- added support for Intel/Marvel PXA27x (XScale) targets

- added support for scans coming from or ending in Shift-DR or Shift-IR to bitbang code (required for XScale debugging)
- cleaned up errror handlers. only use when there's a catchable error
- fix segfault when etm was configured without a valid driver



git-svn-id: svn://svn.berlios.de/openocd/trunk@176 b42882b7-edfa-0310-969c-e2dbd0fdcd60

9 files changed, 125 insertions, 127 deletions

diff --git a/src/jtag/bitbang.c b/src/jtag/bitbang.c
index 82e92a21..198a741f 100644
--- a/src/jtag/bitbang.c
+++ b/src/jtag/bitbang.c
@@ -132,21 +132,35 @@ void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 	enum tap_state saved_end_state = end_state;
 	int bit_cnt;
 	
-	if (ir_scan)
-		bitbang_end_state(TAP_SI);
-	else
-		bitbang_end_state(TAP_SD);
+	if (!((!ir_scan && (cur_state == TAP_SD)) || (ir_scan && (cur_state == TAP_SI))))
+	{
+		if (ir_scan)
+			bitbang_end_state(TAP_SI);
+		else
+			bitbang_end_state(TAP_SD);
 
-	bitbang_state_move();
-	bitbang_end_state(saved_end_state);
+		bitbang_state_move();
+		bitbang_end_state(saved_end_state);
+	}
 
 	for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 	{
+		/* set TMS high on the last bit unless we want to end in TAP_SD/SI */
+		int tms;
+		if ((ir_scan && (end_state == TAP_SI)) ||
+			(!ir_scan && (end_state == TAP_SD)))
+		{
+			tms = 0;
+		} else {
+			tms = (bit_cnt==scan_size-1) ? 1 : 0;
+		}
+		
 		/* if we're just reading the scan, but don't care about the output
 		 * default to outputting 'low', this also makes valgrind traces more readable,
 		 * as it removes the dependency on an uninitialised value
 		 */ 
-		if ((type != SCAN_IN) && ((buffer[bit_cnt/8] >> (bit_cnt % 8)) & 0x1)) {
+		if ((type != SCAN_IN) && ((buffer[bit_cnt/8] >> (bit_cnt % 8)) & 0x1))
+		{
 			bitbang_interface->write(0, (bit_cnt==scan_size-1) ? 1 : 0, 1);
 			bitbang_interface->write(1, (bit_cnt==scan_size-1) ? 1 : 0, 1);
 		} else {
diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index 6dfde760..98919123 100644
--- a/src/jtag/jtag.c
+++ b/src/jtag/jtag.c
@@ -58,6 +58,8 @@ static cmd_queue_page_t *cmd_queue_pages = NULL;
  * 3: Pause-DR
  * 4: Shift-IR
  * 5: Pause-IR
+ * 
+ * SD->SD and SI->SI have to be caught in interface specific code
  */
 u8 tap_move[6][6] =
 {
@@ -1086,9 +1088,6 @@ int jtag_read_buffer(u8 *buffer, scan_command_t *cmd)
 				
 				if (compare_failed)
 				{
-					char *captured_char = buf_to_str(captured, (num_bits > 64) ? 64 : num_bits, 16);
-					char *in_check_value_char = buf_to_str(cmd->fields[i].in_check_value, (num_bits > 64) ? 64 : num_bits, 16);
-
 					if (cmd->error_handler)
 					{
 						/* ask the error handler if once has been specified if this is a real problem */ 
@@ -1109,6 +1108,9 @@ int jtag_read_buffer(u8 *buffer, scan_command_t *cmd)
 					 */ 
 					if (compare_failed)
 					{
+						char *captured_char = buf_to_str(captured, (num_bits > 64) ? 64 : num_bits, 16);
+						char *in_check_value_char = buf_to_str(cmd->fields[i].in_check_value, (num_bits > 64) ? 64 : num_bits, 16);
+
 						if (cmd->fields[i].in_check_mask)
 						{
 							char *in_check_mask_char;
@@ -1120,10 +1122,11 @@ int jtag_read_buffer(u8 *buffer, scan_command_t *cmd)
 						{
 							WARNING("value captured during scan didn't pass the requested check: captured: 0x%s check_value: 0x%s", captured_char, in_check_value_char);
 						}
+
+						free(captured_char);
+						free(in_check_value_char);
 					}
 					
