altera-jtag.c

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/*
 * altera-jtag.c
 *
 * altera FPGA driver
 *
 * Copyright (C) Altera Corporation 1998-2001
 * Copyright (C) 2010 NetUP Inc.
 * Copyright (C) 2010 Igor M. Liplianin <[email protected]>
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/delay.h>
#include <linux/firmware.h>
#include <linux/slab.h>
#include <misc/altera.h>
#include "altera-exprt.h"
#include "altera-jtag.h"

#define alt_jtag_io(a, b, c)\
        astate->config->jtag_io(astate->config->dev, a, b, c);

#define alt_malloc(a)   kzalloc(a, GFP_KERNEL);

/*
 * This structure shows, for each JTAG state, which state is reached after
 * a single TCK clock cycle with TMS high or TMS low, respectively.  This
 * describes all possible state transitions in the JTAG state machine.
 */
struct altera_jtag_machine {
    enum altera_jtag_state tms_high;
    enum altera_jtag_state tms_low;
};

static const struct altera_jtag_machine altera_transitions[] = {
    /* RESET     */ { RESET,    IDLE },
    /* IDLE      */ { DRSELECT, IDLE },
    /* DRSELECT  */ { IRSELECT, DRCAPTURE },
    /* DRCAPTURE */ { DREXIT1,  DRSHIFT },
    /* DRSHIFT   */ { DREXIT1,  DRSHIFT },
    /* DREXIT1   */ { DRUPDATE, DRPAUSE },
    /* DRPAUSE   */ { DREXIT2,  DRPAUSE },
    /* DREXIT2   */ { DRUPDATE, DRSHIFT },
    /* DRUPDATE  */ { DRSELECT, IDLE },
    /* IRSELECT  */ { RESET,    IRCAPTURE },
    /* IRCAPTURE */ { IREXIT1,  IRSHIFT },
    /* IRSHIFT   */ { IREXIT1,  IRSHIFT },
    /* IREXIT1   */ { IRUPDATE, IRPAUSE },
    /* IRPAUSE   */ { IREXIT2,  IRPAUSE },
    /* IREXIT2   */ { IRUPDATE, IRSHIFT },
    /* IRUPDATE  */ { DRSELECT, IDLE }
};

/*
 * This table contains the TMS value to be used to take the NEXT STEP on
 * the path to the desired state.  The array index is the current state,
 * and the bit position is the desired endstate.  To find out which state
 * is used as the intermediate state, look up the TMS value in the
 * altera_transitions[] table.
 */
static const u16 altera_jtag_path_map[16] = {
    /* RST  RTI SDRS    CDR SDR E1DR    PDR E2DR */
    0x0001, 0xFFFD, 0xFE01, 0xFFE7, 0xFFEF, 0xFF0F, 0xFFBF, 0xFFFF,
    /* UDR  SIRS    CIR SIR E1IR    PIR E2IR    UIR */
    0xFEFD, 0x0001, 0xF3FF, 0xF7FF, 0x87FF, 0xDFFF, 0xFFFF, 0x7FFD
};

/* Flag bits for alt_jtag_io() function */
#define TMS_HIGH   1
#define TMS_LOW    0
#define TDI_HIGH   1
#define TDI_LOW    0
#define READ_TDO   1
#define IGNORE_TDO 0

int altera_jinit(struct altera_state *astate)
{
    struct altera_jtag *js = &astate->js;

    /* initial JTAG state is unknown */
    js->jtag_state = ILLEGAL_JTAG_STATE;

    /* initialize to default state */
    js->drstop_state = IDLE;
    js->irstop_state = IDLE;
    js->dr_pre  = 0;
    js->dr_post = 0;
    js->ir_pre  = 0;
    js->ir_post = 0;
    js->dr_length    = 0;
    js->ir_length    = 0;

    js->dr_pre_data  = NULL;
    js->dr_post_data = NULL;
    js->ir_pre_data  = NULL;
    js->ir_post_data = NULL;
    js->dr_buffer    = NULL;
    js->ir_buffer    = NULL;

    return 0;
}

int altera_set_drstop(struct altera_jtag *js, enum altera_jtag_state state)
{
    js->drstop_state = state;

