiate transactions on the bus.

The iSMT hardware can act as both a master and a target, although this
driver only supports being a master.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Bill Brown <bill.e.brown@intel.com>
Tested-by: Seth Heasley <seth.heasley@intel.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>

Documentation/i2c/busses/i2c-ismt

+Kernel driver i2c-ismt
+
+Supported adapters:
+  * Intel S12xx series SOCs
+
+Authors:
+	Bill Brown <bill.e.brown@intel.com>
+
+
+Module Parameters
+-----------------
+
+* bus_speed (unsigned int)
+Allows changing of the bus speed.  Normally, the bus speed is set by the BIOS
+and never needs to be changed.  However, some SMBus analyzers are too slow for
+monitoring the bus during debug, thus the need for this module parameter.
+Specify the bus speed in kHz.
+Available bus frequency settings:
+  0  no change
+  80 kHz
+  100 kHz
+  400 kHz
+  1000 kHz
+
+
+Description
+-----------
+
+The S12xx series of SOCs have a pair of integrated SMBus 2.0 controllers
+targeted primarily at the microserver and storage markets.
+
+The S12xx series contain a pair of PCI functions.  An output of lspci will show
+something similar to the following:
+
+  00:13.0 System peripheral: Intel Corporation Centerton SMBus 2.0 Controller 0
+  00:13.1 System peripheral: Intel Corporation Centerton SMBus 2.0 Controller 1

drivers/i2c/busses/Kconfig

@@ -122,6 +122,16 @@ config I2C_ISCH
 	  This driver can also be built as a module. If so, the module
 	  will be called i2c-isch.
 
+config I2C_ISMT
+	tristate "Intel iSMT SMBus Controller"
+	depends on PCI && X86
+	help
+	  If you say yes to this option, support will be included for the Intel
+	  iSMT SMBus host controller interface.
+
+	  This driver can also be built as a module.  If so, the module will be
+	  called i2c-ismt.
+
 config I2C_PIIX4
 	tristate "Intel PIIX4 and compatible (ATI/AMD/Serverworks/Broadcom/SMSC)"
 	depends on PCI

drivers/i2c/busses/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_I2C_AMD756_S4882)	+= i2c-amd756-s4882.o
 obj-$(CONFIG_I2C_AMD8111)	+= i2c-amd8111.o
 obj-$(CONFIG_I2C_I801)		+= i2c-i801.o
 obj-$(CONFIG_I2C_ISCH)		+= i2c-isch.o
+obj-$(CONFIG_I2C_ISMT)		+= i2c-ismt.o
 obj-$(CONFIG_I2C_NFORCE2)	+= i2c-nforce2.o
 obj-$(CONFIG_I2C_NFORCE2_S4985)	+= i2c-nforce2-s4985.o
 obj-$(CONFIG_I2C_PIIX4)		+= i2c-piix4.o