arm7tdmi.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   Copyright (C) 2007,2008 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include "arm7tdmi.h"
#include "target_type.h"
#include "register.h"
#include "arm_opcodes.h"
#include "arm_semihosting.h"
 
/*
 * For information about ARM7TDMI, see ARM DDI 0210C (r4p1)
 * or ARM DDI 0029G (r3).  "Debug In Depth", Appendix B,
 * covers JTAG support.
 */
 
#if 0
#define _DEBUG_INSTRUCTION_EXECUTION_
#endif
 
static int arm7tdmi_examine_debug_reason(struct target *target)
{
    int retval = ERROR_OK;
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
 
    /* only check the debug reason if we don't know it already */
    if ((target->debug_reason != DBG_REASON_DBGRQ)
            && (target->debug_reason != DBG_REASON_SINGLESTEP)) {
        struct scan_field fields[2];
        uint8_t databus[4];
        uint8_t breakpoint;
 
        fields[0].num_bits = 1;
        fields[0].out_value = NULL;
        fields[0].in_value = &breakpoint;
 
        fields[1].num_bits = 32;
        fields[1].out_value = NULL;
        fields[1].in_value = databus;
 
        retval = arm_jtag_scann(&arm7_9->jtag_info, 0x1, TAP_DRPAUSE);
        if (retval != ERROR_OK)
            return retval;
        retval = arm_jtag_set_instr(arm7_9->jtag_info.tap, arm7_9->jtag_info.intest_instr, NULL, TAP_DRPAUSE);
        if (retval != ERROR_OK)
            return retval;
 
        jtag_add_dr_scan(arm7_9->jtag_info.tap, 2, fields, TAP_DRPAUSE);
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
            return retval;
 
        fields[0].in_value = NULL;
        fields[0].out_value = &breakpoint;
        fields[1].in_value = NULL;
        fields[1].out_value = databus;
 
        jtag_add_dr_scan(arm7_9->jtag_info.tap, 2, fields, TAP_DRPAUSE);
 
        if (breakpoint & 1)
            target->debug_reason = DBG_REASON_WATCHPOINT;
        else
            target->debug_reason = DBG_REASON_BREAKPOINT;
    }
 
    return ERROR_OK;
}
 
static const int arm7tdmi_num_bits[] = {1, 32};
 
static inline int arm7tdmi_clock_out_inner(struct arm_jtag *jtag_info, uint32_t out, int breakpoint)
{
    uint8_t bp = breakpoint ? 1 : 0;
    uint8_t out_value[4];
    buf_set_u32(out_value, 0, 32, flip_u32(out, 32));
 
    struct scan_field fields[2] = {
            { .num_bits = arm7tdmi_num_bits[0], .out_value = &bp },
            { .num_bits = arm7tdmi_num_bits[1], .out_value = out_value },
    };
 
    jtag_add_dr_scan(jtag_info->tap,
            2,
            fields,
            TAP_DRPAUSE);
 
    jtag_add_runtest(0, TAP_DRPAUSE);
 
    return ERROR_OK;
}
 
/* put an instruction in the ARM7TDMI pipeline or write the data bus,
 * and optionally read data
 */
static inline int arm7tdmi_clock_out(struct arm_jtag *jtag_info,
        uint32_t out, int breakpoint)
{
    int retval;
    retval = arm_jtag_scann(jtag_info, 0x1, TAP_DRPAUSE);
    if (retval != ERROR_OK)
        return retval;
    retval = arm_jtag_set_instr(jtag_info->tap, jtag_info->intest_instr, NULL, TAP_DRPAUSE);
    if (retval != ERROR_OK)
        return retval;
 
    return arm7tdmi_clock_out_inner(jtag_info, out, breakpoint);
}
 
/* clock the target, reading the databus */
static int arm7tdmi_clock_data_in(struct arm_jtag *jtag_info, uint32_t *in)
{
    int retval = ERROR_OK;
    struct scan_field fields[2];
 
    retval = arm_jtag_scann(jtag_info, 0x1, TAP_DRPAUSE);
    if (retval != ERROR_OK)
        return retval;
    retval = arm_jtag_set_instr(jtag_info->tap, jtag_info->intest_instr, NULL, TAP_DRPAUSE);
    if (retval != ERROR_OK)
        return retval;
 
    fields[0].num_bits = 1;
    fields[0].out_value = NULL;
    fields[0].in_value = NULL;
 
    fields[1].num_bits = 32;
    fields[1].out_value = NULL;
    fields[1].in_value = (uint8_t *)in;
 
    jtag_add_dr_scan(jtag_info->tap, 2, fields, TAP_DRPAUSE);
 
    jtag_add_callback(arm7flip32, (jtag_callback_data_t)in);
 
    jtag_add_runtest(0, TAP_DRPAUSE);
 
