presto.c

/***************************************************************************
 *   Copyright (C) 2007 by Pavel Chromy                                    *
 *   chromy@asix.cz                                                        *
 *                                                                         *
 *   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

#if IS_CYGWIN == 1
#include "windows.h"
#endif

#include "interface.h"
#include "time_support.h"
#include "bitq.h"


/* PRESTO access library includes */
#if BUILD_PRESTO_FTD2XX == 1
#include <ftd2xx.h>
#elif BUILD_PRESTO_LIBFTDI == 1
#include <ftdi.h>
#else
#error "BUG: either FTD2XX and LIBFTDI has to be used"
#endif

static int presto_jtag_speed(int speed);
static int presto_jtag_khz(int khz, int *jtag_speed);
static int presto_jtag_speed_div(int speed, int *khz);
static int presto_jtag_register_commands(struct command_context_s *cmd_ctx);
static int presto_jtag_init(void);
static int presto_jtag_quit(void);

jtag_interface_t presto_interface =
{
	.name = "presto",
	.execute_queue = bitq_execute_queue,
	.speed = presto_jtag_speed,
	.khz = presto_jtag_khz,
	.speed_div = presto_jtag_speed_div,
	.register_commands = presto_jtag_register_commands,
	.init = presto_jtag_init,
	.quit = presto_jtag_quit,
};

static int presto_bitq_out(int tms, int tdi, int tdo_req);
static int presto_bitq_flush(void);
static int presto_bitq_sleep(unsigned long us);
static int presto_bitq_reset(int trst, int srst);
static int presto_bitq_in_rdy(void);
static int presto_bitq_in(void);

static bitq_interface_t presto_bitq =
{
	.out = presto_bitq_out,
	.flush = presto_bitq_flush,
	.sleep = presto_bitq_sleep,
	.reset = presto_bitq_reset,
	.in_rdy = presto_bitq_in_rdy,
	.in = presto_bitq_in,
};

/* -------------------------------------------------------------------------- */

#define FT_DEVICE_NAME_LEN 64
#define FT_DEVICE_SERNUM_LEN 64

#define PRESTO_VID_PID 0x0403f1a0
#define PRESTO_VID (0x0403)
#define PRESTO_PID (0xf1a0)

#define BUFFER_SIZE (64*62)

typedef struct presto_s
{
#if BUILD_PRESTO_FTD2XX == 1
	FT_HANDLE handle;
	FT_STATUS status;
#elif BUILD_PRESTO_LIBFTDI == 1
	struct ftdi_context ftdic;
	int retval;
#endif

	char serial[FT_DEVICE_SERNUM_LEN];

	uint8_t buff_out[BUFFER_SIZE];
	int buff_out_pos;

	uint8_t buff_in[BUFFER_SIZE];
	int buff_in_exp; /* expected in buffer length */
	int buff_in_len; /* length of data received */
	int buff_in_pos;

	unsigned long total_out;
	unsigned long total_in;

	int jtag_tms; /* last tms state */
	int jtag_tck; /* last tck state */
	int jtag_rst; /* last trst state */

	int jtag_tdi_data;
	int jtag_tdi_count;

	int jtag_speed;

} presto_t;

static presto_t presto_state;
static presto_t *presto = &presto_state;

static uint8_t presto_init_seq[] =
{
	0x80, 0xA0, 0xA8, 0xB0, 0xC0, 0xE0
};

static int presto_write(uint8_t *buf, uint32_t size)
{
#if BUILD_PRESTO_FTD2XX == 1
	DWORD ftbytes;
	if ((presto->status = FT_Write(presto->handle, buf, size, &ftbytes)) != FT_OK)
	{
		LOG_ERROR("FT_Write returned: %lu", presto->status);
		return ERROR_JTAG_DEVICE_ERROR;
	}