-					free(captured_char);
-					free(in_check_value_char);
 				}
 			}
 			free(captured);
diff --git a/src/jtag/jtag.h b/src/jtag/jtag.h
index 1464a080..1b03d615 100644
--- a/src/jtag/jtag.h
+++ b/src/jtag/jtag.h
@@ -59,6 +59,9 @@ extern tap_transition_t tap_transitions[16];	/* describe the TAP state diagram *
 extern enum tap_state end_state;		/* finish DR scans in dr_end_state */
 extern enum tap_state cur_state;		/* current TAP state */
 
+extern enum tap_state cmd_queue_end_state;		/* finish DR scans in dr_end_state */
+extern enum tap_state cmd_queue_cur_state;		/* current TAP state */
+
 #define TAP_MOVE(from, to) tap_move[tap_move_map[from]][tap_move_map[to]]
 
 typedef struct error_handler_s
diff --git a/src/target/arm7_9_common.c b/src/target/arm7_9_common.c
index 77a43fee..cda99d84 100644
--- a/src/target/arm7_9_common.c
+++ b/src/target/arm7_9_common.c
@@ -846,6 +846,13 @@ int arm7_9_prepare_reset_halt(target_t *target)
 	armv4_5_common_t *armv4_5 = target->arch_info;
 	arm7_9_common_t *arm7_9 = armv4_5->arch_info;
 	
+	/* poll the target, and resume if it was currently halted */
+	arm7_9_poll(target);
+	if (target->state == TARGET_HALTED)
+	{
+		arm7_9_resume(target, 1, 0x0, 0, 1);
+	}
+	
 	if (arm7_9->has_vector_catch)
 	{
 		/* program vector catch register to catch reset vector */
diff --git a/src/target/arm9tdmi.c b/src/target/arm9tdmi.c
index 7ecd1f0d..3b06b0e4 100644
--- a/src/target/arm9tdmi.c
+++ b/src/target/arm9tdmi.c
@@ -104,7 +104,7 @@ int arm9tdmi_jtag_error_handler(u8 *in_value, void *priv)
 	
 	DEBUG("caller: %s", caller);
 	
-	return ERROR_OK;
+	return ERROR_JTAG_QUEUE_FAILED;
 }
 
 int arm9tdmi_examine_debug_reason(target_t *target)
@@ -117,7 +117,6 @@ int arm9tdmi_examine_debug_reason(target_t *target)
 	if ((target->debug_reason != DBG_REASON_DBGRQ)
 			&& (target->debug_reason != DBG_REASON_SINGLESTEP))
 	{
-		error_handler_t error_handler;
 		scan_field_t fields[3];
 		u8 databus[4];
 		u8 instructionbus[4];
@@ -156,9 +155,7 @@ int arm9tdmi_examine_debug_reason(target_t *target)
 		fields[2].in_handler_priv = NULL;
 		
 		arm_jtag_scann(&arm7_9->jtag_info, 0x1);
-		error_handler.error_handler = arm9tdmi_jtag_error_handler;
-		error_handler.error_handler_priv = "arm9tdmi_examine_debug_reason";
-		arm_jtag_set_instr(&arm7_9->jtag_info, arm7_9->jtag_info.intest_instr, &error_handler);
+		arm_jtag_set_instr(&arm7_9->jtag_info, arm7_9->jtag_info.intest_instr, NULL);
 
 		jtag_add_dr_scan(3, fields, TAP_PD, NULL);
 		jtag_execute_queue();
@@ -187,7 +184,6 @@ int arm9tdmi_examine_debug_reason(target_t *target)
 /* put an instruction in the ARM9TDMI pipeline or write the data bus, and optionally read data */
 int arm9tdmi_clock_out(arm_jtag_t *jtag_info, u32 instr, u32 out, u32 *in, int sysspeed)
 {
-	error_handler_t error_handler;
 	scan_field_t fields[3];
 	u8 out_buf[4];
 	u8 instr_buf[4];
@@ -204,10 +200,7 @@ int arm9tdmi_clock_out(arm_jtag_t *jtag_info, u32 instr, u32 out, u32 *in, int s
 	jtag_add_end_state(TAP_PD);
 	arm_jtag_scann(jtag_info, 0x1);
 	
