watchdog: it8712f_wdt: Add module parameter for alternative reset sources

On iEi PCISA-9652-R10 (BIOS version 1.5) single board computer reads
from the game port do not seem to reset the watchdog timer. This patch
adds a module parameter wdt_config_reg to specify alternative reset
sources. At least WDT_RESET_KBD has been tested, even just running

while true; do
    setleds -L +scroll
    sleep 1
    setleds -L -scroll
    sleep 1
done

is enough to keep the watchdog happy.
Signed-off-by: Timo Juhani Lindfors <timo.lindfors@iki.fi>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/it8712f_wdt.c

@@ -85,6 +85,14 @@ static unsigned short address;
 #define WDT_OUT_PWROK	0x10	/* Pulse PWROK on timeout */
 #define WDT_OUT_KRST	0x40	/* Pulse reset on timeout */
 
+static int wdt_control_reg = WDT_RESET_GAME;
+module_param(wdt_control_reg, int, 0);
+MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
+		"register. The default WDT_RESET_GAME resets the timer on "
+		"game port reads that this driver generates. You can also "
+		"use KBD, MOUSE or CIR if you have some external way to "
+		"generate those interrupts.");
+
 static int superio_inb(int reg)
 {
 	outb(reg, REG);
@@ -131,7 +139,8 @@ static inline void superio_exit(void)
 
 static inline void it8712f_wdt_ping(void)
 {
-	inb(address);
+	if (wdt_control_reg & WDT_RESET_GAME)
+		inb(address);
 }
 
 static void it8712f_wdt_update_margin(void)
@@ -170,7 +179,7 @@ static void it8712f_wdt_enable(void)
 	superio_enter();
 	superio_select(LDN_GPIO);
 
-	superio_outb(WDT_RESET_GAME, WDT_CONTROL);
+	superio_outb(wdt_control_reg, WDT_CONTROL);
 
 	it8712f_wdt_update_margin();