[PATCH AUTOSEL 5.15 29/35] watchdog: it87_wdt: Keep WDTCTRL bit 3 unmodified for IT8784/IT8786

Sasha Levin
2024-01-22T15:14:35Z

From: Werner Fischer <devlists@wefi.net>

[ Upstream commit d12971849d71781c1e4ffd1117d4878ce233d319 ]

WDTCTRL bit 3 sets the mode choice for the clock input of IT8784/IT8786.
Some motherboards require this bit to be set to 1 (= PCICLK mode),
otherwise the watchdog functionality gets broken. The BIOS of those
motherboards sets WDTCTRL bit 3 already to 1.

Instead of setting all bits of WDTCTRL to 0 by writing 0x00 to it, keep
bit 3 of it unchanged for IT8784/IT8786 chips. In this way, bit 3 keeps
the status as set by the BIOS of the motherboard.

Watchdog tests have been successful with this patch with the following
systems:
IT8784: Thomas-Krenn LES plus v2 (YANLING YL-KBRL2 V2)
IT8786: Thomas-Krenn LES plus v3 (YANLING YL-CLU L2)
IT8786: Thomas-Krenn LES network 6L v2 (YANLING YL-CLU6L)

Link: https://lore.kernel.org/all/140b264d-341f-465b-8715-dacfe84b3f71@roeck-us.net/

Signed-off-by: Werner Fischer <devlists@wefi.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20231213094525.11849-4-devlists@wefi.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 | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/it87_wdt.c b/drivers/watchdog/it87_wdt.c
index bb1122909396..843f9f8e3917 100644
--- a/drivers/watchdog/it87_wdt.c
+++ b/drivers/watchdog/it87_wdt.c
@@ -255,6 +255,7 @@ static struct watchdog_device wdt_dev = {
static int __init it87_wdt_init(void)
{
u8 chip_rev;
+ u8 ctrl;
int rc;

rc = superio_enter();
@@ -313,7 +314,18 @@ static int __init it87_wdt_init(void)

superio_select(GPIO);
superio_outb(WDT_TOV1, WDTCFG);
- superio_outb(0x00, WDTCTRL);
+
+ switch (chip_type) {
+ case IT8784_ID:
+ case IT8786_ID:
+ ctrl = superio_inb(WDTCTRL);
+ ctrl &= 0x08;
+ superio_outb(ctrl, WDTCTRL);
+ break;
+ default:
+ superio_outb(0x00, WDTCTRL);
+ }
+
superio_exit();

if (timeout < 1 || timeout > max_units * 60) {
--
2.43.0