    return 0;
}

int altera_set_irstop(struct altera_jtag *js, enum altera_jtag_state state)
{
    js->irstop_state = state;

    return 0;
}

int altera_set_dr_pre(struct altera_jtag *js,
                u32 count, u32 start_index,
                u8 *preamble_data)
{
    int status = 0;
    u32 i;
    u32 j;

    if (count > js->dr_pre) {
        kfree(js->dr_pre_data);
        js->dr_pre_data = (u8 *)alt_malloc((count + 7) >> 3);
        if (js->dr_pre_data == NULL)
            status = -ENOMEM;
        else
            js->dr_pre = count;
    } else
        js->dr_pre = count;

    if (status == 0) {
        for (i = 0; i < count; ++i) {
            j = i + start_index;

            if (preamble_data == NULL)
                js->dr_pre_data[i >> 3] |= (1 << (i & 7));
            else {
                if (preamble_data[j >> 3] & (1 << (j & 7)))
                    js->dr_pre_data[i >> 3] |=
                            (1 << (i & 7));
                else
                    js->dr_pre_data[i >> 3] &=
                            ~(u32)(1 << (i & 7));

            }
        }
    }

    return status;
}

int altera_set_ir_pre(struct altera_jtag *js, u32 count, u32 start_index,
                            u8 *preamble_data)
{
    int status = 0;
    u32 i;
    u32 j;

    if (count > js->ir_pre) {
        kfree(js->ir_pre_data);
        js->ir_pre_data = (u8 *)alt_malloc((count + 7) >> 3);
        if (js->ir_pre_data == NULL)
            status = -ENOMEM;
        else
            js->ir_pre = count;

    } else
        js->ir_pre = count;

    if (status == 0) {
        for (i = 0; i < count; ++i) {
            j = i + start_index;
            if (preamble_data == NULL)
                js->ir_pre_data[i >> 3] |= (1 << (i & 7));
            else {
                if (preamble_data[j >> 3] & (1 << (j & 7)))
                    js->ir_pre_data[i >> 3] |=
                            (1 << (i & 7));
                else
                    js->ir_pre_data[i >> 3] &=
                            ~(u32)(1 << (i & 7));

            }
        }
    }

    return status;
}

int altera_set_dr_post(struct altera_jtag *js, u32 count, u32 start_index,
                        u8 *postamble_data)
{
    int status = 0;
    u32 i;
    u32 j;

    if (count > js->dr_post) {
        kfree(js->dr_post_data);
        js->dr_post_data = (u8 *)alt_malloc((count + 7) >> 3);

        if (js->dr_post_data == NULL)
            status = -ENOMEM;
        else
            js->dr_post = count;

    } else
        js->dr_post = count;

    if (status == 0) {
        for (i = 0; i < count; ++i) {
            j = i + start_index;

            if (postamble_data == NULL)
                js->dr_post_data[i >> 3] |= (1 << (i & 7));
            else {
                if (postamble_data[j >> 3] & (1 << (j & 7)))
                    js->dr_post_data[i >> 3] |=
                                (1 << (i & 7));
                else
                    js->dr_post_data[i >> 3] &=
                        ~(u32)(1 << (i & 7));

            }
        }
    }

    return status;
}

int altera_set_ir_post(struct altera_jtag *js, u32 count, u32 start_index,
                        u8 *postamble_data)
{
    int status = 0;
    u32 i;
    u32 j;

    if (count > js->ir_post) {
        kfree(js->ir_post_data);
        js->ir_post_data = (u8 *)alt_malloc((count + 7) >> 3);
        if (js->ir_post_data == NULL)
            status = -ENOMEM;
        else
            js->ir_post = count;

    } else
        js->ir_post = count;

    if (status != 0)
        return status;

    for (i = 0; i < count; ++i) {
        j = i + start_index;

        if (postamble_data == NULL)
            js->ir_post_data[i >> 3] |= (1 << (i & 7));
        else {
            if (postamble_data[j >> 3] & (1 << (j & 7)))
                js->ir_post_data[i >> 3] |= (1 << (i & 7));
            else
                js->ir_post_data[i >> 3] &=
                    ~(u32)(1 << (i & 7));

