[fw/openocd] / src / target / arm7_9_common.c

/* SPDX-License-Identifier: GPL-2.0-or-later */

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007-2010 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   Copyright (C) 2008 by Hongtao Zheng                                   *
 *   hontor@126.com                                                        *
 *                                                                         *
 *   Copyright (C) 2009 by David Brownell                                  *
 ***************************************************************************/

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

#include "breakpoints.h"
#include "embeddedice.h"
#include "target_request.h"
#include "etm.h"
#include <helper/time_support.h>
#include "arm_simulator.h"
#include "arm_semihosting.h"
#include "algorithm.h"
#include "register.h"
#include "armv4_5.h"

/**
 * @file
 * Hold common code supporting the ARM7 and ARM9 core generations.
 *
 * While the ARM core implementations evolved substantially during these
 * two generations, they look quite similar from the JTAG perspective.
 * Both have similar debug facilities, based on the same two scan chains
 * providing access to the core and to an EmbeddedICE module.  Both can
 * support similar ETM and ETB modules, for tracing.  And both expose
 * what could be viewed as "ARM Classic", with multiple processor modes,
 * shadowed registers, and support for the Thumb instruction set.
 *
 * Processor differences include things like presence or absence of MMU
 * and cache, pipeline sizes, use of a modified Harvard Architecture
 * (with separate instruction and data buses from the CPU), support
 * for cpu clock gating during idle, and more.
 */

static int arm7_9_debug_entry(struct target *target);

/**
 * Clear watchpoints for an ARM7/9 target.
 *
 * @param arm7_9 Pointer to the common struct for an ARM7/9 target
 * @return JTAG error status after executing queue
 */
static int arm7_9_clear_watchpoints(struct arm7_9_common *arm7_9)
{
        LOG_DEBUG("-");
        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], 0x0);
        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE], 0x0);
        arm7_9->sw_breakpoint_count = 0;
        arm7_9->sw_breakpoints_added = 0;
        arm7_9->wp0_used = 0;
        arm7_9->wp1_used = arm7_9->wp1_used_default;
        arm7_9->wp_available = arm7_9->wp_available_max;

        return jtag_execute_queue();
}

/**
 * Assign a watchpoint to one of the two available hardware comparators in an
 * ARM7 or ARM9 target.
 *
 * @param arm7_9 Pointer to the common struct for an ARM7/9 target
 * @param breakpoint Pointer to the breakpoint to be used as a watchpoint
 */
static void arm7_9_assign_wp(struct arm7_9_common *arm7_9, struct breakpoint *breakpoint)
{
        if (!arm7_9->wp0_used) {
                arm7_9->wp0_used = 1;
                breakpoint_hw_set(breakpoint, 0);
                arm7_9->wp_available--;
        } else if (!arm7_9->wp1_used) {
                arm7_9->wp1_used = 1;
                breakpoint_hw_set(breakpoint, 1);
                arm7_9->wp_available--;
        } else {
                LOG_ERROR("BUG: no hardware comparator available");
        }

        LOG_DEBUG("BPID: %" PRIu32 " (0x%08" TARGET_PRIxADDR ") using hw wp: %u",
                        breakpoint->unique_id,
                        breakpoint->address,
                        breakpoint->number);
}

/**
 * Setup an ARM7/9 target's embedded ICE registers for software breakpoints.
 *
 * @param arm7_9 Pointer to common struct for ARM7/9 targets
 * @return Error codes if there is a problem finding a watchpoint or the result
 * of executing the JTAG queue
 */
static int arm7_9_set_software_breakpoints(struct arm7_9_common *arm7_9)
{
        if (arm7_9->sw_breakpoints_added)
                return ERROR_OK;
        if (arm7_9->wp_available < 1) {
                LOG_WARNING("can't enable sw breakpoints with no watchpoint unit available");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }
        arm7_9->wp_available--;

        /* pick a breakpoint unit */
        if (!arm7_9->wp0_used) {
                arm7_9->sw_breakpoints_added = 1;
                arm7_9->wp0_used = 3;
        } else if (!arm7_9->wp1_used) {
                arm7_9->sw_breakpoints_added = 2;
                arm7_9->wp1_used = 3;
        } else {
                LOG_ERROR("BUG: both watchpoints used, but wp_available >= 1");
                return ERROR_FAIL;
        }

        if (arm7_9->sw_breakpoints_added == 1) {
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_VALUE], arm7_9->arm_bkpt);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK], 0x0);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], 0xffffffffu);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK], ~EICE_W_CTRL_NOPC & 0xff);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], EICE_W_CTRL_ENABLE);
        } else if (arm7_9->sw_breakpoints_added == 2) {
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_VALUE], arm7_9->arm_bkpt);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_MASK], 0x0);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_MASK], 0xffffffffu);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_MASK], ~EICE_W_CTRL_NOPC & 0xff);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE], EICE_W_CTRL_ENABLE);
        } else {
                LOG_ERROR("BUG: both watchpoints used, but wp_available >= 1");
                return ERROR_FAIL;
        }
        LOG_DEBUG("SW BP using hw wp: %d",
                arm7_9->sw_breakpoints_added);

        return jtag_execute_queue();
}

/**
 * Setup the common pieces for an ARM7/9 target after reset or on startup.
 *
 * @param target Pointer to an ARM7/9 target to setup
 * @return Result of clearing the watchpoints on the target
 */
static int arm7_9_setup(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        return arm7_9_clear_watchpoints(arm7_9);
}

/**
 * Set either a hardware or software breakpoint on an ARM7/9 target.  The
 * breakpoint is set up even if it is already set.  Some actions, e.g. reset,
 * might have erased the values in Embedded ICE.
 *
 * @param target Pointer to the target device to set the breakpoints on
 * @param breakpoint Pointer to the breakpoint to be set
 * @return For hardware breakpoints, this is the result of executing the JTAG
 * queue.  For software breakpoints, this will be the status of the
 * required memory reads and writes
 */
static int arm7_9_set_breakpoint(struct target *target, struct breakpoint *breakpoint)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        int retval = ERROR_OK;

        LOG_DEBUG("BPID: %" PRIu32 ", Address: 0x%08" TARGET_PRIxADDR ", Type: %d",
                breakpoint->unique_id,
                breakpoint->address,
                breakpoint->type);

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (breakpoint->type == BKPT_HARD) {
                /* either an ARM (4 byte) or Thumb (2 byte) breakpoint */
                uint32_t mask = (breakpoint->length == 4) ? 0x3u : 0x1u;

                /* reassign a hw breakpoint */
                if (!breakpoint->is_set)
                        arm7_9_assign_wp(arm7_9, breakpoint);

                if (breakpoint->number == 0) {
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_VALUE], breakpoint->address);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], mask);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK], 0xffffffffu);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK], ~EICE_W_CTRL_NOPC & 0xff);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], EICE_W_CTRL_ENABLE);
                } else if (breakpoint->number == 1) {
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_VALUE], breakpoint->address);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_MASK], mask);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_MASK], 0xffffffffu);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_MASK], ~EICE_W_CTRL_NOPC & 0xff);
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE], EICE_W_CTRL_ENABLE);
                } else {
                        LOG_ERROR("BUG: no hardware comparator available");
                        return ERROR_OK;
                }

                retval = jtag_execute_queue();
        } else if (breakpoint->type == BKPT_SOFT) {
                /* did we already set this breakpoint? */
                if (breakpoint->is_set)
                        return ERROR_OK;

                if (breakpoint->length == 4) {
                        uint32_t verify = 0xffffffff;
                        /* keep the original instruction in target endianness */
                        retval = target_read_memory(target, breakpoint->address, 4, 1, breakpoint->orig_instr);
                        if (retval != ERROR_OK)
                                return retval;
                        /* write the breakpoint instruction in target
                         * endianness (arm7_9->arm_bkpt is host endian) */
                        retval = target_write_u32(target, breakpoint->address, arm7_9->arm_bkpt);
                        if (retval != ERROR_OK)
                                return retval;

                        retval = target_read_u32(target, breakpoint->address, &verify);
                        if (retval != ERROR_OK)
                                return retval;
                        if (verify != arm7_9->arm_bkpt) {
                                LOG_ERROR("Unable to set 32 bit software breakpoint at address %08" TARGET_PRIxADDR
                                                " - check that memory is read/writable", breakpoint->address);
                                return ERROR_OK;
                        }
                } else {
                        uint16_t verify = 0xffff;
                        /* keep the original instruction in target endianness */
                        retval = target_read_memory(target, breakpoint->address, 2, 1, breakpoint->orig_instr);
                        if (retval != ERROR_OK)
                                return retval;
                        /* write the breakpoint instruction in target
                         * endianness (arm7_9->thumb_bkpt is host endian) */
                        retval = target_write_u16(target, breakpoint->address, arm7_9->thumb_bkpt);
                        if (retval != ERROR_OK)
                                return retval;

                        retval = target_read_u16(target, breakpoint->address, &verify);
                        if (retval != ERROR_OK)
                                return retval;
                        if (verify != arm7_9->thumb_bkpt) {
                                LOG_ERROR("Unable to set thumb software breakpoint at address %08" TARGET_PRIxADDR
                                                " - check that memory is read/writable", breakpoint->address);
                                return ERROR_OK;
                        }
                }

                retval = arm7_9_set_software_breakpoints(arm7_9);
                if (retval != ERROR_OK)
                        return retval;

                arm7_9->sw_breakpoint_count++;

                breakpoint->is_set = true;
        }

        return retval;
}

/**
 * Unsets an existing breakpoint on an ARM7/9 target.  If it is a hardware
 * breakpoint, the watchpoint used will be freed and the Embedded ICE registers
 * will be updated.  Otherwise, the software breakpoint will be restored to its
 * original instruction if it hasn't already been modified.
 *
 * @param target Pointer to ARM7/9 target to unset the breakpoint from
 * @param breakpoint Pointer to breakpoint to be unset
 * @return For hardware breakpoints, this is the result of executing the JTAG
 * queue.  For software breakpoints, this will be the status of the
 * required memory reads and writes
 */
static int arm7_9_unset_breakpoint(struct target *target, struct breakpoint *breakpoint)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        LOG_DEBUG("BPID: %" PRIu32 ", Address: 0x%08" TARGET_PRIxADDR,
                breakpoint->unique_id,
                breakpoint->address);

        if (!breakpoint->is_set) {
                LOG_WARNING("breakpoint not set");
                return ERROR_OK;
        }

        if (breakpoint->type == BKPT_HARD) {
                LOG_DEBUG("BPID: %" PRIu32 " Releasing hw wp: %d",
                        breakpoint->unique_id,
                        breakpoint->is_set);
                if (breakpoint->number == 0) {
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], 0x0);
                        arm7_9->wp0_used = 0;
                        arm7_9->wp_available++;
                } else if (breakpoint->number == 1) {
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE], 0x0);
                        arm7_9->wp1_used = 0;
                        arm7_9->wp_available++;
                }
                retval = jtag_execute_queue();
                breakpoint->is_set = false;
        } else {
                /* restore original instruction (kept in target endianness) */
                if (breakpoint->length == 4) {
                        uint32_t current_instr;
                        /* check that user program as not modified breakpoint instruction */
                        retval = target_read_memory(target,
                                        breakpoint->address, 4, 1, (uint8_t *)&current_instr);
                        if (retval != ERROR_OK)
                                return retval;
                        current_instr = target_buffer_get_u32(target, (uint8_t *)&current_instr);
                        if (current_instr == arm7_9->arm_bkpt) {
                                retval = target_write_memory(target,
                                                breakpoint->address, 4, 1, breakpoint->orig_instr);
                                if (retval != ERROR_OK)
                                        return retval;
                        }