#ifdef _DEBUG_INSTRUCTION_EXECUTION_
    retval = jtag_execute_queue();
    if (retval != ERROR_OK)
        return retval;
 
    if (in)
        LOG_DEBUG("in: 0x%8.8x", *in);
    else
        LOG_ERROR("BUG: called with in == NULL");
#endif
 
    return ERROR_OK;
}
 
/* clock the target, and read the databus
 * the *in pointer points to a buffer where elements of 'size' bytes
 * are stored in big (be == 1) or little (be == 0) endianness
 */
static int arm7tdmi_clock_data_in_endianness(struct arm_jtag *jtag_info,
        void *in, int size, int be)
{
    int retval = ERROR_OK;
    struct scan_field fields[3];
 
    retval = arm_jtag_scann(jtag_info, 0x1, TAP_DRPAUSE);
    if (retval != ERROR_OK)
        return retval;
    retval = arm_jtag_set_instr(jtag_info->tap, jtag_info->intest_instr, NULL, TAP_DRPAUSE);
    if (retval != ERROR_OK)
        return retval;
 
    fields[0].num_bits = 1;
    fields[0].out_value = NULL;
    fields[0].in_value = NULL;
 
    if (size == 4) {
        fields[1].num_bits = 32;
        fields[1].out_value = NULL;
        fields[1].in_value = in;
    } else {
        /* Discard irrelevant bits of the scan, making sure we don't write more
         * than size bytes to in */
        fields[1].num_bits = 32 - size * 8;
        fields[1].out_value = NULL;
        fields[1].in_value = NULL;
 
        fields[2].num_bits = size * 8;
        fields[2].out_value = NULL;
        fields[2].in_value = in;
    }
 
    jtag_add_dr_scan(jtag_info->tap, size == 4 ? 2 : 3, fields, TAP_DRPAUSE);
 
    jtag_add_callback4(arm7_9_endianness_callback,
        (jtag_callback_data_t)in,
        (jtag_callback_data_t)size,
        (jtag_callback_data_t)be,
        (jtag_callback_data_t)1);
 
    jtag_add_runtest(0, TAP_DRPAUSE);
 
#ifdef _DEBUG_INSTRUCTION_EXECUTION_
{
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
            return retval;
 
        if (in)
            LOG_DEBUG("in: 0x%8.8x", *(uint32_t *)in);
        else
            LOG_ERROR("BUG: called with in == NULL");
}
#endif
 
    return ERROR_OK;
}
 
static void arm7tdmi_change_to_arm(struct target *target,
        uint32_t *r0, uint32_t *pc)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* save r0 before using it and put system in ARM state
     * to allow common handling of ARM and THUMB debugging */
 
    /* fetch STR r0, [r0] */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_STR(0, 0), 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    /* nothing fetched, STR r0, [r0] in Execute (2) */
    arm7tdmi_clock_data_in(jtag_info, r0);
 
    /* MOV r0, r15 fetched, STR in Decode */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_MOV(0, 15), 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_STR(0, 0), 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    /* nothing fetched, STR r0, [r0] in Execute (2) */
    arm7tdmi_clock_data_in(jtag_info, pc);
 
    /* use pc-relative LDR to clear r0[1:0] (for switch to ARM mode) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_LDR_PCREL(0), 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    /* nothing fetched, data for LDR r0, [PC, #0] */
    arm7tdmi_clock_out(jtag_info, 0x0, 0);
    /* nothing fetched, data from previous cycle is written to register */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
 
    /* fetch BX */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_BX(0), 0);
    /* NOP fetched, BX in Decode, MOV in Execute */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    /* NOP fetched, BX in Execute (1) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
 
    jtag_execute_queue();
 
    /* fix program counter:
     * MOV r0, r15 was the 4th instruction (+6)
     * reading PC in Thumb state gives address of instruction + 4
     */
    *pc -= 0xa;
}
 
/* 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 void arm7tdmi_read_core_regs(struct target *target,
        uint32_t mask, uint32_t *core_regs[16])
{
    int i;
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* STMIA r0-15, [r0] at debug speed
     * register values will start to appear on 4th DCLK
     */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_STMIA(0, mask & 0xffff, 0, 0), 0);
 
