target/arc: fix build with clang

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

/***************************************************************************
 *   Copyright (C) 2013-2015,2019-2020 Synopsys, Inc.                      *
 *   Frank Dols <frank.dols@synopsys.com>                                  *
 *   Mischa Jonker <mischa.jonker@synopsys.com>                            *
 *   Anton Kolesov <anton.kolesov@synopsys.com>                            *
 *   Evgeniy Didin <didin@synopsys.com>                                    *
 *                                                                         *
 *   SPDX-License-Identifier: GPL-2.0-or-later                             *
 ***************************************************************************/


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

#include "arc.h"



/*
 * ARC architecture specific details.
 *
 * ARC has two types of registers:
 *  1) core registers(e.g. r0,r1..) [is_core = true]
 *  2) Auxiliary registers [is_core = false]..
 *
 * Auxiliary registers at the same time can be divided into
 * read-only BCR(build configuration regs, e.g. isa_config, mpu_build) and
 * R/RW non-BCR ("control" register, e.g. pc, status32_t, debug).
 *
 * The way of accessing to Core and AUX registers differs on Jtag level.
 * BCR/non-BCR describes if the register is immutable and that reading
 * unexisting register is safe RAZ, rather then an error.
 * Note, core registers cannot be BCR.
 *
 * In arc/cpu/ tcl files all regiters are defined as core, non-BCR aux
 * and BCR aux, in "add-reg" command they are passed to three lists
 * respectively:  core_reg_descriptions, aux_reg_descriptions,
 * bcr_reg_descriptions.
 *
 * Due to the specifics of accessing to BCR/non-BCR registers there are two
 * register caches:
 *  1) core_and_aux_cache - includes registers described in
 *     core_reg_descriptions and aux_reg_descriptions lists.
 *     Used during save/restore context step.
 *  2) bcr_cache - includes registers described bcr_reg_descriptions.
 *     Currently used internally during configure step.
 */



void arc_reg_data_type_add(struct target *target,
                struct arc_reg_data_type *data_type)
{
        LOG_DEBUG("Adding %s reg_data_type", data_type->data_type.id);
        struct arc_common *arc = target_to_arc(target);
        assert(arc);

        list_add_tail(&data_type->list, &arc->reg_data_types);
}

/**
 * Private implementation of register_get_by_name() for ARC that
 * doesn't skip not [yet] existing registers. Used in many places
 * for iteration through registers and even for marking required registers as
 * existing.
 */
struct reg *arc_reg_get_by_name(struct reg_cache *first,
                const char *name, bool search_all)
{
        unsigned int i;
        struct reg_cache *cache = first;

        while (cache) {
                for (i = 0; i < cache->num_regs; i++) {
                        if (!strcmp(cache->reg_list[i].name, name))
                                return &(cache->reg_list[i]);
                }

                if (search_all)
                        cache = cache->next;
                else
                        break;
        }

        return NULL;
}


/* Initialize arc_common structure, which passes to openocd target instance */
static int arc_init_arch_info(struct target *target, struct arc_common *arc,
        struct jtag_tap *tap)
{
        arc->common_magic = ARC_COMMON_MAGIC;
        target->arch_info = arc;

        arc->jtag_info.tap = tap;

        /* The only allowed ir_length is 4 for ARC jtag. */
        if (tap->ir_length != 4) {
                LOG_ERROR("ARC jtag instruction length should be equal to 4");
                return ERROR_FAIL;
        }

        /* Add standard GDB data types */
        INIT_LIST_HEAD(&arc->reg_data_types);
        struct arc_reg_data_type *std_types = calloc(ARRAY_SIZE(standard_gdb_types),
                sizeof(*std_types));

        if (!std_types) {
                LOG_ERROR("Unable to allocate memory");
                return ERROR_FAIL;
        }

        for (unsigned int i = 0; i < ARRAY_SIZE(standard_gdb_types); i++) {
                std_types[i].data_type.type = standard_gdb_types[i].type;
                std_types[i].data_type.id = standard_gdb_types[i].id;
                arc_reg_data_type_add(target, &(std_types[i]));
        }

        /* Fields related to target descriptions */
        INIT_LIST_HEAD(&arc->core_reg_descriptions);
        INIT_LIST_HEAD(&arc->aux_reg_descriptions);
        INIT_LIST_HEAD(&arc->bcr_reg_descriptions);
        arc->num_regs = 0;
        arc->num_core_regs = 0;
        arc->num_aux_regs = 0;
        arc->num_bcr_regs = 0;
        arc->last_general_reg = ULONG_MAX;
        arc->pc_index_in_cache = ULONG_MAX;
        arc->debug_index_in_cache = ULONG_MAX;

        return ERROR_OK;
}

int arc_reg_add(struct target *target, struct arc_reg_desc *arc_reg,
                const char * const type_name, const size_t type_name_len)
{
        assert(target);
        assert(arc_reg);

        struct arc_common *arc = target_to_arc(target);
        assert(arc);

        /* Find register type */
        {
                struct arc_reg_data_type *type;
                list_for_each_entry(type, &arc->reg_data_types, list)
                        if (!strncmp(type->data_type.id, type_name, type_name_len)) {
                                arc_reg->data_type = &(type->data_type);
                                break;
                        }

                if (!arc_reg->data_type)
                        return ERROR_ARC_REGTYPE_NOT_FOUND;
        }

        if (arc_reg->is_core) {
                list_add_tail(&arc_reg->list, &arc->core_reg_descriptions);
                arc->num_core_regs += 1;
        } else if (arc_reg->is_bcr) {
                list_add_tail(&arc_reg->list, &arc->bcr_reg_descriptions);
                arc->num_bcr_regs += 1;
        } else {
                list_add_tail(&arc_reg->list, &arc->aux_reg_descriptions);
                arc->num_aux_regs += 1;
        }
        arc->num_regs += 1;

        LOG_DEBUG(
                        "added register {name=%s, num=0x%x, type=%s%s%s%s}",
                        arc_reg->name, arc_reg->arch_num, arc_reg->data_type->id,
                        arc_reg->is_core ? ", core" : "",  arc_reg->is_bcr ? ", bcr" : "",
                        arc_reg->is_general ? ", general" : ""
                );

        return ERROR_OK;
}

/* Reading core or aux register */
static int arc_get_register(struct reg *reg)
{
        assert(reg);

        struct arc_reg_desc *desc = reg->arch_info;
        struct target *target = desc->target;
        struct arc_common *arc = target_to_arc(target);

        uint32_t value;

        if (reg->valid) {
                LOG_DEBUG("Get register (cached) gdb_num=%" PRIu32 ", name=%s, value=0x%" PRIx32,
                                reg->number, desc->name, target_buffer_get_u32(target, reg->value));
                return ERROR_OK;
        }

        if (desc->is_core) {
                /* Accessing to R61/R62 registers causes Jtag hang */
                if (desc->arch_num == CORE_R61_NUM || desc->arch_num == CORE_R62_NUM) {
                        LOG_ERROR("It is forbidden to read core registers 61 and 62.");
                        return ERROR_FAIL;
                }
                CHECK_RETVAL(arc_jtag_read_core_reg_one(&arc->jtag_info, desc->arch_num,
                                        &value));
        } else {
                CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, desc->arch_num,
                        &value));
        }

        target_buffer_set_u32(target, reg->value, value);

