mx7ulp: Update wdog disable sequence

Update the mx7ulp wdog disable sequence to avoid potential reset
issue in unlock or refresh sequence. Both sequence need two words
write to wdog CNT register in 16 bus clocks window, if miss the
window, the write will cause violation in wdog and reset the chip.

Current u-boot code is using writel() function which has a DMB
barrier to order the memory access. The DMB between two words write
may introduce some delay in certain circumstance, causing the wdog
reset due to 16 bus clock window requirement.

Also, WDOG1 might have been enabled already depending on FUSE hence
we need to be as close as possible to its reconfiguration timing
requirement of 128 bus clock limit.

This patch replaces writel() function by __raw_writel() to avoid such
issue, and improve to check if watchdog is already disabled or
unlocked.

Signed-off-by: Ye Li <[email protected]>
Co-developed-by: Jorge Ramirez-Ortiz <[email protected]>
Signed-off-by: Jorge Ramirez-Ortiz <[email protected]>
Co-developed-by: Ricardo Salveti <[email protected]>
Signed-off-by: Ricardo Salveti <[email protected]>
Signed-off-by: Oleksandr Suvorov <[email protected]>

1 files changed, 25 insertions, 8 deletions

diff --git a/arch/arm/mach-imx/mx7ulp/soc.c b/arch/arm/mach-imx/mx7ulp/soc.c
index 320f24dd296..7f097d68503 100644
--- a/arch/arm/mach-imx/mx7ulp/soc.c
+++ b/arch/arm/mach-imx/mx7ulp/soc.c
@@ -93,14 +93,31 @@ int board_postclk_init(void)
 
 static void disable_wdog(u32 wdog_base)
 {
-	writel(UNLOCK_WORD0, (wdog_base + 0x04));
-	writel(UNLOCK_WORD1, (wdog_base + 0x04));
-	writel(0x0, (wdog_base + 0x0C)); /* Set WIN to 0 */
-	writel(0x400, (wdog_base + 0x08)); /* Set timeout to default 0x400 */
-	writel(0x120, (wdog_base + 0x00)); /* Disable it and set update */
-
-	writel(REFRESH_WORD0, (wdog_base + 0x04)); /* Refresh the CNT */
-	writel(REFRESH_WORD1, (wdog_base + 0x04));
+	u32 val_cs = readl(wdog_base + 0x00);
+
+	if (!(val_cs & 0x80))
+		return;
+
+	dmb();
+	__raw_writel(REFRESH_WORD0, (wdog_base + 0x04)); /* Refresh the CNT */
+	__raw_writel(REFRESH_WORD1, (wdog_base + 0x04));
+	dmb();
+
+	if (!(val_cs & 800)) {
+		dmb();
+		__raw_writel(UNLOCK_WORD0, (wdog_base + 0x04));
+		__raw_writel(UNLOCK_WORD1, (wdog_base + 0x04));
+		dmb();
+
+		while (!(readl(wdog_base + 0x00) & 0x800));
+	}
+	dmb();
+	__raw_writel(0x0, wdog_base + 0x0C); /* Set WIN to 0 */
+	__raw_writel(0x400, wdog_base + 0x08); /* Set timeout to default 0x400 */
+	__raw_writel(0x120, wdog_base + 0x00); /* Disable it and set update */
+	dmb();
+
+	while (!(readl(wdog_base + 0x00) & 0x400));
 }
 
 void init_wdog(void)