ADIv5: use right ID for Cortex-M3 ETM

[openocd.git] / src / target / arm_adi_v5.c

/***************************************************************************
 *   Copyright (C) 2006 by Magnus Lundin                                   *
 *   lundin@mlu.mine.nu                                                    *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   Copyright (C) 2009 by Oyvind Harboe                                   *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   Copyright (C) 2009-2010 by David Brownell                             *
 *                                                                         *
 *   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.             *
 ***************************************************************************/

/**
 * @file
 * This file implements support for the ARM Debug Interface version 5 (ADIv5)
 * debugging architecture.  Compared with previous versions, this includes
 * a low pin-count Serial Wire Debug (SWD) alternative to JTAG for message
 * transport, and focusses on memory mapped resources as defined by the
 * CoreSight architecture.
 *
 * A key concept in ADIv5 is the Debug Access Port, or DAP.  A DAP has two
 * basic components:  a Debug Port (DP) transporting messages to and from a
 * debugger, and an Access Port (AP) accessing resources.  Three types of DP
 * are defined.  One uses only JTAG for communication, and is called JTAG-DP.
 * One uses only SWD for communication, and is called SW-DP.  The third can
 * use either SWD or JTAG, and is called SWJ-DP.  The most common type of AP
 * is used to access memory mapped resources and is called a MEM-AP.  Also a
 * JTAG-AP is also defined, bridging to JTAG resources; those are uncommon.
 *
 * This programming interface allows DAP pipelined operations through a
 * transaction queue.  This primarily affects AP operations (such as using
 * a MEM-AP to access memory or registers).  If the current transaction has
 * not finished by the time the next one must begin, and the ORUNDETECT bit
 * is set in the DP_CTRL_STAT register, the SSTICKYORUN status is set and
 * further AP operations will fail.  There are two basic methods to avoid
 * such overrun errors.  One involves polling for status instead of using
 * transaction piplining.  The other involves adding delays to ensure the
 * AP has enough time to complete one operation before starting the next
 * one.  (For JTAG these delays are controlled by memaccess_tck.)
 */

/*
 * Relevant specifications from ARM include:
 *
 * ARM(tm) Debug Interface v5 Architecture Specification    ARM IHI 0031A
 * CoreSight(tm) v1.0 Architecture Specification            ARM IHI 0029B
 *
 * CoreSight(tm) DAP-Lite TRM, ARM DDI 0316D
 * Cortex-M3(tm) TRM, ARM DDI 0337G
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "arm_adi_v5.h"
#include <helper/time_support.h>


/* ARM ADI Specification requires at least 10 bits used for TAR autoincrement  */

/*
        uint32_t tar_block_size(uint32_t address)
        Return the largest block starting at address that does not cross a tar block size alignment boundary
*/
static uint32_t max_tar_block_size(uint32_t tar_autoincr_block, uint32_t address)
{
        return (tar_autoincr_block - ((tar_autoincr_block - 1) & address)) >> 2;
}

/***************************************************************************
 *                                                                         *
 * DPACC and APACC scanchain access through JTAG-DP                        *
 *                                                                         *
***************************************************************************/

/**
 * Scan DPACC or APACC using target ordered uint8_t buffers.  No endianness
 * conversions are performed.  See section 4.4.3 of the ADIv5 spec, which
 * discusses operations which access these registers.
 *
 * Note that only one scan is performed.  If RnW is set, a separate scan
 * will be needed to collect the data which was read; the "invalue" collects
 * the posted result of a preceding operation, not the current one.
 *
 * @param swjdp the DAP
 * @param instr JTAG_DP_APACC (AP access) or JTAG_DP_DPACC (DP access)
 * @param reg_addr two significant bits; A[3:2]; for APACC access, the
 *      SELECT register has more addressing bits.
 * @param RnW false iff outvalue will be written to the DP or AP
 * @param outvalue points to a 32-bit (little-endian) integer
 * @param invalue NULL, or points to a 32-bit (little-endian) integer
 * @param ack points to where the three bit JTAG_ACK_* code will be stored
 */
static int adi_jtag_dp_scan(struct swjdp_common *swjdp,
                uint8_t instr, uint8_t reg_addr, uint8_t RnW,
                uint8_t *outvalue, uint8_t *invalue, uint8_t *ack)
{
        struct arm_jtag *jtag_info = swjdp->jtag_info;
        struct scan_field fields[2];
        uint8_t out_addr_buf;

        jtag_set_end_state(TAP_IDLE);
        arm_jtag_set_instr(jtag_info, instr, NULL);

        /* Scan out a read or write operation using some DP or AP register.
         * For APACC access with any sticky error flag set, this is discarded.
         */
        fields[0].tap = jtag_info->tap;
        fields[0].num_bits = 3;
        buf_set_u32(&out_addr_buf, 0, 3, ((reg_addr >> 1) & 0x6) | (RnW & 0x1));
        fields[0].out_value = &out_addr_buf;
        fields[0].in_value = ack;

        /* NOTE: if we receive JTAG_ACK_WAIT, the previous operation did not
         * complete; data we write is discarded, data we read is unpredictable.
         * When overrun detect is active, STICKYORUN is set.
         */

        fields[1].tap = jtag_info->tap;
        fields[1].num_bits = 32;
        fields[1].out_value = outvalue;
        fields[1].in_value = invalue;

        jtag_add_dr_scan(2, fields, jtag_get_end_state());

        /* Add specified number of tck clocks after starting memory bus
         * access, giving the hardware time to complete the access.
         * They provide more time for the (MEM) AP to complete the read ...
         * See "Minimum Response Time" for JTAG-DP, in the ADIv5 spec.
         */
        if ((instr == JTAG_DP_APACC)
                        && ((reg_addr == AP_REG_DRW)
                                || ((reg_addr & 0xF0) == AP_REG_BD0))
                        && (swjdp->memaccess_tck != 0))
                jtag_add_runtest(swjdp->memaccess_tck,
                                jtag_set_end_state(TAP_IDLE));

        return jtag_get_error();
}

/**
 * Scan DPACC or APACC out and in from host ordered uint32_t buffers.
 * This is exactly like adi_jtag_dp_scan(), except that endianness
 * conversions are performed (so the types of invalue and outvalue
 * must be different).
 */
static int adi_jtag_dp_scan_u32(struct swjdp_common *swjdp,
                uint8_t instr, uint8_t reg_addr, uint8_t RnW,
                uint32_t outvalue, uint32_t *invalue, uint8_t *ack)
{
        uint8_t out_value_buf[4];
        int retval;

        buf_set_u32(out_value_buf, 0, 32, outvalue);

        retval = adi_jtag_dp_scan(swjdp, instr, reg_addr, RnW,
                        out_value_buf, (uint8_t *)invalue, ack);
        if (retval != ERROR_OK)
                return retval;

        if (invalue)
                jtag_add_callback(arm_le_to_h_u32,
                                (jtag_callback_data_t) invalue);

        return retval;
}

/**
 * Utility to write AP registers.
 */
static inline int adi_jtag_ap_write_check(struct swjdp_common *dap,
                uint8_t reg_addr, uint8_t *outvalue)
{
        return adi_jtag_dp_scan(dap, JTAG_DP_APACC, reg_addr, DPAP_WRITE,
                        outvalue, NULL, NULL);
}

static int adi_jtag_scan_inout_check_u32(struct swjdp_common *swjdp,
                uint8_t instr, uint8_t reg_addr, uint8_t RnW,
                uint32_t outvalue, uint32_t *invalue)
{
        int retval;

        /* Issue the read or write */
        retval = adi_jtag_dp_scan_u32(swjdp, instr, reg_addr,
                        RnW, outvalue, NULL, NULL);
        if (retval != ERROR_OK)
                return retval;

