v4.19.13 snapshot.
diff --git a/drivers/acpi/acpi_watchdog.c b/drivers/acpi/acpi_watchdog.c
new file mode 100644
index 0000000..9560030
--- /dev/null
+++ b/drivers/acpi/acpi_watchdog.c
@@ -0,0 +1,185 @@
+/*
+ * ACPI watchdog table parsing support.
+ *
+ * Copyright (C) 2016, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#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 const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
+{
+ const struct acpi_table_wdat *wdat = NULL;
+ acpi_status status;
+
+ if (acpi_disabled)
+ 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)) {
+ 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);
+
+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))
+ return;
+
+ /* Skip legacy PCI WDT devices */
+ if (wdat->pci_segment != 0xff || wdat->pci_bus != 0xff ||
+ wdat->pci_device != 0xff || wdat->pci_function != 0xff)
+ return;
+
+ 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;
+ if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+ res.flags = IORESOURCE_MEM;
+ res.end = res.start + ALIGN(gas->access_width, 4) - 1;
+ } else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
+ res.flags = IORESOURCE_IO;
+ res.end = res.start + gas->access_width - 1;
+ } 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_overlaps(rentry->res, &res)) {
+ if (res.start < rentry->res->start)
+ rentry->res->start = res.start;
+ if (res.end > rentry->res->end)
+ rentry->res->end = res.end;
+ 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);
+}