X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=blobdiff_plain;f=src%2Fjtag%2Fjlink.c;h=23ebc62d2a6431dbfc383500e336a7cacda94ed6;hp=10563a0d9063defd7835a17fe3e4dad2b9ea4ee6;hb=0535a9245632e2cf12d8eaae8c4a9b1cc0bc66c6;hpb=10923655d65eb773d0ad9e7b76ff3871bb546628

diff --git a/src/jtag/jlink.c b/src/jtag/jlink.c
index 10563a0d90..23ebc62d2a 100644
--- a/src/jtag/jlink.c
+++ b/src/jtag/jlink.c
@@ -25,7 +25,8 @@
 #include "config.h"
 #endif
 
-#include "jtag.h"
+#include "interface.h"
+#include "commands.h"
 
 #include <usb.h>
 
@@ -36,6 +37,10 @@
 #define JLINK_WRITE_ENDPOINT	0x02
 #define JLINK_READ_ENDPOINT		0x81
 
+static unsigned int jlink_write_ep = JLINK_WRITE_ENDPOINT;
+static unsigned int jlink_read_ep = JLINK_READ_ENDPOINT;
+static unsigned int jlink_hw_jtag_version = 2;
+
 #define JLINK_USB_TIMEOUT		1000
 
 // See Section 1.3.2 of the Segger JLink USB protocol manual
@@ -45,28 +50,34 @@
 //#define JLINK_TAP_BUFFER_SIZE 384
 
 #define JLINK_IN_BUFFER_SIZE			2048
-#define JLINK_OUT_BUFFER_SIZE			2*2048+4
+#define JLINK_OUT_BUFFER_SIZE			2*2048 + 4
 #define JLINK_EMU_RESULT_BUFFER_SIZE	64
 
 /* Global USB buffers */
-static u8 usb_in_buffer[JLINK_IN_BUFFER_SIZE];
-static u8 usb_out_buffer[JLINK_OUT_BUFFER_SIZE];
-static u8 usb_emu_result_buffer[JLINK_EMU_RESULT_BUFFER_SIZE];
+static uint8_t usb_in_buffer[JLINK_IN_BUFFER_SIZE];
+static uint8_t usb_out_buffer[JLINK_OUT_BUFFER_SIZE];
+static uint8_t usb_emu_result_buffer[JLINK_EMU_RESULT_BUFFER_SIZE];
 
 /* Constants for JLink command */
-#define EMU_CMD_VERSION     		0x01
-#define EMU_CMD_SET_SPEED   		0x05
-#define EMU_CMD_GET_STATE   		0x07
+#define EMU_CMD_VERSION		0x01
+#define EMU_CMD_SET_SPEED		0x05
+#define EMU_CMD_GET_STATE		0x07
 #define EMU_CMD_HW_CLOCK			0xc8
-#define EMU_CMD_HW_TMS0 			0xc9
-#define EMU_CMD_HW_TMS1 			0xca
-#define EMU_CMD_HW_JTAG3    		0xcf
+#define EMU_CMD_HW_TMS0			0xc9
+#define EMU_CMD_HW_TMS1			0xca
+#define EMU_CMD_HW_JTAG2		0xce
+#define EMU_CMD_HW_JTAG3		0xcf
 #define EMU_CMD_GET_MAX_MEM_BLOCK	0xd4
-#define EMU_CMD_HW_RESET0   		0xdc
-#define EMU_CMD_HW_RESET1   		0xdd
-#define EMU_CMD_HW_TRST0    		0xde
-#define EMU_CMD_HW_TRST1    		0xdf
-#define EMU_CMD_GET_CAPS    		0xe8
+#define EMU_CMD_HW_RESET0		0xdc
+#define EMU_CMD_HW_RESET1		0xdd
+#define EMU_CMD_HW_TRST0		0xde
+#define EMU_CMD_HW_TRST1		0xdf
+#define EMU_CMD_GET_CAPS		0xe8
+#define EMU_CMD_GET_HW_VERSION	0xf0
+
+/* bits return from EMU_CMD_GET_CAPS */
+#define EMU_CAP_GET_HW_VERSION		1
+#define EMU_CAP_GET_MAX_BLOCK_SIZE	11
 
 /* max speed 12MHz v5.0 jlink */
 #define JLINK_MAX_SPEED 12000
@@ -76,21 +87,18 @@ static int jlink_execute_queue(void);
 static int jlink_speed(int speed);
 static int jlink_speed_div(int speed, int* khz);
 static int jlink_khz(int khz, int *jtag_speed);
-static int jlink_register_commands(struct command_context_s *cmd_ctx);
+static int jlink_register_commands(struct command_context *cmd_ctx);
 static int jlink_init(void);
 static int jlink_quit(void);
 
