Patch from Dimitar Dimitrov adding support for Olimex ARM-JTAG-EW

git-svn-id: svn://svn.berlios.de/openocd/trunk@1402 b42882b7-edfa-0310-969c-e2dbd0fdcd60

4 files changed, 919 insertions, 1 deletions

diff --git a/src/jtag/Makefile.am b/src/jtag/Makefile.am
index 211cedce..717c435d 100644
--- a/src/jtag/Makefile.am
+++ b/src/jtag/Makefile.am
@@ -102,8 +102,14 @@ else
 VSLLINKFILES =
 endif
 
+if ARMJTAGEW
+ARMJTAGEWFILES = arm-jtag-ew.c
+else
+ARMJTAGEWFILES =
+endif
+
 libjtag_a_SOURCES = jtag.c $(BITBANGFILES) $(PARPORTFILES) $(DUMMYFILES) $(FT2232FILES) $(AMTJTAGACCELFILES) $(EP93XXFILES) \
-	$(AT91RM9200FILES) $(GW16012FILES) $(BITQFILES) $(PRESTOFILES) $(USBPROGFILES) $(ECOSBOARDFILES) $(JLINKFILES) $(RLINKFILES) $(VSLLINKFILES)
+	$(AT91RM9200FILES) $(GW16012FILES) $(BITQFILES) $(PRESTOFILES) $(USBPROGFILES) $(ECOSBOARDFILES) $(JLINKFILES) $(RLINKFILES) $(VSLLINKFILES) $(ARMJTAGEWFILES)
 
 noinst_HEADERS = bitbang.h jtag.h bitq.h rlink/dtc_cmd.h rlink/ep1_cmd.h rlink/rlink.h rlink/st7.h
 
diff --git a/src/jtag/arm-jtag-ew.c b/src/jtag/arm-jtag-ew.c
new file mode 100644
index 00000000..f5aa2c95
--- /dev/null
+++ b/src/jtag/arm-jtag-ew.c
@@ -0,0 +1,903 @@
+// vim:ts=4 sw=4: 
+
+/***************************************************************************
+ *   Copyright (C) 2009 by Dimitar Dimitrov <dinuxbg@gmail.com>            *
+ *   based on Dominic Rath's and Benedikt Sauter's usbprog.c               *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "replacements.h"
+
+#include "jtag.h"
+#include <usb.h>
+#include <string.h>
+#include <ctype.h>
+
+/* system includes */
+
+#include "log.h"
+
+/* enable this to debug communication
+ */
+#if 1
+#define _DEBUG_USB_COMMS_
+#define _DEBUG_JTAG_IO_
+#endif
+
+#ifdef _DEBUG_JTAG_IO_
+#define DEBUG_JTAG_IO(expr ...)	LOG_DEBUG(expr)
+#else
+#define DEBUG_JTAG_IO(expr ...)
+#endif
+
+#define USB_VID						0x15ba
+#define USB_PID						0x001e
+
+#define ARMJTAGEW_EPT_BULK_OUT		0x01u
+#define ARMJTAGEW_EPT_BULK_IN		0x82u
+
+#define ARMJTAGEW_USB_TIMEOUT		2000
+
+#define ARMJTAGEW_IN_BUFFER_SIZE	(4*1024)
+#define ARMJTAGEW_OUT_BUFFER_SIZE	(4*1024)
+
+
+/* USB command request codes. */
+#define CMD_GET_VERSION				0x00
+#define CMD_SELECT_DPIMPL			0x10
+#define CMD_SET_TCK_FREQUENCY		0x11
+#define CMD_GET_TCK_FREQUENCY		0x12
+#define CMD_MEASURE_MAX_TCK_FREQ	0x15
+#define CMD_MEASURE_RTCK_RESPONSE	0x16
+#define CMD_TAP_SHIFT				0x17
+#define CMD_SET_TAPHW_STATE			0x20
+#define CMD_GET_TAPHW_STATE			0x21
+#define CMD_TGPWR_SETUP				0x22
+
+/* Global USB buffers */
+static u8 usb_in_buffer[ARMJTAGEW_IN_BUFFER_SIZE];
+static u8 usb_out_buffer[ARMJTAGEW_OUT_BUFFER_SIZE];
+
+/* External interface functions */
+int armjtagew_execute_queue(void);
+int armjtagew_speed(int speed);
+int armjtagew_khz(int khz, int *jtag_speed);
