[PATCH v2] gpio-vx855: add device tree binding

[Daniel Drake]

This is needed to enable the HDD LED on the OLPC XO-1.5 laptop,
enabled through devicetree and the gpio-leds driver.

Signed-off-by: Daniel Drake <dsd@xxxxxxxxxx>
---
 .../devicetree/bindings/gpio/gpio_vx855.txt        |   20 ++++++++++++++++++++
 drivers/gpio/gpio-vx855.c                          |    5 +++++
 2 files changed, 25 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio_vx855.txt

v2: extended the documentation with information about the pin numbering
scheme, which matches that of the driver.

diff --git a/Documentation/devicetree/bindings/gpio/gpio_vx855.txt b/Documentation/devicetree/bindings/gpio/gpio_vx855.txt
new file mode 100644
index 0000000..17285a5
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio_vx855.txt
@@ -0,0 +1,20 @@
+VIA VX855 GPIO controller
+
+Required properties:
+- compatible : "via,vx855-gpio"
+- #gpio-cells : Should be two. The first cell is the pin number and the
+  second cell is used to specify optional parameters:
+  - bit 0 specifies polarity (0 for normal, 1 for inverted)
+- gpio-controller : Marks the device node as a GPIO controller.
+
+As VIA differentiates between GPI, GPO and GPIO on its 42 available pins,
+with each pin type restarting numbering at 0, the following numbering scheme
+is used in the device tree for the pin number:
+
+PIN NO		VIA NAME
+0..13		GPI 0..13
+14..26		GPO 0..12
+27..41		GPIO 0..14
+
+For example, GPIO 11 (VIA name) is referred to with pin number 38 in the
+device tree.
diff --git a/drivers/gpio/gpio-vx855.c b/drivers/gpio/gpio-vx855.c
index ef5aabd..5b7e9ba 100644
--- a/drivers/gpio/gpio-vx855.c
+++ b/drivers/gpio/gpio-vx855.c
@@ -31,6 +31,7 @@
 #include <linux/platform_device.h>
 #include <linux/pci.h>
 #include <linux/io.h>
+#include <linux/of.h>
 
 #define MODULE_NAME "vx855_gpio"
 
@@ -216,6 +217,10 @@ static void vx855gpio_gpio_setup(struct vx855_gpio *vg)
 	c->ngpio = NR_VX855_GP;
 	c->can_sleep = 0;
 	c->names = vx855gpio_names;
+
+#ifdef CONFIG_OF_GPIO
+	c->of_node = of_find_compatible_node(NULL, NULL, "via,vx855-gpio");
+#endif
 }
 
 /* This platform device is ordinarily registered by the vx855 mfd driver */
-- 
1.7.6

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