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author | Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de> | 2015-10-23 03:29:33 +0200 |
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committer | Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de> | 2015-10-23 03:29:33 +0200 |
commit | 15dfd0df63ce6847081d09b2bbd567cc0cc4eae1 (patch) | |
tree | 3b73f24fcef970bfcace3cbb297cfa57f3994682 /Documentation/devicetree/bindings/gpio/gpio.txt | |
parent | 328aa7a45af61bc0060c80847daa67fef7b9c0d0 (diff) | |
parent | 0149138c4142da287d23f9d5c6038f7fb5e30ac2 (diff) | |
download | kernel_samsung_smdk4412-15dfd0df63ce6847081d09b2bbd567cc0cc4eae1.zip kernel_samsung_smdk4412-15dfd0df63ce6847081d09b2bbd567cc0cc4eae1.tar.gz kernel_samsung_smdk4412-15dfd0df63ce6847081d09b2bbd567cc0cc4eae1.tar.bz2 |
initial merge with 3.2.72
Diffstat (limited to 'Documentation/devicetree/bindings/gpio/gpio.txt')
-rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio.txt | 46 |
1 files changed, 37 insertions, 9 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt index edaa84d..4e16ba4 100644 --- a/Documentation/devicetree/bindings/gpio/gpio.txt +++ b/Documentation/devicetree/bindings/gpio/gpio.txt @@ -4,17 +4,45 @@ Specifying GPIO information for devices 1) gpios property ----------------- -Nodes that makes use of GPIOs should define them using `gpios' property, -format of which is: <&gpio-controller1-phandle gpio1-specifier - &gpio-controller2-phandle gpio2-specifier - 0 /* holes are permitted, means no GPIO 3 */ - &gpio-controller4-phandle gpio4-specifier - ...>; +Nodes that makes use of GPIOs should specify them using one or more +properties, each containing a 'gpio-list': -Note that gpio-specifier length is controller dependent. + gpio-list ::= <single-gpio> [gpio-list] + single-gpio ::= <gpio-phandle> <gpio-specifier> + gpio-phandle : phandle to gpio controller node + gpio-specifier : Array of #gpio-cells specifying specific gpio + (controller specific) + +GPIO properties should be named "[<name>-]gpios". Exact +meaning of each gpios property must be documented in the device tree +binding for each device. + +For example, the following could be used to describe gpios pins to use +as chip select lines; with chip selects 0, 1 and 3 populated, and chip +select 2 left empty: + + gpio1: gpio1 { + gpio-controller + #gpio-cells = <2>; + }; + gpio2: gpio2 { + gpio-controller + #gpio-cells = <1>; + }; + [...] + chipsel-gpios = <&gpio1 12 0>, + <&gpio1 13 0>, + <0>, /* holes are permitted, means no GPIO 2 */ + <&gpio2 2>; + +Note that gpio-specifier length is controller dependent. In the +above example, &gpio1 uses 2 cells to specify a gpio, while &gpio2 +only uses one. gpio-specifier may encode: bank, pin position inside the bank, whether pin is open-drain and whether pin is logically inverted. +Exact meaning of each specifier cell is controller specific, and must +be documented in the device tree binding for the device. Example of the node using GPIOs: @@ -28,8 +56,8 @@ and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller. 2) gpio-controller nodes ------------------------ -Every GPIO controller node must have #gpio-cells property defined, -this information will be used to translate gpio-specifiers. +Every GPIO controller node must both an empty "gpio-controller" +property, and have #gpio-cells contain the size of the gpio-specifier. Example of two SOC GPIO banks defined as gpio-controller nodes: |