[PATCH 5.5 09/65] ACPI: watchdog: Allow disabling WDAT at boot

From: Greg Kroah-Hartman
Date: Thu Mar 19 2020 - 09:25:12 EST


From: Jean Delvare <jdelvare@xxxxxxx>

[ Upstream commit 3f9e12e0df012c4a9a7fd7eb0d3ae69b459d6b2c ]

In case the WDAT interface is broken, give the user an option to
ignore it to let a native driver bind to the watchdog device instead.

Signed-off-by: Jean Delvare <jdelvare@xxxxxxx>
Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 4 ++++
drivers/acpi/acpi_watchdog.c | 12 +++++++++++-
2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ade4e6ec23e03..727a03fb26c99 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -136,6 +136,10 @@
dynamic table installation which will install SSDT
tables to /sys/firmware/acpi/tables/dynamic.

+ acpi_no_watchdog [HW,ACPI,WDT]
+ Ignore the ACPI-based watchdog interface (WDAT) and let
+ a native driver control the watchdog device instead.
+
acpi_rsdp= [ACPI,EFI,KEXEC]
Pass the RSDP address to the kernel, mostly used
on machines running EFI runtime service to boot the
diff --git a/drivers/acpi/acpi_watchdog.c b/drivers/acpi/acpi_watchdog.c
index d827a4a3e9460..6e9ec6e3fe47d 100644
--- a/drivers/acpi/acpi_watchdog.c
+++ b/drivers/acpi/acpi_watchdog.c
@@ -55,12 +55,14 @@ static bool acpi_watchdog_uses_rtc(const struct acpi_table_wdat *wdat)
}
#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)
+ if (acpi_disabled || acpi_no_watchdog)
return NULL;

status = acpi_get_table(ACPI_SIG_WDAT, 0,
@@ -88,6 +90,14 @@ bool acpi_has_watchdog(void)
}
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;
--
2.20.1