        /* For reads,  collect posted value; RDBUFF has no other effect.
         * Assumes read gets acked with OK/FAULT, and CTRL_STAT says "OK".
         */
        if ((RnW == DPAP_READ) && (invalue != NULL))
                retval = adi_jtag_dp_scan_u32(swjdp, JTAG_DP_DPACC,
                                DP_RDBUFF, DPAP_READ, 0, invalue, &swjdp->ack);
        return retval;
}

int jtagdp_transaction_endcheck(struct swjdp_common *swjdp)
{
        int retval;
        uint32_t ctrlstat;

        /* too expensive to call keep_alive() here */

#if 0
        /* Danger!!!! BROKEN!!!! */
        adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat);
        /* Danger!!!! BROKEN!!!! Why will jtag_execute_queue() fail here????
        R956 introduced the check on return value here and now Michael Schwingen reports
        that this code no longer works....

        https://lists.berlios.de/pipermail/openocd-development/2008-September/003107.html
        */
        if ((retval = jtag_execute_queue()) != ERROR_OK)
        {
                LOG_ERROR("BUG: Why does this fail the first time????");
        }
        /* Why??? second time it works??? */
#endif

        /* Post CTRL/STAT read; discard any previous posted read value
         * but collect its ACK status.
         */
        adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat);
        if ((retval = jtag_execute_queue()) != ERROR_OK)
                return retval;

        swjdp->ack = swjdp->ack & 0x7;

        /* common code path avoids calling timeval_ms() */
        if (swjdp->ack != JTAG_ACK_OK_FAULT)
        {
                long long then = timeval_ms();

                while (swjdp->ack != JTAG_ACK_OK_FAULT)
                {
                        if (swjdp->ack == JTAG_ACK_WAIT)
                        {
                                if ((timeval_ms()-then) > 1000)
                                {
                                        /* NOTE:  this would be a good spot
                                         * to use JTAG_DP_ABORT.
                                         */
                                        LOG_WARNING("Timeout (1000ms) waiting "
                                                "for ACK=OK/FAULT "
                                                "in JTAG-DP transaction");
                                        return ERROR_JTAG_DEVICE_ERROR;
                                }
                        }
                        else
                        {
                                LOG_WARNING("Invalid ACK %#x "
                                                "in JTAG-DP transaction",
                                                swjdp->ack);
                                return ERROR_JTAG_DEVICE_ERROR;
                        }

                        adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat);
                        if ((retval = jtag_execute_queue()) != ERROR_OK)
                                return retval;
                        swjdp->ack = swjdp->ack & 0x7;
                }
        }

        /* REVISIT also STICKYCMP, for pushed comparisons (nyet used) */

        /* Check for STICKYERR and STICKYORUN */
        if (ctrlstat & (SSTICKYORUN | SSTICKYERR))
        {
                LOG_DEBUG("jtag-dp: CTRL/STAT error, 0x%" PRIx32, ctrlstat);
                /* Check power to debug regions */
                if ((ctrlstat & 0xf0000000) != 0xf0000000)
                         ahbap_debugport_init(swjdp);
                else
                {
                        uint32_t mem_ap_csw, mem_ap_tar;

                        /* Maybe print information about last intended
                         * MEM-AP access; but not if autoincrementing.
                         * *Real* CSW and TAR values are always shown.
                         */
                        if (swjdp->ap_tar_value != (uint32_t) -1)
                                LOG_DEBUG("MEM-AP Cached values: "
                                        "ap_bank 0x%" PRIx32
                                        ", ap_csw 0x%" PRIx32
                                        ", ap_tar 0x%" PRIx32,
                                        swjdp->ap_bank_value,
                                        swjdp->ap_csw_value,
                                        swjdp->ap_tar_value);

                        if (ctrlstat & SSTICKYORUN)
                                LOG_ERROR("JTAG-DP OVERRUN - check clock, "
                                        "memaccess, or reduce jtag speed");

                        if (ctrlstat & SSTICKYERR)
                                LOG_ERROR("JTAG-DP STICKY ERROR");

                        /* Clear Sticky Error Bits */
                        adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                                        DP_CTRL_STAT, DPAP_WRITE,
                                        swjdp->dp_ctrl_stat | SSTICKYORUN
                                                | SSTICKYERR, NULL);
                        adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                                        DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat);
                        if ((retval = jtag_execute_queue()) != ERROR_OK)
                                return retval;

                        LOG_DEBUG("jtag-dp: CTRL/STAT 0x%" PRIx32, ctrlstat);

                        dap_ap_read_reg_u32(swjdp, AP_REG_CSW, &mem_ap_csw);
                        dap_ap_read_reg_u32(swjdp, AP_REG_TAR, &mem_ap_tar);
                        if ((retval = jtag_execute_queue()) != ERROR_OK)
                                return retval;
                        LOG_ERROR("MEM_AP_CSW 0x%" PRIx32 ", MEM_AP_TAR 0x%"
                                        PRIx32, mem_ap_csw, mem_ap_tar);

                }
                if ((retval = jtag_execute_queue()) != ERROR_OK)
                        return retval;
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/***************************************************************************
 *                                                                         *
 * DP and MEM-AP  register access  through APACC and DPACC                 *
 *                                                                         *
***************************************************************************/

static int dap_dp_write_reg(struct swjdp_common *swjdp,
                uint32_t value, uint8_t reg_addr)
{
        return adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                        reg_addr, DPAP_WRITE, value, NULL);
}

static int dap_dp_read_reg(struct swjdp_common *swjdp,
                uint32_t *value, uint8_t reg_addr)
{
        return adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_DPACC,
                        reg_addr, DPAP_READ, 0, value);
}

/**
 * Select one of the APs connected to the specified DAP.  The
 * selection is implicitly used with future AP transactions.
 * This is a NOP if the specified AP is already selected.
 *
 * @param swjdp The DAP
 * @param apsel Number of the AP to (implicitly) use with further
 *      transactions.  This normally identifies a MEM-AP.
 */
void dap_ap_select(struct swjdp_common *swjdp,uint8_t apsel)
{
        uint32_t select = (apsel << 24) & 0xFF000000;

        if (select != swjdp->apsel)
        {
                swjdp->apsel = select;
                /* Switching AP invalidates cached values.
                 * Values MUST BE UPDATED BEFORE AP ACCESS.
                 */
                swjdp->ap_bank_value = -1;
                swjdp->ap_csw_value = -1;
                swjdp->ap_tar_value = -1;
        }
}

/** Select the AP register bank matching bits 7:4 of ap_reg. */
static int dap_ap_bankselect(struct swjdp_common *swjdp, uint32_t ap_reg)
{
        uint32_t select = (ap_reg & 0x000000F0);

        if (select != swjdp->ap_bank_value)
        {
                swjdp->ap_bank_value = select;
                select |= swjdp->apsel;
                return dap_dp_write_reg(swjdp, select, DP_SELECT);
        } else
                return ERROR_OK;
}

static int dap_ap_write_reg(struct swjdp_common *swjdp,
                uint32_t reg_addr, uint8_t *out_value_buf)
{
        int retval;

        retval = dap_ap_bankselect(swjdp, reg_addr);
        if (retval != ERROR_OK)
                return retval;

        return adi_jtag_ap_write_check(swjdp, reg_addr, out_value_buf);
}

/**
 * Asynchronous (queued) AP register write.
 *
 * @param swjdp The DAP whose currently selected AP will be written.
 * @param reg_addr Eight bit AP register address.
 * @param value Word to be written at reg_addr
 *
 * @return ERROR_OK if the transaction was properly queued, else a fault code.
 */
int dap_ap_write_reg_u32(struct swjdp_common *swjdp,
                uint32_t reg_addr, uint32_t value)
{
        uint8_t out_value_buf[4];

        buf_set_u32(out_value_buf, 0, 32, value);
        return dap_ap_write_reg(swjdp,
                        reg_addr, out_value_buf);
}

