Hi, On 10/23/14 13:40, Timo Kokkonen wrote:
By default the driver will start a kernel timer which keeps on kicking the watchdog HW until user space has opened the watchdog device. Usually this is desirable as the watchdog HW is running by default and the user space may not have any watchdog daemon running at all. However, on production systems it may be mandatory that also early crashes and lockups will lead to a watchdog reset, even if they happen before the user space has opened the watchdog device. To resolve the issue, add a new device tree property "atmel,no-early-timer" which will prevent the kernel timer from pinging the watchdog HW on behalf of user space. The default is still to use kernel timer, but more strict behavior can be enabled via the device tree property.
Any thoughts on this one? Should I resend this with some more people or lists to get someone to comment or review this patch?
Thanks, -Timo
Signed-off-by: Timo Kokkonen <timo.kokkonen@xxxxxxxxxx> --- Documentation/devicetree/bindings/watchdog/atmel-wdt.txt | 4 ++++ drivers/watchdog/at91sam9_wdt.c | 6 +++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt index f90e294..1b9289e 100644 --- a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt +++ b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt @@ -28,6 +28,10 @@ Optional properties: entering idle state. - atmel,dbg-halt : Should be present if you want to stop the watchdog when entering debug state. +- atmel,no-early-timer : Should be present if you want to let the + watchdog timer to expire even before user space has opened the + device. If not set, a kernel timer will keep on pinging the + watchdog until it is opened. Example: watchdog@fffffd40 { diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c index 489729b..8cac712 100644 --- a/drivers/watchdog/at91sam9_wdt.c +++ b/drivers/watchdog/at91sam9_wdt.c @@ -89,6 +89,7 @@ struct at91wdt { u32 mr_mask; unsigned long heartbeat; /* WDT heartbeat in jiffies */ bool nowayout; + bool no_early_timer; unsigned int irq; }; @@ -122,7 +123,7 @@ static void at91_ping(unsigned long data) { struct at91wdt *wdt = (struct at91wdt *)data; if (time_before(jiffies, wdt->next_heartbeat) || - !watchdog_active(&wdt->wdd)) { + (!watchdog_active(&wdt->wdd) && !wdt->no_early_timer)) { at91_wdt_reset(wdt); mod_timer(&wdt->timer, jiffies + wdt->heartbeat); } else { @@ -316,6 +317,9 @@ static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt) wdt->mr |= max | ((max - min) << 16); + if (of_property_read_bool(np, "atmel,no-early-timer")) + wdt->no_early_timer = 1; + return 0; } #else
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