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 #ifdef CONFIG_RTC_MC146818_LIB
21 #include <linux/mc146818rtc.h>
22
23 /*
24 * There are several systems where the WDAT table is accessing RTC SRAM to
25 * store persistent information. This does not work well with the Linux RTC
26 * driver so on those systems we skip WDAT driver and prefer iTCO_wdt
27 * instead.
28 *
29 * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033.
30 */
acpi_watchdog_uses_rtc(const struct acpi_table_wdat * wdat)31 static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
32 {
33 const struct acpi_wdat_entry *entries;
34 int i;
35
36 entries = (struct acpi_wdat_entry *)(wdat + 1);
37 for (i = 0; i < wdat->entries; i++) {
38 const struct acpi_generic_address *gas;
39
40 gas = &entries[i].register_region;
41 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
42 switch (gas->address) {
43 case RTC_PORT(0):
44 case RTC_PORT(1):
45 case RTC_PORT(2):
46 case RTC_PORT(3):
47 return true;
48 }
49 }
50 }
51
52 return false;
53 }
54 #else
acpi_watchdog_uses_rtc(const struct acpi_table_wdat * wdat)55 static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
56 {
57 return false;
58 }
59 #endif
60
61 static bool acpi_no_watchdog;
62
acpi_watchdog_get_wdat(void)63 static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
64 {
65 const struct acpi_table_wdat *wdat = NULL;
66 acpi_status status;
67
68 if (acpi_disabled || acpi_no_watchdog)
69 return NULL;
70
71 status = acpi_get_table(ACPI_SIG_WDAT, 0,
72 (struct acpi_table_header **)&wdat);
73 if (ACPI_FAILURE(status)) {
74 /* It is fine if there is no WDAT */
75 return NULL;
76 }
77
78 if (acpi_watchdog_uses_rtc(wdat)) {
79 pr_info("Skipping WDAT on this system because it uses RTC SRAM\n");
80 return NULL;
81 }
82
83 return wdat;
84 }
85
86 /**
87 * Returns true if this system should prefer ACPI based watchdog instead of
88 * the native one (which are typically the same hardware).
89 */
acpi_has_watchdog(void)90 bool acpi_has_watchdog(void)
91 {
92 return !!acpi_watchdog_get_wdat();
93 }
94 EXPORT_SYMBOL_GPL(acpi_has_watchdog);
95
96 /* ACPI watchdog can be disabled on boot command line */
disable_acpi_watchdog(char * str)97 static int __init disable_acpi_watchdog(char *str)
98 {
99 acpi_no_watchdog = true;
100 return 1;
101 }
102 __setup("acpi_no_watchdog", disable_acpi_watchdog);
103
acpi_watchdog_init(void)104 void __init acpi_watchdog_init(void)
105 {
106 const struct acpi_wdat_entry *entries;
107 const struct acpi_table_wdat *wdat;
108 struct list_head resource_list;
109 struct resource_entry *rentry;
110 struct platform_device *pdev;
111 struct resource *resources;
112 size_t nresources = 0;
113 int i;
114
115 wdat = acpi_watchdog_get_wdat();
116 if (!wdat) {
117 /* It is fine if there is no WDAT */
118 return;
119 }
120
121 /* Watchdog disabled by BIOS */
122 if (!(wdat->flags & ACPI_WDAT_ENABLED))
123 return;
124
125 /* Skip legacy PCI WDT devices */
126 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
127 wdat->pci_device != 0xff || wdat->pci_function != 0xff)
128 return;
129
130 INIT_LIST_HEAD(&resource_list);
131
132 entries = (struct acpi_wdat_entry *)(wdat + 1);
133 for (i = 0; i < wdat->entries; i++) {
134 const struct acpi_generic_address *gas;
135 struct resource_entry *rentry;
136 struct resource res = {};
137 bool found;
138
139 gas = &entries[i].register_region;
140
141 res.start = gas->address;
142 res.end = res.start + ACPI_ACCESS_BYTE_WIDTH(gas->access_width) - 1;
143 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
144 res.flags = IORESOURCE_MEM;
145 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
146 res.flags = IORESOURCE_IO;
147 } else {
148 pr_warn("Unsupported address space: %u\n",
149 gas->space_id);
150 goto fail_free_resource_list;
151 }
152
153 found = false;
154 resource_list_for_each_entry(rentry, &resource_list) {
155 if (rentry->res->flags == res.flags &&
156 resource_overlaps(rentry->res, &res)) {
157 if (res.start < rentry->res->start)
158 rentry->res->start = res.start;
159 if (res.end > rentry->res->end)
160 rentry->res->end = res.end;
161 found = true;
162 break;
163 }
164 }
165
166 if (!found) {
167 rentry = resource_list_create_entry(NULL, 0);
168 if (!rentry)
169 goto fail_free_resource_list;
170
171 *rentry->res = res;
172 resource_list_add_tail(rentry, &resource_list);
173 nresources++;
174 }
175 }
176
177 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
178 if (!resources)
179 goto fail_free_resource_list;
180
181 i = 0;
182 resource_list_for_each_entry(rentry, &resource_list)
183 resources[i++] = *rentry->res;
184
185 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
186 resources, nresources);
187 if (IS_ERR(pdev))
188 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev));
189
190 kfree(resources);
191
192 fail_free_resource_list:
193 resource_list_free(&resource_list);
194 }
195