Diagnostics tweaks for jtag_examine_chain() failure paths.

[openocd.git] / src / jtag / core.c

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007,2008 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   Copyright (C) 2009 SoftPLC Corporation                                *
 *       http://softplc.com                                                *
 *   dick@softplc.com                                                      *
 *                                                                         *
 *   Copyright (C) 2009 Zachary T Welch                                    *
 *   zw@superlucidity.net                                                  *
 *                                                                         *
 *   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 "jtag.h"
#include "minidriver.h"
#include "interface.h"

#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif


/// The number of JTAG queue flushes (for profiling and debugging purposes).
static int jtag_flush_queue_count;

static void jtag_add_scan_check(void (*jtag_add_scan)(int in_num_fields, const scan_field_t *in_fields, tap_state_t state),
                int in_num_fields, scan_field_t *in_fields, tap_state_t state);

/**
 * The jtag_error variable is set when an error occurs while executing
 * the queue.  Application code may set this using jtag_set_error(),
 * when an error occurs during processing that should be reported during
 * jtag_execute_queue().
 *
 * Tts value may be checked with jtag_get_error() and cleared with
 * jtag_error_clear().  This value is returned (and cleared) by
 * jtag_execute_queue().
 */
static int jtag_error = ERROR_OK;

static const char *jtag_event_strings[] =
{
        [JTAG_TRST_ASSERTED] = "TAP reset",
        [JTAG_TAP_EVENT_ENABLE] = "TAP enabled",
        [JTAG_TAP_EVENT_POST_RESET] = "TAP post reset",
        [JTAG_TAP_EVENT_DISABLE] = "TAP disabled",
};

/*
 * JTAG adapters must initialize with TRST and SRST de-asserted
 * (they're negative logic, so that means *high*)
 */
static int jtag_trst = 0;
static int jtag_srst = 0;

/**
 * List all TAPs that have been created.
 */
static jtag_tap_t *__jtag_all_taps = NULL;
/**
 * The number of TAPs in the __jtag_all_taps list, used to track the
 * assigned chain position to new TAPs
 */
static unsigned jtag_num_taps = 0;

static enum reset_types jtag_reset_config = RESET_NONE;
static tap_state_t cmd_queue_end_state = TAP_RESET;
tap_state_t cmd_queue_cur_state = TAP_RESET;

static bool jtag_verify_capture_ir = true;
static int jtag_verify = 1;

/* how long the OpenOCD should wait before attempting JTAG communication after reset lines deasserted (in ms) */
static int jtag_nsrst_delay = 0; /* default to no nSRST delay */
static int jtag_ntrst_delay = 0; /* default to no nTRST delay */

typedef struct jtag_event_callback_s
{
        jtag_event_handler_t          callback;
        void*                         priv;
        struct jtag_event_callback_s* next;
} jtag_event_callback_t;

/* callbacks to inform high-level handlers about JTAG state changes */
static jtag_event_callback_t *jtag_event_callbacks;

/* speed in kHz*/
static int speed_khz = 0;
/* speed to fallback to when RCLK is requested but not supported */
static int rclk_fallback_speed_khz = 0;
static enum {CLOCK_MODE_SPEED, CLOCK_MODE_KHZ, CLOCK_MODE_RCLK} clock_mode;
static int jtag_speed = 0;

static struct jtag_interface_s *jtag = NULL;

/* configuration */
jtag_interface_t *jtag_interface = NULL;

void jtag_set_error(int error)
{
        if ((error == ERROR_OK) || (jtag_error != ERROR_OK))
                return;
        jtag_error = error;
}
int jtag_get_error(void)
{
        return jtag_error;
}
int jtag_error_clear(void)
{
        int temp = jtag_error;
        jtag_error = ERROR_OK;
        return temp;
}


jtag_tap_t *jtag_all_taps(void)
{
        return __jtag_all_taps;
};

unsigned jtag_tap_count(void)
{
        return jtag_num_taps;
}

unsigned jtag_tap_count_enabled(void)
{
        jtag_tap_t *t = jtag_all_taps();
        unsigned n = 0;
        while (t)
        {
                if (t->enabled)
                        n++;
                t = t->next_tap;
        }
        return n;
}

/// Append a new TAP to the chain of all taps.
void jtag_tap_add(struct jtag_tap_s *t)
{
        t->abs_chain_position = jtag_num_taps++;

        jtag_tap_t **tap = &__jtag_all_taps;
        while (*tap != NULL)
                tap = &(*tap)->next_tap;
        *tap = t;
}

/* returns a pointer to the n-th device in the scan chain */
static inline jtag_tap_t *jtag_tap_by_position(unsigned n)
{
        jtag_tap_t *t = jtag_all_taps();

        while (t && n-- > 0)
                t = t->next_tap;

        return t;
}

jtag_tap_t *jtag_tap_by_string(const char *s)
{
        /* try by name first */
        jtag_tap_t *t = jtag_all_taps();

        while (t)
        {
                if (0 == strcmp(t->dotted_name, s))
                        return t;
                t = t->next_tap;
        }

        /* no tap found by name, so try to parse the name as a number */
        unsigned n;
        if (parse_uint(s, &n) != ERROR_OK)
                return NULL;

