1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ACPI watchdog table parsing support.
4 *
5 * Copyright (C) 2016, Intel Corporation
6 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
7 */
8
9 #define pr_fmt(fmt) "ACPI: watchdog: " fmt
10
11 #include <linux/acpi.h>
12 #include <linux/ioport.h>
13 #include <linux/platform_device.h>
14
15 #include "internal.h"
16
17 #ifdef CONFIG_RTC_MC146818_LIB
18 #include <linux/mc146818rtc.h>
19
20 /*
21 * There are several systems where the WDAT table is accessing RTC SRAM to
22 * store persistent information. This does not work well with the Linux RTC
23 * driver so on those systems we skip WDAT driver and prefer iTCO_wdt
24 * instead.
25 *
26 * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033.
27 */
acpi_watchdog_uses_rtc(const struct acpi_table_wdat * wdat)28 static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
29 {
30 const struct acpi_wdat_entry *entries;
31 int i;
32
33 entries = (struct acpi_wdat_entry *)(wdat + 1);
34 for (i = 0; i < wdat->entries; i++) {
35 const struct acpi_generic_address *gas;
36
37 gas = &entries[i].register_region;
38 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
39 switch (gas->address) {
40 case RTC_PORT(0):
41 case RTC_PORT(1):
42 case RTC_PORT(2):
43 case RTC_PORT(3):
44 return true;
45 }
46 }
47 }
48
49 return false;
50 }
51 #else
acpi_watchdog_uses_rtc(const struct acpi_table_wdat * wdat)52 static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
53 {
54 return false;
55 }
56 #endif
57
acpi_watchdog_get_wdat(void)58 static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
59 {
60 const struct acpi_table_wdat *wdat = NULL;
61 acpi_status status;
62
63 if (acpi_disabled)
64 return NULL;
65
66 status = acpi_get_table(ACPI_SIG_WDAT, 0,
67 (struct acpi_table_header **)&wdat);
68 if (ACPI_FAILURE(status)) {
69 /* It is fine if there is no WDAT */
70 return NULL;
71 }
72
73 if (acpi_watchdog_uses_rtc(wdat)) {
74 pr_info("Skipping WDAT on this system because it uses RTC SRAM\n");
75 return NULL;
76 }
77
78 return wdat;
79 }
80
81 /**
82 * Returns true if this system should prefer ACPI based watchdog instead of
83 * the native one (which are typically the same hardware).
84 */
acpi_has_watchdog(void)85 bool acpi_has_watchdog(void)
86 {
87 return !!acpi_watchdog_get_wdat();
88 }
89 EXPORT_SYMBOL_GPL(acpi_has_watchdog);
90
acpi_watchdog_init(void)91 void __init acpi_watchdog_init(void)
92 {
93 const struct acpi_wdat_entry *entries;
94 const struct acpi_table_wdat *wdat;
95 struct list_head resource_list;
96 struct resource_entry *rentry;
97 struct platform_device *pdev;
98 struct resource *resources;
99 size_t nresources = 0;
100 int i;
101
102 wdat = acpi_watchdog_get_wdat();
103 if (!wdat) {
104 /* It is fine if there is no WDAT */
105 return;
106 }
107
108 /* Watchdog disabled by BIOS */
109 if (!(wdat->flags & ACPI_WDAT_ENABLED))
110 return;
111
112 /* Skip legacy PCI WDT devices */
113 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
114 wdat->pci_device != 0xff || wdat->pci_function != 0xff)
115 return;
116
117 INIT_LIST_HEAD(&resource_list);
118
119 entries = (struct acpi_wdat_entry *)(wdat + 1);
120 for (i = 0; i < wdat->entries; i++) {
121 const struct acpi_generic_address *gas;
122 struct resource_entry *rentry;
123 struct resource res = {};
124 bool found;
125
126 gas = &entries[i].register_region;
127
128 res.start = gas->address;
129 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
130 res.flags = IORESOURCE_MEM;
131 res.end = res.start + ALIGN(gas->access_width, 4) - 1;
132 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
133 res.flags = IORESOURCE_IO;
134 res.end = res.start + gas->access_width - 1;
135 } else {
136 pr_warn("Unsupported address space: %u\n",
137 gas->space_id);
138 goto fail_free_resource_list;
139 }
140
141 found = false;
142 resource_list_for_each_entry(rentry, &resource_list) {
143 if (rentry->res->flags == res.flags &&
144 resource_overlaps(rentry->res, &res)) {
145 if (res.start < rentry->res->start)
146 rentry->res->start = res.start;
147 if (res.end > rentry->res->end)
148 rentry->res->end = res.end;
149 found = true;
150 break;
151 }
152 }
153
154 if (!found) {
155 rentry = resource_list_create_entry(NULL, 0);
156 if (!rentry)
157 goto fail_free_resource_list;
158
159 *rentry->res = res;
160 resource_list_add_tail(rentry, &resource_list);
161 nresources++;
162 }
163 }
164
165 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
166 if (!resources)
167 goto fail_free_resource_list;
168
169 i = 0;
170 resource_list_for_each_entry(rentry, &resource_list)
171 resources[i++] = *rentry->res;
172
173 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
174 resources, nresources);
175 if (IS_ERR(pdev))
176 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev));
177
178 kfree(resources);
179
180 fail_free_resource_list:
181 resource_list_free(&resource_list);
182 }
183