Updates for "reset_config":

 - revert to previous default: don't talk JTAG during SRST
 - add "srst_nogates" flag, the converse of "srst_gates_jtag"
 - with no args, display the current configuration

And update the User's Guide text with bullet lists to be a bit more clear.


git-svn-id: svn://svn.berlios.de/openocd/trunk@2818 b42882b7-edfa-0310-969c-e2dbd0fdcd60

3 files changed, 106 insertions, 18 deletions

diff --git a/src/jtag/jtag.h b/src/jtag/jtag.h
index 786b2b83..60774589 100644
--- a/src/jtag/jtag.h
+++ b/src/jtag/jtag.h
@@ -286,7 +286,7 @@ enum reset_types {
 	RESET_TRST_PULLS_SRST = 0x8,
 	RESET_TRST_OPEN_DRAIN = 0x10,
 	RESET_SRST_PUSH_PULL  = 0x20,
-	RESET_SRST_GATES_JTAG = 0x40,
+	RESET_SRST_NO_GATING  = 0x40,
 };
 
 enum reset_types jtag_get_reset_config(void);
diff --git a/src/jtag/tcl.c b/src/jtag/tcl.c
index 9101d31e..e080279a 100644
--- a/src/jtag/tcl.c
+++ b/src/jtag/tcl.c
@@ -631,7 +631,12 @@ int jtag_register_commands(struct command_context_s *cmd_ctx)
 		COMMAND_CONFIG, "(DEPRECATED) jtag_device <ir_length> <ir_expected> <ir_mask>");
 	register_command(cmd_ctx, NULL, "reset_config", handle_reset_config_command,
 		COMMAND_ANY,
-		"[none/trst_only/srst_only/trst_and_srst] [srst_pulls_trst/trst_pulls_srst] [combined/separate] [trst_push_pull/trst_open_drain] [srst_push_pull/srst_open_drain]");
+		"reset_config "
+		"[none|trst_only|srst_only|trst_and_srst] "
+		"[srst_pulls_trst|trst_pulls_srst|combined|separate] "
+		"[srst_gates_jtag|srst_nogate] "
+		"[trst_push_pull|trst_open_drain] "
+		"[srst_push_pull|srst_open_drain]");
 	register_command(cmd_ctx, NULL, "jtag_nsrst_delay", handle_jtag_nsrst_delay_command,
 		COMMAND_ANY, "jtag_nsrst_delay <ms> - delay after deasserting srst in ms");
 	register_command(cmd_ctx, NULL, "jtag_ntrst_delay", handle_jtag_ntrst_delay_command,
@@ -851,9 +856,6 @@ static int handle_reset_config_command(struct command_context_s *cmd_ctx, char *
 	int new_cfg = 0;
 	int mask = 0;
 
-	if (argc < 1)
-		return ERROR_COMMAND_SYNTAX_ERROR;
-
 	/* Original versions cared about the order of these tokens:
 	 *   reset_config signals [combination [trst_type [srst_type]]]
 	 * They also clobbered the previous configuration even on error.
@@ -865,13 +867,21 @@ static int handle_reset_config_command(struct command_context_s *cmd_ctx, char *
 		int tmp = 0;
 		int m;
 
-		m = RESET_SRST_GATES_JTAG;
-		tmp = 0;
+		/* gating */
+		m = RESET_SRST_NO_GATING;
 		if (strcmp(*args, "srst_gates_jtag") == 0)
-		{
-			tmp = RESET_SRST_GATES_JTAG;
-			goto next;
+			/* default: don't use JTAG while SRST asserted */;
+		else if (strcmp(*args, "srst_nogate") == 0)
+			tmp = RESET_SRST_NO_GATING;
+		else
+			m = 0;
+		if (mask & m) {
+			LOG_ERROR("extra reset_config %s spec (%s)",
+					"gating", *args);
+			return ERROR_INVALID_ARGUMENTS;
 		}
+		if (m)
+			goto next;
 
 		/* signals */
 		m = RESET_HAS_TRST | RESET_HAS_SRST;
@@ -958,10 +968,81 @@ next:
 	}
 
