On 07/15/2016 01:15 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.
Separate note: The maximum timeout for this watchdog is 15 seconds.
Given that, it might be useful to set max_hw_heartbeat_ms instead of
max_timeout. Separate patch, though.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@xxxxxxxxx>
---
drivers/watchdog/bcm2835_wdt.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
index 4dddd82..9a08334 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);
@@ -70,6 +79,7 @@ static int bcm2835_wdt_start(struct watchdog_device *wdog)
PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
spin_unlock_irqrestore(&wdt->lock, flags);
+ set_bit(WDOG_HW_RUNNING, &wdog->status);
You don't need to set this bit here unless the watchdog can not be stopped.
return 0;
}
@@ -79,6 +89,7 @@ static int bcm2835_wdt_stop(struct watchdog_device *wdog)
struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
+ clear_bit(WDOG_HW_RUNNING, &wdog->status);
... and since you clear the bit, it can be stopped. Both setting and resetting the bit
is therefore not necessary.
return 0;
}
@@ -181,6 +192,17 @@ 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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