SAMA5 WDT: Miss watchdog fixes

arch/arm/src/sama5/sam_boot.c

@@ -494,14 +494,29 @@ static void sam_copyvectorblock(void)
  * Name: sam_wdtdisable
  *
  * Description:
- *   Disable the watchdog timer
+ *   Disable the watchdog timer.  The SAMA5 always boots with the watchdog
+ *   timer enabled at its maximum timeout (16 seconds).  The watchdog timer
+ *   can disabled by writing to the Watchdog Mode Register (WDT_MR).  The
+ *   WDT_MR, however, can be written only one time after the CPU has been
+ *   reset.
+ *
+ *   So if no watchdog timer driver has been configured, the watchdog timer
+ *   must be disabled as part of the start up logic.  But, on the other
+ *   hand, we must not write to the WDT_MR register if the watchdog timer
+ *   driver is configured.  In that case, some later application will
+ *   configure the WDT and begin periodic pinging (within 16 seconds,
+ *   hopefully).
  *
  ****************************************************************************/
 
+#ifndef CONFIG_SAMA5_WDT
 static inline void sam_wdtdisable(void)
 {
   putreg32(WDT_MR_WDDIS, SAM_WDT_MR);
 }
+#else
+#  define sam_wdtdisable()
+#endif
 
 /****************************************************************************
  * Public Functions

arch/arm/src/sama5/sam_wdt.c

@@ -118,11 +118,11 @@ struct sam_lowerhalf_s
 /* Register operations ******************************************************/
 
 #if defined(CONFIG_SAMA5_WDT_REGDEBUG) && defined(CONFIG_DEBUG)
-static uint16_t sam_getreg(uint32_t addr);
+static uint32_t sam_getreg(uintptr_t regaddr);
-static void     sam_putreg(uint16_t val, uint32_t addr);
+static void     sam_putreg(uint32_t regval, uintptr_t regaddr);
 #else
-# define        sam_getreg(addr)     getreg32(addr)
+# define        sam_getreg(regaddr)        getreg32(regaddr)
-# define        sam_putreg(val,addr) putreg32(val,addr)
+# define        sam_putreg(regval,regaddr) putreg32(regval,regaddr)
 #endif
 
 /* Interrupt hanlding *******************************************************/
@@ -178,21 +178,21 @@ static struct sam_lowerhalf_s g_wdtdev;
  ****************************************************************************/
 
 #if defined(CONFIG_SAMA5_WDT_REGDEBUG) && defined(CONFIG_DEBUG)
-static uint16_t sam_getreg(uint32_t addr)
+static uint32_t sam_getreg(uintptr_t regaddr)
 {
   static uint32_t prevaddr = 0;
-  static uint32_t count = 0;
+  static uint32_t count    = 0;
-  static uint16_t preval = 0;
+  static uint32_t preval   = 0;
 
   /* Read the value from the register */
 
-  uint16_t val = getreg16(addr);
+  uint32_t regval = getreg32(regaddr);
 
   /* Is this the same value that we read from the same registe last time?  Are
    * we polling the register?  If so, suppress some of the output.
    */
 
-  if (addr == prevaddr && val == preval)
+  if (regaddr == prevaddr && regval == preval)
     {
       if (count == 0xffffffff || ++count > 3)
         {
@@ -200,7 +200,7 @@ static uint16_t sam_getreg(uint32_t addr)
              {
                lldbg("...\n");
              }
-          return val;
+          return regval;
         }
     }
 
@@ -219,15 +219,15 @@ static uint16_t sam_getreg(uint32_t addr)
 
        /* Save the new address, value, and count */
 
-       prevaddr = addr;
+       prevaddr = regaddr;
-       preval   = val;
+       preval   = regval;
        count    = 1;
     }
 
   /* Show the register value read */
 
-  lldbg("%08x->%04x\n", addr, val);
+  lldbg("%08x->%048\n", regaddr, regval);
-  return val;
+  return regval;
 }
 #endif
 
@@ -240,15 +240,15 @@ static uint16_t sam_getreg(uint32_t addr)
  ****************************************************************************/
 
