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 void acpi_tiny_power_button_notify(acpi_handle handle, u32 event, void *data)
23 {
24 	kill_cad_pid(power_signal, 1);
25 }
26 
27 static 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 
32 static 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 
38 static 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 
58 static 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 
70 static 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 
80 module_acpi_driver(acpi_tiny_power_button_driver);
81