        /* If target is unhalted all register reads should be uncached. */
        if (target->state == TARGET_HALTED)
                reg->valid = true;
        else
                reg->valid = false;

        reg->dirty = false;

        LOG_DEBUG("Get register gdb_num=%" PRIu32 ", name=%s, value=0x%" PRIx32,
                        reg->number , desc->name, value);


        return ERROR_OK;
}

/* Writing core or aux register */
static int arc_set_register(struct reg *reg, uint8_t *buf)
{
        struct arc_reg_desc *desc = reg->arch_info;
        struct target *target = desc->target;
        uint32_t value = target_buffer_get_u32(target, buf);
        /* Unlike "get" function "set" is supported only if target
        * is in halt mode. Async writes are not supported yet. */
        if (target->state != TARGET_HALTED)
                return ERROR_TARGET_NOT_HALTED;

        /* Accessing to R61/R62 registers causes Jtag hang */
        if (desc->is_core && (desc->arch_num == CORE_R61_NUM ||
                        desc->arch_num == CORE_R62_NUM)) {
                LOG_ERROR("It is forbidden to write core registers 61 and 62.");
                return ERROR_FAIL;
        }
        target_buffer_set_u32(target, reg->value, value);

        LOG_DEBUG("Set register gdb_num=%" PRIu32 ", name=%s, value=0x%08" PRIx32,
                        reg->number, desc->name, value);

        reg->valid = true;
        reg->dirty = true;

        return ERROR_OK;
}

const struct reg_arch_type arc_reg_type = {
        .get = arc_get_register,
        .set = arc_set_register,
};

/* GDB register groups. For now we suport only general and "empty" */
static const char * const reg_group_general = "general";
static const char * const reg_group_other = "";

/* Common code to initialize `struct reg` for different registers: core, aux, bcr. */
static int arc_init_reg(struct target *target, struct reg *reg,
                        struct arc_reg_desc *reg_desc, unsigned long number)
{
        assert(target);
        assert(reg);
        assert(reg_desc);

        struct arc_common *arc = target_to_arc(target);

        /* Initialize struct reg */
        reg->name = reg_desc->name;
        reg->size = 32; /* All register in ARC are 32-bit */
        reg->value = &reg_desc->reg_value;
        reg->type = &arc_reg_type;
        reg->arch_info = reg_desc;
        reg->caller_save = true; /* @todo should be configurable. */
        reg->reg_data_type = reg_desc->data_type;
        reg->feature = &reg_desc->feature;

        reg->feature->name = reg_desc->gdb_xml_feature;

        /* reg->number is used by OpenOCD as value for @regnum. Thus when setting
         * value of a register GDB will use it as a number of register in
         * P-packet. OpenOCD gdbserver will then use number of register in
         * P-packet as an array index in the reg_list returned by
         * arc_regs_get_gdb_reg_list. So to ensure that registers are assigned
         * correctly it would be required to either sort registers in
         * arc_regs_get_gdb_reg_list or to assign numbers sequentially here and
         * according to how registers will be sorted in
         * arc_regs_get_gdb_reg_list. Second options is much more simpler. */
        reg->number = number;

        if (reg_desc->is_general) {
                arc->last_general_reg = reg->number;
                reg->group = reg_group_general;
        } else {
                reg->group = reg_group_other;
        }

        return ERROR_OK;
}

/* Building aux/core reg_cache */
static int arc_build_reg_cache(struct target *target)
{
        unsigned long i = 0;
        struct arc_reg_desc *reg_desc;
        /* get pointers to arch-specific information */
        struct arc_common *arc = target_to_arc(target);
        const unsigned long num_regs = arc->num_core_regs + arc->num_aux_regs;
        struct reg_cache **cache_p = register_get_last_cache_p(&target->reg_cache);
        struct reg_cache *cache = calloc(1, sizeof(*cache));
        struct reg *reg_list = calloc(num_regs, sizeof(*reg_list));

        if (!cache || !reg_list)  {
                LOG_ERROR("Not enough memory");
                goto fail;
        }

        /* Build the process context cache */
        cache->name = "arc registers";
        cache->next = NULL;
        cache->reg_list = reg_list;
        cache->num_regs = num_regs;
        arc->core_and_aux_cache = cache;
        (*cache_p) = cache;

        if (list_empty(&arc->core_reg_descriptions)) {
                LOG_ERROR("No core registers were defined");
                goto fail;
        }

        list_for_each_entry(reg_desc, &arc->core_reg_descriptions, list) {
                CHECK_RETVAL(arc_init_reg(target, &reg_list[i], reg_desc, i));

                LOG_DEBUG("reg n=%3li name=%3s group=%s feature=%s", i,
                        reg_list[i].name, reg_list[i].group,
                        reg_list[i].feature->name);

                i += 1;
        }

        if (list_empty(&arc->aux_reg_descriptions)) {
                LOG_ERROR("No aux registers were defined");
                goto fail;
        }

        list_for_each_entry(reg_desc, &arc->aux_reg_descriptions, list) {
                 CHECK_RETVAL(arc_init_reg(target, &reg_list[i],  reg_desc, i));

                LOG_DEBUG("reg n=%3li name=%3s group=%s feature=%s", i,
                        reg_list[i].name, reg_list[i].group,
                        reg_list[i].feature->name);

                /* PC and DEBUG are essential so we search for them. */
                if (!strcmp("pc", reg_desc->name)) {
                        if (arc->pc_index_in_cache != ULONG_MAX) {
                                LOG_ERROR("Double definition of PC in configuration");
                                goto fail;
                        }
                        arc->pc_index_in_cache = i;
                } else if (!strcmp("debug", reg_desc->name)) {
                        if (arc->debug_index_in_cache != ULONG_MAX) {
                                LOG_ERROR("Double definition of DEBUG in configuration");
                                goto fail;
                        }
                        arc->debug_index_in_cache = i;
                }
                i += 1;
        }

        if (arc->pc_index_in_cache == ULONG_MAX
                        || arc->debug_index_in_cache == ULONG_MAX) {
                LOG_ERROR("`pc' and `debug' registers must be present in target description.");
                goto fail;
        }

        assert(i == (arc->num_core_regs + arc->num_aux_regs));

        arc->core_aux_cache_built = true;

        return ERROR_OK;

fail:
        free(cache);
        free(reg_list);

        return ERROR_FAIL;
}

/* Build bcr reg_cache.
 * This function must be called only after arc_build_reg_cache */
static int arc_build_bcr_reg_cache(struct target *target)
{
        /* get pointers to arch-specific information */
        struct arc_common *arc = target_to_arc(target);
        const unsigned long num_regs = arc->num_bcr_regs;
        struct reg_cache **cache_p = register_get_last_cache_p(&target->reg_cache);
        struct reg_cache *cache = malloc(sizeof(*cache));
        struct reg *reg_list = calloc(num_regs, sizeof(*reg_list));

        struct arc_reg_desc *reg_desc;
        unsigned long i = 0;
        unsigned long gdb_regnum = arc->core_and_aux_cache->num_regs;

        if (!cache || !reg_list)  {
                LOG_ERROR("Unable to allocate memory");
                goto fail;
        }

