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| author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2015-04-01 10:13:16 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2015-04-04 15:20:27 +0200 |
| commit | cfc507648c2c9060aeba0d1a41bb5e5985f16636 (patch) | |
| tree | f09c07f83670cc7e9604a7c2a9baf8913f34faaa /Documentation/gpio/board.txt | |
| parent | docs/completion.txt: Various tweaks and corrections (diff) | |
| download | linux-cfc507648c2c9060aeba0d1a41bb5e5985f16636.tar.xz linux-cfc507648c2c9060aeba0d1a41bb5e5985f16636.zip | |
Documentation: gpio: Update ACPI part of the document to mention _DSD
With ACPI 5.1 _DSD (Device Specific Data) it is now possible to name
functions just like Device Tree is doing. Make sure that the documentation
mentions _DSD as the recommended way to describe GPIOs in ACPI systems.
Reported-by: Darren Hart <dvhart@linux.intel.com>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/gpio/board.txt')
| -rw-r--r-- | Documentation/gpio/board.txt | 41 |
1 files changed, 37 insertions, 4 deletions
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 ------------- |