+int armjtagew_register_commands(struct command_context_s *cmd_ctx);
+int armjtagew_init(void);
+int armjtagew_quit(void);
+
+/* CLI command handler functions */
+int armjtagew_handle_armjtagew_info_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
+
+/* Queue command functions */
+void armjtagew_end_state(tap_state_t state);
+void armjtagew_state_move(void);
+void armjtagew_path_move(int num_states, tap_state_t *path);
+void armjtagew_runtest(int num_cycles);
+void armjtagew_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size, scan_command_t *command);
+void armjtagew_reset(int trst, int srst);
+void armjtagew_simple_command(u8 command);
+int armjtagew_get_status(void);
+
+/* tap buffer functions */
+void armjtagew_tap_init(void);
+int armjtagew_tap_execute(void);
+void armjtagew_tap_ensure_space(int scans, int bits);
+void armjtagew_tap_append_step(int tms, int tdi);
+void armjtagew_tap_append_scan(int length, u8 *buffer, scan_command_t *command);
+
+/* ARM-JTAG-EW lowlevel functions */
+typedef struct armjtagew_jtag
+{
+	struct usb_dev_handle* usb_handle;
+} armjtagew_jtag_t;
+
+armjtagew_jtag_t *armjtagew_usb_open(void);
+void armjtagew_usb_close(armjtagew_jtag_t *armjtagew_jtag);
+int armjtagew_usb_message(armjtagew_jtag_t *armjtagew_jtag, int out_length, int in_length);
+int armjtagew_usb_write(armjtagew_jtag_t *armjtagew_jtag, int out_length);
+int armjtagew_usb_read(armjtagew_jtag_t *armjtagew_jtag, int exp_in_length);
+
+/* helper functions */
+int armjtagew_get_version_info(void);
+
+#ifdef _DEBUG_USB_COMMS_
+void armjtagew_debug_buffer(u8 *buffer, int length);
+#endif
+
+armjtagew_jtag_t* armjtagew_jtag_handle;
+
+
+
+/***************************************************************************/
+/* External interface implementation */
+
+jtag_interface_t armjtagew_interface =
+{
+	.name = "arm-jtag-ew",
+	.execute_queue = armjtagew_execute_queue,
+	.speed = armjtagew_speed,
+	.khz = armjtagew_khz,
+	.register_commands = armjtagew_register_commands,
+	.init = armjtagew_init,
+	.quit = armjtagew_quit
+};
+
+
+int armjtagew_execute_queue(void)
+{
+	jtag_command_t *cmd = jtag_command_queue;
+	int scan_size;
+	enum scan_type type;
+	u8 *buffer;
+
+	while (cmd != NULL)
+	{
+		switch (cmd->type)
+		{
+			case JTAG_END_STATE:
+				DEBUG_JTAG_IO("end_state: %i", cmd->cmd.end_state->end_state);
+
+				if (cmd->cmd.end_state->end_state != -1)
+				{
+					armjtagew_end_state(cmd->cmd.end_state->end_state);
+				}
+				break;
+
+			case JTAG_RUNTEST:
+				DEBUG_JTAG_IO( "runtest %i cycles, end in %i", cmd->cmd.runtest->num_cycles, \
+					cmd->cmd.runtest->end_state);
+
+				if (cmd->cmd.runtest->end_state != -1)
+				{
+					armjtagew_end_state(cmd->cmd.runtest->end_state);
+				}
+				armjtagew_runtest(cmd->cmd.runtest->num_cycles);
+				break;
+
+			case JTAG_STATEMOVE:
