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
58 static bool acpi_no_watchdog;
59
acpi_watchdog_get_wdat(void)60 static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
61 {
62 const struct acpi_table_wdat *wdat = NULL;
63 acpi_status status;
64
65 if (acpi_disabled || acpi_no_watchdog)
66 return NULL;
67
68 status = acpi_get_table(ACPI_SIG_WDAT, 0,
69 (struct acpi_table_header **)&wdat);
70 if (ACPI_FAILURE(status)) {
71 /* It is fine if there is no WDAT */
72 return NULL;
73 }
74
75 if (acpi_watchdog_uses_rtc(wdat)) {
76 acpi_put_table((struct acpi_table_header *)wdat);
77 pr_info("Skipping WDAT on this system because it uses RTC SRAM\n");
78 return NULL;
79 }
80
81 return wdat;
82 }
83
84 /**
85 * Returns true if this system should prefer ACPI based watchdog instead of
86 * the native one (which are typically the same hardware).
87 */
acpi_has_watchdog(void)88 bool acpi_has_watchdog(void)
89 {
90 return !!acpi_watchdog_get_wdat();
91 }
92 EXPORT_SYMBOL_GPL(acpi_has_watchdog);
93
94 /* ACPI watchdog can be disabled on boot command line */
disable_acpi_watchdog(char * str)95 static int __init disable_acpi_watchdog(char *str)
96 {
97 acpi_no_watchdog = true;
98 return 1;
99 }
100 __setup("acpi_no_watchdog", disable_acpi_watchdog);
101
acpi_watchdog_init(void)102 void __init acpi_watchdog_init(void)
103 {
104 const struct acpi_wdat_entry *entries;
105 const struct acpi_table_wdat *wdat;
106 struct list_head resource_list;
107 struct resource_entry *rentry;
108 struct platform_device *pdev;
109 struct resource *resources;
110 size_t nresources = 0;
111 int i;
112
113 wdat = acpi_watchdog_get_wdat();
114 if (!wdat) {
115 /* It is fine if there is no WDAT */
116 return;
117 }
118
119 /* Watchdog disabled by BIOS */
120 if (!(wdat->flags & ACPI_WDAT_ENABLED))
121 goto fail_put_wdat;
122
123 /* Skip legacy PCI WDT devices */
124 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
125 wdat->pci_device != 0xff || wdat->pci_function != 0xff)
126 goto fail_put_wdat;
127
128 INIT_LIST_HEAD(&resource_list);
129
130 entries = (struct acpi_wdat_entry *)(wdat + 1);
131 for (i = 0; i < wdat->entries; i++) {
132 const struct acpi_generic_address *gas;
133 struct resource_entry *rentry;
134 struct resource res = {};
135 bool found;
136
137 gas = &entries[i].register_region;
138
139 res.start = gas->address;
140 res.end = res.start + ACPI_ACCESS_BYTE_WIDTH(gas->access_width) - 1;
141 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
142 res.flags = IORESOURCE_MEM;
143 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
144 res.flags = IORESOURCE_IO;
145 } else {
146 pr_warn("Unsupported address space: %u\n",
147 gas->space_id);
148 goto fail_free_resource_list;
149 }
150
151 found = false;
152 resource_list_for_each_entry(rentry, &resource_list) {
153 if (rentry->res->flags == res.flags &&
154 resource_union(rentry->res, &res, rentry->res)) {
155 found = true;
156 break;
157 }
158 }
159
160 if (!found) {
161 rentry = resource_list_create_entry(NULL, 0);
162 if (!rentry)
163 goto fail_free_resource_list;
164
165 *rentry->res = res;
166 resource_list_add_tail(rentry, &resource_list);
167 nresources++;
168 }
169 }
170
171 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
172 if (!resources)
173 goto fail_free_resource_list;
174
175 i = 0;
176 resource_list_for_each_entry(rentry, &resource_list)
177 resources[i++] = *rentry->res;
178
179 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
180 resources, nresources);
181 if (IS_ERR(pdev))
182 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev));
183
184 kfree(resources);
185
186 fail_free_resource_list:
187 resource_list_free(&resource_list);
188 fail_put_wdat:
189 acpi_put_table((struct acpi_table_header *)wdat);
190 }
191