                } else {
                        uint16_t current_instr;
                        /* check that user program as not modified breakpoint instruction */
                        retval = target_read_memory(target,
                                        breakpoint->address, 2, 1, (uint8_t *)&current_instr);
                        if (retval != ERROR_OK)
                                return retval;
                        current_instr = target_buffer_get_u16(target, (uint8_t *)&current_instr);
                        if (current_instr == arm7_9->thumb_bkpt) {
                                retval = target_write_memory(target,
                                                breakpoint->address, 2, 1, breakpoint->orig_instr);
                                if (retval != ERROR_OK)
                                        return retval;
                        }
                }

                if (--arm7_9->sw_breakpoint_count == 0) {
                        /* We have removed the last sw breakpoint, clear the hw breakpoint we used
                         *to implement it */
                        if (arm7_9->sw_breakpoints_added == 1)
                                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[
                                                EICE_W0_CONTROL_VALUE], 0);
                        else if (arm7_9->sw_breakpoints_added == 2)
                                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[
                                                EICE_W1_CONTROL_VALUE], 0);
                }

                breakpoint->is_set = false;
        }

        return retval;
}

/**
 * Add a breakpoint to an ARM7/9 target.  This makes sure that there are no
 * dangling breakpoints and that the desired breakpoint can be added.
 *
 * @param target Pointer to the target ARM7/9 device to add a breakpoint to
 * @param breakpoint Pointer to the breakpoint to be added
 * @return An error status if there is a problem adding the breakpoint or the
 * result of setting the breakpoint
 */
int arm7_9_add_breakpoint(struct target *target, struct breakpoint *breakpoint)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (arm7_9->breakpoint_count == 0) {
                /* make sure we don't have any dangling breakpoints. This is vital upon
                 * GDB connect/disconnect
                 */
                arm7_9_clear_watchpoints(arm7_9);
        }

        if ((breakpoint->type == BKPT_HARD) && (arm7_9->wp_available < 1)) {
                LOG_INFO("no watchpoint unit available for hardware breakpoint");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }

        if ((breakpoint->length != 2) && (breakpoint->length != 4)) {
                LOG_INFO("only breakpoints of two (Thumb) or four (ARM) bytes length supported");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }

        if (breakpoint->type == BKPT_HARD)
                arm7_9_assign_wp(arm7_9, breakpoint);

        arm7_9->breakpoint_count++;

        return arm7_9_set_breakpoint(target, breakpoint);
}

/**
 * Removes a breakpoint from an ARM7/9 target.  This will make sure there are no
 * dangling breakpoints and updates available watchpoints if it is a hardware
 * breakpoint.
 *
 * @param target Pointer to the target to have a breakpoint removed
 * @param breakpoint Pointer to the breakpoint to be removed
 * @return Error status if there was a problem unsetting the breakpoint or the
 * watchpoints could not be cleared
 */
int arm7_9_remove_breakpoint(struct target *target, struct breakpoint *breakpoint)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        retval = arm7_9_unset_breakpoint(target, breakpoint);
        if (retval != ERROR_OK)
                return retval;

        if (breakpoint->type == BKPT_HARD)
                arm7_9->wp_available++;

        arm7_9->breakpoint_count--;
        if (arm7_9->breakpoint_count == 0) {
                /* make sure we don't have any dangling breakpoints */
                retval = arm7_9_clear_watchpoints(arm7_9);
                if (retval != ERROR_OK)
                        return retval;
        }

        return ERROR_OK;
}

/**
 * Sets a watchpoint for an ARM7/9 target in one of the watchpoint units.  It is
 * considered a bug to call this function when there are no available watchpoint
 * units.
 *
 * @param target Pointer to an ARM7/9 target to set a watchpoint on
 * @param watchpoint Pointer to the watchpoint to be set
 * @return Error status if watchpoint set fails or the result of executing the
 * JTAG queue
 */
static int arm7_9_set_watchpoint(struct target *target, struct watchpoint *watchpoint)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        int rw_mask = 1;
        uint32_t mask;

        mask = watchpoint->length - 1;

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (watchpoint->rw == WPT_ACCESS)
                rw_mask = 0;
        else
                rw_mask = 1;

        if (!arm7_9->wp0_used) {
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_VALUE],
                        watchpoint->address);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], mask);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK],
                        watchpoint->mask);
                if (watchpoint->mask != 0xffffffffu)
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_VALUE],
                                watchpoint->value);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK],
                        0xff & ~EICE_W_CTRL_NOPC & ~rw_mask);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE],
                        EICE_W_CTRL_ENABLE | EICE_W_CTRL_NOPC | (watchpoint->rw & 1));

                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                watchpoint_set(watchpoint, 1);
                arm7_9->wp0_used = 2;
        } else if (!arm7_9->wp1_used) {
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_VALUE],
                        watchpoint->address);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_MASK], mask);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_MASK],
                        watchpoint->mask);
                if (watchpoint->mask != 0xffffffffu)
                        embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_VALUE],
                                watchpoint->value);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_MASK],
                        0xff & ~EICE_W_CTRL_NOPC & ~rw_mask);
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE],
                        EICE_W_CTRL_ENABLE | EICE_W_CTRL_NOPC | (watchpoint->rw & 1));

                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                watchpoint_set(watchpoint, 2);
                arm7_9->wp1_used = 2;
        } else {
                LOG_ERROR("BUG: no hardware comparator available");
                return ERROR_OK;
        }

        return ERROR_OK;
}

/**
 * Unset an existing watchpoint and clear the used watchpoint unit.
 *
 * @param target Pointer to the target to have the watchpoint removed
 * @param watchpoint Pointer to the watchpoint to be removed
 * @return Error status while trying to unset the watchpoint or the result of
 *         executing the JTAG queue
 */
static int arm7_9_unset_watchpoint(struct target *target, struct watchpoint *watchpoint)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (!watchpoint->is_set) {
                LOG_WARNING("breakpoint not set");
                return ERROR_OK;
        }

        if (watchpoint->number == 1) {
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], 0x0);
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                arm7_9->wp0_used = 0;
        } else if (watchpoint->number == 2) {
                embeddedice_set_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE], 0x0);
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                arm7_9->wp1_used = 0;
        }
        watchpoint->is_set = false;

        return ERROR_OK;
}

/**
 * Add a watchpoint to an ARM7/9 target.  If there are no watchpoint units
 * available, an error response is returned.
 *
 * @param target Pointer to the ARM7/9 target to add a watchpoint to
 * @param watchpoint Pointer to the watchpoint to be added
 * @return Error status while trying to add the watchpoint
 */
int arm7_9_add_watchpoint(struct target *target, struct watchpoint *watchpoint)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (arm7_9->wp_available < 1)
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;

        if ((watchpoint->length != 1) && (watchpoint->length != 2) && (watchpoint->length != 4))
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;

        arm7_9->wp_available--;

        return ERROR_OK;
}

/**
 * Remove a watchpoint from an ARM7/9 target.  The watchpoint will be unset and
 * the used watchpoint unit will be reopened.
 *
 * @param target Pointer to the target to remove a watchpoint from
 * @param watchpoint Pointer to the watchpoint to be removed
 * @return Result of trying to unset the watchpoint
 */
int arm7_9_remove_watchpoint(struct target *target, struct watchpoint *watchpoint)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (watchpoint->is_set) {
                retval = arm7_9_unset_watchpoint(target, watchpoint);
                if (retval != ERROR_OK)
                        return retval;
        }

        arm7_9->wp_available++;

        return ERROR_OK;
}

/**
 * Restarts the target by sending a RESTART instruction and moving the JTAG
 * state to IDLE.  This includes a timeout waiting for DBGACK and SYSCOMP to be
 * asserted by the processor.
 *
 * @param target Pointer to target to issue commands to
 * @return Error status if there is a timeout or a problem while executing the
 * JTAG queue
 */
int arm7_9_execute_sys_speed(struct target *target)
{
        int retval;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        struct reg *dbg_stat = &arm7_9->eice_cache->reg_list[EICE_DBG_STAT];

        /* set RESTART instruction */
        if (arm7_9->need_bypass_before_restart) {
                arm7_9->need_bypass_before_restart = 0;
                retval = arm_jtag_set_instr(jtag_info->tap, 0xf, NULL, TAP_IDLE);
                if (retval != ERROR_OK)
                        return retval;
        }
        retval = arm_jtag_set_instr(jtag_info->tap, 0x4, NULL, TAP_IDLE);
        if (retval != ERROR_OK)
                return retval;

        int64_t then = timeval_ms();
        bool timeout;
        while (!(timeout = ((timeval_ms()-then) > 1000))) {
                /* read debug status register */
                embeddedice_read_reg(dbg_stat);
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                if ((buf_get_u32(dbg_stat->value, EICE_DBG_STATUS_DBGACK, 1))
                                && (buf_get_u32(dbg_stat->value, EICE_DBG_STATUS_SYSCOMP, 1)))
                        break;
                if (debug_level >= 3)
                        alive_sleep(100);
                else
                        keep_alive();
        }
        if (timeout) {
                LOG_ERROR("timeout waiting for SYSCOMP & DBGACK, last DBG_STATUS: %" PRIx32 "",
                        buf_get_u32(dbg_stat->value, 0, dbg_stat->size));
                return ERROR_TARGET_TIMEOUT;
        }

        return ERROR_OK;
}

/**
 * Restarts the target by sending a RESTART instruction and moving the JTAG
 * state to IDLE.  This validates that DBGACK and SYSCOMP are set without
 * waiting until they are.
 *
 * @param target Pointer to the target to issue commands to
 * @return Always ERROR_OK
 */
static int arm7_9_execute_fast_sys_speed(struct target *target)
{
        static int set;
        static uint8_t check_value[4], check_mask[4];

        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        struct reg *dbg_stat = &arm7_9->eice_cache->reg_list[EICE_DBG_STAT];
        int retval;

        /* set RESTART instruction */
        if (arm7_9->need_bypass_before_restart) {
                arm7_9->need_bypass_before_restart = 0;
                retval = arm_jtag_set_instr(jtag_info->tap, 0xf, NULL, TAP_IDLE);
                if (retval != ERROR_OK)
                        return retval;
        }
        retval = arm_jtag_set_instr(jtag_info->tap, 0x4, NULL, TAP_IDLE);
        if (retval != ERROR_OK)
                return retval;

        if (!set) {
                /* check for DBGACK and SYSCOMP set (others don't care) */

                /* NB! These are constants that must be available until after next jtag_execute() and
                 * we evaluate the values upon first execution in lieu of setting up these constants
                 * during early setup.
                 * */
                buf_set_u32(check_value, 0, 32, 0x9);
                buf_set_u32(check_mask, 0, 32, 0x9);
                set = 1;
        }

        /* read debug status register */
        embeddedice_read_reg_w_check(dbg_stat, check_value, check_mask);

        return ERROR_OK;
}

/**
 * Get some data from the ARM7/9 target.
 *
 * @param target Pointer to the ARM7/9 target to read data from
 * @param size The number of 32bit words to be read
 * @param buffer Pointer to the buffer that will hold the data
 * @return The result of receiving data from the Embedded ICE unit
 */
int arm7_9_target_request_data(struct target *target, uint32_t size, uint8_t *buffer)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        uint32_t *data;
        int retval = ERROR_OK;
        uint32_t i;

        data = malloc(size * (sizeof(uint32_t)));

        retval = embeddedice_receive(jtag_info, data, size);

        /* return the 32-bit ints in the 8-bit array */
        for (i = 0; i < size; i++)
                h_u32_to_le(buffer + (i * 4), data[i]);

        free(data);

        return retval;
}

/**
 * Handles requests to an ARM7/9 target.  If debug messaging is enabled, the
 * target is running and the DCC control register has the W bit high, this will
 * execute the request on the target.
 *
 * @param priv Void pointer expected to be a struct target pointer
 * @return ERROR_OK unless there are issues with the JTAG queue or when reading
 * from the Embedded ICE unit
 */
static int arm7_9_handle_target_request(void *priv)
{
        int retval = ERROR_OK;
        struct target *target = priv;
        if (!target_was_examined(target))
                return ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        struct reg *dcc_control = &arm7_9->eice_cache->reg_list[EICE_COMMS_CTRL];

        if (!target->dbg_msg_enabled)
                return ERROR_OK;

        if (target->state == TARGET_RUNNING) {
                /* read DCC control register */
                embeddedice_read_reg(dcc_control);
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;

