jtag: retire tap field

[openocd.git] / src / target / arm11.c

/***************************************************************************
 *   Copyright (C) 2008 digenius technology GmbH.                          *
 *   Michael Bruck                                                         *
 *                                                                         *
 *   Copyright (C) 2008,2009 Oyvind Harboe oyvind.harboe@zylin.com         *
 *                                                                         *
 *   Copyright (C) 2008 Georg Acher <acher@in.tum.de>                      *
 *                                                                         *
 *   Copyright (C) 2009 David Brownell                                     *
 *                                                                         *
 *   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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

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

#include "etm.h"
#include "breakpoints.h"
#include "arm11_dbgtap.h"
#include "arm_simulator.h"
#include <helper/time_support.h>
#include "target_type.h"
#include "algorithm.h"
#include "register.h"
#include "arm_opcodes.h"


#if 0
#define _DEBUG_INSTRUCTION_EXECUTION_
#endif


static int arm11_step(struct target *target, int current,
                uint32_t address, int handle_breakpoints);


/** Check and if necessary take control of the system
 *
 * \param arm11         Target state variable.
 */
static int arm11_check_init(struct arm11_common *arm11)
{
        CHECK_RETVAL(arm11_read_DSCR(arm11));

        if (!(arm11->dscr & DSCR_HALT_DBG_MODE))
        {
                LOG_DEBUG("DSCR %08x", (unsigned) arm11->dscr);
                LOG_DEBUG("Bringing target into debug mode");

                arm11->dscr |= DSCR_HALT_DBG_MODE;
                arm11_write_DSCR(arm11, arm11->dscr);

                /* add further reset initialization here */

                arm11->simulate_reset_on_next_halt = true;

                if (arm11->dscr & DSCR_CORE_HALTED)
                {
                        /** \todo TODO: this needs further scrutiny because
                          * arm11_debug_entry() never gets called.  (WHY NOT?)
                          * As a result we don't read the actual register states from
                          * the target.
                          */

                        arm11->arm.target->state = TARGET_HALTED;
                        arm_dpm_report_dscr(arm11->arm.dpm, arm11->dscr);
                }
                else
                {
                        arm11->arm.target->state = TARGET_RUNNING;
                        arm11->arm.target->debug_reason = DBG_REASON_NOTHALTED;
                }

                arm11_sc7_clear_vbw(arm11);
        }

        return ERROR_OK;
}

/**
 * Save processor state.  This is called after a HALT instruction
 * succeeds, and on other occasions the processor enters debug mode
 * (breakpoint, watchpoint, etc).  Caller has updated arm11->dscr.
 */
static int arm11_debug_entry(struct arm11_common *arm11)
{
        int retval;

        arm11->arm.target->state = TARGET_HALTED;
        arm_dpm_report_dscr(arm11->arm.dpm, arm11->dscr);

        /* REVISIT entire cache should already be invalid !!! */
        register_cache_invalidate(arm11->arm.core_cache);

        /* See e.g. ARM1136 TRM, "14.8.4 Entering Debug state" */

        /* maybe save wDTR (pending DCC write to debug SW, e.g. libdcc) */
        arm11->is_wdtr_saved = !!(arm11->dscr & DSCR_DTR_TX_FULL);
        if (arm11->is_wdtr_saved)
        {
                arm11_add_debug_SCAN_N(arm11, 0x05, ARM11_TAP_DEFAULT);

                arm11_add_IR(arm11, ARM11_INTEST, ARM11_TAP_DEFAULT);

                struct scan_field       chain5_fields[3];

                arm11_setup_field(arm11, 32, NULL,
                                &arm11->saved_wdtr, chain5_fields + 0);
                arm11_setup_field(arm11,  1, NULL, NULL,                chain5_fields + 1);
                arm11_setup_field(arm11,  1, NULL, NULL,                chain5_fields + 2);

                arm11_add_dr_scan_vc(arm11->arm.target->tap, ARRAY_SIZE(chain5_fields), chain5_fields, TAP_DRPAUSE);

        }

        /* DSCR: set the Execute ARM instruction enable bit.
         *
         * ARM1176 spec says this is needed only for wDTR/rDTR's "ITR mode",
         * but not to issue ITRs(?).  The ARMv7 arch spec says it's required
         * for executing instructions via ITR.
         */
        arm11_write_DSCR(arm11, DSCR_ITR_EN | arm11->dscr);


