[PATCH 6.18 347/752] fix it87_wdt early reboot by reporting running timer

Sasha Levin
2026-02-28T17:52:59Z

From: René Rebe <rene@exactco.de>

[ Upstream commit 88b2ab346436f799b99894a3e9518a3ffa344524 ]

Some products, such as the Ugreen DXP4800 Plus NAS, ship with the it87
wdt enabled by the firmware and a broken BIOS option that does not
allow to change the time or turn it off. As this makes installing
Linux rather difficult, change the it87_wdt to report it running to
the watchdog core.

Signed-off-by: René Rebe <rene@exactco.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/watchdog/it87_wdt.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/watchdog/it87_wdt.c b/drivers/watchdog/it87_wdt.c
index 3b8488c86a2f3..1d9f8591f38d8 100644
--- a/drivers/watchdog/it87_wdt.c
+++ b/drivers/watchdog/it87_wdt.c
@@ -188,6 +188,12 @@ static void _wdt_update_timeout(unsigned int t)
superio_outb(t >> 8, WDTVALMSB);
}

+/* Internal function, should be called after superio_select(GPIO) */
+static bool _wdt_running(void)
+{
+ return superio_inb(WDTVALLSB) || (max_units > 255 && superio_inb(WDTVALMSB));
+}
+
static int wdt_update_timeout(unsigned int t)
{
int ret;
@@ -374,6 +380,12 @@ static int __init it87_wdt_init(void)
}
}

+ /* wdt already left running by firmware? */
+ if (_wdt_running()) {
+ pr_info("Left running by firmware.\n");
+ set_bit(WDOG_HW_RUNNING, &wdt_dev.status);
+ }
+
superio_exit();

if (timeout < 1 || timeout > max_units * 60) {
--
2.51.0