-/* CLI command handler functions */
-static int jlink_handle_jlink_info_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
-
 /* Queue command functions */
 static void jlink_end_state(tap_state_t state);
 static void jlink_state_move(void);
 static void jlink_path_move(int num_states, tap_state_t *path);
 static void jlink_runtest(int num_cycles);
-static void jlink_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size, scan_command_t *command);
+static void jlink_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size, struct scan_command *command);
 static void jlink_reset(int trst, int srst);
-static void jlink_simple_command(u8 command);
+static void jlink_simple_command(uint8_t command);
 static int jlink_get_status(void);
 
 /* J-Link tap buffer functions */
@@ -98,36 +106,35 @@ static void jlink_tap_init(void);
 static int jlink_tap_execute(void);
 static void jlink_tap_ensure_space(int scans, int bits);
 static void jlink_tap_append_step(int tms, int tdi);
-static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *command);
+static void jlink_tap_append_scan(int length, uint8_t *buffer, struct scan_command *command);
 
 /* Jlink lowlevel functions */
-typedef struct jlink_jtag
-{
+struct jlink {
 	struct usb_dev_handle* usb_handle;
-} jlink_jtag_t;
+};
 
-static jlink_jtag_t *jlink_usb_open(void);
-static void jlink_usb_close(jlink_jtag_t *jlink_jtag);
-static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_length);
-static int jlink_usb_write(jlink_jtag_t *jlink_jtag, int out_length);
-static int jlink_usb_read(jlink_jtag_t *jlink_jtag, int expected_size);
-static int jlink_usb_read_emu_result(jlink_jtag_t *jlink_jtag);
+static struct jlink *jlink_usb_open(void);
+static void jlink_usb_close(struct jlink *jlink);
+static int jlink_usb_message(struct jlink *jlink, int out_length, int in_length);
+static int jlink_usb_write(struct jlink *jlink, int out_length);
+static int jlink_usb_read(struct jlink *jlink, int expected_size);
+static int jlink_usb_read_emu_result(struct jlink *jlink);
 
 /* helper functions */
 static int jlink_get_version_info(void);
 
 #ifdef _DEBUG_USB_COMMS_
-static void jlink_debug_buffer(u8 *buffer, int length);
+static void jlink_debug_buffer(uint8_t *buffer, int length);
 #endif
 
 static enum tap_state jlink_last_state = TAP_RESET;
 
-static jlink_jtag_t* jlink_jtag_handle;
+static struct jlink* jlink_handle;
 
 /***************************************************************************/
 /* External interface implementation */
 
-jtag_interface_t jlink_interface =
+struct jtag_interface jlink_interface =
 {
 	.name = "jlink",
 	.execute_queue = jlink_execute_queue,
@@ -139,38 +146,26 @@ jtag_interface_t jlink_interface =
 	.quit = jlink_quit
 };
 
-static void jlink_execute_end_state(jtag_command_t *cmd)
-{
-	DEBUG_JTAG_IO("end_state: %i", cmd->cmd.end_state->end_state);
-
-	if (cmd->cmd.end_state->end_state != TAP_INVALID)
-		jlink_end_state(cmd->cmd.end_state->end_state);
-}
-
-static void jlink_execute_runtest(jtag_command_t *cmd)
+static void jlink_execute_runtest(struct jtag_command *cmd)
 {
 	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 != TAP_INVALID)
-		jlink_end_state(cmd->cmd.runtest->end_state);
+	jlink_end_state(cmd->cmd.runtest->end_state);
 
 	jlink_runtest(cmd->cmd.runtest->num_cycles);
 }
 
-static void jlink_execute_statemove(jtag_command_t *cmd)
+static void jlink_execute_statemove(struct jtag_command *cmd)
 {
 	DEBUG_JTAG_IO("statemove end in %i", cmd->cmd.statemove->end_state);
 
-	if (cmd->cmd.statemove->end_state != TAP_INVALID)
-	{
-		jlink_end_state(cmd->cmd.statemove->end_state);
-	}
+	jlink_end_state(cmd->cmd.statemove->end_state);
 	jlink_state_move();
 }
 
-static void jlink_execute_pathmove(jtag_command_t *cmd)
+static void jlink_execute_pathmove(struct jtag_command *cmd)
 {
 	DEBUG_JTAG_IO("pathmove: %i states, end in %i",
 		cmd->cmd.pathmove->num_states,
@@ -180,16 +175,15 @@ static void jlink_execute_pathmove(jtag_command_t *cmd)
 			cmd->cmd.pathmove->path);
 }
 
-static void jlink_execute_scan(jtag_command_t *cmd)
+static void jlink_execute_scan(struct jtag_command *cmd)
 {
 	int scan_size;
 	enum scan_type type;
-	u8 *buffer;
+	uint8_t *buffer;
 
