diff options
Diffstat (limited to 'Documentation/input')
-rw-r--r-- | Documentation/input/gpio-tilt.txt | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/Documentation/input/gpio-tilt.txt b/Documentation/input/gpio-tilt.txt new file mode 100644 index 000000000000..06d60c3ff5e7 --- /dev/null +++ b/Documentation/input/gpio-tilt.txt @@ -0,0 +1,103 @@ +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, + }, +}; |