+				DEBUG_JTAG_IO("statemove end in %i", cmd->cmd.statemove->end_state);
+
+				if (cmd->cmd.statemove->end_state != -1)
+				{
+					armjtagew_end_state(cmd->cmd.statemove->end_state);
+				}
+				armjtagew_state_move();
+				break;
+
+			case JTAG_PATHMOVE:
+				DEBUG_JTAG_IO("pathmove: %i states, end in %i", \
+					cmd->cmd.pathmove->num_states, \
+					cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]);
+
+				armjtagew_path_move(cmd->cmd.pathmove->num_states, cmd->cmd.pathmove->path);
+				break;
+
+			case JTAG_SCAN:
+				DEBUG_JTAG_IO("scan end in %i", cmd->cmd.scan->end_state);
+
+				if (cmd->cmd.scan->end_state != -1)
+				{
+					armjtagew_end_state(cmd->cmd.scan->end_state);
+				}
+
+				scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
+				DEBUG_JTAG_IO("scan input, length = %d", scan_size);
+
+#ifdef _DEBUG_USB_COMMS_
+				armjtagew_debug_buffer(buffer, (scan_size + 7) / 8);
+#endif
+				type = jtag_scan_type(cmd->cmd.scan);
+				armjtagew_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size, cmd->cmd.scan);
+				break;
+
+			case JTAG_RESET:
+				DEBUG_JTAG_IO("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
+
+				armjtagew_tap_execute();
+
+				if (cmd->cmd.reset->trst == 1)
+				{
+					tap_set_state(TAP_RESET);
+				}
+				armjtagew_reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
+				break;
+
+			case JTAG_SLEEP:
+				DEBUG_JTAG_IO("sleep %i", cmd->cmd.sleep->us);
+				armjtagew_tap_execute();
+				jtag_sleep(cmd->cmd.sleep->us);
+				break;
+
+			default:
+				LOG_ERROR("BUG: unknown JTAG command type encountered");
+				exit(-1);
+		}
+		cmd = cmd->next;
+	}
+
+	return armjtagew_tap_execute();
+}
+
+
+/* Sets speed in kHz. */
+int armjtagew_speed(int speed)
+{
+    int result;
+    int speed_real;
+
+
+    usb_out_buffer[0] = CMD_SET_TCK_FREQUENCY;
+	buf_set_u32(usb_out_buffer+1, 0, 32, speed);
+
+    result = armjtagew_usb_message(armjtagew_jtag_handle, 4, 4);
+
+    if (result < 0)
+    {
+        LOG_ERROR("ARM-JTAG-EW setting speed failed (%d)", result);
+        return ERROR_JTAG_DEVICE_ERROR;
+    }
+
+	usb_out_buffer[0] = CMD_GET_TCK_FREQUENCY;
+    result = armjtagew_usb_message(armjtagew_jtag_handle, 1, 4);
+	speed_real = (int)buf_get_u32(usb_in_buffer,0,32);
+	if(result < 0) 
+	{
+        LOG_ERROR("ARM-JTAG-EW getting speed failed (%d)", result);
+        return ERROR_JTAG_DEVICE_ERROR;
+	} 
+	else
+	{
+    	LOG_INFO("Requested speed %dkHz, emulator reported %dkHz.", speed, speed_real);
+	}
+
+    return ERROR_OK;
+}
+
+
+int armjtagew_khz(int khz, int *jtag_speed)
+{
+	*jtag_speed = khz;
+
+	return ERROR_OK;
+}
+
+int armjtagew_register_commands(struct command_context_s *cmd_ctx)
+{
+	register_command(cmd_ctx, NULL, "armjtagew_info", armjtagew_handle_armjtagew_info_command, COMMAND_EXEC,
+		"query armjtagew info");
+	return ERROR_OK;