 	DEBUG_JTAG_IO("scan end in %s", tap_state_name(cmd->cmd.scan->end_state));
 
-	if (cmd->cmd.scan->end_state != TAP_INVALID)
-		jlink_end_state(cmd->cmd.scan->end_state);
+	jlink_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);
@@ -202,34 +196,27 @@ static void jlink_execute_scan(jtag_command_t *cmd)
 			type, buffer, scan_size, cmd->cmd.scan);
 }
 
-static void jlink_execute_reset(jtag_command_t *cmd)
+static void jlink_execute_reset(struct jtag_command *cmd)
 {
 	DEBUG_JTAG_IO("reset trst: %i srst %i",
 			cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 
 	jlink_tap_execute();
-
-	if ( (cmd->cmd.reset->trst == 1) || ( cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST) ) )
-	{
-		tap_set_state(TAP_RESET);
-	}
-
 	jlink_reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 	jlink_tap_execute();
 }
 
-static void jlink_execute_sleep(jtag_command_t *cmd)
+static void jlink_execute_sleep(struct jtag_command *cmd)
 {
 	DEBUG_JTAG_IO("sleep %i", cmd->cmd.sleep->us);
 	jlink_tap_execute();
 	jtag_sleep(cmd->cmd.sleep->us);
 }
 
-static void jlink_execute_command(jtag_command_t *cmd)
+static void jlink_execute_command(struct jtag_command *cmd)
 {
 	switch (cmd->type)
 	{
-	case JTAG_END_STATE: jlink_execute_end_state(cmd); break;
 	case JTAG_RUNTEST:   jlink_execute_runtest(cmd); break;
 	case JTAG_STATEMOVE: jlink_execute_statemove(cmd); break;
 	case JTAG_PATHMOVE:  jlink_execute_pathmove(cmd); break;
@@ -244,7 +231,7 @@ static void jlink_execute_command(jtag_command_t *cmd)
 
 static int jlink_execute_queue(void)
 {
-	jtag_command_t *cmd = jtag_command_queue;
+	struct jtag_command *cmd = jtag_command_queue;
 
 	while (cmd != NULL)
 	{
@@ -275,7 +262,7 @@ static int jlink_speed(int speed)
 	usb_out_buffer[1] = (speed >> 0) & 0xff;
 	usb_out_buffer[2] = (speed >> 8) & 0xff;
 
-	result = jlink_usb_write(jlink_jtag_handle, 3);
+	result = jlink_usb_write(jlink_handle, 3);
 	if (result != 3)
 	{
 		LOG_ERROR("J-Link setting speed failed (%d)", result);
@@ -299,41 +286,39 @@ static int jlink_khz(int khz, int *jtag_speed)
 	return ERROR_OK;
 }
 
-static int jlink_register_commands(struct command_context_s *cmd_ctx)
-{
-	register_command(cmd_ctx, NULL, "jlink_info", jlink_handle_jlink_info_command, COMMAND_EXEC,
-		"query jlink info");
-	return ERROR_OK;
-}
-
 static int jlink_init(void)
 {
-	int check_cnt;
+	int i;
 
-	jlink_jtag_handle = jlink_usb_open();
+	jlink_handle = jlink_usb_open();
 
-	if (jlink_jtag_handle == 0)
+	if (jlink_handle == 0)
 	{
 		LOG_ERROR("Cannot find jlink Interface! Please check connection and permissions.");
 		return ERROR_JTAG_INIT_FAILED;
 	}
 
-	check_cnt = 0;
-	while (check_cnt < 3)
-	{
-		if (jlink_get_version_info() == ERROR_OK)
-		{
-			/* attempt to get status */
-			jlink_get_status();
-			break;
-		}
+	/*
+	 *  The next three instructions were added after discovering a problem while using an oscilloscope.  For the V8
+	 *	SAM-ICE dongle (and likely other j-link device variants), the reset line to the target microprocessor was found to
+	 *	cycle only intermittently during emulator startup (even after encountering the downstream reset instruction later
+	 *	in the code).  This was found to create two issues:  1) In general it is a bad practice to not reset a CPU to a known
+	 *	state when starting an emulator and 2) something critical happens inside the dongle when it does the first read
+	 *	following a new USB session.  Keeping the processor in reset during the first read collecting version information
+	 *	seems to prevent errant "J-Link command EMU_CMD_VERSION failed" issues.
+	 */
 
-		check_cnt++;
-	}
+	LOG_INFO("J-Link initialization started / target CPU reset initiated");
+	jlink_simple_command(EMU_CMD_HW_TRST0);
+	jlink_simple_command(EMU_CMD_HW_RESET0);
+	usleep(1000);
+
+	jlink_hw_jtag_version = 2;
 