        /* From the spec:
           Before executing any instruction in debug state you have to drain the write buffer.
           This ensures that no imprecise Data Aborts can return at a later point:*/

        /** \todo TODO: Test drain write buffer. */

#if 0
        while (1)
        {
                /* MRC p14,0,R0,c5,c10,0 */
                //      arm11_run_instr_no_data1(arm11, /*0xee150e1a*/0xe320f000);

                /* mcr     15, 0, r0, cr7, cr10, {4} */
                arm11_run_instr_no_data1(arm11, 0xee070f9a);

                uint32_t dscr = arm11_read_DSCR(arm11);

                LOG_DEBUG("DRAIN, DSCR %08x", dscr);

                if (dscr & ARM11_DSCR_STICKY_IMPRECISE_DATA_ABORT)
                {
                        arm11_run_instr_no_data1(arm11, 0xe320f000);

                        dscr = arm11_read_DSCR(arm11);

                        LOG_DEBUG("DRAIN, DSCR %08x (DONE)", dscr);

                        break;
                }
        }
#endif

        /* Save registers.
         *
         * NOTE:  ARM1136 TRM suggests saving just R0 here now, then
         * CPSR and PC after the rDTR stuff.  We do it all at once.
         */
        retval = arm_dpm_read_current_registers(&arm11->dpm);
        if (retval != ERROR_OK)
                LOG_ERROR("DPM REG READ -- fail %d", retval);

        retval = arm11_run_instr_data_prepare(arm11);
        if (retval != ERROR_OK)
                return retval;

        /* maybe save rDTR (pending DCC read from debug SW, e.g. libdcc) */
        arm11->is_rdtr_saved = !!(arm11->dscr & DSCR_DTR_RX_FULL);
        if (arm11->is_rdtr_saved)
        {
                /* MRC p14,0,R0,c0,c5,0 (move rDTR -> r0 (-> wDTR -> local var)) */
                retval = arm11_run_instr_data_from_core_via_r0(arm11,
                                0xEE100E15, &arm11->saved_rdtr);
                if (retval != ERROR_OK)
                        return retval;
        }

        /* REVISIT Now that we've saved core state, there's may also
         * be MMU and cache state to care about ...
         */

        if (arm11->simulate_reset_on_next_halt)
        {
                arm11->simulate_reset_on_next_halt = false;

                LOG_DEBUG("Reset c1 Control Register");

                /* Write 0 (reset value) to Control register 0 to disable MMU/Cache etc. */

                /* MCR p15,0,R0,c1,c0,0 */
                retval = arm11_run_instr_data_to_core_via_r0(arm11, 0xee010f10, 0);
                if (retval != ERROR_OK)
                        return retval;

        }

        if (arm11->arm.target->debug_reason == DBG_REASON_WATCHPOINT) {
                uint32_t wfar;

                /* MRC p15, 0, <Rd>, c6, c0, 1 ; Read WFAR */
                retval = arm11_run_instr_data_from_core_via_r0(arm11,
                                ARMV4_5_MRC(15, 0, 0, 6, 0, 1),
                                &wfar);
                if (retval != ERROR_OK)
                        return retval;
                arm_dpm_report_wfar(arm11->arm.dpm, wfar);
        }


        retval = arm11_run_instr_data_finish(arm11);
        if (retval != ERROR_OK)
                return retval;

        return ERROR_OK;
}

/**
 * Restore processor state.  This is called in preparation for
 * the RESTART function.
 */
static int arm11_leave_debug_state(struct arm11_common *arm11, bool bpwp)
{
        int retval;

        /* See e.g. ARM1136 TRM, "14.8.5 Leaving Debug state" */

        /* NOTE:  the ARM1136 TRM suggests restoring all registers
         * except R0/PC/CPSR right now.  Instead, we do them all
         * at once, just a bit later on.
         */

        /* REVISIT once we start caring about MMU and cache state,
         * address it here ...
         */