        /* FIXME remove this numeric fallback code late June 2010, along
         * with all info in the User's Guide that TAPs have numeric IDs.
         * Also update "scan_chain" output to not display the numbers.
         */
        t = jtag_tap_by_position(n);
        if (t)
                LOG_WARNING("Specify TAP '%s' by name, not number %u",
                        t->dotted_name, n);

        return t;
}

jtag_tap_t *jtag_tap_by_jim_obj(Jim_Interp *interp, Jim_Obj *o)
{
        const char *cp = Jim_GetString(o, NULL);
        jtag_tap_t *t = cp ? jtag_tap_by_string(cp) : NULL;
        if (NULL == cp)
                cp = "(unknown)";
        if (NULL == t)
                Jim_SetResult_sprintf(interp, "Tap '%s' could not be found", cp);
        return t;
}

jtag_tap_t* jtag_tap_next_enabled(jtag_tap_t* p)
{
        p = p ? p->next_tap : jtag_all_taps();
        while (p)
        {
                if (p->enabled)
                        return p;
                p = p->next_tap;
        }
        return NULL;
}

const char *jtag_tap_name(const jtag_tap_t *tap)
{
        return (tap == NULL) ? "(unknown)" : tap->dotted_name;
}


int jtag_register_event_callback(jtag_event_handler_t callback, void *priv)
{
        jtag_event_callback_t **callbacks_p = &jtag_event_callbacks;

        if (callback == NULL)
        {
                return ERROR_INVALID_ARGUMENTS;
        }

        if (*callbacks_p)
        {
                while ((*callbacks_p)->next)
                        callbacks_p = &((*callbacks_p)->next);
                callbacks_p = &((*callbacks_p)->next);
        }

        (*callbacks_p) = malloc(sizeof(jtag_event_callback_t));
        (*callbacks_p)->callback = callback;
        (*callbacks_p)->priv = priv;
        (*callbacks_p)->next = NULL;

        return ERROR_OK;
}

int jtag_unregister_event_callback(jtag_event_handler_t callback, void *priv)
{
        jtag_event_callback_t **callbacks_p;
        jtag_event_callback_t **next;

        if (callback == NULL)
        {
                return ERROR_INVALID_ARGUMENTS;
        }

        for (callbacks_p = &jtag_event_callbacks;
                        *callbacks_p != NULL;
                        callbacks_p = next)
        {
                next = &((*callbacks_p)->next);

                if ((*callbacks_p)->priv != priv)
                        continue;

                if ((*callbacks_p)->callback == callback)
                {
                        free(*callbacks_p);
                        *callbacks_p = *next;
                }
        }

        return ERROR_OK;
}

int jtag_call_event_callbacks(enum jtag_event event)
{
        jtag_event_callback_t *callback = jtag_event_callbacks;

        LOG_DEBUG("jtag event: %s", jtag_event_strings[event]);

        while (callback)
        {
                jtag_event_callback_t *next;

                /* callback may remove itself */
                next = callback->next;
                callback->callback(event, callback->priv);
                callback = next;
        }

        return ERROR_OK;
}

static void jtag_checks(void)
{
        assert(jtag_trst == 0);
}

static void jtag_prelude(tap_state_t state)
{
        jtag_checks();

        assert(state != TAP_INVALID);

        cmd_queue_cur_state = state;
}

void jtag_alloc_in_value32(scan_field_t *field)
{
        interface_jtag_alloc_in_value32(field);
}

void jtag_add_ir_scan_noverify(int in_count, const scan_field_t *in_fields,
                tap_state_t state)
{
        jtag_prelude(state);

        int retval = interface_jtag_add_ir_scan(in_count, in_fields, state);
        jtag_set_error(retval);
}


void jtag_add_ir_scan(int in_num_fields, scan_field_t *in_fields, tap_state_t state)
{
        assert(state != TAP_RESET);

        if (jtag_verify && jtag_verify_capture_ir)
        {
                /* 8 x 32 bit id's is enough for all invocations */

                for (int j = 0; j < in_num_fields; j++)
                {
                        /* if we are to run a verification of the ir scan, we need to get the input back.
                         * We may have to allocate space if the caller didn't ask for the input back.
                         */
                        in_fields[j].check_value = in_fields[j].tap->expected;
                        in_fields[j].check_mask = in_fields[j].tap->expected_mask;
                }
                jtag_add_scan_check(jtag_add_ir_scan_noverify, in_num_fields, in_fields, state);
        } else
        {
                jtag_add_ir_scan_noverify(in_num_fields, in_fields, state);
        }
}

void jtag_add_plain_ir_scan(int in_num_fields, const scan_field_t *in_fields,
                tap_state_t state)
{
        assert(state != TAP_RESET);

        jtag_prelude(state);

        int retval = interface_jtag_add_plain_ir_scan(
                        in_num_fields, in_fields, state);
        jtag_set_error(retval);
}

void jtag_add_callback(jtag_callback1_t f, jtag_callback_data_t data0)
{
        interface_jtag_add_callback(f, data0);
}

void jtag_add_callback4(jtag_callback_t f, jtag_callback_data_t data0,
                jtag_callback_data_t data1, jtag_callback_data_t data2,
                jtag_callback_data_t data3)
{
        interface_jtag_add_callback4(f, data0, data1, data2, data3);
}

static int jtag_check_value_inner(uint8_t *captured, uint8_t *in_check_value,
                uint8_t *in_check_mask, int num_bits);

static int jtag_check_value_mask_callback(jtag_callback_data_t data0, jtag_callback_data_t data1, jtag_callback_data_t data2, jtag_callback_data_t data3)
{
        return jtag_check_value_inner((uint8_t *)data0, (uint8_t *)data1, (uint8_t *)data2, (int)data3);
}

static void jtag_add_scan_check(void (*jtag_add_scan)(int in_num_fields, const scan_field_t *in_fields, tap_state_t state),
                int in_num_fields, scan_field_t *in_fields, tap_state_t state)
{
        for (int i = 0; i < in_num_fields; i++)
        {
                struct scan_field_s *field = &in_fields[i];
                field->allocated = 0;
                field->modified = 0;
                if (field->check_value || field->in_value)
                        continue;
                interface_jtag_add_scan_check_alloc(field);
                field->modified = 1;
        }