-	if (check_cnt == 3)
+	if (jlink_get_version_info() == ERROR_OK)
 	{
-		LOG_INFO("J-Link initial read failed, don't worry");
+		/* attempt to get status */
+		jlink_get_status();
 	}
 
 	LOG_INFO("J-Link JTAG Interface ready");
@@ -341,14 +326,21 @@ static int jlink_init(void)
 	jlink_reset(0, 0);
 	jtag_sleep(3000);
 	jlink_tap_init();
-	jlink_speed(jtag_speed);
+	jlink_speed(jtag_get_speed());
+
+	/* v5/6 jlink seems to have an issue if the first tap move
+	 * is not divisible by 8, so we send a TLR on first power up */
+	for (i = 0; i < 8; i++) {
+		jlink_tap_append_step(1, 0);
+	}
+	jlink_tap_execute();
 
 	return ERROR_OK;
 }
 
 static int jlink_quit(void)
 {
-	jlink_usb_close(jlink_jtag_handle);
+	jlink_usb_close(jlink_handle);
 	return ERROR_OK;
 }
 
@@ -373,8 +365,8 @@ static void jlink_state_move(void)
 {
 	int i;
 	int tms = 0;
-	u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
-	u8 tms_scan_bits = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
+	uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
+	uint8_t tms_scan_bits = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
 
 	for (i = 0; i < tms_scan_bits; i++)
 	{
@@ -441,7 +433,7 @@ static void jlink_runtest(int num_cycles)
 	}
 }
 
-static void jlink_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size, scan_command_t *command)
+static void jlink_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size, struct scan_command *command)
 {
 	tap_state_t saved_end_state;
 
@@ -490,23 +482,21 @@ static void jlink_reset(int trst, int srst)
 	{
 		jlink_simple_command(EMU_CMD_HW_TRST0);
 	}
+
 	if (trst == 0)
 	{
 		jlink_simple_command(EMU_CMD_HW_TRST1);
-		jtag_sleep(5000);
-		jlink_end_state(TAP_RESET);
-		jlink_state_move();
 	}
 }
 
-static void jlink_simple_command(u8 command)
+static void jlink_simple_command(uint8_t command)
 {
 	int result;
 
 	DEBUG_JTAG_IO("0x%02x", command);
 
 	usb_out_buffer[0] = command;
-	result = jlink_usb_write(jlink_jtag_handle, 1);
+	result = jlink_usb_write(jlink_handle, 1);
 
 	if (result != 1)
 	{
@@ -520,7 +510,7 @@ static int jlink_get_status(void)
 
 	jlink_simple_command(EMU_CMD_GET_STATE);
 
-	result = jlink_usb_read(jlink_jtag_handle, 8);
+	result = jlink_usb_read(jlink_handle, 8);
 	if (result != 8)
 	{
 		LOG_ERROR("J-Link command EMU_CMD_GET_STATE failed (%d)\n", result);
@@ -543,12 +533,12 @@ static int jlink_get_version_info(void)
 {
 	int result;
 	int len;
-	u32 jlink_caps, jlink_max_size;
+	uint32_t jlink_caps, jlink_max_size;
 
 	/* query hardware version */
 	jlink_simple_command(EMU_CMD_VERSION);
 
-	result = jlink_usb_read(jlink_jtag_handle, 2);
+	result = jlink_usb_read(jlink_handle, 2);
 	if (2 != result)
 	{
 		LOG_ERROR("J-Link command EMU_CMD_VERSION failed (%d)\n", result);
@@ -556,7 +546,13 @@ static int jlink_get_version_info(void)
 	}
 
 	len = buf_get_u32(usb_in_buffer, 0, 16);
-	result = jlink_usb_read(jlink_jtag_handle, len);
+	if (len > JLINK_IN_BUFFER_SIZE)
+	{
+		LOG_ERROR("J-Link command EMU_CMD_VERSION impossible return length 0x%0x", len);
+		len = JLINK_IN_BUFFER_SIZE;
+	}
+
+	result = jlink_usb_read(jlink_handle, len);
 	if (result != len)
 	{
 		LOG_ERROR("J-Link command EMU_CMD_VERSION failed (%d)\n", result);
@@ -569,7 +565,7 @@ static int jlink_get_version_info(void)
 	/* query hardware capabilities */
 	jlink_simple_command(EMU_CMD_GET_CAPS);
 
-	result = jlink_usb_read(jlink_jtag_handle, 4);
+	result = jlink_usb_read(jlink_handle, 4);
 	if (4 != result)
 	{
 		LOG_ERROR("J-Link command EMU_CMD_GET_CAPS failed (%d)\n", result);
@@ -577,27 +573,48 @@ static int jlink_get_version_info(void)
 	}
 
 	jlink_caps = buf_get_u32(usb_in_buffer, 0, 32);
-	LOG_INFO("JLink caps 0x%x", jlink_caps);
+	LOG_INFO("JLink caps 0x%x", (unsigned)jlink_caps);
 
