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 | */ |
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 |
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 | |
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, instance: 0, |
69 | out_table: (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(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 | */ |
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 */ |
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 | |
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(list: &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(r1: rentry->res, r2: &res, r: rentry->res)) { |
155 | found = true; |
156 | break; |
157 | } |
158 | } |
159 | |
160 | if (!found) { |
161 | rentry = resource_list_create_entry(NULL, extra_size: 0); |
162 | if (!rentry) |
163 | goto fail_free_resource_list; |
164 | |
165 | *rentry->res = res; |
166 | resource_list_add_tail(entry: rentry, head: &resource_list); |
167 | nresources++; |
168 | } |
169 | } |
170 | |
171 | resources = kcalloc(n: nresources, size: 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(name: "wdat_wdt" , PLATFORM_DEVID_NONE, |
180 | res: resources, num: nresources); |
181 | if (IS_ERR(ptr: pdev)) |
182 | pr_err("Device creation failed: %pe\n" , pdev); |
183 | |
184 | kfree(objp: resources); |
185 | |
186 | fail_free_resource_list: |
187 | resource_list_free(head: &resource_list); |
188 | fail_put_wdat: |
189 | acpi_put_table(table: (struct acpi_table_header *)wdat); |
190 | } |
191 | |