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

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007,2008 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   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 "bitbang.h"

/* project specific includes */
#include "log.h"
#include "types.h"
#include "jtag.h"
#include "configuration.h"

/* system includes */
#include <string.h>
#include <stdlib.h>
#include <unistd.h>


/**
 * Function bitbang_stableclocks
 * issues a number of clock cycles while staying in a stable state.
 * Because the TMS value required to stay in the RESET state is a 1, whereas
 * the TMS value required to stay in any of the other stable states is a 0,
 * this function checks the current stable state to decide on the value of TMS
 * to use.
 */
static void bitbang_stableclocks(int num_cycles);


bitbang_interface_t *bitbang_interface;

/* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
 *
 * Set this to 1 and str912 reset halt will fail.
 *
 * If someone can submit a patch with an explanation it will be greatly
 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
 * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
 * state". With hardware there is no such thing as *while* in a state. There
 * are only edges. So clk => 0 is in fact a very subtle state transition that
 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
 *
 * For "reset halt" the last thing that happens before srst is asserted
 * is that the breakpoint is set up. If DCLK is not wiggled one last
 * time before the reset, then the breakpoint is not set up and
 * "reset halt" will fail to halt.
 *
 */
#define CLOCK_IDLE() 0


/* The bitbang driver leaves the TCK 0 when in idle */
static void bitbang_end_state(tap_state_t state)
{
        if (tap_is_state_stable(state))
                tap_set_end_state(state);
        else
        {
                LOG_ERROR("BUG: %i is not a valid end state", state);
                exit(-1);
        }
}

static void bitbang_state_move(int skip)
{
        int i=0, tms=0;
        u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());

        for (i = skip; i < 7; i++)
        {
                tms = (tms_scan >> i) & 1;
                bitbang_interface->write(0, tms, 0);
                bitbang_interface->write(1, tms, 0);
        }
        bitbang_interface->write(CLOCK_IDLE(), tms, 0);

        tap_set_state(tap_get_end_state());
}

static void bitbang_path_move(pathmove_command_t *cmd)
{
        int num_states = cmd->num_states;
        int state_count;
        int tms = 0;

        state_count = 0;
        while (num_states)
        {
                if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
                {
                        tms = 0;
                }
                else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
                {
                        tms = 1;
                }
                else
                {
                        LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
                        exit(-1);
                }

                bitbang_interface->write(0, tms, 0);
                bitbang_interface->write(1, tms, 0);

                tap_set_state(cmd->path[state_count]);
                state_count++;
                num_states--;
        }

        bitbang_interface->write(CLOCK_IDLE(), tms, 0);

        tap_set_end_state(tap_get_state());
}

static void bitbang_runtest(int num_cycles)
{
        int i;

        tap_state_t saved_end_state = tap_get_end_state();

        /* only do a state_move when we're not already in IDLE */
        if (tap_get_state() != TAP_IDLE)
        {
                bitbang_end_state(TAP_IDLE);
                bitbang_state_move(0);
        }

        /* execute num_cycles */
        for (i = 0; i < num_cycles; i++)
        {
                bitbang_interface->write(0, 0, 0);
                bitbang_interface->write(1, 0, 0);
        }
        bitbang_interface->write(CLOCK_IDLE(), 0, 0);

        /* finish in end_state */
        bitbang_end_state(saved_end_state);
        if (tap_get_state() != tap_get_end_state())
                bitbang_state_move(0);
}


static void bitbang_stableclocks(int num_cycles)
{
        int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
        int i;

        /* send num_cycles clocks onto the cable */
        for (i = 0; i < num_cycles; i++)
        {
                bitbang_interface->write(1, tms, 0);
                bitbang_interface->write(0, tms, 0);
        }
}



static void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
{
        tap_state_t saved_end_state = tap_get_end_state();
        int bit_cnt;

        if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
        {
                if (ir_scan)
                        bitbang_end_state(TAP_IRSHIFT);
                else
                        bitbang_end_state(TAP_DRSHIFT);

                bitbang_state_move(0);
                bitbang_end_state(saved_end_state);
        }

        for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
        {
                int val=0;
                int tms=(bit_cnt==scan_size-1) ? 1 : 0;
                int tdi;
                int bytec=bit_cnt/8;
                int bcval=1<<(bit_cnt % 8);

