1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  EFI watchdog
4  *
5  *  Copyright (c) 2017 Heinrich Schuchardt
6  */
7 
8 #include <common.h>
9 #include <efi_loader.h>
10 
11 /* Conversion factor from seconds to multiples of 100ns */
12 #define EFI_SECONDS_TO_100NS 10000000ULL
13 
14 static struct efi_event *watchdog_timer_event;
15 
16 /*
17  * Reset the system when the watchdog event is notified.
18  *
19  * @event:	the watchdog event
20  * @context:	not used
21  */
22 static void EFIAPI efi_watchdog_timer_notify(struct efi_event *event,
23 					     void *context)
24 {
25 	EFI_ENTRY("%p, %p", event, context);
26 
27 	printf("\nEFI: Watchdog timeout\n");
28 	EFI_CALL_VOID(efi_runtime_services.reset_system(EFI_RESET_COLD,
29 							EFI_SUCCESS, 0, NULL));
30 
31 	EFI_EXIT(EFI_UNSUPPORTED);
32 }
33 
34 /*
35  * Reset the watchdog timer.
36  *
37  * This function is used by the SetWatchdogTimer service.
38  *
39  * @timeout:		seconds before reset by watchdog
40  * @return:		status code
41  */
42 efi_status_t efi_set_watchdog(unsigned long timeout)
43 {
44 	efi_status_t r;
45 
46 	if (timeout)
47 		/* Reset watchdog */
48 		r = efi_set_timer(watchdog_timer_event, EFI_TIMER_RELATIVE,
49 				  EFI_SECONDS_TO_100NS * timeout);
50 	else
51 		/* Deactivate watchdog */
52 		r = efi_set_timer(watchdog_timer_event, EFI_TIMER_STOP, 0);
53 	return r;
54 }
55 
56 /*
57  * Initialize the EFI watchdog.
58  *
59  * This function is called by efi_init_obj_list()
60  */
61 efi_status_t efi_watchdog_register(void)
62 {
63 	efi_status_t r;
64 
65 	/*
66 	 * Create a timer event.
67 	 */
68 	r = efi_create_event(EVT_TIMER | EVT_NOTIFY_SIGNAL, TPL_CALLBACK,
69 			     efi_watchdog_timer_notify, NULL, NULL,
70 			     &watchdog_timer_event);
71 	if (r != EFI_SUCCESS) {
72 		printf("ERROR: Failed to register watchdog event\n");
73 		return r;
74 	}
75 	/*
76 	 * The UEFI standard requires that the watchdog timer is set to five
77 	 * minutes when invoking an EFI boot option.
78 	 *
79 	 * Unified Extensible Firmware Interface (UEFI), version 2.7 Errata A
80 	 * 7.5. Miscellaneous Boot Services - EFI_BOOT_SERVICES.SetWatchdogTimer
81 	 */
82 	r = efi_set_watchdog(300);
83 	if (r != EFI_SUCCESS) {
84 		printf("ERROR: Failed to set watchdog timer\n");
85 		return r;
86 	}
87 	return EFI_SUCCESS;
88 }
89