Triggering the watchdog faster than T_WDMIN=256ms leads to resets of the
da9063 chip. The datasheet says that the watchdog must only be triggered
in the timeframe T_WDMIN to T_WDMAX. The T_WDMAX is configured in the
driver.
This problem was already mentioned in the patch:
http://comments.gmane.org/gmane.linux.watchdog/1708
You also could say that this behavior is a feature. When the userspace
goes wild, triggering the watchdog to fast, the system is reseted. But
there is currently no information in the watchdog ABI to report a
minimum wait time between two watchdog heartbeats.
The code is taken from the watchdog driver da9062_wdt.c.
Signed-off-by: Stefan Christ <s.christ@xxxxxxxxx>
---
drivers/watchdog/da9063_wdt.c | 45 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 41 insertions(+), 4 deletions(-)
diff --git a/drivers/watchdog/da9063_wdt.c b/drivers/watchdog/da9063_wdt.c
index e2fe2eb..f7bdfb1 100644
--- a/drivers/watchdog/da9063_wdt.c
+++ b/drivers/watchdog/da9063_wdt.c
@@ -35,13 +35,36 @@ static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
#define DA9063_WDT_MIN_TIMEOUT wdt_timeout[DA9063_TWDSCALE_MIN]
#define DA9063_WDT_MAX_TIMEOUT wdt_timeout[DA9063_TWDSCALE_MAX]
#define DA9063_WDG_TIMEOUT wdt_timeout[3]
+#define DA9063_RESET_PROTECTION_MS 256
struct da9063_watchdog {
struct da9063 *da9063;
struct watchdog_device wdtdev;
struct notifier_block restart_handler;
+ unsigned long j_time_stamp;
};
+static void da9063_set_window_start(struct da9063_watchdog *wdt)
+{
+ wdt->j_time_stamp = jiffies;
+}
+
+static void da9063_apply_window_protection(struct da9063_watchdog *wdt)
+{
+ unsigned long delay = msecs_to_jiffies(DA9063_RESET_PROTECTION_MS);
+ unsigned long timeout = wdt->j_time_stamp + delay;
+ unsigned long now = jiffies;
+ unsigned int diff_ms;
+
+ /* if time-limit has not elapsed then wait for remainder */
+ if (time_before(now, timeout)) {
+ diff_ms = jiffies_to_msecs(timeout-now);
+ dev_dbg(wdt->da9063->dev,
+ "Kicked too quickly. Delaying %u msecs\n", diff_ms);
+ msleep(diff_ms);
+ }
+}
+
static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
{
unsigned int i;
@@ -54,10 +77,18 @@ static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
return DA9063_TWDSCALE_MAX;
}
-static int _da9063_wdt_set_timeout(struct da9063 *da9063, unsigned int regval)
+static int _da9063_wdt_set_timeout(struct da9063_watchdog *wdt, unsigned int regval)
{
- return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
+ int ret;
+
+ da9063_apply_window_protection(wdt);
+
+ ret = regmap_update_bits(wdt->da9063->regmap, DA9063_REG_CONTROL_D,
DA9063_TWDSCALE_MASK, regval);
+
+ da9063_set_window_start(wdt);
+
+ return ret;
}
static int da9063_wdt_start(struct watchdog_device *wdd)
@@ -67,7 +98,7 @@ static int da9063_wdt_start(struct watchdog_device *wdd)
int ret;
selector = da9063_wdt_timeout_to_sel(wdt->wdtdev.timeout);
- ret = _da9063_wdt_set_timeout(wdt->da9063, selector);
+ ret = _da9063_wdt_set_timeout(wdt, selector);
if (ret)
dev_err(wdt->da9063->dev, "Watchdog failed to start (err = %d)\n",
ret);
@@ -94,12 +125,16 @@ static int da9063_wdt_ping(struct watchdog_device *wdd)
struct da9063_watchdog *wdt = watchdog_get_drvdata(wdd);
int ret;
+ da9063_apply_window_protection(wdt);
+
ret = regmap_write(wdt->da9063->regmap, DA9063_REG_CONTROL_F,
DA9063_WATCHDOG);
if (ret)
dev_alert(wdt->da9063->dev, "Failed to ping the watchdog (err = %d)\n",
ret);
+ da9063_set_window_start(wdt);
+
return ret;
}
@@ -111,7 +146,7 @@ static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
int ret;
selector = da9063_wdt_timeout_to_sel(timeout);
- ret = _da9063_wdt_set_timeout(wdt->da9063, selector);
+ ret = _da9063_wdt_set_timeout(wdt, selector);
if (ret)
dev_err(wdt->da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
ret);
@@ -192,6 +227,8 @@ static int da9063_wdt_probe(struct platform_device *pdev)
dev_err(wdt->da9063->dev,
"Failed to register restart handler (err = %d)\n", ret);
+ da9063_set_window_start(wdt);
+
return 0;
}
--
1.9.1
--
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