[U-Boot] [PATCH 3/7] ti: wdt: omap: Disable watchdog timer before performing initialization

[Lukasz Majewski <lukma@denx.de>]

The OMAP WDT IP block requires to be stopped before any write to its
registers is performed.

This problem has been thoroughly described in Linux kernel:

"watchdog: omap: assert the counter being stopped before reprogramming:
SHA1: 530c11d432727c697629ad5f9d00ee8e2864d453

Signed-off-by: Lukasz Majewski <lukma@denx.de>
---
 drivers/watchdog/omap_wdt.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/drivers/watchdog/omap_wdt.c b/drivers/watchdog/omap_wdt.c
index 7ea4b60..7b1f429 100644
--- a/drivers/watchdog/omap_wdt.c
+++ b/drivers/watchdog/omap_wdt.c
@@ -81,10 +81,32 @@ static int omap_wdt_set_timeout(unsigned int timeout)
 	return 0;
 }
 
+void hw_watchdog_disable(void)
+{
+	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
+
+	/*
+	 * Disable watchdog
+	 */
+	writel(0xAAAA, &wdt->wdtwspr);
+	while (readl(&wdt->wdtwwps) != 0x0)
+		;
+	writel(0x5555, &wdt->wdtwspr);
+	while (readl(&wdt->wdtwwps) != 0x0)
+		;
+}
+
 void hw_watchdog_init(void)
 {
 	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
 
+	/*
+	 * Make sure the watchdog is disabled. This is unfortunately required
+	 * because writing to various registers with the watchdog running has no
+	 * effect.
+	 */
+	hw_watchdog_disable();
+
 	/* initialize prescaler */
 	while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
 		;
@@ -104,18 +126,3 @@ void hw_watchdog_init(void)
 	while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
 		;
 }
-
-void hw_watchdog_disable(void)
-{
-	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
-
-	/*
-	 * Disable watchdog
-	 */
-	writel(0xAAAA, &wdt->wdtwspr);
-	while (readl(&wdt->wdtwwps) != 0x0)
-		;
-	writel(0x5555, &wdt->wdtwspr);
-	while (readl(&wdt->wdtwwps) != 0x0)
-		;
-}
-- 
2.1.4