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| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2021-06-07 15:24:53 +0300 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2021-06-30 19:12:19 +0200 |
| commit | ef3d13b867637f9a791b524100362ba7e2b69810 (patch) | |
| tree | 6e42bc4617f7d0308c8ce74ebba7f43d569aa4b9 /Documentation/firmware-guide | |
| parent | 9939648a53c4c795bdac0d54df22423f81ccf5f0 (diff) | |
| download | linux-ef3d13b867637f9a791b524100362ba7e2b69810.tar.bz2 | |
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 <andriy.shevchenko@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'Documentation/firmware-guide')
| -rw-r--r-- | Documentation/firmware-guide/acpi/enumeration.rst | 32 |
1 files changed, 32 insertions, 0 deletions
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 ============ |