    /* fetch NOP, STM in DECODE stage */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, STM in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
 
    for (i = 0; i <= 15; i++) {
        if (mask & (1 << i))
            /* nothing fetched, STM still in EXECUTE (1 + i cycle) */
            arm7tdmi_clock_data_in(jtag_info, core_regs[i]);
    }
}
 
static void arm7tdmi_read_core_regs_target_buffer(struct target *target,
        uint32_t mask, void *buffer, int size)
{
    int i;
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
    int be = (target->endianness == TARGET_BIG_ENDIAN) ? 1 : 0;
    uint32_t *buf_u32 = buffer;
    uint16_t *buf_u16 = buffer;
    uint8_t *buf_u8 = buffer;
 
    /* STMIA r0-15, [r0] at debug speed
     * register values will start to appear on 4th DCLK
     */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_STMIA(0, mask & 0xffff, 0, 0), 0);
 
    /* fetch NOP, STM in DECODE stage */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, STM in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
 
    for (i = 0; i <= 15; i++) {
        /* nothing fetched, STM still in EXECUTE (1 + i cycle), read databus */
        if (mask & (1 << i)) {
            switch (size) {
                case 4:
                    arm7tdmi_clock_data_in_endianness(jtag_info, buf_u32++, 4, be);
                    break;
                case 2:
                    arm7tdmi_clock_data_in_endianness(jtag_info, buf_u16++, 2, be);
                    break;
                case 1:
                    arm7tdmi_clock_data_in_endianness(jtag_info, buf_u8++, 1, be);
                    break;
            }
        }
    }
}
 
static void arm7tdmi_read_xpsr(struct target *target, uint32_t *xpsr, int spsr)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* MRS r0, cpsr */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_MRS(0, spsr & 1), 0);
 
    /* STR r0, [r15] */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_STR(0, 15), 0);
    /* fetch NOP, STR in DECODE stage */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, STR in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, STR still in EXECUTE (2nd cycle) */
    arm7tdmi_clock_data_in(jtag_info, xpsr);
}
 
static void arm7tdmi_write_xpsr(struct target *target, uint32_t xpsr, int spsr)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    LOG_DEBUG("xpsr: %8.8" PRIx32 ", spsr: %i", xpsr, spsr);
 
    /* MSR1 fetched */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_MSR_IM(xpsr & 0xff, 0, 1, spsr), 0);
    /* MSR2 fetched, MSR1 in DECODE */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_MSR_IM((xpsr & 0xff00) >> 8, 0xc, 2, spsr), 0);
    /* MSR3 fetched, MSR1 in EXECUTE (1), MSR2 in DECODE */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_MSR_IM((xpsr & 0xff0000) >> 16, 0x8, 4, spsr), 0);
    /* nothing fetched, MSR1 in EXECUTE (2) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* MSR4 fetched, MSR2 in EXECUTE (1), MSR3 in DECODE */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_MSR_IM((xpsr & 0xff000000) >> 24, 0x4, 8, spsr), 0);
    /* nothing fetched, MSR2 in EXECUTE (2) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* NOP fetched, MSR3 in EXECUTE (1), MSR4 in DECODE */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, MSR3 in EXECUTE (2) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* NOP fetched, MSR4 in EXECUTE (1) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, MSR4 in EXECUTE (2) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
}
 
static void arm7tdmi_write_xpsr_im8(struct target *target,
        uint8_t xpsr_im, int rot, int spsr)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    LOG_DEBUG("xpsr_im: %2.2x, rot: %i, spsr: %i", xpsr_im, rot, spsr);
 
    /* MSR fetched */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_MSR_IM(xpsr_im, rot, 1, spsr), 0);
    /* NOP fetched, MSR in DECODE */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* NOP fetched, MSR in EXECUTE (1) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, MSR in EXECUTE (2) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
}
 
static void arm7tdmi_write_core_regs(struct target *target,
        uint32_t mask, uint32_t core_regs[16])
{
    int i;
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* LDMIA r0-15, [r0] at debug speed
    * register values will start to appear on 4th DCLK
    */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_LDMIA(0, mask & 0xffff, 0, 0), 0);
 
