Simplified CAN state machine.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@7766 35acf78f-673a-0410-8e92-d51de3d6d3f4

os/hal/dox/can.dox

@@ -48,10 +48,9 @@
     stop -> stop [label="\ncanStop()"];
     stop -> ready [label="\ncanStart()\n(fast implementation)"];
     stop -> starting [label="\ncanStart()\n(slow implementation)"];
-    starting -> starting [label="\ncanStart()\n(other thread)"];
     starting -> ready [label="\ninitialization complete\n(all threads)"];
     ready -> stop [label="\ncanStop()"];
-    ready -> ready [label="\ncanStart()\ncanReceive()\ncanTransmit()"];
+    ready -> ready [label="\ncanReceive()\ncanTransmit()"];
     ready -> sleep [label="\ncanSleep()"];
     sleep -> sleep [label="\ncanSleep()"];
     sleep -> ready [label="\ncanWakeup()"];

os/hal/ports/STM32/LLD/can_lld.c

@@ -429,14 +429,11 @@ void can_lld_start(CANDriver *canp) {
   }
 #endif
 
-  /* Entering initialization mode. */
+  /* Configuring CAN. */
-  canp->state = CAN_STARTING;
   canp->can->MCR = CAN_MCR_INRQ;
   while ((canp->can->MSR & CAN_MSR_INAK) == 0)
     osalThreadSleepS(1);
-  /* BTR initialization.*/
   canp->can->BTR = canp->config->btr;
-  /* MCR initialization.*/
   canp->can->MCR = canp->config->mcr;
 
   /* Interrupt sources initialization.*/

os/hal/src/can.c

@@ -85,9 +85,9 @@ void canObjectInit(CANDriver *canp) {
 
 /**
  * @brief   Configures and activates the CAN peripheral.
- * @note    Activating the CAN bus can be a slow operation this this function
+ * @note    Activating the CAN bus can be a slow operation.
- *          is not atomic, it waits internally for the initialization to
+ * @note    Unlike other drivers it is not possible to restart the CAN
- *          complete.
+ *          driver without first stopping it using canStop().
  *
  * @param[in] canp      pointer to the @p CANDriver object
  * @param[in] config    pointer to the @p CANConfig object. Depending on
@@ -100,18 +100,18 @@ void canStart(CANDriver *canp, const CANConfig *config) {
   osalDbgCheck(canp != NULL);
 
   osalSysLock();
-  osalDbgAssert((canp->state == CAN_STOP) ||
+  osalDbgAssert(canp->state == CAN_STOP, "invalid state");
-                (canp->state == CAN_STARTING) ||
+
-                (canp->state == CAN_READY),
+  /* Entering initialization mode. */
-                "invalid state");
+  canp->state = CAN_STARTING;
-  while (canp->state == CAN_STARTING) {
+  canp->config = config;
-    osalThreadSleepS((systime_t)1);
+
-  }
+  /* Low level initialization, could be a slow process and sleeps could
-  if (canp->state == CAN_STOP) {
+     be performed inside.*/
-    canp->config = config;
+  can_lld_start(canp);
-    can_lld_start(canp);
+
-    canp->state = CAN_READY;
+  /* The driver finally goes into the ready state.*/
-  }
+  canp->state = CAN_READY;
   osalSysUnlock();
 }
 
@@ -129,8 +129,13 @@ void canStop(CANDriver *canp) {
   osalSysLock();
   osalDbgAssert((canp->state == CAN_STOP) || (canp->state == CAN_READY),
                 "invalid state");
+
+  /* The low level driver is stopped.*/
   can_lld_stop(canp);
   canp->state  = CAN_STOP;
+
+  /* Threads waiting on CAN APIs are notified that the driver has been
+     stopped in order to not have stuck threads.*/
   osalThreadDequeueAllI(&canp->rxqueue, MSG_RESET);
   osalThreadDequeueAllI(&canp->txqueue, MSG_RESET);
   osalOsRescheduleS();