Remove FSF address from GPL notices

[openocd.git] / src / target / arm946e.c

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   Copyright (C) 2010 by Drasko DRASKOVIC                                *
 *   drasko.draskovic@gmail.com                                            *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 ***************************************************************************/

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

#include "arm946e.h"
#include "target_type.h"
#include "arm_opcodes.h"

#include "breakpoints.h"

#if 0
#define _DEBUG_INSTRUCTION_EXECUTION_
#endif

#define NB_CACHE_WAYS 4

#define CP15_CTL                0x02
#define CP15_CTL_DCACHE (1<<2)
#define CP15_CTL_ICACHE (1<<12)

/**
 * flag to give info about cache manipulation during debug :
 * "0"  -       cache lines are invalidated "on the fly", for affected addresses.
 *                      This is prefered from performance point of view.
 * "1"  -       cache is invalidated and switched off on debug_entry, and switched back on on restore.
 *                      It is kept off during debugging.
 */
static uint8_t arm946e_preserve_cache;

int arm946e_post_debug_entry(struct target *target);
void arm946e_pre_restore_context(struct target *target);
static int arm946e_read_cp15(struct target *target, int reg_addr, uint32_t *value);

int arm946e_init_arch_info(struct target *target,
        struct arm946e_common *arm946e,
        struct jtag_tap *tap)
{
        struct arm7_9_common *arm7_9 = &arm946e->arm7_9_common;

        /* initialize arm7/arm9 specific info (including armv4_5) */
        arm9tdmi_init_arch_info(target, arm7_9, tap);

        arm946e->common_magic = ARM946E_COMMON_MAGIC;

        /**
         * The ARM946E-S implements the ARMv5TE architecture which
         * has the BKPT instruction, so we don't have to use a watchpoint comparator
         */
        arm7_9->arm_bkpt = ARMV5_BKPT(0x0);
        arm7_9->thumb_bkpt = ARMV5_T_BKPT(0x0) & 0xffff;


        arm7_9->post_debug_entry = arm946e_post_debug_entry;
        arm7_9->pre_restore_context = arm946e_pre_restore_context;

        /**
         * disabling linefills leads to lockups, so keep them enabled for now
         * this doesn't affect correctness, but might affect timing issues, if
         * important data is evicted from the cache during the debug session
         */
        arm946e_preserve_cache = 0;

        /* override hw single-step capability from ARM9TDMI */
        /* arm7_9->has_single_step = 1; */

        return ERROR_OK;
}

static int arm946e_target_create(struct target *target, Jim_Interp *interp)
{
        struct arm946e_common *arm946e = calloc(1, sizeof(struct arm946e_common));

        arm946e_init_arch_info(target, arm946e, target->tap);

        return ERROR_OK;
}

static int arm946e_verify_pointer(struct command_context *cmd_ctx,
        struct arm946e_common *arm946e)
{
        if (arm946e->common_magic != ARM946E_COMMON_MAGIC) {
                command_print(cmd_ctx, "target is not an ARM946");
                return ERROR_TARGET_INVALID;
        }
        return ERROR_OK;
}

/*
 * Update cp15_control_reg, saved on debug_entry.
 */
static void arm946e_update_cp15_caches(struct target *target, uint32_t value)
{
        struct arm946e_common *arm946e = target_to_arm946(target);
        arm946e->cp15_control_reg = (arm946e->cp15_control_reg & ~(CP15_CTL_DCACHE|CP15_CTL_ICACHE))
                | (value & (CP15_CTL_DCACHE|CP15_CTL_ICACHE));
}

/*
 * REVISIT:  The "read_cp15" and "write_cp15" commands could hook up
 * to eventual mrc() and mcr() routines ... the reg_addr values being
 * constructed (for CP15 only) from Opcode_1, Opcode_2, and CRn values.
 * See section 7.3 of the ARM946E-S TRM.
 */
static int arm946e_read_cp15(struct target *target, int reg_addr, uint32_t *value)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        struct scan_field fields[3];
        uint8_t reg_addr_buf = reg_addr & 0x3f;
        uint8_t nr_w_buf = 0;

