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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * ACPI watchdog table parsing support.4 *5 * Copyright (C) 2016, Intel Corporation6 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>7 */8 9#define pr_fmt(fmt) "ACPI: watchdog: " fmt10 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_LIB18#include <linux/mc146818rtc.h>19 20/*21 * There are several systems where the WDAT table is accessing RTC SRAM to22 * store persistent information. This does not work well with the Linux RTC23 * driver so on those systems we skip WDAT driver and prefer iTCO_wdt24 * instead.25 *26 * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033.27 */28static 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#else52static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)53{54 return false;55}56#endif57 58static bool acpi_no_watchdog;59 60static 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 acpi_put_table((struct acpi_table_header *)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 of86 * the native one (which are typically the same hardware).87 */88bool acpi_has_watchdog(void)89{90 return !!acpi_watchdog_get_wdat();91}92EXPORT_SYMBOL_GPL(acpi_has_watchdog);93 94/* ACPI watchdog can be disabled on boot command line */95static int __init disable_acpi_watchdog(char *str)96{97 acpi_no_watchdog = true;98 return 1;99}100__setup("acpi_no_watchdog", disable_acpi_watchdog);101 102void __init acpi_watchdog_init(void)103{104 const struct acpi_wdat_entry *entries;105 const struct acpi_table_wdat *wdat;106 struct list_head resource_list;107 struct resource_entry *rentry;108 struct platform_device *pdev;109 struct resource *resources;110 size_t nresources = 0;111 int i;112 113 wdat = acpi_watchdog_get_wdat();114 if (!wdat) {115 /* It is fine if there is no WDAT */116 return;117 }118 119 /* Watchdog disabled by BIOS */120 if (!(wdat->flags & ACPI_WDAT_ENABLED))121 goto fail_put_wdat;122 123 /* Skip legacy PCI WDT devices */124 if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||125 wdat->pci_device != 0xff || wdat->pci_function != 0xff)126 goto fail_put_wdat;127 128 INIT_LIST_HEAD(&resource_list);129 130 entries = (struct acpi_wdat_entry *)(wdat + 1);131 for (i = 0; i < wdat->entries; i++) {132 const struct acpi_generic_address *gas;133 struct resource_entry *rentry;134 struct resource res = {};135 bool found;136 137 gas = &entries[i].register_region;138 139 res.start = gas->address;140 res.end = res.start + ACPI_ACCESS_BYTE_WIDTH(gas->access_width) - 1;141 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {142 res.flags = IORESOURCE_MEM;143 } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {144 res.flags = IORESOURCE_IO;145 } else {146 pr_warn("Unsupported address space: %u\n",147 gas->space_id);148 goto fail_free_resource_list;149 }150 151 found = false;152 resource_list_for_each_entry(rentry, &resource_list) {153 if (rentry->res->flags == res.flags &&154 resource_union(rentry->res, &res, rentry->res)) {155 found = true;156 break;157 }158 }159 160 if (!found) {161 rentry = resource_list_create_entry(NULL, 0);162 if (!rentry)163 goto fail_free_resource_list;164 165 *rentry->res = res;166 resource_list_add_tail(rentry, &resource_list);167 nresources++;168 }169 }170 171 resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL);172 if (!resources)173 goto fail_free_resource_list;174 175 i = 0;176 resource_list_for_each_entry(rentry, &resource_list)177 resources[i++] = *rentry->res;178 179 pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE,180 resources, nresources);181 if (IS_ERR(pdev))182 pr_err("Device creation failed: %pe\n", pdev);183 184 kfree(resources);185 186fail_free_resource_list:187 resource_list_free(&resource_list);188fail_put_wdat:189 acpi_put_table((struct acpi_table_header *)wdat);190}191