/**
 * Asynchronous (queued) AP register eread.
 *
 * @param swjdp The DAP whose currently selected AP will be read.
 * @param reg_addr Eight bit AP register address.
 * @param value Points to where the 32-bit (little-endian) word will be stored.
 *
 * @return ERROR_OK if the transaction was properly queued, else a fault code.
 */
int dap_ap_read_reg_u32(struct swjdp_common *swjdp,
                uint32_t reg_addr, uint32_t *value)
{
        int retval;

        retval = dap_ap_bankselect(swjdp, reg_addr);
        if (retval != ERROR_OK)
                return retval;

        return adi_jtag_scan_inout_check_u32(swjdp, JTAG_DP_APACC, reg_addr,
                        DPAP_READ, 0, value);
}

/**
 * Queue transactions setting up transfer parameters for the
 * currently selected MEM-AP.
 *
 * Subsequent transfers using registers like AP_REG_DRW or AP_REG_BD2
 * initiate data reads or writes using memory or peripheral addresses.
 * If the CSW is configured for it, the TAR may be automatically
 * incremented after each transfer.
 *
 * @todo Rename to reflect it being specifically a MEM-AP function.
 *
 * @param swjdp The DAP connected to the MEM-AP.
 * @param csw MEM-AP Control/Status Word (CSW) register to assign.  If this
 *      matches the cached value, the register is not changed.
 * @param tar MEM-AP Transfer Address Register (TAR) to assign.  If this
 *      matches the cached address, the register is not changed.
 *
 * @return ERROR_OK if the transaction was properly queued, else a fault code.
 */
int dap_setup_accessport(struct swjdp_common *swjdp, uint32_t csw, uint32_t tar)
{
        int retval;

        csw = csw | CSW_DBGSWENABLE | CSW_MASTER_DEBUG | CSW_HPROT;
        if (csw != swjdp->ap_csw_value)
        {
                /* LOG_DEBUG("DAP: Set CSW %x",csw); */
                retval = dap_ap_write_reg_u32(swjdp, AP_REG_CSW, csw);
                if (retval != ERROR_OK)
                        return retval;
                swjdp->ap_csw_value = csw;
        }
        if (tar != swjdp->ap_tar_value)
        {
                /* LOG_DEBUG("DAP: Set TAR %x",tar); */
                retval = dap_ap_write_reg_u32(swjdp, AP_REG_TAR, tar);
                if (retval != ERROR_OK)
                        return retval;
                swjdp->ap_tar_value = tar;
        }
        /* Disable TAR cache when autoincrementing */
        if (csw & CSW_ADDRINC_MASK)
                swjdp->ap_tar_value = -1;
        return ERROR_OK;
}

/**
 * Asynchronous (queued) read of a word from memory or a system register.
 *
 * @param swjdp The DAP connected to the MEM-AP performing the read.
 * @param address Address of the 32-bit word to read; it must be
 *      readable by the currently selected MEM-AP.
 * @param value points to where the word will be stored when the
 *      transaction queue is flushed (assuming no errors).
 *
 * @return ERROR_OK for success.  Otherwise a fault code.
 */
int mem_ap_read_u32(struct swjdp_common *swjdp, uint32_t address,
                uint32_t *value)
{
        int retval;

        /* Use banked addressing (REG_BDx) to avoid some link traffic
         * (updating TAR) when reading several consecutive addresses.
         */
        retval = dap_setup_accessport(swjdp, CSW_32BIT | CSW_ADDRINC_OFF,
                        address & 0xFFFFFFF0);
        if (retval != ERROR_OK)
                return retval;

        return dap_ap_read_reg_u32(swjdp, AP_REG_BD0 | (address & 0xC), value);
}

/**
 * Synchronous read of a word from memory or a system register.
 * As a side effect, this flushes any queued transactions.
 *
 * @param swjdp The DAP connected to the MEM-AP performing the read.
 * @param address Address of the 32-bit word to read; it must be
 *      readable by the currently selected MEM-AP.
 * @param value points to where the result will be stored.
 *
 * @return ERROR_OK for success; *value holds the result.
 * Otherwise a fault code.
 */
int mem_ap_read_atomic_u32(struct swjdp_common *swjdp, uint32_t address,
                uint32_t *value)
{
        int retval;

        retval = mem_ap_read_u32(swjdp, address, value);
        if (retval != ERROR_OK)
                return retval;

        return jtagdp_transaction_endcheck(swjdp);
}

/**
 * Asynchronous (queued) write of a word to memory or a system register.
 *
 * @param swjdp The DAP connected to the MEM-AP.
 * @param address Address to be written; it must be writable by
 *      the currently selected MEM-AP.
 * @param value Word that will be written to the address when transaction
 *      queue is flushed (assuming no errors).
 *
 * @return ERROR_OK for success.  Otherwise a fault code.
 */
int mem_ap_write_u32(struct swjdp_common *swjdp, uint32_t address,
                uint32_t value)
{
        int retval;

        /* Use banked addressing (REG_BDx) to avoid some link traffic
         * (updating TAR) when writing several consecutive addresses.
         */
        retval = dap_setup_accessport(swjdp, CSW_32BIT | CSW_ADDRINC_OFF,
                        address & 0xFFFFFFF0);
        if (retval != ERROR_OK)
                return retval;

        return dap_ap_write_reg_u32(swjdp, AP_REG_BD0 | (address & 0xC),
                        value);
}

/**
 * Synchronous write of a word to memory or a system register.
 * As a side effect, this flushes any queued transactions.
 *
 * @param swjdp The DAP connected to the MEM-AP.
 * @param address Address to be written; it must be writable by
 *      the currently selected MEM-AP.
 * @param value Word that will be written.
 *
 * @return ERROR_OK for success; the data was written.  Otherwise a fault code.
 */
int mem_ap_write_atomic_u32(struct swjdp_common *swjdp, uint32_t address,
                uint32_t value)
{
        int retval = mem_ap_write_u32(swjdp, address, value);

        if (retval != ERROR_OK)
                return retval;

        return jtagdp_transaction_endcheck(swjdp);
}

/*****************************************************************************
*                                                                            *
* mem_ap_write_buf(struct swjdp_common *swjdp, uint8_t *buffer, int count, uint32_t address) *
*                                                                            *
* Write a buffer in target order (little endian)                             *
*                                                                            *
*****************************************************************************/
int mem_ap_write_buf_u32(struct swjdp_common *swjdp, uint8_t *buffer, int count, uint32_t address)
{
        int wcount, blocksize, writecount, errorcount = 0, retval = ERROR_OK;
        uint32_t adr = address;
        uint8_t* pBuffer = buffer;

        count >>= 2;
        wcount = count;

        /* if we have an unaligned access - reorder data */
        if (adr & 0x3u)
        {
                for (writecount = 0; writecount < count; writecount++)
                {
                        int i;
                        uint32_t outvalue;
                        memcpy(&outvalue, pBuffer, sizeof(uint32_t));

                        for (i = 0; i < 4; i++)
                        {
                                *((uint8_t*)pBuffer + (adr & 0x3)) = outvalue;
                                outvalue >>= 8;
                                adr++;
                        }
                        pBuffer += sizeof(uint32_t);
                }
        }

        while (wcount > 0)
        {
                /* Adjust to write blocks within boundaries aligned to the TAR autoincremnent size*/
                blocksize = max_tar_block_size(swjdp->tar_autoincr_block, address);
                if (wcount < blocksize)
                        blocksize = wcount;

