On Tue, Dec 18, 2018 at 2:46 AM Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> wrote: > > On Fri, Dec 14, 2018 at 11:50:41AM +0530, Yash Shah wrote: > > DT documentation for PWM controller added with updated compatible > > string. > > > > Signed-off-by: Wesley W. Terpstra <wesley@xxxxxxxxxx> > > [Atish: Compatible string update] > > Signed-off-by: Atish Patra <atish.patra@xxxxxxx> > > Signed-off-by: Yash Shah <yash.shah@xxxxxxxxxx> > > --- > > .../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 > > This is unusual and the example below lists a clock phandle (which is > the common thing), so I guess the description is just wrong. You are right, I will correct the description. > > > +- #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 > > What is the unit? I'd drop "approx", that the driver might not be able > to exactly hit the specified period is (IMHO) obvious and doesn't need > to be mentioned in the property name. The unit is nanoseconds. Will add the unit suffix to the property name. > > > +- 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>; > > +}; > > Best regards > Uwe Thanks for the comments! > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | http://www.pengutronix.de/ |
