ACPI: tiny-power-button: Eliminate the driver notify callback

Rework the ACPI tiny-power-button driver to install a notify handler or
a fixed event handler for the device it binds to by itself and drop its
notify callback.

This will allow acpi_device_install_notify_handler() and
acpi_device_remove_notify_handler() to be simplified going forward.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/tiny-power-button.c

@@ -19,18 +19,52 @@ static const struct acpi_device_id tiny_power_button_device_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, tiny_power_button_device_ids);
 
-static int acpi_noop_add(struct acpi_device *device)
+static void acpi_tiny_power_button_notify(acpi_handle handle, u32 event, void *data)
 {
-	return 0;
+	kill_cad_pid(power_signal, 1);
 }
 
-static void acpi_noop_remove(struct acpi_device *device)
+static void acpi_tiny_power_button_notify_run(void *not_used)
 {
+	acpi_tiny_power_button_notify(NULL, ACPI_FIXED_HARDWARE_EVENT, NULL);
 }
 
-static void acpi_tiny_power_button_notify(struct acpi_device *device, u32 event)
+static u32 acpi_tiny_power_button_event(void *not_used)
 {
-	kill_cad_pid(power_signal, 1);
+	acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_tiny_power_button_notify_run, NULL);
+	return ACPI_INTERRUPT_HANDLED;
+}
+
+static int acpi_tiny_power_button_add(struct acpi_device *device)
+{
+	acpi_status status;
+
+	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) {
+		status = acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
+							  acpi_tiny_power_button_event,
+							  NULL);
+	} else {
+		status = acpi_install_notify_handler(device->handle,
+						     ACPI_DEVICE_NOTIFY,
+						     acpi_tiny_power_button_notify,
+						     NULL);
+	}
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	return 0;
+}
+
+static void acpi_tiny_power_button_remove(struct acpi_device *device)
+{
+	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) {
+		acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
+						acpi_tiny_power_button_event);
+	} else {
+		acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+					   acpi_tiny_power_button_notify);
+	}
+	acpi_os_wait_events_complete();
 }
 
 static struct acpi_driver acpi_tiny_power_button_driver = {
@@ -38,9 +72,8 @@ static struct acpi_driver acpi_tiny_power_button_driver = {
 	.class = "tiny-power-button",
 	.ids = tiny_power_button_device_ids,
 	.ops = {
-		.add = acpi_noop_add,
-		.remove = acpi_noop_remove,
-		.notify = acpi_tiny_power_button_notify,
+		.add = acpi_tiny_power_button_add,
+		.remove = acpi_tiny_power_button_remove,
 	},
 };