jtag_get_device() now returns NULL and reports error instead of invoking exit()

git-svn-id: svn://svn.berlios.de/openocd/trunk@1176 b42882b7-edfa-0310-969c-e2dbd0fdcd60

11 files changed, 394 insertions, 352 deletions

diff --git a/src/flash/str9xpec.c b/src/flash/str9xpec.c
index cefa2d9..c01292d 100644
--- a/src/flash/str9xpec.c
+++ b/src/flash/str9xpec.c
@@ -84,7 +84,7 @@ flash_driver_t str9xpec_flash =
 int str9xpec_register_commands(struct command_context_s *cmd_ctx)
 {
 	command_t *str9xpec_cmd = register_command(cmd_ctx, NULL, "str9xpec", NULL, COMMAND_ANY, "str9xpec flash specific commands");
-	
+
 	register_command(cmd_ctx, str9xpec_cmd, "enable_turbo", str9xpec_handle_flash_enable_turbo_command, COMMAND_EXEC,
 					 "enable str9xpec turbo mode");
 	register_command(cmd_ctx, str9xpec_cmd, "disable_turbo", str9xpec_handle_flash_disable_turbo_command, COMMAND_EXEC,
@@ -107,24 +107,22 @@ int str9xpec_register_commands(struct command_context_s *cmd_ctx)
 					 "unlock str9xpec device");
 	register_command(cmd_ctx, str9xpec_cmd, "part_id", str9xpec_handle_part_id_command, COMMAND_EXEC,
 					 "print part id of str9xpec flash bank <num>");
-	
+
 	return ERROR_OK;
 }
 
 int str9xpec_set_instr(int chain_pos, u32 new_instr, enum tap_state end_state)
 {
 	jtag_device_t *device = jtag_get_device(chain_pos);
-	
 	if (device == NULL)
 	{
-		LOG_DEBUG("Invalid Target");
 		return ERROR_TARGET_INVALID;
 	}
-		
+
 	if (buf_get_u32(device->cur_instr, 0, device->ir_length) != new_instr)
 	{
 		scan_field_t field;
-				
+
 		field.device = chain_pos;
 		field.num_bits = device->ir_length;
 		field.out_value = calloc(CEIL(field.num_bits, 8), 1);
@@ -135,12 +133,12 @@ int str9xpec_set_instr(int chain_pos, u32 new_instr, enum tap_state end_state)
 		field.in_check_mask = NULL;
 		field.in_handler = NULL;
 		field.in_handler_priv = NULL;
-		
+
 		jtag_add_ir_scan(1, &field, end_state);
-		
+
 		free(field.out_value);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -148,10 +146,10 @@ u8 str9xpec_isc_status(int chain_pos)
 {
 	scan_field_t field;
 	u8 status;
-	
+
 	if (str9xpec_set_instr(chain_pos, ISC_NOOP, TAP_PI) != ERROR_OK)
 		return ISC_STATUS_ERROR;
-	
+
 	field.device = chain_pos;
 	field.num_bits = 8;
 	field.out_value = NULL;
@@ -161,15 +159,15 @@ u8 str9xpec_isc_status(int chain_pos)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_RTI);
 	jtag_execute_queue();
-	
+
 	LOG_DEBUG("status: 0x%2.2x", status);
-	
+
 	if (status & ISC_STATUS_SECURITY)
 		LOG_INFO("Device Security Bit Set");
-	
+
 	return status;
 }
 
@@ -178,16 +176,16 @@ int str9xpec_isc_enable(struct flash_bank_s *bank)
 	u8 status;
 	u32 chain_pos;
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	if (str9xpec_info->isc_enable)
 		return ERROR_OK;
-	
+
 	/* enter isc mode */
 	if (str9xpec_set_instr(chain_pos, ISC_ENABLE, TAP_RTI) != ERROR_OK)
 		return ERROR_TARGET_INVALID;
-	
+
 	/* check ISC status */
 	status = str9xpec_isc_status(chain_pos);
 	if (status & ISC_STATUS_MODE)
@@ -196,7 +194,7 @@ int str9xpec_isc_enable(struct flash_bank_s *bank)
 		str9xpec_info->isc_enable = 1;
 		LOG_DEBUG("ISC_MODE Enabled");
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -205,18 +203,18 @@ int str9xpec_isc_disable(struct flash_bank_s *bank)
 	u8 status;
 	u32 chain_pos;
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	if (!str9xpec_info->isc_enable)
 		return ERROR_OK;
-	
+
 	if (str9xpec_set_instr(chain_pos, ISC_DISABLE, TAP_RTI) != ERROR_OK)
 		return ERROR_TARGET_INVALID;
-	
+
 	/* delay to handle aborts */
 	jtag_add_sleep(50);
-	
+
 	/* check ISC status */
 	status = str9xpec_isc_status(chain_pos);
 	if (!(status & ISC_STATUS_MODE))
@@ -225,7 +223,7 @@ int str9xpec_isc_disable(struct flash_bank_s *bank)
 		str9xpec_info->isc_enable = 0;
 		LOG_DEBUG("ISC_MODE Disabled");
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -234,16 +232,16 @@ int str9xpec_read_config(struct flash_bank_s *bank)
 	scan_field_t field;
 	u8 status;
 	u32 chain_pos;
-		
+
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	LOG_DEBUG("ISC_CONFIGURATION");
-	
+
 	/* execute ISC_CONFIGURATION command */
 	str9xpec_set_instr(chain_pos, ISC_CONFIGURATION, TAP_PI);
-	
+
 	field.device = chain_pos;
 	field.num_bits = 64;
 	field.out_value = NULL;
@@ -253,25 +251,25 @@ int str9xpec_read_config(struct flash_bank_s *bank)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_RTI);
 	jtag_execute_queue();
-	
+
 	status = str9xpec_isc_status(chain_pos);
-	
+
 	return status;
 }
 
 int str9xpec_build_block_list(struct flash_bank_s *bank)
 {
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	int i;
 	int num_sectors;
 	int b0_sectors = 0, b1_sectors = 0;
 	u32 offset = 0;
 	int b1_size = 0x2000;
-	
+
 	switch (bank->size)
 	{
 		case (256 * 1024):
@@ -297,15 +295,15 @@ int str9xpec_build_block_list(struct flash_bank_s *bank)
 			LOG_ERROR("BUG: unknown bank->size encountered");
 			exit(-1);
 	}
-	
+
 	num_sectors = b0_sectors + b1_sectors;
-	
+
 	bank->num_sectors = num_sectors;
 	bank->sectors = malloc(sizeof(flash_sector_t) * num_sectors);
 	str9xpec_info->sector_bits = malloc(sizeof(u32) * num_sectors);
-	
+
 	num_sectors = 0;
-	
+
 	for (i = 0; i < b0_sectors; i++)
 	{
 		bank->sectors[num_sectors].offset = offset;
@@ -325,7 +323,7 @@ int str9xpec_build_block_list(struct flash_bank_s *bank)
 		bank->sectors[num_sectors].is_protected = 1;
 		str9xpec_info->sector_bits[num_sectors++] = i + 32;
 	}
-		
+
 	return ERROR_OK;
 }
 
