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authorIlpo Järvinen <ilpo.jarvinen@linux.intel.com>2022-04-26 15:24:42 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-04-26 14:48:21 +0200
commit1e70d57e7285996bcf0a226eac8c5ba43a89f85d (patch)
treed102b02791372763da5a11f7c13fbba154641e17 /Documentation/firmware-guide
parent103dcf2ea2df2669d3e4496974e6bb0911ff515f (diff)
ACPI / property: Document RS485 _DSD properties
Document RS485 related properties returned from ACPI _DSD as device properties. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220426122448.38997-5-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/firmware-guide')
-rw-r--r--Documentation/firmware-guide/acpi/enumeration.rst25
1 files changed, 25 insertions, 0 deletions
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
===========