                /* check W bit */
                if (buf_get_u32(dcc_control->value, 1, 1) == 1) {
                        uint32_t request;

                        retval = embeddedice_receive(jtag_info, &request, 1);
                        if (retval != ERROR_OK)
                                return retval;
                        retval = target_request(target, request);
                        if (retval != ERROR_OK)
                                return retval;
                }
        }

        return ERROR_OK;
}

/**
 * Polls an ARM7/9 target for its current status.  If DBGACK is set, the target
 * is manipulated to the right halted state based on its current state.  This is
 * what happens:
 *
 * <table>
 *   <tr><th > State</th><th > Action</th></tr>
 *   <tr><td > TARGET_RUNNING | TARGET_RESET</td>
 *     <td > Enters debug mode.  If TARGET_RESET, pc may be checked</td></tr>
 *   <tr><td > TARGET_UNKNOWN</td><td > Warning is logged</td></tr>
 *   <tr><td > TARGET_DEBUG_RUNNING</td><td > Enters debug mode</td></tr>
 *   <tr><td > TARGET_HALTED</td><td > Nothing</td></tr>
 * </table>
 *
 * If the target does not end up in the halted state, a warning is produced.  If
 * DBGACK is cleared, then the target is expected to either be running or
 * running in debug.
 *
 * @param target Pointer to the ARM7/9 target to poll
 * @return ERROR_OK or an error status if a command fails
 */
int arm7_9_poll(struct target *target)
{
        int retval;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct reg *dbg_stat = &arm7_9->eice_cache->reg_list[EICE_DBG_STAT];

        /* read debug status register */
        embeddedice_read_reg(dbg_stat);
        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
                return retval;

        if (buf_get_u32(dbg_stat->value, EICE_DBG_STATUS_DBGACK, 1)) {
                /* LOG_DEBUG("DBGACK set, dbg_state->value: 0x%x", buf_get_u32(dbg_stat->value, 0, *32));*/
                if (target->state == TARGET_UNKNOWN) {
                        /* Starting OpenOCD with target in debug-halt */
                        target->state = TARGET_RUNNING;
                        LOG_DEBUG("DBGACK already set during server startup.");
                }
                if ((target->state == TARGET_RUNNING) || (target->state == TARGET_RESET)) {
                        target->state = TARGET_HALTED;

                        retval = arm7_9_debug_entry(target);
                        if (retval != ERROR_OK)
                                return retval;

                        if (arm_semihosting(target, &retval) != 0)
                                return retval;

                        retval = target_call_event_callbacks(target, TARGET_EVENT_HALTED);
                        if (retval != ERROR_OK)
                                return retval;
                }
                if (target->state == TARGET_DEBUG_RUNNING) {
                        target->state = TARGET_HALTED;
                        retval = arm7_9_debug_entry(target);
                        if (retval != ERROR_OK)
                                return retval;

                        retval = target_call_event_callbacks(target, TARGET_EVENT_DEBUG_HALTED);
                        if (retval != ERROR_OK)
                                return retval;
                }
                if (target->state != TARGET_HALTED)
                        LOG_WARNING(
                                "DBGACK set, but the target did not end up in the halted state %d",
                                target->state);
        } else {
                if (target->state != TARGET_DEBUG_RUNNING)
                        target->state = TARGET_RUNNING;
        }

        return ERROR_OK;
}

/**
 * Asserts the reset (SRST) on an ARM7/9 target.  Some -S targets (ARM966E-S in
 * the STR912 isn't affected, ARM926EJ-S in the LPC3180 and AT91SAM9260 is
 * affected) completely stop the JTAG clock while the core is held in reset
 * (SRST).  It isn't possible to program the halt condition once reset is
 * asserted, hence a hook that allows the target to set up its reset-halt
 * condition is setup prior to asserting reset.
 *
 * @param target Pointer to an ARM7/9 target to assert reset on
 * @return ERROR_FAIL if the JTAG device does not have SRST, otherwise ERROR_OK
 */
int arm7_9_assert_reset(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        enum reset_types jtag_reset_config = jtag_get_reset_config();
        bool use_event = false;

        /* TODO: apply hw reset signal in not examined state */
        if (!(target_was_examined(target))) {
                LOG_WARNING("Reset is not asserted because the target is not examined.");
                LOG_WARNING("Use a reset button or power cycle the target.");
                return ERROR_TARGET_NOT_EXAMINED;
        }

        LOG_DEBUG("target->state: %s", target_state_name(target));

        if (target_has_event_action(target, TARGET_EVENT_RESET_ASSERT))
                use_event = true;
        else if (!(jtag_reset_config & RESET_HAS_SRST)) {
                LOG_ERROR("%s: how to reset?", target_name(target));
                return ERROR_FAIL;
        }

        /* At this point trst has been asserted/deasserted once. We would
         * like to program EmbeddedICE while SRST is asserted, instead of
         * depending on SRST to leave that module alone.  However, many CPUs
         * gate the JTAG clock while SRST is asserted; or JTAG may need
         * clock stability guarantees (adaptive clocking might help).
         *
         * So we assume JTAG access during SRST is off the menu unless it's
         * been specifically enabled.
         */
        bool srst_asserted = false;

        if (!use_event && !(jtag_reset_config & RESET_SRST_PULLS_TRST)
                        && (jtag_reset_config & RESET_SRST_NO_GATING)) {
                jtag_add_reset(0, 1);
                srst_asserted = true;
        }

        if (target->reset_halt) {
                /*
                 * For targets that don't support communication while SRST is
                 * asserted, we need to set up the reset vector catch first.
                 *
                 * When we use TRST+SRST and that's equivalent to a power-up
                 * reset, these settings may well be reset anyway; so setting
                 * them here won't matter.
                 */
                if (arm7_9->has_vector_catch) {
                        /* program vector catch register to catch reset */
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_VEC_CATCH], 0x1);

                        /* extra runtest added as issues were found with
                         * certain ARM9 cores (maybe more) - AT91SAM9260
                         * and STR9
                         */
                        jtag_add_runtest(1, TAP_IDLE);
                } else {
                        /* program watchpoint unit to match on reset vector
                         * address
                         */
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_VALUE], 0x0);
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], 0x3);
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK], 0xffffffff);
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], EICE_W_CTRL_ENABLE);
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK], ~EICE_W_CTRL_NOPC & 0xff);
                }
        }

        if (use_event)
                target_handle_event(target, TARGET_EVENT_RESET_ASSERT);
        else {
                /* If we use SRST ... we'd like to issue just SRST, but the
                 * board or chip may be set up so we have to assert TRST as
                 * well.  On some chips that combination is equivalent to a
                 * power-up reset, and generally clobbers EICE state.
                 */
                if (jtag_reset_config & RESET_SRST_PULLS_TRST)
                        jtag_add_reset(1, 1);
                else if (!srst_asserted)
                        jtag_add_reset(0, 1);
                jtag_add_sleep(50000);
        }

        target->state = TARGET_RESET;
        register_cache_invalidate(arm7_9->arm.core_cache);

        /* REVISIT why isn't standard debug entry logic sufficient?? */
        if (target->reset_halt && (!(jtag_reset_config & RESET_SRST_PULLS_TRST) || use_event)) {
                /* debug entry was prepared above */
                target->debug_reason = DBG_REASON_DBGRQ;
        }

        return ERROR_OK;
}

/**
 * Deassert the reset (SRST) signal on an ARM7/9 target.  If SRST pulls TRST
 * and the target is being reset into a halt, a warning will be triggered
 * because it is not possible to reset into a halted mode in this case.  The
 * target is halted using the target's functions.
 *
 * @param target Pointer to the target to have the reset deasserted
 * @return ERROR_OK or an error from polling or halting the target
 */
int arm7_9_deassert_reset(struct target *target)
{
        int retval = ERROR_OK;
        LOG_DEBUG("target->state: %s", target_state_name(target));

        /* deassert reset lines */
        jtag_add_reset(0, 0);

        /* In case polling is disabled, we need to examine the
         * target and poll here for this target to work correctly.
         *
         * Otherwise, e.g. halt will fail afterwards with bogus
         * error messages as halt will believe that reset is
         * still in effect.
         */
        retval = target_examine_one(target);
        if (retval != ERROR_OK)
                return retval;

        retval = target_poll(target);
        if (retval != ERROR_OK)
                return retval;

        enum reset_types jtag_reset_config = jtag_get_reset_config();
        if (target->reset_halt && (jtag_reset_config & RESET_SRST_PULLS_TRST) != 0) {
                LOG_WARNING(
                        "srst pulls trst - can not reset into halted mode. Issuing halt after reset.");
                retval = target_halt(target);
                if (retval != ERROR_OK)
                        return retval;
        }
        return retval;
}

/**
 * Clears the halt condition for an ARM7/9 target.  If it isn't coming out of
 * reset and if DBGRQ is used, it is programmed to be deasserted.  If the reset
 * vector catch was used, it is restored.  Otherwise, the control value is
 * restored and the watchpoint unit is restored if it was in use.
 *
 * @param target Pointer to the ARM7/9 target to have halt cleared
 * @return Always ERROR_OK
 */
static int arm7_9_clear_halt(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct reg *dbg_ctrl = &arm7_9->eice_cache->reg_list[EICE_DBG_CTRL];

        /* we used DBGRQ only if we didn't come out of reset */
        if (!arm7_9->debug_entry_from_reset && arm7_9->use_dbgrq) {
                /* program EmbeddedICE Debug Control Register to deassert DBGRQ
                 */
                buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGRQ, 1, 0);
                embeddedice_store_reg(dbg_ctrl);
        } else {
                if (arm7_9->debug_entry_from_reset && arm7_9->has_vector_catch) {
                        /* if we came out of reset, and vector catch is supported, we used
                         * vector catch to enter debug state
                         * restore the register in that case
                         */
                        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_VEC_CATCH]);
                } else {
                        /* restore registers if watchpoint unit 0 was in use
                         */
                        if (arm7_9->wp0_used) {
                                if (arm7_9->debug_entry_from_reset)
                                        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[
                                                        EICE_W0_ADDR_VALUE]);
                                embeddedice_store_reg(&arm7_9->eice_cache->reg_list[
                                                EICE_W0_ADDR_MASK]);
                                embeddedice_store_reg(&arm7_9->eice_cache->reg_list[
                                                EICE_W0_DATA_MASK]);
                                embeddedice_store_reg(&arm7_9->eice_cache->reg_list[
                                                EICE_W0_CONTROL_MASK]);
                        }
                        /* control value always has to be restored, as it was either disabled,
                         * or enabled with possibly different bits
                         */
                        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE]);
                }
        }

        return ERROR_OK;
}

/**
 * Issue a software reset and halt to an ARM7/9 target.  The target is halted
 * and then there is a wait until the processor shows the halt.  This wait can
 * timeout and results in an error being returned.  The software reset involves
 * clearing the halt, updating the debug control register, changing to ARM mode,
 * reset of the program counter, and reset of all of the registers.
 *
 * @param target Pointer to the ARM7/9 target to be reset and halted by software
 * @return Error status if any of the commands fail, otherwise ERROR_OK
 */
int arm7_9_soft_reset_halt(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct reg *dbg_stat = &arm7_9->eice_cache->reg_list[EICE_DBG_STAT];
        struct reg *dbg_ctrl = &arm7_9->eice_cache->reg_list[EICE_DBG_CTRL];
        int i;
        int retval;

        /* FIX!!! replace some of this code with tcl commands
         *
         * halt # the halt command is synchronous
         * armv4_5 core_state arm
         *
         */

        retval = target_halt(target);
        if (retval != ERROR_OK)
                return retval;

        long long then = timeval_ms();
        int timeout;
        while (!(timeout = ((timeval_ms()-then) > 1000))) {
                if (buf_get_u32(dbg_stat->value, EICE_DBG_STATUS_DBGACK, 1) != 0)
                        break;
                embeddedice_read_reg(dbg_stat);
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                if (debug_level >= 3)
                        alive_sleep(100);
                else
                        keep_alive();
        }
        if (timeout) {
                LOG_ERROR("Failed to halt CPU after 1 sec");
                return ERROR_TARGET_TIMEOUT;
        }
        target->state = TARGET_HALTED;

