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| author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2015-03-17 13:40:12 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-03-18 04:02:35 +0300 |
| commit | 56b858dfad9b97aea88f9fe87b1468ddaf154c94 (patch) | |
| tree | c4919642d14b34370eae96187253f0cd814fed18 /Documentation | |
| parent | 06e5801b8cb3fc057d88cb4dc03c0b64b2744cda (diff) | |
| download | linux-56b858dfad9b97aea88f9fe87b1468ddaf154c94.tar.xz | |
ACPI: Update GPIO documentation to mention _DSD
Make sure that the ACPI enumeration.txt provides latest information on how
to describe and retrieve GPIOs now that we can take advantage of _DSD
device properties.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/acpi/enumeration.txt | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt index 9b121a569ab4..750401f91341 100644 --- a/Documentation/acpi/enumeration.txt +++ b/Documentation/acpi/enumeration.txt @@ -254,8 +254,13 @@ GPIO support ~~~~~~~~~~~~ ACPI 5 introduced two new resources to describe GPIO connections: GpioIo and GpioInt. These resources are used be used to pass GPIO numbers used by -the device to the driver. For example: +the device to the driver. ACPI 5.1 extended this with _DSD (Device +Specific Data) which made it possible to name the GPIOs among other things. +For example: + +Device (DEV) +{ Method (_CRS, 0, NotSerialized) { Name (SBUF, ResourceTemplate() @@ -285,6 +290,18 @@ the device to the driver. For example: Return (SBUF) } + // ACPI 5.1 _DSD used for naming the GPIOs + Name (_DSD, Package () + { + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), + Package () + { + Package () {"power-gpios", Package() {^DEV, 0, 0, 0 }}, + Package () {"irq-gpios", Package() {^DEV, 1, 0, 0 }}, + } + }) + ... + These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0" specifies the path to the controller. In order to use these GPIOs in Linux we need to translate them to the corresponding Linux GPIO descriptors. @@ -300,11 +317,11 @@ a code like this: struct gpio_desc *irq_desc, *power_desc; - irq_desc = gpiod_get_index(dev, NULL, 1); + irq_desc = gpiod_get(dev, "irq"); if (IS_ERR(irq_desc)) /* handle error */ - power_desc = gpiod_get_index(dev, NULL, 0); + power_desc = gpiod_get(dev, "power"); if (IS_ERR(power_desc)) /* handle error */ @@ -313,6 +330,9 @@ a code like this: There are also devm_* versions of these functions which release the descriptors once the device is released. +See Documentation/acpi/gpio-properties.txt for more information about the +_DSD binding related to GPIOs. + MFD devices ~~~~~~~~~~~ The MFD devices register their children as platform devices. For the child |