[nrf fromtree] samples: boards: nrf: system_off: use sys_poweroff

Make use of the new sys_poweroff API to actually power off the system.
This lets us remove many hacks present in the sample.

Signed-off-by: Gerard Marull-Paretas <[email protected]>
(cherry picked from commit 37b26f4)

Author: gmarull

samples/boards/nrf/system_off/prj.conf

@@ -1,7 +1,7 @@
-CONFIG_PM=y
 # Required to disable default behavior of deep sleep on timeout
 CONFIG_PM_DEVICE=y
 CONFIG_GPIO=y
 # Optional select RAM retention (nRF52 only)
 #CONFIG_APP_RETENTION=y
 CONFIG_CRC=y
+CONFIG_POWEROFF=y

samples/boards/nrf/system_off/src/main.c

@@ -7,32 +7,15 @@
 #include <stdio.h>
 #include <zephyr/kernel.h>
 #include <zephyr/device.h>
-#include <zephyr/init.h>
-#include <zephyr/pm/pm.h>
 #include <zephyr/pm/device.h>
-#include <zephyr/pm/policy.h>
+#include <zephyr/sys/poweroff.h>
 #include <soc.h>
 #include "retained.h"
 #include <hal/nrf_gpio.h>
 
 #define BUSY_WAIT_S 2U
 #define SLEEP_S 2U
 
-/* Prevent deep sleep (system off) from being entered on long timeouts
- * or `K_FOREVER` due to the default residency policy.
- *
- * This has to be done before anything tries to sleep, which means
- * before the threading system starts up.
- */
-static int disable_ds_1(void)
-{
-
-	pm_policy_state_lock_get(PM_STATE_SOFT_OFF, PM_ALL_SUBSTATES);
-	return 0;
-}
-
-SYS_INIT(disable_ds_1, PRE_KERNEL_1, 99);
-
 int main(void)
 {
 	int rc;
@@ -90,21 +73,7 @@ int main(void)
 		retained_update();
 	}
 
-	/* Above we disabled entry to deep sleep based on duration of
-	 * controlled delay.  Here we need to override that, then
-	 * force entry to deep sleep on any delay.
-	 */
-	pm_state_force(0u, &(struct pm_state_info){PM_STATE_SOFT_OFF, 0, 0});
+	sys_poweroff();
 
-	/* Now we need to go sleep. This will let the idle thread runs and
-	 * the pm subsystem will use the forced state. To confirm that the
-	 * forced state is used, lets set the same timeout used previously.
-	 */
-	k_sleep(K_SECONDS(SLEEP_S));
-
-	printk("ERROR: System off failed\n");
-	while (true) {
-		/* spin to avoid fall-off behavior */
-	}
 	return 0;
 }