watchdog: sama5d4: fix WDDIS handling

[karo-tx-linux.git] / drivers / watchdog / sama5d4_wdt.c

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index f709962018ac260107dd2c419c1fbcdfafd4599b..5cee20caca78c8dcd9e44710eabeb932891947da 100644 (file)
--- 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;
 }