-	error_handler.error_handler = arm9tdmi_jtag_error_handler;
-	error_handler.error_handler_priv = "arm9tdmi_clock_out";
-	
-	arm_jtag_set_instr(jtag_info, jtag_info->intest_instr, &error_handler);
+	arm_jtag_set_instr(jtag_info, jtag_info->intest_instr, NULL);
 		
 	fields[0].device = jtag_info->chain_pos;
 	fields[0].num_bits = 32;
@@ -271,15 +264,11 @@ int arm9tdmi_clock_out(arm_jtag_t *jtag_info, u32 instr, u32 out, u32 *in, int s
 int arm9tdmi_clock_data_in(arm_jtag_t *jtag_info, u32 *in)
 {
 	scan_field_t fields[3];
-	error_handler_t error_handler;
 
 	jtag_add_end_state(TAP_PD);
 	arm_jtag_scann(jtag_info, 0x1);
 	
-	error_handler.error_handler = arm9tdmi_jtag_error_handler;
-	error_handler.error_handler_priv = "arm9tdmi_clock_data_in_endianness";
-	
-	arm_jtag_set_instr(jtag_info, jtag_info->intest_instr, &error_handler);
+	arm_jtag_set_instr(jtag_info, jtag_info->intest_instr, NULL);
 		
 	fields[0].device = jtag_info->chain_pos;
 	fields[0].num_bits = 32;
@@ -340,15 +329,11 @@ int arm9tdmi_clock_data_in(arm_jtag_t *jtag_info, u32 *in)
 int arm9tdmi_clock_data_in_endianness(arm_jtag_t *jtag_info, void *in, int size, int be)
 {
 	scan_field_t fields[3];
-	error_handler_t error_handler;
 	
 	jtag_add_end_state(TAP_PD);
 	arm_jtag_scann(jtag_info, 0x1);
 	
-	error_handler.error_handler = arm9tdmi_jtag_error_handler;
-	error_handler.error_handler_priv = "arm9tdmi_clock_data_in_endianness";
-	
-	arm_jtag_set_instr(jtag_info, jtag_info->intest_instr, &error_handler);
+	arm_jtag_set_instr(jtag_info, jtag_info->intest_instr, NULL);
 		
 	fields[0].device = jtag_info->chain_pos;
 	fields[0].num_bits = 32;
diff --git a/src/target/cortex_swjdp.c b/src/target/cortex_swjdp.c
index 15fc26da..e50c6843 100644
--- a/src/target/cortex_swjdp.c
+++ b/src/target/cortex_swjdp.c
@@ -54,26 +54,14 @@ are immediatley available.
  *                                                                         *
 ***************************************************************************/
 
-int swjdp_jtag_error_handler(u8 *in_value, void *priv)
-{
-	char *caller = priv;
-	
-	DEBUG("caller: %s", caller);
-	
-	return ERROR_OK;
-}
-
 /* Scan out and in from target ordered u8 buffers */
 int swjdp_scan(arm_jtag_t *jtag_info, u8 chain, u8 reg_addr, u8 RnW, u8 *outvalue, u8 *invalue, u8 *ack)
 {
 	scan_field_t fields[2];
 	u8 out_addr_buf;
-	error_handler_t error_handler;
 	
 	jtag_add_end_state(TAP_RTI);
-	error_handler.error_handler = swjdp_jtag_error_handler;
-	error_handler.error_handler_priv = "swjdp_scan";
-	arm_jtag_set_instr(jtag_info, chain, &error_handler);
+	arm_jtag_set_instr(jtag_info, chain, NULL);
 
 	fields[0].device = jtag_info->chain_pos;
 	fields[0].num_bits = 3;
@@ -108,12 +96,9 @@ int swjdp_scan_u32(arm_jtag_t *jtag_info, u8 chain, u8 reg_addr, u8 RnW, u32 out
 	scan_field_t fields[2];
 	u8 out_value_buf[4];
 	u8 out_addr_buf;
-	error_handler_t error_handler;
 	
 	jtag_add_end_state(TAP_RTI);
-	error_handler.error_handler = swjdp_jtag_error_handler;
-	error_handler.error_handler_priv = "swjdp_scan_u32";
-	arm_jtag_set_instr(jtag_info, chain, &error_handler);
+	arm_jtag_set_instr(jtag_info, chain, NULL);
 
 	fields[0].device = jtag_info->chain_pos;
 	fields[0].num_bits = 3;
diff --git a/src/target/embeddedice.c b/src/target/embeddedice.c
index ef38e136..f601c1eb 100644
--- a/src/target/embeddedice.c
+++ b/src/target/embeddedice.c
@@ -86,15 +86,6 @@ int embeddedice_set_reg_w_exec(reg_t *reg, u8 *buf);
 int embeddedice_write_reg(reg_t *reg, u32 value);
 int embeddedice_read_reg(reg_t *reg);
 
