rt-thread/documentation/6.components/device-driver/input/power.md

@page page_device_input_power Input power keys

Power / restart key handlers (RT_INPUT_POWER)

input_power.c installs global rt_input_handler instances that map KEY_POWER and KEY_RESTART release events to rt_hw_cpu_shutdown() and rt_hw_cpu_reset(). Any input device that advertises these keys in its capability bitmap can trigger system power actions without a dedicated PMIC driver hook.

DM and keyboard drivers: @ref page_device_input_dm. Handler API: @ref page_device_input.

Source: components/drivers/input/input_power.c.

---

Kconfig

Option	Default	Role
RT_INPUT_POWER	y	Build input_power.c, run input_event_power_init at env init

Depends on RT_USING_INPUT. Disable on boards where KEY_POWER must only be handled by application code.

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Architecture

  INIT_ENV_EXPORT(input_event_power_init)
        |
        +-- power_handler_install(KEY_POWER)
        +-- power_handler_install(KEY_RESTART)
                |
                |  (1) tmp_handler: identify=test, callback=power_input_callback
                |      rt_input_add_handler → scans all idevs, counts matches
                v
        (2) For each matching input device index:
                alloc rt_input_handler[N]
                identify=power_input_identify (binds to Nth device with key)
                callback=power_input_callback
                rt_input_add_handler
        |
        v
  Any idev reports KEY_POWER/KEY_RESTART release (value==0)
        → rt_input_event → handler → shutdown/reset

Phase	Behavior
Probe pass	Temporary handler increments cap.value for each rt_input_device with key_map[code] set
Install pass	One persistent handler per matching device; identify matches the current-th device
Runtime	power_input_callback: on value == 0 (key release), call BSP hook

Handlers return RT_TRUE from callback to stop further handler dispatch for that event.

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Key actions

Linux code	Event	Action
KEY_POWER (116)	EV_KEY, value == 0 (release)	rt_hw_cpu_shutdown()
KEY_RESTART	EV_KEY, value == 0	rt_hw_cpu_reset()

Press (value == 1) does nothing in input_power.c — only release triggers power ops.

BSP must implement rt_hw_cpu_shutdown / rt_hw_cpu_reset (weak symbols or SoC-specific).

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Interaction with drivers

• gpio-keys child with linux,code = <116> registers an inputN with KEY_POWER in key_map — power handler attaches automatically when RT_INPUT_POWER is on.
• ettus,e3x0-button reports KEY_POWER on IRQ — same path.
• Does not require a dedicated compatible string; only the advertised key code matters.

If multiple devices expose KEY_POWER, each gets its own handler instance; any of them can shut down the system on release.

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Disabling or overriding

Goal	Approach
No automatic shutdown	Set RT_INPUT_POWER=n in Kconfig
Custom policy	Disable RT_INPUT_POWER and use rt_input_add_handler with higher priority logic, or handle KEY_POWER only in userspace via @ref page_device_input_uapi
Hold-to-power-off	Not implemented here — implement in driver (long-press timer) before reporting release

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Pitfalls

Issue	Mitigation
Unexpected shutdown	Any stray KEY_POWER release shuts down — verify DT linux,code and test harnesses
Missing capability	Driver must rt_input_set_capability(idev, EV_KEY, KEY_POWER) before register
Press-only testing	Release is required — press alone does not call shutdown
No matching devices	power_handler_install exits early if count is zero (no handlers allocated)

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See also

• @ref page_device_input_dm — gpio-keys DT example with KEY_POWER
• @ref page_device_input
• dt-bindings/input/linux-event-codes.h (or event-codes.h)