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authorIngo Molnar <mingo@kernel.org>2015-05-08 13:33:33 +0200
committerIngo Molnar <mingo@kernel.org>2015-05-08 13:33:33 +0200
commit7ae383be81781c5e1347f71c3eb0d53ce5188200 (patch)
treed2dfedb78cf4ee2bc9cc460af3be106b08e01050 /Documentation/acpi/enumeration.txt
parentx86: Force inlining of atomic ops (diff)
parentMerge tag 'pm+acpi-4.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/... (diff)
downloadlinux-7ae383be81781c5e1347f71c3eb0d53ce5188200.tar.xz
linux-7ae383be81781c5e1347f71c3eb0d53ce5188200.zip
Merge branch 'linus' into x86/asm, before applying dependent patch
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/acpi/enumeration.txt')
-rw-r--r--Documentation/acpi/enumeration.txt28
1 files changed, 24 insertions, 4 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
index 9b121a569ab4..15dfce708ebf 100644
--- a/Documentation/acpi/enumeration.txt
+++ b/Documentation/acpi/enumeration.txt
@@ -253,9 +253,14 @@ input driver:
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:
+and GpioInt. These resources can be used to pass GPIO numbers used by
+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