        /* Build the process context cache */
        cache->name = "arc.bcr";
        cache->next = NULL;
        cache->reg_list = reg_list;
        cache->num_regs = num_regs;
        arc->bcr_cache = cache;
        (*cache_p) = cache;

        if (list_empty(&arc->bcr_reg_descriptions)) {
                LOG_ERROR("No BCR registers are defined");
                goto fail;
        }

        list_for_each_entry(reg_desc, &arc->bcr_reg_descriptions, list) {
                 CHECK_RETVAL(arc_init_reg(target, &reg_list[i], reg_desc, gdb_regnum));
                /* BCRs always semantically, they are just read-as-zero, if there is
                 * not real register. */
                reg_list[i].exist = true;

                LOG_DEBUG("reg n=%3li name=%3s group=%s feature=%s", i,
                        reg_list[i].name, reg_list[i].group,
                        reg_list[i].feature->name);
                i += 1;
                gdb_regnum += 1;
        }

        assert(i == arc->num_bcr_regs);

        arc->bcr_cache_built = true;


        return ERROR_OK;
fail:
        free(cache);
        free(reg_list);

        return ERROR_FAIL;
}


static int arc_get_gdb_reg_list(struct target *target, struct reg **reg_list[],
        int *reg_list_size, enum target_register_class reg_class)
{
        assert(target->reg_cache);
        struct arc_common *arc = target_to_arc(target);

        /* get pointers to arch-specific information storage */
        *reg_list_size = arc->num_regs;
        *reg_list = calloc(*reg_list_size, sizeof(struct reg *));

        if (!*reg_list) {
                LOG_ERROR("Unable to allocate memory");
                return ERROR_FAIL;
        }

        /* OpenOCD gdb_server API seems to be inconsistent here: when it generates
         * XML tdesc it filters out !exist registers, however when creating a
         * g-packet it doesn't do so. REG_CLASS_ALL is used in first case, and
         * REG_CLASS_GENERAL used in the latter one. Due to this we had to filter
         * out !exist register for "general", but not for "all". Attempts to filter out
         * !exist for "all" as well will cause a failed check in OpenOCD GDB
         * server. */
        if (reg_class == REG_CLASS_ALL) {
                unsigned long i = 0;
                struct reg_cache *reg_cache = target->reg_cache;
                while (reg_cache) {
                        for (unsigned j = 0; j < reg_cache->num_regs; j++, i++)
                                (*reg_list)[i] =  &reg_cache->reg_list[j];
                        reg_cache = reg_cache->next;
                }
                assert(i == arc->num_regs);
                LOG_DEBUG("REG_CLASS_ALL: number of regs=%i", *reg_list_size);
        } else {
                unsigned long i = 0;
                unsigned long gdb_reg_number = 0;
                struct reg_cache *reg_cache = target->reg_cache;
                while (reg_cache) {
                        for (unsigned j = 0;
                                 j < reg_cache->num_regs && gdb_reg_number <= arc->last_general_reg;
                                 j++) {
                                if (reg_cache->reg_list[j].exist) {
                                        (*reg_list)[i] =  &reg_cache->reg_list[j];
                                        i++;
                                }
                                gdb_reg_number += 1;
                        }
                        reg_cache = reg_cache->next;
                }
                *reg_list_size = i;
                LOG_DEBUG("REG_CLASS_GENERAL: number of regs=%i", *reg_list_size);
        }

        return ERROR_OK;
}

/* Reading field of struct_type register */
int arc_reg_get_field(struct target *target, const char *reg_name,
                const char *field_name, uint32_t *value_ptr)
{
        struct reg_data_type_struct_field *field;

        LOG_DEBUG("getting register field (reg_name=%s, field_name=%s)", reg_name, field_name);

        /* Get register */
        struct reg *reg = arc_reg_get_by_name(target->reg_cache, reg_name, true);

        if (!reg) {
                LOG_ERROR("Requested register `%s' doens't exist.", reg_name);
                return ERROR_ARC_REGISTER_NOT_FOUND;
        }

        if (reg->reg_data_type->type != REG_TYPE_ARCH_DEFINED
            || reg->reg_data_type->type_class != REG_TYPE_CLASS_STRUCT)
                return ERROR_ARC_REGISTER_IS_NOT_STRUCT;

        /* Get field in a register */
        struct reg_data_type_struct *reg_struct =
                reg->reg_data_type->reg_type_struct;
        for (field = reg_struct->fields;
             field;
             field = field->next) {
                if (!strcmp(field->name, field_name))
                        break;
        }

        if (!field)
                return ERROR_ARC_REGISTER_FIELD_NOT_FOUND;

        if (!field->use_bitfields)
                return ERROR_ARC_FIELD_IS_NOT_BITFIELD;

        if (!reg->valid)
                CHECK_RETVAL(reg->type->get(reg));

        /* First do endiannes-safe read of register value
         * then convert it to binary buffer for further
         * field extraction */

        *value_ptr = buf_get_u32(reg->value, field->bitfield->start,
                field->bitfield->end - field->bitfield->start + 1);

        return ERROR_OK;
}

static int arc_get_register_value(struct target *target, const char *reg_name,
                uint32_t *value_ptr)
{
        LOG_DEBUG("reg_name=%s", reg_name);

        struct reg *reg = arc_reg_get_by_name(target->reg_cache, reg_name, true);

        if (!reg)
                return ERROR_ARC_REGISTER_NOT_FOUND;

        if (!reg->valid)
                CHECK_RETVAL(reg->type->get(reg));

        *value_ptr = target_buffer_get_u32(target, reg->value);

        return ERROR_OK;
}


/* Configure DCCM's */
static int arc_configure_dccm(struct target  *target)
{
        struct arc_common *arc = target_to_arc(target);

        uint32_t dccm_build_version, dccm_build_size0, dccm_build_size1;
        CHECK_RETVAL(arc_reg_get_field(target, "dccm_build", "version",
                &dccm_build_version));
        CHECK_RETVAL(arc_reg_get_field(target, "dccm_build", "size0",
                &dccm_build_size0));
        CHECK_RETVAL(arc_reg_get_field(target, "dccm_build", "size1",
                &dccm_build_size1));
        /* There is no yet support of configurable number of cycles,
         * So there is no difference between v3 and v4 */
        if ((dccm_build_version == 3 || dccm_build_version == 4) && dccm_build_size0 > 0) {
                CHECK_RETVAL(arc_get_register_value(target, "aux_dccm", &(arc->dccm_start)));
                uint32_t dccm_size = 0x100;
                dccm_size <<= dccm_build_size0;
                if (dccm_build_size0 == 0xF)
                        dccm_size <<= dccm_build_size1;
                arc->dccm_end = arc->dccm_start + dccm_size;
                LOG_DEBUG("DCCM detected start=0x%" PRIx32 " end=0x%" PRIx32,
                                arc->dccm_start, arc->dccm_end);

        }
        return ERROR_OK;
}


/* Configure ICCM's */

static int arc_configure_iccm(struct target  *target)
{
        struct arc_common *arc = target_to_arc(target);

