On Mon, Jun 7, 2021 at 2:24 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> When PWM support for ACPI has been added into the kernel, it missed
> the documentation update. Hence update documentation here.
>
> Fixes: 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
and I'm assuming this to go in via PWM.
> ---
> v3: despite flags being optional, don't alter it in the documentation
> v2: updated example to use 600 ms instead of 600 us (looks saner)
> .../firmware-guide/acpi/enumeration.rst | 32 +++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst
> index 9f0d5c854fa4..f588663ba906 100644
> --- a/Documentation/firmware-guide/acpi/enumeration.rst
> +++ b/Documentation/firmware-guide/acpi/enumeration.rst
> @@ -258,6 +258,38 @@ input driver::
> .id_table = mpu3050_ids,
> };
>
> +Reference to PWM device
> +=======================
> +
> +Sometimes a device can be a consumer of PWM channel. Obviously OS would like
> +to know which one. To provide this mapping the special property has been
> +introduced, i.e.::
> +
> + Device (DEV)
> + {
> + Name (_DSD, Package ()
> + {
> + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> + Package () {
> + Package () { "compatible", Package () { "pwm-leds" } },
> + Package () { "label", "alarm-led" },
> + Package () { "pwms",
> + Package () {
> + "\\_SB.PCI0.PWM", // <PWM device reference>
> + 0, // <PWM index>
> + 600000000, // <PWM period>
> + 0, // <PWM flags>
> + }
> + }
> + }
> +
> + })
> + ...
> +
> +In the above example the PWM-based LED driver references to the PWM channel 0
> +of \_SB.PCI0.PWM device with initial period setting equal to 600 ms (note that
> +value is given in nanoseconds).
> +
> GPIO support
> ============
>
> --
> 2.30.2
>