 #if defined(CONFIG_SAMA5_WDT_REGDEBUG) && defined(CONFIG_DEBUG)
-static void sam_putreg(uint16_t val, uint32_t addr)
+static void sam_putreg(uint32_t regval, uintptr_t regaddr)
 {
   /* Show the register value being written */
 
-  lldbg("%08x<-%04x\n", addr, val);
+  lldbg("%08x<-%08x\n", regaddr, regval);
 
   /* Write the value */
 
-  putreg16(val, addr);
+  putreg32(regval, regaddr);
 }
 #endif
 
@@ -304,6 +304,8 @@ static int sam_interrupt(int irq, FAR void *context)
 
 static int sam_start(FAR struct watchdog_lowerhalf_s *lower)
 {
+  FAR struct sam_lowerhalf_s *priv = (FAR struct sam_lowerhalf_s *)lower;
+
   /* The watchdog timer is enabled or disabled by writing to the MR register.
    *
    * NOTE: The Watchdog Mode Register (WDT_MR) can be written only once.  Only
@@ -312,7 +314,7 @@ static int sam_start(FAR struct watchdog_lowerhalf_s *lower)
    */
 
   wdvdbg("Entry\n");
-  return -ENOSYS;
+  return priv->started ? OK : -ENOSYS;
 }
 
 /****************************************************************************
@@ -389,7 +391,7 @@ static int sam_keepalive(FAR struct watchdog_lowerhalf_s *lower)
  ****************************************************************************/
 
 static int sam_getstatus(FAR struct watchdog_lowerhalf_s *lower,
-                           FAR struct watchdog_status_s *status)
+                         FAR struct watchdog_status_s *status)
 {
   FAR struct sam_lowerhalf_s *priv = (FAR struct sam_lowerhalf_s *)lower;
 
@@ -403,7 +405,7 @@ static int sam_getstatus(FAR struct watchdog_lowerhalf_s *lower,
     {
       status->flags |= WDFLAGS_ACTIVE;
     }
- 
+
 #ifdef CONFIG_SAMA5_WDT_INTERRUPT
   if (priv->handler)
     {
@@ -494,7 +496,7 @@ static int sam_settimeout(FAR struct watchdog_lowerhalf_s *lower,
 
   wdvdbg("reload=%d timout: %d->%d\n",
          reload, timeout, priv->timeout);
-  
+
   /* Set the WDT_MR according to calculated value
    *
    * NOTE: The Watchdog Mode Register (WDT_MR) can be written only once.  Only
@@ -624,7 +626,7 @@ static xcpt_t sam_capture(FAR struct watchdog_lowerhalf_s *lower,
 static int sam_ioctl(FAR struct watchdog_lowerhalf_s *lower, int cmd,
                     unsigned long arg)
 {
-  wdvdbg("Entry: cmd=%d arg=%ld\n", cmd, arg);
+  wdvdbg("cmd=%d arg=%ld\n", cmd, arg);
 
   /* No ioctls are supported */
 
@@ -636,7 +638,7 @@ static int sam_ioctl(FAR struct watchdog_lowerhalf_s *lower, int cmd,
  ****************************************************************************/
 
 /****************************************************************************
- * Name: sam_wdtinitialize
+ * Name: up_wdginitialize
  *
  * Description:
  *   Initialize the WDT watchdog time.  The watchdog timer is intialized and
@@ -644,21 +646,29 @@ static int sam_ioctl(FAR struct watchdog_lowerhalf_s *lower, int cmd,
  *   disabled.
  *
  * Input Parameters:
- *   devpath - The full path to the watchdog.  This should be of the form
+ *   None
- *     /dev/watchdog0
  *
  * Returned Values:
  *   None
  *
  ****************************************************************************/
 
-void sam_wdtinitialize(FAR const char *devpath)
+int up_wdginitialize(void)
 {
   FAR struct sam_lowerhalf_s *priv = &g_wdtdev;
 
-  wdvdbg("Entry: devpath=%s\n", devpath);
+  wdvdbg("Entry: CR: %08x MR: %08x SR: %08x\n",
+         sam_getreg(SAM_WDT_CR), sam_getreg(SAM_WDT_MR),
+         sam_getreg(SAM_WDT_SR));
 
