GPIO keys
From ArmadeusWiki
How to use gpio-keys driver to read states of the user switch of your Armadeus board (APF51)
Introduction
Your APF51 board features a user switch connected to a GPIO pin (GPIO1_3). The driver gpio-keys translates GPIO events in key/button events.
Test
# cat /dev/input/event0
Then you should see weirds characters when pressing the user button of the apf51_dev board:
T ����T �T � ��T %�
- if the test wiped out your console, you can get it back with:
# reset
You also can use the tool evtest.
Hardware handling ---> [*] input-tools [*] evtest
# evtest /dev/input/event0 ... Event: time 1335981358.550329, type 22 (EV_PWR), code 0 (), value 1 Event: time 1335981358.550330, -------------- SYN_REPORT ------------ Event: time 1335981358.550329, type 22 (EV_PWR), code 0 (), value 0 Event: time 1335981358.550330, -------------- SYN_REPORT ------------
For APF27
First, you need to enable the gpio_keys in your kernel.
Device Drivers ---> Input device support ---> <*> Event interface [*] Keyboards ---> <*> GPIO Buttons
Then, in your apf27-dev.c, you need to define your GPIO button before the variable platform_devices[] and also include gpio_keys.h and input.h.
#include <linux/gpio_keys.h>
#include <linux/input.h>
/* GPIO KEYS */
#if 1
/* PORTA_6 used as gpio_keys (GPIO used as input event) */
static struct gpio_keys_button apf27_gpio_keys[] = {
{
.code = EV_PWR, /* See include/linux/input.h for more event code */
.gpio = (GPIO_PORTA | 6), /* GPIO number */
.active_low = 0,
.desc = "Notification when the AC is deconnected", /* Button description*/
.type = 0, /* See include/linux/input.h for more type code */
},
};
static struct gpio_keys_platform_data apf27_gpio_keys_data = {
.buttons = apf27_gpio_keys,
.nbuttons = ARRAY_SIZE(apf27_gpio_keys),
};
static struct platform_device apf27_gpio_keys_device = {
.name = "gpio-keys",
.id = 0,
.dev = {
.platform_data = &apf27_gpio_keys_data,
},
};
# define GPIO_KEYS &apf27_gpio_keys_device,
#else
# define GPIO_KEYS
#endif
Add the button to get it recognized by the card.
static struct platform_device *platform_devices[] __initdata = {
ALSA_SOUND
GPIO_KEYS
};