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

        fields[0].num_bits = 32;
        /* REVISIT: table 7-2 shows that bits 31-31 need to be
         * specified for accessing BIST registers ...
         */
        fields[0].out_value = NULL;
        fields[0].in_value = NULL;

        fields[1].num_bits = 6;
        fields[1].out_value = &reg_addr_buf;
        fields[1].in_value = NULL;

        fields[2].num_bits = 1;
        fields[2].out_value = &nr_w_buf;
        fields[2].in_value = NULL;

        jtag_add_dr_scan(jtag_info->tap, 3, fields, TAP_IDLE);

        fields[0].in_value = (uint8_t *)value;
        jtag_add_dr_scan(jtag_info->tap, 3, fields, TAP_IDLE);

        jtag_add_callback(arm_le_to_h_u32, (jtag_callback_data_t)value);

#ifdef _DEBUG_INSTRUCTION_EXECUTION_
        LOG_DEBUG("addr: 0x%x value: %8.8x", reg_addr, *value);
#endif

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

        return ERROR_OK;
}

int arm946e_write_cp15(struct target *target, int reg_addr, uint32_t value)
{
        int retval = ERROR_OK;
        struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
        struct arm_jtag *jtag_info = &arm7_9->jtag_info;
        struct scan_field fields[3];
        uint8_t reg_addr_buf = reg_addr & 0x3f;
        uint8_t nr_w_buf = 1;
        uint8_t value_buf[4];

        buf_set_u32(value_buf, 0, 32, value);

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

        fields[0].num_bits = 32;
        fields[0].out_value = value_buf;
        fields[0].in_value = NULL;

        fields[1].num_bits = 6;
        fields[1].out_value = &reg_addr_buf;
        fields[1].in_value = NULL;

        fields[2].num_bits = 1;
        fields[2].out_value = &nr_w_buf;
        fields[2].in_value = NULL;

        jtag_add_dr_scan(jtag_info->tap, 3, fields, TAP_IDLE);

#ifdef _DEBUG_INSTRUCTION_EXECUTION_
        LOG_DEBUG("addr: 0x%x value: %8.8x", reg_addr, value);
#endif

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

        return ERROR_OK;
}

#define GET_ICACHE_SIZE  6
#define GET_DCACHE_SIZE 18

/*
 * \param target struct target pointer
 * \param idsel  select GET_ICACHE_SIZE or GET_DCACHE_SIZE
 * \returns      cache size, given in bytes
 */
static uint32_t arm946e_cp15_get_csize(struct target *target, int idsel)
{
        struct arm946e_common *arm946e = target_to_arm946(target);
        uint32_t csize = arm946e->cp15_cache_info;
        if (csize == 0) {
                if (arm946e_read_cp15(target, 0x01, &csize) == ERROR_OK)
                        arm946e->cp15_cache_info = csize;
        }
        if (csize & (1<<(idsel-4)))     /* cache absent */
                return 0;
        csize = (csize >> idsel) & 0x0F;
        return csize ? 1 << (12 + (csize-3)) : 0;
}

uint32_t arm946e_invalidate_whole_dcache(struct target *target)
{
        uint32_t csize = arm946e_cp15_get_csize(target, GET_DCACHE_SIZE);
        if (csize == 0)
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;

        /* One line (index) is 32 bytes (8 words) long, 4-way assoc
         * ARM DDI 0201D, Section 3.3.5
         */
        int nb_idx = (csize / (4*8*NB_CACHE_WAYS));     /* gives nb of lines (indexes) in the cache */

        /* Loop for all segmentde (i.e. ways) */
        uint32_t seg;
        for (seg = 0; seg < NB_CACHE_WAYS; seg++) {
                /* Loop for all indexes */
                int idx;
                for (idx = 0; idx < nb_idx; idx++) {
                        /* Form and write cp15 index (segment + line idx) */
                        uint32_t cp15_idx = seg << 30 | idx << 5;
                        int retval = arm946e_write_cp15(target, 0x3a, cp15_idx);
                        if (retval != ERROR_OK) {
                                LOG_DEBUG("ERROR writing index");
                                return retval;
                        }

                        /* Read dtag */
                        uint32_t dtag;
                        arm946e_read_cp15(target, 0x16, (uint32_t *) &dtag);

                        /* Check cache line VALID bit */
                        if (!(dtag >> 4 & 0x1))
                                continue;

                        /* Clean data cache line */
                        retval = arm946e_write_cp15(target, 0x35, 0x1);
                        if (retval != ERROR_OK) {
                                LOG_DEBUG("ERROR cleaning cache line");
                                return retval;
                        }