        /* program EmbeddedICE Debug Control Register to assert DBGACK and INTDIS
         * ensure that DBGRQ is cleared
         */
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGACK, 1, 1);
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGRQ, 1, 0);
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_INTDIS, 1, 1);
        embeddedice_store_reg(dbg_ctrl);

        retval = arm7_9_clear_halt(target);
        if (retval != ERROR_OK)
                return retval;

        /* if the target is in Thumb state, change to ARM state */
        if (buf_get_u32(dbg_stat->value, EICE_DBG_STATUS_ITBIT, 1)) {
                uint32_t r0_thumb, pc_thumb;
                LOG_DEBUG("target entered debug from Thumb state, changing to ARM");
                /* Entered debug from Thumb mode */
                arm->core_state = ARM_STATE_THUMB;
                arm7_9->change_to_arm(target, &r0_thumb, &pc_thumb);
        }

        /* REVISIT likewise for bit 5 -- switch Jazelle-to-ARM */

        /* all register content is now invalid */
        register_cache_invalidate(arm->core_cache);

        /* SVC, ARM state, IRQ and FIQ disabled */
        uint32_t cpsr;

        cpsr = buf_get_u32(arm->cpsr->value, 0, 32);
        cpsr &= ~0xff;
        cpsr |= 0xd3;
        arm_set_cpsr(arm, cpsr);
        arm->cpsr->dirty = true;

        /* start fetching from 0x0 */
        buf_set_u32(arm->pc->value, 0, 32, 0x0);
        arm->pc->dirty = true;
        arm->pc->valid = true;

        /* reset registers */
        for (i = 0; i <= 14; i++) {
                struct reg *r = arm_reg_current(arm, i);

                buf_set_u32(r->value, 0, 32, 0xffffffff);
                r->dirty = true;
                r->valid = true;
        }

        retval = target_call_event_callbacks(target, TARGET_EVENT_HALTED);
        if (retval != ERROR_OK)
                return retval;

        return ERROR_OK;
}

/**
 * Halt an ARM7/9 target.  This is accomplished by either asserting the DBGRQ
 * line or by programming a watchpoint to trigger on any address.  It is
 * considered a bug to call this function while the target is in the
 * TARGET_RESET state.
 *
 * @param target Pointer to the ARM7/9 target to be halted
 * @return Always ERROR_OK
 */
int arm7_9_halt(struct target *target)
{
        if (target->state == TARGET_RESET) {
                LOG_ERROR(
                        "BUG: arm7/9 does not support halt during reset. This is handled in arm7_9_assert_reset()");
                return ERROR_OK;
        }

        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct reg *dbg_ctrl = &arm7_9->eice_cache->reg_list[EICE_DBG_CTRL];

        LOG_DEBUG("target->state: %s",
                target_state_name(target));

        if (target->state == TARGET_HALTED) {
                LOG_DEBUG("target was already halted");
                return ERROR_OK;
        }

        if (target->state == TARGET_UNKNOWN)
                LOG_WARNING("target was in unknown state when halt was requested");

        if (arm7_9->use_dbgrq) {
                /* program EmbeddedICE Debug Control Register to assert DBGRQ
                 */
                if (arm7_9->set_special_dbgrq)
                        arm7_9->set_special_dbgrq(target);
                else {
                        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGRQ, 1, 1);
                        embeddedice_store_reg(dbg_ctrl);
                }
        } else {
                /* program watchpoint unit to match on any address
                 */
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE],
                        EICE_W_CTRL_ENABLE);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK],
                        ~EICE_W_CTRL_NOPC & 0xff);
        }

        target->debug_reason = DBG_REASON_DBGRQ;

        return ERROR_OK;
}

/**
 * Handle an ARM7/9 target's entry into debug mode.  The halt is cleared on the
 * ARM.  The JTAG queue is then executed and the reason for debug entry is
 * examined.  Once done, the target is verified to be halted and the processor
 * is forced into ARM mode.  The core registers are saved for the current core
 * mode and the program counter (register 15) is updated as needed.  The core
 * registers and CPSR and SPSR are saved for restoration later.
 *
 * @param target Pointer to target that is entering debug mode
 * @return Error code if anything fails, otherwise ERROR_OK
 */
static int arm7_9_debug_entry(struct target *target)
{
        int i;
        uint32_t context[16];
        uint32_t *context_p[16];
        uint32_t r0_thumb, pc_thumb;
        uint32_t cpsr, cpsr_mask = 0;
        int retval;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct reg *dbg_stat = &arm7_9->eice_cache->reg_list[EICE_DBG_STAT];
        struct reg *dbg_ctrl = &arm7_9->eice_cache->reg_list[EICE_DBG_CTRL];

#ifdef _DEBUG_ARM7_9_
        LOG_DEBUG("-");
#endif

        /* program EmbeddedICE Debug Control Register to assert DBGACK and INTDIS
         * ensure that DBGRQ is cleared
         */
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGACK, 1, 1);
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGRQ, 1, 0);
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_INTDIS, 1, 1);
        embeddedice_store_reg(dbg_ctrl);

        retval = arm7_9_clear_halt(target);
        if (retval != ERROR_OK)
                return retval;

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

        retval = arm7_9->examine_debug_reason(target);
        if (retval != ERROR_OK)
                return retval;

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* if the target is in Thumb state, change to ARM state */
        if (buf_get_u32(dbg_stat->value, EICE_DBG_STATUS_ITBIT, 1)) {
                LOG_DEBUG("target entered debug from Thumb state");
                /* Entered debug from Thumb mode */
                arm->core_state = ARM_STATE_THUMB;
                cpsr_mask = 1 << 5;
                arm7_9->change_to_arm(target, &r0_thumb, &pc_thumb);
                LOG_DEBUG("r0_thumb: 0x%8.8" PRIx32
                        ", pc_thumb: 0x%8.8" PRIx32, r0_thumb, pc_thumb);
        } else if (buf_get_u32(dbg_stat->value, 5, 1)) {
                /* \todo Get some vaguely correct handling of Jazelle, if
                 * anyone ever uses it and full info becomes available.
                 * See ARM9EJS TRM B.7.1 for how to switch J->ARM; and
                 * B.7.3 for the reverse.  That'd be the bare minimum...
                 */
                LOG_DEBUG("target entered debug from Jazelle state");
                arm->core_state = ARM_STATE_JAZELLE;
                cpsr_mask = 1 << 24;
                LOG_ERROR("Jazelle debug entry -- BROKEN!");
        } else {
                LOG_DEBUG("target entered debug from ARM state");
                /* Entered debug from ARM mode */
                arm->core_state = ARM_STATE_ARM;
        }

        for (i = 0; i < 16; i++)
                context_p[i] = &context[i];
        /* save core registers (r0 - r15 of current core mode) */
        arm7_9->read_core_regs(target, 0xffff, context_p);

        arm7_9->read_xpsr(target, &cpsr, 0);

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

        /* Sync our CPSR copy with J or T bits EICE reported, but
         * which we then erased by putting the core into ARM mode.
         */
        arm_set_cpsr(arm, cpsr | cpsr_mask);

        if (!is_arm_mode(arm->core_mode)) {
                target->state = TARGET_UNKNOWN;
                LOG_ERROR("cpsr contains invalid mode value - communication failure");
                return ERROR_TARGET_FAILURE;
        }

        LOG_DEBUG("target entered debug state in %s mode",
                arm_mode_name(arm->core_mode));

        if (arm->core_state == ARM_STATE_THUMB) {
                LOG_DEBUG("thumb state, applying fixups");
                context[0] = r0_thumb;
                context[15] = pc_thumb;
        } else if (arm->core_state == ARM_STATE_ARM) {
                /* adjust value stored by STM */
                context[15] -= 3 * 4;
        }

        if ((target->debug_reason != DBG_REASON_DBGRQ) || (!arm7_9->use_dbgrq))
                context[15] -= 3 * ((arm->core_state == ARM_STATE_ARM) ? 4 : 2);
        else
                context[15] -= arm7_9->dbgreq_adjust_pc *
                        ((arm->core_state == ARM_STATE_ARM) ? 4 : 2);

        for (i = 0; i <= 15; i++) {
                struct reg *r = arm_reg_current(arm, i);

                LOG_DEBUG("r%i: 0x%8.8" PRIx32 "", i, context[i]);

                buf_set_u32(r->value, 0, 32, context[i]);
                /* r0 and r15 (pc) have to be restored later */
                r->dirty = (i == 0) || (i == 15);
                r->valid = true;
        }

        LOG_DEBUG("entered debug state at PC 0x%" PRIx32 "", context[15]);

        /* exceptions other than USR & SYS have a saved program status register */
        if (arm->spsr) {
                uint32_t spsr;
                arm7_9->read_xpsr(target, &spsr, 1);
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return retval;
                buf_set_u32(arm->spsr->value, 0, 32, spsr);
                arm->spsr->dirty = false;
                arm->spsr->valid = true;
        }

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

        if (arm7_9->post_debug_entry) {
                retval = arm7_9->post_debug_entry(target);
                if (retval != ERROR_OK)
                        return retval;
        }

        return ERROR_OK;
}

/**
 * Validate the full context for an ARM7/9 target in all processor modes.  If
 * there are any invalid registers for the target, they will all be read.  This
 * includes the PSR.
 *
 * @param target Pointer to the ARM7/9 target to capture the full context from
 * @return Error if the target is not halted, has an invalid core mode, or if
 *         the JTAG queue fails to execute
 */
static int arm7_9_full_context(struct target *target)
{
        int i;
        int retval;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct {
                uint32_t value;
                uint8_t *reg_p;
        } read_cache[6 * (16 + 1)];
        int read_cache_idx = 0;

        LOG_DEBUG("-");

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (!is_arm_mode(arm->core_mode)) {
                LOG_ERROR("not a valid arm core mode - communication failure?");
                return ERROR_FAIL;
        }

        /* iterate through processor modes (User, FIQ, IRQ, SVC, ABT, UND)
         * SYS shares registers with User, so we don't touch SYS
         */
        for (i = 0; i < 6; i++) {
                uint32_t mask = 0;
                uint32_t *reg_p[16];
                int j;
                bool valid = true;

                /* check if there are invalid registers in the current mode
                 */
                for (j = 0; j <= 16; j++) {
                        if (!ARMV4_5_CORE_REG_MODE(arm->core_cache, armv4_5_number_to_mode(i), j).valid)
                                valid = false;
                }

                if (!valid) {
                        uint32_t tmp_cpsr;

                        /* change processor mode (and mask T bit) */
                        tmp_cpsr = buf_get_u32(arm->cpsr->value, 0, 8)
                                & 0xe0;
                        tmp_cpsr |= armv4_5_number_to_mode(i);
                        tmp_cpsr &= ~0x20;
                        arm7_9->write_xpsr_im8(target, tmp_cpsr & 0xff, 0, 0);

                        for (j = 0; j < 15; j++) {
                                if (!ARMV4_5_CORE_REG_MODE(arm->core_cache,
                                                armv4_5_number_to_mode(i), j).valid) {
                                        read_cache[read_cache_idx].reg_p = ARMV4_5_CORE_REG_MODE(
                                                        arm->core_cache,
                                                        armv4_5_number_to_mode(i),
                                                        j).value;
                                        reg_p[j] = &read_cache[read_cache_idx].value;
                                        read_cache_idx++;
                                        mask |= 1 << j;
                                        ARMV4_5_CORE_REG_MODE(arm->core_cache,
                                                armv4_5_number_to_mode(i),
                                                j).valid = true;
                                        ARMV4_5_CORE_REG_MODE(arm->core_cache,
                                                armv4_5_number_to_mode(i),
                                                j).dirty = false;
                                }
                        }