        /* ICCM0 */
        uint32_t iccm_build_version, iccm_build_size00, iccm_build_size01;
        uint32_t aux_iccm = 0;
        CHECK_RETVAL(arc_reg_get_field(target, "iccm_build", "version",
                &iccm_build_version));
        CHECK_RETVAL(arc_reg_get_field(target, "iccm_build", "iccm0_size0",
                &iccm_build_size00));
        CHECK_RETVAL(arc_reg_get_field(target, "iccm_build", "iccm0_size1",
                &iccm_build_size01));
        if (iccm_build_version == 4 && iccm_build_size00 > 0) {
                CHECK_RETVAL(arc_get_register_value(target, "aux_iccm", &aux_iccm));
                uint32_t iccm0_size = 0x100;
                iccm0_size <<= iccm_build_size00;
                if (iccm_build_size00 == 0xF)
                        iccm0_size <<= iccm_build_size01;
                /* iccm0 start is located in highest 4 bits of aux_iccm */
                arc->iccm0_start = aux_iccm & 0xF0000000;
                arc->iccm0_end = arc->iccm0_start + iccm0_size;
                LOG_DEBUG("ICCM0 detected start=0x%" PRIx32 " end=0x%" PRIx32,
                                arc->iccm0_start, arc->iccm0_end);
        }

        /* ICCM1 */
        uint32_t iccm_build_size10, iccm_build_size11;
        CHECK_RETVAL(arc_reg_get_field(target, "iccm_build", "iccm1_size0",
                &iccm_build_size10));
        CHECK_RETVAL(arc_reg_get_field(target, "iccm_build", "iccm1_size1",
                &iccm_build_size11));
        if (iccm_build_version == 4 && iccm_build_size10 > 0) {
                /* Use value read for ICCM0 */
                if (!aux_iccm)
                        CHECK_RETVAL(arc_get_register_value(target, "aux_iccm", &aux_iccm));
                uint32_t iccm1_size = 0x100;
                iccm1_size <<= iccm_build_size10;
                if (iccm_build_size10 == 0xF)
                        iccm1_size <<= iccm_build_size11;
                arc->iccm1_start = aux_iccm & 0x0F000000;
                arc->iccm1_end = arc->iccm1_start + iccm1_size;
                LOG_DEBUG("ICCM1 detected start=0x%" PRIx32 " end=0x%" PRIx32,
                                arc->iccm1_start, arc->iccm1_end);
        }
        return ERROR_OK;
}

/* Configure some core features, depending on BCRs. */
static int arc_configure(struct target *target)
{
        LOG_DEBUG("Configuring ARC ICCM and DCCM");

        /* Configuring DCCM if DCCM_BUILD and AUX_DCCM are known registers. */
        if (arc_reg_get_by_name(target->reg_cache, "dccm_build", true) &&
            arc_reg_get_by_name(target->reg_cache, "aux_dccm", true))
                                CHECK_RETVAL(arc_configure_dccm(target));

        /* Configuring ICCM if ICCM_BUILD and AUX_ICCM are known registers. */
        if (arc_reg_get_by_name(target->reg_cache, "iccm_build", true) &&
            arc_reg_get_by_name(target->reg_cache, "aux_iccm", true))
                                CHECK_RETVAL(arc_configure_iccm(target));

        return ERROR_OK;
}

/* arc_examine is function, which is used for all arc targets*/
static int arc_examine(struct target *target)
{
        uint32_t status;
        struct arc_common *arc = target_to_arc(target);

        CHECK_RETVAL(arc_jtag_startup(&arc->jtag_info));

        if (!target_was_examined(target)) {
                CHECK_RETVAL(arc_jtag_status(&arc->jtag_info, &status));
                if (status & ARC_JTAG_STAT_RU)
                        target->state = TARGET_RUNNING;
                else
                        target->state = TARGET_HALTED;

                /* Read BCRs and configure optional registers. */
                CHECK_RETVAL(arc_configure(target));

                target_set_examined(target);
        }

        return ERROR_OK;
}

static int arc_halt(struct target *target)
{
        uint32_t value, irq_state;
        struct arc_common *arc = target_to_arc(target);

        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 (target->state == TARGET_RESET) {
                if ((jtag_get_reset_config() & RESET_SRST_PULLS_TRST) && jtag_get_srst()) {
                        LOG_ERROR("can't request a halt while in reset if nSRST pulls nTRST");
                        return ERROR_TARGET_FAILURE;
                } else {
                        target->debug_reason = DBG_REASON_DBGRQ;
                }
        }

        /* Break (stop) processor.
         * Do read-modify-write sequence, or DEBUG.UB will be reset unintentionally.
         * We do not use here arc_get/set_core_reg functions here because they imply
         * that the processor is already halted. */
        CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, AUX_DEBUG_REG, &value));
        value |= SET_CORE_FORCE_HALT; /* set the HALT bit */
        CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_DEBUG_REG, value));
        alive_sleep(1);

        /* Save current IRQ state */
        CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG, &irq_state));

        if (irq_state & AUX_STATUS32_REG_IE_BIT)
                arc->irq_state = 1;
        else
                arc->irq_state = 0;

        /* update state and notify gdb*/
        target->state = TARGET_HALTED;
        CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_HALTED));

        /* some more debug information */
        if (debug_level >= LOG_LVL_DEBUG) {
                LOG_DEBUG("core stopped (halted) DEGUB-REG: 0x%08" PRIx32, value);
                CHECK_RETVAL(arc_get_register_value(target, "status32", &value));
                LOG_DEBUG("core STATUS32: 0x%08" PRIx32, value);
        }

        return ERROR_OK;
}

/**
 * Read registers that are used in GDB g-packet. We don't read them one-by-one,
 * but do that in one batch operation to improve speed. Calls to JTAG layer are
 * expensive so it is better to make one big call that reads all necessary
 * registers, instead of many calls, one for one register.
 */
static int arc_save_context(struct target *target)
{
        int retval = ERROR_OK;
        unsigned int i;
        struct arc_common *arc = target_to_arc(target);
        struct reg *reg_list = arc->core_and_aux_cache->reg_list;

        LOG_DEBUG("Saving aux and core registers values");
        assert(reg_list);

        /* It is assumed that there is at least one AUX register in the list, for
         * example PC. */
        const uint32_t core_regs_size = arc->num_core_regs * sizeof(uint32_t);
        /* last_general_reg is inclusive number. To get count of registers it is
         * required to do +1. */
        const uint32_t regs_to_scan =
                MIN(arc->last_general_reg + 1, arc->num_regs);
        const uint32_t aux_regs_size = arc->num_aux_regs * sizeof(uint32_t);
        uint32_t *core_values = malloc(core_regs_size);
        uint32_t *aux_values = malloc(aux_regs_size);
        uint32_t *core_addrs = malloc(core_regs_size);
        uint32_t *aux_addrs = malloc(aux_regs_size);
        unsigned int core_cnt = 0;
        unsigned int aux_cnt = 0;

        if (!core_values || !core_addrs || !aux_values || !aux_addrs)  {
                LOG_ERROR("Unable to allocate memory");
                retval = ERROR_FAIL;
                goto exit;
        }

        memset(core_values, 0xff, core_regs_size);
        memset(core_addrs, 0xff, core_regs_size);
        memset(aux_values, 0xff, aux_regs_size);
        memset(aux_addrs, 0xff, aux_regs_size);

        for (i = 0; i < MIN(arc->num_core_regs, regs_to_scan); i++) {
                struct reg *reg = &(reg_list[i]);
                struct arc_reg_desc *arc_reg = reg->arch_info;
                if (!reg->valid && reg->exist) {
                        core_addrs[core_cnt] = arc_reg->arch_num;
                        core_cnt += 1;
                }
        }

        for (i = arc->num_core_regs; i < regs_to_scan; i++) {
                struct reg *reg = &(reg_list[i]);
                struct arc_reg_desc *arc_reg = reg->arch_info;
                if (!reg->valid && reg->exist) {
                        aux_addrs[aux_cnt] = arc_reg->arch_num;
                        aux_cnt += 1;
                }
        }