                /* handle unaligned data at 4k boundary */
                if (blocksize == 0)
                        blocksize = 1;

                dap_setup_accessport(swjdp, CSW_32BIT | CSW_ADDRINC_SINGLE, address);

                for (writecount = 0; writecount < blocksize; writecount++)
                {
                        dap_ap_write_reg(swjdp, AP_REG_DRW, buffer + 4 * writecount);
                }

                if (jtagdp_transaction_endcheck(swjdp) == ERROR_OK)
                {
                        wcount = wcount - blocksize;
                        address = address + 4 * blocksize;
                        buffer = buffer + 4 * blocksize;
                }
                else
                {
                        errorcount++;
                }

                if (errorcount > 1)
                {
                        LOG_WARNING("Block write error address 0x%" PRIx32 ", wcount 0x%x", address, wcount);
                        return ERROR_JTAG_DEVICE_ERROR;
                }
        }

        return retval;
}

static int mem_ap_write_buf_packed_u16(struct swjdp_common *swjdp,
                uint8_t *buffer, int count, uint32_t address)
{
        int retval = ERROR_OK;
        int wcount, blocksize, writecount, i;

        wcount = count >> 1;

        while (wcount > 0)
        {
                int nbytes;

                /* Adjust to write blocks within boundaries aligned to the TAR autoincremnent size*/
                blocksize = max_tar_block_size(swjdp->tar_autoincr_block, address);

                if (wcount < blocksize)
                        blocksize = wcount;

                /* handle unaligned data at 4k boundary */
                if (blocksize == 0)
                        blocksize = 1;

                dap_setup_accessport(swjdp, CSW_16BIT | CSW_ADDRINC_PACKED, address);
                writecount = blocksize;

                do
                {
                        nbytes = MIN((writecount << 1), 4);

                        if (nbytes < 4)
                        {
                                if (mem_ap_write_buf_u16(swjdp, buffer,
                                                nbytes, address) != ERROR_OK)
                                {
                                        LOG_WARNING("Block write error address "
                                                "0x%" PRIx32 ", count 0x%x",
                                                address, count);
                                        return ERROR_JTAG_DEVICE_ERROR;
                                }

                                address += nbytes >> 1;
                        }
                        else
                        {
                                uint32_t outvalue;
                                memcpy(&outvalue, buffer, sizeof(uint32_t));

                                for (i = 0; i < nbytes; i++)
                                {
                                        *((uint8_t*)buffer + (address & 0x3)) = outvalue;
                                        outvalue >>= 8;
                                        address++;
                                }

                                memcpy(&outvalue, buffer, sizeof(uint32_t));
                                dap_ap_write_reg_u32(swjdp, AP_REG_DRW, outvalue);
                                if (jtagdp_transaction_endcheck(swjdp) != ERROR_OK)
                                {
                                        LOG_WARNING("Block write error address "
                                                "0x%" PRIx32 ", count 0x%x",
                                                address, count);
                                        return ERROR_JTAG_DEVICE_ERROR;
                                }
                        }

                        buffer += nbytes >> 1;
                        writecount -= nbytes >> 1;

                } while (writecount);
                wcount -= blocksize;
        }

        return retval;
}

int mem_ap_write_buf_u16(struct swjdp_common *swjdp, uint8_t *buffer, int count, uint32_t address)
{
        int retval = ERROR_OK;

        if (count >= 4)
                return mem_ap_write_buf_packed_u16(swjdp, buffer, count, address);

        while (count > 0)
        {
                dap_setup_accessport(swjdp, CSW_16BIT | CSW_ADDRINC_SINGLE, address);
                uint16_t svalue;
                memcpy(&svalue, buffer, sizeof(uint16_t));
                uint32_t outvalue = (uint32_t)svalue << 8 * (address & 0x3);
                dap_ap_write_reg_u32(swjdp, AP_REG_DRW, outvalue);
                retval = jtagdp_transaction_endcheck(swjdp);
                count -= 2;
                address += 2;
                buffer += 2;
        }

        return retval;
}

static int mem_ap_write_buf_packed_u8(struct swjdp_common *swjdp,
                uint8_t *buffer, int count, uint32_t address)
{
        int retval = ERROR_OK;
        int wcount, blocksize, writecount, i;

        wcount = count;

        while (wcount > 0)
        {
                int nbytes;

                /* Adjust to write blocks within boundaries aligned to the TAR autoincremnent size*/
                blocksize = max_tar_block_size(swjdp->tar_autoincr_block, address);

                if (wcount < blocksize)
                        blocksize = wcount;

                dap_setup_accessport(swjdp, CSW_8BIT | CSW_ADDRINC_PACKED, address);
                writecount = blocksize;

                do
                {
                        nbytes = MIN(writecount, 4);

                        if (nbytes < 4)
                        {
                                if (mem_ap_write_buf_u8(swjdp, buffer, nbytes, address) != ERROR_OK)
                                {
                                        LOG_WARNING("Block write error address "
                                                "0x%" PRIx32 ", count 0x%x",
                                                address, count);
                                        return ERROR_JTAG_DEVICE_ERROR;
                                }

                                address += nbytes;
                        }
                        else
                        {
                                uint32_t outvalue;
                                memcpy(&outvalue, buffer, sizeof(uint32_t));

                                for (i = 0; i < nbytes; i++)
                                {
                                        *((uint8_t*)buffer + (address & 0x3)) = outvalue;
                                        outvalue >>= 8;
                                        address++;
                                }

                                memcpy(&outvalue, buffer, sizeof(uint32_t));
                                dap_ap_write_reg_u32(swjdp, AP_REG_DRW, outvalue);
                                if (jtagdp_transaction_endcheck(swjdp) != ERROR_OK)
                                {
                                        LOG_WARNING("Block write error address "
                                                "0x%" PRIx32 ", count 0x%x",
                                                address, count);
                                        return ERROR_JTAG_DEVICE_ERROR;
                                }
                        }

                        buffer += nbytes;
                        writecount -= nbytes;

                } while (writecount);
                wcount -= blocksize;
        }

        return retval;
}

int mem_ap_write_buf_u8(struct swjdp_common *swjdp, uint8_t *buffer, int count, uint32_t address)
{
        int retval = ERROR_OK;

        if (count >= 4)
                return mem_ap_write_buf_packed_u8(swjdp, buffer, count, address);

        while (count > 0)
        {
                dap_setup_accessport(swjdp, CSW_8BIT | CSW_ADDRINC_SINGLE, address);
                uint32_t outvalue = (uint32_t)*buffer << 8 * (address & 0x3);
                dap_ap_write_reg_u32(swjdp, AP_REG_DRW, outvalue);
                retval = jtagdp_transaction_endcheck(swjdp);
                count--;
                address++;
                buffer++;
        }

        return retval;
}

/**
 * Synchronously read a block of 32-bit words into a buffer
 * @param swjdp The DAP connected to the MEM-AP.
 * @param buffer where the words will be stored (in host byte order).
 * @param count How many words to read.
 * @param address Memory address from which to read words; all the
 *      words must be readable by the currently selected MEM-AP.
 */
int mem_ap_read_buf_u32(struct swjdp_common *swjdp, uint8_t *buffer,
                int count, uint32_t address)
{
        int wcount, blocksize, readcount, errorcount = 0, retval = ERROR_OK;
        uint32_t adr = address;
        uint8_t* pBuffer = buffer;

        count >>= 2;
        wcount = count;

        while (wcount > 0)
        {
                /* Adjust to read blocks within boundaries aligned to the
                 * TAR autoincrement size (at least 2^10).  Autoincrement
                 * mode avoids an extra per-word roundtrip to update TAR.
                 */
                blocksize = max_tar_block_size(swjdp->tar_autoincr_block,
                                address);
                if (wcount < blocksize)
                        blocksize = wcount;

                /* handle unaligned data at 4k boundary */
                if (blocksize == 0)
                        blocksize = 1;

                dap_setup_accessport(swjdp, CSW_32BIT | CSW_ADDRINC_SINGLE,
                                address);

