hwmon: Add tc654 driver

Add support for the tc654 and tc655 fan controllers from Microchip.

http://ww1.microchip.com/downloads/en/DeviceDoc/20001734C.pdf

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Acked-by: Rob Herring <robh@kernel.org>
[groeck: Fixed continuation line alignments]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/i2c/trivial-devices.txt

@@ -121,6 +121,8 @@ microchip,mcp4662-502	Microchip 8-bit Dual I2C Digital Potentiometer with NV Mem
 microchip,mcp4662-103	Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (10k)
 microchip,mcp4662-503	Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (50k)
 microchip,mcp4662-104	Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (100k)
+microchip,tc654		PWM Fan Speed Controller With Fan Fault Detection
+microchip,tc655		PWM Fan Speed Controller With Fan Fault Detection
 national,lm63		Temperature sensor with integrated fan control
 national,lm75		I2C TEMP SENSOR
 national,lm80		Serial Interface ACPI-Compatible Microprocessor System Hardware Monitor

Documentation/hwmon/tc654

@@ -0,0 +1,31 @@
+Kernel driver tc654
+===================
+
+Supported chips:
+  * Microship TC654 and TC655
+    Prefix: 'tc654'
+    Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20001734C.pdf
+
+Authors:
+        Chris Packham <chris.packham@alliedtelesis.co.nz>
+        Masahiko Iwamoto <iwamoto@allied-telesis.co.jp>
+
+Description
+-----------
+This driver implements support for the Microchip TC654 and TC655.
+
+The TC654 uses the 2-wire interface compatible with the SMBUS 2.0
+specification. The TC654 has two (2) inputs for measuring fan RPM and
+one (1) PWM output which can be used for fan control.
+
+Configuration Notes
+-------------------
+Ordinarily the pwm1_mode ABI is used for controlling the pwm output
+mode.  However, for this chip the output is always pwm, and the
+pwm1_mode determines if the pwm output is controlled via the pwm1 value
+or via the Vin analog input.
+
+
+Setting pwm1_mode to 1 will cause the pwm output to be driven based on
+the pwm1 value. Setting pwm1_mode to 0 will cause the pwm output to be
+driven based on the Vin input.

drivers/hwmon/Kconfig

@@ -907,6 +907,17 @@ config SENSORS_MCP3021
 	  This driver can also be built as a module.  If so, the module
 	  will be called mcp3021.
 
+config SENSORS_TC654
+	tristate "Microchip TC654/TC655 and compatibles"
+	depends on I2C
+	help
+	  If you say yes here you get support for TC654 and TC655.
+	  The TC654 and TC655 are PWM mode fan speed controllers with
+	  FanSense technology for use with brushless DC fans.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called tc654.
+
 config SENSORS_MENF21BMC_HWMON
 	tristate "MEN 14F021P00 BMC Hardware Monitoring"
 	depends on MFD_MENF21BMC

drivers/hwmon/Makefile

@@ -122,6 +122,7 @@ obj-$(CONFIG_SENSORS_MAX6697)	+= max6697.o
 obj-$(CONFIG_SENSORS_MAX31790)	+= max31790.o
 obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
 obj-$(CONFIG_SENSORS_MCP3021)	+= mcp3021.o
+obj-$(CONFIG_SENSORS_TC654)	+= tc654.o
 obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
 obj-$(CONFIG_SENSORS_NCT6683)	+= nct6683.o
 obj-$(CONFIG_SENSORS_NCT6775)	+= nct6775.o