-int embeddedice_jtag_error_handler(u8 *in_value, void *priv)
-{
-	char *caller = priv;
-	
-	DEBUG("caller: %s", caller);
-	
-	return ERROR_OK;
-}
-
 reg_cache_t* embeddedice_build_reg_cache(target_t *target, arm7_9_common_t *arm7_9)
 {
 	reg_cache_t *reg_cache = malloc(sizeof(reg_cache_t));
@@ -223,17 +214,13 @@ int embeddedice_read_reg_w_check(reg_t *reg, u8* check_value, u8* check_mask)
 	embeddedice_reg_t *ice_reg = reg->arch_info;
 	u8 reg_addr = ice_reg->addr & 0x1f;
 	scan_field_t fields[3];
-	error_handler_t error_handler;
 	
 	DEBUG("%i", ice_reg->addr);
 
 	jtag_add_end_state(TAP_RTI);
 	arm_jtag_scann(ice_reg->jtag_info, 0x2);
 	
-	error_handler.error_handler = embeddedice_jtag_error_handler;
-	error_handler.error_handler_priv = "embeddedice_read_reg_w_check";
-	
-	arm_jtag_set_instr(ice_reg->jtag_info, ice_reg->jtag_info->intest_instr, &error_handler);
+	arm_jtag_set_instr(ice_reg->jtag_info, ice_reg->jtag_info->intest_instr, NULL);
 	
 	fields[0].device = ice_reg->jtag_info->chain_pos;
 	fields[0].num_bits = 32;
@@ -324,16 +311,12 @@ int embeddedice_write_reg(reg_t *reg, u32 value)
 	embeddedice_reg_t *ice_reg = reg->arch_info;
 	u8 reg_addr = ice_reg->addr & 0x1f;
 	scan_field_t fields[3];
-	error_handler_t error_handler;
 	
 	DEBUG("%i: 0x%8.8x", ice_reg->addr, value);
 	
 	jtag_add_end_state(TAP_RTI);
 	arm_jtag_scann(ice_reg->jtag_info, 0x2);
 	
-	error_handler.error_handler = embeddedice_jtag_error_handler;
-	error_handler.error_handler_priv = "embeddedice_write_reg";
-	
 	arm_jtag_set_instr(ice_reg->jtag_info, ice_reg->jtag_info->intest_instr, NULL);
 	
 	fields[0].device = ice_reg->jtag_info->chain_pos;
diff --git a/src/target/etm.c b/src/target/etm.c
index dd6e6025..b4c20750 100644
--- a/src/target/etm.c
+++ b/src/target/etm.c
@@ -1231,6 +1231,14 @@ int handle_etm_config_command(struct command_context_s *cmd_ctx, char *cmd, char
 		}
 	}
 	
+	if (!etm_capture_drivers[i])
+	{
+		/* no supported capture driver found, don't register an ETM */
+		free(etm_ctx);
+		ERROR("trace capture driver '%s' not found", args[4]);
+		return ERROR_OK;
+	}
+	
 	etm_ctx->target = target;
 	etm_ctx->trace_data = NULL;
 	etm_ctx->trace_depth = 0;
diff --git a/src/target/xscale.c b/src/target/xscale.c
index 311e53bc..2cfc23e7 100644
--- a/src/target/xscale.c
+++ b/src/target/xscale.c
@@ -1,5 +1,5 @@
 /***************************************************************************
- *   Copyright (C) 2006 by Dominic Rath                                    *
+ *   Copyright (C) 2006, 2007 by Dominic Rath                              *
  *   Dominic.Rath@gmx.de                                                   *
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
@@ -34,15 +34,16 @@
 #include "binarybuffer.h"
 #include "time_support.h"
 #include "breakpoints.h"
+#include "fileio.h"
 
 #include <stdlib.h>
 #include <string.h>
 
 #include <sys/types.h>
-#include <sys/stat.h>
 #include <unistd.h>
 #include <errno.h>
 
+
 /* cli handling */
 int xscale_register_commands(struct command_context_s *cmd_ctx);
 
