pwm: sti: Supply Device Tree binding documentation for ST's PWM IP

Signed-off-by: Ajit Pal Singh <ajitpal.singh@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/Documentation/devicetree/bindings/pwm/pwm-st.txt b/Documentation/devicetree/bindings/pwm/pwm-st.txt
new file mode 100644 (file)
index 0000000..84d2fb8
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+++ b/Documentation/devicetree/bindings/pwm/pwm-st.txt
@@ -0,0 +1,41 @@
+STMicroelectronics PWM driver bindings
+--------------------------------------
+
+Required parameters:
+- compatible :         "st,pwm"
+- #pwm-cells :                 Number of cells used to specify a PWM. First cell
+                       specifies the per-chip index of the PWM to use and the
+                       second cell is the period in nanoseconds - fixed to 2
+                       for STiH41x.
+- reg :                        Physical base address and length of the controller's
+                       registers.
+- pinctrl-names:       Set to "default".
+- pinctrl-0:           List of phandles pointing to pin configuration nodes
+                       for PWM module.
+                       For Pinctrl properties, please refer to [1].
+- clock-names:                 Set to "pwm".
+- clocks:              phandle of the clock used by the PWM module.
+                       For Clk properties, please refer to [2].
+
+Optional properties:
+- st,pwm-num-chan:     Number of available channels. If not passed, the driver
+                       will consider single channel by default.
+
+[1] Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+[2] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Example:
+
+pwm1: pwm@fe510000 {
+       compatible = "st,pwm";
+       reg = <0xfe510000 0x68>;
+       #pwm-cells = <2>;
+       pinctrl-names = "default";
+       pinctrl-0 = <&pinctrl_pwm1_chan0_default
+                    &pinctrl_pwm1_chan1_default
+                    &pinctrl_pwm1_chan2_default
+                    &pinctrl_pwm1_chan3_default>;
+       clocks = <&clk_sysin>;
+       clock-names = "pwm";
+       st,pwm-num-chan = <4>;
+};