                        /* Flush data cache line */
                        retval = arm946e_write_cp15(target, 0x1a, 0x1);
                        if (retval != ERROR_OK) {
                                LOG_DEBUG("ERROR flushing cache line");
                                return retval;
                        }
                }
        }

        return ERROR_OK;
}

uint32_t arm946e_invalidate_whole_icache(struct target *target)
{
        /* Check cache presence before flushing - avoid undefined behavior */
        uint32_t csize = arm946e_cp15_get_csize(target, GET_ICACHE_SIZE);
        if (csize == 0)
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;

        LOG_DEBUG("FLUSHING I$");
        /**
         *  Invalidate (flush) I$
         *  mcr 15, 0, r0, cr7, cr5, {0}
         */
        int retval = arm946e_write_cp15(target, 0x0f, 0x1);
        if (retval != ERROR_OK) {
                LOG_DEBUG("ERROR flushing I$");
                return retval;
        }

        return ERROR_OK;
}

int arm946e_post_debug_entry(struct target *target)
{
        uint32_t ctr_reg = 0x0;
        uint32_t retval = ERROR_OK;
        struct arm946e_common *arm946e = target_to_arm946(target);

        /* See if CACHES are enabled, and save that info
         * in the context bits, so that arm946e_pre_restore_context() can use them */
        arm946e_read_cp15(target, CP15_CTL, (uint32_t *) &ctr_reg);

        /* Save control reg in the context */
        arm946e->cp15_control_reg = ctr_reg;

        if (arm946e_preserve_cache) {
                if (ctr_reg & CP15_CTL_DCACHE) {
                        /* Clean and flush D$ */
                        arm946e_invalidate_whole_dcache(target);

                        /* Disable D$ */
                        ctr_reg &= ~CP15_CTL_DCACHE;
                }

                if (ctr_reg & CP15_CTL_ICACHE) {
                        /* Flush I$ */
                        arm946e_invalidate_whole_icache(target);

                        /* Disable I$ */
                        ctr_reg &= ~CP15_CTL_ICACHE;
                }

                /* Write the new configuration */
                retval = arm946e_write_cp15(target, CP15_CTL, ctr_reg);
                if (retval != ERROR_OK) {
                        LOG_DEBUG("ERROR disabling cache");
                        return retval;
                }
        }       /* if preserve_cache */

        return ERROR_OK;
}

void arm946e_pre_restore_context(struct target *target)
{
        uint32_t ctr_reg = 0x0;
        uint32_t retval;

        if (arm946e_preserve_cache) {
                struct arm946e_common *arm946e = target_to_arm946(target);
                /* Get the contents of the CTR reg */
                arm946e_read_cp15(target, CP15_CTL, (uint32_t *) &ctr_reg);

                /**
                 * Read-modify-write CP15 control
                 * to reenable I/D-cache operation
                 * NOTE: It is not possible to disable cache by CP15.
                 * if arm946e_preserve_cache debugging flag enabled.
                 */
                ctr_reg |= arm946e->cp15_control_reg & (CP15_CTL_DCACHE|CP15_CTL_ICACHE);

                /* Write the new configuration */
                retval = arm946e_write_cp15(target, CP15_CTL, ctr_reg);
                if (retval != ERROR_OK)
                        LOG_DEBUG("ERROR enabling cache");
        }       /* if preserve_cache */
}

uint32_t arm946e_invalidate_dcache(struct target *target, uint32_t address,
        uint32_t size, uint32_t count)
{
        uint32_t cur_addr = 0x0;
        uint32_t cp15_idx, set, way, dtag;
        uint32_t i = 0;
        int retval;

        for (i = 0; i < count*size; i++) {
                cur_addr = address + i;


                set = (cur_addr >> 5) & 0xff;   /* set field is 8 bits long */

                for (way = 0; way < NB_CACHE_WAYS; way++) {
                        /**
                         * Find if the affected address is kept in the cache.
                         * Because JTAG Scan Chain 15 offers limited approach,
                         * we have to loop through all cache ways (segments) and
                         * read cache tags, then compare them with with address.
                         */

                        /* Form and write cp15 index (segment + line idx) */
                        cp15_idx = way << 30 | set << 5;
                        retval = arm946e_write_cp15(target, 0x3a, cp15_idx);
                        if (retval != ERROR_OK) {
                                LOG_DEBUG("ERROR writing index");
                                return retval;
                        }

                        /* Read dtag */
                        arm946e_read_cp15(target, 0x16, (uint32_t *) &dtag);