@@ -337,32 +335,32 @@ int str9xpec_flash_bank_command(struct command_context_s *cmd_ctx, char *cmd, ch
 	armv4_5_common_t *armv4_5 = NULL;
 	arm7_9_common_t *arm7_9 = NULL;
 	arm_jtag_t *jtag_info = NULL;
-	
+
 	if (argc < 6)
 	{
 		LOG_WARNING("incomplete flash_bank str9x configuration");
 		return ERROR_FLASH_BANK_INVALID;
 	}
-	
+
 	str9xpec_info = malloc(sizeof(str9xpec_flash_controller_t));
 	bank->driver_priv = str9xpec_info;
-	
+
 	/* find out jtag position of flash controller
 	 * it is always after the arm966 core */
-	
+
 	armv4_5 = bank->target->arch_info;
 	arm7_9 = armv4_5->arch_info;
 	jtag_info = &arm7_9->jtag_info;
-	
+
 	str9xpec_info->chain_pos = (jtag_info->chain_pos - 1);
 	str9xpec_info->isc_enable = 0;
 	str9xpec_info->devarm = NULL;
-	
+
 	str9xpec_build_block_list(bank);
-	
+
 	/* clear option byte register */
 	buf_set_u32(str9xpec_info->options, 0, 64, 0);
-	
+
 	return ERROR_OK;
 }
 
@@ -373,30 +371,30 @@ int str9xpec_blank_check(struct flash_bank_s *bank, int first, int last)
 	u32 chain_pos;
 	int i;
 	u8 *buffer = NULL;
-		
+
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	if (!str9xpec_info->isc_enable) {
 		str9xpec_isc_enable( bank );
 	}
-	
+
 	if (!str9xpec_info->isc_enable) {
 		return ERROR_FLASH_OPERATION_FAILED;
 	}
-	
+
 	buffer = calloc(CEIL(64, 8), 1);
 
 	LOG_DEBUG("blank check: first_bank: %i, last_bank: %i", first, last);
-	
+
 	for (i = first; i <= last; i++) {
 		buf_set_u32(buffer, str9xpec_info->sector_bits[i], 1, 1);
 	}
-	
+
 	/* execute ISC_BLANK_CHECK command */
 	str9xpec_set_instr(chain_pos, ISC_BLANK_CHECK, TAP_PI);
-	
+
 	field.device = chain_pos;
 	field.num_bits = 64;
 	field.out_value = buffer;
@@ -406,10 +404,10 @@ int str9xpec_blank_check(struct flash_bank_s *bank, int first, int last)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_RTI);
 	jtag_add_sleep(40000);
-	
+
 	/* read blank check result */
 	field.device = chain_pos;
 	field.num_bits = 64;
@@ -420,12 +418,12 @@ int str9xpec_blank_check(struct flash_bank_s *bank, int first, int last)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_PI);
 	jtag_execute_queue();
-	
+
 	status = str9xpec_isc_status(chain_pos);
-	
+
 	for (i = first; i <= last; i++)
 	{
 		if (buf_get_u32(buffer, str9xpec_info->sector_bits[i], 1))
@@ -433,13 +431,13 @@ int str9xpec_blank_check(struct flash_bank_s *bank, int first, int last)
 		else
 			bank->sectors[i].is_erased = 1;
 	}
-	
+
 	free(buffer);
-	
+
 	str9xpec_isc_disable(bank);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
-		return ERROR_FLASH_OPERATION_FAILED; 
+		return ERROR_FLASH_OPERATION_FAILED;
 	return ERROR_OK;
 }
 
@@ -447,11 +445,11 @@ int str9xpec_protect_check(struct flash_bank_s *bank)
 {
 	u8 status;
 	int i;
-		
+
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	status = str9xpec_read_config(bank);
-	
+
 	for (i = 0; i < bank->num_sectors; i++)
 	{
 		if (buf_get_u32(str9xpec_info->options, str9xpec_info->sector_bits[i], 1))
@@ -459,7 +457,7 @@ int str9xpec_protect_check(struct flash_bank_s *bank)
 		else
 			bank->sectors[i].is_protected = 0;
 	}
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
 	return ERROR_OK;
@@ -472,47 +470,47 @@ int str9xpec_erase_area(struct flash_bank_s *bank, int first, int last)
 	u32 chain_pos;
 	int i;
 	u8 *buffer = NULL;
-	
+
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	if (!str9xpec_info->isc_enable) {
 		str9xpec_isc_enable( bank );
 	}
-	
+
 	if (!str9xpec_info->isc_enable) {
 		return ISC_STATUS_ERROR;
 	}
-	
+
 	buffer = calloc(CEIL(64, 8), 1);
-	
+
 	LOG_DEBUG("erase: first_bank: %i, last_bank: %i", first, last);
-	
+
 	/* last bank: 0xFF signals a full erase (unlock complete device) */
 	/* last bank: 0xFE signals a option byte erase */
 	if (last == 0xFF)
 	{
 		for (i = 0; i < 64; i++) {
 			buf_set_u32(buffer, i, 1, 1);
-		}	
+		}
 	}
 	else if (last == 0xFE)
 	{
 		buf_set_u32(buffer, 49, 1, 1);
 	}
 	else
-	{	
+	{
 		for (i = first; i <= last; i++) {
 			buf_set_u32(buffer, str9xpec_info->sector_bits[i], 1, 1);
 		}
 	}
-	
+
 	LOG_DEBUG("ISC_ERASE");
-	
+
 	/* execute ISC_ERASE command */
 	str9xpec_set_instr(chain_pos, ISC_ERASE, TAP_PI);
-	
+
 	field.device = chain_pos;
 	field.num_bits = 64;
 	field.out_value = buffer;
@@ -522,33 +520,33 @@ int str9xpec_erase_area(struct flash_bank_s *bank, int first, int last)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_RTI);
 	jtag_execute_queue();
-	
+
 	jtag_add_sleep(10);
-	
+
 	/* wait for erase completion */
 	while (!((status = str9xpec_isc_status(chain_pos)) & ISC_STATUS_BUSY)) {
 		alive_sleep(1);
 	}
-	
+
 	free(buffer);
-	
+
 	str9xpec_isc_disable(bank);
-	
+
 	return status;
 }
 
 int str9xpec_erase(struct flash_bank_s *bank, int first, int last)
 {
 	int status;
-	
+
 	status = str9xpec_erase_area(bank, first, last);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
-	
+
 	return ERROR_OK;
 }
 
@@ -558,26 +556,26 @@ int str9xpec_lock_device(struct flash_bank_s *bank)
 	u8 status;
 	u32 chain_pos;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	str9xpec_info = bank->driver_priv;
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	if (!str9xpec_info->isc_enable) {
 		str9xpec_isc_enable( bank );
 	}
-	
+
 	if (!str9xpec_info->isc_enable) {
 		return ISC_STATUS_ERROR;
 	}
-	
+
 	/* set security address */
 	str9xpec_set_address(bank, 0x80);
-	
+
 	/* execute ISC_PROGRAM command */
 	str9xpec_set_instr(chain_pos, ISC_PROGRAM_SECURITY, TAP_RTI);
-	
+
 	str9xpec_set_instr(chain_pos, ISC_NOOP, TAP_PI);
-	
+
 	do {
 		field.device = chain_pos;
 		field.num_bits = 8;
@@ -588,23 +586,23 @@ int str9xpec_lock_device(struct flash_bank_s *bank)
 		field.in_check_mask = NULL;
 		field.in_handler = NULL;
 		field.in_handler_priv = NULL;
-		
+
 		jtag_add_dr_scan(1, &field, -1);
 		jtag_execute_queue();
-		
+
 	} while(!(status & ISC_STATUS_BUSY));
-	
+
 	str9xpec_isc_disable(bank);
-	
+
 	return status;
 }
 
 int str9xpec_unlock_device(struct flash_bank_s *bank)
 {
 	u8 status;
-	
+
 	status = str9xpec_erase_area(bank, 0, 255);
-	
+
 	return status;
 }
 
