1 // SPDX-License-Identifier: GPL-2.0-or-later
2 #include <linux/module.h>
3 #include <linux/sched/signal.h>
4 #include <linux/acpi.h>
5 #include <acpi/button.h>
6 
7 MODULE_AUTHOR("Josh Triplett");
8 MODULE_DESCRIPTION("ACPI Tiny Power Button Driver");
9 MODULE_LICENSE("GPL");
10 
11 static int power_signal __read_mostly = CONFIG_ACPI_TINY_POWER_BUTTON_SIGNAL;
12 module_param(power_signal, int, 0644);
13 MODULE_PARM_DESC(power_signal, "Power button sends this signal to init");
14 
15 static const struct acpi_device_id tiny_power_button_device_ids[] = {
16 	{ ACPI_BUTTON_HID_POWER, 0 },
17 	{ ACPI_BUTTON_HID_POWERF, 0 },
18 	{ "", 0 },
19 };
20 MODULE_DEVICE_TABLE(acpi, tiny_power_button_device_ids);
21 
22 static int acpi_noop_add_remove(struct acpi_device *device)
23 {
24 	return 0;
25 }
26 
27 static void acpi_tiny_power_button_notify(struct acpi_device *device, u32 event)
28 {
29 	kill_cad_pid(power_signal, 1);
30 }
31 
32 static struct acpi_driver acpi_tiny_power_button_driver = {
33 	.name = "tiny-power-button",
34 	.class = "tiny-power-button",
35 	.ids = tiny_power_button_device_ids,
36 	.ops = {
37 		.add = acpi_noop_add_remove,
38 		.remove = acpi_noop_add_remove,
39 		.notify = acpi_tiny_power_button_notify,
40 	},
41 };
42 
43 module_driver(acpi_tiny_power_button_driver,
44 		acpi_bus_register_driver,
45 		acpi_bus_unregister_driver);
46