        jtag_add_scan(in_num_fields, in_fields, state);

        for (int i = 0; i < in_num_fields; i++)
        {
                if ((in_fields[i].check_value != NULL) && (in_fields[i].in_value != NULL))
                {
                        /* this is synchronous for a minidriver */
                        jtag_add_callback4(jtag_check_value_mask_callback, (jtag_callback_data_t)in_fields[i].in_value,
                                (jtag_callback_data_t)in_fields[i].check_value,
                                (jtag_callback_data_t)in_fields[i].check_mask,
                                (jtag_callback_data_t)in_fields[i].num_bits);
                }
                if (in_fields[i].allocated)
                {
                        free(in_fields[i].in_value);
                }
                if (in_fields[i].modified)
                {
                        in_fields[i].in_value = NULL;
                }
        }
}

void jtag_add_dr_scan_check(int in_num_fields, scan_field_t *in_fields, tap_state_t state)
{
        if (jtag_verify)
        {
                jtag_add_scan_check(jtag_add_dr_scan, in_num_fields, in_fields, state);
        } else
        {
                jtag_add_dr_scan(in_num_fields, in_fields, state);
        }
}


void jtag_add_dr_scan(int in_num_fields, const scan_field_t *in_fields,
                tap_state_t state)
{
        assert(state != TAP_RESET);

        jtag_prelude(state);

        int retval;
        retval = interface_jtag_add_dr_scan(in_num_fields, in_fields, state);
        jtag_set_error(retval);
}

void jtag_add_plain_dr_scan(int in_num_fields, const scan_field_t *in_fields,
                tap_state_t state)
{
        assert(state != TAP_RESET);

        jtag_prelude(state);

        int retval;
        retval = interface_jtag_add_plain_dr_scan(in_num_fields, in_fields, state);
        jtag_set_error(retval);
}

void jtag_add_dr_out(jtag_tap_t* tap,
                int num_fields, const int* num_bits, const uint32_t* value,
                tap_state_t end_state)
{
        assert(end_state != TAP_RESET);
        assert(end_state != TAP_INVALID);

        cmd_queue_cur_state = end_state;

        interface_jtag_add_dr_out(tap,
                        num_fields, num_bits, value,
                        end_state);
}

void jtag_add_tlr(void)
{
        jtag_prelude(TAP_RESET);
        jtag_set_error(interface_jtag_add_tlr());

        /* NOTE: order here matches TRST path in jtag_add_reset() */
        jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
        jtag_notify_reset();
}

void jtag_add_pathmove(int num_states, const tap_state_t *path)
{
        tap_state_t cur_state = cmd_queue_cur_state;

        /* the last state has to be a stable state */
        if (!tap_is_state_stable(path[num_states - 1]))
        {
                LOG_ERROR("BUG: TAP path doesn't finish in a stable state");
                jtag_set_error(ERROR_JTAG_NOT_STABLE_STATE);
                return;
        }

        for (int i = 0; i < num_states; i++)
        {
                if (path[i] == TAP_RESET)
                {
                        LOG_ERROR("BUG: TAP_RESET is not a valid state for pathmove sequences");
                        jtag_set_error(ERROR_JTAG_STATE_INVALID);
                        return;
                }

                if (tap_state_transition(cur_state, true)  != path[i]
                  && tap_state_transition(cur_state, false) != path[i])
                {
                        LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition",
                                        tap_state_name(cur_state), tap_state_name(path[i]));
                        jtag_set_error(ERROR_JTAG_TRANSITION_INVALID);
                        return;
                }
                cur_state = path[i];
        }

        jtag_checks();

        jtag_set_error(interface_jtag_add_pathmove(num_states, path));
        cmd_queue_cur_state = path[num_states - 1];
}

int jtag_add_statemove(tap_state_t goal_state)
{
        tap_state_t cur_state = cmd_queue_cur_state;

        LOG_DEBUG("cur_state=%s goal_state=%s",
                tap_state_name(cur_state),
                tap_state_name(goal_state));


        if (goal_state == cur_state)
                ;       /* nothing to do */
        else if (goal_state == TAP_RESET)
        {
                jtag_add_tlr();
        }
        else if (tap_is_state_stable(cur_state) && tap_is_state_stable(goal_state))
        {
                unsigned tms_bits  = tap_get_tms_path(cur_state, goal_state);
                unsigned tms_count = tap_get_tms_path_len(cur_state, goal_state);
                tap_state_t moves[8];
                assert(tms_count < DIM(moves));

                for (unsigned i = 0; i < tms_count; i++, tms_bits >>= 1)
                {
                        bool bit = tms_bits & 1;

                        cur_state = tap_state_transition(cur_state, bit);
                        moves[i] = cur_state;
                }

                jtag_add_pathmove(tms_count, moves);
        }
        else if (tap_state_transition(cur_state, true)  == goal_state
                ||   tap_state_transition(cur_state, false) == goal_state)
        {
                jtag_add_pathmove(1, &goal_state);
        }

        else
                return ERROR_FAIL;

        return ERROR_OK;
}

void jtag_add_runtest(int num_cycles, tap_state_t state)
{
        jtag_prelude(state);
        jtag_set_error(interface_jtag_add_runtest(num_cycles, state));
}


void jtag_add_clocks(int num_cycles)
{
        if (!tap_is_state_stable(cmd_queue_cur_state))
        {
                 LOG_ERROR("jtag_add_clocks() called with TAP in unstable state \"%s\"",
                                 tap_state_name(cmd_queue_cur_state));
                 jtag_set_error(ERROR_JTAG_NOT_STABLE_STATE);
                 return;
        }

        if (num_cycles > 0)
        {
                jtag_checks();
                jtag_set_error(interface_jtag_add_clocks(num_cycles));
        }
}

void jtag_add_reset(int req_tlr_or_trst, int req_srst)
{
        int trst_with_tlr = 0;
        int new_srst = 0;
        int new_trst = 0;

