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authorTom Rini <trini@konsulko.com>2017-05-10 21:40:11 (GMT)
committerTom Rini <trini@konsulko.com>2017-05-10 21:40:11 (GMT)
commit1f5541c8818d3ecd243f9bbf58db9ea5f55a3195 (patch)
tree83053c0f224f8fe641550492e95818033e5af7e2 /doc
parent102d86552abc82818c22b39fdef4b3a280a60643 (diff)
parent2085de57f3928d72b27338f68d4250d1fb302d04 (diff)
downloadu-boot-fsl-qoriq-1f5541c8818d3ecd243f9bbf58db9ea5f55a3195.tar.xz
Merge git://git.denx.de/u-boot-rockchip
This adds a new firefly-rk3399 board, MIPI support for rk3399 and rk3288, rk818 pmic support, mkimage improvements for rockchip and a few other things.
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+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 ::= <single-pwm> [pwm-list]
+ single-pwm ::= <pwm-phandle> <pwm-specifier>
+ 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
+<dt-bindings/pwm/pwm.h>) 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>;
+ };