[PATCH 4/4] Documentation: Add device tree bindings for Freescale FTM PWM
From: Thierry Reding <hidden>
Date: 2013-08-23 09:23:52
Also in:
linux-pwm, lkml
On Wed, Aug 21, 2013 at 11:07:42AM +0800, Xiubo Li wrote:
Signed-off-by: Xiubo Li <redacted> --- .../devicetree/bindings/pwm/fsl-ftm-pwm.txt | 52 ++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt
It used to be that device tree bindings documentation was squashed into the same commit as the driver. I see some point in splitting this up given that this will eventually go into a completely separate tree, but I just want to make sure this is now the official way of splitting patches so I can tell that to people in good conscience.
quoted hunk ↗ jump to hunk
diff --git a/Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt b/Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt new file mode 100644 index 0000000..698965b --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt@@ -0,0 +1,52 @@ +Freescale FTM PWM controller + +Required properties: +- compatible: should be "fsl,vf610-ftm-pwm" +- reg: physical base address and length of the controller's registers +- #pwm-cells: Should be 3. Number of cells being used to specify PWM property. + First cell specifies the per-chip channel index of the PWM to use, the + second cell is the period in nanoseconds and bit 0 in the third cell is + used to encode the polarity of PWM output. Set bit 0 of the third in PWM + specifier to 1 for inverse polarity & set to 0 for normal polarity. +- fsl,pwm-clk-ps: the ftm0 pwm clock's prescaler, divide-by 2^n(n = 0 ~ 7). +- fsl,pwm-cpwm: Center-Aligned PWM (CPWM) mode. +- fsl,pwm-number: the number of PWM devices, and is must equal to the number + of "fsl,pwm-channels". +- fsl,pwm-channels: the channels' order which is be used for pwm in ftm0 + module, and they must be one or some of 0 ~ 7, because the ftm0 only has + 8 channels can be used. +- for very channel, the revlatived the pinctrl should be at least two state + {"enN", "dsN"}, which "en" means "enable", "ds" means "disable" and "N" + means the order of the channel.
This is missing a description of the clocks and clock-names properties.
+
+Example:
+
+pwm0: pwm at 40038000 {
+ compatible = "fsl,vf610-ftm-pwm";
+ reg = <0x40038000 0x1000>;
+ #pwm-cells = <3>;
+ pinctrl-names = "en0", "ds0", "en3", "ds3";
+ pinctrl-0 = <&pinctrl_pwm0_ch0_en>;
+ pinctrl-1 = <&pinctrl_pwm0_ch0_ds>;
+ pinctrl-2 = <&pinctrl_pwm0_ch3_en>;
+ pinctrl-3 = <&pinctrl_pwm0_ch3_ds>;
+ fsl,pwm-clk-ps = <7>;
+ fsl,pwm-cpwm = <0>;
+ fsl,pwm-number = <2>;
+ fsl,pwm-channels = <0 3>;
+ ...And this mixes tabs and spaces for indentation.
+ };
+
+leds {
+ compatible = "pwm-leds";
+ led {
+ label = "fsl_led";
+ pwms = <&pwm0 0 10000000 0>;
+ max-brightness = <127>;
+ };
+ backlight {
+ label = "fsl_backlight";
+ pwms = <&pwm0 3 10000000 1>;
+ max-brightness = <100>;
+ };I don't think I like this at all. This example suggests to use the pwm-leds driver for backlight control. Why not use pwm-backlight instead? Thierry -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 836 bytes Desc: not available URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20130823/033cb054/attachment.sig>