        }
    }

    return status;
}

static void altera_jreset_idle(struct altera_state *astate)
{
    struct altera_jtag *js = &astate->js;
    int i;
    /* Go to Test Logic Reset (no matter what the starting state may be) */
    for (i = 0; i < 5; ++i)
        alt_jtag_io(TMS_HIGH, TDI_LOW, IGNORE_TDO);

    /* Now step to Run Test / Idle */
    alt_jtag_io(TMS_LOW, TDI_LOW, IGNORE_TDO);
    js->jtag_state = IDLE;
}

int altera_goto_jstate(struct altera_state *astate,
                    enum altera_jtag_state state)
{
    struct altera_jtag *js = &astate->js;
    int tms;
    int count = 0;
    int status = 0;

    if (js->jtag_state == ILLEGAL_JTAG_STATE)
        /* initialize JTAG chain to known state */
        altera_jreset_idle(astate);

    if (js->jtag_state == state) {
        /*
         * We are already in the desired state.
         * If it is a stable state, loop here.
         * Otherwise do nothing (no clock cycles).
         */
        if ((state == IDLE) || (state == DRSHIFT) ||
            (state == DRPAUSE) || (state == IRSHIFT) ||
                (state == IRPAUSE)) {
            alt_jtag_io(TMS_LOW, TDI_LOW, IGNORE_TDO);
        } else if (state == RESET)
            alt_jtag_io(TMS_HIGH, TDI_LOW, IGNORE_TDO);

    } else {
        while ((js->jtag_state != state) && (count < 9)) {
            /* Get TMS value to take a step toward desired state */
            tms = (altera_jtag_path_map[js->jtag_state] &
                            (1 << state))
                            ? TMS_HIGH : TMS_LOW;

            /* Take a step */
            alt_jtag_io(tms, TDI_LOW, IGNORE_TDO);

            if (tms)
                js->jtag_state =
                    altera_transitions[js->jtag_state].tms_high;
            else
                js->jtag_state =
                    altera_transitions[js->jtag_state].tms_low;

            ++count;
        }
    }

    if (js->jtag_state != state)
        status = -EREMOTEIO;

    return status;
}

int altera_wait_cycles(struct altera_state *astate,
                    s32 cycles,
                    enum altera_jtag_state wait_state)
{
    struct altera_jtag *js = &astate->js;
    int tms;
    s32 count;
    int status = 0;

    if (js->jtag_state != wait_state)
        status = altera_goto_jstate(astate, wait_state);

    if (status == 0) {
        /*
         * Set TMS high to loop in RESET state
         * Set TMS low to loop in any other stable state
         */
        tms = (wait_state == RESET) ? TMS_HIGH : TMS_LOW;

        for (count = 0L; count < cycles; count++)
            alt_jtag_io(tms, TDI_LOW, IGNORE_TDO);

    }

    return status;
}

int altera_wait_msecs(struct altera_state *astate,
            s32 microseconds, enum altera_jtag_state wait_state)
/*
 * Causes JTAG hardware to sit in the specified stable
 * state for the specified duration of real time.  If
 * no JTAG operations have been performed yet, then only
 * a delay is performed.  This permits the WAIT USECS
 * statement to be used in VECTOR programs without causing
 * any JTAG operations.
 * Returns 0 for success, else appropriate error code.
 */
{
    struct altera_jtag *js = &astate->js;
    int status = 0;

    if ((js->jtag_state != ILLEGAL_JTAG_STATE) &&
        (js->jtag_state != wait_state))
        status = altera_goto_jstate(astate, wait_state);

    if (status == 0)
        /* Wait for specified time interval */
        udelay(microseconds);

    return status;
}

static void altera_concatenate_data(u8 *buffer,
                u8 *preamble_data,
                u32 preamble_count,
                u8 *target_data,
                u32 start_index,
                u32 target_count,
                u8 *postamble_data,
                u32 postamble_count)
/*
 * Copies preamble data, target data, and postamble data
 * into one buffer for IR or DR scans.
 */
{
    u32 i, j, k;

    for (i = 0L; i < preamble_count; ++i) {
        if (preamble_data[i >> 3L] & (1L << (i & 7L)))
            buffer[i >> 3L] |= (1L << (i & 7L));
        else
            buffer[i >> 3L] &= ~(u32)(1L << (i & 7L));