                        /* Check cache line VALID bit */
                        if (!(dtag >> 4 & 0x1))
                                continue;

                        /* If line is valid and corresponds to affected address - invalidate it */
                        if (dtag >> 5 == cur_addr >> 5) {
                                /* Clean data cache line */
                                retval = arm946e_write_cp15(target, 0x35, 0x1);
                                if (retval != ERROR_OK) {
                                        LOG_DEBUG("ERROR cleaning cache line");
                                        return retval;
                                }

                                /* Flush data cache line */
                                retval = arm946e_write_cp15(target, 0x1c, 0x1);
                                if (retval != ERROR_OK) {
                                        LOG_DEBUG("ERROR flushing cache line");
                                        return retval;
                                }

                                break;
                        }
                }       /* loop through all 4 ways */
        }       /* loop through all addresses */

        return ERROR_OK;
}

uint32_t arm946e_invalidate_icache(struct target *target, uint32_t address,
        uint32_t size, uint32_t count)
{
        uint32_t cur_addr = 0x0;
        uint32_t cp15_idx, set, way, itag;
        uint32_t i = 0;
        int retval;

        for (i = 0; i < count*size; i++) {
                cur_addr = address + i;

                set = (cur_addr >> 5) & 0xff;   /* set field is 8 bits long */

                for (way = 0; way < NB_CACHE_WAYS; way++) {
                        /* Form and write cp15 index (segment + line idx) */
                        cp15_idx = way << 30 | set << 5;
                        retval = arm946e_write_cp15(target, 0x3a, cp15_idx);
                        if (retval != ERROR_OK) {
                                LOG_DEBUG("ERROR writing index");
                                return retval;
                        }

                        /* Read itag */
                        arm946e_read_cp15(target, 0x17, (uint32_t *) &itag);

                        /* Check cache line VALID bit */
                        if (!(itag >> 4 & 0x1))
                                continue;

                        /* If line is valid and corresponds to affected address - invalidate it */
                        if (itag >> 5 == cur_addr >> 5) {
                                /* Flush I$ line */
                                retval = arm946e_write_cp15(target, 0x1d, 0x0);
                                if (retval != ERROR_OK) {
                                        LOG_DEBUG("ERROR flushing cache line");
                                        return retval;
                                }

                                break;
                        }
                }       /* way loop */
        }       /* addr loop */

        return ERROR_OK;
}

/** Writes a buffer, in the specified word size, with current MMU settings. */
int arm946e_write_memory(struct target *target, uint32_t address,
        uint32_t size, uint32_t count, const uint8_t *buffer)
{
        int retval;

        LOG_DEBUG("-");

        struct arm946e_common *arm946e = target_to_arm946(target);
        /* Invalidate D$ if it is ON */
        if (!arm946e_preserve_cache && (arm946e->cp15_control_reg & CP15_CTL_DCACHE))
                arm946e_invalidate_dcache(target, address, size, count);

        /**
         * Write memory
         */
        retval = arm7_9_write_memory_opt(target, address, size, count, buffer);
        if (retval != ERROR_OK)
                return retval;

        /* *
         * Invalidate I$ if it is ON.
         *
         * D$ has been cleaned and flushed before mem write thus forcing it to behave like write-through,
         * because arm7_9_write_memory() has seen non-valid bit in D$
         * and wrote data into physical RAM (without touching or allocating the cache line).
         * From ARM946ES Technical Reference Manual we can see that it uses "allocate on read-miss"
         * policy for both I$ and D$ (Chapter 3.2 and 3.3)
         *
         * Explanation :
         * "ARM system developer's guide: designing and optimizing system software" by
         * Andrew N. Sloss, Dominic Symes and Chris Wright,
         * Chapter 12.3.3 Allocating Policy on a Cache Miss :
         * A read allocate on cache miss policy allocates a cache line only during a read from main memory.
         * If the victim cache line contains valid data, then it is written to main memory before the cache line
         * is filled with new data.
         * Under this strategy, a write of new data to memory does not update the contents of the cache memory
         * unless a cache line was allocated on a previous read from main memory.
         * If the cache line contains valid data, then the write updates the cache and may update the main memory if
         * the cache write policy is write-through.
         * If the data is not in the cache, the controller writes to main memory only.
         */
        if (!arm946e_preserve_cache && (arm946e->cp15_control_reg & CP15_CTL_ICACHE))
                arm946e_invalidate_icache(target, address, size, count);

        return ERROR_OK;