@@ -612,16 +610,16 @@ int str9xpec_protect(struct flash_bank_s *bank, int set, int first, int last)
 {
 	u8 status;
 	int i;
-	
+
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	status = str9xpec_read_config(bank);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
 
 	LOG_DEBUG("protect: first_bank: %i, last_bank: %i", first, last);
-	
+
 	/* last bank: 0xFF signals a full device protect */
 	if (last == 0xFF)
 	{
@@ -636,7 +634,7 @@ int str9xpec_protect(struct flash_bank_s *bank, int set, int first, int last)
 		}
 	}
 	else
-	{	
+	{
 		for (i = first; i <= last; i++)
 		{
 			if( set )
@@ -644,13 +642,13 @@ int str9xpec_protect(struct flash_bank_s *bank, int set, int first, int last)
 			else
 				buf_set_u32(str9xpec_info->options, str9xpec_info->sector_bits[i], 1, 0);
 		}
-		
+
 		status = str9xpec_write_options(bank);
 	}
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
-	
+
 	return ERROR_OK;
 }
 
@@ -659,12 +657,12 @@ int str9xpec_set_address(struct flash_bank_s *bank, u8 sector)
 	u32 chain_pos;
 	scan_field_t field;
 	str9xpec_flash_controller_t *str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	/* set flash controller address */
 	str9xpec_set_instr(chain_pos, ISC_ADDRESS_SHIFT, TAP_PI);
-	
+
 	field.device = chain_pos;
 	field.num_bits = 8;
 	field.out_value = &sector;
@@ -674,9 +672,9 @@ int str9xpec_set_address(struct flash_bank_s *bank, u8 sector)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, -1);
-		
+
 	return ERROR_OK;
 }
 
@@ -694,28 +692,28 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 	int i;
 	u32 first_sector = 0;
 	u32 last_sector = 0;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	if (!str9xpec_info->isc_enable) {
 		str9xpec_isc_enable(bank);
 	}
-	
+
 	if (!str9xpec_info->isc_enable) {
 		return ERROR_FLASH_OPERATION_FAILED;
 	}
-	
+
 	if (offset & 0x7)
 	{
 		LOG_WARNING("offset 0x%x breaks required 8-byte alignment", offset);
 		return ERROR_FLASH_DST_BREAKS_ALIGNMENT;
 	}
-	
+
 	for (i = 0; i < bank->num_sectors; i++)
 	{
 		u32 sec_start = bank->sectors[i].offset;
 		u32 sec_end = sec_start + bank->sectors[i].size;
-		
+
 		/* check if destination falls within the current sector */
 		if ((check_address >= sec_start) && (check_address < sec_end))
 		{
@@ -725,35 +723,35 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 			else
 				check_address = sec_end;
 		}
-		
+
 		if ((offset >= sec_start) && (offset < sec_end)){
 			first_sector = i;
 		}
-		
+
 		if ((offset + count >= sec_start) && (offset + count < sec_end)){
 			last_sector = i;
 		}
 	}
-	
+
 	if (check_address != offset + count)
 		return ERROR_FLASH_DST_OUT_OF_BANK;
 
 	LOG_DEBUG("first_sector: %i, last_sector: %i", first_sector, last_sector);
-	
+
 	scanbuf = calloc(CEIL(64, 8), 1);
-	
+
 	LOG_DEBUG("ISC_PROGRAM");
-	
+
 	for (i = first_sector; i <= last_sector; i++)
 	{
 		str9xpec_set_address(bank, str9xpec_info->sector_bits[i]);
-		
+
 		dwords_remaining = dwords_remaining < (bank->sectors[i].size/8) ? dwords_remaining : (bank->sectors[i].size/8);
 
 		while (dwords_remaining > 0)
-		{	
+		{
 			str9xpec_set_instr(chain_pos, ISC_PROGRAM, TAP_PI);
-			
+
 			field.device = chain_pos;
 			field.num_bits = 64;
 			field.out_value = (buffer + bytes_written);
@@ -763,14 +761,14 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 			field.in_check_mask = NULL;
 			field.in_handler = NULL;
 			field.in_handler_priv = NULL;
-			
+
 			jtag_add_dr_scan(1, &field, TAP_RTI);
-			
+
 			/* small delay before polling */
 			jtag_add_sleep(50);
-			
+
 			str9xpec_set_instr(chain_pos, ISC_NOOP, TAP_PI);
-			
+
 			do {
 				field.device = chain_pos;
 				field.num_bits = 8;
@@ -781,39 +779,39 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 				field.in_check_mask = NULL;
 				field.in_handler = NULL;
 				field.in_handler_priv = NULL;
-				
+
 				jtag_add_dr_scan(1, &field, -1);
 				jtag_execute_queue();
-				
+
 				status = buf_get_u32(scanbuf, 0, 8);
-				
+
 			} while(!(status & ISC_STATUS_BUSY));
-			
+
 			if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 				return ERROR_FLASH_OPERATION_FAILED;
-			
+
 			/* if ((status & ISC_STATUS_INT_ERROR) != STR9XPEC_ISC_INTFAIL)
 				return ERROR_FLASH_OPERATION_FAILED; */
-		
+
 			dwords_remaining--;
 			bytes_written += 8;
 		}
 	}
-	
+
 	if (bytes_remaining)
 	{
 		u8 last_dword[8] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 		int i = 0;
-				
+
 		while(bytes_remaining > 0)
 		{
-			last_dword[i++] = *(buffer + bytes_written); 
+			last_dword[i++] = *(buffer + bytes_written);
 			bytes_remaining--;
 			bytes_written++;
 		}
-		
+
 		str9xpec_set_instr(chain_pos, ISC_PROGRAM, TAP_PI);
-		
+
 		field.device = chain_pos;
 		field.num_bits = 64;
 		field.out_value = last_dword;
@@ -823,14 +821,14 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 		field.in_check_mask = NULL;
 		field.in_handler = NULL;
 		field.in_handler_priv = NULL;
-		
+
 		jtag_add_dr_scan(1, &field, TAP_RTI);
-		
+
 		/* small delay before polling */
 		jtag_add_sleep(50);
-		
+
 		str9xpec_set_instr(chain_pos, ISC_NOOP, TAP_PI);
-		
+
 		do {
 			field.device = chain_pos;
 			field.num_bits = 8;
@@ -841,17 +839,17 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 			field.in_check_mask = NULL;
 			field.in_handler = NULL;
 			field.in_handler_priv = NULL;
-			
+
 			jtag_add_dr_scan(1, &field, -1);
 			jtag_execute_queue();
-			
+
 			status = buf_get_u32(scanbuf, 0, 8);
-			
+
 		} while(!(status & ISC_STATUS_BUSY));
-		
+
 		if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 			return ERROR_FLASH_OPERATION_FAILED;
-		
+
 		/* if ((status & ISC_STATUS_INT_ERROR) != STR9XPEC_ISC_INTFAIL)
 			return ERROR_FLASH_OPERATION_FAILED; */
 	}
@@ -859,7 +857,7 @@ int str9xpec_write(struct flash_bank_s *bank, u8 *buffer, u32 offset, u32 count)
 	free(scanbuf);
 
 	str9xpec_isc_disable(bank);
-				
+
 	return ERROR_OK;
 }
 
@@ -881,21 +879,21 @@ int str9xpec_handle_part_id_command(struct command_context_s *cmd_ctx, char *cmd
 	{
 		return ERROR_COMMAND_SYNTAX_ERROR;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	buffer = calloc(CEIL(32, 8), 1);
-	
+
 	str9xpec_set_instr(chain_pos, ISC_IDCODE, TAP_PI);
-	
+
 	field.device = chain_pos;
 	field.num_bits = 32;
 	field.out_value = NULL;
@@ -905,16 +903,16 @@ int str9xpec_handle_part_id_command(struct command_context_s *cmd_ctx, char *cmd
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_RTI);
 	jtag_execute_queue();
-	
+
 	idcode = buf_get_u32(buffer, 0, 32);
-	
+
 	command_print(cmd_ctx, "str9xpec part id: 0x%8.8x", idcode);
-	
+
 	free(buffer);
-	
+
 	return ERROR_OK;
 }
 