+}
+
+int armjtagew_init(void)
+{
+	int check_cnt;
+
+	armjtagew_jtag_handle = armjtagew_usb_open();
+
+	if (armjtagew_jtag_handle == 0)
+	{
+		LOG_ERROR("Cannot find ARM-JTAG-EW Interface! Please check connection and permissions.");
+		return ERROR_JTAG_INIT_FAILED;
+	}
+
+	check_cnt = 0;
+	while (check_cnt < 3)
+	{
+		if (armjtagew_get_version_info() == ERROR_OK)
+		{
+			/* attempt to get status */
+			armjtagew_get_status();
+			break;
+		}
+
+		check_cnt++;
+	}
+
+	if (check_cnt == 3)
+	{
+		LOG_INFO("ARM-JTAG-EW initial read failed, don't worry");
+	}
+
+	LOG_INFO("ARM-JTAG-EW JTAG Interface ready");
+
+	armjtagew_reset(0, 0);
+	armjtagew_tap_init();
+
+	return ERROR_OK;
+}
+
+int armjtagew_quit(void)
+{
+	armjtagew_usb_close(armjtagew_jtag_handle);
+	return ERROR_OK;
+}
+
+/***************************************************************************/
+/* Queue command implementations */
+
+void armjtagew_end_state(tap_state_t state)
+{
+	if (tap_is_state_stable(state))
+	{
+		tap_set_end_state(state);
+	}
+	else
+	{
+		LOG_ERROR("BUG: %i is not a valid end state", state);
+		exit(-1);
+	}
+}
+
+/* Goes to the end state. */
+void armjtagew_state_move(void)
+{
+	int i;
+	int tms = 0;
+	u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
+
+	for (i = 0; i < 7; i++)
+	{
+		tms = (tms_scan >> i) & 1;
+		armjtagew_tap_append_step(tms, 0);
+	}
+
+	tap_set_state(tap_get_end_state());
+}
+
+void armjtagew_path_move(int num_states, tap_state_t *path)
+{
+	int i;
+
+	for (i = 0; i < num_states; i++)
+	{
+		/*
+		 * TODO: The ARM-JTAG-EW hardware delays TDI with 3 TCK cycles when in RTCK mode. 
+		 * Either handle that here, or update the documentation with examples
+		 * how to fix that in the configuration files.
+		 */
+		if (path[i] == tap_state_transition(tap_get_state(), false))
+		{
+			armjtagew_tap_append_step(0, 0);
+		}
+		else if (path[i] == tap_state_transition(tap_get_state(), true))
+		{
+			armjtagew_tap_append_step(1, 0);
+		}
+		else
+		{
+			LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(path[i]));
+			exit(-1);
+		}
+
+		tap_set_state(path[i]);
+	}
+
+	tap_set_end_state(tap_get_state());
+}
+
+void armjtagew_runtest(int num_cycles)
+{
+	int i;
+
+	tap_state_t saved_end_state = tap_get_end_state();
+
+	/* only do a state_move when we're not already in IDLE */
+	if (tap_get_state() != TAP_IDLE)
+	{
+		armjtagew_end_state(TAP_IDLE);
+		armjtagew_state_move();
+	}
+
+	/* execute num_cycles */
+	for (i = 0; i < num_cycles; i++)
+	{
+		armjtagew_tap_append_step(0, 0);
+	}
+
+	/* finish in end_state */
+	armjtagew_end_state(saved_end_state);
+	if (tap_get_state() != tap_get_end_state())
+	{
+		armjtagew_state_move();
+	}
+}
+
+void armjtagew_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size, scan_command_t *command)
+{
+	tap_state_t saved_end_state;
+
