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
7MODULE_AUTHOR("Josh Triplett");
8MODULE_DESCRIPTION("ACPI Tiny Power Button Driver");
9MODULE_LICENSE("GPL");
10
11static int power_signal __read_mostly = CONFIG_ACPI_TINY_POWER_BUTTON_SIGNAL;
12module_param(power_signal, int, 0644);
13MODULE_PARM_DESC(power_signal, "Power button sends this signal to init");
14
15static 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};
20MODULE_DEVICE_TABLE(acpi, tiny_power_button_device_ids);
21
22static void acpi_tiny_power_button_notify(acpi_handle handle, u32 event, void *data)
23{
24	kill_cad_pid(power_signal, 1);
25}
26
27static void acpi_tiny_power_button_notify_run(void *not_used)
28{
29	acpi_tiny_power_button_notify(NULL, ACPI_FIXED_HARDWARE_EVENT, NULL);
30}
31
32static u32 acpi_tiny_power_button_event(void *not_used)
33{
34	acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_tiny_power_button_notify_run, NULL);
35	return ACPI_INTERRUPT_HANDLED;
36}
37
38static int acpi_tiny_power_button_add(struct acpi_device *device)
39{
40	acpi_status status;
41
42	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) {
43		status = acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
44							  acpi_tiny_power_button_event,
45							  NULL);
46	} else {
47		status = acpi_install_notify_handler(device->handle,
48						     ACPI_DEVICE_NOTIFY,
49						     acpi_tiny_power_button_notify,
50						     NULL);
51	}
52	if (ACPI_FAILURE(status))
53		return -ENODEV;
54
55	return 0;
56}
57
58static void acpi_tiny_power_button_remove(struct acpi_device *device)
59{
60	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) {
61		acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
62						acpi_tiny_power_button_event);
63	} else {
64		acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
65					   acpi_tiny_power_button_notify);
66	}
67	acpi_os_wait_events_complete();
68}
69
70static struct acpi_driver acpi_tiny_power_button_driver = {
71	.name = "tiny-power-button",
72	.class = "tiny-power-button",
73	.ids = tiny_power_button_device_ids,
74	.ops = {
75		.add = acpi_tiny_power_button_add,
76		.remove = acpi_tiny_power_button_remove,
77	},
78};
79
80module_acpi_driver(acpi_tiny_power_button_driver);
81