}

int arm946e_read_memory(struct target *target, uint32_t address,
        uint32_t size, uint32_t count, uint8_t *buffer)
{
        int retval;

        LOG_DEBUG("-");

        retval = arm7_9_read_memory(target, address, size, count, buffer);
        if (retval != ERROR_OK)
                return retval;

        return ERROR_OK;
}

static int jim_arm946e_cp15(Jim_Interp *interp, int argc, Jim_Obj * const *argv)
{
        /* one or two arguments, access a single register (write if second argument is given) */
        if (argc < 2 || argc > 3) {
                Jim_WrongNumArgs(interp, 1, argv, "addr [value]");
                return JIM_ERR;
        }

        struct command_context *cmd_ctx = current_command_context(interp);
        assert(cmd_ctx != NULL);

        struct target *target = get_current_target(cmd_ctx);
        if (target == NULL) {
                LOG_ERROR("arm946e: no current target");
                return JIM_ERR;
        }

        struct arm946e_common *arm946e = target_to_arm946(target);
        int retval = arm946e_verify_pointer(cmd_ctx, arm946e);
        if (retval != ERROR_OK)
                return JIM_ERR;

        if (target->state != TARGET_HALTED) {
                command_print(cmd_ctx, "target %s must be stopped for \"cp15\" command", target_name(target));
                return JIM_ERR;
        }

        long l;
        uint32_t address;
        retval = Jim_GetLong(interp, argv[1], &l);
        address = l;
        if (JIM_OK != retval)
                return retval;

        if (argc == 2) {
                uint32_t value;
                retval = arm946e_read_cp15(target, address, &value);
                if (retval != ERROR_OK) {
                        command_print(cmd_ctx, "%s cp15 reg %" PRIi32 " access failed", target_name(target), address);
                        return JIM_ERR;
                }
                retval = jtag_execute_queue();
                if (retval != ERROR_OK)
                        return JIM_ERR;
                char buf[20];
                sprintf(buf, "0x%08" PRIx32, value);
                /* Return value in hex format */
                Jim_SetResultString(interp, buf, -1);
        } else if (argc == 3) {
                uint32_t value;
                retval = Jim_GetLong(interp, argv[2], &l);
                value = l;
                if (JIM_OK != retval)
                        return retval;
                retval = arm946e_write_cp15(target, address, value);
                if (retval != ERROR_OK) {
                        command_print(cmd_ctx, "%s cp15 reg %" PRIi32 " access failed", target_name(target), address);
                        return JIM_ERR;
                }
                if (address == CP15_CTL)
                        arm946e_update_cp15_caches(target, value);
        }

        return JIM_OK;
}

COMMAND_HANDLER(arm946e_handle_idcache)
{
        if (CMD_ARGC > 1)
                return ERROR_COMMAND_SYNTAX_ERROR;

        int retval;
        struct target *target = get_current_target(CMD_CTX);
        struct arm946e_common *arm946e = target_to_arm946(target);

        retval = arm946e_verify_pointer(CMD_CTX, arm946e);
        if (retval != ERROR_OK)
                return retval;

        if (target->state != TARGET_HALTED) {
                command_print(CMD_CTX, "target must be stopped for \"%s\" command", CMD_NAME);
                return ERROR_TARGET_NOT_HALTED;
        }

        bool icache = (strcmp(CMD_NAME, "icache") == 0);
        uint32_t csize = arm946e_cp15_get_csize(target, icache ? GET_ICACHE_SIZE : GET_DCACHE_SIZE) / 1024;
        if (CMD_ARGC == 0) {
                bool  bena = ((arm946e->cp15_control_reg & (icache ? CP15_CTL_ICACHE : CP15_CTL_DCACHE)) != 0)
                          && (arm946e->cp15_control_reg & 0x1);
                if (csize == 0)
                        command_print(CMD_CTX, "%s-cache absent", icache ? "I" : "D");
                else
                        command_print(CMD_CTX, "%s-cache size: %" PRIu32 "K, %s",
                                      icache ? "I" : "D", csize, bena ? "enabled" : "disabled");
                return ERROR_OK;
        }

        bool flush = false;
        bool enable = false;
        retval = command_parse_bool_arg(CMD_ARGV[0], &enable);
        if (retval == ERROR_COMMAND_SYNTAX_ERROR) {
                if (strcmp(CMD_ARGV[0], "flush") == 0) {
                        flush = true;
                        retval = ERROR_OK;
                } else
                        return retval;
        }