+	armjtagew_tap_ensure_space(1, scan_size + 8);
+
+	saved_end_state = tap_get_end_state();
+
+	/* Move to appropriate scan state */
+	armjtagew_end_state(ir_scan ? TAP_IRSHIFT : TAP_DRSHIFT);
+
+	armjtagew_state_move();
+	armjtagew_end_state(saved_end_state);
+
+	/* Scan */
+	armjtagew_tap_append_scan(scan_size, buffer, command);
+
+	/* We are in Exit1, go to Pause */
+	armjtagew_tap_append_step(0, 0);
+
+	tap_set_state(ir_scan ? TAP_IRPAUSE : TAP_DRPAUSE);
+
+	if (tap_get_state() != tap_get_end_state())
+	{
+		armjtagew_state_move();
+	}
+}
+
+void armjtagew_reset(int trst, int srst)
+{
+	const u8 trst_mask = (1u<<5);
+	const u8 srst_mask = (1u<<6);
+	u8 val = 0;
+	u8 outp_en = 0;
+	u8 change_mask = 0;
+	int result;
+
+	LOG_DEBUG("trst: %i, srst: %i", trst, srst);
+
+	if (srst == 0)
+	{
+		val |= srst_mask;
+		outp_en &= ~srst_mask;		/* tristate */
+		change_mask |= srst_mask;
+	}
+	else if (srst == 1)
+	{
+		val &= ~srst_mask;
+		outp_en |= srst_mask;
+		change_mask |= srst_mask;
+	}
+
+	if (trst == 0)
+	{
+		val |= trst_mask;
+		outp_en &= ~trst_mask;		/* tristate */
+		change_mask |= trst_mask;
+	}
+	else if (trst == 1)
+	{
+		val &= ~trst_mask;
+		outp_en |= trst_mask;
+		change_mask |= trst_mask;
+	}
+
+	usb_out_buffer[0] = CMD_SET_TAPHW_STATE;
+	usb_out_buffer[1] = val;
+	usb_out_buffer[2] = outp_en;
+	usb_out_buffer[3] = change_mask;
+	result = armjtagew_usb_write(armjtagew_jtag_handle, 4);
+	if (result != 4)
+	{
+		LOG_ERROR("ARM-JTAG-EW TRST/SRST pin set failed failed (%d)", result);
+	}
+}
+
+
+int armjtagew_get_status(void)
+{
+	int result;
+
+	usb_out_buffer[0] = CMD_GET_TAPHW_STATE;
+	result = armjtagew_usb_message(armjtagew_jtag_handle, 1, 12);
+
+	if (result == 0)
+	{
+		unsigned int u_tg = buf_get_u32(usb_in_buffer, 0, 16);
+		LOG_INFO("U_tg = %d mV, U_aux = %d mV, U_tgpwr = %d mV, I_tgpwr = %d mA, D1 = %d, Target power %s %s\n", \
+			buf_get_u32(usb_in_buffer + 0, 0, 16), \
+			buf_get_u32(usb_in_buffer + 2, 0, 16), \
+			buf_get_u32(usb_in_buffer + 4, 0, 16), \
+			buf_get_u32(usb_in_buffer + 6, 0, 16), \
+			usb_in_buffer[9], \
+			usb_in_buffer[11] ? "OVERCURRENT" : "OK", \
+			usb_in_buffer[10] ? "enabled" : "disabled");
+
+		if (u_tg < 1500)
+		{
+			LOG_ERROR("Vref too low. Check Target Power\n");
+		}
+	}
+	else
+	{
+		LOG_ERROR("ARM-JTAG-EW command CMD_GET_TAPHW_STATE failed (%d)\n", result);
+	}
+
+	return ERROR_OK;
+}
+
+int armjtagew_get_version_info(void)
+{
+	int result;
+	char sn[16];
+	char auxinfo[257];
+
+	/* query hardware version */
+	usb_out_buffer[0] = CMD_GET_VERSION;
+	result = armjtagew_usb_message(armjtagew_jtag_handle, 1, 4+15+256);
+
+	if (result != 0) 
+	{
+		LOG_ERROR("ARM-JTAG-EW command CMD_GET_VERSION failed (%d)\n", result);
+		return ERROR_JTAG_DEVICE_ERROR;
+	}
+
+
+	memcpy(sn, usb_in_buffer+4, 15);
+	sn[15] = '\0';