                /* Scan out first read */
                adi_jtag_dp_scan(swjdp, JTAG_DP_APACC, AP_REG_DRW,
                                DPAP_READ, 0, NULL, NULL);
                for (readcount = 0; readcount < blocksize - 1; readcount++)
                {
                        /* Scan out next read; scan in posted value for the
                         * previous one.  Assumes read is acked "OK/FAULT",
                         * and CTRL_STAT says that meant "OK".
                         */
                        adi_jtag_dp_scan(swjdp, JTAG_DP_APACC, AP_REG_DRW,
                                        DPAP_READ, 0, buffer + 4 * readcount,
                                        &swjdp->ack);
                }

                /* Scan in last posted value; RDBUFF has no other effect,
                 * assuming ack is OK/FAULT and CTRL_STAT says "OK".
                 */
                adi_jtag_dp_scan(swjdp, JTAG_DP_DPACC, DP_RDBUFF,
                                DPAP_READ, 0, buffer + 4 * readcount,
                                &swjdp->ack);
                if (jtagdp_transaction_endcheck(swjdp) == ERROR_OK)
                {
                        wcount = wcount - blocksize;
                        address += 4 * blocksize;
                        buffer += 4 * blocksize;
                }
                else
                {
                        errorcount++;
                }

                if (errorcount > 1)
                {
                        LOG_WARNING("Block read error address 0x%" PRIx32
                                ", count 0x%x", address, count);
                        return ERROR_JTAG_DEVICE_ERROR;
                }
        }

        /* if we have an unaligned access - reorder data */
        if (adr & 0x3u)
        {
                for (readcount = 0; readcount < count; readcount++)
                {
                        int i;
                        uint32_t data;
                        memcpy(&data, pBuffer, sizeof(uint32_t));

                        for (i = 0; i < 4; i++)
                        {
                                *((uint8_t*)pBuffer) =
                                                (data >> 8 * (adr & 0x3));
                                pBuffer++;
                                adr++;
                        }
                }
        }

        return retval;
}

static int mem_ap_read_buf_packed_u16(struct swjdp_common *swjdp,
                uint8_t *buffer, int count, uint32_t address)
{
        uint32_t invalue;
        int retval = ERROR_OK;
        int wcount, blocksize, readcount, i;

        wcount = count >> 1;

        while (wcount > 0)
        {
                int nbytes;

                /* Adjust to read blocks within boundaries aligned to the TAR autoincremnent size*/
                blocksize = max_tar_block_size(swjdp->tar_autoincr_block, address);
                if (wcount < blocksize)
                        blocksize = wcount;

                dap_setup_accessport(swjdp, CSW_16BIT | CSW_ADDRINC_PACKED, address);

                /* handle unaligned data at 4k boundary */
                if (blocksize == 0)
                        blocksize = 1;
                readcount = blocksize;

                do
                {
                        dap_ap_read_reg_u32(swjdp, AP_REG_DRW, &invalue);
                        if (jtagdp_transaction_endcheck(swjdp) != ERROR_OK)
                        {
                                LOG_WARNING("Block read error address 0x%" PRIx32 ", count 0x%x", address, count);
                                return ERROR_JTAG_DEVICE_ERROR;
                        }

                        nbytes = MIN((readcount << 1), 4);

                        for (i = 0; i < nbytes; i++)
                        {
                                *((uint8_t*)buffer) = (invalue >> 8 * (address & 0x3));
                                buffer++;
                                address++;
                        }

                        readcount -= (nbytes >> 1);
                } while (readcount);
                wcount -= blocksize;
        }

        return retval;
}

/**
 * Synchronously read a block of 16-bit halfwords into a buffer
 * @param swjdp The DAP connected to the MEM-AP.
 * @param buffer where the halfwords will be stored (in host byte order).
 * @param count How many halfwords to read.
 * @param address Memory address from which to read words; all the
 *      words must be readable by the currently selected MEM-AP.
 */
int mem_ap_read_buf_u16(struct swjdp_common *swjdp, uint8_t *buffer,
                int count, uint32_t address)
{
        uint32_t invalue, i;
        int retval = ERROR_OK;

        if (count >= 4)
                return mem_ap_read_buf_packed_u16(swjdp, buffer, count, address);

        while (count > 0)
        {
                dap_setup_accessport(swjdp, CSW_16BIT | CSW_ADDRINC_SINGLE, address);
                dap_ap_read_reg_u32(swjdp, AP_REG_DRW, &invalue);
                retval = jtagdp_transaction_endcheck(swjdp);
                if (address & 0x1)
                {
                        for (i = 0; i < 2; i++)
                        {
                                *((uint8_t*)buffer) = (invalue >> 8 * (address & 0x3));
                                buffer++;
                                address++;
                        }
                }
                else
                {
                        uint16_t svalue = (invalue >> 8 * (address & 0x3));
                        memcpy(buffer, &svalue, sizeof(uint16_t));
                        address += 2;
                        buffer += 2;
                }
                count -= 2;
        }

        return retval;
}

/* FIX!!! is this a potential performance bottleneck w.r.t. requiring too many
 * roundtrips when jtag_execute_queue() has a large overhead(e.g. for USB)s?
 *
 * The solution is to arrange for a large out/in scan in this loop and
 * and convert data afterwards.
 */
static int mem_ap_read_buf_packed_u8(struct swjdp_common *swjdp,
                uint8_t *buffer, int count, uint32_t address)
{
        uint32_t invalue;
        int retval = ERROR_OK;
        int wcount, blocksize, readcount, i;

        wcount = count;

        while (wcount > 0)
        {
                int nbytes;

                /* Adjust to read blocks within boundaries aligned to the TAR autoincremnent size*/
                blocksize = max_tar_block_size(swjdp->tar_autoincr_block, address);

                if (wcount < blocksize)
                        blocksize = wcount;

                dap_setup_accessport(swjdp, CSW_8BIT | CSW_ADDRINC_PACKED, address);
                readcount = blocksize;

                do
                {
                        dap_ap_read_reg_u32(swjdp, AP_REG_DRW, &invalue);
                        if (jtagdp_transaction_endcheck(swjdp) != ERROR_OK)
                        {
                                LOG_WARNING("Block read error address 0x%" PRIx32 ", count 0x%x", address, count);
                                return ERROR_JTAG_DEVICE_ERROR;
                        }

                        nbytes = MIN(readcount, 4);

                        for (i = 0; i < nbytes; i++)
                        {
                                *((uint8_t*)buffer) = (invalue >> 8 * (address & 0x3));
                                buffer++;
                                address++;
                        }

                        readcount -= nbytes;
                } while (readcount);
                wcount -= blocksize;
        }

        return retval;
}

/**
 * Synchronously read a block of bytes into a buffer
 * @param swjdp The DAP connected to the MEM-AP.
 * @param buffer where the bytes will be stored.
 * @param count How many bytes to read.
 * @param address Memory address from which to read data; all the
 *      data must be readable by the currently selected MEM-AP.
 */
int mem_ap_read_buf_u8(struct swjdp_common *swjdp, uint8_t *buffer,
                int count, uint32_t address)
{
        uint32_t invalue;
        int retval = ERROR_OK;

        if (count >= 4)
                return mem_ap_read_buf_packed_u8(swjdp, buffer, count, address);

        while (count > 0)
        {
                dap_setup_accessport(swjdp, CSW_8BIT | CSW_ADDRINC_SINGLE, address);
                dap_ap_read_reg_u32(swjdp, AP_REG_DRW, &invalue);
                retval = jtagdp_transaction_endcheck(swjdp);
                *((uint8_t*)buffer) = (invalue >> 8 * (address & 0x3));
                count--;
                address++;
                buffer++;
        }

        return retval;
}

/**
 * Initialize a DAP.  This sets up the power domains, prepares the DP
 * for further use, and arranges to use AP #0 for all AP operations
 * until dap_ap-select() changes that policy.
 *
 * @param swjdp The DAP being initialized.
 *
 * @todo Rename this.  We also need an initialization scheme which account
 * for SWD transports not just JTAG; that will need to address differences
 * in layering.  (JTAG is useful without any debug target; but not SWD.)
 * And this may not even use an AHB-AP ... e.g. DAP-Lite uses an APB-AP.
 */
int ahbap_debugport_init(struct swjdp_common *swjdp)
{
        uint32_t idreg, romaddr, dummy;
        uint32_t ctrlstat;
        int cnt = 0;
        int retval;