    }

    j = start_index;
    k = preamble_count + target_count;
    for (; i < k; ++i, ++j) {
        if (target_data[j >> 3L] & (1L << (j & 7L)))
            buffer[i >> 3L] |= (1L << (i & 7L));
        else
            buffer[i >> 3L] &= ~(u32)(1L << (i & 7L));

    }

    j = 0L;
    k = preamble_count + target_count + postamble_count;
    for (; i < k; ++i, ++j) {
        if (postamble_data[j >> 3L] & (1L << (j & 7L)))
            buffer[i >> 3L] |= (1L << (i & 7L));
        else
            buffer[i >> 3L] &= ~(u32)(1L << (i & 7L));

    }
}

static int alt_jtag_drscan(struct altera_state *astate,
            int start_state,
            int count,
            u8 *tdi,
            u8 *tdo)
{
    int i = 0;
    int tdo_bit = 0;
    int status = 1;

    /* First go to DRSHIFT state */
    switch (start_state) {
    case 0:                     /* IDLE */
        alt_jtag_io(1, 0, 0);   /* DRSELECT */
        alt_jtag_io(0, 0, 0);   /* DRCAPTURE */
        alt_jtag_io(0, 0, 0);   /* DRSHIFT */
        break;

    case 1:                     /* DRPAUSE */
        alt_jtag_io(1, 0, 0);   /* DREXIT2 */
        alt_jtag_io(1, 0, 0);   /* DRUPDATE */
        alt_jtag_io(1, 0, 0);   /* DRSELECT */
        alt_jtag_io(0, 0, 0);   /* DRCAPTURE */
        alt_jtag_io(0, 0, 0);   /* DRSHIFT */
        break;

    case 2:                     /* IRPAUSE */
        alt_jtag_io(1, 0, 0);   /* IREXIT2 */
        alt_jtag_io(1, 0, 0);   /* IRUPDATE */
        alt_jtag_io(1, 0, 0);   /* DRSELECT */
        alt_jtag_io(0, 0, 0);   /* DRCAPTURE */
        alt_jtag_io(0, 0, 0);   /* DRSHIFT */
        break;

    default:
        status = 0;
    }

    if (status) {
        /* loop in the SHIFT-DR state */
        for (i = 0; i < count; i++) {
            tdo_bit = alt_jtag_io(
                    (i == count - 1),
                    tdi[i >> 3] & (1 << (i & 7)),
                    (tdo != NULL));

            if (tdo != NULL) {
                if (tdo_bit)
                    tdo[i >> 3] |= (1 << (i & 7));
                else
                    tdo[i >> 3] &= ~(u32)(1 << (i & 7));

            }
        }

        alt_jtag_io(0, 0, 0);   /* DRPAUSE */
    }

    return status;
}

static int alt_jtag_irscan(struct altera_state *astate,
            int start_state,
            int count,
            u8 *tdi,
            u8 *tdo)
{
    int i = 0;
    int tdo_bit = 0;
    int status = 1;

    /* First go to IRSHIFT state */
    switch (start_state) {
    case 0:                     /* IDLE */
        alt_jtag_io(1, 0, 0);   /* DRSELECT */
        alt_jtag_io(1, 0, 0);   /* IRSELECT */
        alt_jtag_io(0, 0, 0);   /* IRCAPTURE */
        alt_jtag_io(0, 0, 0);   /* IRSHIFT */
        break;

    case 1:                     /* DRPAUSE */
        alt_jtag_io(1, 0, 0);   /* DREXIT2 */
        alt_jtag_io(1, 0, 0);   /* DRUPDATE */
        alt_jtag_io(1, 0, 0);   /* DRSELECT */
        alt_jtag_io(1, 0, 0);   /* IRSELECT */
        alt_jtag_io(0, 0, 0);   /* IRCAPTURE */
        alt_jtag_io(0, 0, 0);   /* IRSHIFT */
        break;