        /* Read data from target. */
        if (core_cnt > 0) {
                retval = arc_jtag_read_core_reg(&arc->jtag_info, core_addrs, core_cnt, core_values);
                if (ERROR_OK != retval) {
                        LOG_ERROR("Attempt to read core registers failed.");
                        retval = ERROR_FAIL;
                        goto exit;
                }
        }
        if (aux_cnt > 0) {
                retval = arc_jtag_read_aux_reg(&arc->jtag_info, aux_addrs, aux_cnt, aux_values);
                if (ERROR_OK != retval) {
                        LOG_ERROR("Attempt to read aux registers failed.");
                        retval = ERROR_FAIL;
                        goto exit;
                }
        }

        /* Parse core regs */
        core_cnt = 0;
        for (i = 0; i < MIN(arc->num_core_regs, regs_to_scan); i++) {
                struct reg *reg = &(reg_list[i]);
                struct arc_reg_desc *arc_reg = reg->arch_info;
                if (!reg->valid && reg->exist) {
                        target_buffer_set_u32(target, reg->value, core_values[core_cnt]);
                        core_cnt += 1;
                        reg->valid = true;
                        reg->dirty = false;
                        LOG_DEBUG("Get core register regnum=%" PRIu32 ", name=%s, value=0x%08" PRIx32,
                                i, arc_reg->name, core_values[core_cnt]);
                }
        }

        /* Parse aux regs */
        aux_cnt = 0;
        for (i = arc->num_core_regs; i < regs_to_scan; i++) {
                struct reg *reg = &(reg_list[i]);
                struct arc_reg_desc *arc_reg = reg->arch_info;
                if (!reg->valid && reg->exist) {
                        target_buffer_set_u32(target, reg->value, aux_values[aux_cnt]);
                        aux_cnt += 1;
                        reg->valid = true;
                        reg->dirty = false;
                        LOG_DEBUG("Get aux register regnum=%" PRIu32 ", name=%s, value=0x%08" PRIx32,
                                i , arc_reg->name, aux_values[aux_cnt]);
                }
        }

exit:
        free(core_values);
        free(core_addrs);
        free(aux_values);
        free(aux_addrs);

        return retval;
}

static int arc_examine_debug_reason(struct target *target)
{
        uint32_t debug_bh;

        /* Only check for reason if don't know it already. */
        /* BTW After singlestep at this point core is not marked as halted, so
         * reading from memory to get current instruction wouldn't work anyway.  */
        if (target->debug_reason == DBG_REASON_DBGRQ ||
            target->debug_reason == DBG_REASON_SINGLESTEP) {
                return ERROR_OK;
        }

        CHECK_RETVAL(arc_reg_get_field(target, "debug", "bh",
                                &debug_bh));

        if (debug_bh) {
                /* DEBUG.BH is set if core halted due to BRK instruction.  */
                target->debug_reason = DBG_REASON_BREAKPOINT;
        } else {
                /* TODO: Add Actionpoint check when AP support will be introduced*/
                LOG_WARNING("Unknown debug reason");
        }

        return ERROR_OK;
}

static int arc_debug_entry(struct target *target)
{
        CHECK_RETVAL(arc_save_context(target));

        /* TODO: reset internal indicators of caches states, otherwise D$/I$
         * will not be flushed/invalidated when required. */
        CHECK_RETVAL(arc_examine_debug_reason(target));

        return ERROR_OK;
}

static int arc_poll(struct target *target)
{
        uint32_t status, value;
        struct arc_common *arc = target_to_arc(target);

        /* gdb calls continuously through this arc_poll() function  */
        CHECK_RETVAL(arc_jtag_status(&arc->jtag_info, &status));

        /* check for processor halted */
        if (status & ARC_JTAG_STAT_RU) {
                if (target->state != TARGET_RUNNING) {
                        LOG_WARNING("target is still running!");
                        target->state = TARGET_RUNNING;
                }
                return ERROR_OK;
        }
        /* In some cases JTAG status register indicates that
         *  processor is in halt mode, but processor is still running.
         *  We check halt bit of AUX STATUS32 register for setting correct state. */
        if ((target->state == TARGET_RUNNING) || (target->state == TARGET_RESET)) {
                CHECK_RETVAL(arc_get_register_value(target, "status32", &value));
                if (value & AUX_STATUS32_REG_HALT_BIT) {
                        LOG_DEBUG("ARC core in halt or reset state.");
                        /* Save context if target was not in reset state */
                        if (target->state == TARGET_RUNNING)
                                CHECK_RETVAL(arc_debug_entry(target));
                        target->state = TARGET_HALTED;
                        CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_HALTED));
                } else {
                LOG_DEBUG("Discrepancy of STATUS32[0] HALT bit and ARC_JTAG_STAT_RU, "
                                                "target is still running");
                }

        } else if (target->state == TARGET_DEBUG_RUNNING) {

                target->state = TARGET_HALTED;
                LOG_DEBUG("ARC core is in debug running mode");

                CHECK_RETVAL(arc_debug_entry(target));

                CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_DEBUG_HALTED));
        }

        return ERROR_OK;
}

static int arc_assert_reset(struct target *target)
{
        struct arc_common *arc = target_to_arc(target);
        enum reset_types jtag_reset_config = jtag_get_reset_config();
        bool srst_asserted = false;

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

        if (target_has_event_action(target, TARGET_EVENT_RESET_ASSERT)) {
                /* allow scripts to override the reset event */

                target_handle_event(target, TARGET_EVENT_RESET_ASSERT);
                register_cache_invalidate(arc->core_and_aux_cache);
                 /* An ARC target might be in halt state after reset, so
                 * if script requested processor to resume, then it must
                 * be manually started to ensure that this request
                 * is satisfied. */
                if (target->state == TARGET_HALTED && !target->reset_halt) {
                        /* Resume the target and continue from the current
                         * PC register value. */
                        LOG_DEBUG("Starting CPU execution after reset");
                        CHECK_RETVAL(target_resume(target, 1, 0, 0, 0));
                }
                target->state = TARGET_RESET;

                return ERROR_OK;
        }

        /* some cores support connecting while srst is asserted
         * use that mode if it has been configured */
        if (!(jtag_reset_config & RESET_SRST_PULLS_TRST) &&
                        (jtag_reset_config & RESET_SRST_NO_GATING)) {
                jtag_add_reset(0, 1);
                srst_asserted = true;
        }

        if (jtag_reset_config & RESET_HAS_SRST) {
                /* should issue a srst only, but we may have to assert trst as well */
                if (jtag_reset_config & RESET_SRST_PULLS_TRST)
                        jtag_add_reset(1, 1);
                else if (!srst_asserted)
                        jtag_add_reset(0, 1);
        }

        target->state = TARGET_RESET;
        jtag_add_sleep(50000);

        register_cache_invalidate(arc->core_and_aux_cache);

        if (target->reset_halt)
                CHECK_RETVAL(target_halt(target));

        return ERROR_OK;
}

static int arc_deassert_reset(struct target *target)
{
        LOG_DEBUG("target->state: %s", target_state_name(target));

