root/include/linux/spi/ads7846.h

/* linux/spi/ads7846.h */

/* Touchscreen characteristics vary between boards and models.  The
 * platform_data for the device's "struct device" holds this information.
 *
 * It's OK if the min/max values are zero.
 */
enum ads7846_filter {
        ADS7846_FILTER_OK,
        ADS7846_FILTER_REPEAT,
        ADS7846_FILTER_IGNORE,
};

struct ads7846_platform_data {
        u16     model;                  /* 7843, 7845, 7846. */
        u16     vref_delay_usecs;       /* 0 for external vref; etc */
        u16     vref_mv;                /* external vref value, milliVolts */
        bool    keep_vref_on;           /* set to keep vref on for differential
                                         * measurements as well */

        /* Settling time of the analog signals; a function of Vcc and the
         * capacitance on the X/Y drivers.  If set to non-zero, two samples
         * are taken with settle_delay us apart, and the second one is used.
         * ~150 uSec with 0.01uF caps.
         */
        u16     settle_delay_usecs;

        /* If set to non-zero, after samples are taken this delay is applied
         * and penirq is rechecked, to help avoid false events.  This value
         * is affected by the material used to build the touch layer.
         */
        u16     penirq_recheck_delay_usecs;

        u16     x_plate_ohms;
        u16     y_plate_ohms;

        u16     x_min, x_max;
        u16     y_min, y_max;
        u16     pressure_min, pressure_max;

        u16     debounce_max;           /* max number of additional readings
                                         * per sample */
        u16     debounce_tol;           /* tolerance used for filtering */
        u16     debounce_rep;           /* additional consecutive good readings
                                         * required after the first two */
        int     gpio_pendown;           /* the GPIO used to decide the pendown
                                         * state if get_pendown_state == NULL
                                         */
        int     (*get_pendown_state)(void);
        int     (*filter_init)  (struct ads7846_platform_data *pdata,
                                 void **filter_data);
        int     (*filter)       (void *filter_data, int data_idx, int *val);
        void    (*filter_cleanup)(void *filter_data);
};