@@ -934,57 +932,57 @@ int str9xpec_handle_flash_options_read_command(struct command_context_s *cmd_ctx
 	flash_bank_t *bank;
 	u8 status;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "str9xpec options_read <bank>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	status = str9xpec_read_config(bank);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
-	
+
 	/* boot bank */
 	if (buf_get_u32(str9xpec_info->options, STR9XPEC_OPT_CSMAPBIT, 1))
 		command_print(cmd_ctx, "CS Map: bank1");
 	else
 		command_print(cmd_ctx, "CS Map: bank0");
-	
+
 	/* OTP lock */
 	if (buf_get_u32(str9xpec_info->options, STR9XPEC_OPT_OTPBIT, 1))
 		command_print(cmd_ctx, "OTP Lock: OTP Locked");
 	else
 		command_print(cmd_ctx, "OTP Lock: OTP Unlocked");
-	
+
 	/* LVD Threshold */
 	if (buf_get_u32(str9xpec_info->options, STR9XPEC_OPT_LVDTHRESBIT, 1))
 		command_print(cmd_ctx, "LVD Threshold: 2.7v");
 	else
 		command_print(cmd_ctx, "LVD Threshold: 2.4v");
-	
+
 	/* LVD reset warning */
 	if (buf_get_u32(str9xpec_info->options, STR9XPEC_OPT_LVDWARNBIT, 1))
 		command_print(cmd_ctx, "LVD Reset Warning: VDD or VDDQ Inputs");
 	else
 		command_print(cmd_ctx, "LVD Reset Warning: VDD Input Only");
-	
+
 	/* LVD reset select */
 	if (buf_get_u32(str9xpec_info->options, STR9XPEC_OPT_LVDSELBIT, 1))
 		command_print(cmd_ctx, "LVD Reset Selection: VDD or VDDQ Inputs");
 	else
 		command_print(cmd_ctx, "LVD Reset Selection: VDD Input Only");
-	
+
 	return ERROR_OK;
 }
 
@@ -994,33 +992,33 @@ int str9xpec_write_options(struct flash_bank_s *bank)
 	u8 status;
 	u32 chain_pos;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	str9xpec_info = bank->driver_priv;
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	/* erase config options first */
 	status = str9xpec_erase_area( bank, 0xFE, 0xFE );
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
-		return status; 
-	
+		return status;
+
 	if (!str9xpec_info->isc_enable) {
 		str9xpec_isc_enable( bank );
 	}
-	
+
 	if (!str9xpec_info->isc_enable) {
 		return ISC_STATUS_ERROR;
 	}
-	
+
 	/* according to data 64th bit has to be set */
 	buf_set_u32(str9xpec_info->options, 63, 1, 1);
-	
+
 	/* set option byte address */
 	str9xpec_set_address(bank, 0x50);
-	
+
 	/* execute ISC_PROGRAM command */
 	str9xpec_set_instr(chain_pos, ISC_PROGRAM, TAP_PI);
-		
+
 	field.device = chain_pos;
 	field.num_bits = 64;
 	field.out_value = str9xpec_info->options;
@@ -1030,14 +1028,14 @@ int str9xpec_write_options(struct flash_bank_s *bank)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	jtag_add_dr_scan(1, &field, TAP_RTI);
-	
+
 	/* small delay before polling */
 	jtag_add_sleep(50);
-	
+
 	str9xpec_set_instr(chain_pos, ISC_NOOP, TAP_PI);
-	
+
 	do {
 		field.device = chain_pos;
 		field.num_bits = 8;
@@ -1048,14 +1046,14 @@ int str9xpec_write_options(struct flash_bank_s *bank)
 		field.in_check_mask = NULL;
 		field.in_handler = NULL;
 		field.in_handler_priv = NULL;
-		
+
 		jtag_add_dr_scan(1, &field, -1);
 		jtag_execute_queue();
-		
+
 	} while(!(status & ISC_STATUS_BUSY));
-	
+
 	str9xpec_isc_disable(bank);
-	
+
 	return status;
 }
 
@@ -1063,25 +1061,25 @@ int str9xpec_handle_flash_options_write_command(struct command_context_s *cmd_ct
 {
 	flash_bank_t *bank;
 	u8 status;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "str9xpec options_write <bank>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	status = str9xpec_write_options(bank);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
-	
+
 	return ERROR_OK;
 }
 
@@ -1089,22 +1087,22 @@ int str9xpec_handle_flash_options_cmap_command(struct command_context_s *cmd_ctx
 {
 	flash_bank_t *bank;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 2)
 	{
 		command_print(cmd_ctx, "str9xpec options_cmap <bank> <bank0|bank1>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	if (strcmp(args[1], "bank1") == 0)
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_CSMAPBIT, 1, 1);
@@ -1113,7 +1111,7 @@ int str9xpec_handle_flash_options_cmap_command(struct command_context_s *cmd_ctx
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_CSMAPBIT, 1, 0);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -1121,22 +1119,22 @@ int str9xpec_handle_flash_options_lvdthd_command(struct command_context_s *cmd_c
 {
 	flash_bank_t *bank;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 2)
 	{
 		command_print(cmd_ctx, "str9xpec options_lvdthd <bank> <2.4v|2.7v>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	if (strcmp(args[1], "2.7v") == 0)
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_LVDTHRESBIT, 1, 1);
@@ -1145,7 +1143,7 @@ int str9xpec_handle_flash_options_lvdthd_command(struct command_context_s *cmd_c
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_LVDTHRESBIT, 1, 0);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -1153,22 +1151,22 @@ int str9xpec_handle_flash_options_lvdsel_command(struct command_context_s *cmd_c
 {
 	flash_bank_t *bank;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 2)
 	{
 		command_print(cmd_ctx, "str9xpec options_lvdsel <bank> <vdd|vdd_vddq>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	if (strcmp(args[1], "vdd_vddq") == 0)
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_LVDSELBIT, 1, 1);
@@ -1177,7 +1175,7 @@ int str9xpec_handle_flash_options_lvdsel_command(struct command_context_s *cmd_c
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_LVDSELBIT, 1, 0);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -1185,22 +1183,22 @@ int str9xpec_handle_flash_options_lvdwarn_command(struct command_context_s *cmd_
 {
 	flash_bank_t *bank;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 2)
 	{
 		command_print(cmd_ctx, "str9xpec options_lvdwarn <bank> <vdd|vdd_vddq>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	if (strcmp(args[1], "vdd_vddq") == 0)
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_LVDWARNBIT, 1, 1);
@@ -1209,7 +1207,7 @@ int str9xpec_handle_flash_options_lvdwarn_command(struct command_context_s *cmd_
 	{
 		buf_set_u32(str9xpec_info->options, STR9XPEC_OPT_LVDWARNBIT, 1, 0);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -1217,25 +1215,25 @@ int str9xpec_handle_flash_lock_command(struct command_context_s *cmd_ctx, char *
 {
 	u8 status;
 	flash_bank_t *bank;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "str9xpec lock <bank>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	status = str9xpec_lock_device(bank);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
-	
+
 	return ERROR_OK;
 }
 