                        /* if only the PSR is invalid, mask is all zeroes */
                        if (mask)
                                arm7_9->read_core_regs(target, mask, reg_p);

                        /* check if the PSR has to be read */
                        if (!ARMV4_5_CORE_REG_MODE(arm->core_cache, armv4_5_number_to_mode(i),
                                        16).valid) {
                                read_cache[read_cache_idx].reg_p = ARMV4_5_CORE_REG_MODE(arm->core_cache,
                                        armv4_5_number_to_mode(i), 16).value;
                                arm7_9->read_xpsr(target, &read_cache[read_cache_idx].value, 1);
                                read_cache_idx++;
                                ARMV4_5_CORE_REG_MODE(arm->core_cache, armv4_5_number_to_mode(i),
                                        16).valid = true;
                                ARMV4_5_CORE_REG_MODE(arm->core_cache, armv4_5_number_to_mode(i),
                                        16).dirty = false;
                        }
                }
        }

        /* restore processor mode (mask T bit) */
        arm7_9->write_xpsr_im8(target,
                buf_get_u32(arm->cpsr->value, 0, 8) & ~0x20, 0, 0);

        retval = jtag_execute_queue();
        if (retval != ERROR_OK)
                return retval;
        /*
         * FIXME: regs in cache should be tagged as 'valid' only now,
         * not before the jtag_execute_queue()
         */
        while (read_cache_idx) {
                read_cache_idx--;
                buf_set_u32(read_cache[read_cache_idx].reg_p, 0, 32, read_cache[read_cache_idx].value);
        }
        return ERROR_OK;
}

/**
 * Restore the processor context on an ARM7/9 target.  The full processor
 * context is analyzed to see if any of the registers are dirty on this end, but
 * have a valid new value.  If this is the case, the processor is changed to the
 * appropriate mode and the new register values are written out to the
 * processor.  If there happens to be a dirty register with an invalid value, an
 * error will be logged.
 *
 * @param target Pointer to the ARM7/9 target to have its context restored
 * @return Error status if the target is not halted or the core mode in the
 * armv4_5 struct is invalid.
 */
static int arm7_9_restore_context(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct reg *reg;
        enum arm_mode current_mode = arm->core_mode;
        int i, j;
        bool dirty;
        int mode_change;

        LOG_DEBUG("-");

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (arm7_9->pre_restore_context)
                arm7_9->pre_restore_context(target);

        if (!is_arm_mode(arm->core_mode)) {
                LOG_ERROR("not a valid arm core mode - communication failure?");
                return ERROR_FAIL;
        }

        /* iterate through processor modes (User, FIQ, IRQ, SVC, ABT, UND)
         * SYS shares registers with User, so we don't touch SYS
         */
        for (i = 0; i < 6; i++) {
                LOG_DEBUG("examining %s mode",
                        arm_mode_name(arm->core_mode));
                dirty = false;
                mode_change = 0;
                /* check if there are dirty registers in the current mode
                */
                for (j = 0; j <= 16; j++) {
                        reg = &ARMV4_5_CORE_REG_MODE(arm->core_cache, armv4_5_number_to_mode(i), j);
                        if (reg->dirty) {
                                if (reg->valid) {
                                        dirty = true;
                                        LOG_DEBUG("examining dirty reg: %s", reg->name);
                                        struct arm_reg *reg_arch_info;
                                        reg_arch_info = reg->arch_info;
                                        if ((reg_arch_info->mode != ARM_MODE_ANY)
                                                        && (reg_arch_info->mode != current_mode)
                                                        && !((reg_arch_info->mode == ARM_MODE_USR)
                                                        && (arm->core_mode == ARM_MODE_SYS))
                                                        && !((reg_arch_info->mode == ARM_MODE_SYS)
                                                        && (arm->core_mode == ARM_MODE_USR))) {
                                                mode_change = 1;
                                                LOG_DEBUG("require mode change");
                                        }
                                } else
                                        LOG_ERROR("BUG: dirty register '%s', but no valid data",
                                                reg->name);
                        }
                }

                if (dirty) {
                        uint32_t mask = 0x0;
                        int num_regs = 0;
                        uint32_t regs[16];

                        if (mode_change) {
                                uint32_t tmp_cpsr;

                                /* change processor mode (mask T bit) */
                                tmp_cpsr = buf_get_u32(arm->cpsr->value,
                                                0, 8) & 0xe0;
                                tmp_cpsr |= armv4_5_number_to_mode(i);
                                tmp_cpsr &= ~0x20;
                                arm7_9->write_xpsr_im8(target, tmp_cpsr & 0xff, 0, 0);
                                current_mode = armv4_5_number_to_mode(i);
                        }

                        for (j = 0; j <= 14; j++) {
                                reg = &ARMV4_5_CORE_REG_MODE(arm->core_cache,
                                                armv4_5_number_to_mode(i),
                                                j);

                                if (reg->dirty) {
                                        regs[j] = buf_get_u32(reg->value, 0, 32);
                                        mask |= 1 << j;
                                        num_regs++;
                                        reg->dirty = false;
                                        reg->valid = true;
                                        LOG_DEBUG("writing register %i mode %s "
                                                "with value 0x%8.8" PRIx32, j,
                                                arm_mode_name(arm->core_mode),
                                                regs[j]);
                                }
                        }

                        if (mask)
                                arm7_9->write_core_regs(target, mask, regs);

                        reg =
                                &ARMV4_5_CORE_REG_MODE(arm->core_cache, armv4_5_number_to_mode(
                                                i), 16);
                        struct arm_reg *reg_arch_info;
                        reg_arch_info = reg->arch_info;
                        if ((reg->dirty) && (reg_arch_info->mode != ARM_MODE_ANY)) {
                                LOG_DEBUG("writing SPSR of mode %i with value 0x%8.8" PRIx32 "",
                                        i,
                                        buf_get_u32(reg->value, 0, 32));
                                arm7_9->write_xpsr(target, buf_get_u32(reg->value, 0, 32), 1);
                        }
                }
        }

        if (!arm->cpsr->dirty && (arm->core_mode != current_mode)) {
                /* restore processor mode (mask T bit) */
                uint32_t tmp_cpsr;

                tmp_cpsr = buf_get_u32(arm->cpsr->value, 0, 8) & 0xE0;
                tmp_cpsr |= armv4_5_number_to_mode(i);
                tmp_cpsr &= ~0x20;
                LOG_DEBUG("writing lower 8 bit of cpsr with value 0x%2.2x", (unsigned)(tmp_cpsr));
                arm7_9->write_xpsr_im8(target, tmp_cpsr & 0xff, 0, 0);

        } else if (arm->cpsr->dirty) {
                /* CPSR has been changed, full restore necessary (mask T bit) */
                LOG_DEBUG("writing cpsr with value 0x%8.8" PRIx32,
                        buf_get_u32(arm->cpsr->value, 0, 32));
                arm7_9->write_xpsr(target,
                        buf_get_u32(arm->cpsr->value, 0, 32)
                        & ~0x20, 0);
                arm->cpsr->dirty = false;
                arm->cpsr->valid = true;
        }

        /* restore PC */
        LOG_DEBUG("writing PC with value 0x%8.8" PRIx32,
                buf_get_u32(arm->pc->value, 0, 32));
        arm7_9->write_pc(target, buf_get_u32(arm->pc->value, 0, 32));
        arm->pc->dirty = false;

        return ERROR_OK;
}

/**
 * Restart the core of an ARM7/9 target.  A RESTART command is sent to the
 * instruction register and the JTAG state is set to TAP_IDLE causing a core
 * restart.
 *
 * @param target Pointer to the ARM7/9 target to be restarted
 * @return Result of executing the JTAG queue
 */
static int arm7_9_restart_core(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        int retval;

        /* set RESTART instruction */
        if (arm7_9->need_bypass_before_restart) {
                arm7_9->need_bypass_before_restart = 0;

                retval = arm_jtag_set_instr(jtag_info->tap, 0xf, NULL, TAP_IDLE);
                if (retval != ERROR_OK)
                        return retval;
        }
        retval = arm_jtag_set_instr(jtag_info->tap, 0x4, NULL, TAP_IDLE);
        if (retval != ERROR_OK)
                return retval;

        jtag_add_runtest(1, TAP_IDLE);
        return jtag_execute_queue();
}

/**
 * Enable the watchpoints on an ARM7/9 target.  The target's watchpoints are
 * iterated through and are set on the target if they aren't already set.
 *
 * @param target Pointer to the ARM7/9 target to enable watchpoints on
 */
static void arm7_9_enable_watchpoints(struct target *target)
{
        struct watchpoint *watchpoint = target->watchpoints;

        while (watchpoint) {
                if (!watchpoint->is_set)
                        arm7_9_set_watchpoint(target, watchpoint);
                watchpoint = watchpoint->next;
        }
}

/**
 * Enable the breakpoints on an ARM7/9 target.  The target's breakpoints are
 * iterated through and are set on the target.
 *
 * @param target Pointer to the ARM7/9 target to enable breakpoints on
 */
static void arm7_9_enable_breakpoints(struct target *target)
{
        struct breakpoint *breakpoint = target->breakpoints;

        /* set any pending breakpoints */
        while (breakpoint) {
                arm7_9_set_breakpoint(target, breakpoint);
                breakpoint = breakpoint->next;
        }
}

int arm7_9_resume(struct target *target,
        int current,
        target_addr_t address,
        int handle_breakpoints,
        int debug_execution)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct reg *dbg_ctrl = &arm7_9->eice_cache->reg_list[EICE_DBG_CTRL];
        int err, retval = ERROR_OK;

        LOG_DEBUG("-");

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        if (!debug_execution)
                target_free_all_working_areas(target);

        /* current = 1: continue on current pc, otherwise continue at <address> */
        if (!current)
                buf_set_u32(arm->pc->value, 0, 32, address);

        uint32_t current_pc;
        current_pc = buf_get_u32(arm->pc->value, 0, 32);

        /* the front-end may request us not to handle breakpoints */
        if (handle_breakpoints) {
                struct breakpoint *breakpoint;
                breakpoint = breakpoint_find(target,
                                buf_get_u32(arm->pc->value, 0, 32));
                if (breakpoint) {
                        LOG_DEBUG("unset breakpoint at 0x%8.8" TARGET_PRIxADDR " (id: %" PRIu32,
                                breakpoint->address,
                                breakpoint->unique_id);
                        retval = arm7_9_unset_breakpoint(target, breakpoint);
                        if (retval != ERROR_OK)
                                return retval;

                        /* calculate PC of next instruction */
                        uint32_t next_pc;
                        retval = arm_simulate_step(target, &next_pc);
                        if (retval != ERROR_OK) {
                                uint32_t current_opcode;
                                target_read_u32(target, current_pc, &current_opcode);
                                LOG_ERROR(
                                        "Couldn't calculate PC of next instruction, current opcode was 0x%8.8" PRIx32 "",
                                        current_opcode);
                                return retval;
                        }

                        LOG_DEBUG("enable single-step");
                        arm7_9->enable_single_step(target, next_pc);

                        target->debug_reason = DBG_REASON_SINGLESTEP;

                        retval = arm7_9_restore_context(target);
                        if (retval != ERROR_OK)
                                return retval;

                        if (arm->core_state == ARM_STATE_ARM)
                                arm7_9->branch_resume(target);
                        else if (arm->core_state == ARM_STATE_THUMB)
                                arm7_9->branch_resume_thumb(target);
                        else {
                                LOG_ERROR("unhandled core state");
                                return ERROR_FAIL;
                        }

                        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGACK, 1, 0);
                        embeddedice_write_reg(dbg_ctrl,
                                buf_get_u32(dbg_ctrl->value, 0, dbg_ctrl->size));
                        err = arm7_9_execute_sys_speed(target);

                        LOG_DEBUG("disable single-step");
                        arm7_9->disable_single_step(target);