        /* Without SRST, we must use target-specific JTAG operations
         * on each target; callers should not be requesting SRST when
         * that signal doesn't exist.
         *
         * RESET_SRST_PULLS_TRST is a board or chip level quirk, which
         * can kick in even if the JTAG adapter can't drive TRST.
         */
        if (req_srst) {
                if (!(jtag_reset_config & RESET_HAS_SRST)) {
                        LOG_ERROR("BUG: can't assert SRST");
                        jtag_set_error(ERROR_FAIL);
                        return;
                }
                if ((jtag_reset_config & RESET_SRST_PULLS_TRST) != 0
                                && !req_tlr_or_trst) {
                        LOG_ERROR("BUG: can't assert only SRST");
                        jtag_set_error(ERROR_FAIL);
                        return;
                }
                new_srst = 1;
        }

        /* JTAG reset (entry to TAP_RESET state) can always be achieved
         * using TCK and TMS; that may go through a TAP_{IR,DR}UPDATE
         * state first.  TRST accelerates it, and bypasses those states.
         *
         * RESET_TRST_PULLS_SRST is a board or chip level quirk, which
         * can kick in even if the JTAG adapter can't drive SRST.
         */
        if (req_tlr_or_trst) {
                if (!(jtag_reset_config & RESET_HAS_TRST))
                        trst_with_tlr = 1;
                else if ((jtag_reset_config & RESET_TRST_PULLS_SRST) != 0
                                && !req_srst)
                        trst_with_tlr = 1;
                else
                        new_trst = 1;
        }

        /* Maybe change TRST and/or SRST signal state */
        if (jtag_srst != new_srst || jtag_trst != new_trst) {
                int retval;

                retval = interface_jtag_add_reset(new_trst, new_srst);
                if (retval != ERROR_OK)
                        jtag_set_error(retval);
                else
                        retval = jtag_execute_queue();

                if (retval != ERROR_OK) {
                        LOG_ERROR("TRST/SRST error %d", retval);
                        return;
                }
        }

        /* SRST resets everything hooked up to that signal */
        if (jtag_srst != new_srst) {
                jtag_srst = new_srst;
                if (jtag_srst)
                        LOG_DEBUG("SRST line asserted");
                else {
                        LOG_DEBUG("SRST line released");
                        if (jtag_nsrst_delay)
                                jtag_add_sleep(jtag_nsrst_delay * 1000);
                }
        }

        /* Maybe enter the JTAG TAP_RESET state ...
         *  - using only TMS, TCK, and the JTAG state machine
         *  - or else more directly, using TRST
         *
         * TAP_RESET should be invisible to non-debug parts of the system.
         */
        if (trst_with_tlr) {
                LOG_DEBUG("JTAG reset with TLR instead of TRST");
                jtag_set_end_state(TAP_RESET);
                jtag_add_tlr();

        } else if (jtag_trst != new_trst) {
                jtag_trst = new_trst;
                if (jtag_trst) {
                        LOG_DEBUG("TRST line asserted");
                        tap_set_state(TAP_RESET);
                } else {
                        LOG_DEBUG("TRST line released");
                        if (jtag_ntrst_delay)
                                jtag_add_sleep(jtag_ntrst_delay * 1000);

                        /* We just asserted nTRST, so we're now in TAP_RESET.
                         * Inform possible listeners about this, now that
                         * JTAG instructions and data can be shifted.  This
                         * sequence must match jtag_add_tlr().
                         */
                        jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
                        jtag_notify_reset();
                }
        }
}

tap_state_t jtag_set_end_state(tap_state_t state)
{
        if ((state == TAP_DRSHIFT)||(state == TAP_IRSHIFT))
        {
                LOG_ERROR("BUG: TAP_DRSHIFT/IRSHIFT can't be end state. Calling code should use a larger scan field");
        }

        if (state != TAP_INVALID)
                cmd_queue_end_state = state;
        return cmd_queue_end_state;
}

tap_state_t jtag_get_end_state(void)
{
        return cmd_queue_end_state;
}

void jtag_add_sleep(uint32_t us)
{
        /// @todo Here, keep_alive() appears to be a layering violation!!!
        keep_alive();
        jtag_set_error(interface_jtag_add_sleep(us));
}

static int jtag_check_value_inner(uint8_t *captured, uint8_t *in_check_value,
                uint8_t *in_check_mask, int num_bits)
{
        int retval = ERROR_OK;

        int compare_failed = 0;

        if (in_check_mask)
                compare_failed = buf_cmp_mask(captured, in_check_value, in_check_mask, num_bits);
        else
                compare_failed = buf_cmp(captured, in_check_value, num_bits);

        if (compare_failed) {
                char *captured_str, *in_check_value_str;
                int bits = (num_bits > DEBUG_JTAG_IOZ)
                                ? DEBUG_JTAG_IOZ
                                : num_bits;

                /* NOTE:  we've lost diagnostic context here -- 'which tap' */

                captured_str = buf_to_str(captured, bits, 16);
                in_check_value_str = buf_to_str(in_check_value, bits, 16);

