1 files changed, 45 insertions, 27 deletions

diff --git a/drivers/acpi/acpi_watchdog.c b/drivers/acpi/acpi_watchdog.c
index 4bde16fb97d88..95600309ce420 100644
--- a/drivers/acpi/acpi_watchdog.c
+++ b/drivers/acpi/acpi_watchdog.c
@@ -12,35 +12,51 @@
 #define pr_fmt(fmt) "ACPI: watchdog: " fmt
 
 #include <linux/acpi.h>
-#include <linux/dmi.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
 
 #include "internal.h"
 
-static const struct dmi_system_id acpi_watchdog_skip[] = {
-	{
-		/*
-		 * On Lenovo Z50-70 there are two issues with the WDAT
-		 * table. First some of the instructions use RTC SRAM
-		 * to store persistent information. This does not work well
-		 * with Linux RTC driver. Second, more important thing is
-		 * that the instructions do not actually reset the system.
-		 *
-		 * On this particular system iTCO_wdt seems to work just
-		 * fine so we prefer that over WDAT for now.
-		 *
-		 * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033.
-		 */
-		.ident = "Lenovo Z50-70",
-		.matches = {
-			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
-			DMI_MATCH(DMI_PRODUCT_NAME, "20354"),
-			DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo Z50-70"),
-		},
-	},
-	{}
-};
+#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)
 {
@@ -50,9 +66,6 @@ static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
 	if (acpi_disabled)
 		return NULL;
 
-	if (dmi_check_system(acpi_watchdog_skip))
-		return NULL;
-
 	status = acpi_get_table(ACPI_SIG_WDAT, 0,
 				(struct acpi_table_header **)&wdat);
 	if (ACPI_FAILURE(status)) {
@@ -60,6 +73,11 @@ static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
 		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;
 }