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Date: Mon, 7 Jun 2021 15:24:53 +0300 From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> To: Thierry Reding <thierry.reding@...il.com>, Uwe Kleine-König <u.kleine-koenig@...gutronix.de>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Flavio Suligoi <f.suligoi@...m.it>, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org, linux-acpi@...r.kernel.org Cc: Jonathan Corbet <corbet@....net>, Lee Jones <lee.jones@...aro.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Len Brown <lenb@...nel.org> Subject: [PATCH v3 1/6] 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@...ux.intel.com> --- 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
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