[PATCH v2 6/9] watchdog: msc313e: Fix undefined behavior

[Tzung-Bi Shih]

readw() returns a u16.  Left shifting a u16 by 16 bits yields undefined
behavior.

Cast to u32 explicitly before the shift.

Fixes: ffd264bd152c ("watchdog: msc313e: Check if the WDT was running at boot")
Signed-off-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
---
v2:
- New to the series.
---
 drivers/watchdog/msc313e_wdt.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/msc313e_wdt.c b/drivers/watchdog/msc313e_wdt.c
index c7d558fefc86..e28261c7a8d4 100644
--- a/drivers/watchdog/msc313e_wdt.c
+++ b/drivers/watchdog/msc313e_wdt.c
@@ -31,6 +31,16 @@ struct msc313e_wdt_priv {
 	struct clk *clk;
 };
 
+static u32 msc313e_wdt_get_hw_timeout(struct msc313e_wdt_priv *priv)
+{
+	u16 low, high;
+
+	low = readw(priv->base + REG_WDT_MAX_PRD_L);
+	high = readw(priv->base + REG_WDT_MAX_PRD_H);
+
+	return ((u32)high << 16) | low;
+}
+
 static void msc313e_wdt_set_hw_timeout(struct msc313e_wdt_priv *priv,
 				       unsigned int timeout)
 {
@@ -139,7 +149,7 @@ static int msc313e_wdt_probe(struct platform_device *pdev)
 		return ret;
 
 	/* If the period is non-zero the WDT is running */
-	if (readw(priv->base + REG_WDT_MAX_PRD_L) | (readw(priv->base + REG_WDT_MAX_PRD_H) << 16)) {
+	if (msc313e_wdt_get_hw_timeout(priv)) {
 		set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
 		/*
 		 * Keep the clock enabled. The watchdog core will skip the next
-- 
2.53.0