+	memcpy(auxinfo, usb_in_buffer+4+15, 256);
+	auxinfo[256] = '\0';
+
+	LOG_INFO("ARM-JTAG-EW firmware version %d.%d, hardware revision %c, SN=%s, Additional info: %s", \
+			usb_in_buffer[1], usb_in_buffer[0], \
+			isgraph(usb_in_buffer[2]) ? usb_in_buffer[2] : 'X', \
+			sn, auxinfo);
+	return ERROR_OK;
+}
+
+int armjtagew_handle_armjtagew_info_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
+{
+	if (armjtagew_get_version_info() == ERROR_OK)
+	{
+		/* attempt to get status */
+		armjtagew_get_status();
+	}
+
+	return ERROR_OK;
+}
+
+/***************************************************************************/
+/* ARM-JTAG-EW tap functions */
+
+/* 2048 is the max value we can use here */
+#define ARMJTAGEW_TAP_BUFFER_SIZE 2048
+
+static int tap_length;
+static u8 tms_buffer[ARMJTAGEW_TAP_BUFFER_SIZE];
+static u8 tdi_buffer[ARMJTAGEW_TAP_BUFFER_SIZE];
+static u8 tdo_buffer[ARMJTAGEW_TAP_BUFFER_SIZE];
+
+typedef struct
+{
+	int first;	/* First bit position in tdo_buffer to read */
+	int length; /* Number of bits to read */
+	scan_command_t *command; /* Corresponding scan command */
+	u8 *buffer;
+} pending_scan_result_t;
+
+#define MAX_PENDING_SCAN_RESULTS 256
+
+static int pending_scan_results_length;
+static pending_scan_result_t pending_scan_results_buffer[MAX_PENDING_SCAN_RESULTS];
+
+static int last_tms;
+
+void armjtagew_tap_init(void)
+{
+	tap_length = 0;
+	pending_scan_results_length = 0;
+}
+
+void armjtagew_tap_ensure_space(int scans, int bits)
+{
+	int available_scans = MAX_PENDING_SCAN_RESULTS - pending_scan_results_length;
+	int available_bits = ARMJTAGEW_TAP_BUFFER_SIZE * 8 - tap_length;
+
+	if (scans > available_scans || bits > available_bits)
+	{
+		armjtagew_tap_execute();
+	}
+}
+
+void armjtagew_tap_append_step(int tms, int tdi)
+{
+	last_tms = tms;
+	int index = tap_length / 8;
+
+	if (index < ARMJTAGEW_TAP_BUFFER_SIZE)
+	{
+		int bit_index = tap_length % 8;
+		u8 bit = 1 << bit_index;
+
+		if (tms)
+		{
+			tms_buffer[index] |= bit;
+		}
+		else
+		{
+			tms_buffer[index] &= ~bit;
+		}
+
+		if (tdi)
+		{
+			tdi_buffer[index] |= bit;
+		}
+		else
+		{
+			tdi_buffer[index] &= ~bit;
+		}
+
+		tap_length++;
+	}
+	else
+	{
+		LOG_ERROR("armjtagew_tap_append_step, overflow");
+	}
+}
+
+void armjtagew_tap_append_scan(int length, u8 *buffer, scan_command_t *command)
+{
+	pending_scan_result_t *pending_scan_result = &pending_scan_results_buffer[pending_scan_results_length];
+	int i;
+
+	pending_scan_result->first = tap_length;
+	pending_scan_result->length = length;
+	pending_scan_result->command = command;
+	pending_scan_result->buffer = buffer;
+
+	for (i = 0; i < length; i++)
+	{
+		armjtagew_tap_append_step((i < length-1 ? 0 : 1), (buffer[i/8] >> (i%8)) & 1);
+	}
+	pending_scan_results_length++;
+}
+
+/* Pad and send a tap sequence to the device, and receive the answer.