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

        return ERROR_OK;
}

static int arc_arch_state(struct target *target)
{
        uint32_t pc_value;

        if (debug_level < LOG_LVL_DEBUG)
                return ERROR_OK;

        CHECK_RETVAL(arc_get_register_value(target, "pc", &pc_value));

        LOG_DEBUG("target state: %s;  PC at: 0x%08" PRIx32,
                target_state_name(target),
                pc_value);

        return ERROR_OK;
}

/**
 * See arc_save_context() for reason why we want to dump all regs at once.
 * This however means that if there are dependencies between registers they
 * will not be observable until target will be resumed.
 */
static int arc_restore_context(struct target *target)
{
        int retval = ERROR_OK;
        unsigned int i;
        struct arc_common *arc = target_to_arc(target);
        struct reg *reg_list = arc->core_and_aux_cache->reg_list;

        LOG_DEBUG("Restoring registers values");
        assert(reg_list);

        const uint32_t core_regs_size = arc->num_core_regs  * sizeof(uint32_t);
        const uint32_t aux_regs_size =  arc->num_aux_regs * sizeof(uint32_t);
        uint32_t *core_values = malloc(core_regs_size);
        uint32_t *aux_values = malloc(aux_regs_size);
        uint32_t *core_addrs = malloc(core_regs_size);
        uint32_t *aux_addrs = malloc(aux_regs_size);
        unsigned int core_cnt = 0;
        unsigned int aux_cnt = 0;

        if (!core_values || !core_addrs || !aux_values || !aux_addrs)  {
                LOG_ERROR("Unable to allocate memory");
                retval = ERROR_FAIL;
                goto exit;
        }

        memset(core_values, 0xff, core_regs_size);
        memset(core_addrs, 0xff, core_regs_size);
        memset(aux_values, 0xff, aux_regs_size);
        memset(aux_addrs, 0xff, aux_regs_size);

        for (i = 0; i < arc->num_core_regs; i++) {
                struct reg *reg = &(reg_list[i]);
                struct arc_reg_desc *arc_reg = reg->arch_info;
                if (reg->valid && reg->exist && reg->dirty) {
                        LOG_DEBUG("Will write regnum=%u", i);
                        core_addrs[core_cnt] = arc_reg->arch_num;
                        core_values[core_cnt] = target_buffer_get_u32(target, reg->value);
                        core_cnt += 1;
                }
        }

        for (i = 0; i < arc->num_aux_regs; i++) {
                struct reg *reg = &(reg_list[arc->num_core_regs + i]);
                struct arc_reg_desc *arc_reg = reg->arch_info;
                if (reg->valid && reg->exist && reg->dirty) {
                        LOG_DEBUG("Will write regnum=%lu", arc->num_core_regs + i);
                        aux_addrs[aux_cnt] = arc_reg->arch_num;
                        aux_values[aux_cnt] = target_buffer_get_u32(target, reg->value);
                        aux_cnt += 1;
                }
        }

        /* Write data to target.
         * Check before write, if aux and core count is greater than 0. */
        if (core_cnt > 0) {
                retval = arc_jtag_write_core_reg(&arc->jtag_info, core_addrs, core_cnt, core_values);
                if (ERROR_OK != retval) {
                        LOG_ERROR("Attempt to write to core registers failed.");
                        retval = ERROR_FAIL;
                        goto exit;
                }
        }

        if (aux_cnt > 0) {
                retval = arc_jtag_write_aux_reg(&arc->jtag_info, aux_addrs, aux_cnt, aux_values);
                if (ERROR_OK != retval) {
                        LOG_ERROR("Attempt to write to aux registers failed.");
                        retval = ERROR_FAIL;
                        goto exit;
                }
        }

exit:
        free(core_values);
        free(core_addrs);
        free(aux_values);
        free(aux_addrs);

        return retval;
}

static int arc_enable_interrupts(struct target *target, int enable)
{
        uint32_t value;

        struct arc_common *arc = target_to_arc(target);

        CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG, &value));

        if (enable) {
                /* enable interrupts */
                value |= SET_CORE_ENABLE_INTERRUPTS;
                CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG, value));
                LOG_DEBUG("interrupts enabled");
        } else {
                /* disable interrupts */
                value &= ~SET_CORE_ENABLE_INTERRUPTS;
                CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG, value));
                LOG_DEBUG("interrupts disabled");
        }

        return ERROR_OK;
}

static int arc_resume(struct target *target, int current, target_addr_t address,
        int handle_breakpoints, int debug_execution)
{
        struct arc_common *arc = target_to_arc(target);
        uint32_t resume_pc = 0;
        uint32_t value;
        struct reg *pc = &arc->core_and_aux_cache->reg_list[arc->pc_index_in_cache];

        LOG_DEBUG("current:%i, address:0x%08" TARGET_PRIxADDR ", handle_breakpoints(not supported yet):%i,"
                " debug_execution:%i", current, address, handle_breakpoints, debug_execution);

        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) {
                target_buffer_set_u32(target, pc->value, address);
                pc->dirty = 1;
                pc->valid = 1;
                LOG_DEBUG("Changing the value of current PC to 0x%08" TARGET_PRIxADDR, address);
        }

        if (!current)
                resume_pc = address;
        else
                resume_pc = target_buffer_get_u32(target, pc->value);

        CHECK_RETVAL(arc_restore_context(target));

        LOG_DEBUG("Target resumes from PC=0x%" PRIx32 ", pc.dirty=%i, pc.valid=%i",
                resume_pc, pc->dirty, pc->valid);

        /* check if GDB tells to set our PC where to continue from */
        if ((pc->valid == 1) && (resume_pc == target_buffer_get_u32(target, pc->value))) {
                value = target_buffer_get_u32(target, pc->value);
                LOG_DEBUG("resume Core (when start-core) with PC @:0x%08" PRIx32, value);
                CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_PC_REG, value));
        }

        /* Restore IRQ state if not in debug_execution*/
        if (!debug_execution)
                CHECK_RETVAL(arc_enable_interrupts(target, arc->irq_state));
        else
                CHECK_RETVAL(arc_enable_interrupts(target, !debug_execution));

        target->debug_reason = DBG_REASON_NOTHALTED;

        /* ready to get us going again */
        target->state = TARGET_RUNNING;
        CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG, &value));
        value &= ~SET_CORE_HALT_BIT;        /* clear the HALT bit */
        CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG, value));
        LOG_DEBUG("Core started to run");

