The kernel resumes from the suspend mode when a wake-up event occurs. The following wake-up sources can be used:
- UART
- If enabled as a wake-up source, a UART input will trigger the kernel to resume
from the suspend mode.
- Required Kernel Configurations
- Same as Suspend
- Example Code
- To set RTC to wake up the APU after 10
seconds:
$ echo enabled > /sys/devices/platform/amba/ff000000.serial/tty/ttyAMA0/power/wakeup
- RTC
- If enabled as a wake-up source, the kernel will resume from the suspend mode
when the RTC timer expires. Note that the RTC wake-up source is enabled by default.
- Required Kernel Configurations
- Same as Suspend
- Example Code
- To wake up the APU on UART
input:
$ echo enabled > /sys/devices/platform/amba/ff000000.serial/tty/ttyAMA0/power/wakeup
- GPIO
- If enabled as a wake-up source, a GPIO event will trigger the kernel to resume
from the suspend mode.
- Required Kernel Configurations
-
- Device Drivers
- Input device support, [*]
- Generic input layer (needed for keyboard, mouse, ...) (INPUT [=y])
- [*] Keyboards (INPUT_KEYBOARD [=y])
- [*] GPIO Buttons (CONFIG_KEYBOARD_GPIO=y)
- [*] Polled GPIO buttons
- Example Code
- To wake up the APU on the GPIO
pin:
$ echo enabled > /sys/devices/platform/gpio-keys/power/wakeup