jtag: enable connect under reset

Currently if the target supports srst_nogate we wait until target assert_reset
until we get a chance to assert the srst.
However sometimes we will not get this far if the target has already failed
the jtag_examine_chain.

This has been tested on targets that support this behaviour (STM32 and STR9).

Change-Id: Ibcf7584b137b472f31ba6ddd5cd99d848c5508d1
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/971
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

diff --git a/src/jtag/core.c b/src/jtag/core.c
index 5d5803a3604a4c2350d72f5dfc19c82195801cf1..9f1e4cf03903fbe223473f7a0aec4b8cd1847386 100644 (file)
--- a/src/jtag/core.c
+++ b/src/jtag/core.c
@@ -1549,7 +1549,17 @@ int jtag_init_reset(struct command_context *cmd_ctx)
                if ((jtag_reset_config & RESET_SRST_PULLS_TRST) == 0)
                        jtag_add_reset(0, 1);
        }
-       jtag_add_reset(0, 0);
+
+       /* some targets enable us to connect with srst asserted */
+       if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
+               if (jtag_reset_config & RESET_SRST_NO_GATING)
+                       jtag_add_reset(0, 1);
+               else {
+                       LOG_WARNING("\'srst_nogate\' reset_config option is required");
+                       jtag_add_reset(0, 0);
+               }
+       } else
+               jtag_add_reset(0, 0);
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
                return retval;
@@ -1572,6 +1582,14 @@ int jtag_init(struct command_context *cmd_ctx)
 
        /* guard against oddball hardware: force resets to be inactive */
        jtag_add_reset(0, 0);
+
+       /* some targets enable us to connect with srst asserted */
+       if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
+               if (jtag_reset_config & RESET_SRST_NO_GATING)
+                       jtag_add_reset(0, 1);
+               else
+                       LOG_WARNING("\'srst_nogate\' reset_config option is required");
+       }
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
                return retval;