[PATCH v5 04/10] ACPI / property: Document RS485 _DSD properties

From: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
To: linux-serial@vger.kernel.org, Greg KH <gregkh@linuxfoundation.org>
Cc: "Jiri Slaby" <jirislaby@kernel.org>,
	"Lukas Wunner" <lukas@wunner.de>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Vicente Bergas" <vicencb@gmail.com>,
	"Johan Hovold" <johan@kernel.org>,
	heiko@sntech.de, giulio.benetti@micronovasrl.com,
	"Heikki Krogerus" <heikki.krogerus@linux.intel.com>,
	"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
Subject: [PATCH v5 04/10] ACPI / property: Document RS485 _DSD properties
Date: Tue, 26 Apr 2022 15:24:42 +0300	[thread overview]
Message-ID: <20220426122448.38997-5-ilpo.jarvinen@linux.intel.com> (raw)
In-Reply-To: <20220426122448.38997-1-ilpo.jarvinen@linux.intel.com>

Document RS485 related properties returned from ACPI _DSD as device
properties.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 .../firmware-guide/acpi/enumeration.rst       | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst
index 47fb4d6d4557..f584a6a0c5e3 100644
--- a/Documentation/firmware-guide/acpi/enumeration.rst
+++ b/Documentation/firmware-guide/acpi/enumeration.rst
@@ -390,6 +390,31 @@ descriptors once the device is released.
 See Documentation/firmware-guide/acpi/gpio-properties.rst for more information
 about the _DSD binding related to GPIOs.
 
+RS-485 support
+==============
+
+ACPI _DSD (Device Specific Data) can be used to describe RS-485 capability
+of UART.
+
+For example::
+
+	Device (DEV)
+	{
+		...
+
+		// ACPI 5.1 _DSD used for RS-485 capabilities
+		Name (_DSD, Package ()
+		{
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package ()
+			{
+				Package () {"rs485-rts-active-low", Zero},
+				Package () {"rs485-rx-active-high", Zero},
+				Package () {"rs485-rx-during-tx", Zero},
+			}
+		})
+		...
+
 MFD devices
 ===========
 
-- 
2.30.2