@@ -1243,65 +1241,71 @@ int str9xpec_handle_flash_unlock_command(struct command_context_s *cmd_ctx, char
 {
 	u8 status;
 	flash_bank_t *bank;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "str9xpec unlock <bank>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	status = str9xpec_unlock_device(bank);
-	
+
 	if ((status & ISC_STATUS_ERROR) != STR9XPEC_ISC_SUCCESS)
 		return ERROR_FLASH_OPERATION_FAILED;
-	
+
 	return ERROR_OK;
 }
 
 int str9xpec_handle_flash_enable_turbo_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
+	int retval;
 	flash_bank_t *bank;
 	u32 chain_pos;
 	jtag_device_t* dev0;
 	jtag_device_t* dev2;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "str9xpec enable_turbo <bank>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	/* remove arm core from chain - enter turbo mode */
-	
+
 	str9xpec_set_instr(chain_pos+2, 0xD, TAP_RTI);
-	jtag_execute_queue();
-	
+	if ((retval=jtag_execute_queue())!=ERROR_OK)
+		return retval;
+
 	/* modify scan chain - str9 core has been removed */
 	dev0 = jtag_get_device(chain_pos);
+	if (dev0 == NULL)
+		return ERROR_FAIL;
 	str9xpec_info->devarm = jtag_get_device(chain_pos+1);
 	dev2 = jtag_get_device(chain_pos+2);
+	if (dev2 == NULL)
+		return ERROR_FAIL;
 	dev0->next = dev2;
 	jtag_num_devices--;
-	
+
 	return ERROR_OK;
 }
 
@@ -1311,36 +1315,39 @@ int str9xpec_handle_flash_disable_turbo_command(struct command_context_s *cmd_ct
 	u32 chain_pos;
 	jtag_device_t* dev0;
 	str9xpec_flash_controller_t *str9xpec_info = NULL;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "str9xpec disable_turbo <bank>");
-		return ERROR_OK;	
+		return ERROR_OK;
 	}
-	
+
 	bank = get_flash_bank_by_num(strtoul(args[0], NULL, 0));
 	if (!bank)
 	{
 		command_print(cmd_ctx, "flash bank '#%s' is out of bounds", args[0]);
 		return ERROR_OK;
 	}
-	
+
 	str9xpec_info = bank->driver_priv;
-	
+
 	chain_pos = str9xpec_info->chain_pos;
-	
+
 	dev0 = jtag_get_device(chain_pos);
-	
+	if (dev0 == NULL)
+		return ERROR_FAIL;
+
+
 	/* exit turbo mode via TLR */
 	str9xpec_set_instr(chain_pos, ISC_NOOP, TAP_TLR);
 	jtag_execute_queue();
-	
+
 	/* restore previous scan chain */
 	if( str9xpec_info->devarm ) {
 		dev0->next = str9xpec_info->devarm;
 		jtag_num_devices++;
 		str9xpec_info->devarm = NULL;
 	}
-	
+
 	return ERROR_OK;
 }
diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index 6a84db4..d8f3ccd 100644
--- a/src/jtag/jtag.c
+++ b/src/jtag/jtag.c
@@ -369,7 +369,7 @@ jtag_device_t* jtag_get_device(int num)
 	}
 
 	LOG_ERROR("jtag device number %d not defined", num);
-	exit(-1);
+	return NULL;
 }
 
 void* cmd_queue_alloc(size_t size)
@@ -477,6 +477,10 @@ int MINIDRIVER(interface_jtag_add_ir_scan)(int num_fields, scan_field_t *fields,
 	{
 		int found = 0;
 		device = jtag_get_device(i);
+		if (device == NULL)
+		{
+			exit(-1);
+		}
 		scan_size = device->ir_length;
 		(*last_cmd)->cmd.scan->fields[i].device = i;
 		(*last_cmd)->cmd.scan->fields[i].num_bits = scan_size;
@@ -2120,7 +2124,12 @@ int handle_irscan_command(struct command_context_s *cmd_ctx, char *cmd, char **a
 	for (i = 0; i < argc / 2; i++)
 	{
 		int device = strtoul(args[i*2], NULL, 0);
-		int field_size = jtag_get_device(device)->ir_length;
+		jtag_device_t *device_ptr=jtag_get_device(device);
+		if (device==NULL)
+		{
+			return ERROR_FAIL;
+		}
+		int field_size = device_ptr->ir_length;
 		fields[i].device = device;
 		fields[i].out_value = malloc(CEIL(field_size, 8));
 		buf_set_u32(fields[i].out_value, 0, field_size, strtoul(args[i*2+1], NULL, 0));
diff --git a/src/jtag/zy1000.c b/src/jtag/zy1000.c
index a50ed52..5ec1d8a 100644
--- a/src/jtag/zy1000.c
+++ b/src/jtag/zy1000.c
@@ -501,6 +501,11 @@ int interface_jtag_add_ir_scan(int num_fields, scan_field_t *fields, enum tap_st
 		int pause=i==(jtag_num_devices-1);
 		int found = 0;
 		device = jtag_get_device(i);
+		if (device==NULL)
+		{
+			return ERROR_FAIL;
+		}
+
 		scan_size = device->ir_length;
 
 		/* search the list */
@@ -521,7 +526,7 @@ int interface_jtag_add_ir_scan(int num_fields, scan_field_t *fields, enum tap_st
 
 				scanFields(1, fields+j, TAP_SI, pause);
 				/* update device information */
-				buf_cpy(fields[j].out_value, jtag_get_device(i)->cur_instr, scan_size);
+				buf_cpy(fields[j].out_value, device->cur_instr, scan_size);
 
 				device->bypass = 0;
 				break;
@@ -539,7 +544,7 @@ int interface_jtag_add_ir_scan(int num_fields, scan_field_t *fields, enum tap_st
 			tmp.num_bits = scan_size;
 			scanFields(1, &tmp, TAP_SI, pause);
 			/* update device information */
-			buf_cpy(tmp.out_value, jtag_get_device(i)->cur_instr, scan_size);
+			buf_cpy(tmp.out_value, device->cur_instr, scan_size);
 			device->bypass = 1;
 		}
 	}
diff --git a/src/pld/virtex2.c b/src/pld/virtex2.c
index e0ec27d..9ddd1f6 100644
--- a/src/pld/virtex2.c
+++ b/src/pld/virtex2.c
@@ -46,11 +46,13 @@ pld_driver_t virtex2_pld =
 int virtex2_set_instr(int chain_pos, u32 new_instr)
 {
 	jtag_device_t *device = jtag_get_device(chain_pos);
-	
+	if (device==NULL)
+		return ERROR_FAIL;
+
 	if (buf_get_u32(device->cur_instr, 0, device->ir_length) != new_instr)
 	{
 		scan_field_t field;
-	
+
 		field.device = chain_pos;
 		field.num_bits = device->ir_length;
 		field.out_value = calloc(CEIL(field.num_bits, 8), 1);
@@ -61,12 +63,12 @@ int virtex2_set_instr(int chain_pos, u32 new_instr)
 		field.in_check_mask = NULL;
 		field.in_handler = NULL;
 		field.in_handler_priv = NULL;
-		
+
 		jtag_add_ir_scan(1, &field, TAP_RTI);
-		
+
 		free(field.out_value);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -76,7 +78,7 @@ int virtex2_send_32(struct pld_device_s *pld_device, int num_words, u32 *words)
 	scan_field_t scan_field;
 	u8 *values;
 	int i;
-	
+
 	values = malloc(num_words * 4);
 
 	scan_field.device = virtex2_info->chain_pos;
@@ -88,16 +90,16 @@ int virtex2_send_32(struct pld_device_s *pld_device, int num_words, u32 *words)
 	scan_field.in_check_mask = NULL;
 	scan_field.in_handler = NULL;
 	scan_field.in_handler_priv = NULL;
-	
+
 	for (i = 0; i < num_words; i++)
 		buf_set_u32(values + 4 * i, 0, 32, flip_u32(*words++, 32));
-	
+
 	virtex2_set_instr(virtex2_info->chain_pos, 0x5); /* CFG_IN */
-	
+
 	jtag_add_dr_scan(1, &scan_field, TAP_PD);
-	
+
 	free(values);
-	
+
 	return ERROR_OK;
 }
 
