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/dmi.h> 16 #include <linux/ioport.h> 17 #include <linux/platform_device.h> 18 19 #include "internal.h" 20 21 static const struct dmi_system_id acpi_watchdog_skip[] = { 22 { 23 /* 24 * On Lenovo Z50-70 there are two issues with the WDAT 25 * table. First some of the instructions use RTC SRAM 26 * to store persistent information. This does not work well 27 * with Linux RTC driver. Second, more important thing is 28 * that the instructions do not actually reset the system. 29 * 30 * On this particular system iTCO_wdt seems to work just 31 * fine so we prefer that over WDAT for now. 32 * 33 * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033. 34 */ 35 .ident = "Lenovo Z50-70", 36 .matches = { 37 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"), 38 DMI_MATCH(DMI_PRODUCT_NAME, "20354"), 39 DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo Z50-70"), 40 }, 41 }, 42 {} 43 }; 44 45 static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void) 46 { 47 const struct acpi_table_wdat *wdat = NULL; 48 acpi_status status; 49 50 if (acpi_disabled) 51 return NULL; 52 53 if (dmi_check_system(acpi_watchdog_skip)) 54 return NULL; 55 56 status = acpi_get_table(ACPI_SIG_WDAT, 0, 57 (struct acpi_table_header **)&wdat); 58 if (ACPI_FAILURE(status)) { 59 /* It is fine if there is no WDAT */ 60 return NULL; 61 } 62 63 return wdat; 64 } 65 66 /** 67 * Returns true if this system should prefer ACPI based watchdog instead of 68 * the native one (which are typically the same hardware). 69 */ 70 bool acpi_has_watchdog(void) 71 { 72 return !!acpi_watchdog_get_wdat(); 73 } 74 EXPORT_SYMBOL_GPL(acpi_has_watchdog); 75 76 void __init acpi_watchdog_init(void) 77 { 78 const struct acpi_wdat_entry *entries; 79 const struct acpi_table_wdat *wdat; 80 struct list_head resource_list; 81 struct resource_entry *rentry; 82 struct platform_device *pdev; 83 struct resource *resources; 84 size_t nresources = 0; 85 int i; 86 87 wdat = acpi_watchdog_get_wdat(); 88 if (!wdat) { 89 /* It is fine if there is no WDAT */ 90 return; 91 } 92 93 /* Watchdog disabled by BIOS */ 94 if (!(wdat->flags & ACPI_WDAT_ENABLED)) 95 return; 96 97 /* Skip legacy PCI WDT devices */ 98 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff || 99 wdat->pci_device != 0xff || wdat->pci_function != 0xff) 100 return; 101 102 INIT_LIST_HEAD(&resource_list); 103 104 entries = (struct acpi_wdat_entry *)(wdat + 1); 105 for (i = 0; i < wdat->entries; i++) { 106 const struct acpi_generic_address *gas; 107 struct resource_entry *rentry; 108 struct resource res = {}; 109 bool found; 110 111 gas = &entries[i].register_region; 112 113 res.start = gas->address; 114 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { 115 res.flags = IORESOURCE_MEM; 116 res.end = res.start + ALIGN(gas->access_width, 4) - 1; 117 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { 118 res.flags = IORESOURCE_IO; 119 res.end = res.start + gas->access_width - 1; 120 } else { 121 pr_warn("Unsupported address space: %u\n", 122 gas->space_id); 123 goto fail_free_resource_list; 124 } 125 126 found = false; 127 resource_list_for_each_entry(rentry, &resource_list) { 128 if (rentry->res->flags == res.flags && 129 resource_overlaps(rentry->res, &res)) { 130 if (res.start < rentry->res->start) 131 rentry->res->start = res.start; 132 if (res.end > rentry->res->end) 133 rentry->res->end = res.end; 134 found = true; 135 break; 136 } 137 } 138 139 if (!found) { 140 rentry = resource_list_create_entry(NULL, 0); 141 if (!rentry) 142 goto fail_free_resource_list; 143 144 *rentry->res = res; 145 resource_list_add_tail(rentry, &resource_list); 146 nresources++; 147 } 148 } 149 150 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL); 151 if (!resources) 152 goto fail_free_resource_list; 153 154 i = 0; 155 resource_list_for_each_entry(rentry, &resource_list) 156 resources[i++] = *rentry->res; 157 158 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE, 159 resources, nresources); 160 if (IS_ERR(pdev)) 161 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev)); 162 163 kfree(resources); 164 165 fail_free_resource_list: 166 resource_list_free(&resource_list); 167 } 168