+	if (jlink_caps & (1 << EMU_CAP_GET_HW_VERSION))
+	{
+		/* query hardware version */
+		jlink_simple_command(EMU_CMD_GET_HW_VERSION);
 
-	/* query hardware maximum memory block */
-	jlink_simple_command(EMU_CMD_GET_MAX_MEM_BLOCK);
+		result = jlink_usb_read(jlink_handle, 4);
+		if (4 != result)
+		{
+			LOG_ERROR("J-Link command EMU_CMD_GET_HW_VERSION failed (%d)\n", result);
+			return ERROR_JTAG_DEVICE_ERROR;
+		}
 
-	result = jlink_usb_read(jlink_jtag_handle, 4);
-	if (4 != result)
-	{
-		LOG_ERROR("J-Link command EMU_CMD_GET_MAX_MEM_BLOCK failed (%d)\n", result);
-		return ERROR_JTAG_DEVICE_ERROR;
+		uint32_t jlink_hw_version = buf_get_u32(usb_in_buffer, 0, 32);
+		uint32_t major_revision = (jlink_hw_version / 10000) % 100;
+		if (major_revision >= 5)
+			jlink_hw_jtag_version = 3;
+
+		LOG_INFO("JLink hw version %i", (int)jlink_hw_version);
 	}
 
-	jlink_max_size = buf_get_u32(usb_in_buffer, 0, 32);
-	LOG_INFO("JLink max mem block %i", jlink_max_size);
+	if (jlink_caps & (1 << EMU_CAP_GET_MAX_BLOCK_SIZE))
+	{
+		/* query hardware maximum memory block */
+		jlink_simple_command(EMU_CMD_GET_MAX_MEM_BLOCK);
 
+		result = jlink_usb_read(jlink_handle, 4);
+		if (4 != result)
+		{
+			LOG_ERROR("J-Link command EMU_CMD_GET_MAX_MEM_BLOCK failed (%d)\n", result);
+			return ERROR_JTAG_DEVICE_ERROR;
+		}
+
+		jlink_max_size = buf_get_u32(usb_in_buffer, 0, 32);
+		LOG_INFO("JLink max mem block %i", (int)jlink_max_size);
+	}
 
 	return ERROR_OK;
 }
 
-static int jlink_handle_jlink_info_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
+COMMAND_HANDLER(jlink_handle_jlink_info_command)
 {
 	if (jlink_get_version_info() == ERROR_OK)
 	{
@@ -608,27 +625,62 @@ static int jlink_handle_jlink_info_command(struct command_context_s *cmd_ctx, ch
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(jlink_handle_jlink_hw_jtag_command)
+{
+	switch (argc) {
+	case 0:
+		command_print(cmd_ctx, "jlink hw jtag  %i", jlink_hw_jtag_version);
+		break;
+	case 1: {
+		int request_version = atoi(args[0]);
+		switch (request_version) {
+		case 2: case 3:
+			jlink_hw_jtag_version = request_version;
+			break;
+		default:
+			return ERROR_COMMAND_SYNTAX_ERROR;
+		}
+		break;
+	}
+	default:
+		return ERROR_COMMAND_SYNTAX_ERROR;
+	}
+
+	return ERROR_OK;
+}
+
+static int jlink_register_commands(struct command_context *cmd_ctx)
+{
+
+	register_command(cmd_ctx, NULL, "jlink_info",
+		&jlink_handle_jlink_info_command, COMMAND_EXEC,
+		"query jlink info");
+	register_command(cmd_ctx, NULL, "jlink_hw_jtag",
+		&jlink_handle_jlink_hw_jtag_command, COMMAND_EXEC,
+		"set/get jlink hw jtag command version [2 | 3]");
+	return ERROR_OK;
+}
+
 /***************************************************************************/
 /* J-Link tap functions */
 
 
-static unsigned tap_length=0;
-static u8 tms_buffer[JLINK_TAP_BUFFER_SIZE];
-static u8 tdi_buffer[JLINK_TAP_BUFFER_SIZE];
-static u8 tdo_buffer[JLINK_TAP_BUFFER_SIZE];
+static unsigned tap_length = 0;
+static uint8_t tms_buffer[JLINK_TAP_BUFFER_SIZE];
+static uint8_t tdi_buffer[JLINK_TAP_BUFFER_SIZE];
+static uint8_t tdo_buffer[JLINK_TAP_BUFFER_SIZE];
 