        LOG_DEBUG(" ");

        /* Default MEM-AP setup.
         *
         * REVISIT AP #0 may be an inappropriate default for this.
         * Should we probe, or take a hint from the caller?
         * Presumably we can ignore the possibility of multiple APs.
         */
        swjdp->apsel = !0;
        dap_ap_select(swjdp, 0);

        /* DP initialization */
        dap_dp_read_reg(swjdp, &dummy, DP_CTRL_STAT);
        dap_dp_write_reg(swjdp, SSTICKYERR, DP_CTRL_STAT);
        dap_dp_read_reg(swjdp, &dummy, DP_CTRL_STAT);

        swjdp->dp_ctrl_stat = CDBGPWRUPREQ | CSYSPWRUPREQ;

        dap_dp_write_reg(swjdp, swjdp->dp_ctrl_stat, DP_CTRL_STAT);
        dap_dp_read_reg(swjdp, &ctrlstat, DP_CTRL_STAT);
        if ((retval = jtag_execute_queue()) != ERROR_OK)
                return retval;

        /* Check that we have debug power domains activated */
        while (!(ctrlstat & CDBGPWRUPACK) && (cnt++ < 10))
        {
                LOG_DEBUG("DAP: wait CDBGPWRUPACK");
                dap_dp_read_reg(swjdp, &ctrlstat, DP_CTRL_STAT);
                if ((retval = jtag_execute_queue()) != ERROR_OK)
                        return retval;
                alive_sleep(10);
        }

        while (!(ctrlstat & CSYSPWRUPACK) && (cnt++ < 10))
        {
                LOG_DEBUG("DAP: wait CSYSPWRUPACK");
                dap_dp_read_reg(swjdp, &ctrlstat, DP_CTRL_STAT);
                if ((retval = jtag_execute_queue()) != ERROR_OK)
                        return retval;
                alive_sleep(10);
        }

        dap_dp_read_reg(swjdp, &dummy, DP_CTRL_STAT);
        /* With debug power on we can activate OVERRUN checking */
        swjdp->dp_ctrl_stat = CDBGPWRUPREQ | CSYSPWRUPREQ | CORUNDETECT;
        dap_dp_write_reg(swjdp, swjdp->dp_ctrl_stat, DP_CTRL_STAT);
        dap_dp_read_reg(swjdp, &dummy, DP_CTRL_STAT);

        /*
         * REVISIT this isn't actually *initializing* anything in an AP,
         * and doesn't care if it's a MEM-AP at all (much less AHB-AP).
         * Should it?  If the ROM address is valid, is this the right
         * place to scan the table and do any topology detection?
         */
        dap_ap_read_reg_u32(swjdp, AP_REG_IDR, &idreg);
        dap_ap_read_reg_u32(swjdp, AP_REG_BASE, &romaddr);

        LOG_DEBUG("MEM-AP #%d ID Register 0x%" PRIx32
                ", Debug ROM Address 0x%" PRIx32,
                swjdp->apsel, idreg, romaddr);

        return ERROR_OK;
}

/* CID interpretation -- see ARM IHI 0029B section 3
 * and ARM IHI 0031A table 13-3.
 */
static const char *class_description[16] ={
        "Reserved", "ROM table", "Reserved", "Reserved",
        "Reserved", "Reserved", "Reserved", "Reserved",
        "Reserved", "CoreSight component", "Reserved", "Peripheral Test Block",
        "Reserved", "OptimoDE DESS",
                "Generic IP component", "PrimeCell or System component"
};

static bool
is_dap_cid_ok(uint32_t cid3, uint32_t cid2, uint32_t cid1, uint32_t cid0)
{
        return cid3 == 0xb1 && cid2 == 0x05
                        && ((cid1 & 0x0f) == 0) && cid0 == 0x0d;
}

int dap_info_command(struct command_context *cmd_ctx,
                struct swjdp_common *swjdp, int apsel)
{

        uint32_t dbgbase, apid;
        int romtable_present = 0;
        uint8_t mem_ap;
        uint32_t apselold;

        /* AP address is in bits 31:24 of DP_SELECT */
        if (apsel >= 256)
                return ERROR_INVALID_ARGUMENTS;

        apselold = swjdp->apsel;
        dap_ap_select(swjdp, apsel);
        dap_ap_read_reg_u32(swjdp, AP_REG_BASE, &dbgbase);
        dap_ap_read_reg_u32(swjdp, AP_REG_IDR, &apid);
        jtagdp_transaction_endcheck(swjdp);
        /* Now we read ROM table ID registers, ref. ARM IHI 0029B sec  */
        mem_ap = ((apid&0x10000) && ((apid&0x0F) != 0));
        command_print(cmd_ctx, "AP ID register 0x%8.8" PRIx32, apid);
        if (apid)
        {
                switch (apid&0x0F)
                {
                        case 0:
                                command_print(cmd_ctx, "\tType is JTAG-AP");
                                break;
                        case 1:
                                command_print(cmd_ctx, "\tType is MEM-AP AHB");
                                break;
                        case 2:
                                command_print(cmd_ctx, "\tType is MEM-AP APB");
                                break;
                        default:
                                command_print(cmd_ctx, "\tUnknown AP type");
                                break;
                }

                /* NOTE: a MEM-AP may have a single CoreSight component that's
                 * not a ROM table ... or have no such components at all.
                 */
                if (mem_ap)
                        command_print(cmd_ctx, "AP BASE 0x%8.8" PRIx32,
                                        dbgbase);
        }
        else
        {
                command_print(cmd_ctx, "No AP found at this apsel 0x%x", apsel);
        }

        romtable_present = ((mem_ap) && (dbgbase != 0xFFFFFFFF));
        if (romtable_present)
        {
                uint32_t cid0,cid1,cid2,cid3,memtype,romentry;
                uint16_t entry_offset;

                /* bit 16 of apid indicates a memory access port */
                if (dbgbase & 0x02)
                        command_print(cmd_ctx, "\tValid ROM table present");
                else
                        command_print(cmd_ctx, "\tROM table in legacy format");

                /* Now we read ROM table ID registers, ref. ARM IHI 0029B sec  */
                mem_ap_read_u32(swjdp, (dbgbase&0xFFFFF000) | 0xFF0, &cid0);
                mem_ap_read_u32(swjdp, (dbgbase&0xFFFFF000) | 0xFF4, &cid1);
                mem_ap_read_u32(swjdp, (dbgbase&0xFFFFF000) | 0xFF8, &cid2);
                mem_ap_read_u32(swjdp, (dbgbase&0xFFFFF000) | 0xFFC, &cid3);
                mem_ap_read_u32(swjdp, (dbgbase&0xFFFFF000) | 0xFCC, &memtype);
                jtagdp_transaction_endcheck(swjdp);
                if (!is_dap_cid_ok(cid3, cid2, cid1, cid0))
                        command_print(cmd_ctx, "\tCID3 0x%2.2" PRIx32
                                        ", CID2 0x%2.2" PRIx32
                                        ", CID1 0x%2.2" PRIx32
                                        ", CID0 0x%2.2" PRIx32,
                                        cid3, cid2, cid1, cid0);
                if (memtype & 0x01)
                        command_print(cmd_ctx, "\tMEMTYPE system memory present on bus");
                else
                        command_print(cmd_ctx, "\tMEMTYPE System memory not present. "
                                        "Dedicated debug bus.");