        /* spec says clear wDTR and rDTR; we assume they are clear as
           otherwise our programming would be sloppy */
        {
                CHECK_RETVAL(arm11_read_DSCR(arm11));

                if (arm11->dscr & (DSCR_DTR_RX_FULL | DSCR_DTR_TX_FULL))
                {
                        /*
                        The wDTR/rDTR two registers that are used to send/receive data to/from
                        the core in tandem with corresponding instruction codes that are
                        written into the core. The RDTR FULL/WDTR FULL flag indicates that the
                        registers hold data that was written by one side (CPU or JTAG) and not
                        read out by the other side.
                        */
                        LOG_ERROR("wDTR/rDTR inconsistent (DSCR %08x)",
                                        (unsigned) arm11->dscr);
                        return ERROR_FAIL;
                }
        }

        /* maybe restore original wDTR */
        if (arm11->is_wdtr_saved)
        {
                retval = arm11_run_instr_data_prepare(arm11);
                if (retval != ERROR_OK)
                        return retval;

                /* MCR p14,0,R0,c0,c5,0 */
                retval = arm11_run_instr_data_to_core_via_r0(arm11,
                                0xee000e15, arm11->saved_wdtr);
                if (retval != ERROR_OK)
                        return retval;

                retval = arm11_run_instr_data_finish(arm11);
                if (retval != ERROR_OK)
                        return retval;
        }

        /* restore CPSR, PC, and R0 ... after flushing any modified
         * registers.
         */
        retval = arm_dpm_write_dirty_registers(&arm11->dpm, bpwp);

        retval = arm11_bpwp_flush(arm11);

        register_cache_invalidate(arm11->arm.core_cache);

        /* restore DSCR */
        arm11_write_DSCR(arm11, arm11->dscr);

        /* maybe restore rDTR */
        if (arm11->is_rdtr_saved)
        {
                arm11_add_debug_SCAN_N(arm11, 0x05, ARM11_TAP_DEFAULT);

                arm11_add_IR(arm11, ARM11_EXTEST, ARM11_TAP_DEFAULT);

                struct scan_field       chain5_fields[3];

                uint8_t                 Ready           = 0;    /* ignored */
                uint8_t                 Valid           = 0;    /* ignored */

                arm11_setup_field(arm11, 32, &arm11->saved_rdtr,
                                NULL, chain5_fields + 0);
                arm11_setup_field(arm11,  1, &Ready,    NULL, chain5_fields + 1);
                arm11_setup_field(arm11,  1, &Valid,    NULL, chain5_fields + 2);

                arm11_add_dr_scan_vc(arm11->arm.target->tap, ARRAY_SIZE(chain5_fields), chain5_fields, TAP_DRPAUSE);
        }

        /* now processor is ready to RESTART */

        return ERROR_OK;
}

/* poll current target status */
static int arm11_poll(struct target *target)
{
        int retval;
        struct arm11_common *arm11 = target_to_arm11(target);

        CHECK_RETVAL(arm11_check_init(arm11));

        if (arm11->dscr & DSCR_CORE_HALTED)
        {
                if (target->state != TARGET_HALTED)
                {
                        enum target_state old_state = target->state;

                        LOG_DEBUG("enter TARGET_HALTED");
                        retval = arm11_debug_entry(arm11);
                        if (retval != ERROR_OK)
                                return retval;

                        target_call_event_callbacks(target,
                                (old_state == TARGET_DEBUG_RUNNING)
                                        ? TARGET_EVENT_DEBUG_HALTED
                                        : TARGET_EVENT_HALTED);
                }
        }
        else
        {
                if (target->state != TARGET_RUNNING && target->state != TARGET_DEBUG_RUNNING)
                {
                        LOG_DEBUG("enter TARGET_RUNNING");
                        target->state                   = TARGET_RUNNING;
                        target->debug_reason    = DBG_REASON_NOTHALTED;
                }
        }

        return ERROR_OK;
}
/* architecture specific status reply */
static int arm11_arch_state(struct target *target)
{
        struct arm11_common *arm11 = target_to_arm11(target);
        int retval;

        retval = arm_arch_state(target);

        /* REVISIT also display ARM11-specific MMU and cache status ... */

        if (target->debug_reason == DBG_REASON_WATCHPOINT)
                LOG_USER("Watchpoint triggered at PC %#08x",
                                (unsigned) arm11->dpm.wp_pc);

        return retval;
}

/* target request support */
static int arm11_target_request_data(struct target *target,
                uint32_t size, uint8_t *buffer)
{
        LOG_WARNING("Not implemented: %s", __func__);

        return ERROR_FAIL;
}

/* target execution control */
static int arm11_halt(struct target *target)
{
        struct arm11_common *arm11 = target_to_arm11(target);

