[PATCH] watchdog: iTCO_wdt: Set NO_REBOOT if the watchdog is not already running

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Daniel reported that the commit 1ae3e78c0820 ("watchdog: iTCO_wdt: No
need to stop the timer in probe") makes QEMU implementation of the iTCO
watchdog not to trigger reboot anymore when NO_REBOOT flag is initially
cleared using this option (in QEMU command line):

  -global ICH9-LPC.noreboot=false

The problem with the commit is that it left the unconditional setting of
NO_REBOOT that is not cleared anymore when the kernel keeps pinging the
watchdog (as opposed to the previous code that called iTCO_wdt_stop()
that cleared it).

Fix this so that we only set NO_REBOOT if the watchdog was not initially
running.

Fixes: 1ae3e78c0820 ("watchdog: iTCO_wdt: No need to stop the timer in probe")
Reported-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
Hi,

I tested this with the command line Daniel provided:

      -watchdog-action poweroff \
      -global ICH9-LPC.noreboot=false

With the patch QEMU shuts down after ~60s and without it keeps running.

 drivers/watchdog/iTCO_wdt.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index 34693f11385f..e937b4dd28be 100644
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -423,14 +423,18 @@ static unsigned int iTCO_wdt_get_timeleft(struct watchdog_device *wd_dev)
 	return time_left;
 }
 
-static void iTCO_wdt_set_running(struct iTCO_wdt_private *p)
+/* Returns true if the watchdog was running */
+static bool iTCO_wdt_set_running(struct iTCO_wdt_private *p)
 {
 	u16 val;
 
-	/* Bit 11: TCO Timer Halt -> 0 = The TCO timer is * enabled */
+	/* Bit 11: TCO Timer Halt -> 0 = The TCO timer is enabled */
 	val = inw(TCO1_CNT(p));
-	if (!(val & BIT(11)))
+	if (!(val & BIT(11))) {
 		set_bit(WDOG_HW_RUNNING, &p->wddev.status);
+		return true;
+	}
+	return false;
 }
 
 /*
@@ -518,9 +522,6 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
 		return -ENODEV;	/* Cannot reset NO_REBOOT bit */
 	}
 
-	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
-	p->update_no_reboot_bit(p->no_reboot_priv, true);
-
 	if (turn_SMI_watchdog_clear_off >= p->iTCO_version) {
 		/*
 		 * Bit 13: TCO_EN -> 0
@@ -572,7 +573,13 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
 	watchdog_set_drvdata(&p->wddev, p);
 	platform_set_drvdata(pdev, p);
 
-	iTCO_wdt_set_running(p);
+	if (!iTCO_wdt_set_running(p)) {
+		/*
+		 * If the watchdog was not running set NO_REBOOT now to
+		 * prevent later reboots.
+		 */
+		p->update_no_reboot_bit(p->no_reboot_priv, true);
+	}
 
 	/* Check that the heartbeat value is within it's range;
 	   if not reset to the default */
-- 
2.35.1