Add support for GMT G762/G763 PWM fan controllers

GMT G762/G763 PWM Fan controller

Required node properties:

 - "compatible": must be either "gmt,g762" or "gmt,g763"

 - "reg": I2C bus address of the device

 - "clocks": a fixed clock providing input clock frequency

	     on CLK pin of the chip.

Optional properties:

 - "fan_startv": fan startup voltage. Accepted values are 0, 1, 2 and 3.

	       The higher the more.

 - "pwm_polarity": pwm polarity. Accepted values are 0 (positive duty)

	       and 1 (negative duty).

 - "fan_gear_mode": fan gear mode. Supported values are 0, 1 and 2.

If an optional property is not set in .dts file, then current value is kept

unmodified (e.g. u-boot installed value).

Additional information on operational parameters for the device is available

in Documentation/hwmon/g762. A detailed datasheet for the device is available

at http://natisbad.org/NAS/refs/GMT_EDS-762_763-080710-0.2.pdf.

Example g762 node:

   clocks {

	#address-cells = <1>;

	#size-cells = <0>;

	g762_clk: fixedclk {

		 compatible = "fixed-clock";

		 #clock-cells = <0>;

		 clock-frequency = <8192>;

	}

   }

   g762: g762@3e {

	compatible = "gmt,g762";

	reg = <0x3e>;

	clocks = <&g762_clk>

	fan_gear_mode = <0>; /* chip default */

	fan_startv = <1>;    /* chip default */

	pwm_polarity = <0>;  /* chip default */

   };

Kernel driver g762

==================

The GMT G762 Fan Speed PWM Controller is connected directly to a fan

and performs closed-loop or open-loop control of the fan speed. Two

modes - PWM or DC - are supported by the device.

For additional information, a detailed datasheet is available at

http://natisbad.org/NAS/ref/GMT_EDS-762_763-080710-0.2.pdf. sysfs

bindings are described in Documentation/hwmon/sysfs-interface.

The following entries are available to the user in a subdirectory of

/sys/bus/i2c/drivers/g762/ to control the operation of the device.

This can be done manually using the following entries but is usually

done via a userland daemon like fancontrol.

Note that those entries do not provide ways to setup the specific

hardware characteristics of the system (reference clock, pulses per

fan revolution, ...); Those can be modified via devicetree bindings

documented in Documentation/devicetree/bindings/hwmon/g762.txt or

using a specific platform_data structure in board initialization

file (see include/linux/platform_data/g762.h).

  fan1_target: set desired fan speed. This only makes sense in closed-loop

            fan speed control (i.e. when pwm1_enable is set to 2).

  fan1_input: provide current fan rotation value in RPM as reported by

            the fan to the device.

  fan1_div: fan clock divisor. Supported value are 1, 2, 4 and 8.

  fan1_pulses: number of pulses per fan revolution. Supported values

            are 2 and 4.

  fan1_fault: reports fan failure, i.e. no transition on fan gear pin for

            about 0.7s (if the fan is not voluntarily set off).

  fan1_alarm: in closed-loop control mode, if fan RPM value is 25% out

            of the programmed value for over 6 seconds 'fan1_alarm' is

            set to 1.

  pwm1_enable: set current fan speed control mode i.e. 1 for manual fan

            speed control (open-loop) via pwm1 described below, 2 for

            automatic fan speed control (closed-loop) via fan1_target

            above.

  pwm1_mode: set or get fan driving mode: 1 for PWM mode, 0 for DC mode.

  pwm1: get or set PWM fan control value in open-loop mode. This is an

            integer value between 0 and 255. 0 stops the fan, 255 makes

            it run at full speed.

Both in PWM mode ('pwm1_mode' set to 1) and DC mode ('pwm1_mode' set to 0),

when current fan speed control mode is open-loop ('pwm1_enable' set to 1),

the fan speed is programmed by setting a value between 0 and 255 via 'pwm1'

entry (0 stops the fan, 255 makes it run at full speed). In closed-loop mode

('pwm1_enable' set to 2), the expected rotation speed in RPM can be passed to

the chip via 'fan1_target'. In closed-loop mode, the target speed is compared

with current speed (available via 'fan1_input') by the device and a feedback

is performed to match that target value. The fan speed value is computed

based on the parameters associated with the physical characteristics of the

system: a reference clock source frequency, a number of pulses per fan

revolution, etc.

Note that the driver will update its values at most once per second.

	  This driver can also be built as a module.  If so, the module

	  This driver can also be built as a module.  If so, the module

	  will be called g760a.

	  will be called g760a.

config SENSORS_G762

	tristate "GMT G762 and G763"

	depends on I2C

	help

	  If you say yes here you get support for Global Mixed-mode

	  Technology Inc G762 and G763 fan speed PWM controller chips.

	  This driver can also be built as a module.  If so, the module

	  will be called g762.

config SENSORS_GL518SM

config SENSORS_GL518SM

	tristate "Genesys Logic GL518SM"

	tristate "Genesys Logic GL518SM"

	depends on I2C

	depends on I2C

obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o

obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o

obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o

obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o

obj-$(CONFIG_SENSORS_G760A)	+= g760a.o

obj-$(CONFIG_SENSORS_G760A)	+= g760a.o

obj-$(CONFIG_SENSORS_G762)	+= g762.o

obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o

obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o

obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o

obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o

obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o

obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o