1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 97450f4003cc..f007116a8427 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -484,6 +484,25 @@ void acpi_dev_power_up_children_with_adr(struct acpi_device *adev)
 	acpi_dev_for_each_child(adev, acpi_power_up_if_adr_present, NULL);
 }
 
+/**
+ * acpi_dev_power_state_for_wake - Deepest power state for wakeup signaling
+ * @adev: ACPI companion of the target device.
+ *
+ * Evaluate _S0W for @adev and return the value produced by it or return
+ * ACPI_STATE_UNKNOWN on errors (including _S0W not present).
+ */
+u8 acpi_dev_power_state_for_wake(struct acpi_device *adev)
+{
+	unsigned long long state;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(adev->handle, "_S0W", NULL, &state);
+	if (ACPI_FAILURE(status))
+		return ACPI_STATE_UNKNOWN;
+
+	return state;
+}
+
 #ifdef CONFIG_PM
 static DEFINE_MUTEX(acpi_pm_notifier_lock);
 static DEFINE_MUTEX(acpi_pm_notifier_install_lock);