diff options
Diffstat (limited to 'drivers/acpi/acpi_watchdog.c')
| -rw-r--r-- | drivers/acpi/acpi_watchdog.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/drivers/acpi/acpi_watchdog.c b/drivers/acpi/acpi_watchdog.c new file mode 100644 index 0000000000..ca28183f4d --- /dev/null +++ b/drivers/acpi/acpi_watchdog.c @@ -0,0 +1,190 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ACPI watchdog table parsing support. + * + * Copyright (C) 2016, Intel Corporation + * Author: Mika Westerberg <mika.westerberg@linux.intel.com> + */ + +#define pr_fmt(fmt) "ACPI: watchdog: " fmt + +#include <linux/acpi.h> +#include <linux/ioport.h> +#include <linux/platform_device.h> + +#include "internal.h" + +#ifdef CONFIG_RTC_MC146818_LIB +#include <linux/mc146818rtc.h> + +/* + * There are several systems where the WDAT table is accessing RTC SRAM to + * store persistent information. This does not work well with the Linux RTC + * driver so on those systems we skip WDAT driver and prefer iTCO_wdt + * instead. + * + * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033. + */ +static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat) +{ + const struct acpi_wdat_entry *entries; + int i; + + entries = (struct acpi_wdat_entry *)(wdat + 1); + for (i = 0; i < wdat->entries; i++) { + const struct acpi_generic_address *gas; + + gas = &entries[i].register_region; + if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { + switch (gas->address) { + case RTC_PORT(0): + case RTC_PORT(1): + case RTC_PORT(2): + case RTC_PORT(3): + return true; + } + } + } + + return false; +} +#else +static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat) +{ + return false; +} +#endif + +static bool acpi_no_watchdog; + +static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void) +{ + const struct acpi_table_wdat *wdat = NULL; + acpi_status status; + + if (acpi_disabled || acpi_no_watchdog) + return NULL; + + status = acpi_get_table(ACPI_SIG_WDAT, 0, + (struct acpi_table_header **)&wdat); + if (ACPI_FAILURE(status)) { + /* It is fine if there is no WDAT */ + return NULL; + } + + if (acpi_watchdog_uses_rtc(wdat)) { + acpi_put_table((struct acpi_table_header *)wdat); + pr_info("Skipping WDAT on this system because it uses RTC SRAM\n"); + return NULL; + } + + return wdat; +} + +/** + * Returns true if this system should prefer ACPI based watchdog instead of + * the native one (which are typically the same hardware). + */ +bool acpi_has_watchdog(void) +{ + return !!acpi_watchdog_get_wdat(); +} +EXPORT_SYMBOL_GPL(acpi_has_watchdog); + +/* ACPI watchdog can be disabled on boot command line */ +static int __init disable_acpi_watchdog(char *str) +{ + acpi_no_watchdog = true; + return 1; +} +__setup("acpi_no_watchdog", disable_acpi_watchdog); + +void __init acpi_watchdog_init(void) +{ + const struct acpi_wdat_entry *entries; + const struct acpi_table_wdat *wdat; + struct list_head resource_list; + struct resource_entry *rentry; + struct platform_device *pdev; + struct resource *resources; + size_t nresources = 0; + int i; + + wdat = acpi_watchdog_get_wdat(); + if (!wdat) { + /* It is fine if there is no WDAT */ + return; + } + + /* Watchdog disabled by BIOS */ + if (!(wdat->flags & ACPI_WDAT_ENABLED)) + goto fail_put_wdat; + + /* Skip legacy PCI WDT devices */ + if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff || + wdat->pci_device != 0xff || wdat->pci_function != 0xff) + goto fail_put_wdat; + + INIT_LIST_HEAD(&resource_list); + + entries = (struct acpi_wdat_entry *)(wdat + 1); + for (i = 0; i < wdat->entries; i++) { + const struct acpi_generic_address *gas; + struct resource_entry *rentry; + struct resource res = {}; + bool found; + + gas = &entries[i].register_region; + + res.start = gas->address; + res.end = res.start + ACPI_ACCESS_BYTE_WIDTH(gas->access_width) - 1; + if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { + res.flags = IORESOURCE_MEM; + } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { + res.flags = IORESOURCE_IO; + } else { + pr_warn("Unsupported address space: %u\n", + gas->space_id); + goto fail_free_resource_list; + } + + found = false; + resource_list_for_each_entry(rentry, &resource_list) { + if (rentry->res->flags == res.flags && + resource_union(rentry->res, &res, rentry->res)) { + found = true; + break; + } + } + + if (!found) { + rentry = resource_list_create_entry(NULL, 0); + if (!rentry) + goto fail_free_resource_list; + + *rentry->res = res; + resource_list_add_tail(rentry, &resource_list); + nresources++; + } + } + + resources = kcalloc(nresources, sizeof(*resources), GFP_KERNEL); + if (!resources) + goto fail_free_resource_list; + + i = 0; + resource_list_for_each_entry(rentry, &resource_list) + resources[i++] = *rentry->res; + + pdev = platform_device_register_simple("wdat_wdt", PLATFORM_DEVID_NONE, + resources, nresources); + if (IS_ERR(pdev)) + pr_err("Device creation failed: %ld\n", PTR_ERR(pdev)); + + kfree(resources); + +fail_free_resource_list: + resource_list_free(&resource_list); +fail_put_wdat: + acpi_put_table((struct acpi_table_header *)wdat); +} |