Reggie's gpio-keys driver

reggie-gpio-keys.c

// Reggie added, simple gpio keys polled driver, adds button support via gpio
// will be useful for embedded devices, see gpio-mouse, gpio-fan and rotary-encoder
// for other examples of gpio access to devices from the linux kernel
// this will use GPIO4,17,21,22 as a simple test, they will be set to active_low
// so should have a pullup added to each pin and button tied to ground.
// We have to use polled at the moment because the current kernel doesn't have
// code to handle an interrupt driven gpio-keys driver, which would've been much nicer
// you should check the wiki to make sure that these gpio are correctly configured
// and see whether they are physically pulled up on the schematic, if they're not
// add a 10k pullup to the gpio-keys pins and tie the button to gnd
// buttons are set active low, so closing the switch should pull them to ground
// and press the button
 
#if defined(CONFIG_KEYBOARD_GPIO_POLLED)|| defined(CONFIG_KEYBOARD_GPIO_MODULE)
#include <linux/gpio_keys.h>
#include <linux/input.h>
#define BCM2708_KEYS_DEBOUNCE 5
 
static struct gpio_keys_button bcm2708_gpio_keys_table[] = {
 
        {
                .type           = EV_KEY,
                .code           = KEY_ENTER,
                .gpio           = 4,
                .active_low     = 1,
                .desc           = "gpio-keys: enter",
                .debounce_interval      = BCM2708_KEYS_DEBOUNCE,
        }, {
                .type           = EV_KEY,
                .code           = KEY_A,
                .gpio           = 17,
                .active_low     = 1,
                .desc           = "gpio-keys: A",
                .debounce_interval      = BCM2708_KEYS_DEBOUNCE,
        }, {
                .type           = EV_KEY,
                .code           = KEY_B,
                .gpio           = 21,
                .active_low     = 1,
                .desc           = "gpio-keys: B",
                .debounce_interval      = BCM2708_KEYS_DEBOUNCE,
        }, {
                .type           = EV_KEY,
                .code           = KEY_C,
                .gpio           = 22,
                .active_low     = 1,
                .desc           = "gpio-keys: C",
                .debounce_interval      = BCM2708_KEYS_DEBOUNCE,
        },
};
 
static struct gpio_keys_platform_data bcm2708_gpio_keys_data = {
        .buttons        = bcm2708_gpio_keys_table,
        .nbuttons       = ARRAY_SIZE(bcm2708_gpio_keys_table),
        .poll_interval  = 20
};
 
static struct platform_device bcm2708_device_gpio_keys = {
        .name           = "gpio-keys-polled",
        .dev            = {
                           .platform_data = &bcm2708_gpio_keys_data,
},
};
 
 
static void __init bcm2708_init_gpio_keys(void)
{
        platform_device_register(&bcm2708_device_gpio_keys);
}
#else
static inline void bcm2708_init_gpio_keys(void)
{
}