Board-level shutdown and restart

**components/drivers/power/reset/** — drivers that hook system-wide power off or CPU reset, not per-IP reset lines (Reset controller).

Kconfig: **RT_USING_POWER_RESET**, plus **RT_POWER_RESET_GPIO_*** or **RT_POWER_RESET_SYSCON_***.

API header: **components/drivers/include/drivers/core/power.h** — details in System power off and reboot (core).

Registration model

These drivers are platform drivers whose **probe** registers a callback with the DM power core. They do not register a char device for normal I/O.

RT_PLATFORM_DRIVER_EXPORT(gpio_poweroff_driver)
        |
        v
gpio_poweroff_probe(pdev)
        |
        +-- parse GPIO (rt_pin_get_named_pin) or syscon reg
        +-- rt_dm_power_off_handler(dev, MODE, PRIORITY, callback)
        |
        v
On rt_hw_cpu_shutdown() / rt_hw_cpu_reset():
        walk handlers by priority → callback → rt_dm_machine_shutdown/reset

<tt>rt_dm_power_off_handler</tt>

rt_err_t rt_dm_power_off_handler(struct rt_device *dev, int mode, int priority,

rt_err_t (*callback)(struct rt_device *));

rt_device

Definition: rtdef.h:1369

`mode`	When invoked
`RT_DM_POWER_OFF_MODE_SHUTDOWN`	System power off (`rt_hw_cpu_shutdown`)
`RT_DM_POWER_OFF_MODE_RESET`	Warm reset path (`rt_hw_cpu_reset`)

`priority` (low → high)	Typical use
`RT_DM_POWER_OFF_PRIO_PLATFORM`	SoC flush
`RT_DM_POWER_OFF_PRIO_LOW` / `DEFAULT` / `HIGH`	Drivers, filesystem sync
`RT_DM_POWER_OFF_PRIO_FIRMWARE`	Last handoff

Callbacks run in order; non-**RT_EOK** is logged but later handlers still run.

**dev**: passed to callback as **dev->user_data** context holder (GPIO drivers store private struct in **user_data**).

In-tree drivers

Driver	Compatible / binding	Registration
`gpio-poweroff`	`gpio-poweroff`	`RT_DM_POWER_OFF_MODE_SHUTDOWN`, `rt_pin_get_named_pin`
`gpio-restart`	`gpio-restart`	`RT_DM_POWER_OFF_MODE_RESET`
`syscon-poweroff`	syscon reg	MMIO write in callback
`syscon-reboot`	syscon reg	reset trigger
`syscon-reboot-mode`	NVMEM + syscon	`rt_dm_reboot_mode_register`

All use **RT_PLATFORM_DRIVER_EXPORT** except some syscon drivers use **INIT_SUBSYS_EXPORT + rt_platform_driver_register** (same binding, different init level — see Platform bus).

GPIO poweroff example (flow)

static rt_err_t gpio_poweroff_do_poweroff(struct rt_device *dev)
{
    struct gpio_poweroff *gp = dev->user_data;
    /* assert GPIO sequence, mdelay per DT timeout-ms */
    return RT_EOK;
}
 
static rt_err_t gpio_poweroff_probe(struct rt_platform_device *pdev)
{
    ...
    dev->user_data = gp;
    return rt_dm_power_off_handler(dev, RT_DM_POWER_OFF_MODE_SHUTDOWN,
            RT_DM_POWER_OFF_PRIO_DEFAULT, gpio_poweroff_do_poweroff);
}
RT_PLATFORM_DRIVER_EXPORT(gpio_poweroff_driver);

DT:

poweroff {
    compatible = "gpio-poweroff";
    gpios = <&gpio0 99 GPIO_ACTIVE_HIGH>;
    timeout-ms = <3000>;
    active-delay-ms = <100>;
    inactive-delay-ms = <100>;
};

Reboot mode

rt_dm_reboot_mode_register(dev, reboot_mode_callback);

rt_hw_cpu_reset_mode("recovery"); /* sets cmd + rt_hw_cpu_reset() */

**syscon-reboot-mode** persists mode to NVMEM/syscon so the next boot loader can read it. See **reboot-mode.h**, System power off and reboot (core).

Machine hooks

BSP sets after handlers:

rt_dm_machine_shutdown = board_shutdown; /* PMIC off */

rt_dm_machine_reset = board_reset; /* PSCI / watchdog */

Without these, callbacks may run but SoC never powers off.

Pitfalls

Issue	Mitigation
Wrong GPIO polarity	Match `gpios` flags and `active_value` from `rt_pin_get_named_pin`
`RT_USING_PINCTRL` off for gpio-poweroff	Kconfig depends on pinctrl for pad mux
Confuse with `rt_reset_control`	IP reset lines ≠ system poweroff
Handler sleeps in IRQ context	GPIO driver uses `rt_thread_mdelay` — ensure thread context
No `rt_dm_machine_shutdown`	Set BSP hook

`mode`	When invoked
`RT_DM_POWER_OFF_MODE_SHUTDOWN`	System power off (`rt_hw_cpu_shutdown`)
`RT_DM_POWER_OFF_MODE_RESET`	Warm reset path (`rt_hw_cpu_reset`)