                /* Now we read ROM table entries from dbgbase&0xFFFFF000) | 0x000 until we get 0x00000000 */
                entry_offset = 0;
                do
                {
                        mem_ap_read_atomic_u32(swjdp, (dbgbase&0xFFFFF000) | entry_offset, &romentry);
                        command_print(cmd_ctx, "\tROMTABLE[0x%x] = 0x%" PRIx32 "",entry_offset,romentry);
                        if (romentry&0x01)
                        {
                                uint32_t c_cid0, c_cid1, c_cid2, c_cid3;
                                uint32_t c_pid0, c_pid1, c_pid2, c_pid3, c_pid4;
                                uint32_t component_start, component_base;
                                unsigned part_num;
                                char *type, *full;

                                component_base = (uint32_t)((dbgbase & 0xFFFFF000)
                                                + (int)(romentry & 0xFFFFF000));
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFE0, &c_pid0);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFE4, &c_pid1);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFE8, &c_pid2);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFEC, &c_pid3);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFD0, &c_pid4);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFF0, &c_cid0);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFF4, &c_cid1);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFF8, &c_cid2);
                                mem_ap_read_atomic_u32(swjdp,
                                                (component_base & 0xFFFFF000) | 0xFFC, &c_cid3);
                                component_start = component_base - 0x1000*(c_pid4 >> 4);

                                command_print(cmd_ctx, "\t\tComponent base address 0x%" PRIx32
                                                ", start address 0x%" PRIx32,
                                                component_base, component_start);
                                command_print(cmd_ctx, "\t\tComponent class is 0x%x, %s",
                                                (int) (c_cid1 >> 4) & 0xf,
                                                /* See ARM IHI 0029B Table 3-3 */
                                                class_description[(c_cid1 >> 4) & 0xf]);

                                /* CoreSight component? */
                                if (((c_cid1 >> 4) & 0x0f) == 9) {
                                        uint32_t devtype;
                                        unsigned minor;
                                        char *major = "Reserved", *subtype = "Reserved";

                                        mem_ap_read_atomic_u32(swjdp,
                                                        (component_base & 0xfffff000) | 0xfcc,
                                                        &devtype);
                                        minor = (devtype >> 4) & 0x0f;
                                        switch (devtype & 0x0f) {
                                        case 0:
                                                major = "Miscellaneous";
                                                switch (minor) {
                                                case 0:
                                                        subtype = "other";
                                                        break;
                                                case 4:
                                                        subtype = "Validation component";
                                                        break;
                                                }
                                                break;
                                        case 1:
                                                major = "Trace Sink";
                                                switch (minor) {
                                                case 0:
                                                        subtype = "other";
                                                        break;
                                                case 1:
                                                        subtype = "Port";
                                                        break;
                                                case 2:
                                                        subtype = "Buffer";
                                                        break;
                                                }
                                                break;
                                        case 2:
                                                major = "Trace Link";
                                                switch (minor) {
                                                case 0:
                                                        subtype = "other";
                                                        break;
                                                case 1:
                                                        subtype = "Funnel, router";
                                                        break;
                                                case 2:
                                                        subtype = "Filter";
                                                        break;
                                                case 3:
                                                        subtype = "FIFO, buffer";
                                                        break;
                                                }
                                                break;
                                        case 3:
                                                major = "Trace Source";
                                                switch (minor) {
                                                case 0:
                                                        subtype = "other";
                                                        break;
                                                case 1:
                                                        subtype = "Processor";
                                                        break;
                                                case 2:
                                                        subtype = "DSP";
                                                        break;
                                                case 3:
                                                        subtype = "Engine/Coprocessor";
                                                        break;
                                                case 4:
                                                        subtype = "Bus";
                                                        break;
                                                }
                                                break;
                                        case 4:
                                                major = "Debug Control";
                                                switch (minor) {
                                                case 0:
                                                        subtype = "other";
                                                        break;
                                                case 1:
                                                        subtype = "Trigger Matrix";
                                                        break;
                                                case 2:
                                                        subtype = "Debug Auth";
                                                        break;
                                                }
                                                break;
                                        case 5:
                                                major = "Debug Logic";
                                                switch (minor) {
                                                case 0:
                                                        subtype = "other";
                                                        break;
                                                case 1:
                                                        subtype = "Processor";
                                                        break;
                                                case 2:
                                                        subtype = "DSP";
                                                        break;
                                                case 3:
                                                        subtype = "Engine/Coprocessor";
                                                        break;
                                                }
                                                break;
                                        }
                                        command_print(cmd_ctx, "\t\tType is 0x%2.2x, %s, %s",
                                                        (unsigned) (devtype & 0xff),
                                                        major, subtype);
                                        /* REVISIT also show 0xfc8 DevId */
                                }

                                if (!is_dap_cid_ok(cid3, cid2, cid1, cid0))
                                        command_print(cmd_ctx, "\t\tCID3 0x%2.2" PRIx32
                                                        ", CID2 0x%2.2" PRIx32
                                                        ", CID1 0x%2.2" PRIx32
                                                        ", CID0 0x%2.2" PRIx32,
                                                        c_cid3, c_cid2, c_cid1, c_cid0);
                                command_print(cmd_ctx, "\t\tPeripheral ID[4..0] = hex "
                                                "%2.2x %2.2x %2.2x %2.2x %2.2x",
                                                (int) c_pid4,
                                                (int) c_pid3, (int) c_pid2,
                                                (int) c_pid1, (int) c_pid0);

                                /* Part number interpretations are from Cortex
                                 * core specs, the CoreSight components TRM
                                 * (ARM DDI 0314H), and ETM specs; also from
                                 * chip observation (e.g. TI SDTI).
                                 */
                                part_num = c_pid0 & 0xff;
                                part_num |= (c_pid1 & 0x0f) << 8;
                                switch (part_num) {
                                case 0x000:
                                        type = "Cortex-M3 NVIC";
                                        full = "(Interrupt Controller)";
                                        break;
                                case 0x001:
                                        type = "Cortex-M3 ITM";
                                        full = "(Instrumentation Trace Module)";
                                        break;
                                case 0x002:
                                        type = "Cortex-M3 DWT";
                                        full = "(Data Watchpoint and Trace)";
                                        break;
                                case 0x003:
                                        type = "Cortex-M3 FBP";
                                        full = "(Flash Patch and Breakpoint)";
                                        break;
                                case 0x00d:
                                        type = "CoreSight ETM11";
                                        full = "(Embedded Trace)";
                                        break;
                                // case 0x113: what?
                                case 0x120:             /* from OMAP3 memmap */
                                        type = "TI SDTI";
                                        full = "(System Debug Trace Interface)";
                                        break;
                                case 0x343:             /* from OMAP3 memmap */
                                        type = "TI DAPCTL";
                                        full = "";
                                        break;
                                case 0x906:
                                        type = "Coresight CTI";
                                        full = "(Cross Trigger)";
                                        break;
                                case 0x907:
                                        type = "Coresight ETB";
                                        full = "(Trace Buffer)";
                                        break;
                                case 0x908:
                                        type = "Coresight CSTF";
                                        full = "(Trace Funnel)";
                                        break;
                                case 0x910:
                                        type = "CoreSight ETM9";
                                        full = "(Embedded Trace)";
                                        break;
                                case 0x912:
                                        type = "Coresight TPIU";
                                        full = "(Trace Port Interface Unit)";
                                        break;
                                case 0x921:
                                        type = "Cortex-A8 ETM";
                                        full = "(Embedded Trace)";
                                        break;
                                case 0x922:
                                        type = "Cortex-A8 CTI";
                                        full = "(Cross Trigger)";
                                        break;
                                case 0x923:
                                        type = "Cortex-M3 TPIU";
                                        full = "(Trace Port Interface Unit)";
                                        break;
                                case 0x924:
                                        type = "Cortex-M3 ETM";
                                        full = "(Embedded Trace)";
                                        break;
                                case 0xc08:
                                        type = "Cortex-A8 Debug";
                                        full = "(Debug Unit)";
                                        break;
                                default:
                                        type = "-*- unrecognized -*-";
                                        full = "";
                                        break;
                                }
                                command_print(cmd_ctx, "\t\tPart is %s %s",
                                                type, full);
                        }
                        else
                        {
                                if (romentry)
                                        command_print(cmd_ctx, "\t\tComponent not present");
                                else
                                        command_print(cmd_ctx, "\t\tEnd of ROM table");
                        }
                        entry_offset += 4;
                } while (romentry > 0);
        }
        else
        {
                command_print(cmd_ctx, "\tNo ROM table present");
        }
        dap_ap_select(swjdp, apselold);

