From ef3d13b867637f9a791b524100362ba7e2b69810 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Mon, 7 Jun 2021 15:24:53 +0300 Subject: docs: firmware-guide: ACPI: Add a PWM example 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 Acked-by: Rafael J. Wysocki Signed-off-by: Thierry Reding --- Documentation/firmware-guide/acpi/enumeration.rst | 32 +++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'Documentation/firmware-guide') 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", // + 0, // + 600000000, // + 0, // + } + } + } + + }) + ... + +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 ============ -- cgit v1.2.3