ACPI: power: Switch to sys-off handler API

Switch to sys-off API that replaces legacy pm_power_off callbacks,
allowing us to remove global pm_* variables and support chaining of
all restart and power-off modes consistently.
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sleep.c

@@ -1023,20 +1023,22 @@ static void acpi_sleep_hibernate_setup(void)
 static inline void acpi_sleep_hibernate_setup(void) {}
 #endif /* !CONFIG_HIBERNATION */
 
-static void acpi_power_off_prepare(void)
+static int acpi_power_off_prepare(struct sys_off_data *data)
 {
 	/* Prepare to power off the system */
 	acpi_sleep_prepare(ACPI_STATE_S5);
 	acpi_disable_all_gpes();
 	acpi_os_wait_events_complete();
+	return NOTIFY_DONE;
 }
 
-static void acpi_power_off(void)
+static int acpi_power_off(struct sys_off_data *data)
 {
 	/* acpi_sleep_prepare(ACPI_STATE_S5) should have already been called */
 	pr_debug("%s called\n", __func__);
 	local_irq_disable();
 	acpi_enter_sleep_state(ACPI_STATE_S5);
+	return NOTIFY_DONE;
 }
 
 int __init acpi_sleep_init(void)
@@ -1055,8 +1057,14 @@ int __init acpi_sleep_init(void)
 
 	if (acpi_sleep_state_supported(ACPI_STATE_S5)) {
 		sleep_states[ACPI_STATE_S5] = 1;
-		pm_power_off_prepare = acpi_power_off_prepare;
-		pm_power_off = acpi_power_off;
+
+		register_sys_off_handler(SYS_OFF_MODE_POWER_OFF_PREPARE,
+					 SYS_OFF_PRIO_FIRMWARE,
+					 acpi_power_off_prepare, NULL);
+
+		register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+					 SYS_OFF_PRIO_FIRMWARE,
+					 acpi_power_off, NULL);
 	} else {
 		acpi_no_s5 = true;
 	}