        /* Do not invalidate or change state, if cache is absent */
        if (csize == 0) {
                command_print(CMD_CTX, "%s-cache absent, '%s' operation undefined", icache ? "I" : "D", CMD_ARGV[0]);
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }

        /* NOTE: flushing entire cache will not preserve lock-down cache regions */
        if (icache) {
                if ((arm946e->cp15_control_reg & CP15_CTL_ICACHE) && !enable)
                        retval = arm946e_invalidate_whole_icache(target);
        } else {
                if ((arm946e->cp15_control_reg & CP15_CTL_DCACHE) && !enable)
                        retval = arm946e_invalidate_whole_dcache(target);
        }

        if (retval != ERROR_OK || flush)
                return retval;

        uint32_t value;
        retval = arm946e_read_cp15(target, CP15_CTL, &value);
        if (retval != ERROR_OK)
                return retval;

        uint32_t vnew = value;
        uint32_t cmask = icache ? CP15_CTL_ICACHE : CP15_CTL_DCACHE;
        if (enable) {
                if ((value & 0x1) == 0)
                        LOG_WARNING("arm946e: MPU must be enabled for cache to operate");
                vnew |= cmask;
        } else
                vnew &= ~cmask;

        if (vnew == value)
                return ERROR_OK;

        retval = arm946e_write_cp15(target, CP15_CTL, vnew);
        if (retval != ERROR_OK)
                return retval;

        arm946e_update_cp15_caches(target, vnew);
        return ERROR_OK;
}

static const struct command_registration arm946e_exec_command_handlers[] = {
        {
                .name = "cp15",
                .jim_handler = jim_arm946e_cp15,
                .mode = COMMAND_EXEC,
                .usage = "regnum [value]",
                .help = "read/modify cp15 register",
        },
        {
                .name = "icache",
                .handler = arm946e_handle_idcache,
                .mode = COMMAND_EXEC,
                .usage = "['enable'|'disable'|'flush']",
                .help = "I-cache info and operations",
        },
        {
                .name = "dcache",
                .handler = arm946e_handle_idcache,
                .mode = COMMAND_EXEC,
                .usage = "['enable'|'disable'|'flush']",
                .help = "D-cache info and operations",
        },
        COMMAND_REGISTRATION_DONE
};

const struct command_registration arm946e_command_handlers[] = {
        {
                .chain = arm9tdmi_command_handlers,
        },
        {
                .name = "arm946e",
                .mode = COMMAND_ANY,
                .help = "arm946e command group",
                .usage = "",
                .chain = arm946e_exec_command_handlers,
        },
        COMMAND_REGISTRATION_DONE
};

/** Holds methods for ARM946 targets. */
struct target_type arm946e_target = {
        .name = "arm946e",

        .poll = arm7_9_poll,
        .arch_state = arm_arch_state,

        .target_request_data = arm7_9_target_request_data,

        .halt = arm7_9_halt,
        .resume = arm7_9_resume,
        .step = arm7_9_step,

        .assert_reset = arm7_9_assert_reset,
        .deassert_reset = arm7_9_deassert_reset,
        .soft_reset_halt = arm7_9_soft_reset_halt,

        .get_gdb_reg_list = arm_get_gdb_reg_list,

        /* .read_memory = arm7_9_read_memory, */
        /* .write_memory = arm7_9_write_memory, */
        .read_memory = arm946e_read_memory,
        .write_memory = arm946e_write_memory,

        .checksum_memory = arm_checksum_memory,
        .blank_check_memory = arm_blank_check_memory,

        .run_algorithm = armv4_5_run_algorithm,

        .add_breakpoint = arm7_9_add_breakpoint,
        .remove_breakpoint = arm7_9_remove_breakpoint,
        /* .add_breakpoint = arm946e_add_breakpoint, */
        /* .remove_breakpoint = arm946e_remove_breakpoint, */

        .add_watchpoint = arm7_9_add_watchpoint,
        .remove_watchpoint = arm7_9_remove_watchpoint,

        .commands = arm946e_command_handlers,
        .target_create = arm946e_target_create,
        .init_target = arm9tdmi_init_target,
        .examine = arm7_9_examine,
        .check_reset = arm7_9_check_reset,
};