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

        if (target->state == TARGET_UNKNOWN)
        {
                arm11->simulate_reset_on_next_halt = true;
        }

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

        arm11_add_IR(arm11, ARM11_HALT, TAP_IDLE);

        CHECK_RETVAL(jtag_execute_queue());

        int i = 0;

        while (1)
        {
                CHECK_RETVAL(arm11_read_DSCR(arm11));

                if (arm11->dscr & DSCR_CORE_HALTED)
                        break;


                long long then = 0;
                if (i == 1000)
                {
                        then = timeval_ms();
                }
                if (i >= 1000)
                {
                        if ((timeval_ms()-then) > 1000)
                        {
                                LOG_WARNING("Timeout (1000ms) waiting for instructions to complete");
                                return ERROR_FAIL;
                        }
                }
                i++;
        }

        enum target_state old_state     = target->state;

        arm11_debug_entry(arm11);

        CHECK_RETVAL(
                target_call_event_callbacks(target,
                        old_state == TARGET_DEBUG_RUNNING ? TARGET_EVENT_DEBUG_HALTED : TARGET_EVENT_HALTED));

        return ERROR_OK;
}

static uint32_t
arm11_nextpc(struct arm11_common *arm11, int current, uint32_t address)
{
        void *value = arm11->arm.pc->value;

        if (!current)
                buf_set_u32(value, 0, 32, address);
        else
                address = buf_get_u32(value, 0, 32);

        return address;
}

static int arm11_resume(struct target *target, int current,
                uint32_t address, int handle_breakpoints, int debug_execution)
{
        //        LOG_DEBUG("current %d  address %08x  handle_breakpoints %d  debug_execution %d",
        //      current, address, handle_breakpoints, debug_execution);

        struct arm11_common *arm11 = target_to_arm11(target);

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


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

        address = arm11_nextpc(arm11, current, address);

        LOG_DEBUG("RESUME PC %08" PRIx32 "%s", address, !current ? "!" : "");

        /* clear breakpoints/watchpoints and VCR*/
        arm11_sc7_clear_vbw(arm11);

        if (!debug_execution)
                target_free_all_working_areas(target);

        /* Should we skip over breakpoints matching the PC? */
        if (handle_breakpoints) {
                struct breakpoint *bp;

                for (bp = target->breakpoints; bp; bp = bp->next)
                {
                        if (bp->address == address)
                        {
                                LOG_DEBUG("must step over %08" PRIx32 "", bp->address);
                                arm11_step(target, 1, 0, 0);
                                break;
                        }
                }
        }

        /* activate all breakpoints */
        if (true) {
                struct breakpoint *bp;
                unsigned brp_num = 0;

                for (bp = target->breakpoints; bp; bp = bp->next)
                {
                        struct arm11_sc7_action brp[2];

                        brp[0].write    = 1;
                        brp[0].address  = ARM11_SC7_BVR0 + brp_num;
                        brp[0].value    = bp->address;
                        brp[1].write    = 1;
                        brp[1].address  = ARM11_SC7_BCR0 + brp_num;
                        brp[1].value    = 0x1 | (3 << 1) | (0x0F << 5) | (0 << 14) | (0 << 16) | (0 << 20) | (0 << 21);

                        arm11_sc7_run(arm11, brp, ARRAY_SIZE(brp));

                        LOG_DEBUG("Add BP %d at %08" PRIx32, brp_num,
                                        bp->address);

                        brp_num++;
                }

                if (arm11->vcr)
                        arm11_sc7_set_vcr(arm11, arm11->vcr);
        }

        /* activate all watchpoints and breakpoints */
        arm11_leave_debug_state(arm11, true);

        arm11_add_IR(arm11, ARM11_RESTART, TAP_IDLE);

        CHECK_RETVAL(jtag_execute_queue());

        int i = 0;
        while (1)
        {
                CHECK_RETVAL(arm11_read_DSCR(arm11));

