[PATCH 6.19 391/844] fix it87_wdt early reboot by reporting running timer

[Sasha Levin]

From: René Rebe <rene@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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