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| author | Grant Likely <grant.likely@secretlab.ca> | 2011-06-03 11:07:16 -0600 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2011-06-28 15:35:53 -0600 |
| commit | bf859f84a19f8e562af4a990a287b5e3edabc572 (patch) | |
| tree | c458e053f099fa3cd0cc3a298a60e0891826c8cc /Documentation/devicetree | |
| parent | 33300571b1111264fd0c5701733f7576323f3e35 (diff) | |
| download | linux-3.10-bf859f84a19f8e562af4a990a287b5e3edabc572.tar.gz linux-3.10-bf859f84a19f8e562af4a990a287b5e3edabc572.tar.bz2 linux-3.10-bf859f84a19f8e562af4a990a287b5e3edabc572.zip | |
gpio/dt: Refine GPIO device tree binding
Allow for multiple named gpio properties
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'Documentation/devicetree')
| -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 edaa84d288a..4e16ba4feab 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: |