Input: add generic GPIO-tilt driver

There exist tilt switches that simply report their tilt-state via
some gpios. The number and orientation of their axes can vary
depending on the switch used and the build of the device. Also two
or more one-axis switches could be combined to provide multi-dimensional
orientation.

One example of a device using such a switch is the family of Qisda
ebook readers, where the switch provides information about the
landscape / portrait orientation of the device. The example in
Documentation/input/gpio-tilt.txt documents exactly this one-axis
device.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 73 insertions, 0 deletions

diff --git a/include/linux/input/gpio_tilt.h b/include/linux/input/gpio_tilt.h
new file mode 100644
index 00000000000..c1cc52d380e
--- /dev/null
+++ b/include/linux/input/gpio_tilt.h
@@ -0,0 +1,73 @@
+#ifndef _INPUT_GPIO_TILT_H
+#define _INPUT_GPIO_TILT_H
+
+/**
+ * struct gpio_tilt_axis - Axis used by the tilt switch
+ * @axis:               Constant describing the axis, e.g. ABS_X
+ * @min:                minimum value for abs_param
+ * @max:                maximum value for abs_param
+ * @fuzz:               fuzz value for abs_param
+ * @flat:               flat value for abs_param
+ */
+struct gpio_tilt_axis {
+        int axis;
+        int min;
+        int max;
+        int fuzz;
+        int flat;
+};
+
+/**
+ * struct gpio_tilt_state - state description
+ * @gpios:              bitfield of gpio target-states for the value
+ * @axes:               array containing the axes settings for the gpio state
+ *                      The array indizes must correspond to the axes defined
+ *                      in platform_data
+ *
+ * This structure describes a supported axis settings
+ * and the necessary gpio-state which represent it.
+ *
+ * The n-th bit in the bitfield describes the state of the n-th GPIO
+ * from the gpios-array defined in gpio_regulator_config below.
+ */
+struct gpio_tilt_state {
+        int gpios;
+        int *axes;
+};
+
+/**
+ * struct gpio_tilt_platform_data
+ * @gpios:              Array containing the gpios determining the tilt state
+ * @nr_gpios:           Number of gpios
+ * @axes:               Array of gpio_tilt_axis descriptions
+ * @nr_axes:            Number of axes
+ * @states:             Array of gpio_tilt_state entries describing
+ *                      the gpio state for specific tilts
+ * @nr_states:          Number of states available
+ * @debounce_interval:  debounce ticks interval in msecs
+ * @poll_interval:      polling interval in msecs - for polling driver only
+ * @enable:             callback to enable the tilt switch
+ * @disable:            callback to disable the tilt switch
+ *
+ * This structure contains gpio-tilt-switch configuration
+ * information that must be passed by platform code to the
+ * gpio-tilt input driver.
+ */
+struct gpio_tilt_platform_data {
+        struct gpio *gpios;
+        int nr_gpios;
+
+        struct gpio_tilt_axis *axes;
+        int nr_axes;
+
+        struct gpio_tilt_state *states;
+        int nr_states;
+
+        int debounce_interval;
+
+        unsigned int poll_interval;
+        int (*enable)(struct device *dev);
+        void (*disable)(struct device *dev);
+};
+
+#endif