David Brownell <david-b@pacbell.net> More jtag_add_reset() cleanup:

Unify the handling of the req_srst parameter, and rip out a
large NOP branch and its associated FIXME.  (There didn't seem
to be anything that needs fixing; but that was unclear since
the constraints were scattered all over the place not unified.)

git-svn-id: svn://svn.berlios.de/openocd/trunk@2623 b42882b7-edfa-0310-969c-e2dbd0fdcd60

diff --git a/src/jtag/core.c b/src/jtag/core.c
index 611ea7d6596de74fb62bbee5c1478c63ecfa6034..d278c96bcca83346f58245ca151889d0ebfec06c 100644 (file)
--- a/src/jtag/core.c
+++ b/src/jtag/core.c
@@ -585,9 +585,31 @@ void jtag_add_clocks(int num_cycles)
 void jtag_add_reset(int req_tlr_or_trst, int req_srst)
 {
        int trst_with_tlr = 0;
-       int new_srst;
+       int new_srst = 0;
        int new_trst = 0;
 
+       /* Without SRST, we must use target-specific JTAG operations
+        * on each target; callers should not be requesting SRST when
+        * that signal doesn't exist.
+        *
+        * RESET_SRST_PULLS_TRST is a board or chip level quirk, which
+        * can kick in even if the JTAG adapter can't drive TRST.
+        */
+       if (req_srst) {
+               if (!(jtag_reset_config & RESET_HAS_SRST)) {
+                       LOG_ERROR("BUG: can't assert SRST");
+                       jtag_set_error(ERROR_FAIL);
+                       return;
+               }
+               if ((jtag_reset_config & RESET_SRST_PULLS_TRST) != 0
+                               && !req_tlr_or_trst) {
+                       LOG_ERROR("BUG: can't assert only SRST");
+                       jtag_set_error(ERROR_FAIL);
+                       return;
+               }
+               new_srst = 1;
+       }
+
        /* JTAG reset (entry to TAP_RESET state) can always be achieved
         * using TCK and TMS; that may go through a TAP_{IR,DR}UPDATE
         * state first.  TRST accelerates it, and bypasses those states.
@@ -605,41 +627,6 @@ void jtag_add_reset(int req_tlr_or_trst, int req_srst)
                        new_trst = 1;
        }
 
-       /* FIX!!! there are *many* different cases here. A better
-        * approach is needed for legal combinations of transitions...
-        */
-       if ((jtag_reset_config & RESET_HAS_SRST)&&
-                       (jtag_reset_config & RESET_HAS_TRST)&&
-                       ((jtag_reset_config & RESET_SRST_PULLS_TRST) == 0))
-       {
-               if (((req_tlr_or_trst&&!jtag_trst)||
-                               (!req_tlr_or_trst && jtag_trst))&&
-                               ((req_srst&&!jtag_srst)||
-                                               (!req_srst && jtag_srst)))
-               {
-                       /* FIX!!! srst_pulls_trst allows 1,1 => 0,0 transition.... */
-                       //LOG_ERROR("BUG: transition of req_tlr_or_trst and req_srst in the same jtag_add_reset() call is undefined");
-               }
-       }
-
-       /* Make sure that jtag_reset_config allows the requested reset */
-       /* if SRST pulls TRST, we can't fulfill srst == 1 with trst == 0 */
-       if (((jtag_reset_config & RESET_SRST_PULLS_TRST) && (req_srst == 1)) && (!req_tlr_or_trst))
-       {
-               LOG_ERROR("BUG: requested reset would assert trst");
-               jtag_set_error(ERROR_FAIL);
-               return;
-       }
-
-       if (req_srst && !(jtag_reset_config & RESET_HAS_SRST))
-       {
-               LOG_ERROR("BUG: requested SRST assertion, but the current configuration doesn't support this");
-               jtag_set_error(ERROR_FAIL);
-               return;
-       }
-
-       new_srst = req_srst;
-
        /* Maybe change TRST and/or SRST signal state */
        if (jtag_srst != new_srst || jtag_trst != new_trst) {
                int retval;