    case 2:                     /* IRPAUSE */
        alt_jtag_io(1, 0, 0);   /* IREXIT2 */
        alt_jtag_io(1, 0, 0);   /* IRUPDATE */
        alt_jtag_io(1, 0, 0);   /* DRSELECT */
        alt_jtag_io(1, 0, 0);   /* IRSELECT */
        alt_jtag_io(0, 0, 0);   /* IRCAPTURE */
        alt_jtag_io(0, 0, 0);   /* IRSHIFT */
        break;

    default:
        status = 0;
    }

    if (status) {
        /* loop in the SHIFT-IR state */
        for (i = 0; i < count; i++) {
            tdo_bit = alt_jtag_io(
                      (i == count - 1),
                      tdi[i >> 3] & (1 << (i & 7)),
                      (tdo != NULL));
            if (tdo != NULL) {
                if (tdo_bit)
                    tdo[i >> 3] |= (1 << (i & 7));
                else
                    tdo[i >> 3] &= ~(u32)(1 << (i & 7));

            }
        }

        alt_jtag_io(0, 0, 0);   /* IRPAUSE */
    }

    return status;
}

static void altera_extract_target_data(u8 *buffer,
                u8 *target_data,
                u32 start_index,
                u32 preamble_count,
                u32 target_count)
/*
 * Copies target data from scan buffer, filtering out
 * preamble and postamble data.
 */
{
    u32 i;
    u32 j;
    u32 k;

    j = preamble_count;
    k = start_index + target_count;
    for (i = start_index; i < k; ++i, ++j) {
        if (buffer[j >> 3] & (1 << (j & 7)))
            target_data[i >> 3] |= (1 << (i & 7));
        else
            target_data[i >> 3] &= ~(u32)(1 << (i & 7));

    }
}

int altera_irscan(struct altera_state *astate,
                u32 count,
                u8 *tdi_data,
                u32 start_index)
/* Shifts data into instruction register */
{
    struct altera_jtag *js = &astate->js;
    int start_code = 0;
    u32 alloc_chars = 0;
    u32 shift_count = js->ir_pre + count + js->ir_post;
    int status = 0;
    enum altera_jtag_state start_state = ILLEGAL_JTAG_STATE;

    switch (js->jtag_state) {
    case ILLEGAL_JTAG_STATE:
    case RESET:
    case IDLE:
        start_code = 0;
        start_state = IDLE;
        break;

    case DRSELECT:
    case DRCAPTURE:
    case DRSHIFT:
    case DREXIT1:
    case DRPAUSE:
    case DREXIT2:
    case DRUPDATE:
        start_code = 1;
        start_state = DRPAUSE;
        break;

    case IRSELECT:
    case IRCAPTURE:
    case IRSHIFT:
    case IREXIT1:
    case IRPAUSE:
    case IREXIT2:
    case IRUPDATE:
        start_code = 2;
        start_state = IRPAUSE;
        break;

    default:
        status = -EREMOTEIO;
        break;
    }

    if (status == 0)
        if (js->jtag_state != start_state)
            status = altera_goto_jstate(astate, start_state);

    if (status == 0) {
        if (shift_count > js->ir_length) {
            alloc_chars = (shift_count + 7) >> 3;
            kfree(js->ir_buffer);
            js->ir_buffer = (u8 *)alt_malloc(alloc_chars);
            if (js->ir_buffer == NULL)
                status = -ENOMEM;
            else
                js->ir_length = alloc_chars * 8;

        }
    }

    if (status == 0) {
        /*
         * Copy preamble data, IR data,
         * and postamble data into a buffer
         */
        altera_concatenate_data(js->ir_buffer,
                    js->ir_pre_data,
                    js->ir_pre,
                    tdi_data,
                    start_index,
                    count,
                    js->ir_post_data,
                    js->ir_post);
        /* Do the IRSCAN */
        alt_jtag_irscan(astate,
                start_code,
                shift_count,
                js->ir_buffer,
                NULL);