    /* fetch NOP, LDM in DECODE stage */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, LDM in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
 
    for (i = 0; i <= 15; i++) {
        if (mask & (1 << i))
            /* nothing fetched, LDM still in EXECUTE (1 + i cycle) */
            arm7tdmi_clock_out_inner(jtag_info, core_regs[i], 0);
    }
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
}
 
static void arm7tdmi_load_word_regs(struct target *target, uint32_t mask)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* put system-speed load-multiple into the pipeline */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_LDMIA(0, mask & 0xffff, 0, 1), 0);
}
 
static void arm7tdmi_load_hword_reg(struct target *target, int num)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* put system-speed load half-word into the pipeline */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_LDRH_IP(num, 0), 0);
}
 
static void arm7tdmi_load_byte_reg(struct target *target, int num)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* put system-speed load byte into the pipeline */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_LDRB_IP(num, 0), 0);
}
 
static void arm7tdmi_store_word_regs(struct target *target, uint32_t mask)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* put system-speed store-multiple into the pipeline */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_STMIA(0, mask, 0, 1), 0);
}
 
static void arm7tdmi_store_hword_reg(struct target *target, int num)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* put system-speed store half-word into the pipeline */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_STRH_IP(num, 0), 0);
}
 
static void arm7tdmi_store_byte_reg(struct target *target, int num)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* put system-speed store byte into the pipeline */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_STRB_IP(num, 0), 0);
}
 
static void arm7tdmi_write_pc(struct target *target, uint32_t pc)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    /* LDMIA r0-15, [r0] at debug speed
     * register values will start to appear on 4th DCLK
     */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_LDMIA(0, 0x8000, 0, 0), 0);
    /* fetch NOP, LDM in DECODE stage */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, LDM in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, LDM in EXECUTE stage (1st cycle) load register */
    arm7tdmi_clock_out_inner(jtag_info, pc, 0);
    /* nothing fetched, LDM in EXECUTE stage (2nd cycle) load register */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, LDM in EXECUTE stage (3rd cycle) load register */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, LDM in EXECUTE stage (4th cycle) */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, LDM in EXECUTE stage (5th cycle) */
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_NOP, 0);
}
 
static void arm7tdmi_branch_resume(struct target *target)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
 
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 1);
    arm7tdmi_clock_out_inner(jtag_info, ARMV4_5_B(0xfffffa, 0), 0);
}
 
static void arm7tdmi_branch_resume_thumb(struct target *target)
{
    struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
    struct arm *arm = &arm7_9->arm;
    struct arm_jtag *jtag_info = &arm7_9->jtag_info;
    struct reg *dbg_stat = &arm7_9->eice_cache->reg_list[EICE_DBG_STAT];
 
    LOG_DEBUG("-");
 
    /* LDMIA r0, [r0] at debug speed
     * register values will start to appear on 4th DCLK
     */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_LDMIA(0, 0x1, 0, 0), 0);
 
    /* fetch NOP, LDM in DECODE stage */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* fetch NOP, LDM in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
    /* nothing fetched, LDM in EXECUTE stage (2nd cycle) */
    arm7tdmi_clock_out(jtag_info, buf_get_u32(arm->pc->value, 0, 32) | 1, 0);
    /* nothing fetched, LDM in EXECUTE stage (3rd cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
 
    /* Branch and eXchange */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_BX(0), 0);
 
    embeddedice_read_reg(dbg_stat);
 
    /* fetch NOP, BX in DECODE stage */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
 
    /* target is now in Thumb state */
    embeddedice_read_reg(dbg_stat);
 
    /* fetch NOP, BX in EXECUTE stage (1st cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_NOP, 0);
 
    /* target is now in Thumb state */
    embeddedice_read_reg(dbg_stat);
 
    /* load r0 value */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_LDR_PCREL(0), 0);
    /* fetch NOP, LDR in Decode */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    /* fetch NOP, LDR in Execute */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    /* nothing fetched, LDR in EXECUTE stage (2nd cycle) */
    arm7tdmi_clock_out(jtag_info, buf_get_u32(arm->core_cache->reg_list[0].value, 0, 32), 0);
    /* nothing fetched, LDR in EXECUTE stage (3rd cycle) */
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
 
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 0);
 
    embeddedice_read_reg(dbg_stat);
 
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_NOP, 1);
    arm7tdmi_clock_out(jtag_info, ARMV4_5_T_B(0x7f8), 0);
}
 
static void arm7tdmi_build_reg_cache(struct target *target)
{
    struct reg_cache **cache_p = register_get_last_cache_p(&target->reg_cache);
    struct arm *arm = target_to_arm(target);
 
