X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=Documentation%2Fgpio%2Fboard.txt;h=b80606de545ad809fb147688060b26b51af4d5e1;hb=5e6c94a999f67f120c6bbba71bbee840dfee6338;hp=8b35f51fe7b6a3e8d11a2abc3104913794349cce;hpb=05f6d02521d4c7a656c5135d6d81c345ce531ac0;p=firefly-linux-kernel-4.4.55.git

diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt
index 8b35f51fe7b6..b80606de545a 100644
--- a/Documentation/gpio/board.txt
+++ b/Documentation/gpio/board.txt
@@ -50,10 +50,43 @@ gpiod_is_active_low(power) will be true).
 
 ACPI
 ----
-ACPI does not support function names for GPIOs. Therefore, only the "idx"
-argument of gpiod_get_index() is useful to discriminate between GPIOs assigned
-to a device. The "con_id" argument can still be set for debugging purposes (it
-will appear under error messages as well as debug and sysfs nodes).
+ACPI also supports function names for GPIOs in a similar fashion to DT.
+The above DT example can be converted to an equivalent ACPI description
+with the help of _DSD (Device Specific Data), introduced in ACPI 5.1:
+
+	Device (FOO) {
+		Name (_CRS, ResourceTemplate () {
+			GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
+				"\\_SB.GPI0") {15} // red
+			GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
+				"\\_SB.GPI0") {16} // green
+			GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
+				"\\_SB.GPI0") {17} // blue
+			GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
+				"\\_SB.GPI0") {1} // power
+		})
+
+		Name (_DSD, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () {
+					"led-gpios",
+					Package () {
+						^FOO, 0, 0, 1,
+						^FOO, 1, 0, 1,
+						^FOO, 2, 0, 1,
+					}
+				},
+				Package () {
+					"power-gpios",
+					Package () {^FOO, 3, 0, 0},
+				},
+			}
+		})
+	}
+
+For more information about the ACPI GPIO bindings see
+Documentation/acpi/gpio-properties.txt.
 
 Platform Data
 -------------