@@ -1197,9 +1198,6 @@ int xscale_halt(target_t *target)
 	else if (target->state == TARGET_RESET)
 	{
 		DEBUG("target->state == TARGET_RESET");
-		
-		/* clear TRST */
-		jtag_add_reset(0, -1);
 	}
 	else
 	{
@@ -1517,22 +1515,32 @@ int xscale_assert_reset(target_t *target)
 	xscale_common_t *xscale = armv4_5->arch_info;
 	
 	DEBUG("target->state: %s", target_state_strings[target->state]);
+
+	/* select DCSR instruction (set endstate to R-T-I to ensure we don't 
+	 * end up in T-L-R, which would reset JTAG
+	 */ 
+	jtag_add_end_state(TAP_RTI);
+	xscale_jtag_set_instr(xscale->jtag_info.chain_pos, xscale->jtag_info.dcsr);
 	
-	/* if the handler isn't installed yet, we have to assert TRST, too */
-	if (!xscale->handler_installed)
-	{
-		jtag_add_reset(1, 1);
-	}
-	else
-		jtag_add_reset(-1, 1);
+	/* set Hold reset, Halt mode and Trap Reset */
+	buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 30, 1, 0x1);
+	buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 16, 1, 0x1);
+	xscale_write_dcsr(target, 1, 0);
+
+	/* select BYPASS, because having DCSR selected caused problems on the PXA27x */
+	xscale_jtag_set_instr(xscale->jtag_info.chain_pos, 0x7f);
+	jtag_execute_queue();
+		
+	/* assert reset */	
+	jtag_add_reset(0, 1);
 	
 	/* sleep 1ms, to be sure we fulfill any requirements */
 	jtag_add_sleep(1000);
+	jtag_execute_queue();
 	
 	target->state = TARGET_RESET;
 	
 	return ERROR_OK;
-
 }
 
 int xscale_deassert_reset(target_t *target)
@@ -1540,17 +1548,18 @@ int xscale_deassert_reset(target_t *target)
 	armv4_5_common_t *armv4_5 = target->arch_info;
 	xscale_common_t *xscale = armv4_5->arch_info;
 	
-	FILE *binary;
+	fileio_t debug_handler;
 	u32 address;
-	struct stat binary_stat;
 	u32 binary_size;
 
-	u32 buffer[8];
 	u32 buf_cnt;
 	int i;
+	int retval;
 	
 	breakpoint_t *breakpoint = target->breakpoints;
 	
+	DEBUG("-");
+	
 	xscale->ibcr_available = 2;
 	xscale->ibcr0_used = 0;
 	xscale->ibcr1_used = 0;
@@ -1571,42 +1580,27 @@ int xscale_deassert_reset(target_t *target)
 	
 	if (!xscale->handler_installed)
 	{
-		/* release TRST */
-		jtag_add_reset(0, -1);
-		jtag_add_sleep(100000);
-		
-		/* set Hold reset, Halt mode and Trap Reset */
-		buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 30, 1, 0x1);
-		buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 16, 1, 0x1);
-		xscale_write_dcsr(target, 1, 0);
-		jtag_add_runtest(100, TAP_RTI);
-		jtag_execute_queue();
-		
 		/* release SRST */
 		jtag_add_reset(0, 0);
-		/* wait 150ms; 100ms were not enough */
-		jtag_add_sleep(150000);
+		
+		/* wait 300ms; 150 and 100ms were not enough */
+		jtag_add_sleep(3000000);
 