-  /* No clocking setup is required.  The Watchdog Timer uses the Slow Clock
+  /* Check if some previous logic was disabled the watchdog timer.  Since the
+   * MR can be written only one time, we are out of business if that is the
+   * case.
+   */
+
+  DEBUGASSERT((sam_getreg(SAM_WDT_MR) & WDT_MR_WDDIS) != 0);
+
+  /* No clock setup is required.  The Watchdog Timer uses the Slow Clock
    * divided by 128 to establish the maximum Watchdog period to be 16 seconds
    * (with a typical Slow Clock of 32768 kHz).
    */
@@ -678,7 +688,9 @@ void sam_wdtinitialize(FAR const char *devpath)
 
   /* Register the watchdog driver as /dev/watchdog0 */
 
-  (void)watchdog_register(devpath, (FAR struct watchdog_lowerhalf_s *)priv);
+  (void)watchdog_register("/dev/watchdog0",
+                         (FAR struct watchdog_lowerhalf_s *)priv);
+  return OK;
 }
 
 #endif /* CONFIG_WATCHDOG && CONFIG_SAMA5_WDT */

arch/arm/src/sama5/sam_wdt.h

@@ -65,27 +65,6 @@ extern "C" {
  * Public Functions
  ****************************************************************************/
 
-/****************************************************************************
- * Name: sam_wdtinitialize
- *
- * Description:
- *   Initialize the WDT watchdog timer.  The watchdog timer is intialized and
- *   registered as 'devpath.  The initial state of the watchdog time is
- *   disabled.
- *
- * Input Parameters:
- *   devpath - The full path to the watchdog.  This should be of the form
- *     /dev/watchdog0
- *
- * Returned Values:
- *   None
- *
- ****************************************************************************/
-
-#ifdef CONFIG_SAMA5_WDT
-void sam_wdtinitialize(FAR const char *devpath);
-#endif
-
 #undef EXTERN
 #if defined(__cplusplus)
 }

configs/sama5d3x-ek/README.txt

@@ -1006,7 +1006,7 @@ Configurations
 
     5. The Real Time Clock/Calendar RTC) is enabled.  These are the relevant
        settings:
-    
+
         System Type:
           CONFIG_SAMA5_RTC=y                   : Enable the RTC driver
 
@@ -2152,7 +2152,7 @@ Configurations
         Defaults should be okay for all related settings.
 
     17. The Real Time Clock/Calendar RTC) may be enabled with these settings:
-    
+
         System Type:
           CONFIG_SAMA5_RTC=y                   : Enable the RTC driver
 
@@ -2182,13 +2182,24 @@ Configurations
           CONFIG_WATCHDOG=y                   : Enables watchdog timer driver support
 
         Application Configuration -> Eamples
-          CONFIG_EXAMPLES_WATCHDOG=y          : Enable the apps/examples/watchdog
+          CONFIG_EXAMPLES_WATCHDOG=y          : Enable apps/examples/watchdog
 
         The WDT timer is driven off the slow, 32768Hz clock divided by 128.
         As a result, the watchdog a maximum timeout value of 16 seconds.  The
         SAMA5 WDT may also only be programmed one time; the processor must be
         reset before the WDT can be reprogrammed.
 
+        The SAMA5 always boots with the watchdog timer enabled at its maximum
+        timeout (16 seconds).  In the normal case where no watchdog timer driver
+        has been configured, the watchdog timer is disabled as part of the start
+        up logic.  But, since we are permitted only one opportunity to program
+        the WDT, we cannot disable the watchdog time if CONFIG_SAMA5_WDT=y.  So,
+        be forewarned:  You have only 16 seconds to run your watchdog timer test!
+
+        NOTE:  If you are using the norboot program to run from FLASH as I did,
+        beware that the default version also disables the watchdog.  You will
+        need a special version of norboot with CONFIG_SAMA5_WDT=y.
+
     STATUS:
 
       PCK FREQUENCY