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 /**
  21  * Returns true if this system should prefer ACPI based watchdog instead of
  22  * the native one (which are typically the same hardware).
  23  */
  24 bool acpi_has_watchdog(void)
  25 {
  26         struct acpi_table_header hdr;
  27
  28         if (acpi_disabled)
  29                 return false;
  30
  31         return ACPI_SUCCESS(acpi_get_table_header(ACPI_SIG_WDAT, 0, &hdr));
  32 }
  33 EXPORT_SYMBOL_GPL(acpi_has_watchdog);
  34
  35 void __init acpi_watchdog_init(void)
  36 {
  37         const struct acpi_wdat_entry *entries;
  38         const struct acpi_table_wdat *wdat;
  39         struct list_head resource_list;
  40         struct resource_entry *rentry;
  41         struct platform_device *pdev;
  42         struct resource *resources;
  43         size_t nresources = 0;
  44         acpi_status status;
  45         int i;
  46
  47         status = acpi_get_table(ACPI_SIG_WDAT, 0,
  48                                 (struct acpi_table_header **)&wdat);
  49         if (ACPI_FAILURE(status)) {
  50                 /* It is fine if there is no WDAT */
  51                 return;
  52         }
  53
  54         /* Watchdog disabled by BIOS */
  55         if (!(wdat->flags & ACPI_WDAT_ENABLED))
  56                 return;
  57
  58         /* Skip legacy PCI WDT devices */
  59         if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
  60             wdat->pci_device != 0xff || wdat->pci_function != 0xff)
  61                 return;
  62
  63         INIT_LIST_HEAD(&resource_list);
  64
  65         entries = (struct acpi_wdat_entry *)(wdat + 1);
  66         for (i = 0; i < wdat->entries; i++) {
  67                 const struct acpi_generic_address *gas;
  68                 struct resource_entry *rentry;
  69                 struct resource res;
  70                 bool found;
  71
  72                 gas = &entries[i].register_region;
  73
  74                 res.start = gas->address;
  75                 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
  76                         res.flags = IORESOURCE_MEM;
  77                         res.end = res.start + ALIGN(gas->access_width, 4);
  78                 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
  79                         res.flags = IORESOURCE_IO;
  80                         res.end = res.start + gas->access_width;
  81                 } else {
  82                         pr_warn("Unsupported address space: %u\n",
  83                                 gas->space_id);
  84                         goto fail_free_resource_list;
  85                 }
  86
  87                 found = false;
  88                 resource_list_for_each_entry(rentry, &resource_list) {
  89                         if (rentry->res->flags == res.flags &&
  90                             resource_overlaps(rentry->res, &res)) {
  91                                 if (res.start < rentry->res->start)
  92                                         rentry->res->start = res.start;
  93                                 if (res.end > rentry->res->end)
  94                                         rentry->res->end = res.end;
  95                                 found = true;
  96                                 break;
  97                         }
  98                 }
  99
 100                 if (!found) {
 101                         rentry = resource_list_create_entry(NULL, 0);
 102                         if (!rentry)
 103                                 goto fail_free_resource_list;
 104
 105                         *rentry->res = res;
 106                         resource_list_add_tail(rentry, &resource_list);
 107                         nresources++;
 108                 }
 109         }
 110
 111         resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);
 112         if (!resources)
 113                 goto fail_free_resource_list;
 114
 115         i = 0;
 116         resource_list_for_each_entry(rentry, &resource_list)
 117                 resources[i++] = *rentry->res;
 118
 119         pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,
 120                                                resources, nresources);
 121         if (IS_ERR(pdev))
 122                 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev));
 123
 124         kfree(resources);
 125
 126 fail_free_resource_list:
 127         resource_list_free(&resource_list);
 128 }