Document RS485 related properties returned from ACPI _DSD as device
properties.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
.../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
