jtag: linuxgpiod: drop extra parenthesis

[openocd.git] / src / target / arm7tdmi.c

/***************************************************************************
 *   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                                               *
 *                                                                         *
 *   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, see <http://www.gnu.org/licenses/>. *
 ***************************************************************************/

#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;
}

/** Holds methods for ARM7TDMI targets. */
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,
};