GPIO_PGUP
peup = bus_space_read_4(iot, gpioh, GPIO_PGUP);
bus_space_write_4(iot, gpioh, GPIO_PGUP, peup);
data = bus_space_read_4(iot, gpio_ioh, GPIO_PGUP);
bus_space_write_4(iot, gpio_ioh, GPIO_PGUP, data | (1<<4));
reg = bus_space_read_2(iot, gpioh, GPIO_PGUP);
bus_space_write_2(iot, gpioh, GPIO_PGUP, reg & ~(1<<5));
IOW(S3C2410_GPIO_BASE+GPIO_PGUP, 0xffff);