 	/* clear previous values of those bits, save new values */
-	enum reset_types old_cfg = jtag_get_reset_config();
-	old_cfg &= ~mask;
-	new_cfg |= old_cfg;
-	jtag_set_reset_config(new_cfg);
+	if (mask) {
+		int old_cfg = jtag_get_reset_config();
+
+		old_cfg &= ~mask;
+		new_cfg |= old_cfg;
+		jtag_set_reset_config(new_cfg);
+	} else
+		new_cfg = jtag_get_reset_config();
+
+
+	/*
+	 * Display the (now-)current reset mode
+	 */
+	char *modes[5];
+
+	/* minimal JTAG has neither SRST nor TRST (so that's the default) */
+	switch (new_cfg & (RESET_HAS_TRST | RESET_HAS_SRST)) {
+	case RESET_HAS_SRST:
+		modes[0] = "srst_only";
+		break;
+	case RESET_HAS_TRST:
+		modes[0] = "trst_only";
+		break;
+	case RESET_TRST_AND_SRST:
+		modes[0] = "trst_and_srst";
+		break;
+	default:
+		modes[0] = "none";
+		break;
+	}
+
+	/* normally SRST and TRST are decoupled; but bugs happen ... */
+	switch (new_cfg & (RESET_SRST_PULLS_TRST | RESET_TRST_PULLS_SRST)) {
+	case RESET_SRST_PULLS_TRST:
+		modes[1] = "srst_pulls_trst";
+		break;
+	case RESET_TRST_PULLS_SRST:
+		modes[1] = "trst_pulls_srst";
+		break;
+	case RESET_SRST_PULLS_TRST | RESET_TRST_PULLS_SRST:
+		modes[1] = "combined";
+		break;
+	default:
+		modes[1] = "separate";
+		break;
+	}
+
+	/* TRST-less connectors include Altera, Xilinx, and minimal JTAG */
+	if (new_cfg & RESET_HAS_TRST) {
+		if (new_cfg & RESET_TRST_OPEN_DRAIN)
+			modes[3] = " trst_open_drain";
+		else
+			modes[3] = " trst_push_pull";
+	} else
+		modes[3] = "";
+
+	/* SRST-less connectors include TI-14, Xilinx, and minimal JTAG */
+	if (new_cfg & RESET_HAS_SRST) {
+		if (new_cfg & RESET_SRST_NO_GATING)
+			modes[2] = " srst_nogate";
+		else
+			modes[2] = " srst_gates_jtag";
+
+		if (new_cfg & RESET_SRST_PUSH_PULL)
+			modes[4] = " srst_push_pull";
+		else
+			modes[4] = " srst_open_drain";
+	} else {
+		modes[2] = "";
+		modes[4] = "";
+	}
+
+	command_print(cmd_ctx, "%s %s%s%s%s",
+			modes[0], modes[1],
+			modes[2], modes[3], modes[4]);
 
 	return ERROR_OK;
 }
diff --git a/src/target/arm7_9_common.c b/src/target/arm7_9_common.c
index 40dddda6..2b064f23 100644
--- a/src/target/arm7_9_common.c
+++ b/src/target/arm7_9_common.c
@@ -1021,12 +1021,19 @@ int arm7_9_assert_reset(target_t *target)
 		return ERROR_FAIL;
 	}
 
-	/* at this point trst has been asserted/deasserted once. We want to
-	 * program embedded ice while SRST is asserted, but some CPUs gate
-	 * the JTAG clock while SRST is asserted
+	/* At this point trst has been asserted/deasserted once. We would
+	 * like to program EmbeddedICE while SRST is asserted, instead of
+	 * depending on SRST to leave that module alone.  However, many CPUs
+	 * gate the JTAG clock while SRST is asserted; or JTAG may need
+	 * clock stability guarantees (adaptive clocking might help).
+	 *
+	 * So we assume JTAG access during SRST is off the menu unless it's
+	 * been specifically enabled.
 	 */
 	bool srst_asserted = false;
-	if (((jtag_reset_config & RESET_SRST_PULLS_TRST) == 0) && ((jtag_reset_config & RESET_SRST_GATES_JTAG) == 0))
+
+	if (((jtag_reset_config & RESET_SRST_PULLS_TRST) == 0)
+			&& (jtag_reset_config & RESET_SRST_NO_GATING))
 	{
 		jtag_add_reset(0, 1);
 		srst_asserted = true;