                /* if we're just reading the scan, but don't care about the output
                 * default to outputting 'low', this also makes valgrind traces more readable,
                 * as it removes the dependency on an uninitialised value
                 */
                tdi=0;
                if ((type != SCAN_IN) && (buffer[bytec] & bcval))
                        tdi=1;

                bitbang_interface->write(0, tms, tdi);

                if (type!=SCAN_OUT)
                        val=bitbang_interface->read();

                bitbang_interface->write(1, tms, tdi);

                if (type != SCAN_OUT)
                {
                        if (val)
                                buffer[bytec] |= bcval;
                        else
                                buffer[bytec] &= ~bcval;
                }
        }

        if (tap_get_state() != tap_get_end_state())
        {
                /* we *KNOW* the above loop transitioned out of
                 * the shift state, so we skip the first state
                 * and move directly to the end state.
                 */
                bitbang_state_move(1);
        }
}

int bitbang_execute_queue(void)
{
        jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
        int scan_size;
        enum scan_type type;
        u8 *buffer;
        int retval;

        if (!bitbang_interface)
        {
                LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
                exit(-1);
        }

        /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
         * that wasn't handled by a caller-provided error handler
         */
        retval = ERROR_OK;

        if(bitbang_interface->blink)
                bitbang_interface->blink(1);

        while (cmd)
        {
                switch (cmd->type)
                {
                        case JTAG_END_STATE:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("end_state: %s", tap_state_name(cmd->cmd.end_state->end_state) );
#endif
                                if (cmd->cmd.end_state->end_state != TAP_INVALID)
                                        bitbang_end_state(cmd->cmd.end_state->end_state);
                                break;
                        case JTAG_RESET:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
#endif
                                if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
                                {
                                        tap_set_state(TAP_RESET);
                                }
                                bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
                                break;
                        case JTAG_RUNTEST:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
#endif
                                if (cmd->cmd.runtest->end_state != TAP_INVALID)
                                        bitbang_end_state(cmd->cmd.runtest->end_state);
                                bitbang_runtest(cmd->cmd.runtest->num_cycles);
                                break;

                        case JTAG_STABLECLOCKS:
                                /* this is only allowed while in a stable state.  A check for a stable
                                 * state was done in jtag_add_clocks()
                                 */
                                bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
                                break;

                        case JTAG_STATEMOVE:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
#endif
                                if (cmd->cmd.statemove->end_state != TAP_INVALID)
                                        bitbang_end_state(cmd->cmd.statemove->end_state);
                                bitbang_state_move(0);
                                break;
                        case JTAG_PATHMOVE:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
                                        tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
#endif
                                bitbang_path_move(cmd->cmd.pathmove);
                                break;
                        case JTAG_SCAN:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("%s scan end in %s",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
#endif
                                if (cmd->cmd.scan->end_state != TAP_INVALID)
                                        bitbang_end_state(cmd->cmd.scan->end_state);
                                scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
                                type = jtag_scan_type(cmd->cmd.scan);
                                bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
                                if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
                                        retval = ERROR_JTAG_QUEUE_FAILED;
                                if (buffer)
                                        free(buffer);
                                break;
                        case JTAG_SLEEP:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
#endif
                                jtag_sleep(cmd->cmd.sleep->us);
                                break;
                        default:
                                LOG_ERROR("BUG: unknown JTAG command type encountered");
                                exit(-1);
                }
                cmd = cmd->next;
        }
        if(bitbang_interface->blink)
                bitbang_interface->blink(0);

        return retval;
}