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 const struct acpi_table_wdat *acpi_watchdog_get_wdat(void) 62 { 63 const struct acpi_table_wdat *wdat = NULL; 64 acpi_status status; 65 66 if (acpi_disabled) 67 return NULL; 68 69 status = acpi_get_table(ACPI_SIG_WDAT, 0, 70 (struct acpi_table_header **)&wdat); 71 if (ACPI_FAILURE(status)) { 72 /* It is fine if there is no WDAT */ 73 return NULL; 74 } 75 76 if (acpi_watchdog_uses_rtc(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 void __init acpi_watchdog_init(void) 95 { 96 const struct acpi_wdat_entry *entries; 97 const struct acpi_table_wdat *wdat; 98 struct list_head resource_list; 99 struct resource_entry *rentry; 100 struct platform_device *pdev; 101 struct resource *resources; 102 size_t nresources = 0; 103 int i; 104 105 wdat = acpi_watchdog_get_wdat(); 106 if (!wdat) { 107 /* It is fine if there is no WDAT */ 108 return; 109 } 110 111 /* Watchdog disabled by BIOS */ 112 if (!(wdat->flags & ACPI_WDAT_ENABLED)) 113 return; 114 115 /* Skip legacy PCI WDT devices */ 116 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff || 117 wdat->pci_device != 0xff || wdat->pci_function != 0xff) 118 return; 119 120 INIT_LIST_HEAD(&resource_list); 121 122 entries = (struct acpi_wdat_entry *)(wdat + 1); 123 for (i = 0; i < wdat->entries; i++) { 124 const struct acpi_generic_address *gas; 125 struct resource_entry *rentry; 126 struct resource res = {}; 127 bool found; 128 129 gas = &entries[i].register_region; 130 131 res.start = gas->address; 132 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { 133 res.flags = IORESOURCE_MEM; 134 res.end = res.start + ALIGN(gas->access_width, 4) - 1; 135 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { 136 res.flags = IORESOURCE_IO; 137 res.end = res.start + gas->access_width - 1; 138 } else { 139 pr_warn("Unsupported address space: %u\n", 140 gas->space_id); 141 goto fail_free_resource_list; 142 } 143 144 found = false; 145 resource_list_for_each_entry(rentry, &resource_list) { 146 if (rentry->res->flags == res.flags && 147 resource_overlaps(rentry->res, &res)) { 148 if (res.start < rentry->res->start) 149 rentry->res->start = res.start; 150 if (res.end > rentry->res->end) 151 rentry->res->end = res.end; 152 found = true; 153 break; 154 } 155 } 156 157 if (!found) { 158 rentry = resource_list_create_entry(NULL, 0); 159 if (!rentry) 160 goto fail_free_resource_list; 161 162 *rentry->res = res; 163 resource_list_add_tail(rentry, &resource_list); 164 nresources++; 165 } 166 } 167 168 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL); 169 if (!resources) 170 goto fail_free_resource_list; 171 172 i = 0; 173 resource_list_for_each_entry(rentry, &resource_list) 174 resources[i++] = *rentry->res; 175 176 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE, 177 resources, nresources); 178 if (IS_ERR(pdev)) 179 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev)); 180 181 kfree(resources); 182 183 fail_free_resource_list: 184 resource_list_free(&resource_list); 185 } 186