diff options
Diffstat (limited to 'Documentation/devicetree/bindings/gpio/gpio.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio.txt | 46 |
1 files changed, 9 insertions, 37 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt index 4e16ba4feab..edaa84d288a 100644 --- a/Documentation/devicetree/bindings/gpio/gpio.txt +++ b/Documentation/devicetree/bindings/gpio/gpio.txt @@ -4,45 +4,17 @@ Specifying GPIO information for devices 1) gpios property ----------------- -Nodes that makes use of GPIOs should specify them using one or more -properties, each containing a 'gpio-list': +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 + ...>; - 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. +Note that gpio-specifier length is controller dependent. 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: @@ -56,8 +28,8 @@ and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller. 2) gpio-controller nodes ------------------------ -Every GPIO controller node must both an empty "gpio-controller" -property, and have #gpio-cells contain the size of the gpio-specifier. +Every GPIO controller node must have #gpio-cells property defined, +this information will be used to translate gpio-specifiers. Example of two SOC GPIO banks defined as gpio-controller nodes: |