                LOG_WARNING("Bad value '%s' captured during DR or IR scan:",
                                captured_str);
                LOG_WARNING(" check_value: 0x%s", in_check_value_str);

                free(captured_str);
                free(in_check_value_str);

                if (in_check_mask) {
                        char *in_check_mask_str;

                        in_check_mask_str = buf_to_str(in_check_mask, bits, 16);
                        LOG_WARNING(" check_mask: 0x%s", in_check_mask_str);
                        free(in_check_mask_str);
                }

                retval = ERROR_JTAG_QUEUE_FAILED;
        }
        return retval;
}

void jtag_check_value_mask(scan_field_t *field, uint8_t *value, uint8_t *mask)
{
        assert(field->in_value != NULL);

        if (value == NULL)
        {
                /* no checking to do */
                return;
        }

        jtag_execute_queue_noclear();

        int retval = jtag_check_value_inner(field->in_value, value, mask, field->num_bits);
        jtag_set_error(retval);
}



int default_interface_jtag_execute_queue(void)
{
        if (NULL == jtag)
        {
                LOG_ERROR("No JTAG interface configured yet.  "
                        "Issue 'init' command in startup scripts "
                        "before communicating with targets.");
                return ERROR_FAIL;
        }

        return jtag->execute_queue();
}

void jtag_execute_queue_noclear(void)
{
        jtag_flush_queue_count++;
        jtag_set_error(interface_jtag_execute_queue());
}

int jtag_get_flush_queue_count(void)
{
        return jtag_flush_queue_count;
}

int jtag_execute_queue(void)
{
        jtag_execute_queue_noclear();
        return jtag_error_clear();
}

static int jtag_reset_callback(enum jtag_event event, void *priv)
{
        jtag_tap_t *tap = priv;

        if (event == JTAG_TRST_ASSERTED)
        {
                tap->enabled = !tap->disabled_after_reset;

                /* current instruction is either BYPASS or IDCODE */
                buf_set_ones(tap->cur_instr, tap->ir_length);
                tap->bypass = 1;
        }

        return ERROR_OK;
}

void jtag_sleep(uint32_t us)
{
        alive_sleep(us/1000);
}

/* Maximum number of enabled JTAG devices we expect in the scan chain,
 * plus one (to detect garbage at the end).  Devices that don't support
 * IDCODE take up fewer bits, possibly allowing a few more devices.
 */
#define JTAG_MAX_CHAIN_SIZE 20

#define EXTRACT_MFG(X)  (((X) & 0xffe) >> 1)
#define EXTRACT_PART(X) (((X) & 0xffff000) >> 12)
#define EXTRACT_VER(X)  (((X) & 0xf0000000) >> 28)

/* A reserved manufacturer ID is used in END_OF_CHAIN_FLAG, so we
 * know that no valid TAP will have it as an IDCODE value.
 */
#define END_OF_CHAIN_FLAG       0x000000ff

static int jtag_examine_chain_execute(uint8_t *idcode_buffer, unsigned num_idcode)
{
        scan_field_t field = {
                        .tap = NULL,
                        .num_bits = num_idcode * 32,
                        .out_value = idcode_buffer,
                        .in_value = idcode_buffer,
                };

        // initialize to the end of chain ID value
        for (unsigned i = 0; i < JTAG_MAX_CHAIN_SIZE; i++)
                buf_set_u32(idcode_buffer, i * 32, 32, END_OF_CHAIN_FLAG);

        jtag_add_plain_dr_scan(1, &field, TAP_DRPAUSE);
        jtag_add_tlr();
        return jtag_execute_queue();
}

static bool jtag_examine_chain_check(uint8_t *idcodes, unsigned count)
{
        uint8_t zero_check = 0x0;
        uint8_t one_check = 0xff;

        for (unsigned i = 0; i < count * 4; i++)
        {
                zero_check |= idcodes[i];
                one_check &= idcodes[i];
        }

        /* if there wasn't a single non-zero bit or if all bits were one,
         * the scan is not valid */
        if (zero_check == 0x00 || one_check == 0xff)
        {
                LOG_ERROR("JTAG scan chain interrogation failed: all %s",
                                (zero_check == 0x00) ? "zeroes" : "ones");
                LOG_ERROR("Check JTAG interface, timings, target power, etc.");
                return false;
        }
        return true;
}

static void jtag_examine_chain_display(enum log_levels level, const char *msg,
                const char *name, uint32_t idcode)
{
        log_printf_lf(level, __FILE__, __LINE__, __FUNCTION__,
                                  "JTAG tap: %s %16.16s: 0x%08x "
                                  "(mfg: 0x%3.3x, part: 0x%4.4x, ver: 0x%1.1x)",
                                  name, msg,
                                  (unsigned int)idcode,
                                  (unsigned int)EXTRACT_MFG(idcode),
                                  (unsigned int)EXTRACT_PART(idcode),
                                  (unsigned int)EXTRACT_VER(idcode));
}

static bool jtag_idcode_is_final(uint32_t idcode)
{
        /*
         * Some devices, such as AVR8, will output all 1's instead
         * of TDI input value at end of chain.  Allow those values
         * instead of failing.
         */
        return idcode == END_OF_CHAIN_FLAG || idcode == 0xFFFFFFFF;
}

