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 bool acpi_no_watchdog; 59 60 static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void) 61 { 62 const struct acpi_table_wdat *wdat = NULL; 63 acpi_status status; 64 65 if (acpi_disabled || acpi_no_watchdog) 66 return NULL; 67 68 status = acpi_get_table(ACPI_SIG_WDAT, 0, 69 (struct acpi_table_header **)&wdat); 70 if (ACPI_FAILURE(status)) { 71 /* It is fine if there is no WDAT */ 72 return NULL; 73 } 74 75 if (acpi_watchdog_uses_rtc(wdat)) { 76 pr_info("Skipping WDAT on this system because it uses RTC SRAM\n"); 77 return NULL; 78 } 79 80 return wdat; 81 } 82 83 /** 84 * Returns true if this system should prefer ACPI based watchdog instead of 85 * the native one (which are typically the same hardware). 86 */ 87 bool acpi_has_watchdog(void) 88 { 89 return !!acpi_watchdog_get_wdat(); 90 } 91 EXPORT_SYMBOL_GPL(acpi_has_watchdog); 92 93 /* ACPI watchdog can be disabled on boot command line */ 94 static int __init disable_acpi_watchdog(char *str) 95 { 96 acpi_no_watchdog = true; 97 return 1; 98 } 99 __setup("acpi_no_watchdog", disable_acpi_watchdog); 100 101 void __init acpi_watchdog_init(void) 102 { 103 const struct acpi_wdat_entry *entries; 104 const struct acpi_table_wdat *wdat; 105 struct list_head resource_list; 106 struct resource_entry *rentry; 107 struct platform_device *pdev; 108 struct resource *resources; 109 size_t nresources = 0; 110 int i; 111 112 wdat = acpi_watchdog_get_wdat(); 113 if (!wdat) { 114 /* It is fine if there is no WDAT */ 115 return; 116 } 117 118 /* Watchdog disabled by BIOS */ 119 if (!(wdat->flags & ACPI_WDAT_ENABLED)) 120 return; 121 122 /* Skip legacy PCI WDT devices */ 123 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff || 124 wdat->pci_device != 0xff || wdat->pci_function != 0xff) 125 return; 126 127 INIT_LIST_HEAD(&resource_list); 128 129 entries = (struct acpi_wdat_entry *)(wdat + 1); 130 for (i = 0; i < wdat->entries; i++) { 131 const struct acpi_generic_address *gas; 132 struct resource_entry *rentry; 133 struct resource res = {}; 134 bool found; 135 136 gas = &entries[i].register_region; 137 138 res.start = gas->address; 139 res.end = res.start + ACPI_ACCESS_BYTE_WIDTH(gas->access_width) - 1; 140 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { 141 res.flags = IORESOURCE_MEM; 142 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { 143 res.flags = IORESOURCE_IO; 144 } else { 145 pr_warn("Unsupported address space: %u\n", 146 gas->space_id); 147 goto fail_free_resource_list; 148 } 149 150 found = false; 151 resource_list_for_each_entry(rentry, &resource_list) { 152 if (rentry->res->flags == res.flags && 153 resource_overlaps(rentry->res, &res)) { 154 if (res.start < rentry->res->start) 155 rentry->res->start = res.start; 156 if (res.end > rentry->res->end) 157 rentry->res->end = res.end; 158 found = true; 159 break; 160 } 161 } 162 163 if (!found) { 164 rentry = resource_list_create_entry(NULL, 0); 165 if (!rentry) 166 goto fail_free_resource_list; 167 168 *rentry->res = res; 169 resource_list_add_tail(rentry, &resource_list); 170 nresources++; 171 } 172 } 173 174 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL); 175 if (!resources) 176 goto fail_free_resource_list; 177 178 i = 0; 179 resource_list_for_each_entry(rentry, &resource_list) 180 resources[i++] = *rentry->res; 181 182 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE, 183 resources, nresources); 184 if (IS_ERR(pdev)) 185 pr_err("Device creation failed: %ld\n", PTR_ERR(pdev)); 186 187 kfree(resources); 188 189 fail_free_resource_list: 190 resource_list_free(&resource_list); 191 } 192