drivers/acpi/acpi_watchdog.c

   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  */
  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
  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
  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  */
  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 */
  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
 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 (resource_contains(rentry->res, &res)) {
 156                                 found = true;
 157                                 break;
 158                         }
 159                 }
 160
 161                 if (!found) {
 162                         rentry = resource_list_create_entry(NULL, 0);
 163                         if (!rentry)
 164                                 goto fail_free_resource_list;
 165
 166                         *rentry->res = res;
 167                         resource_list_add_tail(rentry, &resource_list);
 168                         nresources++;
 169                 }
 170         }
 171
 172         resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
 173         if (!resources)
 174                 goto fail_free_resource_list;
 175
 176         i = 0;
 177         resource_list_for_each_entry(rentry, &resource_list)
 178                 resources[i++] = *rentry->res;
 179
 180         pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
 181                                                resources, nresources);
 182         if (IS_ERR(pdev))
 183                 pr_err("Failed to create platform device\n");
 184
 185         kfree(resources);
 186
 187 fail_free_resource_list:
 188         resource_list_free(&resource_list);
 189 }