[PATCH V2 41/46] mx7ulp: wdog: Wait for WDOG unlock and reconfiguration to complete

[Peng Fan (OSS)]

From: Breno Lima <breno.lima at nxp.com>

According to i.MX7ULP Reference Manual we should wait for WDOG unlock
and reconfiguration to complete.

Section "59.5.3 Configure Watchdog" provides the following example:

DisableInterrupts; //disable global interrupt
WDOG_CNT = 0xD928C520; //unlock watchdog
while(WDOG_CS[ULK]==0); //wait until registers are unlocked
WDOG_TOVAL = 256; //set timeout value
WDOG_CS = WDOG_CS_EN(1) | WDOG_CS_CLK(1) | WDOG_CS_INT(1) |
	  WDOG_CS_WIN(0) | WDOG_CS_UPDATE(1);
while(WDOG_CS[RCS]==0); //wait until new configuration takes effect
EnableInterrupts; //enable global interrupt

Update U-Boot WDOG driver to align with i.MX7ULP reference manual.

Use 32 bits accessing to CS register. According to RM, the bits in
this register only can write once after unlock. So using 8 bits access
will cause problem.

Reviewed-by: Ye Li <ye.li at nxp.com>
Signed-off-by: Breno Lima <breno.lima at nxp.com>
Signed-off-by: Peng Fan <peng.fan at nxp.com>
---
 drivers/watchdog/ulp_wdog.c | 39 ++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/drivers/watchdog/ulp_wdog.c b/drivers/watchdog/ulp_wdog.c
index 490a2c94ec..ecd35ef22a 100644
--- a/drivers/watchdog/ulp_wdog.c
+++ b/drivers/watchdog/ulp_wdog.c
@@ -12,9 +12,7 @@
  * MX7ULP WDOG Register Map
  */
 struct wdog_regs {
-	u8 cs1;
-	u8 cs2;
-	u16 reserve0;
+	u32 cs;
 	u32 cnt;
 	u32 toval;
 	u32 win;
@@ -30,10 +28,12 @@ struct wdog_regs {
 #define UNLOCK_WORD0 0xC520 /* 1st unlock word */
 #define UNLOCK_WORD1 0xD928 /* 2nd unlock word */
 
-#define WDGCS1_WDGE                      (1<<7)
-#define WDGCS1_WDGUPDATE                 (1<<5)
+#define WDGCS_WDGE                      BIT(7)
+#define WDGCS_WDGUPDATE                 BIT(5)
 
-#define WDGCS2_FLG                       (1<<6)
+#define WDGCS_RCS                       BIT(10)
+#define WDGCS_ULK                       BIT(11)
+#define WDGCS_FLG                       BIT(14)
 
 #define WDG_BUS_CLK                      (0x0)
 #define WDG_LPO_CLK                      (0x1)
@@ -60,7 +60,6 @@ void hw_watchdog_reset(void)
 
 void hw_watchdog_init(void)
 {
-	u8 val;
 	struct wdog_regs *wdog = (struct wdog_regs *)WDOG_BASE_ADDR;
 
 	dmb();
@@ -68,15 +67,19 @@ void hw_watchdog_init(void)
 	__raw_writel(UNLOCK_WORD1, &wdog->cnt);
 	dmb();
 
-	val = readb(&wdog->cs2);
-	val |= WDGCS2_FLG;
-	writeb(val, &wdog->cs2);
+	/* Wait WDOG Unlock */
+	while (!(readl(&wdog->cs) & WDGCS_ULK))
+		;
 
 	hw_watchdog_set_timeout(CONFIG_WATCHDOG_TIMEOUT_MSECS);
 	writel(0, &wdog->win);
 
-	writeb(WDG_LPO_CLK, &wdog->cs2);/* setting 1-kHz clock source */
-	writeb((WDGCS1_WDGE | WDGCS1_WDGUPDATE), &wdog->cs1);/* enable counter running */
+	/* setting 1-kHz clock source, enable counter running, and clear interrupt */
+	writel((WDGCS_WDGE | WDGCS_WDGUPDATE |(WDG_LPO_CLK << 8) | WDGCS_FLG), &wdog->cs);
+
+	/* Wait WDOG reconfiguration */
+	while (!(readl(&wdog->cs) & WDGCS_RCS))
+		;
 
 	hw_watchdog_reset();
 }
@@ -90,11 +93,19 @@ void reset_cpu(void)
 	__raw_writel(UNLOCK_WORD1, &wdog->cnt);
 	dmb();
 
+	/* Wait WDOG Unlock */
+	while (!(readl(&wdog->cs) & WDGCS_ULK))
+		;
+
 	hw_watchdog_set_timeout(5); /* 5ms timeout */
 	writel(0, &wdog->win);
 
-	writeb(WDG_LPO_CLK, &wdog->cs2);/* setting 1-kHz clock source */
-	writeb(WDGCS1_WDGE, &wdog->cs1);/* enable counter running */
+	/* enable counter running */
+	writel((WDGCS_WDGE | (WDG_LPO_CLK << 8)), &wdog->cs);
+
+	/* Wait WDOG reconfiguration */
+	while (!(readl(&wdog->cs) & WDGCS_RCS))
+		;
 
 	hw_watchdog_reset();
 
-- 
2.30.0