#elif BUILD_PRESTO_LIBFTDI == 1
	uint32_t ftbytes;
	if ((presto->retval = ftdi_write_data(&presto->ftdic, buf, size)) < 0)
	{
		LOG_ERROR("ftdi_write_data: %s", ftdi_get_error_string(&presto->ftdic));
		return ERROR_JTAG_DEVICE_ERROR;
	}
	ftbytes = presto->retval;
#endif

	if (ftbytes != size)
	{
		LOG_ERROR("couldn't write the requested number of bytes to PRESTO (%u < %u)", 
			  (unsigned)ftbytes, (unsigned)size);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	return ERROR_OK;
}

static int presto_read(uint8_t* buf, uint32_t size)
{
#if BUILD_PRESTO_FTD2XX == 1
	DWORD ftbytes;
	if ((presto->status = FT_Read(presto->handle, buf, size, &ftbytes)) != FT_OK)
	{
		LOG_ERROR("FT_Read returned: %lu", presto->status);
		return ERROR_JTAG_DEVICE_ERROR;
	}

#elif BUILD_PRESTO_LIBFTDI == 1
	uint32_t ftbytes = 0;

	struct timeval timeout, now;
	gettimeofday(&timeout, NULL);
	timeval_add_time(&timeout, 1, 0); /* one second timeout */

	while (ftbytes < size)
	{
		if ((presto->retval = ftdi_read_data(&presto->ftdic, buf + ftbytes, size - ftbytes)) < 0)
		{
			LOG_ERROR("ftdi_read_data: %s", ftdi_get_error_string(&presto->ftdic));
			return ERROR_JTAG_DEVICE_ERROR;
		}
		ftbytes += presto->retval;

		gettimeofday(&now, NULL);
		if ((now.tv_sec > timeout.tv_sec) || ((now.tv_sec == timeout.tv_sec) && (now.tv_usec > timeout.tv_usec)))
			break;
	}
#endif

	if (ftbytes != size)
	{
		/* this is just a warning, there might have been timeout when detecting PRESTO, which is not fatal */
		LOG_WARNING("couldn't read the requested number of bytes from PRESTO (%u < %u)", 
			    (unsigned)ftbytes, (unsigned)size);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	return ERROR_OK;
}

#if BUILD_PRESTO_FTD2XX == 1
static int presto_open_ftd2xx(char *req_serial)
{
	uint32_t i;
	DWORD numdevs;
	DWORD vidpid;
	char devname[FT_DEVICE_NAME_LEN];
	FT_DEVICE device;

	BYTE presto_data;
	DWORD ftbytes;

	presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;

#if IS_WIN32 == 0
	/* Add non-standard Vid/Pid to the linux driver */
	if ((presto->status = FT_SetVIDPID(PRESTO_VID, PRESTO_PID)) != FT_OK)
	{
		LOG_ERROR("couldn't add PRESTO VID/PID");
		exit(-1);
	}
#endif

	if ((presto->status = FT_ListDevices(&numdevs, NULL, FT_LIST_NUMBER_ONLY)) != FT_OK)
	{
		LOG_ERROR("FT_ListDevices failed: %i", (int)presto->status);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	LOG_DEBUG("FTDI devices available: %lu", numdevs);
	for (i = 0; i < numdevs; i++)
	{
		if ((presto->status = FT_Open(i, &(presto->handle))) != FT_OK)
		{
			/* this is not fatal, the device may be legitimately open by other process, hence debug message only */
			LOG_DEBUG("FT_Open failed: %i", (int)presto->status);
			continue;
		}
		LOG_DEBUG("FTDI device %i open", i);

		if ((presto->status = FT_GetDeviceInfo(presto->handle, &device, &vidpid,
				presto->serial, devname, NULL)) == FT_OK)
		{
			if (vidpid == PRESTO_VID_PID
					&& (req_serial == NULL || !strcmp(presto->serial, req_serial)))
				break;
		}
		else
			LOG_DEBUG("FT_GetDeviceInfo failed: %lu", presto->status);

