[PATCH 1/1] mx7ulp: Update wdog disable sequence

[Oleksandr Suvorov]

From: Ye Li <ye.li at nxp.com>

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 <ye.li at nxp.com>
Co-developed-by: Jorge Ramirez-Ortiz <jorge at foundries.io>
Signed-off-by: Jorge Ramirez-Ortiz <jorge at foundries.io>
Co-developed-by: Ricardo Salveti <ricardo at foundries.io>
Signed-off-by: Ricardo Salveti <ricardo at foundries.io>
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov at foundries.io>
---

 arch/arm/mach-imx/mx7ulp/soc.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mach-imx/mx7ulp/soc.c b/arch/arm/mach-imx/mx7ulp/soc.c
index 320f24dd29..7f097d6850 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 */
+	u32 val_cs = readl(wdog_base + 0x00);
 
-	writel(REFRESH_WORD0, (wdog_base + 0x04)); /* Refresh the CNT */
-	writel(REFRESH_WORD1, (wdog_base + 0x04));
+	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)
-- 
2.31.1