David Brownell <david-b@pacbell.net>:

Extend the internal JTAG event handlers to cover enable/disable,
and use those events to make sure that targets get "examined" if
they were disabled when the scan chain was first set up:

 - Remove "enum jtag_tap_event", merge with "enum jtag_event",
   so C code can now listen for TAP enable/disable events.

 - Report those events so they can trigger callbacks.

 - During startup, make target_examine() register a handler to
   catch ENABLE events for any then-disabled targets.

This fixes bugs like "can't halt target after enabling its TAP".

One class of unresolved bugs:  if the target has an ETM hooked
up to an ETB, nothing activates the ETB.  But starting up the
ETM without access to the ETB registers fails...


git-svn-id: svn://svn.berlios.de/openocd/trunk@2251 b42882b7-edfa-0310-969c-e2dbd0fdcd60

src/jtag/core.c

@@ -61,6 +61,8 @@ static int jtag_error = ERROR_OK;
 static const char *jtag_event_strings[] =
 {
 	[JTAG_TRST_ASSERTED] = "JTAG controller reset (RESET or TRST)",
+	[JTAG_TAP_EVENT_ENABLE] = "TAP enabled",
+	[JTAG_TAP_EVENT_DISABLE] = "TAP disabled",
 };
 
 static int jtag_trst = 0;

src/jtag/jtag.h

@@ -201,19 +201,18 @@ extern unsigned jtag_tap_count(void);
  * - SRST pulls TRST
  * - TRST asserted
  *
- **/
+ * TAP activation/deactivation is currently implemented outside the core
+ * using scripted code that understands the specific router type.
+ */
 enum jtag_event {
-	JTAG_TRST_ASSERTED
-};
-
-enum jtag_tap_event {
+	JTAG_TRST_ASSERTED,
 	JTAG_TAP_EVENT_ENABLE,
-	JTAG_TAP_EVENT_DISABLE
+	JTAG_TAP_EVENT_DISABLE,
 };
 
 struct jtag_tap_event_action_s
 {
-	enum jtag_tap_event      event;
+	enum jtag_event		event;
 	Jim_Obj*                 body;
 	jtag_tap_event_action_t* next;
 };

src/jtag/tcl.c

@@ -256,7 +256,7 @@ static int jtag_tap_configure_cmd( Jim_GetOptInfo *goi, jtag_tap_t * tap)
 					jteap = tap->event_action;
 					/* replace existing? */
 					while (jteap) {
-						if (jteap->event == (enum jtag_tap_event)n->value) {
+						if (jteap->event == (enum jtag_event)n->value) {
 							break;
 						}
 						jteap = jteap->next;
@@ -460,7 +460,7 @@ static int jim_newtap_cmd( Jim_GetOptInfo *goi )
 	return JIM_ERR;
 }
 
-static void jtag_tap_handle_event( jtag_tap_t * tap, enum jtag_tap_event e)
+static void jtag_tap_handle_event(jtag_tap_t *tap, enum jtag_event e)
 {
 	jtag_tap_event_action_t * jteap;
 	int done;
@@ -594,6 +594,8 @@ static int jim_jtag_command( Jim_Interp *interp, int argc, Jim_Obj *const *argv
 				 *  - scan chain length grew by one (this)
 				 *  - IDs and IR lengths are as expected
 				 */
+
+				jtag_call_event_callbacks(JTAG_TAP_EVENT_ENABLE);
 				break;
 			case JTAG_CMD_TAPDISABLE:
 				if (!t->enabled)
@@ -606,6 +608,8 @@ static int jim_jtag_command( Jim_Interp *interp, int argc, Jim_Obj *const *argv
 				 *  - scan chain length shrank by one (this)
 				 *  - IDs and IR lengths are as expected
 				 */
+
+				jtag_call_event_callbacks(JTAG_TAP_EVENT_DISABLE);
 				break;
 			}
 			e = t->enabled;

src/target/target.c

@@ -478,6 +478,18 @@ int target_examine_one(struct target_s *target)
 	return target->type->examine(target);
 }
 
+static int jtag_enable_callback(enum jtag_event event, void *priv)
+{
+	target_t *target = priv;
+
+	if (event != JTAG_TAP_EVENT_ENABLE || !target->tap->enabled)
+		return ERROR_OK;
+
+	jtag_unregister_event_callback(jtag_enable_callback, target);
+	return target_examine_one(target);
+}
+
+
 /* Targets that correctly implement init+examine, i.e.
  * no communication with target during init:
  *
@@ -490,8 +502,12 @@ int target_examine(void)
 
 	for (target = all_targets; target; target = target->next)
 	{
-		if (!target->tap->enabled)
+		/* defer examination, but don't skip it */
+		if (!target->tap->enabled) {
+			jtag_register_event_callback(jtag_enable_callback,
+					target);
 			continue;
+		}
 		if ((retval = target_examine_one(target)) != ERROR_OK)
 			return retval;
 	}