		LOG_DEBUG("FTDI device %i does not match, closing", i);
		FT_Close(presto->handle);
		presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;
	}

	if (presto->handle == (FT_HANDLE)INVALID_HANDLE_VALUE)
		return ERROR_JTAG_DEVICE_ERROR; /* presto not open, return */

	if ((presto->status = FT_SetLatencyTimer(presto->handle, 1)) != FT_OK)
		return ERROR_JTAG_DEVICE_ERROR;


	if ((presto->status = FT_SetTimeouts(presto->handle, 100, 0)) != FT_OK)
		return ERROR_JTAG_DEVICE_ERROR;

	if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
		return ERROR_JTAG_DEVICE_ERROR;

	presto_data = 0xD0;
	if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
		return ERROR_JTAG_DEVICE_ERROR;

	/* delay between first write/read turnaround (after purge?) necessary under Linux for unknown reason,
	   probably a bug in library threading */
	usleep(100000);
	if ((presto->status = FT_Read(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
		return ERROR_JTAG_DEVICE_ERROR;

	if (ftbytes!=1)
	{
		LOG_DEBUG("PRESTO reset");

		if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;
		if ((presto->status = FT_SetBitMode(presto->handle, 0x80, 1)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;
		if ((presto->status = FT_SetBaudRate(presto->handle, 9600)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;

		presto_data = 0;
		for (i = 0; i < 4 * 62; i++)
			if ((presto->status=FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
				return ERROR_JTAG_DEVICE_ERROR;

		usleep(100000);

		if ((presto->status = FT_SetBitMode(presto->handle, 0x00, 0)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;

		if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;

		presto_data = 0xD0;
		if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;

		/* delay between first write/read turnaround (after purge?) necessary under Linux for unknown reason,
		   probably a bug in library threading */
		usleep(100000);
		if ((presto->status = FT_Read(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
			return ERROR_JTAG_DEVICE_ERROR;

		if (ftbytes!=1)
		{
			LOG_DEBUG("PRESTO not responding");
			return ERROR_JTAG_DEVICE_ERROR;
		}
	}

	if ((presto->status = FT_SetTimeouts(presto->handle, 0, 0)) != FT_OK)
		return ERROR_JTAG_DEVICE_ERROR;


	presto->status = FT_Write(presto->handle, &presto_init_seq, sizeof(presto_init_seq), &ftbytes);
	if (presto->status != FT_OK || ftbytes != sizeof(presto_init_seq))
		return ERROR_JTAG_DEVICE_ERROR;

	return ERROR_OK;
}

#elif BUILD_PRESTO_LIBFTDI == 1
static int presto_open_libftdi(char *req_serial)
{
	uint8_t presto_data;

	LOG_DEBUG("searching for PRESTO using libftdi");

	/* initialize FTDI context structure */
	if (ftdi_init(&presto->ftdic) < 0)
	{
		LOG_ERROR("unable to init libftdi: %s", presto->ftdic.error_str);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	/* context, vendor id, product id */
	if (ftdi_usb_open_desc(&presto->ftdic, PRESTO_VID, PRESTO_PID, NULL, req_serial) < 0)
	{
		LOG_ERROR("unable to open PRESTO: %s", presto->ftdic.error_str);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	if (ftdi_usb_reset(&presto->ftdic) < 0)
	{
		LOG_ERROR("unable to reset PRESTO device");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	if (ftdi_set_latency_timer(&presto->ftdic, 1) < 0)
	{
		LOG_ERROR("unable to set latency timer");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	if (ftdi_usb_purge_buffers(&presto->ftdic) < 0)
	{
		LOG_ERROR("unable to purge PRESTO buffers");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	presto_data = 0xD0;
	if (presto_write(&presto_data, 1) != ERROR_OK)
	{
		LOG_ERROR("error writing to PRESTO");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	if (presto_read(&presto_data, 1) != ERROR_OK)
	{
		LOG_DEBUG("no response from PRESTO, retrying");