/**
 * This helper checks that remaining bits in the examined chain data are
 * all as expected, but a single JTAG device requires only 64 bits to be
 * read back correctly.  This can help identify and diagnose problems
 * with the JTAG chain earlier, gives more helpful/explicit error messages.
 * Returns TRUE iff garbage was found.
 */
static bool jtag_examine_chain_end(uint8_t *idcodes, unsigned count, unsigned max)
{
        bool triggered = false;
        for (; count < max - 31; count += 32)
        {
                uint32_t idcode = buf_get_u32(idcodes, count, 32);
                // do not trigger the warning if the data looks good
                if (!triggered && jtag_idcode_is_final(idcode))
                        continue;
                LOG_WARNING("Unexpected idcode after end of chain: %d 0x%08x",
                                        count, (unsigned int)idcode);
                triggered = true;
        }
        return triggered;
}

static bool jtag_examine_chain_match_tap(const struct jtag_tap_s *tap)
{
        /* ignore expected BYPASS codes; warn otherwise */
        if (0 == tap->expected_ids_cnt && !tap->idcode)
                return true;

        /* Loop over the expected identification codes and test for a match */
        uint8_t ii;
        for (ii = 0; ii < tap->expected_ids_cnt; ii++)
        {
                if (tap->idcode == tap->expected_ids[ii])
                        return true;
        }

        /* If none of the expected ids matched, log an error */
        jtag_examine_chain_display(LOG_LVL_ERROR, "UNEXPECTED",
                        tap->dotted_name, tap->idcode);
        for (ii = 0; ii < tap->expected_ids_cnt; ii++)
        {
                char msg[32];
                snprintf(msg, sizeof(msg), "expected %hhu of %hhu",
                                ii + 1, tap->expected_ids_cnt);
                jtag_examine_chain_display(LOG_LVL_ERROR, msg,
                                tap->dotted_name, tap->expected_ids[ii]);
        }
        return false;
}

/* Try to examine chain layout according to IEEE 1149.1 §12
 * This is called a "blind interrogation" of the scan chain.
 */
static int jtag_examine_chain(void)
{
        uint8_t idcode_buffer[JTAG_MAX_CHAIN_SIZE * 4];
        unsigned bit_count;

        /* DR scan to collect BYPASS or IDCODE register contents.
         * Then make sure the scan data has both ones and zeroes.
         */
        jtag_examine_chain_execute(idcode_buffer, JTAG_MAX_CHAIN_SIZE);
        if (!jtag_examine_chain_check(idcode_buffer, JTAG_MAX_CHAIN_SIZE))
                return ERROR_JTAG_INIT_FAILED;

        /* point at the 1st tap */
        jtag_tap_t *tap = jtag_tap_next_enabled(NULL);
        if (tap == NULL)
        {
                LOG_ERROR("JTAG: No taps enabled?");
                return ERROR_JTAG_INIT_FAILED;
        }

        for (bit_count = 0;
                        tap && bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31;
                        tap = jtag_tap_next_enabled(tap))
        {
                uint32_t idcode = buf_get_u32(idcode_buffer, bit_count, 32);

                if ((idcode & 1) == 0)
                {
                        /* LSB must not be 0, this indicates a device in bypass */
                        LOG_WARNING("TAP %s does not have IDCODE",
                                        tap->dotted_name);
                        idcode = 0;
                        tap->hasidcode = false;

                        bit_count += 1;
                }
                else
                {
                        /* Friendly devices support IDCODE */
                        tap->hasidcode = true;
                        jtag_examine_chain_display(LOG_LVL_INFO, "tap/device found",
                                        tap->dotted_name, idcode);

                        bit_count += 32;
                }
                tap->idcode = idcode;

                // ensure the TAP ID does matches what was expected
                if (!jtag_examine_chain_match_tap(tap))
                        return ERROR_JTAG_INIT_FAILED;
        }

        /* Fail if too many TAPs were enabled for us to verify them all. */
        if (tap) {
                LOG_ERROR("Too many TAPs enabled; '%s' ignored.",
                                tap->dotted_name);
                return ERROR_JTAG_INIT_FAILED;
        }

        /* After those IDCODE or BYPASS register values should be
         * only the data we fed into the scan chain.
         */
        if (jtag_examine_chain_end(idcode_buffer, bit_count,
                        8 * sizeof(idcode_buffer))) {
                LOG_ERROR("double-check your JTAG setup (interface, "
                                "speed, TAPs, ...)");
                return ERROR_JTAG_INIT_FAILED;
        }

        return ERROR_OK;
}

/*
 * Validate the date loaded by entry to the Capture-IR state, to help
 * find errors related to scan chain configuration (wrong IR lengths)
 * or communication.
 */
static int jtag_validate_ircapture(void)
{
        jtag_tap_t *tap;
        int total_ir_length = 0;
        uint8_t *ir_test = NULL;
        scan_field_t field;
        int chain_pos = 0;

        tap = NULL;
        total_ir_length = 0;
        for (;;) {
                tap = jtag_tap_next_enabled(tap);
                if (tap == NULL) {
                        break;
                }
                total_ir_length += tap->ir_length;
        }

        total_ir_length += 2;

        ir_test = malloc(CEIL(total_ir_length, 8));
        if (ir_test == NULL)
                return ERROR_FAIL;

        buf_set_ones(ir_test, total_ir_length);

        field.tap = NULL;
        field.num_bits = total_ir_length;
        field.out_value = ir_test;
        field.in_value = ir_test;


        jtag_add_plain_ir_scan(1, &field, TAP_IRPAUSE);
        jtag_add_tlr();

        int retval;
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
                return retval;

        tap = NULL;
        chain_pos = 0;
        int val;
        for (;;) {
                tap = jtag_tap_next_enabled(tap);
                if (tap == NULL) {
                        break;
                }

                /* Validate the two LSBs, which must be 01 per JTAG spec.
                 * REVISIT we might be able to verify some MSBs too, using
                 * ircapture/irmask attributes.
                 */
                val = buf_get_u32(ir_test, chain_pos, 2);
                if (val != 1) {
                        char *cbuf = buf_to_str(ir_test, total_ir_length, 16);