-typedef struct
-{
+struct pending_scan_result {
 	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;
+	struct scan_command *command; /* Corresponding scan command */
+	uint8_t *buffer;
+};
 
 #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 struct pending_scan_result pending_scan_results_buffer[MAX_PENDING_SCAN_RESULTS];
 
 static void jlink_tap_init(void)
 {
@@ -654,12 +706,12 @@ static void jlink_tap_append_step(int tms, int tdi)
 	if (index >= JLINK_TAP_BUFFER_SIZE)
 	{
 		LOG_ERROR("jlink_tap_append_step: overflow");
-		*(u32 *)0xFFFFFFFF = 0;
+		*(uint32_t *)0xFFFFFFFF = 0;
 		exit(-1);
 	}
 
 	int bit_index = tap_length % 8;
-	u8 bit = 1 << bit_index;
+	uint8_t bit = 1 << bit_index;
 
 	// we do not pad TMS, so be sure to initialize all bits
 	if (0 == bit_index)
@@ -680,9 +732,9 @@ static void jlink_tap_append_step(int tms, int tdi)
 	tap_length++;
 }
 
-static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *command)
+static void jlink_tap_append_scan(int length, uint8_t *buffer, struct scan_command *command)
 {
-	pending_scan_result_t *pending_scan_result =
+	struct pending_scan_result *pending_scan_result =
 		&pending_scan_results_buffer[pending_scan_results_length];
 	int i;
 
@@ -694,7 +746,7 @@ static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *comman
 	for (i = 0; i < length; i++)
 	{
 		int tms = (i < (length - 1)) ? 0 : 1;
-		int tdi = (buffer[i / 8] & (1 << (i % 8)))!=0;
+		int tdi = (buffer[i / 8] & (1 << (i % 8))) != 0;
 		jlink_tap_append_step(tms, tdi);
 	}
 	pending_scan_results_length++;
@@ -711,17 +763,19 @@ static int jlink_tap_execute(void)
 	if (!tap_length)
 		return ERROR_OK;
 
-	/* JLink returns an extra NULL in packet when size of in message is a multiple of 64, creates problems with usb comms */
-	/* WARNING This will interfere with tap state counting */
-	while ((TAP_SCAN_BYTES(tap_length)%64)==0)
+	/* JLink returns an extra NULL in packet when size of incoming
+	 * message is a multiple of 64, creates problems with USB comms.
+	 * WARNING: This will interfere with tap state counting. */
+	while ((DIV_ROUND_UP(tap_length, 8) % 64) == 0)
 	{
 		jlink_tap_append_step((tap_get_state() == TAP_RESET)?1:0, 0);
 	}
 
 	// number of full bytes (plus one if some would be left over)
-	byte_length = TAP_SCAN_BYTES(tap_length);
+	byte_length = DIV_ROUND_UP(tap_length, 8);
 
-	usb_out_buffer[0] = EMU_CMD_HW_JTAG3;
+	bool use_jtag3 = jlink_hw_jtag_version >= 3;
+	usb_out_buffer[0] = use_jtag3 ? EMU_CMD_HW_JTAG3 : EMU_CMD_HW_JTAG2;
 	usb_out_buffer[1] = 0;
 	usb_out_buffer[2] = (tap_length >> 0) & 0xff;
 	usb_out_buffer[3] = (tap_length >> 8) & 0xff;
@@ -731,7 +785,7 @@ static int jlink_tap_execute(void)
 	jlink_last_state = jtag_debug_state_machine(tms_buffer, tdi_buffer,
 			tap_length, jlink_last_state);
 
-	result = jlink_usb_message(jlink_jtag_handle, 4 + 2 * byte_length, byte_length);
+	result = jlink_usb_message(jlink_handle, 4 + 2 * byte_length, byte_length);
 	if (result != byte_length)
 	{
 		LOG_ERROR("jlink_tap_execute, wrong result %d (expected %d)", result, byte_length);
@@ -743,11 +797,11 @@ static int jlink_tap_execute(void)
 
 	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;
+		struct pending_scan_result *pending_scan_result = &pending_scan_results_buffer[i];
+		uint8_t *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;
+		struct scan_command *command = pending_scan_result->command;
 
 		/* Copy to buffer */
 		buf_set_buf(tdo_buffer, first, buffer, 0, length);
@@ -755,7 +809,7 @@ static int jlink_tap_execute(void)
 		DEBUG_JTAG_IO("pending scan result, length = %d", length);
 
 #ifdef _DEBUG_USB_COMMS_
-		jlink_debug_buffer(buffer, byte_length);
+		jlink_debug_buffer(buffer, DIV_ROUND_UP(length, 8));
 #endif
 
 		if (jtag_read_buffer(buffer, command) != ERROR_OK)
@@ -774,48 +828,119 @@ static int jlink_tap_execute(void)
 	return ERROR_OK;
 }
 