@@ -112,7 +114,7 @@ int virtex2_receive_32(struct pld_device_s *pld_device, int num_words, u32 *word
 {
 	virtex2_pld_device_t *virtex2_info = pld_device->driver_priv;
 	scan_field_t scan_field;
-	
+
 	scan_field.device = virtex2_info->chain_pos;
 	scan_field.num_bits = 32;
 	scan_field.out_value = NULL;
@@ -121,37 +123,37 @@ int virtex2_receive_32(struct pld_device_s *pld_device, int num_words, u32 *word
 	scan_field.in_check_value = NULL;
 	scan_field.in_check_mask = NULL;
 	scan_field.in_handler = virtex2_jtag_buf_to_u32;
-	
+
 	virtex2_set_instr(virtex2_info->chain_pos, 0x4); /* CFG_OUT */
-	
+
 	while (num_words--)
 	{
 		scan_field.in_handler_priv = words++;
 		jtag_add_dr_scan(1, &scan_field, TAP_PD);
 	}
-	
+
 	return ERROR_OK;
 }
 
 int virtex2_read_stat(struct pld_device_s *pld_device, u32 *status)
 {
 	u32 data[5];
-	
+
 	jtag_add_tlr();
-	
+
 	data[0] = 0xaa995566; /* synch word */
 	data[1] = 0x2800E001; /* Type 1, read, address 7, 1 word */
 	data[2] = 0x20000000; /* NOOP (Type 1, read, address 0, 0 words */
 	data[3] = 0x20000000; /* NOOP */
 	data[4] = 0x20000000; /* NOOP */
 	virtex2_send_32(pld_device, 5, data);
-	
+
 	virtex2_receive_32(pld_device, 1, status);
-	
+
 	jtag_execute_queue();
-	
+
 	LOG_DEBUG("status: 0x%8.8x", *status);
-	
+
 	return ERROR_OK;
 }
 
@@ -171,29 +173,29 @@ int virtex2_load(struct pld_device_s *pld_device, char *filename)
 	field.in_check_mask = NULL;
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
-	
+
 	if ((retval = xilinx_read_bit_file(&bit_file, filename)) != ERROR_OK)
 		return retval;
-	
+
 	jtag_add_end_state(TAP_RTI);
 	virtex2_set_instr(virtex2_info->chain_pos, 0xb); /* JPROG_B */
 	jtag_execute_queue();
 	jtag_add_sleep(1000);
-	
+
 	virtex2_set_instr(virtex2_info->chain_pos, 0x5); /* CFG_IN */
 	jtag_execute_queue();
-	
+
 	for (i = 0; i < bit_file.length; i++)
 		bit_file.data[i] = flip_u32(bit_file.data[i], 8);
-	
+
 	field.num_bits = bit_file.length * 8;
 	field.out_value = bit_file.data;
 
 	jtag_add_dr_scan(1, &field, TAP_PD);
 	jtag_execute_queue();
-	
+
 	jtag_add_tlr();
-	
+
 	jtag_add_end_state(TAP_RTI);
 	virtex2_set_instr(virtex2_info->chain_pos, 0xc); /* JSTART */
 	jtag_add_runtest(13, TAP_RTI);
@@ -212,13 +214,13 @@ int virtex2_handle_read_stat_command(struct command_context_s *cmd_ctx, char *cm
 	pld_device_t *device;
 	virtex2_pld_device_t *virtex2_info;
 	u32 status;
-	
+
 	if (argc < 1)
 	{
 		command_print(cmd_ctx, "usage: virtex2 read_stat <num>");
 		return ERROR_OK;
 	}
-	
+
 	device = get_pld_device_by_num(strtoul(args[0], NULL, 0));
 	if (!device)
 	{
@@ -227,11 +229,11 @@ int virtex2_handle_read_stat_command(struct command_context_s *cmd_ctx, char *cm
 	}
 
 	virtex2_info = device->driver_priv;
-	
+
 	virtex2_read_stat(device, &status);
-	
+
 	command_print(cmd_ctx, "virtex2 status register: 0x%8.8x", status);
-	
+
 	return ERROR_OK;
 }
 
@@ -248,17 +250,17 @@ int virtex2_register_commands(struct command_context_s *cmd_ctx)
 int virtex2_pld_device_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc, struct pld_device_s *pld_device)
 {
 	virtex2_pld_device_t *virtex2_info;
-	
+
 	if (argc < 2)
 	{
 		LOG_WARNING("incomplete pld device 'virtex2' configuration");
 		return ERROR_PLD_DEVICE_INVALID;
 	}
-	
+
 	virtex2_info = malloc(sizeof(virtex2_pld_device_t));
 	pld_device->driver_priv = virtex2_info;
-	
+
 	virtex2_info->chain_pos = strtoul(args[1], NULL, 0);
-	
+
 	return ERROR_OK;
 }
diff --git a/src/target/arm11.c b/src/target/arm11.c
index 4917202..e53f023 100644
--- a/src/target/arm11.c
+++ b/src/target/arm11.c
@@ -710,7 +710,7 @@ int arm11_target_request_data(struct target_s *target, u32 size, u8 *buffer)
 int arm11_halt(struct target_s *target)
 {
 	int retval = ERROR_OK;
-	
+
 	FNC_INFO;
 
 	arm11_common_t * arm11 = target->arch_info;
@@ -1535,6 +1535,8 @@ int arm11_target_create(struct target_s *target, Jim_Interp *interp)
 	}
 
 	jtag_device_t *device = jtag_get_device(target->chain_position);
+	if (device==NULL)
+		return ERROR_FAIL;
 
 	if (device->ir_length != 5)
 	{
diff --git a/src/target/arm11_dbgtap.c b/src/target/arm11_dbgtap.c
index bef62f9..09e8b78 100644
--- a/src/target/arm11_dbgtap.c
+++ b/src/target/arm11_dbgtap.c
@@ -102,6 +102,10 @@ void arm11_setup_field(arm11_common_t * arm11, int num_bits, void * out_data, vo
 void arm11_add_IR(arm11_common_t * arm11, u8 instr, enum tap_state state)
 {
     jtag_device_t *device = jtag_get_device(arm11->jtag_info.chain_pos);
+    if (device==NULL)
+    {
+    	/* FIX!!!! error is logged, but not propagated back up the call stack... */
+    }
 
     if (buf_get_u32(device->cur_instr, 0, 5) == instr)
     {
@@ -139,7 +143,7 @@ static int arm11_in_handler_SCAN_N(u8 *in_value, void *priv, struct scan_field_s
 }
 