                        if (err != ERROR_OK) {
                                retval = arm7_9_set_breakpoint(target, breakpoint);
                                if (retval != ERROR_OK)
                                        return retval;
                                target->state = TARGET_UNKNOWN;
                                return err;
                        }

                        retval = arm7_9_debug_entry(target);
                        if (retval != ERROR_OK)
                                return retval;
                        LOG_DEBUG("new PC after step: 0x%8.8" PRIx32,
                                buf_get_u32(arm->pc->value, 0, 32));

                        LOG_DEBUG("set breakpoint at 0x%8.8" TARGET_PRIxADDR "", breakpoint->address);
                        retval = arm7_9_set_breakpoint(target, breakpoint);
                        if (retval != ERROR_OK)
                                return retval;
                }
        }

        /* enable any pending breakpoints and watchpoints */
        arm7_9_enable_breakpoints(target);
        arm7_9_enable_watchpoints(target);

        retval = arm7_9_restore_context(target);
        if (retval != ERROR_OK)
                return retval;

        if (arm->core_state == ARM_STATE_ARM)
                arm7_9->branch_resume(target);
        else if (arm->core_state == ARM_STATE_THUMB)
                arm7_9->branch_resume_thumb(target);
        else {
                LOG_ERROR("unhandled core state");
                return ERROR_FAIL;
        }

        /* deassert DBGACK and INTDIS */
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGACK, 1, 0);
        /* INTDIS only when we really resume, not during debug execution */
        if (!debug_execution)
                buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_INTDIS, 1, 0);
        embeddedice_write_reg(dbg_ctrl, buf_get_u32(dbg_ctrl->value, 0, dbg_ctrl->size));

        retval = arm7_9_restart_core(target);
        if (retval != ERROR_OK)
                return retval;

        target->debug_reason = DBG_REASON_NOTHALTED;

        if (!debug_execution) {
                /* registers are now invalid */
                register_cache_invalidate(arm->core_cache);
                target->state = TARGET_RUNNING;
                retval = target_call_event_callbacks(target, TARGET_EVENT_RESUMED);
                if (retval != ERROR_OK)
                        return retval;
        } else {
                target->state = TARGET_DEBUG_RUNNING;
                retval = target_call_event_callbacks(target, TARGET_EVENT_DEBUG_RESUMED);
                if (retval != ERROR_OK)
                        return retval;
        }

        LOG_DEBUG("target resumed");

        return ERROR_OK;
}

void arm7_9_enable_eice_step(struct target *target, uint32_t next_pc)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        uint32_t current_pc;
        current_pc = buf_get_u32(arm->pc->value, 0, 32);

        if (next_pc != current_pc) {
                /* setup an inverse breakpoint on the current PC
                * - comparator 1 matches the current address
                * - rangeout from comparator 1 is connected to comparator 0 rangein
                * - comparator 0 matches any address, as long as rangein is low */
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE],
                        EICE_W_CTRL_ENABLE);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK],
                        ~(EICE_W_CTRL_RANGE | EICE_W_CTRL_NOPC) & 0xff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_VALUE],
                        current_pc);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_MASK], 0);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE], 0x0);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_MASK],
                        ~EICE_W_CTRL_NOPC & 0xff);
        } else {
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE], 0x0);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK], 0xff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_VALUE], next_pc);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_MASK], 0);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_MASK], 0xffffffff);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE],
                        EICE_W_CTRL_ENABLE);
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_MASK],
                        ~EICE_W_CTRL_NOPC & 0xff);
        }
}

void arm7_9_disable_eice_step(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W0_ADDR_MASK]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W0_DATA_MASK]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_VALUE]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W0_CONTROL_MASK]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_VALUE]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W1_ADDR_MASK]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W1_DATA_MASK]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_MASK]);
        embeddedice_store_reg(&arm7_9->eice_cache->reg_list[EICE_W1_CONTROL_VALUE]);
}

int arm7_9_step(struct target *target, int current, target_addr_t address, int handle_breakpoints)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct breakpoint *breakpoint = NULL;
        int err, retval;

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* current = 1: continue on current pc, otherwise continue at <address> */
        if (!current)
                buf_set_u32(arm->pc->value, 0, 32, address);

        uint32_t current_pc = buf_get_u32(arm->pc->value, 0, 32);

        /* the front-end may request us not to handle breakpoints */
        if (handle_breakpoints)
                breakpoint = breakpoint_find(target, current_pc);
        if (breakpoint) {
                retval = arm7_9_unset_breakpoint(target, breakpoint);
                if (retval != ERROR_OK)
                        return retval;
        }

        target->debug_reason = DBG_REASON_SINGLESTEP;

        /* calculate PC of next instruction */
        uint32_t next_pc;
        retval = arm_simulate_step(target, &next_pc);
        if (retval != ERROR_OK) {
                uint32_t current_opcode;
                target_read_u32(target, current_pc, &current_opcode);
                LOG_ERROR(
                        "Couldn't calculate PC of next instruction, current opcode was 0x%8.8" PRIx32 "",
                        current_opcode);
                return retval;
        }

        retval = arm7_9_restore_context(target);
        if (retval != ERROR_OK)
                return retval;

        arm7_9->enable_single_step(target, next_pc);

        if (arm->core_state == ARM_STATE_ARM)
                arm7_9->branch_resume(target);
        else if (arm->core_state == ARM_STATE_THUMB)
                arm7_9->branch_resume_thumb(target);
        else {
                LOG_ERROR("unhandled core state");
                return ERROR_FAIL;
        }

        retval = target_call_event_callbacks(target, TARGET_EVENT_RESUMED);
        if (retval != ERROR_OK)
                return retval;

        err = arm7_9_execute_sys_speed(target);
        arm7_9->disable_single_step(target);

        /* registers are now invalid */
        register_cache_invalidate(arm->core_cache);

        if (err != ERROR_OK)
                target->state = TARGET_UNKNOWN;
        else {
                retval = arm7_9_debug_entry(target);
                if (retval != ERROR_OK)
                        return retval;
                retval = target_call_event_callbacks(target, TARGET_EVENT_HALTED);
                if (retval != ERROR_OK)
                        return retval;
                LOG_DEBUG("target stepped");
        }

        if (breakpoint) {
                retval = arm7_9_set_breakpoint(target, breakpoint);
                if (retval != ERROR_OK)
                        return retval;
        }

        return err;
}

static int arm7_9_read_core_reg(struct target *target, struct reg *r,
        int num, enum arm_mode mode)
{
        uint32_t *reg_p[16];
        int retval;
        struct arm_reg *areg = r->arch_info;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;

        if (!is_arm_mode(arm->core_mode))
                return ERROR_FAIL;
        if ((num < 0) || (num > 16))
                return ERROR_COMMAND_SYNTAX_ERROR;

        if ((mode != ARM_MODE_ANY) && (mode != arm->core_mode)
                        && (areg->mode != ARM_MODE_ANY)) {
                uint32_t tmp_cpsr;

                /* change processor mode (mask T bit) */
                tmp_cpsr = buf_get_u32(arm->cpsr->value, 0, 8) & 0xE0;
                tmp_cpsr |= mode;
                tmp_cpsr &= ~0x20;
                arm7_9->write_xpsr_im8(target, tmp_cpsr & 0xff, 0, 0);
        }

        uint32_t value = 0;
        if ((num >= 0) && (num <= 15)) {
                /* read a normal core register */
                reg_p[num] = &value;

                arm7_9->read_core_regs(target, 1 << num, reg_p);
        } else {
                /* read a program status register
                 * if the register mode is MODE_ANY, we read the cpsr, otherwise a spsr
                 */
                arm7_9->read_xpsr(target, &value, areg->mode != ARM_MODE_ANY);
        }

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

        r->valid = true;
        r->dirty = false;
        buf_set_u32(r->value, 0, 32, value);

        if ((mode != ARM_MODE_ANY) && (mode != arm->core_mode)
                        && (areg->mode != ARM_MODE_ANY)) {
                /* restore processor mode (mask T bit) */
                arm7_9->write_xpsr_im8(target,
                        buf_get_u32(arm->cpsr->value, 0, 8) & ~0x20, 0, 0);
        }

        return ERROR_OK;
}

static int arm7_9_write_core_reg(struct target *target, struct reg *r,
        int num, enum arm_mode mode, uint8_t *value)
{
        uint32_t reg[16];
        struct arm_reg *areg = r->arch_info;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;

        if (!is_arm_mode(arm->core_mode))
                return ERROR_FAIL;
        if ((num < 0) || (num > 16))
                return ERROR_COMMAND_SYNTAX_ERROR;

        if ((mode != ARM_MODE_ANY) && (mode != arm->core_mode)
                        && (areg->mode != ARM_MODE_ANY)) {
                uint32_t tmp_cpsr;

                /* change processor mode (mask T bit) */
                tmp_cpsr = buf_get_u32(arm->cpsr->value, 0, 8) & 0xE0;
                tmp_cpsr |= mode;
                tmp_cpsr &= ~0x20;
                arm7_9->write_xpsr_im8(target, tmp_cpsr & 0xff, 0, 0);
        }

        if ((num >= 0) && (num <= 15)) {
                /* write a normal core register */
                reg[num] = buf_get_u32(value, 0, 32);

                arm7_9->write_core_regs(target, 1 << num, reg);
        } else {
                /* write a program status register
                * if the register mode is MODE_ANY, we write the cpsr, otherwise a spsr
                */
                int spsr = (areg->mode != ARM_MODE_ANY);

                uint32_t t = buf_get_u32(value, 0, 32);
                /* if we're writing the CPSR, mask the T bit */
                if (!spsr)
                        t &= ~0x20;

                arm7_9->write_xpsr(target, t, spsr);
        }

        r->valid = true;
        r->dirty = false;

        if ((mode != ARM_MODE_ANY) && (mode != arm->core_mode)
                        && (areg->mode != ARM_MODE_ANY)) {
                /* restore processor mode (mask T bit) */
                arm7_9->write_xpsr_im8(target,
                                buf_get_u32(arm->cpsr->value, 0, 8) & ~0x20, 0, 0);
        }

        return jtag_execute_queue();
}

int arm7_9_read_memory(struct target *target,
        target_addr_t address,
        uint32_t size,
        uint32_t count,
        uint8_t *buffer)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        uint32_t reg[16];
        uint32_t num_accesses = 0;
        int thisrun_accesses;
        int i;
        uint32_t cpsr;
        int retval;
        int last_reg = 0;

        LOG_DEBUG("address: 0x%8.8" TARGET_PRIxADDR ", size: 0x%8.8" PRIx32 ", count: 0x%8.8" PRIx32 "",
                address, size, count);

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* sanitize arguments */
        if (((size != 4) && (size != 2) && (size != 1)) || (count == 0) || !(buffer))
                return ERROR_COMMAND_SYNTAX_ERROR;

        if (((size == 4) && (address & 0x3u)) || ((size == 2) && (address & 0x1u)))
                return ERROR_TARGET_UNALIGNED_ACCESS;

        /* load the base register with the address of the first word */
        reg[0] = address;
        arm7_9->write_core_regs(target, 0x1, reg);

        int j = 0;

        switch (size) {
                case 4:
                        while (num_accesses < count) {
                                uint32_t reg_list;
                                thisrun_accesses =
                                                ((count - num_accesses) >= 14) ? 14 : (count - num_accesses);
                                reg_list = (0xffff >> (15 - thisrun_accesses)) & 0xfffe;

                                if (last_reg <= thisrun_accesses)
                                        last_reg = thisrun_accesses;

                                arm7_9->load_word_regs(target, reg_list);

                                /* fast memory reads are only safe when the target is running
                                 * from a sufficiently high clock (32 kHz is usually too slow)
                                 */
                                if (arm7_9->fast_memory_access)
                                        retval = arm7_9_execute_fast_sys_speed(target);
                                else
                                        retval = arm7_9_execute_sys_speed(target);
                                if (retval != ERROR_OK)
                                        return retval;