                        LOG_ERROR("%s: IR capture error; saw 0x%s not 0x..1",
                                        jtag_tap_name(tap), cbuf);

                        /* Fail only if we have IDCODE for this device.
                         * REVISIT -- why not fail-always?
                         */
                        if (tap->hasidcode) {
                                free(cbuf);
                                free(ir_test);
                                return ERROR_JTAG_INIT_FAILED;
                        }
                }
                chain_pos += tap->ir_length;
        }

        /* verify the '11' sentinel we wrote is returned at the end */
        val = buf_get_u32(ir_test, chain_pos, 2);
        if (val != 0x3)
        {
                char *cbuf = buf_to_str(ir_test, total_ir_length, 16);

                LOG_ERROR("IR capture error at bit %d, saw 0x%s not 0x...3",
                                chain_pos, cbuf);
                free(cbuf);
                free(ir_test);
                return ERROR_JTAG_INIT_FAILED;
        }

        free(ir_test);

        return ERROR_OK;
}


void jtag_tap_init(jtag_tap_t *tap)
{
        assert(0 != tap->ir_length);

        /// @todo fix, this allocates one byte per bit for all three fields!
        tap->expected = malloc(tap->ir_length);
        tap->expected_mask = malloc(tap->ir_length);
        tap->cur_instr = malloc(tap->ir_length);

        /// @todo cope sanely with ir_length bigger than 32 bits
        buf_set_u32(tap->expected, 0, tap->ir_length, tap->ir_capture_value);
        buf_set_u32(tap->expected_mask, 0, tap->ir_length, tap->ir_capture_mask);
        buf_set_ones(tap->cur_instr, tap->ir_length);

        // place TAP in bypass mode
        tap->bypass = 1;
        // register the reset callback for the TAP
        jtag_register_event_callback(&jtag_reset_callback, tap);

        LOG_DEBUG("Created Tap: %s @ abs position %d, "
                        "irlen %d, capture: 0x%x mask: 0x%x", tap->dotted_name,
                                tap->abs_chain_position, tap->ir_length,
                                (unsigned) tap->ir_capture_value,
                                (unsigned) tap->ir_capture_mask);
        jtag_tap_add(tap);
}

void jtag_tap_free(jtag_tap_t *tap)
{
        jtag_unregister_event_callback(&jtag_reset_callback, tap);

        /// @todo is anything missing? no memory leaks please
        free((void *)tap->expected);
        free((void *)tap->expected_ids);
        free((void *)tap->chip);
        free((void *)tap->tapname);
        free((void *)tap->dotted_name);
        free(tap);
}

int jtag_interface_init(struct command_context_s *cmd_ctx)
{
        if (jtag)
                return ERROR_OK;

        if (!jtag_interface)
        {
                /* nothing was previously specified by "interface" command */
                LOG_ERROR("JTAG interface has to be specified, see \"interface\" command");
                return ERROR_JTAG_INVALID_INTERFACE;
        }

        jtag = jtag_interface;
        if (jtag_interface->init() != ERROR_OK)
        {
                jtag = NULL;
                return ERROR_JTAG_INIT_FAILED;
        }

        int requested_khz = jtag_get_speed_khz();
        int actual_khz = requested_khz;
        int retval = jtag_get_speed_readable(&actual_khz);
        if (ERROR_OK != retval)
                LOG_INFO("interface specific clock speed value %d", jtag_get_speed());
        else if (actual_khz)
        {
                if ((CLOCK_MODE_RCLK == clock_mode)
                        || ((CLOCK_MODE_KHZ == clock_mode) && !requested_khz))
                {
                        LOG_INFO("RCLK (adaptive clock speed) not supported - fallback to %d kHz"
                                , actual_khz);
                }
                else
                        LOG_INFO("clock speed %d kHz", actual_khz);
        }
        else
                LOG_INFO("RCLK (adaptive clock speed)");

        return ERROR_OK;
}

static int jtag_init_inner(struct command_context_s *cmd_ctx)
{
        jtag_tap_t *tap;
        int retval;

        LOG_DEBUG("Init JTAG chain");

        tap = jtag_tap_next_enabled(NULL);
        if (tap == NULL) {
                LOG_ERROR("There are no enabled taps?");
                return ERROR_JTAG_INIT_FAILED;
        }

        jtag_add_tlr();
        if ((retval = jtag_execute_queue()) != ERROR_OK)
                return retval;

        /* examine chain first, as this could discover the real chain layout */
        if (jtag_examine_chain() != ERROR_OK)
        {
                LOG_ERROR("Trying to use configured scan chain anyway...");
        }

        if (jtag_validate_ircapture() != ERROR_OK)
        {
                LOG_WARNING("Errors during IR capture, continuing anyway...");
        }

        return ERROR_OK;
}

int jtag_interface_quit(void)
{
        if (!jtag || !jtag->quit)
                return ERROR_OK;

        // close the JTAG interface
        int result = jtag->quit();
        if (ERROR_OK != result)
                LOG_ERROR("failed: %d", result);

        return ERROR_OK;
}


int jtag_init_reset(struct command_context_s *cmd_ctx)
{
        int retval;

        if ((retval = jtag_interface_init(cmd_ctx)) != ERROR_OK)
                return retval;

        LOG_DEBUG("Trying to bring the JTAG controller to life by asserting TRST / TLR");