 /** Select and write to Scan Chain Register (SCREG)
- * 
+ *
  * This function sets the instruction register to SCAN_N and writes
  * the data register with the selected chain number.
  *
@@ -178,11 +182,11 @@ void arm11_add_debug_SCAN_N(arm11_common_t * arm11, u8 chain, enum tap_state sta
 }
 
 /** Write an instruction into the ITR register
- * 
+ *
  * \param arm11	Target state variable.
  * \param inst	An ARM11 processor instruction/opcode.
  * \param flag	Optional parameter to retrieve the InstCompl flag
- *		(this will be written when the JTAG chain is executed). 
+ *		(this will be written when the JTAG chain is executed).
  * \param state	Pass the final TAP state or -1 for the default
  *		value (Run-Test/Idle).
  *
@@ -212,7 +216,7 @@ void arm11_add_debug_INST(arm11_common_t * arm11, u32 inst, u8 * flag, enum tap_
  *
  * \param arm11 Target state variable.
  * \return DSCR content
- * 
+ *
  * \remarks This is a stand-alone function that executes the JTAG command queue.
  */
 u32 arm11_read_DSCR(arm11_common_t * arm11)
@@ -244,7 +248,7 @@ u32 arm11_read_DSCR(arm11_common_t * arm11)
  *
  * \param arm11 Target state variable.
  * \param dscr DSCR content
- * 
+ *
  * \remarks This is a stand-alone function that executes the JTAG command queue.
  */
 void arm11_write_DSCR(arm11_common_t * arm11, u32 dscr)
@@ -272,7 +276,7 @@ void arm11_write_DSCR(arm11_common_t * arm11, u32 dscr)
  *
  * \param dscr DSCR value to analyze
  * \return Debug reason
- * 
+ *
  */
 enum target_debug_reason arm11_get_DSCR_debug_reason(u32 dscr)
 {
@@ -514,7 +518,7 @@ void arm11_run_instr_data_to_core_noack(arm11_common_t * arm11, u32 opcode, u32
 	{
 	    jtag_add_dr_scan(asizeof(chain5_fields), chain5_fields, TAP_PD);
 	    jtag_add_pathmove(asizeof(arm11_MOVE_PD_RTI_PD_with_delay),
-		arm11_MOVE_PD_RTI_PD_with_delay); 
+		arm11_MOVE_PD_RTI_PD_with_delay);
 	}
 	else
 	{
diff --git a/src/target/arm_jtag.c b/src/target/arm_jtag.c
index 9452c2b..2967f08 100644
--- a/src/target/arm_jtag.c
+++ b/src/target/arm_jtag.c
@@ -39,12 +39,14 @@
 int arm_jtag_set_instr(arm_jtag_t *jtag_info, u32 new_instr,  in_handler_t handler)
 {
 	jtag_device_t *device = jtag_get_device(jtag_info->chain_pos);
-	
+	if (device==NULL)
+		return ERROR_FAIL;
+
 	if (buf_get_u32(device->cur_instr, 0, device->ir_length) != new_instr)
 	{
 		scan_field_t field;
 		u8 t[4];
-	
+
 		field.device = jtag_info->chain_pos;
 		field.num_bits = device->ir_length;
 		field.out_value = t;
@@ -57,7 +59,7 @@ int arm_jtag_set_instr(arm_jtag_t *jtag_info, u32 new_instr,  in_handler_t handl
 		field.in_handler_priv = NULL;
 		jtag_add_ir_scan(1, &field, -1);
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -68,7 +70,7 @@ int arm_jtag_scann(arm_jtag_t *jtag_info, u32 new_scan_chain)
 	{
 		u32 values[1];
 		int num_bits[1];
-		
+
 		values[0]=new_scan_chain;
 		num_bits[0]=jtag_info->scann_size;
 
@@ -82,7 +84,7 @@ int arm_jtag_scann(arm_jtag_t *jtag_info, u32 new_scan_chain)
 				num_bits,
 				values,
 				-1);
-		
+
 		jtag_info->cur_scan_chain = new_scan_chain;
 	}
 
@@ -92,12 +94,12 @@ int arm_jtag_scann(arm_jtag_t *jtag_info, u32 new_scan_chain)
 int arm_jtag_reset_callback(enum jtag_event event, void *priv)
 {
 	arm_jtag_t *jtag_info = priv;
-	
+
 	if (event == JTAG_TRST_ASSERTED)
 	{
 		jtag_info->cur_scan_chain = 0;
 	}
-	
+
 	return ERROR_OK;
 }
 
diff --git a/src/target/etb.c b/src/target/etb.c
index af474e8..05d970d 100644
--- a/src/target/etb.c
+++ b/src/target/etb.c
@@ -63,6 +63,8 @@ int handle_etb_config_command(struct command_context_s *cmd_ctx, char *cmd, char
 int etb_set_instr(etb_t *etb, u32 new_instr)
 {
 	jtag_device_t *device = jtag_get_device(etb->chain_pos);
+	if (device==NULL)
+		return ERROR_FAIL;
 
 	if (buf_get_u32(device->cur_instr, 0, device->ir_length) != new_instr)
 	{
@@ -440,7 +442,6 @@ int handle_etb_config_command(struct command_context_s *cmd_ctx, char *cmd, char
 
 	if (!jtag_device)
 	{
-		LOG_ERROR("jtag device number '%s' not defined", args[1]);
 		return ERROR_FAIL;
 	}
 
diff --git a/src/target/mips_ejtag.c b/src/target/mips_ejtag.c
index 52c710e..4325004 100644
--- a/src/target/mips_ejtag.c
+++ b/src/target/mips_ejtag.c
@@ -35,12 +35,14 @@
 int mips_ejtag_set_instr(mips_ejtag_t *ejtag_info, int new_instr, in_handler_t handler)
 {
 	jtag_device_t *device = jtag_get_device(ejtag_info->chain_pos);
-	
+	if (device==NULL)
+		return ERROR_FAIL;
+
 	if (buf_get_u32(device->cur_instr, 0, device->ir_length) != new_instr)
 	{
 		scan_field_t field;
 		u8 t[4];
-		
+
 		field.device = ejtag_info->chain_pos;
 		field.num_bits = device->ir_length;
 		field.out_value = t;
@@ -53,18 +55,18 @@ int mips_ejtag_set_instr(mips_ejtag_t *ejtag_info, int new_instr, in_handler_t h
 		field.in_handler_priv = NULL;
 		jtag_add_ir_scan(1, &field, -1);
 	}
-	
+
 	return ERROR_OK;
 }
 
 int mips_ejtag_get_idcode(mips_ejtag_t *ejtag_info, u32 *idcode, in_handler_t handler)
 {
 	scan_field_t field;
-	
+
 	jtag_add_end_state(TAP_RTI);
-	
+
 	mips_ejtag_set_instr(ejtag_info, EJTAG_INST_IDCODE, NULL);
-	
+
 	field.device = ejtag_info->chain_pos;
 	field.num_bits = 32;
 	field.out_value = NULL;
@@ -75,23 +77,23 @@ int mips_ejtag_get_idcode(mips_ejtag_t *ejtag_info, u32 *idcode, in_handler_t ha
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
 	jtag_add_dr_scan(1, &field, -1);
-	
+
 	if (jtag_execute_queue() != ERROR_OK)
 	{
 		LOG_ERROR("register read failed");
 	}
-	
+
 	return ERROR_OK;
 }
 
 int mips_ejtag_get_impcode(mips_ejtag_t *ejtag_info, u32 *impcode, in_handler_t handler)
 {
 	scan_field_t field;
-	
+
 	jtag_add_end_state(TAP_RTI);
-	
+
 	mips_ejtag_set_instr(ejtag_info, EJTAG_INST_IMPCODE, NULL);
-	
+
 	field.device = ejtag_info->chain_pos;
 	field.num_bits = 32;
 	field.out_value = NULL;
@@ -102,12 +104,12 @@ int mips_ejtag_get_impcode(mips_ejtag_t *ejtag_info, u32 *impcode, in_handler_t
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
 	jtag_add_dr_scan(1, &field, -1);
-	
+
 	if (jtag_execute_queue() != ERROR_OK)
 	{
 		LOG_ERROR("register read failed");
 	}
-	
+
 	return ERROR_OK;
 }
 