    (*cache_p) = arm_build_reg_cache(target, arm);
}
 
static void arm7tdmi_free_reg_cache(struct target *target)
{
    struct arm *arm = target_to_arm(target);
 
    arm_free_reg_cache(arm);
}
 
int arm7tdmi_init_target(struct command_context *cmd_ctx, struct target *target)
{
    arm7tdmi_build_reg_cache(target);
    arm_semihosting_init(target);
    return ERROR_OK;
}
 
void arm7tdmi_deinit_target(struct target *target)
{
    arm7tdmi_free_reg_cache(target);
}
 
int arm7tdmi_init_arch_info(struct target *target,
        struct arm7_9_common *arm7_9, struct jtag_tap *tap)
{
    /* prepare JTAG information for the new target */
    arm7_9->jtag_info.tap = tap;
    arm7_9->jtag_info.scann_size = 4;
 
    /* register arch-specific functions */
    arm7_9->examine_debug_reason = arm7tdmi_examine_debug_reason;
    arm7_9->change_to_arm = arm7tdmi_change_to_arm;
    arm7_9->read_core_regs = arm7tdmi_read_core_regs;
    arm7_9->read_core_regs_target_buffer = arm7tdmi_read_core_regs_target_buffer;
    arm7_9->read_xpsr = arm7tdmi_read_xpsr;
 
    arm7_9->write_xpsr = arm7tdmi_write_xpsr;
    arm7_9->write_xpsr_im8 = arm7tdmi_write_xpsr_im8;
    arm7_9->write_core_regs = arm7tdmi_write_core_regs;
 
    arm7_9->load_word_regs = arm7tdmi_load_word_regs;
    arm7_9->load_hword_reg = arm7tdmi_load_hword_reg;
    arm7_9->load_byte_reg = arm7tdmi_load_byte_reg;
 
    arm7_9->store_word_regs = arm7tdmi_store_word_regs;
    arm7_9->store_hword_reg = arm7tdmi_store_hword_reg;
    arm7_9->store_byte_reg = arm7tdmi_store_byte_reg;
 
    arm7_9->write_pc = arm7tdmi_write_pc;
    arm7_9->branch_resume = arm7tdmi_branch_resume;
    arm7_9->branch_resume_thumb = arm7tdmi_branch_resume_thumb;
 
    arm7_9->enable_single_step = arm7_9_enable_eice_step;
    arm7_9->disable_single_step = arm7_9_disable_eice_step;
 
    arm7_9->write_memory = arm7_9_write_memory;
    arm7_9->bulk_write_memory = arm7_9_bulk_write_memory;
 
    arm7_9->post_debug_entry = NULL;
 
    arm7_9->pre_restore_context = NULL;
 
    /* initialize arch-specific breakpoint handling */
    arm7_9->arm_bkpt = 0xdeeedeee;
    arm7_9->thumb_bkpt = 0xdeee;
 
    arm7_9->dbgreq_adjust_pc = 2;
 
    arm7_9_init_arch_info(target, arm7_9);
 
    return ERROR_OK;
}
 
static int arm7tdmi_target_create(struct target *target, Jim_Interp *interp)
{
    struct arm7_9_common *arm7_9;
 
    arm7_9 = calloc(1, sizeof(struct arm7_9_common));
    arm7tdmi_init_arch_info(target, arm7_9, target->tap);
    arm7_9->arm.arch = ARM_ARCH_V4;
 
    return ERROR_OK;
}
 
struct target_type arm7tdmi_target = {
    .name = "arm7tdmi",
 
    .poll = arm7_9_poll,
    .arch_state = arm_arch_state,
 
    .target_request_data = arm7_9_target_request_data,
 
    .halt = arm7_9_halt,
    .resume = arm7_9_resume,
    .step = arm7_9_step,
 
    .assert_reset = arm7_9_assert_reset,
    .deassert_reset = arm7_9_deassert_reset,
    .soft_reset_halt = arm7_9_soft_reset_halt,
 
    .get_gdb_arch = arm_get_gdb_arch,
    .get_gdb_reg_list = arm_get_gdb_reg_list,
 
    .read_memory = arm7_9_read_memory,
    .write_memory = arm7_9_write_memory_opt,
 
    .checksum_memory = arm_checksum_memory,
    .blank_check_memory = arm_blank_check_memory,
 
    .run_algorithm = armv4_5_run_algorithm,
 
    .add_breakpoint = arm7_9_add_breakpoint,
    .remove_breakpoint = arm7_9_remove_breakpoint,
    .add_watchpoint = arm7_9_add_watchpoint,
    .remove_watchpoint = arm7_9_remove_watchpoint,
 
    .commands  = arm7_9_command_handlers,
    .target_create  = arm7tdmi_target_create,
    .init_target = arm7tdmi_init_target,
    .deinit_target = arm7tdmi_deinit_target,
    .examine = arm7_9_examine,
    .check_reset = arm7_9_check_reset,
};