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 const struct acpi_table_wdat *acpi_watchdog_get_wdat(void) 59 { 60 const struct acpi_table_wdat *wdat = NULL; 61 acpi_status status; 62 63 if (acpi_disabled) 64 return NULL; 65 66 status = acpi_get_table(ACPI_SIG_WDAT, 0, 67 (struct acpi_table_header **)&wdat); 68 if (ACPI_FAILURE(status)) { 69 /* It is fine if there is no WDAT */ 70 return NULL; 71 } 72 73 if (acpi_watchdog_uses_rtc(wdat)) { 74 pr_info("Skipping WDAT on this system because it uses RTC SRAM\n"); 75 return NULL; 76 } 77 78 return wdat; 79 } 80 81 /** 82 * Returns true if this system should prefer ACPI based watchdog instead of 83 * the native one (which are typically the same hardware). 84 */ 85 bool acpi_has_watchdog(void) 86 { 87 return !!acpi_watchdog_get_wdat(); 88 } 89 EXPORT_SYMBOL_GPL(acpi_has_watchdog); 90 91 void __init acpi_watchdog_init(void) 92 { 93 const struct acpi_wdat_entry *entries; 94 const struct acpi_table_wdat *wdat; 95 struct list_head resource_list; 96 struct resource_entry *rentry; 97 struct platform_device *pdev; 98 struct resource *resources; 99 size_t nresources = 0; 100 int i; 101 102 wdat = acpi_watchdog_get_wdat(); 103 if (!wdat) { 104 /* It is fine if there is no WDAT */ 105 return; 106 } 107 108 /* Watchdog disabled by BIOS */ 109 if (!(wdat->flags & ACPI_WDAT_ENABLED)) 110 return; 111 112 /* Skip legacy PCI WDT devices */ 113 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff || 114 wdat->pci_device != 0xff || wdat->pci_function != 0xff) 115 return; 116 117 INIT_LIST_HEAD(&resource_list); 118 119 entries = (struct acpi_wdat_entry *)(wdat + 1); 120 for (i = 0; i < wdat->entries; i++) { 121 const struct acpi_generic_address *gas; 122 struct resource_entry *rentry; 123 struct resource res = {}; 124 bool found; 125 126 gas = &entries[i].register_region; 127 128 res.start = gas->address; 129 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { 130 res.flags = IORESOURCE_MEM; 131 res.end = res.start + ALIGN(gas->access_width, 4) - 1; 132 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { 133 res.flags = IORESOURCE_IO; 134 res.end = res.start + gas->access_width - 1; 135 } else { 136 pr_warn("Unsupported address space: %u\n", 137 gas->space_id); 138 goto fail_free_resource_list; 139 } 140 141 found = false; 142 resource_list_for_each_entry(rentry, &resource_list) { 143 if (rentry->res->flags == res.flags && 144 resource_overlaps(rentry->res, &res)) { 145 if (res.start < rentry->res->start) 146 rentry->res->start = res.start; 147 if (res.end > rentry->res->end) 148 rentry->res->end = res.end; 149 found = true; 150 break; 151 } 152 } 153 154 if (!found) { 155 rentry = resource_list_create_entry(NULL, 0); 156 if (!rentry) 157 goto fail_free_resource_list; 158 159 *rentry->res = res; 160 resource_list_add_tail(rentry, &resource_list); 161 nresources++; 162 } 163 } 164 165 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL); 166 if (!resources) 167 goto fail_free_resource_list; 168 169 i = 0; 170 resource_list_for_each_entry(rentry, &resource_list) 171 resources[i++] = *rentry->res; 172 173 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE, 174 resources, nresources); 175 if (IS_ERR(pdev)) 176 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev)); 177 178 kfree(resources); 179 180 fail_free_resource_list: 181 resource_list_free(&resource_list); 182 } 183