-/*****************************************************************************/
-/* JLink USB low-level functions */
-
-static jlink_jtag_t* jlink_usb_open()
+static struct usb_device* find_jlink_device(void)
 {
 	struct usb_bus *busses;
 	struct usb_bus *bus;
 	struct usb_device *dev;
 
-	jlink_jtag_t *result;
-
-	result = (jlink_jtag_t*) malloc(sizeof(jlink_jtag_t));
-
-	usb_init();
 	usb_find_busses();
 	usb_find_devices();
 
 	busses = usb_get_busses();
 
-	/* find jlink_jtag device in usb bus */
+	/* find jlink device in usb bus */
 
 	for (bus = busses; bus; bus = bus->next)
 	{
 		for (dev = bus->devices; dev; dev = dev->next)
 		{
-			if ((dev->descriptor.idVendor == VID) && (dev->descriptor.idProduct == PID))
-			{
-				result->usb_handle = usb_open(dev);
+			if ((dev->descriptor.idVendor == VID) && (dev->descriptor.idProduct == PID)) {
+				return dev;
+			}
+		}
+	}
+
+	return NULL;
+}
+
+/*****************************************************************************/
+/* JLink USB low-level functions */
+
+static struct jlink* jlink_usb_open()
+{
+	struct usb_device *dev;
+
+	struct jlink *result;
 
-				/* usb_set_configuration required under win32 */
-				usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
-				usb_claim_interface(result->usb_handle, 0);
+	result = (struct jlink*) malloc(sizeof(struct jlink));
+
+	usb_init();
+
+	if ((dev = find_jlink_device()) == NULL) {
+		free(result);
+		return NULL;
+	}
+
+	result->usb_handle = usb_open(dev);
+
+	if (result->usb_handle)
+	{
+
+		/* BE ***VERY CAREFUL*** ABOUT MAKING CHANGES IN THIS AREA!!!!!!!!!!!
+		 * The behavior of libusb is not completely consistent across Windows, Linux, and Mac OS X platforms.  The actions taken
+		 * in the following compiler conditionals may not agree with published documentation for libusb, but were found
+		 * to be necessary through trials and tribulations.  Even little tweaks can break one or more platforms, so if you do make changes
+		 * test them carefully on all platforms before committing them!
+		 */
+
+#if IS_WIN32 == 0
+
+		usb_reset(result->usb_handle);
+
+#if IS_DARWIN == 0
+
+		int timeout = 5;
+
+		/* reopen jlink after usb_reset
+		 * on win32 this may take a second or two to re-enumerate */
+		while ((dev = find_jlink_device()) == NULL)
+		{
+			usleep(1000);
+			timeout--;
+			if (!timeout) {
+				break;
+			}
+		}
+
+		if (dev == NULL)
+		{
+			free(result);
+			return NULL;
+		}
+
+		result->usb_handle = usb_open(dev);
+#endif
+
+#endif
+
+		if (result->usb_handle)
+		{
+			/* usb_set_configuration required under win32 */
+			usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
+			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);
+			/*
+			 * 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;
+			struct usb_interface *iface = dev->config->interface;
+			struct usb_interface_descriptor *desc = iface->altsetting;
+			for (int i = 0; i < desc->bNumEndpoints; i++)
+			{
+				uint8_t epnum = desc->endpoint[i].bEndpointAddress;
+				bool is_input = epnum & 0x80;
+				LOG_DEBUG("usb ep %s %02x", is_input ? "in" : "out", epnum);
+				if (is_input)
+					jlink_read_ep = epnum;
+				else
+					jlink_write_ep = epnum;
 			}
+
+			return result;
 		}
 	}
 
@@ -823,19 +948,18 @@ static jlink_jtag_t* jlink_usb_open()
 	return NULL;
 }
 
-static void jlink_usb_close(jlink_jtag_t *jlink_jtag)
+static void jlink_usb_close(struct jlink *jlink)
 {
-	usb_close(jlink_jtag->usb_handle);
-	free(jlink_jtag);
+	usb_close(jlink->usb_handle);
+	free(jlink);
 }
 
 /* Send a message and receive the reply. */
-static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_length)
+static int jlink_usb_message(struct jlink *jlink, int out_length, int in_length)
 {
 	int result;
-	int result2;
 
-	result = jlink_usb_write(jlink_jtag, out_length);
+	result = jlink_usb_write(jlink, out_length);
 	if (result != out_length)
 	{
 		LOG_ERROR("usb_bulk_write failed (requested=%d, result=%d)",
@@ -843,7 +967,7 @@ static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_le
 		return ERROR_JTAG_DEVICE_ERROR;
 	}
 
