hwmon: Add driver for SMSC EMC2103 temperature monitor and fan controller

SMSC's EMC2103 family of temperature/fan controllers have 1
onboard and up to 3 external temperature sensors, and allow
closed-loop control of one fan.  This patch adds support for
them.
Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

Documentation/hwmon/emc2103

+Kernel driver emc2103
+======================
+
+Supported chips:
+  * SMSC EMC2103
+    Addresses scanned: I2C 0x2e
+    Prefix: 'emc2103'
+    Datasheet: Not public
+
+Authors:
+        Steve Glendinning <steve.glendinning@smsc.com>
+
+Description
+-----------
+
+The Standard Microsystems Corporation (SMSC) EMC2103 chips
+contain up to 4 temperature sensors and a single fan controller.
+
+Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
+triggered if the rotation speed has dropped below a programmable limit. Fan
+readings can be divided by a programmable divider (1, 2, 4 or 8) to give
+the readings more range or accuracy. Not all RPM values can accurately be
+represented, so some rounding is done. With a divider of 1, the lowest
+representable value is 480 RPM.
+
+This driver supports RPM based control, to use this a fan target
+should be written to fan1_target and pwm1_enable should be set to 3.
+
+The 2103-2 and 2103-4 variants have a third temperature sensor, which can
+be connected to two anti-parallel diodes.  These values can be read
+as temp3 and temp4.  If only one diode is attached to this channel, temp4
+will show as "fault".  The module parameter "apd=0" can be used to suppress
+this 4th channel when anti-parallel diodes are not fitted.

MAINTAINERS

@@ -5279,6 +5279,13 @@ S:	Maintained
 F:	Documentation/hwmon/smm665
 F:	drivers/hwmon/smm665.c
 
+SMSC EMC2103 HARDWARE MONITOR DRIVER
+M:	Steve Glendinning <steve.glendinning@smsc.com>
+L:	lm-sensors@lm-sensors.org
+S:	Supported
+F:	Documentation/hwmon/emc2103
+F:	drivers/hwmon/emc2103.c
+
 SMSC47B397 HARDWARE MONITOR DRIVER
 M:	"Mark M. Hoffman" <mhoffman@lightlink.com>
 L:	lm-sensors@lm-sensors.org

drivers/hwmon/Kconfig

@@ -804,6 +804,16 @@ config SENSORS_EMC1403
 	  Threshold values can be configured using sysfs.
 	  Data from the different diodes are accessible via sysfs.
 
+config SENSORS_EMC2103
+	tristate "SMSC EMC2103"
+	depends on I2C
+	help
+	  If you say yes here you get support for the temperature
+	  and fan sensors of the SMSC EMC2103 chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called emc2103.
+
 config SENSORS_SMSC47M1
 	tristate "SMSC LPC47M10x and compatibles"
 	help

drivers/hwmon/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_SENSORS_PKGTEMP)	+= pkgtemp.o
 obj-$(CONFIG_SENSORS_DME1737)	+= dme1737.o
 obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
 obj-$(CONFIG_SENSORS_EMC1403)	+= emc1403.o
+obj-$(CONFIG_SENSORS_EMC2103)	+= emc2103.o
 obj-$(CONFIG_SENSORS_F71805F)	+= f71805f.o
 obj-$(CONFIG_SENSORS_F71882FG)	+= f71882fg.o
 obj-$(CONFIG_SENSORS_F75375S)	+= f75375s.o