+ * For the purpose of padding we assume that we are in idle or pause state. */
+int armjtagew_tap_execute(void)
+{
+	int byte_length;
+	int tms_offset;
+	int tdi_offset;
+	int i;
+	int result;
+
+	if (tap_length > 0)
+	{
+		/* Pad last byte so that tap_length is divisible by 8 */
+		while (tap_length % 8 != 0)
+		{
+			/* More of the last TMS value keeps us in the same state,
+			 * analogous to free-running JTAG interfaces. */
+			armjtagew_tap_append_step(last_tms, 0);
+		}
+
+		byte_length = tap_length / 8;
+
+		usb_out_buffer[0] = CMD_TAP_SHIFT;
+		buf_set_u32(usb_out_buffer+1, 0, 16, byte_length);
+
+		tms_offset = 3;
+		for (i = 0; i < byte_length; i++)
+		{
+			usb_out_buffer[tms_offset + i] = flip_u32(tms_buffer[i],8);
+		}
+
+		tdi_offset = tms_offset + byte_length;
+		for (i = 0; i < byte_length; i++)
+		{
+			usb_out_buffer[tdi_offset + i] = flip_u32(tdi_buffer[i],8);
+		}
+
+		result = armjtagew_usb_message(armjtagew_jtag_handle, 3 + 2 * byte_length, byte_length + 4);
+
+		if (result == 0)
+		{
+			int stat;
+
+			stat = (int)buf_get_u32(usb_in_buffer + byte_length, 0, 32);
+			if(stat) {
+				LOG_ERROR("armjtagew_tap_execute, emulator returned error code %d for a CMD_TAP_SHIFT command", stat);
+				return ERROR_JTAG_QUEUE_FAILED;
+			}
+
+			for (i = 0; i < byte_length; i++)
+			{
+				tdo_buffer[i] = flip_u32(usb_in_buffer[i],8);
+			}
+
+			for (i = 0; i < pending_scan_results_length; i++)
+			{
+				pending_scan_result_t *pending_scan_result = &pending_scan_results_buffer[i];
+				u8 *buffer = pending_scan_result->buffer;
+				int length = pending_scan_result->length;
+				int first = pending_scan_result->first;
+				scan_command_t *command = pending_scan_result->command;
+
+				/* Copy to buffer */
+				buf_set_buf(tdo_buffer, first, buffer, 0, length);
+
+				DEBUG_JTAG_IO("pending scan result, length = %d", length);
+
+#ifdef _DEBUG_USB_COMMS_
+				armjtagew_debug_buffer(buffer, byte_length);
+#endif
+
+				if (jtag_read_buffer(buffer, command) != ERROR_OK)
+				{
+					armjtagew_tap_init();
+					return ERROR_JTAG_QUEUE_FAILED;
+				}
+
+				if (pending_scan_result->buffer != NULL)
+				{
+					free(pending_scan_result->buffer);
+				}
+			}
+		}
+		else
+		{
+			LOG_ERROR("armjtagew_tap_execute, wrong result %d, expected %d", result, byte_length);
+			return ERROR_JTAG_QUEUE_FAILED;
+		}
+
+		armjtagew_tap_init();
+	}
+
+	return ERROR_OK;
+}
+
+/*****************************************************************************/
+/* JLink USB low-level functions */
+
+armjtagew_jtag_t* armjtagew_usb_open()
+{
+	struct usb_bus *busses;
+	struct usb_bus *bus;
+	struct usb_device *dev;
+
+	armjtagew_jtag_t *result;
+
+	result = (armjtagew_jtag_t*) malloc(sizeof(armjtagew_jtag_t));
+
+	usb_init();
+	usb_find_busses();
+	usb_find_devices();
+
+	busses = usb_get_busses();
+
+	/* find armjtagew_jtag device in usb bus */
+
+	for (bus = busses; bus; bus = bus->next)
+	{
+		for (dev = bus->devices; dev; dev = dev->next)
+		{
+			if ((dev->descriptor.idVendor == USB_VID) && (dev->descriptor.idProduct == USB_PID))
+			{
+				result->usb_handle = usb_open(dev);
+
+#if 0
+				/* usb_set_configuration required under win32 */
+				usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
+#endif
+				usb_claim_interface(result->usb_handle, 0);
+
+#if 0
+				/*