@@ -115,10 +117,13 @@ int mips_ejtag_drscan_32(mips_ejtag_t *ejtag_info, u32 *data)
 {
 	jtag_device_t *device;
 	device = jtag_get_device(ejtag_info->chain_pos);
+
+	if (device==NULL)
+		return ERROR_FAIL;
 	scan_field_t field;
 	u8 t[4];
 	int retval;
-	
+
 	field.device = ejtag_info->chain_pos;
 	field.num_bits = 32;
 	field.out_value = t;
@@ -130,18 +135,18 @@ int mips_ejtag_drscan_32(mips_ejtag_t *ejtag_info, u32 *data)
 	field.in_handler = NULL;
 	field.in_handler_priv = NULL;
 	jtag_add_dr_scan(1, &field, -1);
-	
+
 	if ((retval = jtag_execute_queue()) != ERROR_OK)
 	{
 		LOG_ERROR("register read failed");
 		return retval;
 	}
-	
+
 	return ERROR_OK;
 }
 
 int mips_ejtag_step_enable(mips_ejtag_t *ejtag_info)
-{	
+{
 	u32 code[] = {
 			MIPS32_MTC0(1,31,0),			/* move $1 to COP0 DeSave */
 			MIPS32_MFC0(1,23,0),			/* move COP0 Debug to $1 */
@@ -152,10 +157,10 @@ int mips_ejtag_step_enable(mips_ejtag_t *ejtag_info)
 			MIPS32_B(NEG16(7)),
 			MIPS32_NOP,
 	};
-	
+
 	mips32_pracc_exec(ejtag_info, sizeof(code)/sizeof(code[0]), code, \
 		0, NULL, 0, NULL, 1);
-	
+
 	return ERROR_OK;
 }
 int mips_ejtag_step_disable(mips_ejtag_t *ejtag_info)
@@ -178,17 +183,17 @@ int mips_ejtag_step_disable(mips_ejtag_t *ejtag_info)
 			MIPS32_B(NEG16(15)),
 			MIPS32_NOP,
 	};
-	
+
 	mips32_pracc_exec(ejtag_info, sizeof(code)/sizeof(code[0]), code, \
 		0, NULL, 0, NULL, 1);
-	
+
 	return ERROR_OK;
 }
 
 int mips_ejtag_config_step(mips_ejtag_t *ejtag_info, int enable_step)
-{	
+{
 	if (enable_step)
-		return mips_ejtag_step_enable(ejtag_info);	
+		return mips_ejtag_step_enable(ejtag_info);
 	return mips_ejtag_step_disable(ejtag_info);
 }
 
@@ -197,18 +202,18 @@ int mips_ejtag_enter_debug(mips_ejtag_t *ejtag_info)
 	u32 ejtag_ctrl;
 	jtag_add_end_state(TAP_RTI);
 	mips_ejtag_set_instr(ejtag_info, EJTAG_INST_CONTROL, NULL);
-	
+
 	/* set debug break bit */
 	ejtag_ctrl = ejtag_info->ejtag_ctrl | EJTAG_CTRL_JTAGBRK;
 	mips_ejtag_drscan_32(ejtag_info, &ejtag_ctrl);
-	
+
 	/* break bit will be cleared by hardware */
 	ejtag_ctrl = ejtag_info->ejtag_ctrl;
 	mips_ejtag_drscan_32(ejtag_info, &ejtag_ctrl);
 	LOG_DEBUG("ejtag_ctrl: 0x%8.8x", ejtag_ctrl);
 	if((ejtag_ctrl & EJTAG_CTRL_BRKST) == 0)
 		LOG_DEBUG("Failed to enter Debug Mode!");
-	
+
 	return ERROR_OK;
 }
 
@@ -216,12 +221,12 @@ int mips_ejtag_exit_debug(mips_ejtag_t *ejtag_info, int enable_interrupts)
 {
 	u32 inst;
 	inst = MIPS32_DRET;
-	
+
 	/* TODO : enable/disable interrrupts */
-	
+
 	/* execute our dret instruction */
 	mips32_pracc_exec(ejtag_info, 1, &inst, 0, NULL, 0, NULL, 0);
-	
+
 	return ERROR_OK;
 }
 
@@ -245,23 +250,23 @@ int mips_ejtag_read_debug(mips_ejtag_t *ejtag_info, u32* debug_reg)
 			MIPS32_B(NEG16(14)),
 			MIPS32_NOP,
 	};
-	
+
 	mips32_pracc_exec(ejtag_info, sizeof(code)/sizeof(code[0]), code, \
 		0, NULL, 1, debug_reg, 1);
-	
+
 	return ERROR_OK;
 }
 
 int mips_ejtag_init(mips_ejtag_t *ejtag_info)
 {
 	u32 ejtag_version;
-	
+
 	mips_ejtag_get_impcode(ejtag_info, &ejtag_info->impcode, NULL);
 	LOG_DEBUG("impcode: 0x%8.8x", ejtag_info->impcode);
-	
+
 	/* get ejtag version */
 	ejtag_version = ((ejtag_info->impcode >> 29) & 0x07);
-	
+
 	switch (ejtag_version)
 	{
 		case 0:
@@ -289,12 +294,12 @@ int mips_ejtag_init(mips_ejtag_t *ejtag_info)
 		ejtag_info->impcode & (1<<14) ? " noDMA":  " DMA",
 		ejtag_info->impcode & (1<<0)  ? " MIPS64": " MIPS32"
 	);
-	
+
 	if((ejtag_info->impcode & (1<<14)) == 0)
 		LOG_DEBUG("EJTAG: DMA Access Mode Support Enabled");
-	
+
 	/* set initial state for ejtag control reg */
 	ejtag_info->ejtag_ctrl = EJTAG_CTRL_ROCC | EJTAG_CTRL_PRACC | EJTAG_CTRL_PROBEN | EJTAG_CTRL_SETDEV;
-	
+
 	return ERROR_OK;
 }
diff --git a/src/target/target.c b/src/target/target.c
index 5e8cf74..79c97c2 100644
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -3400,6 +3400,9 @@ target_configure( Jim_GetOptInfo *goi,
 				if( e != JIM_OK ){
 					return e;
 				}
+				if (jtag_get_device(w)==NULL)
+					return JIM_ERR;
+
 				/* make this exactly 1 or 0 */
 				target->chain_position = w;
 			} else {
diff --git a/src/target/xscale.c b/src/target/xscale.c
index 90c8951..ce40c68 100644
--- a/src/target/xscale.c
+++ b/src/target/xscale.c
@@ -215,6 +215,8 @@ int xscale_get_arch_pointers(target_t *target, armv4_5_common_t **armv4_5_p, xsc
 int xscale_jtag_set_instr(int chain_pos, u32 new_instr)
 {
 	jtag_device_t *device = jtag_get_device(chain_pos);
+	if (device==NULL)
+		return ERROR_FAIL;
 
 	if (buf_get_u32(device->cur_instr, 0, device->ir_length) != new_instr)
 	{