hwmon: Add LTC4245 driver

Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot
Swap controller I2C monitoring interface.
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

Documentation/hwmon/ltc4245

+Kernel driver ltc4245
+=====================
+
+Supported chips:
+  * Linear Technology LTC4245
+    Prefix: 'ltc4245'
+    Addresses scanned: 0x20-0x3f
+    Datasheet:
+        http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
+
+Author: Ira W. Snyder <iws@ovro.caltech.edu>
+
+
+Description
+-----------
+
+The LTC4245 controller allows a board to be safely inserted and removed
+from a live backplane in multiple supply systems such as CompactPCI and
+PCI Express.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for LTC4245 devices, due to the fact that some
+of the possible addresses are unfriendly to probing. You will need to use
+the "force" parameter to tell the driver where to find the device.
+
+Example: the following will load the driver for an LTC4245 at address 0x23
+on I2C bus #1:
+$ modprobe ltc4245 force=1,0x23
+
+
+Sysfs entries
+-------------
+
+The LTC4245 has built-in limits for over and under current warnings. This
+makes it very likely that the reference circuit will be used.
+
+This driver uses the values in the datasheet to change the register values
+into the values specified in the sysfs-interface document. The current readings
+rely on the sense resistors listed in Table 2: "Sense Resistor Values".
+
+in1_input		12v input voltage (mV)
+in2_input		5v  input voltage (mV)
+in3_input		3v  input voltage (mV)
+in4_input		Vee (-12v) input voltage (mV)
+
+in1_min_alarm		12v input undervoltage alarm
+in2_min_alarm		5v  input undervoltage alarm
+in3_min_alarm		3v  input undervoltage alarm
+in4_min_alarm		Vee (-12v) input undervoltage alarm
+
+curr1_input		12v current (mA)
+curr2_input		5v  current (mA)
+curr3_input		3v  current (mA)
+curr4_input		Vee (-12v) current (mA)
+
+curr1_max_alarm		12v overcurrent alarm
+curr2_max_alarm		5v  overcurrent alarm
+curr3_max_alarm		3v  overcurrent alarm
+curr4_max_alarm		Vee (-12v) overcurrent alarm
+
+in5_input		12v output voltage (mV)
+in6_input		5v  output voltage (mV)
+in7_input		3v  output voltage (mV)
+in8_input		Vee (-12v) output voltage (mV)
+
+in5_min_alarm		12v output undervoltage alarm
+in6_min_alarm		5v  output undervoltage alarm
+in7_min_alarm		3v  output undervoltage alarm
+in8_min_alarm		Vee (-12v) output undervoltage alarm
+
+in9_input		GPIO #1 voltage data
+in10_input		GPIO #2 voltage data
+in11_input		GPIO #3 voltage data
+
+power1_input		12v power usage (mW)
+power2_input		5v  power usage (mW)
+power3_input		3v  power usage (mW)
+power4_input		Vee (-12v) power usage (mW)

drivers/hwmon/Kconfig

@@ -549,6 +549,17 @@ config SENSORS_LM93
 	  This driver can also be built as a module.  If so, the module
 	  will be called lm93.
 
+config SENSORS_LTC4245
+	tristate "Linear Technology LTC4245"
+	depends on I2C && EXPERIMENTAL
+	default n
+	help
+	  If you say yes here you get support for Linear Technology LTC4245
+	  Multiple Supply Hot Swap Controller I2C interface.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc4245.
+
 config SENSORS_MAX1111
 	tristate "Maxim MAX1111 Multichannel, Serial 8-bit ADC chip"
 	depends on SPI_MASTER

drivers/hwmon/Makefile

@@ -62,6 +62,7 @@ obj-$(CONFIG_SENSORS_LM87)	+= lm87.o
 obj-$(CONFIG_SENSORS_LM90)	+= lm90.o
 obj-$(CONFIG_SENSORS_LM92)	+= lm92.o
 obj-$(CONFIG_SENSORS_LM93)	+= lm93.o
+obj-$(CONFIG_SENSORS_LTC4245)	+= ltc4245.o
 obj-$(CONFIG_SENSORS_MAX1111)	+= max1111.o
 obj-$(CONFIG_SENSORS_MAX1619)	+= max1619.o
 obj-$(CONFIG_SENSORS_MAX6650)	+= max6650.o