 		jtag_add_runtest(2030, TAP_RTI);
 		jtag_execute_queue();
-		
+
+		/* set Hold reset, Halt mode and Trap Reset */
+		buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 30, 1, 0x1);
+		buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 16, 1, 0x1);
 		xscale_write_dcsr(target, 1, 0);
-		jtag_execute_queue();
-		
-		/* TODO: load debug handler */
-		if (stat("target/xscale/debug_handler.bin", &binary_stat) == -1)
-		{
-			ERROR("couldn't stat() target/xscale/debug_handler.bin: %s",  strerror(errno));
-			return ERROR_OK;
-		}
-		
-		if (!(binary = fopen("target/xscale/debug_handler.bin", "r")))
+
+		if (fileio_open(&debug_handler, "target/xscale/debug_handler.bin", FILEIO_READ, FILEIO_BINARY) != ERROR_OK)
 		{
-			ERROR("couldn't open target/xscale/debug_handler.bin: %s", strerror(errno));
+			ERROR("file open error: %s", debug_handler.error_str);
 			return ERROR_OK;
 		}
-		
-		if ((binary_size = binary_stat.st_size) % 4)
+	
+		if ((binary_size = debug_handler.size) % 4)
 		{
 			ERROR("debug_handler.bin: size not a multiple of 4");
 			exit(-1);
@@ -1623,41 +1617,51 @@ int xscale_deassert_reset(target_t *target)
 		address = xscale->handler_address;
 		while (binary_size > 0)
 		{
-			buf_cnt = fread(buffer, 4, 8, binary);
+			u32 cache_line[8];
+			u8 buffer[32];
+			
+			if ((retval = fileio_read(&debug_handler, 32, buffer, &buf_cnt)) != ERROR_OK)
+			{
+				ERROR("reading debug handler failed: %s", debug_handler.error_str);
+			}
 			
-			for (i = 0; i < buf_cnt; i++)
+			for (i = 0; i < buf_cnt; i += 4)
 			{
 				/* convert LE buffer to host-endian u32 */
-				buffer[i] = buf_get_u32((u8*)(&buffer[i]), 0, 32);
+				cache_line[i / 4] = le_to_h_u32(&buffer[i]);
 			}
 			
-			if (buf_cnt < 8)
+			for (; buf_cnt < 32; buf_cnt += 4)
 			{
-				for (; buf_cnt < 8; buf_cnt++)
-				{
-					buffer[buf_cnt] = 0xe1a08008;
-				}
+					cache_line[buf_cnt / 4] = 0xe1a08008;
 			}
 			
 			/* only load addresses other than the reset vectors */
 			if ((address % 0x400) != 0x0)
 			{
-				xscale_load_ic(target, 1, address, buffer);
+				xscale_load_ic(target, 1, address, cache_line);
 			}
 			
-			address += buf_cnt * 4;
-			binary_size -= buf_cnt * 4;
+			address += buf_cnt;
+			binary_size -= buf_cnt;
 		};
 		
 		xscale_load_ic(target, 1, 0x0, xscale->low_vectors);
 		xscale_load_ic(target, 1, 0xffff0000, xscale->high_vectors);
 	
 		jtag_add_runtest(30, TAP_RTI);
+
+		jtag_add_sleep(100000);
 		
-		/* let the target run (should enter debug handler) */
-		xscale_write_dcsr(target, 0, 0);
+		/* set Hold reset, Halt mode and Trap Reset */
+		buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 30, 1, 0x1);
+		buf_set_u32(xscale->reg_cache->reg_list[XSCALE_DCSR].value, 16, 1, 0x1);
+		xscale_write_dcsr(target, 1, 0);
+
+		/* clear Hold reset to let the target run (should enter debug handler) */
+		xscale_write_dcsr(target, 0, 1);
 		target->state = TARGET_RUNNING;
-		
+
 		if ((target->reset_mode != RESET_HALT) && (target->reset_mode != RESET_INIT))
 		{
 			jtag_add_sleep(10000);
@@ -1666,8 +1670,8 @@ int xscale_deassert_reset(target_t *target)
 			xscale_debug_entry(target);
 			target->state = TARGET_HALTED;
 			
-			/* the PC is now at 0x0 */
-			buf_set_u32(armv4_5->core_cache->reg_list[15].value, 0, 32, 0x0);
+			/* resume the target */
+			xscale_resume(target, 1, 0x0, 1, 0);
 		}
 	}
 	else
@@ -1687,7 +1691,9 @@ int xscale_soft_reset_halt(struct target_s *target)
 
 int xscale_prepare_reset_halt(struct target_s *target)
 {
-	/* nothing to be done for reset_halt on XScale targets */
+	/* nothing to be done for reset_halt on XScale targets
+	 * we always halt after a reset to upload the debug handler
+	 */
 	return ERROR_OK;
 }
 
@@ -2584,6 +2590,10 @@ int xscale_init_target(struct command_context_s *cmd_ctx, struct target_s *targe
 		ERROR("Reset target to enable debug");
 	}
 	
+	/* assert TRST once during startup */
+	jtag_add_reset(1, 0);
+	jtag_add_reset(0, 0);
+	
 	return ERROR_OK;
 }