        /* Reset can happen after a power cycle.
         *
         * Ideally we would only assert TRST or run TLR before the target reset.
         *
         * However w/srst_pulls_trst, trst is asserted together with the target
         * reset whether we want it or not.
         *
         * NB! Some targets have JTAG circuitry disabled until a
         * trst & srst has been asserted.
         *
         * NB! here we assume nsrst/ntrst delay are sufficient!
         *
         * NB! order matters!!!! srst *can* disconnect JTAG circuitry
         *
         */
        jtag_add_reset(1, 0); /* TAP_RESET, using TMS+TCK or TRST */
        if (jtag_reset_config & RESET_HAS_SRST)
        {
                jtag_add_reset(1, 1);
                if ((jtag_reset_config & RESET_SRST_PULLS_TRST) == 0)
                        jtag_add_reset(0, 1);
        }
        jtag_add_reset(0, 0);
        if ((retval = jtag_execute_queue()) != ERROR_OK)
                return retval;

        /* Check that we can communication on the JTAG chain + eventually we want to
         * be able to perform enumeration only after OpenOCD has started
         * telnet and GDB server
         *
         * That would allow users to more easily perform any magic they need to before
         * reset happens.
         */
        return jtag_init_inner(cmd_ctx);
}

int jtag_init(struct command_context_s *cmd_ctx)
{
        int retval;
        if ((retval = jtag_interface_init(cmd_ctx)) != ERROR_OK)
                return retval;
        if (jtag_init_inner(cmd_ctx) == ERROR_OK)
        {
                return ERROR_OK;
        }
        return jtag_init_reset(cmd_ctx);
}

unsigned jtag_get_speed_khz(void)
{
        return speed_khz;
}

static int jtag_khz_to_speed(unsigned khz, int* speed)
{
        LOG_DEBUG("convert khz to interface specific speed value");
        speed_khz = khz;
        if (jtag != NULL)
        {
                LOG_DEBUG("have interface set up");
                int speed_div1;
                int retval = jtag->khz(jtag_get_speed_khz(), &speed_div1);
                if (ERROR_OK != retval)
                {
                        return retval;
                }
                *speed = speed_div1;
        }
        return ERROR_OK;
}

static int jtag_rclk_to_speed(unsigned fallback_speed_khz, int* speed)
{
        int retval = jtag_khz_to_speed(0, speed);
        if ((ERROR_OK != retval) && fallback_speed_khz)
        {
                LOG_DEBUG("trying fallback speed...");
                retval = jtag_khz_to_speed(fallback_speed_khz, speed);
        }
        return retval;
}

static int jtag_set_speed(int speed)
{
        jtag_speed = speed;
        /* this command can be called during CONFIG,
         * in which case jtag isn't initialized */
        return jtag ? jtag->speed(speed) : ERROR_OK;
}

int jtag_config_speed(int speed)
{
        LOG_DEBUG("handle jtag speed");
        clock_mode = CLOCK_MODE_SPEED;
        return jtag_set_speed(speed);
}

int jtag_config_khz(unsigned khz)
{
        LOG_DEBUG("handle jtag khz");
        clock_mode = CLOCK_MODE_KHZ;
        int speed = 0;
        int retval = jtag_khz_to_speed(khz, &speed);
        return (ERROR_OK != retval) ? retval : jtag_set_speed(speed);
}

int jtag_config_rclk(unsigned fallback_speed_khz)
{
        LOG_DEBUG("handle jtag rclk");
        clock_mode = CLOCK_MODE_RCLK;
        rclk_fallback_speed_khz = fallback_speed_khz;
        int speed = 0;
        int retval = jtag_rclk_to_speed(fallback_speed_khz, &speed);
        return (ERROR_OK != retval) ? retval : jtag_set_speed(speed);
}

int jtag_get_speed(void)
{
        int speed;
        switch(clock_mode)
        {
                case CLOCK_MODE_SPEED:
                        speed = jtag_speed;
                        break;
                case CLOCK_MODE_KHZ:
                        jtag_khz_to_speed(jtag_get_speed_khz(), &speed);
                        break;
                case CLOCK_MODE_RCLK:
                        jtag_rclk_to_speed(rclk_fallback_speed_khz, &speed);
                        break;
                default:
                        LOG_ERROR("BUG: unknown jtag clock mode");
                        speed = 0;
                        break;
        }
        return speed;
}

int jtag_get_speed_readable(int *khz)
{
        return jtag ? jtag->speed_div(jtag_get_speed(), khz) : ERROR_OK;
}

void jtag_set_verify(bool enable)
{
        jtag_verify = enable;
}

bool jtag_will_verify()
{
        return jtag_verify;
}

void jtag_set_verify_capture_ir(bool enable)
{
        jtag_verify_capture_ir = enable;
}

bool jtag_will_verify_capture_ir()
{
        return jtag_verify_capture_ir;
}

int jtag_power_dropout(int *dropout)
{
        return jtag->power_dropout(dropout);
}

int jtag_srst_asserted(int *srst_asserted)
{
        return jtag->srst_asserted(srst_asserted);
}

enum reset_types jtag_get_reset_config(void)
{
        return jtag_reset_config;
}
void jtag_set_reset_config(enum reset_types type)
{
        jtag_reset_config = type;
}

int jtag_get_trst(void)
{
        return jtag_trst;
}
int jtag_get_srst(void)
{
        return jtag_srst;
}

void jtag_set_nsrst_delay(unsigned delay)
{
        jtag_nsrst_delay = delay;
}
unsigned jtag_get_nsrst_delay(void)
{
        return jtag_nsrst_delay;
}
void jtag_set_ntrst_delay(unsigned delay)
{
        jtag_ntrst_delay = delay;
}
unsigned jtag_get_ntrst_delay(void)
{
        return jtag_ntrst_delay;
}