        return ERROR_OK;
}

DAP_COMMAND_HANDLER(dap_baseaddr_command)
{
        uint32_t apsel, apselsave, baseaddr;
        int retval;

        apselsave = swjdp->apsel;
        switch (CMD_ARGC) {
        case 0:
                apsel = swjdp->apsel;
                break;
        case 1:
                COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], apsel);
                /* AP address is in bits 31:24 of DP_SELECT */
                if (apsel >= 256)
                        return ERROR_INVALID_ARGUMENTS;
                break;
        default:
                return ERROR_COMMAND_SYNTAX_ERROR;
        }

        if (apselsave != apsel)
                dap_ap_select(swjdp, apsel);

        /* NOTE:  assumes we're talking to a MEM-AP, which
         * has a base address.  There are other kinds of AP,
         * though they're not common for now.  This should
         * use the ID register to verify it's a MEM-AP.
         */
        dap_ap_read_reg_u32(swjdp, AP_REG_BASE, &baseaddr);
        retval = jtagdp_transaction_endcheck(swjdp);
        command_print(CMD_CTX, "0x%8.8" PRIx32, baseaddr);

        if (apselsave != apsel)
                dap_ap_select(swjdp, apselsave);

        return retval;
}

DAP_COMMAND_HANDLER(dap_memaccess_command)
{
        uint32_t memaccess_tck;

        switch (CMD_ARGC) {
        case 0:
                memaccess_tck = swjdp->memaccess_tck;
                break;
        case 1:
                COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], memaccess_tck);
                break;
        default:
                return ERROR_COMMAND_SYNTAX_ERROR;
        }
        swjdp->memaccess_tck = memaccess_tck;

        command_print(CMD_CTX, "memory bus access delay set to %" PRIi32 " tck",
                        swjdp->memaccess_tck);

        return ERROR_OK;
}

DAP_COMMAND_HANDLER(dap_apsel_command)
{
        uint32_t apsel, apid;
        int retval;

        switch (CMD_ARGC) {
        case 0:
                apsel = 0;
                break;
        case 1:
                COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], apsel);
                /* AP address is in bits 31:24 of DP_SELECT */
                if (apsel >= 256)
                        return ERROR_INVALID_ARGUMENTS;
                break;
        default:
                return ERROR_COMMAND_SYNTAX_ERROR;
        }

        dap_ap_select(swjdp, apsel);
        dap_ap_read_reg_u32(swjdp, AP_REG_IDR, &apid);
        retval = jtagdp_transaction_endcheck(swjdp);
        command_print(CMD_CTX, "ap %" PRIi32 " selected, identification register 0x%8.8" PRIx32,
                        apsel, apid);

        return retval;
}

DAP_COMMAND_HANDLER(dap_apid_command)
{
        uint32_t apsel, apselsave, apid;
        int retval;

        apselsave = swjdp->apsel;
        switch (CMD_ARGC) {
        case 0:
                apsel = swjdp->apsel;
                break;
        case 1:
                COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], apsel);
                /* AP address is in bits 31:24 of DP_SELECT */
                if (apsel >= 256)
                        return ERROR_INVALID_ARGUMENTS;
                break;
        default:
                return ERROR_COMMAND_SYNTAX_ERROR;
        }

        if (apselsave != apsel)
                dap_ap_select(swjdp, apsel);

        dap_ap_read_reg_u32(swjdp, AP_REG_IDR, &apid);
        retval = jtagdp_transaction_endcheck(swjdp);
        command_print(CMD_CTX, "0x%8.8" PRIx32, apid);
        if (apselsave != apsel)
                dap_ap_select(swjdp, apselsave);

        return retval;
}

/*
 * This represents the bits which must be sent out on TMS/SWDIO to
 * switch a DAP implemented using an SWJ-DP module into SWD mode.
 * These bits are stored (and transmitted) LSB-first.
 *
 * See the DAP-Lite specification, section 2.2.5 for information
 * about making the debug link select SWD or JTAG.  (Similar info
 * is in a few other ARM documents.)
 */
static const uint8_t jtag2swd_bitseq[] = {
        /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
         * putting both JTAG and SWD logic into reset state.
         */
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        /* Switching sequence enables SWD and disables JTAG
         * NOTE: bits in the DP's IDCODE may expose the need for
         * an old/deprecated sequence (0xb6 0xed).
         */
        0x9e, 0xe7,
        /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
         * putting both JTAG and SWD logic into reset state.
         */
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};

/**
 * Put the debug link into SWD mode, if the target supports it.
 * The link's initial mode may be either JTAG (for example,
 * with SWJ-DP after reset) or SWD.
 *
 * @param target Enters SWD mode (if possible).
 *
 * Note that targets using the JTAG-DP do not support SWD, and that
 * some targets which could otherwise support it may have have been
 * configured to disable SWD signaling
 *
 * @return ERROR_OK or else a fault code.
 */
int dap_to_swd(struct target *target)
{
        int retval;

        LOG_DEBUG("Enter SWD mode");

        /* REVISIT it's nasty to need to make calls to a "jtag"
         * subsystem if the link isn't in JTAG mode...
         */

        retval =  jtag_add_tms_seq(8 * sizeof(jtag2swd_bitseq),
                        jtag2swd_bitseq, TAP_INVALID);
        if (retval == ERROR_OK)
                retval = jtag_execute_queue();

        /* REVISIT set up the DAP's ops vector for SWD mode. */

        return retval;
}

/**
 * This represents the bits which must be sent out on TMS/SWDIO to
 * switch a DAP implemented using an SWJ-DP module into JTAG mode.
 * These bits are stored (and transmitted) LSB-first.
 *
 * These bits are stored (and transmitted) LSB-first.
 */
static const uint8_t swd2jtag_bitseq[] = {
        /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
         * putting both JTAG and SWD logic into reset state.
         */
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        /* Switching equence disables SWD and enables JTAG
         * NOTE: bits in the DP's IDCODE can expose the need for
         * the old/deprecated sequence (0xae 0xde).
         */
        0x3c, 0xe7,
        /* At least 50 TCK/SWCLK cycles with TMS/SWDIO high,
         * putting both JTAG and SWD logic into reset state.
         * NOTE:  some docs say "at least 5".
         */
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};

/** Put the debug link into JTAG mode, if the target supports it.
 * The link's initial mode may be either SWD or JTAG.
 *
 * @param target Enters JTAG mode (if possible).
 *
 * Note that targets implemented with SW-DP do not support JTAG, and
 * that some targets which could otherwise support it may have been
 * configured to disable JTAG signaling
 *
 * @return ERROR_OK or else a fault code.
 */
int dap_to_jtag(struct target *target)
{
        int retval;

        LOG_DEBUG("Enter JTAG mode");

        /* REVISIT it's nasty to need to make calls to a "jtag"
         * subsystem if the link isn't in JTAG mode...
         */

        retval = jtag_add_tms_seq(8 * sizeof(swd2jtag_bitseq),
                        swd2jtag_bitseq, TAP_RESET);
        if (retval == ERROR_OK)
                retval = jtag_execute_queue();

        /* REVISIT set up the DAP's ops vector for JTAG mode. */

        return retval;
}