        /* registers are now invalid */
        register_cache_invalidate(arc->core_and_aux_cache);

        if (!debug_execution) {
                target->state = TARGET_RUNNING;
                CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_RESUMED));
                LOG_DEBUG("target resumed at 0x%08" PRIx32, resume_pc);
        } else {
                target->state = TARGET_DEBUG_RUNNING;
                CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_DEBUG_RESUMED));
                LOG_DEBUG("target debug resumed at 0x%08" PRIx32, resume_pc);
        }

        return ERROR_OK;
}

static int arc_init_target(struct command_context *cmd_ctx, struct target *target)
{
        CHECK_RETVAL(arc_build_reg_cache(target));
        CHECK_RETVAL(arc_build_bcr_reg_cache(target));
        target->debug_reason = DBG_REASON_DBGRQ;
        return ERROR_OK;
}

static void arc_free_reg_cache(struct reg_cache *cache)
{
        free(cache->reg_list);
        free(cache);
}

static void arc_deinit_target(struct target *target)
{
        struct arc_common *arc = target_to_arc(target);

        LOG_DEBUG("deinitialization of target");
        if (arc->core_aux_cache_built)
                arc_free_reg_cache(arc->core_and_aux_cache);
        if (arc->bcr_cache_built)
                arc_free_reg_cache(arc->bcr_cache);

        struct arc_reg_data_type *type, *n;
        struct arc_reg_desc *desc, *k;

        /* Free arc-specific reg_data_types allocations*/
        list_for_each_entry_safe_reverse(type, n, &arc->reg_data_types, list) {
                if (type->data_type.type_class == REG_TYPE_CLASS_STRUCT) {
                        free(type->reg_type_struct_field);
                        free(type->bitfields);
                        free(type);
                }       else if (type->data_type.type_class == REG_TYPE_CLASS_FLAGS) {
                        free(type->reg_type_flags_field);
                        free(type->bitfields);
                        free(type);
                }
        }

        /* Free standard_gdb_types reg_data_types allocations */
        type = list_first_entry(&arc->reg_data_types, struct arc_reg_data_type, list);
        free(type);

        list_for_each_entry_safe(desc, k, &arc->aux_reg_descriptions, list)
                free_reg_desc(desc);

        list_for_each_entry_safe(desc, k, &arc->core_reg_descriptions, list)
                free_reg_desc(desc);

        list_for_each_entry_safe(desc, k, &arc->bcr_reg_descriptions, list)
                free_reg_desc(desc);

        free(arc);
}


static int arc_target_create(struct target *target, Jim_Interp *interp)
{
        struct arc_common *arc = calloc(1, sizeof(*arc));

        if (!arc) {
                LOG_ERROR("Unable to allocate memory");
                return ERROR_FAIL;
        }

        LOG_DEBUG("Entering");
        CHECK_RETVAL(arc_init_arch_info(target, arc, target->tap));

        return ERROR_OK;
}

/**
 * Write 4-byte instruction to memory. This is like target_write_u32, however
 * in case of little endian ARC instructions are in middle endian format, not
 * little endian, so different type of conversion should be done.
 * Middle endinan: instruction "aabbccdd", stored as "bbaaddcc"
 */
int arc_write_instruction_u32(struct target *target, uint32_t address,
        uint32_t instr)
{
        uint8_t value_buf[4];
        if (!target_was_examined(target)) {
                LOG_ERROR("Target not examined yet");
                return ERROR_FAIL;
        }

        LOG_DEBUG("Address: 0x%08" PRIx32 ", value: 0x%08" PRIx32, address,
                instr);

        if (target->endianness == TARGET_LITTLE_ENDIAN)
                arc_h_u32_to_me(value_buf, instr);
        else
                h_u32_to_be(value_buf, instr);

        CHECK_RETVAL(target_write_buffer(target, address, 4, value_buf));

        return ERROR_OK;
}

/**
 * Read 32-bit instruction from memory. It is like target_read_u32, however in
 * case of little endian ARC instructions are in middle endian format, so
 * different type of conversion should be done.
 */
int arc_read_instruction_u32(struct target *target, uint32_t address,
                uint32_t *value)
{
        uint8_t value_buf[4];

        if (!target_was_examined(target)) {
                LOG_ERROR("Target not examined yet");
                return ERROR_FAIL;
        }

        *value = 0;
        CHECK_RETVAL(target_read_buffer(target, address, 4, value_buf));

        if (target->endianness == TARGET_LITTLE_ENDIAN)
                *value = arc_me_to_h_u32(value_buf);
        else
                *value = be_to_h_u32(value_buf);

        LOG_DEBUG("Address: 0x%08" PRIx32 ", value: 0x%08" PRIx32, address,
                *value);

        return ERROR_OK;
}

static int arc_set_breakpoint(struct target *target,
                struct breakpoint *breakpoint)
{

        if (breakpoint->set) {
                LOG_WARNING("breakpoint already set");
                return ERROR_OK;
        }

        if (breakpoint->type == BKPT_SOFT) {
                LOG_DEBUG("bpid: %" PRIu32, breakpoint->unique_id);

                if (breakpoint->length == 4) {
                        uint32_t verify = 0xffffffff;

                        CHECK_RETVAL(target_read_buffer(target, breakpoint->address, breakpoint->length,
                                        breakpoint->orig_instr));

                        CHECK_RETVAL(arc_write_instruction_u32(target, breakpoint->address,
                                        ARC_SDBBP_32));

                        CHECK_RETVAL(arc_read_instruction_u32(target, breakpoint->address, &verify));

                        if (verify != ARC_SDBBP_32) {
                                LOG_ERROR("Unable to set 32bit breakpoint at address @0x%" TARGET_PRIxADDR
                                                " - check that memory is read/writable", breakpoint->address);
                                return ERROR_FAIL;
                        }
                } else if (breakpoint->length == 2) {
                        uint16_t verify = 0xffff;

                        CHECK_RETVAL(target_read_buffer(target, breakpoint->address, breakpoint->length,
                                        breakpoint->orig_instr));
                        CHECK_RETVAL(target_write_u16(target, breakpoint->address, ARC_SDBBP_16));

                        CHECK_RETVAL(target_read_u16(target, breakpoint->address, &verify));
                        if (verify != ARC_SDBBP_16) {
                                LOG_ERROR("Unable to set 16bit breakpoint at address @0x%" TARGET_PRIxADDR
                                                " - check that memory is read/writable", breakpoint->address);
                                return ERROR_FAIL;
                        }
                } else {
                        LOG_ERROR("Invalid breakpoint length: target supports only 2 or 4");
                        return ERROR_COMMAND_ARGUMENT_INVALID;
                }

                breakpoint->set = 64; /* Any nice value but 0 */
        } else if (breakpoint->type == BKPT_HARD) {
                LOG_DEBUG("Hardware breakpoints are not supported yet!");
                return ERROR_FAIL;
        } else {
                LOG_DEBUG("ERROR: setting unknown breakpoint type");
                return ERROR_FAIL;
        }
        /* core instruction cache is now invalid,
         * TODO: add cache invalidation function here (when implemented). */

        return ERROR_OK;
}

static int arc_unset_breakpoint(struct target *target,
                struct breakpoint *breakpoint)
{
        int retval = ERROR_OK;

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

        if (breakpoint->type == BKPT_SOFT) {
                /* restore original instruction (kept in target endianness) */
                LOG_DEBUG("bpid: %" PRIu32, breakpoint->unique_id);
                if (breakpoint->length == 4) {
                        uint32_t current_instr;

                        /* check that user program has not modified breakpoint instruction */
                        CHECK_RETVAL(arc_read_instruction_u32(target, breakpoint->address, &current_instr));

