On 12/12/2016 01:48 AM, Rasmus Villemoes wrote:
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@xxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
drivers/watchdog/bcm2835_wdt.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
index 4dddd82..c32c45b 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");
--
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