		if (ftdi_usb_purge_buffers(&presto->ftdic) < 0)
			return ERROR_JTAG_DEVICE_ERROR;

		presto_data = 0xD0;
		if (presto_write(&presto_data, 1) != ERROR_OK)
			return ERROR_JTAG_DEVICE_ERROR;

		if (presto_read(&presto_data, 1) != ERROR_OK)
		{
			LOG_ERROR("no response from PRESTO, giving up");
			return ERROR_JTAG_DEVICE_ERROR;
		}
	}

	if (presto_write(presto_init_seq, sizeof(presto_init_seq)) != ERROR_OK)
	{
		LOG_ERROR("error writing PRESTO init sequence");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	return ERROR_OK;
}
#endif /* BUILD_PRESTO_LIBFTDI == 1 */

static int presto_open(char *req_serial)
{
	presto->buff_out_pos=0;
	presto->buff_in_pos=0;
	presto->buff_in_len=0;
	presto->buff_in_exp=0;

	presto->total_out=0;
	presto->total_in=0;

	presto->jtag_tms=0;
	presto->jtag_tck=0;
	presto->jtag_rst=0;
	presto->jtag_tdi_data=0;
	presto->jtag_tdi_count=0;

	presto->jtag_speed=0;

#if BUILD_PRESTO_FTD2XX == 1
	return presto_open_ftd2xx(req_serial);
#elif BUILD_PRESTO_LIBFTDI == 1
	return presto_open_libftdi(req_serial);
#endif
}

static int presto_close(void)
{

	int result = ERROR_OK;

#if BUILD_PRESTO_FTD2XX == 1
	unsigned long ftbytes;

	if (presto->handle == (FT_HANDLE)INVALID_HANDLE_VALUE)
		return result;

	presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX);
	if (presto->status != FT_OK)
		result = ERROR_JTAG_DEVICE_ERROR;

	presto->status = FT_Write(presto->handle, &presto_init_seq, sizeof(presto_init_seq), &ftbytes);
	if (presto->status != FT_OK || ftbytes != sizeof(presto_init_seq))
		result = ERROR_JTAG_DEVICE_ERROR;

	if ((presto->status = FT_SetLatencyTimer(presto->handle, 16)) != FT_OK)
		result = ERROR_JTAG_DEVICE_ERROR;

	if ((presto->status = FT_Close(presto->handle)) != FT_OK)
		result = ERROR_JTAG_DEVICE_ERROR;
	else
		presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;

#elif BUILD_PRESTO_LIBFTDI == 1

	if ((presto->retval = ftdi_write_data(&presto->ftdic, presto_init_seq, sizeof(presto_init_seq))) != sizeof(presto_init_seq))
		result = ERROR_JTAG_DEVICE_ERROR;

	if ((presto->retval = ftdi_set_latency_timer(&presto->ftdic, 16)) < 0)
		result = ERROR_JTAG_DEVICE_ERROR;

	if ((presto->retval = ftdi_usb_close(&presto->ftdic)) < 0)
		result = ERROR_JTAG_DEVICE_ERROR;
	else
		ftdi_deinit(&presto->ftdic);
#endif

	return result;
}

static int presto_flush(void)
{
	if (presto->buff_out_pos == 0)
		return ERROR_OK;

#if BUILD_PRESTO_FTD2XX == 1
	if (presto->status != FT_OK)
#elif BUILD_PRESTO_LIBFTDI == 1
	if (presto->retval < 0)
#endif
	{
		LOG_DEBUG("error in previous communication, canceling I/O operation");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	if (presto_write(presto->buff_out, presto->buff_out_pos) != ERROR_OK)
	{
		presto->buff_out_pos = 0;
		return ERROR_JTAG_DEVICE_ERROR;
	}

	presto->total_out += presto->buff_out_pos;
	presto->buff_out_pos = 0;

	if (presto->buff_in_exp == 0)
		return ERROR_OK;

	presto->buff_in_pos = 0;
	presto->buff_in_len = 0;

