DT documentation for PWM controller added with updated compatible string. Signed-off-by: Wesley W. Terpstra <wes...@sifive.com> [Atish: Compatible string update] Signed-off-by: Atish Patra <atish.pa...@wdc.com> Signed-off-by: Yash Shah <yash.s...@sifive.com> --- .../devicetree/bindings/pwm/pwm-sifive.txt | 44 ++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sifive.txt
diff --git a/Documentation/devicetree/bindings/pwm/pwm-sifive.txt b/Documentation/devicetree/bindings/pwm/pwm-sifive.txt new file mode 100644 index 0000000..250d8ee --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/pwm-sifive.txt @@ -0,0 +1,44 @@ +SiFive PWM controller + +Unlike most other PWM controllers, the SiFive PWM controller currently only +supports one period for all channels in the PWM. This is set globally in DTS. +The period also has significant restrictions on the values it can achieve, +which the driver rounds to the nearest achievable frequency. + +Required properties: +- compatible: should be something similar to "sifive,<chip>-pwm" for + the PWM as integrated on a particular chip, and + "sifive,pwm<version>" for the general PWM IP block + programming model. Supported compatible strings are: + "sifive,fu540-c000-pwm" for the SiFive PWM v0 as + integrated onto the SiFive FU540 chip, and "sifive,pwm0" + for the SiFive PWM v0 IP block with no chip integration + tweaks. +- reg: physical base address and length of the controller's registers +- clocks: The frequency the controller runs at +- #pwm-cells: Should be 2. + The first cell is the PWM channel number + The second cell is the PWM polarity +- sifive,approx-period: the driver will get as close to this period as it can +- interrupts: one interrupt per PWM channel + +PWM RTL that corresponds to the IP block version numbers can be found +here: + +https://github.com/sifive/sifive-blocks/tree/master/src/main/scala/devices/pwm + +Further information on the format of the IP +block-specific version numbers can be found in +Documentation/devicetree/bindings/sifive/sifive-blocks-ip-versioning.txt + +Examples: + +pwm: pwm@10020000 { + compatible = "sifive,fu540-c000-pwm","sifive,pwm0"; + reg = <0x0 0x10020000 0x0 0x1000>; + clocks = <&tlclk>; + interrupt-parent = <&plic>; + interrupts = <42 43 44 45>; + #pwm-cells = <2>; + sifive,approx-period = <1000000>; +}; -- 1.9.1
