hwmon: Add devicetree bindings to gpio-fan

Allow a gpio-fan to be defined in devicetree, see binding documentation
for details.

Signed-off-by: Jamie Lentin <jm@lentin.co.uk>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

1 files changed, 25 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/gpio/gpio-fan.txt b/Documentation/devicetree/bindings/gpio/gpio-fan.txt
new file mode 100644
index 000000000000..2dd457a3469a
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-fan.txt
@@ -0,0 +1,25 @@
+Bindings for fan connected to GPIO lines
+
+Required properties:
+- compatible : "gpio-fan"
+- gpios: Specifies the pins that map to bits in the control value,
+  ordered MSB-->LSB.
+- gpio-fan,speed-map: A mapping of possible fan RPM speeds and the
+  control value that should be set to achieve them. This array
+  must have the RPM values in ascending order.
+
+Optional properties:
+- alarm-gpios: This pin going active indicates something is wrong with
+  the fan, and a udev event will be fired.
+
+Examples:
+
+        gpio_fan {
+                compatible = "gpio-fan";
+                gpios = <&gpio1 14 1
+                         &gpio1 13 1>;
+                gpio-fan,speed-map = <0    0
+                                      3000 1
+                                      6000 2>;
+                alarm-gpios = <&gpio1 15 1>;
+        };