watchdog: intel_oc_wdt: Do not try to write into const memory

The code tries to update the intel_oc_wdt_info data structure if the
watchdog is locked. That data structure is marked as const and can not
be written into. Copy it into struct intel_oc_wdt and modify it there
to fix the problem.

Reported-by: Petar Kulić <[e-mail]>
Cc: Diogo Ivo <[e-mail]>
Fixes: 535d1784d8a9 ("watchdog: Add driver for Intel OC WDT")
Signed-off-by: Guenter Roeck <[e-mail]>
Reviewed-by: Diogo Ivo <[e-mail]>
Tested-by: Diogo Ivo <[e-mail]>
Link: https://lore.kernel.org/linux-watchdog/[e-mail]/T/#t
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/intel_oc_wdt.c

···
 struct intel_oc_wdt {
 	struct watchdog_device wdd;
 	struct resource *ctrl_res;
+	struct watchdog_info info;
 	bool locked;
 };
 
···
 
 static int intel_oc_wdt_setup(struct intel_oc_wdt *oc_wdt)
 {
-	struct watchdog_info *info;
 	unsigned long val;
 
 	val = inl(INTEL_OC_WDT_CTRL_REG(oc_wdt));
···
 		set_bit(WDOG_HW_RUNNING, &oc_wdt->wdd.status);
 
 		if (oc_wdt->locked) {
-			info = (struct watchdog_info *)&intel_oc_wdt_info;
 			/*
 			 * Set nowayout unconditionally as we cannot stop
 			 * the watchdog.
···
 			 * and inform the core we can't change it.
 			 */
 			oc_wdt->wdd.timeout = (val & INTEL_OC_WDT_TOV) + 1;
-			info->options &= ~WDIOF_SETTIMEOUT;
+			oc_wdt->info.options &= ~WDIOF_SETTIMEOUT;
 
 			dev_info(oc_wdt->wdd.parent,
 				 "Register access locked, heartbeat fixed at: %u s\n",
···
 	wdd->min_timeout = INTEL_OC_WDT_MIN_TOV;
 	wdd->max_timeout = INTEL_OC_WDT_MAX_TOV;
 	wdd->timeout = INTEL_OC_WDT_DEF_TOV;
-	wdd->info = &intel_oc_wdt_info;
+	oc_wdt->info = intel_oc_wdt_info;
+	wdd->info = &oc_wdt->info;
 	wdd->ops = &intel_oc_wdt_ops;
 	wdd->parent = dev;