	if (presto_read(presto->buff_in, presto->buff_in_exp) != ERROR_OK)
	{
		presto->buff_in_exp = 0;
		return ERROR_JTAG_DEVICE_ERROR;
	}

	presto->total_in += presto->buff_in_exp;
	presto->buff_in_len = presto->buff_in_exp;
	presto->buff_in_exp = 0;

	return ERROR_OK;
}

static int presto_sendbyte(int data)
{
	if (data == EOF) return presto_flush();

	if (presto->buff_out_pos < BUFFER_SIZE)
	{
		presto->buff_out[presto->buff_out_pos++] = (uint8_t)data;
		if (((data & 0xC0) == 0x40) || ((data & 0xD0)== 0xD0))
			presto->buff_in_exp++;
	}
	else
		return ERROR_JTAG_DEVICE_ERROR;

#if BUILD_PRESTO_FTD2XX == 1
	if (presto->buff_out_pos >= BUFFER_SIZE)
#elif BUILD_PRESTO_LIBFTDI == 1
	/* libftdi does not do background read, be sure that USB IN buffer does not overflow (128 bytes only!) */
	if (presto->buff_out_pos >= BUFFER_SIZE || presto->buff_in_exp==128)
#endif
		return presto_flush();

	return ERROR_OK;
}

#if 0
static int presto_getbyte(void)
{
	if (presto->buff_in_pos < presto->buff_in_len)
		return presto->buff_in[presto->buff_in_pos++];

	if (presto->buff_in_exp == 0)
		return -1;

	if (presto_flush() != ERROR_OK)
		return -1;

	if (presto->buff_in_pos<presto->buff_in_len)
		return presto->buff_in[presto->buff_in_pos++];

	return -1;
}
#endif

/* -------------------------------------------------------------------------- */

static int presto_tdi_flush(void)
{
	if (presto->jtag_tdi_count == 0)
		return 0;

	if (presto->jtag_tck == 0)
	{
		LOG_ERROR("BUG: unexpected TAP condition, TCK low");
		return -1;
	}

	presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
	presto_sendbyte(presto->jtag_tdi_data);
	presto->jtag_tdi_count = 0;
	presto->jtag_tdi_data = 0;

	return 0;
}

static int presto_tck_idle(void)
{
	if (presto->jtag_tck == 1)
	{
		presto_sendbyte(0xCA);
		presto->jtag_tck = 0;
	}

	return 0;
}

/* -------------------------------------------------------------------------- */

static int presto_bitq_out(int tms, int tdi, int tdo_req)
{
	int i;
	unsigned char cmd;

	if (presto->jtag_tck == 0)
	{
		presto_sendbyte(0xA4); /* LED idicator - JTAG active */
	}
	else if (presto->jtag_speed == 0 && !tdo_req && tms == presto->jtag_tms)
	{
		presto->jtag_tdi_data |= (tdi != 0) << presto->jtag_tdi_count;

		if (++presto->jtag_tdi_count == 4)
			presto_tdi_flush();

		return 0;
	}

	presto_tdi_flush();

	cmd = tdi ? 0xCB : 0xCA;
	presto_sendbyte(cmd);

	if (tms != presto->jtag_tms)
	{
		presto_sendbyte((tms ? 0xEC : 0xE8) | (presto->jtag_rst ? 0x02 : 0));
		presto->jtag_tms = tms;
	}

	/* delay with TCK low */
	for (i=presto->jtag_speed; i>1; i--)
		presto_sendbyte(cmd);

	cmd |= 0x04;
	presto_sendbyte(cmd | (tdo_req ? 0x10 : 0));

