[PATCH 01/42] hw/watchdog/wdt_imx2: Fix handling of write-once WCR bits

[Bernhard Beschow]

Guests such as u-boot may experience inadvertant reboots when configuring
the WCR register. Apparently there is a typo in the WCR locked bits
handling: The locked values for s->wcr must come from itself rather than
from s->wicr. While at it remove the redundant locked attributes for the
bits which stick to one once written with one.

Note that removing the locked attributes required a migration break. Defer
that to a subsequent patch to help backporting.

Fixes: daca13d495a1 ("hw/watchdog: Implement full i.MX watchdog
support")
cc: qemu-stable
Signed-off-by: Bernhard Beschow <shen...@gmail.com>
---
 hw/watchdog/wdt_imx2.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/hw/watchdog/wdt_imx2.c b/hw/watchdog/wdt_imx2.c
index c83d4107c1..aaf4695db2 100644
--- a/hw/watchdog/wdt_imx2.c
+++ b/hw/watchdog/wdt_imx2.c
@@ -59,9 +59,8 @@ static void imx2_wdt_reset(DeviceState *dev)
 
     s->wicr_locked = false;
     s->wcr_locked = false;
-    s->wcr_wde_locked = false;
 
-    s->wcr = IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS;
+    s->wcr = IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS | (s->wcr & IMX2_WDT_WCR_WDT);
     s->wsr = 0;
     s->wrsr &= ~(IMX2_WDT_WRSR_TOUT | IMX2_WDT_WRSR_SFTW);
     s->wicr = IMX2_WDT_WICR_WICT_DEF;
@@ -156,23 +155,11 @@ static void imx2_wdt_write(void *opaque, hwaddr addr,
     case IMX2_WDT_WCR:
         if (s->wcr_locked) {
             value &= ~IMX2_WDT_WCR_LOCK_MASK;
-            value |= (s->wicr & IMX2_WDT_WCR_LOCK_MASK);
+            value |= (s->wcr & IMX2_WDT_WCR_LOCK_MASK);
         }
         s->wcr_locked = true;
-        if (s->wcr_wde_locked) {
-            value &= ~IMX2_WDT_WCR_WDE;
-            value |= (s->wicr & ~IMX2_WDT_WCR_WDE);
-        } else if (value & IMX2_WDT_WCR_WDE) {
-            s->wcr_wde_locked = true;
-        }
-        if (s->wcr_wdt_locked) {
-            value &= ~IMX2_WDT_WCR_WDT;
-            value |= (s->wicr & ~IMX2_WDT_WCR_WDT);
-        } else if (value & IMX2_WDT_WCR_WDT) {
-            s->wcr_wdt_locked = true;
-        }
 
-        s->wcr = value;
+        s->wcr = value | (s->wcr & (IMX2_WDT_WCR_WDT | IMX2_WDT_WCR_WDE));
         if (!(value & IMX2_WDT_WCR_SRS)) {
             s->wrsr = IMX2_WDT_WRSR_SFTW;
         }
-- 
2.55.0