+				 * This makes problems under Mac OS X. And is not needed
+				 * under Windows. Hopefully this will not break a linux build
+				 */
+				usb_set_altinterface(result->usb_handle, 0);
+#endif
+				return result;
+			}
+		}
+	}
+
+	free(result);
+	return NULL;
+}
+
+void armjtagew_usb_close(armjtagew_jtag_t *armjtagew_jtag)
+{
+	usb_close(armjtagew_jtag->usb_handle);
+	free(armjtagew_jtag);
+}
+
+/* Send a message and receive the reply. */
+int armjtagew_usb_message(armjtagew_jtag_t *armjtagew_jtag, int out_length, int in_length)
+{
+	int result;
+
+	result = armjtagew_usb_write(armjtagew_jtag, out_length);
+	if (result == out_length)
+	{
+		result = armjtagew_usb_read(armjtagew_jtag, in_length);
+		if (result != in_length) 
+		{
+			LOG_ERROR("usb_bulk_read failed (requested=%d, result=%d)", in_length, result);
+			return -1;
+		}
+	}
+	else
+	{
+		LOG_ERROR("usb_bulk_write failed (requested=%d, result=%d)", out_length, result);
+		return -1;
+	}
+	return 0;
+}
+
+/* Write data from out_buffer to USB. */
+int armjtagew_usb_write(armjtagew_jtag_t *armjtagew_jtag, int out_length)
+{
+	int result;
+
+	if (out_length > ARMJTAGEW_OUT_BUFFER_SIZE)
+	{
+		LOG_ERROR("armjtagew_jtag_write illegal out_length=%d (max=%d)", out_length, ARMJTAGEW_OUT_BUFFER_SIZE);
+		return -1;
+	}
+
+	result = usb_bulk_write(armjtagew_jtag->usb_handle, ARMJTAGEW_EPT_BULK_OUT, \
+		(char*)usb_out_buffer, out_length, ARMJTAGEW_USB_TIMEOUT);
+
+	DEBUG_JTAG_IO("armjtagew_usb_write, out_length = %d, result = %d", out_length, result);
+
+#ifdef _DEBUG_USB_COMMS_
+	armjtagew_debug_buffer(usb_out_buffer, out_length);
+#endif
+	return result;
+}
+
+/* Read data from USB into in_buffer. */
+int armjtagew_usb_read(armjtagew_jtag_t *armjtagew_jtag, int exp_in_length)
+{
+	int result = usb_bulk_read(armjtagew_jtag->usb_handle, ARMJTAGEW_EPT_BULK_IN, \
+		(char*)usb_in_buffer, exp_in_length, ARMJTAGEW_USB_TIMEOUT);
+
+	DEBUG_JTAG_IO("armjtagew_usb_read, result = %d", result);
+
+#ifdef _DEBUG_USB_COMMS_
+	armjtagew_debug_buffer(usb_in_buffer, result);
+#endif
+	return result;
+}
+
+
+#ifdef _DEBUG_USB_COMMS_
+#define BYTES_PER_LINE  16
+
+void armjtagew_debug_buffer(u8 *buffer, int length)
+{
+	char line[81];
+	char s[4];
+	int i;
+	int j;
+
+	for (i = 0; i < length; i += BYTES_PER_LINE)
+	{
+		snprintf(line, 5, "%04x", i);
+		for (j = i; j < i + BYTES_PER_LINE && j < length; j++)
+		{
+			snprintf(s, 4, " %02x", buffer[j]);
+			strcat(line, s);
+		}
+		LOG_DEBUG(line);
+	}
+}
+#endif
+
diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index ae51ebc1..4e8b11d7 100644
--- a/src/jtag/jtag.c
+++ b/src/jtag/jtag.c
@@ -155,6 +155,10 @@ static int hasKHz = 0;
 	extern jtag_interface_t rlink_interface;
 #endif
 
+#if BUILD_ARMJTAGEW == 1
+	extern jtag_interface_t armjtagew_interface;
+#endif
+
 jtag_interface_t *jtag_interfaces[] = {
 #if BUILD_ECOSBOARD == 1
 	&zy1000_interface,
@@ -198,6 +202,9 @@ jtag_interface_t *jtag_interfaces[] = {
 #if BUILD_RLINK == 1
 	&rlink_interface,
 #endif
+#if BUILD_ARMJTAGEW == 1
+	&armjtagew_interface,
+#endif
 	NULL,
 };
 
diff --git a/src/target/interface/arm-jtag-ew.cfg b/src/target/interface/arm-jtag-ew.cfg
new file mode 100644
index 00000000..1f9d3d99
--- /dev/null
+++ b/src/target/interface/arm-jtag-ew.cfg
@@ -0,0 +1,2 @@
+# Interface ARM-JTAG-EW
+interface arm-jtag-ew