        /* alt_jtag_irscan() always ends in IRPAUSE state */
        js->jtag_state = IRPAUSE;
    }

    if (status == 0)
        if (js->irstop_state != IRPAUSE)
            status = altera_goto_jstate(astate, js->irstop_state);


    return status;
}

int altera_swap_ir(struct altera_state *astate,
                u32 count,
                u8 *in_data,
                u32 in_index,
                u8 *out_data,
                u32 out_index)
/* Shifts data into instruction register, capturing output data */
{
    struct altera_jtag *js = &astate->js;
    int start_code = 0;
    u32 alloc_chars = 0;
    u32 shift_count = js->ir_pre + count + js->ir_post;
    int status = 0;
    enum altera_jtag_state start_state = ILLEGAL_JTAG_STATE;

    switch (js->jtag_state) {
    case ILLEGAL_JTAG_STATE:
    case RESET:
    case IDLE:
        start_code = 0;
        start_state = IDLE;
        break;

    case DRSELECT:
    case DRCAPTURE:
    case DRSHIFT:
    case DREXIT1:
    case DRPAUSE:
    case DREXIT2:
    case DRUPDATE:
        start_code = 1;
        start_state = DRPAUSE;
        break;

    case IRSELECT:
    case IRCAPTURE:
    case IRSHIFT:
    case IREXIT1:
    case IRPAUSE:
    case IREXIT2:
    case IRUPDATE:
        start_code = 2;
        start_state = IRPAUSE;
        break;

    default:
        status = -EREMOTEIO;
        break;
    }

    if (status == 0)
        if (js->jtag_state != start_state)
            status = altera_goto_jstate(astate, start_state);

    if (status == 0) {
        if (shift_count > js->ir_length) {
            alloc_chars = (shift_count + 7) >> 3;
            kfree(js->ir_buffer);
            js->ir_buffer = (u8 *)alt_malloc(alloc_chars);
            if (js->ir_buffer == NULL)
                status = -ENOMEM;
            else
                js->ir_length = alloc_chars * 8;

        }
    }

    if (status == 0) {
        /*
         * Copy preamble data, IR data,
         * and postamble data into a buffer
         */
        altera_concatenate_data(js->ir_buffer,
                    js->ir_pre_data,
                    js->ir_pre,
                    in_data,
                    in_index,
                    count,
                    js->ir_post_data,
                    js->ir_post);

        /* Do the IRSCAN */
        alt_jtag_irscan(astate,
                start_code,
                shift_count,
                js->ir_buffer,
                js->ir_buffer);

        /* alt_jtag_irscan() always ends in IRPAUSE state */
        js->jtag_state = IRPAUSE;
    }

    if (status == 0)
        if (js->irstop_state != IRPAUSE)
            status = altera_goto_jstate(astate, js->irstop_state);


    if (status == 0)
        /* Now extract the returned data from the buffer */
        altera_extract_target_data(js->ir_buffer,
                    out_data, out_index,
                    js->ir_pre, count);

    return status;
}

int altera_drscan(struct altera_state *astate,
                u32 count,
                u8 *tdi_data,
                u32 start_index)
/* Shifts data into data register (ignoring output data) */
{
    struct altera_jtag *js = &astate->js;
    int start_code = 0;
    u32 alloc_chars = 0;
    u32 shift_count = js->dr_pre + count + js->dr_post;
    int status = 0;
    enum altera_jtag_state start_state = ILLEGAL_JTAG_STATE;

    switch (js->jtag_state) {
    case ILLEGAL_JTAG_STATE:
    case RESET:
    case IDLE:
        start_code = 0;
        start_state = IDLE;
        break;

    case DRSELECT:
    case DRCAPTURE:
    case DRSHIFT:
    case DREXIT1:
    case DRPAUSE:
    case DREXIT2:
    case DRUPDATE:
        start_code = 1;
        start_state = DRPAUSE;
        break;

    case IRSELECT:
    case IRCAPTURE:
    case IRSHIFT:
    case IREXIT1:
    case IRPAUSE:
    case IREXIT2:
    case IRUPDATE:
        start_code = 2;
        start_state = IRPAUSE;
        break;

    default:
        status = -EREMOTEIO;
        break;
    }

    if (status == 0)
        if (js->jtag_state != start_state)
            status = altera_goto_jstate(astate, start_state);

    if (status == 0) {
        if (shift_count > js->dr_length) {
            alloc_chars = (shift_count + 7) >> 3;
            kfree(js->dr_buffer);
            js->dr_buffer = (u8 *)alt_malloc(alloc_chars);
            if (js->dr_buffer == NULL)
                status = -ENOMEM;
            else
                js->dr_length = alloc_chars * 8;

