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authorHeiko Stübner <heiko@sntech.de>2011-11-29 11:04:09 -0800
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2011-11-30 23:41:16 -0800
commit3bfd5c5baf66e975b0f365a0cda8d75bf2953ebe (patch)
tree49517da40dd6071ed9d3acde9fa1ef97d39ede13 /Documentation/input
parenta6c61789c8499381a5fe612f11dc95d0b55e590a (diff)
downloadlinux-3bfd5c5baf66e975b0f365a0cda8d75bf2953ebe.tar.gz
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>
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diff --git a/Documentation/input/gpio-tilt.txt b/Documentation/input/gpio-tilt.txt
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+Driver for tilt-switches connected via GPIOs
+============================================
+
+Generic driver to read data from tilt switches connected via gpios.
+Orientation can be provided by one or more than one tilt switches,
+i.e. each tilt switch providing one axis, and the number of axes
+is also not limited.
+
+
+Data structures:
+----------------
+
+The array of struct gpio in the gpios field is used to list the gpios
+that represent the current tilt state.
+
+The array of struct gpio_tilt_axis describes the axes that are reported
+to the input system. The values set therein are used for the
+input_set_abs_params calls needed to init the axes.
+
+The array of struct gpio_tilt_state maps gpio states to the corresponding
+values to report. The gpio state is represented as a bitfield where the
+bit-index corresponds to the index of the gpio in the struct gpio array.
+In the same manner the values stored in the axes array correspond to
+the elements of the gpio_tilt_axis-array.
+
+
+Example:
+--------
+
+Example configuration for a single TS1003 tilt switch that rotates around
+one axis in 4 steps and emitts the current tilt via two GPIOs.
+
+static int sg060_tilt_enable(struct device *dev) {
+ /* code to enable the sensors */
+};
+
+static void sg060_tilt_disable(struct device *dev) {
+ /* code to disable the sensors */
+};
+
+static struct gpio sg060_tilt_gpios[] = {
+ { SG060_TILT_GPIO_SENSOR1, GPIOF_IN, "tilt_sensor1" },
+ { SG060_TILT_GPIO_SENSOR2, GPIOF_IN, "tilt_sensor2" },
+};
+
+static struct gpio_tilt_state sg060_tilt_states[] = {
+ {
+ .gpios = (0 << 1) | (0 << 0),
+ .axes = (int[]) {
+ 0,
+ },
+ }, {
+ .gpios = (0 << 1) | (1 << 0),
+ .axes = (int[]) {
+ 1, /* 90 degrees */
+ },
+ }, {
+ .gpios = (1 << 1) | (1 << 0),
+ .axes = (int[]) {
+ 2, /* 180 degrees */
+ },
+ }, {
+ .gpios = (1 << 1) | (0 << 0),
+ .axes = (int[]) {
+ 3, /* 270 degrees */
+ },
+ },
+};
+
+static struct gpio_tilt_axis sg060_tilt_axes[] = {
+ {
+ .axis = ABS_RY,
+ .min = 0,
+ .max = 3,
+ .fuzz = 0,
+ .flat = 0,
+ },
+};
+
+static struct gpio_tilt_platform_data sg060_tilt_pdata= {
+ .gpios = sg060_tilt_gpios,
+ .nr_gpios = ARRAY_SIZE(sg060_tilt_gpios),
+
+ .axes = sg060_tilt_axes,
+ .nr_axes = ARRAY_SIZE(sg060_tilt_axes),
+
+ .states = sg060_tilt_states,
+ .nr_states = ARRAY_SIZE(sg060_tilt_states),
+
+ .debounce_interval = 100,
+
+ .poll_interval = 1000,
+ .enable = sg060_tilt_enable,
+ .disable = sg060_tilt_disable,
+};
+
+static struct platform_device sg060_device_tilt = {
+ .name = "gpio-tilt-polled",
+ .id = -1,
+ .dev = {
+ .platform_data = &sg060_tilt_pdata,
+ },
+};