xref: /linux/drivers/acpi/acpi_watchdog.c (revision db6d8d5fdf9537641c76ba7f32e02b4bcc600972)
1 /*
2  * ACPI watchdog table parsing support.
3  *
4  * Copyright (C) 2016, Intel Corporation
5  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11 
12 #define pr_fmt(fmt) "ACPI: watchdog: " fmt
13 
14 #include <linux/acpi.h>
15 #include <linux/ioport.h>
16 #include <linux/platform_device.h>
17 
18 #include "internal.h"
19 
20 /**
21  * Returns true if this system should prefer ACPI based watchdog instead of
22  * the native one (which are typically the same hardware).
23  */
24 bool acpi_has_watchdog(void)
25 {
26 	struct acpi_table_header hdr;
27 
28 	if (acpi_disabled)
29 		return false;
30 
31 	return ACPI_SUCCESS(acpi_get_table_header(ACPI_SIG_WDAT, 0, &hdr));
32 }
33 EXPORT_SYMBOL_GPL(acpi_has_watchdog);
34 
35 void __init acpi_watchdog_init(void)
36 {
37 	const struct acpi_wdat_entry *entries;
38 	const struct acpi_table_wdat *wdat;
39 	struct list_head resource_list;
40 	struct resource_entry *rentry;
41 	struct platform_device *pdev;
42 	struct resource *resources;
43 	size_t nresources = 0;
44 	acpi_status status;
45 	int i;
46 
47 	status = acpi_get_table(ACPI_SIG_WDAT, 0,
48 				(struct acpi_table_header **)&wdat);
49 	if (ACPI_FAILURE(status)) {
50 		/* It is fine if there is no WDAT */
51 		return;
52 	}
53 
54 	/* Watchdog disabled by BIOS */
55 	if (!(wdat->flags & ACPI_WDAT_ENABLED))
56 		return;
57 
58 	/* Skip legacy PCI WDT devices */
59 	if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
60 	    wdat->pci_device != 0xff || wdat->pci_function != 0xff)
61 		return;
62 
63 	INIT_LIST_HEAD(&resource_list);
64 
65 	entries = (struct acpi_wdat_entry *)(wdat + 1);
66 	for (i = 0; i < wdat->entries; i++) {
67 		const struct acpi_generic_address *gas;
68 		struct resource_entry *rentry;
69 		struct resource res;
70 		bool found;
71 
72 		gas = &entries[i].register_region;
73 
74 		res.start = gas->address;
75 		if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
76 			res.flags = IORESOURCE_MEM;
77 			res.end = res.start + ALIGN(gas->access_width, 4);
78 		} else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
79 			res.flags = IORESOURCE_IO;
80 			res.end = res.start + gas->access_width;
81 		} else {
82 			pr_warn("Unsupported address space: %u\n",
83 				gas->space_id);
84 			goto fail_free_resource_list;
85 		}
86 
87 		found = false;
88 		resource_list_for_each_entry(rentry, &resource_list) {
89 			if (resource_contains(rentry->res, &res)) {
90 				found = true;
91 				break;
92 			}
93 		}
94 
95 		if (!found) {
96 			rentry = resource_list_create_entry(NULL, 0);
97 			if (!rentry)
98 				goto fail_free_resource_list;
99 
100 			*rentry->res = res;
101 			resource_list_add_tail(rentry, &resource_list);
102 			nresources++;
103 		}
104 	}
105 
106 	resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
107 	if (!resources)
108 		goto fail_free_resource_list;
109 
110 	i = 0;
111 	resource_list_for_each_entry(rentry, &resource_list)
112 		resources[i++] = *rentry->res;
113 
114 	pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
115 					       resources, nresources);
116 	if (IS_ERR(pdev))
117 		pr_err("Failed to create platform device\n");
118 
119 	kfree(resources);
120 
121 fail_free_resource_list:
122 	resource_list_free(&resource_list);
123 }
124