PM: domains: Enable dev_pm_genpd_suspend|resume() for suspend-to-idle

The dev_pm_genpd_suspend|resume() have so far only been used during the
syscore suspend/resume phases. However, during suspend-to-idle, where the
syscore phases doesn't exist, similar operations are sometimes needed.

An existing example are the timekeeping_suspend|resume() functions, which
are being called both through a registered syscore ops during the syscore
phases, but also as regular functions calls from cpuidle (via
tick_freeze()) during suspend-to-idle.

For similar reasons, let's enable the dev_pm_genpd_suspend|resume() APIs to
be re-used for corresponding CPU devices that are attached to a genpd,
during suspend-to-idle.

Signed-off-by: Ulf Hansson <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/base/power/domain.c

···
 static void genpd_switch_state(struct device *dev, bool suspend)
 {
 	struct generic_pm_domain *genpd;
+	bool use_lock;
 
 	genpd = dev_to_genpd_safe(dev);
 	if (!genpd)
 		return;
 
+	use_lock = genpd_is_irq_safe(genpd);
+
+	if (use_lock)
+		genpd_lock(genpd);
+
 	if (suspend) {
 		genpd->suspended_count++;
-		genpd_sync_power_off(genpd, false, 0);
+		genpd_sync_power_off(genpd, use_lock, 0);
 	} else {
-		genpd_sync_power_on(genpd, false, 0);
+		genpd_sync_power_on(genpd, use_lock, 0);
 		genpd->suspended_count--;
 	}
+
+	if (use_lock)
+		genpd_unlock(genpd);
 }
 
 /**
···
  * @dev: The device that is attached to the genpd, that can be suspended.
  *
  * This routine should typically be called for a device that needs to be
- * suspended during the syscore suspend phase.
+ * suspended during the syscore suspend phase. It may also be called during
+ * suspend-to-idle to suspend a corresponding CPU device that is attached to a
+ * genpd.
  */
 void dev_pm_genpd_suspend(struct device *dev)
 {
···
  * @dev: The device that is attached to the genpd, which needs to be resumed.
  *
  * This routine should typically be called for a device that needs to be resumed
- * during the syscore resume phase.
+ * during the syscore resume phase. It may also be called during suspend-to-idle
+ * to resume a corresponding CPU device that is attached to a genpd.
  */
 void dev_pm_genpd_resume(struct device *dev)
 {