                                arm7_9->read_core_regs_target_buffer(target, reg_list, buffer, 4);

                                /* advance buffer, count number of accesses */
                                buffer += thisrun_accesses * 4;
                                num_accesses += thisrun_accesses;

                                if ((j++%1024) == 0)
                                        keep_alive();
                        }
                        break;
                case 2:
                        while (num_accesses < count) {
                                uint32_t reg_list;
                                thisrun_accesses =
                                                ((count - num_accesses) >= 14) ? 14 : (count - num_accesses);
                                reg_list = (0xffff >> (15 - thisrun_accesses)) & 0xfffe;

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        if (i > last_reg)
                                            last_reg = i;
                                        arm7_9->load_hword_reg(target, i);
                                        /* fast memory reads are only safe when the target is running
                                         * from a sufficiently high clock (32 kHz is usually too slow)
                                         */
                                        if (arm7_9->fast_memory_access)
                                                retval = arm7_9_execute_fast_sys_speed(target);
                                        else
                                                retval = arm7_9_execute_sys_speed(target);
                                        if (retval != ERROR_OK)
                                                return retval;

                                }

                                arm7_9->read_core_regs_target_buffer(target, reg_list, buffer, 2);

                                /* advance buffer, count number of accesses */
                                buffer += thisrun_accesses * 2;
                                num_accesses += thisrun_accesses;

                                if ((j++%1024) == 0)
                                        keep_alive();
                        }
                        break;
                case 1:
                        while (num_accesses < count) {
                                uint32_t reg_list;
                                thisrun_accesses =
                                                ((count - num_accesses) >= 14) ? 14 : (count - num_accesses);
                                reg_list = (0xffff >> (15 - thisrun_accesses)) & 0xfffe;

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        if (i > last_reg)
                                                last_reg = i;
                                        arm7_9->load_byte_reg(target, i);
                                        /* fast memory reads are only safe when the target is running
                                         * from a sufficiently high clock (32 kHz is usually too slow)
                                         */
                                        if (arm7_9->fast_memory_access)
                                                retval = arm7_9_execute_fast_sys_speed(target);
                                        else
                                                retval = arm7_9_execute_sys_speed(target);
                                        if (retval != ERROR_OK)
                                                return retval;
                                }

                                arm7_9->read_core_regs_target_buffer(target, reg_list, buffer, 1);

                                /* advance buffer, count number of accesses */
                                buffer += thisrun_accesses * 1;
                                num_accesses += thisrun_accesses;

                                if ((j++%1024) == 0)
                                        keep_alive();
                        }
                        break;
        }

        if (!is_arm_mode(arm->core_mode))
                return ERROR_FAIL;

        for (i = 0; i <= last_reg; i++) {
                struct reg *r = arm_reg_current(arm, i);
                r->dirty = r->valid;
        }

        arm7_9->read_xpsr(target, &cpsr, 0);
        retval = jtag_execute_queue();
        if (retval != ERROR_OK) {
                LOG_ERROR("JTAG error while reading cpsr");
                return ERROR_TARGET_DATA_ABORT;
        }

        if (((cpsr & 0x1f) == ARM_MODE_ABT) && (arm->core_mode != ARM_MODE_ABT)) {
                LOG_WARNING(
                        "memory read caused data abort "
                        "(address: 0x%8.8" TARGET_PRIxADDR ", size: 0x%" PRIx32 ", count: 0x%" PRIx32 ")",
                        address,
                        size,
                        count);

                arm7_9->write_xpsr_im8(target,
                        buf_get_u32(arm->cpsr->value, 0, 8)
                        & ~0x20, 0, 0);

                return ERROR_TARGET_DATA_ABORT;
        }

        return ERROR_OK;
}

int arm7_9_write_memory(struct target *target,
        target_addr_t address,
        uint32_t size,
        uint32_t count,
        const uint8_t *buffer)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm *arm = &arm7_9->arm;
        struct reg *dbg_ctrl = &arm7_9->eice_cache->reg_list[EICE_DBG_CTRL];

        uint32_t reg[16];
        uint32_t num_accesses = 0;
        int thisrun_accesses;
        int i;
        uint32_t cpsr;
        int retval;
        int last_reg = 0;

#ifdef _DEBUG_ARM7_9_
        LOG_DEBUG("address: 0x%8.8x, size: 0x%8.8x, count: 0x%8.8x", address, size, count);
#endif

        if (target->state != TARGET_HALTED) {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        /* sanitize arguments */
        if (((size != 4) && (size != 2) && (size != 1)) || (count == 0) || !(buffer))
                return ERROR_COMMAND_SYNTAX_ERROR;

        if (((size == 4) && (address & 0x3u)) || ((size == 2) && (address & 0x1u)))
                return ERROR_TARGET_UNALIGNED_ACCESS;

        /* load the base register with the address of the first word */
        reg[0] = address;
        arm7_9->write_core_regs(target, 0x1, reg);

        /* Clear DBGACK, to make sure memory fetches work as expected */
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGACK, 1, 0);
        embeddedice_store_reg(dbg_ctrl);

        switch (size) {
                case 4:
                        while (num_accesses < count) {
                                uint32_t reg_list;
                                thisrun_accesses =
                                                ((count - num_accesses) >= 14) ? 14 : (count - num_accesses);
                                reg_list = (0xffff >> (15 - thisrun_accesses)) & 0xfffe;

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        if (i > last_reg)
                                                last_reg = i;
                                        reg[i] = target_buffer_get_u32(target, buffer);
                                        buffer += 4;
                                }

                                arm7_9->write_core_regs(target, reg_list, reg);

                                arm7_9->store_word_regs(target, reg_list);

                                /* fast memory writes are only safe when the target is running
                                 * from a sufficiently high clock (32 kHz is usually too slow)
                                 */
                                if (arm7_9->fast_memory_access)
                                        retval = arm7_9_execute_fast_sys_speed(target);
                                else {
                                        retval = arm7_9_execute_sys_speed(target);

                                        /*
                                         * if memory writes are made when the clock is running slow
                                         * (i.e. 32 kHz) which is necessary in some scripts to reconfigure
                                         * processor operations after a "reset halt" or "reset init",
                                         * need to immediately stroke the keep alive or will end up with
                                         * gdb "keep alive not sent error message" problem.
                                         */

                                        keep_alive();
                                }

                                if (retval != ERROR_OK)
                                        return retval;

                                num_accesses += thisrun_accesses;
                        }
                        break;
                case 2:
                        while (num_accesses < count) {
                                uint32_t reg_list;
                                thisrun_accesses =
                                                ((count - num_accesses) >= 14) ? 14 : (count - num_accesses);
                                reg_list = (0xffff >> (15 - thisrun_accesses)) & 0xfffe;

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        if (i > last_reg)
                                                last_reg = i;
                                        reg[i] = target_buffer_get_u16(target, buffer) & 0xffff;
                                        buffer += 2;
                                }

                                arm7_9->write_core_regs(target, reg_list, reg);

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        arm7_9->store_hword_reg(target, i);

                                        /* fast memory writes are only safe when the target is running
                                         * from a sufficiently high clock (32 kHz is usually too slow)
                                         */
                                        if (arm7_9->fast_memory_access)
                                                retval = arm7_9_execute_fast_sys_speed(target);
                                        else {
                                                retval = arm7_9_execute_sys_speed(target);

                                                /*
                                                 * if memory writes are made when the clock is running slow
                                                 * (i.e. 32 kHz) which is necessary in some scripts to reconfigure
                                                 * processor operations after a "reset halt" or "reset init",
                                                 * need to immediately stroke the keep alive or will end up with
                                                 * gdb "keep alive not sent error message" problem.
                                                 */

                                                keep_alive();
                                        }

                                        if (retval != ERROR_OK)
                                                return retval;
                                }

                                num_accesses += thisrun_accesses;
                        }
                        break;
                case 1:
                        while (num_accesses < count) {
                                uint32_t reg_list;
                                thisrun_accesses =
                                                ((count - num_accesses) >= 14) ? 14 : (count - num_accesses);
                                reg_list = (0xffff >> (15 - thisrun_accesses)) & 0xfffe;

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        if (i > last_reg)
                                                last_reg = i;
                                        reg[i] = *buffer++ & 0xff;
                                }

                                arm7_9->write_core_regs(target, reg_list, reg);

                                for (i = 1; i <= thisrun_accesses; i++) {
                                        arm7_9->store_byte_reg(target, i);
                                        /* fast memory writes are only safe when the target is running
                                         * from a sufficiently high clock (32 kHz is usually too slow)
                                         */
                                        if (arm7_9->fast_memory_access)
                                                retval = arm7_9_execute_fast_sys_speed(target);
                                        else {
                                                retval = arm7_9_execute_sys_speed(target);

                                                /*
                                                 * if memory writes are made when the clock is running slow
                                                 * (i.e. 32 kHz) which is necessary in some scripts to reconfigure
                                                 * processor operations after a "reset halt" or "reset init",
                                                 * need to immediately stroke the keep alive or will end up with
                                                 * gdb "keep alive not sent error message" problem.
                                                 */

                                                keep_alive();
                                        }

                                        if (retval != ERROR_OK)
                                                return retval;

                                }

                                num_accesses += thisrun_accesses;
                        }
                        break;
        }

        /* Re-Set DBGACK */
        buf_set_u32(dbg_ctrl->value, EICE_DBG_CONTROL_DBGACK, 1, 1);
        embeddedice_store_reg(dbg_ctrl);

        if (!is_arm_mode(arm->core_mode))
                return ERROR_FAIL;

        for (i = 0; i <= last_reg; i++) {
                struct reg *r = arm_reg_current(arm, i);
                r->dirty = r->valid;
        }

        arm7_9->read_xpsr(target, &cpsr, 0);
        retval = jtag_execute_queue();
        if (retval != ERROR_OK) {
                LOG_ERROR("JTAG error while reading cpsr");
                return ERROR_TARGET_DATA_ABORT;
        }

        if (((cpsr & 0x1f) == ARM_MODE_ABT) && (arm->core_mode != ARM_MODE_ABT)) {
                LOG_WARNING(
                        "memory write caused data abort "
                        "(address: 0x%8.8" TARGET_PRIxADDR ", size: 0x%" PRIx32 ", count: 0x%" PRIx32 ")",
                        address,
                        size,
                        count);

                arm7_9->write_xpsr_im8(target,
                        buf_get_u32(arm->cpsr->value, 0, 8)
                        & ~0x20, 0, 0);

                return ERROR_TARGET_DATA_ABORT;
        }

        return ERROR_OK;
}

int arm7_9_write_memory_opt(struct target *target,
        target_addr_t address,
        uint32_t size,
        uint32_t count,
        const uint8_t *buffer)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        int retval;

        if (size == 4 && count > 32 && arm7_9->bulk_write_memory) {
                /* Attempt to do a bulk write */
                retval = arm7_9->bulk_write_memory(target, address, count, buffer);

                if (retval == ERROR_OK)
                        return ERROR_OK;
        }

        return arm7_9->write_memory(target, address, size, count, buffer);
}

int arm7_9_write_memory_no_opt(struct target *target,
        uint32_t address,
        uint32_t size,
        uint32_t count,
        const uint8_t *buffer)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        return arm7_9->write_memory(target, address, size, count, buffer);
}

static int dcc_count;
static const uint8_t *dcc_buffer;

static int arm7_9_dcc_completion(struct target *target,
        uint32_t exit_point,
        int timeout_ms,
        void *arch_info)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        retval = target_wait_state(target, TARGET_DEBUG_RUNNING, 500);
        if (retval != ERROR_OK)
                return retval;

        int little = target->endianness == TARGET_LITTLE_ENDIAN;
        int count = dcc_count;
        const uint8_t *buffer = dcc_buffer;
        if (count > 2) {
                /* Handle first & last using standard embeddedice_write_reg and the middle ones w/the
                 * core function repeated. */
                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_COMMS_DATA],
                        fast_target_buffer_get_u32(buffer, little));
                buffer += 4;

                struct embeddedice_reg *ice_reg =
                        arm7_9->eice_cache->reg_list[EICE_COMMS_DATA].arch_info;
                uint8_t reg_addr = ice_reg->addr & 0x1f;
                struct jtag_tap *tap;
                tap = ice_reg->jtag_info->tap;

                embeddedice_write_dcc(tap, reg_addr, buffer, little, count-2);
                buffer += (count-2)*4;

                embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_COMMS_DATA],
                        fast_target_buffer_get_u32(buffer, little));
        } else {
                int i;
                for (i = 0; i < count; i++) {
                        embeddedice_write_reg(&arm7_9->eice_cache->reg_list[EICE_COMMS_DATA],
                                fast_target_buffer_get_u32(buffer, little));
                        buffer += 4;
                }
        }

        retval = target_halt(target);
        if (retval != ERROR_OK)
                return retval;
        return target_wait_state(target, TARGET_HALTED, 500);
}

static const uint32_t dcc_code[] = {
        /* r0 == input, points to memory buffer
         * r1 == scratch
         */

