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

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));

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;
 		}
 	}

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;
 }

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)
 	{

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
 	{

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;
 }
 

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;
 	}
 

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;
 }

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 {

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)
 	{