Revert "watchdog: iTCO_wdt: Account for rebooting on second timeout"

This reverts commit cb011044e3 ("watchdog: iTCO_wdt: Account for
rebooting on second timeout") and commit aec42642d9 ("watchdog: iTCO_wdt:
Fix detection of SMI-off case") since those patches cause a regression
on certain boards (https://bugzilla.kernel.org/show_bug.cgi?id=213809).

While this revert may result in some boards to only reset after twice
the configured timeout value, that is still better than a watchdog reset
after half the configured value.

Fixes: cb011044e3 ("watchdog: iTCO_wdt: Account for rebooting on second timeout")
Fixes: aec42642d9 ("watchdog: iTCO_wdt: Fix detection of SMI-off case")
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Mantas Mikulėnas <grawity@gmail.com>
Reported-by: Javier S. Pedro <debbugs@javispedro.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211008003302.1461733-1-linux@roeck-us.net
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/iTCO_wdt.c

@@ -71,8 +71,6 @@
 #define TCOBASE(p)	((p)->tco_res->start)
 /* SMI Control and Enable Register */
 #define SMI_EN(p)	((p)->smi_res->start)
-#define TCO_EN		(1 << 13)
-#define GBL_SMI_EN	(1 << 0)
 
 #define TCO_RLD(p)	(TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
 #define TCOv1_TMR(p)	(TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
@@ -357,12 +355,8 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
 
 	tmrval = seconds_to_ticks(p, t);
 
-	/*
-	 * If TCO SMIs are off, the timer counts down twice before rebooting.
-	 * Otherwise, the BIOS generally reboots when the SMI triggers.
-	 */
-	if (p->smi_res &&
-	    (inl(SMI_EN(p)) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
+	/* For TCO v1 the timer counts down twice before rebooting */
+	if (p->iTCO_version == 1)
 		tmrval /= 2;
 
 	/* from the specs: */
@@ -527,7 +521,7 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
 		 * Disables TCO logic generating an SMI#
 		 */
 		val32 = inl(SMI_EN(p));
-		val32 &= ~TCO_EN;	/* Turn off SMI clearing watchdog */
+		val32 &= 0xffffdfff;	/* Turn off SMI clearing watchdog */
 		outl(val32, SMI_EN(p));
 	}