        /* spin until DCC control (c0) reports data arrived */
        0xee101e10,     /* w: mrc p14, #0, r1, c0, c0 */
        0xe3110001,     /*    tst r1, #1              */
        0x0afffffc,     /*    bne w                   */

        /* read word from DCC (c1), write to memory */
        0xee111e10,     /*    mrc p14, #0, r1, c1, c0 */
        0xe4801004,     /*    str r1, [r0], #4        */

        /* repeat */
        0xeafffff9      /*    b   w                   */
};

int arm7_9_bulk_write_memory(struct target *target,
        target_addr_t address,
        uint32_t count,
        const uint8_t *buffer)
{
        int retval;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (address % 4 != 0)
                return ERROR_TARGET_UNALIGNED_ACCESS;

        if (!arm7_9->dcc_downloads)
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;

        /* regrab previously allocated working_area, or allocate a new one */
        if (!arm7_9->dcc_working_area) {
                uint8_t dcc_code_buf[6 * 4];

                /* make sure we have a working area */
                if (target_alloc_working_area(target, 24, &arm7_9->dcc_working_area) != ERROR_OK) {
                        LOG_INFO("no working area available, falling back to memory writes");
                        return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
                }

                /* copy target instructions to target endianness */
                target_buffer_set_u32_array(target, dcc_code_buf, ARRAY_SIZE(dcc_code), dcc_code);

                /* write DCC code to working area, using the non-optimized
                 * memory write to avoid ending up here again */
                retval = arm7_9_write_memory_no_opt(target,
                                arm7_9->dcc_working_area->address, 4, 6, dcc_code_buf);
                if (retval != ERROR_OK)
                        return retval;
        }

        struct arm_algorithm arm_algo;
        struct reg_param reg_params[1];

        arm_algo.common_magic = ARM_COMMON_MAGIC;
        arm_algo.core_mode = ARM_MODE_SVC;
        arm_algo.core_state = ARM_STATE_ARM;

        init_reg_param(&reg_params[0], "r0", 32, PARAM_IN_OUT);

        buf_set_u32(reg_params[0].value, 0, 32, address);

        dcc_count = count;
        dcc_buffer = buffer;
        retval = armv4_5_run_algorithm_inner(target, 0, NULL, 1, reg_params,
                        arm7_9->dcc_working_area->address,
                        arm7_9->dcc_working_area->address + 6*4,
                        20*1000, &arm_algo, arm7_9_dcc_completion);

        if (retval == ERROR_OK) {
                uint32_t endaddress = buf_get_u32(reg_params[0].value, 0, 32);
                if (endaddress != (address + count*4)) {
                        LOG_ERROR(
                                "DCC write failed, expected end address 0x%08" TARGET_PRIxADDR " got 0x%0" PRIx32 "",
                                (address + count*4),
                                endaddress);
                        retval = ERROR_FAIL;
                }
        }

        destroy_reg_param(&reg_params[0]);

        return retval;
}

/**
 * Perform per-target setup that requires JTAG access.
 */
int arm7_9_examine(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        int retval;

        if (!target_was_examined(target)) {
                struct reg_cache *t, **cache_p;

                t = embeddedice_build_reg_cache(target, arm7_9);
                if (!t)
                        return ERROR_FAIL;

                cache_p = register_get_last_cache_p(&target->reg_cache);
                (*cache_p) = t;
                arm7_9->eice_cache = (*cache_p);

                if (arm7_9->arm.etm)
                        (*cache_p)->next = etm_build_reg_cache(target,
                                        &arm7_9->jtag_info,
                                        arm7_9->arm.etm);

                target_set_examined(target);
        }

        retval = embeddedice_setup(target);
        if (retval == ERROR_OK)
                retval = arm7_9_setup(target);
        if (retval == ERROR_OK && arm7_9->arm.etm)
                retval = etm_setup(target);
        return retval;
}

void arm7_9_deinit(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (target_was_examined(target))
                embeddedice_free_reg_cache(arm7_9->eice_cache);

        arm_jtag_close_connection(&arm7_9->jtag_info);
}

int arm7_9_check_reset(struct target *target)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (get_target_reset_nag() && !arm7_9->dcc_downloads)
                LOG_WARNING(
                        "NOTE! DCC downloads have not been enabled, defaulting to slow memory writes. Type 'help dcc'.");

        if (get_target_reset_nag() && (target->working_area_size == 0))
                LOG_WARNING("NOTE! Severe performance degradation without working memory enabled.");

        if (get_target_reset_nag() && !arm7_9->fast_memory_access)
                LOG_WARNING(
                        "NOTE! Severe performance degradation without fast memory access enabled. Type 'help fast'.");

        return ERROR_OK;
}

int arm7_9_endianness_callback(jtag_callback_data_t pu8_in,
                jtag_callback_data_t i_size, jtag_callback_data_t i_be,
                jtag_callback_data_t i_flip)
{
        uint8_t *in = (uint8_t *)pu8_in;
        int size = (int)i_size;
        int be = (int)i_be;
        int flip = (int)i_flip;
        uint32_t readback;

        switch (size) {
        case 4:
                readback = le_to_h_u32(in);
                if (flip)
                        readback = flip_u32(readback, 32);
                if (be)
                        h_u32_to_be(in, readback);
                else
                        h_u32_to_le(in, readback);
                break;
        case 2:
                readback = le_to_h_u16(in);
                if (flip)
                        readback = flip_u32(readback, 16);
                if (be)
                        h_u16_to_be(in, readback & 0xffff);
                else
                        h_u16_to_le(in, readback & 0xffff);
                break;
        case 1:
                readback = *in;
                if (flip)
                        readback = flip_u32(readback, 8);
                *in = readback & 0xff;
                break;
        }

        return ERROR_OK;
}

COMMAND_HANDLER(handle_arm7_9_dbgrq_command)
{
        struct target *target = get_current_target(CMD_CTX);
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (!is_arm7_9(arm7_9)) {
                command_print(CMD, "current target isn't an ARM7/ARM9 target");
                return ERROR_TARGET_INVALID;
        }

        if (CMD_ARGC > 0)
                COMMAND_PARSE_ENABLE(CMD_ARGV[0], arm7_9->use_dbgrq);

        command_print(CMD,
                "use of EmbeddedICE dbgrq instead of breakpoint for target halt %s",
                (arm7_9->use_dbgrq) ? "enabled" : "disabled");

        return ERROR_OK;
}

COMMAND_HANDLER(handle_arm7_9_fast_memory_access_command)
{
        struct target *target = get_current_target(CMD_CTX);
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (!is_arm7_9(arm7_9)) {
                command_print(CMD, "current target isn't an ARM7/ARM9 target");
                return ERROR_TARGET_INVALID;
        }

        if (CMD_ARGC > 0)
                COMMAND_PARSE_ENABLE(CMD_ARGV[0], arm7_9->fast_memory_access);

        command_print(CMD,
                "fast memory access is %s",
                (arm7_9->fast_memory_access) ? "enabled" : "disabled");

        return ERROR_OK;
}

COMMAND_HANDLER(handle_arm7_9_dcc_downloads_command)
{
        struct target *target = get_current_target(CMD_CTX);
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (!is_arm7_9(arm7_9)) {
                command_print(CMD, "current target isn't an ARM7/ARM9 target");
                return ERROR_TARGET_INVALID;
        }

        if (CMD_ARGC > 0)
                COMMAND_PARSE_ENABLE(CMD_ARGV[0], arm7_9->dcc_downloads);

        command_print(CMD,
                "dcc downloads are %s",
                (arm7_9->dcc_downloads) ? "enabled" : "disabled");

        return ERROR_OK;
}

static int arm7_9_setup_semihosting(struct target *target, int enable)
{
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);

        if (!is_arm7_9(arm7_9)) {
                LOG_USER("current target isn't an ARM7/ARM9 target");
                return ERROR_TARGET_INVALID;
        }

        if (arm7_9->has_vector_catch) {
                struct reg *vector_catch = &arm7_9->eice_cache
                        ->reg_list[EICE_VEC_CATCH];

                if (!vector_catch->valid)
                        embeddedice_read_reg(vector_catch);
                buf_set_u32(vector_catch->value, 2, 1, enable);
                embeddedice_store_reg(vector_catch);
        } else {
                /* TODO: allow optional high vectors and/or BKPT_HARD */
                if (enable)
                        breakpoint_add(target, 8, 4, BKPT_SOFT);
                else
                        breakpoint_remove(target, 8);
        }

        return ERROR_OK;
}

int arm7_9_init_arch_info(struct target *target, struct arm7_9_common *arm7_9)
{
        int retval = ERROR_OK;
        struct arm *arm = &arm7_9->arm;

        arm7_9->common_magic = ARM7_9_COMMON_MAGIC;

        retval = arm_jtag_setup_connection(&arm7_9->jtag_info);
        if (retval != ERROR_OK)
                return retval;

        /* caller must have allocated via calloc(), so everything's zeroed */

        arm7_9->wp_available_max = 2;

        arm7_9->fast_memory_access = false;
        arm7_9->dcc_downloads = false;

        arm->arch_info = arm7_9;
        arm->core_type = ARM_CORE_TYPE_STD;
        arm->read_core_reg = arm7_9_read_core_reg;
        arm->write_core_reg = arm7_9_write_core_reg;
        arm->full_context = arm7_9_full_context;
        arm->setup_semihosting = arm7_9_setup_semihosting;

        retval = arm_init_arch_info(target, arm);
        if (retval != ERROR_OK)
                return retval;

        return target_register_timer_callback(arm7_9_handle_target_request,
                1, TARGET_TIMER_TYPE_PERIODIC, target);
}

static const struct command_registration arm7_9_any_command_handlers[] = {
        {
                .name = "dbgrq",
                .handler = handle_arm7_9_dbgrq_command,
                .mode = COMMAND_ANY,
                .usage = "['enable'|'disable']",
                .help = "use EmbeddedICE dbgrq instead of breakpoint "
                        "for target halt requests",
        },
        {
                .name = "fast_memory_access",
                .handler = handle_arm7_9_fast_memory_access_command,
                .mode = COMMAND_ANY,
                .usage = "['enable'|'disable']",
                .help = "use fast memory accesses instead of slower "
                        "but potentially safer accesses",
        },
        {
                .name = "dcc_downloads",
                .handler = handle_arm7_9_dcc_downloads_command,
                .mode = COMMAND_ANY,
                .usage = "['enable'|'disable']",
                .help = "use DCC downloads for larger memory writes",
        },
        COMMAND_REGISTRATION_DONE
};
const struct command_registration arm7_9_command_handlers[] = {
        {
                .chain = arm_command_handlers,
        },
        {
                .chain = etm_command_handlers,
        },
        {
                .name = "arm7_9",
                .mode = COMMAND_ANY,
                .help = "arm7/9 specific commands",
                .usage = "",
                .chain = arm7_9_any_command_handlers,
        },
        COMMAND_REGISTRATION_DONE
};