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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>
103 lines
2.5 KiB
Text
103 lines
2.5 KiB
Text
Driver for tilt-switches connected via GPIOs
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============================================
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Generic driver to read data from tilt switches connected via gpios.
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Orientation can be provided by one or more than one tilt switches,
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i.e. each tilt switch providing one axis, and the number of axes
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is also not limited.
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Data structures:
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----------------
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The array of struct gpio in the gpios field is used to list the gpios
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that represent the current tilt state.
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The array of struct gpio_tilt_axis describes the axes that are reported
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to the input system. The values set therein are used for the
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input_set_abs_params calls needed to init the axes.
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The array of struct gpio_tilt_state maps gpio states to the corresponding
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values to report. The gpio state is represented as a bitfield where the
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bit-index corresponds to the index of the gpio in the struct gpio array.
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In the same manner the values stored in the axes array correspond to
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the elements of the gpio_tilt_axis-array.
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Example:
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--------
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Example configuration for a single TS1003 tilt switch that rotates around
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one axis in 4 steps and emitts the current tilt via two GPIOs.
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static int sg060_tilt_enable(struct device *dev) {
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/* code to enable the sensors */
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};
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static void sg060_tilt_disable(struct device *dev) {
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/* code to disable the sensors */
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};
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static struct gpio sg060_tilt_gpios[] = {
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{ SG060_TILT_GPIO_SENSOR1, GPIOF_IN, "tilt_sensor1" },
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{ SG060_TILT_GPIO_SENSOR2, GPIOF_IN, "tilt_sensor2" },
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};
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static struct gpio_tilt_state sg060_tilt_states[] = {
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{
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.gpios = (0 << 1) | (0 << 0),
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.axes = (int[]) {
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0,
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},
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}, {
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.gpios = (0 << 1) | (1 << 0),
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.axes = (int[]) {
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1, /* 90 degrees */
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},
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}, {
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.gpios = (1 << 1) | (1 << 0),
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.axes = (int[]) {
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2, /* 180 degrees */
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},
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}, {
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.gpios = (1 << 1) | (0 << 0),
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.axes = (int[]) {
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3, /* 270 degrees */
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},
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},
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};
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static struct gpio_tilt_axis sg060_tilt_axes[] = {
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{
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.axis = ABS_RY,
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.min = 0,
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.max = 3,
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.fuzz = 0,
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.flat = 0,
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},
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};
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static struct gpio_tilt_platform_data sg060_tilt_pdata= {
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.gpios = sg060_tilt_gpios,
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.nr_gpios = ARRAY_SIZE(sg060_tilt_gpios),
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.axes = sg060_tilt_axes,
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.nr_axes = ARRAY_SIZE(sg060_tilt_axes),
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.states = sg060_tilt_states,
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.nr_states = ARRAY_SIZE(sg060_tilt_states),
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.debounce_interval = 100,
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.poll_interval = 1000,
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.enable = sg060_tilt_enable,
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.disable = sg060_tilt_disable,
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};
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static struct platform_device sg060_device_tilt = {
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.name = "gpio-tilt-polled",
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.id = -1,
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.dev = {
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.platform_data = &sg060_tilt_pdata,
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},
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};
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