drivers/acpi/acpi_watchdog.c

   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, 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  */
  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(&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 }