        }
    }

    if (status == 0) {
        /*
         * Copy preamble data, DR data,
         * and postamble data into a buffer
         */
        altera_concatenate_data(js->dr_buffer,
                    js->dr_pre_data,
                    js->dr_pre,
                    tdi_data,
                    start_index,
                    count,
                    js->dr_post_data,
                    js->dr_post);
        /* Do the DRSCAN */
        alt_jtag_drscan(astate, start_code, shift_count,
                js->dr_buffer, NULL);
        /* alt_jtag_drscan() always ends in DRPAUSE state */
        js->jtag_state = DRPAUSE;
    }

    if (status == 0)
        if (js->drstop_state != DRPAUSE)
            status = altera_goto_jstate(astate, js->drstop_state);

    return status;
}

int altera_swap_dr(struct altera_state *astate, u32 count,
                u8 *in_data, u32 in_index,
                u8 *out_data, u32 out_index)
/* Shifts data into data register, capturing output data */
{
    struct altera_jtag *js = &astate->js;
    int start_code = 0;
    u32 alloc_chars = 0;
    u32 shift_count = js->dr_pre + count + js->dr_post;
    int status = 0;
    enum altera_jtag_state start_state = ILLEGAL_JTAG_STATE;

    switch (js->jtag_state) {
    case ILLEGAL_JTAG_STATE:
    case RESET:
    case IDLE:
        start_code = 0;
        start_state = IDLE;
        break;

    case DRSELECT:
    case DRCAPTURE:
    case DRSHIFT:
    case DREXIT1:
    case DRPAUSE:
    case DREXIT2:
    case DRUPDATE:
        start_code = 1;
        start_state = DRPAUSE;
        break;

    case IRSELECT:
    case IRCAPTURE:
    case IRSHIFT:
    case IREXIT1:
    case IRPAUSE:
    case IREXIT2:
    case IRUPDATE:
        start_code = 2;
        start_state = IRPAUSE;
        break;

    default:
        status = -EREMOTEIO;
        break;
    }

    if (status == 0)
        if (js->jtag_state != start_state)
            status = altera_goto_jstate(astate, start_state);

    if (status == 0) {
        if (shift_count > js->dr_length) {
            alloc_chars = (shift_count + 7) >> 3;
            kfree(js->dr_buffer);
            js->dr_buffer = (u8 *)alt_malloc(alloc_chars);

            if (js->dr_buffer == NULL)
                status = -ENOMEM;
            else
                js->dr_length = alloc_chars * 8;

        }
    }

    if (status == 0) {
        /*
         * Copy preamble data, DR data,
         * and postamble data into a buffer
         */
        altera_concatenate_data(js->dr_buffer,
                js->dr_pre_data,
                js->dr_pre,
                in_data,
                in_index,
                count,
                js->dr_post_data,
                js->dr_post);

        /* Do the DRSCAN */
        alt_jtag_drscan(astate,
                start_code,
                shift_count,
                js->dr_buffer,
                js->dr_buffer);

        /* alt_jtag_drscan() always ends in DRPAUSE state */
        js->jtag_state = DRPAUSE;
    }

    if (status == 0)
        if (js->drstop_state != DRPAUSE)
            status = altera_goto_jstate(astate, js->drstop_state);

    if (status == 0)
        /* Now extract the returned data from the buffer */
        altera_extract_target_data(js->dr_buffer,
                    out_data,
                    out_index,
                    js->dr_pre,
                    count);

    return status;
}

void altera_free_buffers(struct altera_state *astate)
{
    struct altera_jtag *js = &astate->js;
    /* If the JTAG interface was used, reset it to TLR */
    if (js->jtag_state != ILLEGAL_JTAG_STATE)
        altera_jreset_idle(astate);

    kfree(js->dr_pre_data);
    js->dr_pre_data = NULL;

    kfree(js->dr_post_data);
    js->dr_post_data = NULL;

    kfree(js->dr_buffer);
    js->dr_buffer = NULL;

    kfree(js->ir_pre_data);
    js->ir_pre_data = NULL;

    kfree(js->ir_post_data);
    js->ir_post_data = NULL;

    kfree(js->ir_buffer);
    js->ir_buffer = NULL;
}