Power / restart key handlers (<tt>RT_INPUT_POWER</tt>)

**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: Input device model (DM). Handler API: Input subsystem.

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.

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.

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).

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.

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 Input userspace API (UAPI)
Hold-to-power-off	Not implemented here — implement in driver (long-press timer) before reporting release

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)