PM: Introduce new PMSG_POWEROFF event

PMSG_POWEROFF will be used for the PM core to allow differentiating between
a hibernation or shutdown sequence when re-using callbacks for common code.

Hibernation is started by writing a hibernation method (such as 'platform'
'shutdown', or 'reboot') to use into /sys/power/disk and writing 'disk' to
/sys/power/state.

Shutdown is initiated with the reboot() syscall with arguments on whether
to halt the system or power it off.

Tested-by: Eric Naim <[e-mail]>
Signed-off-by: Mario Limonciello (AMD) <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/base/power/main.c

···
 		return "restore";
 	case PM_EVENT_RECOVER:
 		return "recover";
+	case PM_EVENT_POWEROFF:
+		return "poweroff";
 	default:
 		return "(unknown PM event)";
 	}
···
 	case PM_EVENT_FREEZE:
 	case PM_EVENT_QUIESCE:
 		return ops->freeze;
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_HIBERNATE:
 		return ops->poweroff;
 	case PM_EVENT_THAW:
···
 	case PM_EVENT_FREEZE:
 	case PM_EVENT_QUIESCE:
 		return ops->freeze_late;
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_HIBERNATE:
 		return ops->poweroff_late;
 	case PM_EVENT_THAW:
···
 	case PM_EVENT_FREEZE:
 	case PM_EVENT_QUIESCE:
 		return ops->freeze_noirq;
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_HIBERNATE:
 		return ops->poweroff_noirq;
 	case PM_EVENT_THAW:

include/linux/pm.h

···
  * RECOVER	Creation of a hibernation image or restoration of the main
  *		memory contents from a hibernation image has failed, call
  *		->thaw() and ->complete() for all devices.
+ * POWEROFF	System will poweroff, call ->poweroff() for all devices.
  *
  * The following PM_EVENT_ messages are defined for internal use by
  * kernel subsystems.  They are never issued by the PM core.
···
 #define PM_EVENT_USER		0x0100
 #define PM_EVENT_REMOTE		0x0200
 #define PM_EVENT_AUTO		0x0400
+#define PM_EVENT_POWEROFF	0x0800
 
 #define PM_EVENT_SLEEP		(PM_EVENT_SUSPEND | PM_EVENT_HIBERNATE)
 #define PM_EVENT_USER_SUSPEND	(PM_EVENT_USER | PM_EVENT_SUSPEND)
···
 #define PMSG_QUIESCE	((struct pm_message){ .event = PM_EVENT_QUIESCE, })
 #define PMSG_SUSPEND	((struct pm_message){ .event = PM_EVENT_SUSPEND, })
 #define PMSG_HIBERNATE	((struct pm_message){ .event = PM_EVENT_HIBERNATE, })
+#define PMSG_POWEROFF	((struct pm_message){ .event = PM_EVENT_POWEROFF, })
 #define PMSG_RESUME	((struct pm_message){ .event = PM_EVENT_RESUME, })
 #define PMSG_THAW	((struct pm_message){ .event = PM_EVENT_THAW, })
 #define PMSG_RESTORE	((struct pm_message){ .event = PM_EVENT_RESTORE, })

include/trace/events/power.h

···
 		{ PM_EVENT_HIBERNATE, "hibernate" }, \
 		{ PM_EVENT_THAW, "thaw" }, \
 		{ PM_EVENT_RESTORE, "restore" }, \
-		{ PM_EVENT_RECOVER, "recover" })
+		{ PM_EVENT_RECOVER, "recover" }, \
+		{ PM_EVENT_POWEROFF, "poweroff" })
 
 DEFINE_EVENT(cpu, cpu_frequency,