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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-14 14:05:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-14 14:05:05 -0800
commit980f3c344ff1cb4a8be9a169c6bde2dc74ca6288 (patch)
treef7b22006dec2cebed697b0a2c6701ca16c58c7a2 /Documentation/devicetree/bindings/gpio/gpio.txt
parentMerge git://git.kvack.org/~bcrl/aio-next (diff)
parentgpio: mcp23s08: fix up compilation error (diff)
downloadlinux-dev-980f3c344ff1cb4a8be9a169c6bde2dc74ca6288.tar.xz
linux-dev-980f3c344ff1cb4a8be9a169c6bde2dc74ca6288.zip
Merge tag 'gpio-v3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio
Pull take two of the GPIO updates: "Same stuff as last time, now with a fixup patch for the previous compile error plus I ran a few extra rounds of compile-testing. This is the bulk of GPIO changes for the v3.19 series: - A new API that allows setting more than one GPIO at the time. This is implemented for the new descriptor-based API only and makes it possible to e.g. toggle a clock and data line at the same time, if the hardware can do this with a single register write. Both consumers and drivers need new calls, and the core will fall back to driving individual lines where needed. Implemented for the MPC8xxx driver initially - Patched the mdio-mux-gpio and the serial mctrl driver that drives modems to use the new multiple-setting API to set several signals simultaneously - Get rid of the global GPIO descriptor array, and instead allocate descriptors dynamically for each GPIO on a certain GPIO chip. This moves us closer to getting rid of the limitation of using the global, static GPIO numberspace - New driver and device tree bindings for 74xx ICs - New driver and device tree bindings for the VF610 Vybrid - Support the RCAR r8a7793 and r8a7794 - Guidelines for GPIO device tree bindings trying to get things a bit more strict with the advent of combined device properties - Suspend/resume support for the MVEBU driver - A slew of minor fixes and improvements" * tag 'gpio-v3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (33 commits) gpio: mcp23s08: fix up compilation error gpio: pl061: document gpio-ranges property for bindings file gpio: pl061: hook request if gpio-ranges avaiable gpio: mcp23s08: Add option to configure IRQ output polarity as active high gpio: fix deferred probe detection for legacy API serial: mctrl_gpio: use gpiod_set_array function mdio-mux-gpio: Use GPIO descriptor interface and new gpiod_set_array function gpio: remove const modifier from gpiod_get_direction() gpio: remove gpio_descs global array gpio: mxs: implement get_direction callback gpio: em: Use dynamic allocation of GPIOs gpio: Check if base is positive before calling gpio_is_valid() gpio: mcp23s08: Add simple IRQ support for SPI devices gpio: mcp23s08: request a shared interrupt gpio: mcp23s08: Do not free unrequested interrupt gpio: rcar: Add r8a7793 and r8a7794 support gpio-mpc8xxx: add mpc8xxx_gpio_set_multiple function gpiolib: allow simultaneous setting of multiple GPIO outputs gpio: mvebu: add suspend/resume support gpio: gpio-davinci: remove duplicate check on resource ..
Diffstat (limited to 'Documentation/devicetree/bindings/gpio/gpio.txt')
-rw-r--r--Documentation/devicetree/bindings/gpio/gpio.txt40
1 files changed, 26 insertions, 14 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 3fb8f53071b8..b9bd1d64cfa6 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -13,13 +13,22 @@ properties, each containing a 'gpio-list':
gpio-specifier : Array of #gpio-cells specifying specific gpio
(controller specific)
-GPIO properties should be named "[<name>-]gpios". The exact
-meaning of each gpios property must be documented in the device tree
-binding for each device.
+GPIO properties should be named "[<name>-]gpios", with <name> being the purpose
+of this GPIO for the device. While a non-existent <name> is considered valid
+for compatibility reasons (resolving to the "gpios" property), it is not allowed
+for new bindings.
-For example, the following could be used to describe GPIO pins used
-as chip select lines; with chip selects 0, 1 and 3 populated, and chip
-select 2 left empty:
+GPIO properties can contain one or more GPIO phandles, but only in exceptional
+cases should they contain more than one. If your device uses several GPIOs with
+distinct functions, reference each of them under its own property, giving it a
+meaningful name. The only case where an array of GPIOs is accepted is when
+several GPIOs serve the same function (e.g. a parallel data line).
+
+The exact purpose of each gpios property must be documented in the device tree
+binding of the device.
+
+The following example could be used to describe GPIO pins used as device enable
+and bit-banged data signals:
gpio1: gpio1 {
gpio-controller
@@ -30,10 +39,12 @@ select 2 left empty:
#gpio-cells = <1>;
};
[...]
- chipsel-gpios = <&gpio1 12 0>,
- <&gpio1 13 0>,
- <0>, /* holes are permitted, means no GPIO 2 */
- <&gpio2 2>;
+
+ enable-gpios = <&gpio2 2>;
+ data-gpios = <&gpio1 12 0>,
+ <&gpio1 13 0>,
+ <&gpio1 14 0>,
+ <&gpio1 15 0>;
Note that gpio-specifier length is controller dependent. In the
above example, &gpio1 uses 2 cells to specify a gpio, while &gpio2
@@ -42,16 +53,17 @@ 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.
+be documented in the device tree binding for the device. Use the macros
+defined in include/dt-bindings/gpio/gpio.h whenever possible:
Example of a node using GPIOs:
node {
- gpios = <&qe_pio_e 18 0>;
+ enable-gpios = <&qe_pio_e 18 GPIO_ACTIVE_HIGH>;
};
-In this example gpio-specifier is "18 0" and encodes GPIO pin number,
-and GPIO flags as accepted by the "qe_pio_e" gpio-controller.
+GPIO_ACTIVE_HIGH is 0, so in this example gpio-specifier is "18 0" and encodes
+GPIO pin number, and GPIO flags as accepted by the "qe_pio_e" gpio-controller.
1.1) GPIO specifier best practices
----------------------------------