最近需要使用到power button按键，linux中有gpio keys的机制，只要注册即可。
device注册
arch/arm/mach-mx6/board-mx6q_sabresd.c
#define SABRESD_POWER_OFF IMX_GPIO_NR(3, 29)
static struct gpio_keys_button new_sabresd_buttons[] = {
GPIO_BUTTON(SABRESD_VOLUME_UP, KEY_VOLUMEUP, 1, "volume-up", 0, 1),
GPIO_BUTTON(SABRESD_VOLUME_DN, KEY_VOLUMEDOWN, 1, "volume-down", 0, 1),
GPIO_BUTTON(SABRESD_POWER_OFF, KEY_POWER, 1, "power-key", 1, 1),
};
static struct gpio_keys_platform_data new_sabresd_button_data = {
.buttons = new_sabresd_buttons,
.nbuttons = ARRAY_SIZE(new_sabresd_buttons),
};
static struct platform_device sabresd_button_device = {
.name = "gpio-keys",
.id = -1,
.num_resources = 0,
};
static void __init imx6q_add_device_buttons(void)
{
/* fix me */
/* For new sabresd(RevB4 ane above) change the
* ONOFF key(SW1) design, the SW1 now connect
* to GPIO_3_29, it can be use as a general power
* key that Android reuired. But those old sabresd
* such as RevB or older could not support this
* change, so it needs a way to distinguish different
* boards. Before board id/rev are defined cleary,
* there is a simple way to achive this, that is using
* SOC revison to identify differnt board revison.
*
* With the new sabresd change and SW mapping the
* SW1 as power key, below function related to power
* key are OK on new sabresd board(B4 or above).
* 1 Act as power button to power on the device when device is power off
* 2 Act as power button to power on the device(need keep press SW1 >5s)
* 3 Act as power key to let device suspend/resume
* 4 Act screenshort(hold power key and volume down key for 2s)
*/
platform_device_add_data(&sabresd_button_device,
&new_sabresd_button_data,
sizeof(new_sabresd_button_data));
platform_device_register(&sabresd_button_device);
}
static void __init mx6_sabresd_board_init(void)
{
......
imx6q_add_device_buttons();
......
}
driver
对应驱动代码
drivers/input/keyboard/gpio_keys.c
test
加载驱动之后，按住power key，却不能熄灭屏幕。由于是linux系统，与安卓有所不同，这一块的问题还没解决。
目前只是在文件系统层，使系统进入低功耗模式，power key就能够唤醒系统。不过这样每次都得手动操作才能使屏幕熄灭。
echo mem > /sys/power/state
echo standby > /sys/power/state
root@freescale /sys/power$ ll
-rw-r--r-- 1 root root 4096 Jan 1 00:15 device_suspend_time_threshold
-rw-r--r-- 1 root root 4096 Jan 1 00:15 pm_async
-rw-r--r-- 1 root root 4096 Jan 1 00:15 pm_test
-rw-r--r-- 1 root root 4096 Jan 1 00:15 state
-rw-r--r-- 1 root root 4096 Jan 1 00:15 wakeup_count
# 查看支持的模式
root@freescale /sys/power$ cat state
standby mem
# 使cpu进入standby模式 (或者mem模式), 此时屏幕熄灭
root@freescale /sys/power$ echo standby > state
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.01 seconds) done.
Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
Suspending console(s) (use no_console_suspend to debug)
# 按住power key，屏幕又重新点亮
add wake up source irq 103
PM: suspend of devices complete after 3.163 msecs
PM: suspend devices took 0.010 seconds
PM: late suspend of devices complete after 0.701 msecs
Disabling non-boot CPUs ...
CPU1: shutdown
Suspended for 0.000 seconds
Enabling non-boot CPUs ...
CPU1: Booted secondary processor
Calibrating delay loop (skipped) already calibrated this CPU
i.MXC CPU frequency driver
CPU1 is up
PM: early resume of devices complete after 0.497 msecs
imx-ipuv3 imx-ipuv3.0: IPU DMFC NORMAL mode: 1(0~1), 5B(4,5), 5F(6,7)
remove wake up source irq 103
usb 2-1: reset high speed USB device number 2 using fsl-ehci
usb 2-1.1: reset low speed USB device number 3 using fsl-ehci
PM: resume of devices complete after 1357.464 msecs
PM: resume devices took 1.360 seconds
Restarting tasks ... done.
Tony Liu
2016-12-3, Shenzhen