-	result = jlink_usb_read(jlink_jtag, in_length);
+	result = jlink_usb_read(jlink, in_length);
 	if ((result != in_length) && (result != (in_length + 1)))
 	{
 		LOG_ERROR("usb_bulk_read failed (requested=%d, result=%d)",
@@ -851,19 +975,23 @@ static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_le
 		return ERROR_JTAG_DEVICE_ERROR;
 	}
 
+	if (jlink_hw_jtag_version < 3)
+		return result;
+
+	int result2 = ERROR_OK;
 	if (result == in_length)
 	{
 		/* Must read the result from the EMU too */
-		result2 = jlink_usb_read_emu_result(jlink_jtag);
+		result2 = jlink_usb_read_emu_result(jlink);
 		if (1 != result2)
 		{
-			LOG_ERROR("jlink_usb_read_emu_result retried requested=1, result=%d, in_length=%i", result2,in_length);
-			/* Try again once, should only happen if (in_length%64==0) */
-			result2 = jlink_usb_read_emu_result(jlink_jtag);
+			LOG_ERROR("jlink_usb_read_emu_result retried requested = 1, result=%d, in_length=%i", result2,in_length);
+			/* Try again once, should only happen if (in_length%64 == 0) */
+			result2 = jlink_usb_read_emu_result(jlink);
 			if (1 != result2)
 			{
 				LOG_ERROR("jlink_usb_read_emu_result failed "
-					"(requested=1, result=%d)", result2);
+					"(requested = 1, result=%d)", result2);
 				return ERROR_JTAG_DEVICE_ERROR;
 			}
 		}
@@ -927,17 +1055,17 @@ static inline int usb_bulk_read_ex(usb_dev_handle *dev, int ep,
 }
 
 /* Write data from out_buffer to USB. */
-static int jlink_usb_write(jlink_jtag_t *jlink_jtag, int out_length)
+static int jlink_usb_write(struct jlink *jlink, int out_length)
 {
 	int result;
 
 	if (out_length > JLINK_OUT_BUFFER_SIZE)
 	{
-		LOG_ERROR("jlink_jtag_write illegal out_length=%d (max=%d)", out_length, JLINK_OUT_BUFFER_SIZE);
+		LOG_ERROR("jlink_write illegal out_length=%d (max=%d)", out_length, JLINK_OUT_BUFFER_SIZE);
 		return -1;
 	}
 
-	result = usb_bulk_write_ex(jlink_jtag->usb_handle, JLINK_WRITE_ENDPOINT,
+	result = usb_bulk_write_ex(jlink->usb_handle, jlink_write_ep,
 		(char *)usb_out_buffer, out_length, JLINK_USB_TIMEOUT);
 
 	DEBUG_JTAG_IO("jlink_usb_write, out_length = %d, result = %d", out_length, result);
@@ -949,9 +1077,9 @@ static int jlink_usb_write(jlink_jtag_t *jlink_jtag, int out_length)
 }
 
 /* Read data from USB into in_buffer. */
-static int jlink_usb_read(jlink_jtag_t *jlink_jtag, int expected_size)
+static int jlink_usb_read(struct jlink *jlink, int expected_size)
 {
-	int result = usb_bulk_read_ex(jlink_jtag->usb_handle, JLINK_READ_ENDPOINT,
+	int result = usb_bulk_read_ex(jlink->usb_handle, jlink_read_ep,
 		(char *)usb_in_buffer, expected_size, JLINK_USB_TIMEOUT);
 
 	DEBUG_JTAG_IO("jlink_usb_read, result = %d", result);
@@ -963,9 +1091,9 @@ static int jlink_usb_read(jlink_jtag_t *jlink_jtag, int expected_size)
 }
 
 /* Read the result from the previous EMU cmd into result_buffer. */
-static int jlink_usb_read_emu_result(jlink_jtag_t *jlink_jtag)
+static int jlink_usb_read_emu_result(struct jlink *jlink)
 {
-	int result = usb_bulk_read_ex(jlink_jtag->usb_handle, JLINK_READ_ENDPOINT,
+	int result = usb_bulk_read_ex(jlink->usb_handle, jlink_read_ep,
 		(char *)usb_emu_result_buffer, 1 /* JLINK_EMU_RESULT_BUFFER_SIZE */,
 		JLINK_USB_TIMEOUT);
 
@@ -980,7 +1108,7 @@ static int jlink_usb_read_emu_result(jlink_jtag_t *jlink_jtag)
 #ifdef _DEBUG_USB_COMMS_
 #define BYTES_PER_LINE  16
 
-static void jlink_debug_buffer(u8 *buffer, int length)
+static void jlink_debug_buffer(uint8_t *buffer, int length)
 {
 	char line[81];
 	char s[4];