From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: "Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Flavio Suligoi" <f.suligoi@asem.it>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Thierry Reding" <thierry.reding@gmail.com>,
linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pwm@vger.kernel.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>, Lee Jones <lee.jones@linaro.org>
Subject: [PATCH v1 1/5] docs: firmware-guide: ACPI: Add a PWM example
Date: Mon, 31 May 2021 18:43:47 +0300 [thread overview]
Message-ID: <20210531154351.53614-1-andriy.shevchenko@linux.intel.com> (raw)
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>
---
.../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..0813508b45b0 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>
+ 600000, // <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 us (note that
+value is given in nanoseconds).
+
GPIO support
============
--
2.30.2
next reply other threads:[~2021-05-31 17:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-31 15:43 Andy Shevchenko [this message]
2021-05-31 15:43 ` [PATCH v1 2/5] pwm: core: Always require PWM flags to be provided Andy Shevchenko
2021-05-31 15:43 ` [PATCH v1 3/5] pwm: core: Convert to use fwnode for matching Andy Shevchenko
2021-05-31 15:43 ` [PATCH v1 4/5] pwm: core: Reuse fwnode_to_pwmchip() in ACPI case Andy Shevchenko
2021-05-31 15:43 ` [PATCH v1 5/5] pwm: core: Unify fwnode checks in the module Andy Shevchenko
2021-05-31 16:09 ` [PATCH v1 1/5] docs: firmware-guide: ACPI: Add a PWM example Andy Shevchenko
2021-05-31 19:41 ` Andy Shevchenko
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