	/* delay with TCK high */
	for (i=presto->jtag_speed; i>1; i--)
		presto_sendbyte(cmd);

	presto->jtag_tck = 1;

	return 0;
}

static int presto_bitq_flush(void)
{
	presto_tdi_flush();
	presto_tck_idle();

	presto_sendbyte(0xA0); /* LED idicator - JTAG idle */

	return presto_flush();
}

static int presto_bitq_in_rdy(void)
{
	if (presto->buff_in_pos>=presto->buff_in_len)
		return 0;
	return presto->buff_in_len-presto->buff_in_pos;
}

static int presto_bitq_in(void)
{
	if (presto->buff_in_pos>=presto->buff_in_len)
		return -1;
	if (presto->buff_in[presto->buff_in_pos++]&0x08) return 1;
	return 0;
}

static int presto_bitq_sleep(unsigned long us)
{
	long waits;

	presto_tdi_flush();
	presto_tck_idle();

	if (us > 100000)
	{
		presto_bitq_flush();
		jtag_sleep(us);
		return 0;
	}

	waits = us / 170 + 2;
	while (waits--)
		presto_sendbyte(0x80);

	return 0;
}

static int presto_bitq_reset(int trst, int srst)
{
	presto_tdi_flush();
	presto_tck_idle();

	/* add a delay after possible TCK transition */
	presto_sendbyte(0x80);
	presto_sendbyte(0x80);

	presto->jtag_rst = trst || srst;
	presto_sendbyte((presto->jtag_rst ? 0xEA : 0xE8) | (presto->jtag_tms ? 0x04 : 0));

	return 0;
}

/* -------------------------------------------------------------------------- */

static int presto_jtag_khz(int khz, int *jtag_speed)
{
	if (khz < 0)
	{
		*jtag_speed=0;
		return ERROR_INVALID_ARGUMENTS;
	}

	if (khz >= 3000) *jtag_speed = 0;
	else *jtag_speed = (1000+khz-1)/khz;

	return 0;
}

static int presto_jtag_speed_div(int speed, int *khz)
{
	if ((speed < 0) || (speed > 1000))
	{
		*khz=0;
		return ERROR_INVALID_ARGUMENTS;
	}

	if (speed == 0) *khz = 3000;
	else *khz = 1000/speed;

	return 0;
}

static int presto_jtag_speed(int speed)
{
	int khz;

	if (presto_jtag_speed_div(speed, &khz))
	{
		return ERROR_INVALID_ARGUMENTS;
	}

	presto->jtag_speed = speed;

	if (khz%1000 == 0)
		LOG_INFO("setting speed to %d, max. TCK freq. is %d MHz", speed, khz/1000);
	else
		LOG_INFO("setting speed to %d, max. TCK freq. is %d kHz", speed, khz);

	return 0;
}

static char *presto_serial;

static int presto_handle_serial_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
{
	if (argc == 1)
	{
		if (presto_serial)
			free(presto_serial);
		presto_serial = strdup(args[0]);
	}
	else
	{
		LOG_ERROR("expected exactly one argument to presto_serial <serial-number>");
	}

	return ERROR_OK;
}

static int presto_jtag_register_commands(struct command_context_s *cmd_ctx)
{
	register_command(cmd_ctx, NULL, "presto_serial", presto_handle_serial_command,
		COMMAND_CONFIG, NULL);
	return ERROR_OK;
}

static int presto_jtag_init(void)
{
	if (presto_open(presto_serial) != ERROR_OK)
	{
		presto_close();
		if (presto_serial != NULL)
			LOG_ERROR("Cannot open PRESTO, serial number '%s'", presto_serial);
		else
			LOG_ERROR("Cannot open PRESTO");
		return ERROR_JTAG_INIT_FAILED;
	}
	LOG_INFO("PRESTO open, serial number '%s'", presto->serial);

	/* use JTAG speed setting from configuration file */
	presto_jtag_speed(jtag_get_speed());

	bitq_interface = &presto_bitq;
	return ERROR_OK;
}

static int presto_jtag_quit(void)
{
	bitq_cleanup();
	presto_close();
	LOG_INFO("PRESTO closed");

	if (presto_serial)
	{
		free(presto_serial);
		presto_serial = NULL;
	}

	return ERROR_OK;
}