1 files changed, 30 insertions, 18 deletions

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index f709962..5cee20c 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -44,6 +44,8 @@ MODULE_PARM_DESC(nowayout,
 	"Watchdog cannot be stopped once started (default="
 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
+
 #define wdt_read(wdt, field) \
 	readl_relaxed((wdt)->reg_base + (field))
 
@@ -89,7 +91,16 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
 	wdt->mr &= ~AT91_WDT_WDD;
 	wdt->mr |= AT91_WDT_SET_WDV(value);
 	wdt->mr |= AT91_WDT_SET_WDD(value);
-	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+
+	/*
+	 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
+	 * setting the WDDIS bit, and while it is set, the fields WDV and WDD
+	 * must not be modified.
+	 * If the watchdog is enabled, then the timeout can be updated. Else,
+	 * wait that the user enables it.
+	 */
+	if (wdt_enabled)
+		wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
 
 	wdd->timeout = timeout;
 
@@ -145,23 +156,20 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 
 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 {
-	struct watchdog_device *wdd = &wdt->wdd;
-	u32 value = WDT_SEC2TICKS(wdd->timeout);
 	u32 reg;
-
 	/*
-	 * Because the fields WDV and WDD must not be modified when the WDDIS
-	 * bit is set, so clear the WDDIS bit before writing the WDT_MR.
+	 * When booting and resuming, the bootloader may have changed the
+	 * watchdog configuration.
+	 * If the watchdog is already running, we can safely update it.
+	 * Else, we have to disable it properly.
 	 */
-	reg = wdt_read(wdt, AT91_WDT_MR);
-	reg &= ~AT91_WDT_WDDIS;
-	wdt_write(wdt, AT91_WDT_MR, reg);
-
-	wdt->mr |= AT91_WDT_SET_WDD(value);
-	wdt->mr |= AT91_WDT_SET_WDV(value);
-
-	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
-
+	if (wdt_enabled) {
+		wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+	} else {
+		reg = wdt_read(wdt, AT91_WDT_MR);
+		if (!(reg & AT91_WDT_WDDIS))
+			wdt_write(wdt, AT91_WDT_MR, reg | AT91_WDT_WDDIS);
+	}
 	return 0;
 }
 
@@ -172,6 +180,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	struct resource *res;
 	void __iomem *regs;
 	u32 irq = 0;
+	u32 timeout;
 	int ret;
 
 	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
@@ -221,6 +230,11 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	timeout = WDT_SEC2TICKS(wdd->timeout);
+
+	wdt->mr |= AT91_WDT_SET_WDD(timeout);
+	wdt->mr |= AT91_WDT_SET_WDV(timeout);
+
 	ret = sama5d4_wdt_init(wdt);
 	if (ret)
 		return ret;
@@ -263,9 +277,7 @@ static int sama5d4_wdt_resume(struct device *dev)
 {
 	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 
-	wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
-	if (wdt->mr & AT91_WDT_WDDIS)
-		wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+	sama5d4_wdt_init(wdt);
 
 	return 0;
 }