[v6,2/2] gpio: Document GPIO hogging mechanism
diff mbox

Message ID 1422899085-678-3-git-send-email-bparrot@ti.com
State New
Headers show

Commit Message

Benoit Parrot Feb. 2, 2015, 5:44 p.m. UTC
Add GPIO hogging documentation to gpio.txt

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
---
 Documentation/devicetree/bindings/gpio/gpio.txt | 30 +++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

Comments

Linus Walleij March 4, 2015, 10:11 a.m. UTC | #1
On Mon, Feb 2, 2015 at 6:44 PM, Benoit Parrot <bparrot@ti.com> wrote:

> Add GPIO hogging documentation to gpio.txt
>
> Signed-off-by: Benoit Parrot <bparrot@ti.com>
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>

Patch applied.

Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch
diff mbox

diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index b9bd1d6..a0ce2bd 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -115,6 +115,29 @@  Every GPIO controller node must contain both an empty "gpio-controller"
 property, and a #gpio-cells integer property, which indicates the number of
 cells in a gpio-specifier.
 
+The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
+providing automatic GPIO request and configuration as part of the
+gpio-controller's driver probe function.
+
+Each GPIO hog definition is represented as a child node of the GPIO controller.
+Required properties:
+- gpio-hog:   A property specifying that this child node represent a GPIO hog.
+- gpios:      Store the GPIO information (id, flags, ...). Shall contain the
+	      number of cells specified in its parent node (GPIO controller
+	      node).
+Only one of the following properties scanned in the order shown below.
+This means that when multiple properties are present they will be searched
+in the order presented below and the first match is taken as the intended
+configuration.
+- input:      A property specifying to set the GPIO direction as input.
+- output-low  A property specifying to set the GPIO direction as output with
+	      the value low.
+- output-high A property specifying to set the GPIO direction as output with
+	      the value high.
+
+Optional properties:
+- line-name:  The GPIO label name. If not present the node name is used.
+
 Example of two SOC GPIO banks defined as gpio-controller nodes:
 
 	qe_pio_a: gpio-controller@1400 {
@@ -122,6 +145,13 @@  Example of two SOC GPIO banks defined as gpio-controller nodes:
 		reg = <0x1400 0x18>;
 		gpio-controller;
 		#gpio-cells = <2>;
+
+		line_b {
+			gpio-hog;
+			gpios = <6 0>;
+			output-low;
+			line-name = "foo-bar-gpio";
+		};
 	};
 
 	qe_pio_e: gpio-controller@1460 {