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

Make the TCL "drscan" and "irscan" commands finish in RUN/IDLE
unless the user specifies otherwise ... usually they'd choose
something like DRPAUSE or IRPAUSE, avoiding RUN/IDLE.

The current "end" state is whatever the preceding commands left
in "cmd_queue_end_state", which to TCL scripts isn't knowable.
This change should forestall various surprises/bugs.

Also check that any "end" state specified is safe in case this
adapter's JTAG clock is free-running.  For now, just issue a
warning; eventually a hard failure is probably correct.

git-svn-id: svn://svn.berlios.de/openocd/trunk@1988 b42882b7-edfa-0310-969c-e2dbd0fdcd60

diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index fb7429f267d0e855342d4a9fe6f1cf2d5433a27f..ec233086a0a537f9c84852c3931dcb2c481306fd 100644 (file)
--- a/src/jtag/jtag.c
+++ b/src/jtag/jtag.c
@@ -2955,6 +2955,26 @@ static int handle_runtest_command(struct command_context_s *cmd_ctx, char *cmd,
 
 }
 
+/*
+ * For "irscan" or "drscan" commands, the "end" (really, "next") state
+ * should be stable ... and *NOT* a shift state, otherwise free-running
+ * jtag clocks could change the values latched by the update state.
+ */
+static bool scan_is_safe(tap_state_t state)
+{
+       switch (state)
+       {
+       case TAP_RESET:
+       case TAP_IDLE:
+       case TAP_DRPAUSE:
+       case TAP_IRPAUSE:
+               return true;
+       default:
+               return false;
+       }
+}
+
+
 static int handle_irscan_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
        int i;
@@ -2967,11 +2987,12 @@ static int handle_irscan_command(struct command_context_s *cmd_ctx, char *cmd, c
                return ERROR_COMMAND_SYNTAX_ERROR;
        }
 
-       /* optional "-endstate" */
-       /*          "statename" */
-       /* at the end of the arguments. */
-       /* assume none. */
-       endstate = cmd_queue_end_state;
+       /* optional "-endstate" "statename" at the end of the arguments,
+        * so that e.g. IRPAUSE can let us load the data register before
+        * entering RUN/IDLE to execute the instruction we load here.
+        */
+       endstate = TAP_IDLE;
+
        if( argc >= 4 ){
                /* have at least one pair of numbers. */
                /* is last pair the magic text? */
@@ -2988,6 +3009,9 @@ static int handle_irscan_command(struct command_context_s *cmd_ctx, char *cmd, c
                        if( endstate >= TAP_NUM_STATES ){
                                return ERROR_COMMAND_SYNTAX_ERROR;
                        } else {
+                               if (!scan_is_safe(endstate))
+                                       LOG_WARNING("irscan with unsafe "
+                                                       "endstate \"%s\"", cpA);
                                /* found - remove the last 2 args */
                                argc -= 2;
                        }
@@ -3052,8 +3076,8 @@ static int Jim_Command_drscan(Jim_Interp *interp, int argc, Jim_Obj *const *args
                return JIM_ERR;
        }
 
-       /* assume no endstate */
-       endstate = cmd_queue_end_state;
+       endstate = TAP_IDLE;
+
        /* validate arguments as numbers */
        e = JIM_OK;
        for (i = 2; i < argc; i+=2)
@@ -3073,7 +3097,10 @@ static int Jim_Command_drscan(Jim_Interp *interp, int argc, Jim_Obj *const *args
                        return e;
                }
 
-               /* it could be: "-endstate FOO" */
+               /* it could be: "-endstate FOO"
+                * e.g. DRPAUSE so we can issue more instructions
+                * before entering RUN/IDLE and executing them.
+                */
 
                /* get arg as a string. */
                cp = Jim_GetString( args[i], NULL );
@@ -3088,6 +3115,10 @@ static int Jim_Command_drscan(Jim_Interp *interp, int argc, Jim_Obj *const *args
                                /* update the error message */
                                Jim_SetResult_sprintf(interp,"endstate: %s invalid", cp );
                        } else {
+                               if (!scan_is_safe(endstate))
+                                       LOG_WARNING("drscan with unsafe "
+                                                       "endstate \"%s\"", cp);
+
                                /* valid - so clear the error */
                                e = JIM_OK;
                                /* and remove the last 2 args */