Hammer Button Driver

UserSpace Access
the carrier board push button can be accessed via the sysfs interface as well as a shell script functionality. the sysfs entry for the push button can be found in the directory mark /sys/devices/platform/gpio-keys.0. the driver also looks for a shell script in /sbin called pb0.sh. this shell script can be used to start user land applications. here is the provided example shell script:


 * 1) !/bin/sh

if [ $1 = "down" ] ; then if [ -x /mnt/flash/scripts/pb0.down ] ; then /mnt/flash/scripts/pb0.down else current=`cat /sys/class/leds/led1/brightness` if [ "${current}" = 0 ] ; then echo 1 > /sys/class/leds/led1/brightness else echo 0 > /sys/class/leds/led1/brightness fi   fi else if [ -x /mnt/flash/scripts/pb0.up ] ; then /mnt/flash/scripts/pb0.up   fi fi#

Adding New PushButtons
the gpio buttons are defined in the linux-2.6.xx/arch/arm/mach-s3c2410/mach-tct_hammer.c file. each button requires that the gpio be defined, a name, and key scan code associated with it. in addition standard platform data and platform device have to be defined.

static struct gpio_keys_button gpio_keys_buttons[] = { [0] = {           .code	    = 0x26, .gpio          = S3C2410_GPG3, .active_low    = 0, .desc          = "PB0", }, };

static struct gpio_keys_platform_data gpio_keys_data = { .buttons  = gpio_keys_buttons, .nbuttons  = ARRAY_SIZE(gpio_keys_buttons), }; static struct platform_device tct_hammer_buttons = { .name		= "gpio-keys", .id		= 0, .dev		= { .platform_data = &gpio_keys_data, }, };