watchdog: bcm2835_wdt: set WDOG_HW_RUNNING bit when appropriate

A bootloader may start the watchdog device before handing control to
the kernel - in that case, we should tell the kernel about it so the
watchdog framework can keep it alive until userspace opens
/dev/watchdog0.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
index 4dddd8298a22..c32c45bd8b09 100644
--- a/drivers/watchdog/bcm2835_wdt.c
+++ b/drivers/watchdog/bcm2835_wdt.c
@@ -55,6 +55,15 @@ struct bcm2835_wdt {
 static unsigned int heartbeat;
 static bool nowayout = WATCHDOG_NOWAYOUT;
 
+static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
+{
+        uint32_t cur;
+
+        cur = readl(wdt->base + PM_RSTC);
+
+        return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
+}
+
 static int bcm2835_wdt_start(struct watchdog_device *wdog)
 {
         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
@@ -181,6 +190,17 @@ static int bcm2835_wdt_probe(struct platform_device *pdev)
         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
         bcm2835_wdt_wdd.parent = &pdev->dev;
+        if (bcm2835_wdt_is_running(wdt)) {
+                /*
+                 * The currently active timeout value (set by the
+                 * bootloader) may be different from the module
+                 * heartbeat parameter or the value in device
+                 * tree. But we just need to set WDOG_HW_RUNNING,
+                 * because then the framework will "immediately" ping
+                 * the device, updating the timeout.
+                 */
+                set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
+        }
         err = watchdog_register_device(&bcm2835_wdt_wdd);
         if (err) {
                 dev_err(dev, "Failed to register watchdog device");