                        if (current_instr == ARC_SDBBP_32) {
                                retval = target_write_buffer(target, breakpoint->address,
                                        breakpoint->length, breakpoint->orig_instr);
                                if (retval != ERROR_OK)
                                        return retval;
                        } else {
                                LOG_WARNING("Software breakpoint @0x%" TARGET_PRIxADDR
                                        " has been overwritten outside of debugger."
                                        "Expected: @0x%" PRIx32 ", got: @0x%" PRIx32,
                                        breakpoint->address, ARC_SDBBP_32, current_instr);
                        }
                } else if (breakpoint->length == 2) {
                        uint16_t current_instr;

                        /* check that user program has not modified breakpoint instruction */
                        CHECK_RETVAL(target_read_u16(target, breakpoint->address, &current_instr));
                        if (current_instr == ARC_SDBBP_16) {
                                retval = target_write_buffer(target, breakpoint->address,
                                        breakpoint->length, breakpoint->orig_instr);
                                if (retval != ERROR_OK)
                                        return retval;
                        } else {
                                LOG_WARNING("Software breakpoint @0x%" TARGET_PRIxADDR
                                        " has been overwritten outside of debugger. "
                                        "Expected: 0x%04x, got: 0x%04" PRIx16,
                                        breakpoint->address, ARC_SDBBP_16, current_instr);
                        }
                } else {
                        LOG_ERROR("Invalid breakpoint length: target supports only 2 or 4");
                        return ERROR_COMMAND_ARGUMENT_INVALID;
                }
                breakpoint->set = 0;

        }       else if (breakpoint->type == BKPT_HARD) {
                        LOG_WARNING("Hardware breakpoints are not supported yet!");
                        return ERROR_FAIL;
        } else {
                        LOG_DEBUG("ERROR: unsetting unknown breakpoint type");
                        return ERROR_FAIL;
        }

        /* core instruction cache is now invalid.
         * TODO: Add cache invalidation function */

        return retval;
}


static int arc_add_breakpoint(struct target *target, struct breakpoint *breakpoint)
{
        if (target->state == TARGET_HALTED) {
                return arc_set_breakpoint(target, breakpoint);

        } else {
                LOG_WARNING(" > core was not halted, please try again.");
                return ERROR_TARGET_NOT_HALTED;
        }
}

static int arc_remove_breakpoint(struct target *target,
        struct breakpoint *breakpoint)
{
        if (target->state == TARGET_HALTED) {
                if (breakpoint->set)
                        CHECK_RETVAL(arc_unset_breakpoint(target, breakpoint));
        } else {
                LOG_WARNING("target not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        return ERROR_OK;
}

/* Helper function which swiches core to single_step mode by
 * doing aux r/w operations.  */
int arc_config_step(struct target *target, int enable_step)
{
        uint32_t value;

        struct arc_common *arc = target_to_arc(target);

        /* enable core debug step mode */
        if (enable_step) {
                CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG,
                        &value));
                value &= ~SET_CORE_AE_BIT; /* clear the AE bit */
                CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_STATUS32_REG,
                        value));
                LOG_DEBUG(" [status32:0x%08" PRIx32 "]", value);

                /* Doing read-modify-write, because DEBUG might contain manually set
                 * bits like UB or ED, which should be preserved.  */
                CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info,
                                        AUX_DEBUG_REG, &value));
                value |= SET_CORE_SINGLE_INSTR_STEP; /* set the IS bit */
                CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_DEBUG_REG,
                        value));
                LOG_DEBUG("core debug step mode enabled [debug-reg:0x%08" PRIx32 "]", value);

        } else {        /* disable core debug step mode */
                CHECK_RETVAL(arc_jtag_read_aux_reg_one(&arc->jtag_info, AUX_DEBUG_REG,
                        &value));
                value &= ~SET_CORE_SINGLE_INSTR_STEP; /* clear the IS bit */
                CHECK_RETVAL(arc_jtag_write_aux_reg_one(&arc->jtag_info, AUX_DEBUG_REG,
                        value));
                LOG_DEBUG("core debug step mode disabled");
        }

        return ERROR_OK;
}

int arc_step(struct target *target, int current, target_addr_t address,
        int handle_breakpoints)
{
        /* get pointers to arch-specific information */
        struct arc_common *arc = target_to_arc(target);
        struct breakpoint *breakpoint = NULL;
        struct reg *pc = &(arc->core_and_aux_cache->reg_list[arc->pc_index_in_cache]);

        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(pc->value, 0, 32, address);
                pc->dirty = 1;
                pc->valid = 1;
        }

        LOG_DEBUG("Target steps one instruction from PC=0x%" PRIx32,
                buf_get_u32(pc->value, 0, 32));

        /* the front-end may request us not to handle breakpoints */
        if (handle_breakpoints) {
                breakpoint = breakpoint_find(target, buf_get_u32(pc->value, 0, 32));
                if (breakpoint)
                        CHECK_RETVAL(arc_unset_breakpoint(target, breakpoint));
        }

        /* restore context */
        CHECK_RETVAL(arc_restore_context(target));

        target->debug_reason = DBG_REASON_SINGLESTEP;

        CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_RESUMED));

        /* disable interrupts while stepping */
        CHECK_RETVAL(arc_enable_interrupts(target, 0));

        /* do a single step */
        CHECK_RETVAL(arc_config_step(target, 1));

        /* make sure we done our step */
        alive_sleep(1);

        /* registers are now invalid */
        register_cache_invalidate(arc->core_and_aux_cache);

        if (breakpoint)
                CHECK_RETVAL(arc_set_breakpoint(target, breakpoint));

        LOG_DEBUG("target stepped ");

        target->state = TARGET_HALTED;

        /* Saving context */
        CHECK_RETVAL(arc_debug_entry(target));
        CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_HALTED));

        return ERROR_OK;
}



/* ARC v2 target */
struct target_type arcv2_target = {
        .name = "arcv2",

        .poll = arc_poll,

        .arch_state = arc_arch_state,

        /* TODO That seems like something similiar to metaware hostlink, so perhaps
         * we can exploit this in the future. */
        .target_request_data = NULL,

        .halt = arc_halt,
        .resume = arc_resume,
        .step = arc_step,

        .assert_reset = arc_assert_reset,
        .deassert_reset = arc_deassert_reset,

        /* TODO Implement soft_reset_halt */
        .soft_reset_halt = NULL,

        .get_gdb_reg_list = arc_get_gdb_reg_list,

        .read_memory = arc_mem_read,
        .write_memory = arc_mem_write,
        .checksum_memory = NULL,
        .blank_check_memory = NULL,

        .add_breakpoint = arc_add_breakpoint,
        .add_context_breakpoint = NULL,
        .add_hybrid_breakpoint = NULL,
        .remove_breakpoint = arc_remove_breakpoint,
        .add_watchpoint = NULL,
        .remove_watchpoint = NULL,
        .hit_watchpoint = NULL,

        .run_algorithm = NULL,
        .start_algorithm = NULL,
        .wait_algorithm = NULL,

        .commands = arc_monitor_command_handlers,

        .target_create = arc_target_create,
        .init_target = arc_init_target,
        .deinit_target = arc_deinit_target,
        .examine = arc_examine,

        .virt2phys = NULL,
        .read_phys_memory = NULL,
        .write_phys_memory = NULL,
        .mmu = NULL,
};