Add support for GMT G762/G763 PWM fan controllers

GMT G762/763 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 chip. Introduced driver
provides various knobs to control the operations of the chip (via
sysfs interface). Specific characteristics of the system can be passed
either using board init code or via DT. Documentation for both the
driver and DT bindings are also provided.

Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Tested-by: Simon Guinot <simon.guinot@sequanux.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 47 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/hwmon/g762.txt b/Documentation/devicetree/bindings/hwmon/g762.txt
new file mode 100644
index 00000000000..25cc6d8ee57
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/g762.txt
@@ -0,0 +1,47 @@
+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 */
+   };