From 00ce25c6dcdae5582ae4be37147ab33678adc995 Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Fri, 25 Apr 2014 11:22:32 +0200 Subject: Add devicetree source files as of Linux-3.15-rc2 This adds the Linux dts files to barebox. The dts files are generated from Ian Campbells device-tree-rebasing.git: git://xenbits.xen.org/people/ianc/device-tree-rebasing.git The dts are found in dts/ in the barebox repository and will be updated from upstream regularly, probably for each upstream -rc. To keep the synchronization with upstream easy no changes to the original files are allowed under dts/. Instead changes to upstream dts files will be done using overlays in arch/$ARCH/dts/. Signed-off-by: Sascha Hauer --- dts/Bindings/pwm/pwm.txt | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 dts/Bindings/pwm/pwm.txt (limited to 'dts/Bindings/pwm/pwm.txt') diff --git a/dts/Bindings/pwm/pwm.txt b/dts/Bindings/pwm/pwm.txt new file mode 100644 index 0000000000..8556263b85 --- /dev/null +++ b/dts/Bindings/pwm/pwm.txt @@ -0,0 +1,69 @@ +Specifying PWM information for devices +====================================== + +1) PWM user nodes +----------------- + +PWM users should specify a list of PWM devices that they want to use +with a property containing a 'pwm-list': + + pwm-list ::= [pwm-list] + single-pwm ::= + pwm-phandle : phandle to PWM controller node + pwm-specifier : array of #pwm-cells specifying the given PWM + (controller specific) + +PWM properties should be named "pwms". The exact meaning of each pwms +property must be documented in the device tree binding for each device. +An optional property "pwm-names" may contain a list of strings to label +each of the PWM devices listed in the "pwms" property. If no "pwm-names" +property is given, the name of the user node will be used as fallback. + +Drivers for devices that use more than a single PWM device can use the +"pwm-names" property to map the name of the PWM device requested by the +pwm_get() call to an index into the list given by the "pwms" property. + +The following example could be used to describe a PWM-based backlight +device: + + pwm: pwm { + #pwm-cells = <2>; + }; + + [...] + + bl: backlight { + pwms = <&pwm 0 5000000>; + pwm-names = "backlight"; + }; + +Note that in the example above, specifying the "pwm-names" is redundant +because the name "backlight" would be used as fallback anyway. + +pwm-specifier typically encodes the chip-relative PWM number and the PWM +period in nanoseconds. + +Optionally, the pwm-specifier can encode a number of flags (defined in +) in a third cell: +- PWM_POLARITY_INVERTED: invert the PWM signal polarity + +Example with optional PWM specifier for inverse polarity + + bl: backlight { + pwms = <&pwm 0 5000000 PWM_POLARITY_INVERTED>; + pwm-names = "backlight"; + }; + +2) PWM controller nodes +----------------------- + +PWM controller nodes must specify the number of cells used for the +specifier using the '#pwm-cells' property. + +An example PWM controller might look like this: + + pwm: pwm@7000a000 { + compatible = "nvidia,tegra20-pwm"; + reg = <0x7000a000 0x100>; + #pwm-cells = <2>; + }; -- cgit v1.2.3