                LOG_DEBUG("DSCR %08x", (unsigned) arm11->dscr);

                if (arm11->dscr & DSCR_CORE_RESTARTED)
                        break;


                long long then = 0;
                if (i == 1000)
                {
                        then = timeval_ms();
                }
                if (i >= 1000)
                {
                        if ((timeval_ms()-then) > 1000)
                        {
                                LOG_WARNING("Timeout (1000ms) waiting for instructions to complete");
                                return ERROR_FAIL;
                        }
                }
                i++;
        }

        target->debug_reason = DBG_REASON_NOTHALTED;
        if (!debug_execution)
                target->state = TARGET_RUNNING;
        else
                target->state = TARGET_DEBUG_RUNNING;
        CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_RESUMED));

        return ERROR_OK;
}

static int arm11_step(struct target *target, int current,
                uint32_t address, int handle_breakpoints)
{
        LOG_DEBUG("target->state: %s",
                target_state_name(target));

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

        struct arm11_common *arm11 = target_to_arm11(target);

        address = arm11_nextpc(arm11, current, address);

        LOG_DEBUG("STEP PC %08" PRIx32 "%s", address, !current ? "!" : "");


        /** \todo TODO: Thumb not supported here */

        uint32_t        next_instruction;

        CHECK_RETVAL(arm11_read_memory_word(arm11, address, &next_instruction));

        /* skip over BKPT */
        if ((next_instruction & 0xFFF00070) == 0xe1200070)
        {
                address = arm11_nextpc(arm11, 0, address + 4);
                LOG_DEBUG("Skipping BKPT");
        }
        /* skip over Wait for interrupt / Standby */
        /* mcr  15, 0, r?, cr7, cr0, {4} */
        else if ((next_instruction & 0xFFFF0FFF) == 0xee070f90)
        {
                address = arm11_nextpc(arm11, 0, address + 4);
                LOG_DEBUG("Skipping WFI");
        }
        /* ignore B to self */
        else if ((next_instruction & 0xFEFFFFFF) == 0xeafffffe)
        {
                LOG_DEBUG("Not stepping jump to self");
        }
        else
        {
                /** \todo TODO: check if break-/watchpoints make any sense at all in combination
                * with this. */

                /** \todo TODO: check if disabling IRQs might be a good idea here. Alternatively
                * the VCR might be something worth looking into. */


                /* Set up breakpoint for stepping */

                struct arm11_sc7_action brp[2];

                brp[0].write    = 1;
                brp[0].address  = ARM11_SC7_BVR0;
                brp[1].write    = 1;
                brp[1].address  = ARM11_SC7_BCR0;

                if (arm11->hardware_step)
                {
                        /* Hardware single stepping ("instruction address
                         * mismatch") is used if enabled.  It's not quite
                         * exactly "run one instruction"; "branch to here"
                         * loops won't break, neither will some other cases,
                         * but it's probably the best default.
                         *
                         * Hardware single stepping isn't supported on v6
                         * debug modules.  ARM1176 and v7 can support it...
                         *
                         * FIXME Thumb stepping likely needs to use 0x03
                         * or 0xc0 byte masks, not 0x0f.
                         */
                         brp[0].value   = address;
                         brp[1].value   = 0x1 | (3 << 1) | (0x0F << 5)
                                        | (0 << 14) | (0 << 16) | (0 << 20)
                                        | (2 << 21);
                } else
                {
                        /* Sets a breakpoint on the next PC, as calculated
                         * by instruction set simulation.
                         *
                         * REVISIT stepping Thumb on ARM1156 requires Thumb2
                         * support from the simulator.
                         */
                        uint32_t next_pc;
                        int retval;

                        retval = arm_simulate_step(target, &next_pc);
                        if (retval != ERROR_OK)
                                return retval;

                        brp[0].value    = next_pc;
                        brp[1].value    = 0x1 | (3 << 1) | (0x0F << 5)
                                        | (0 << 14) | (0 << 16) | (0 << 20)
                                        | (0 << 21);
                }

                CHECK_RETVAL(arm11_sc7_run(arm11, brp, ARRAY_SIZE(brp)));

                /* resume */


                if (arm11->step_irq_enable)
                        /* this disable should be redundant ... */
                        arm11->dscr &= ~DSCR_INT_DIS;
                else
                        arm11->dscr |= DSCR_INT_DIS;


                CHECK_RETVAL(arm11_leave_debug_state(arm11, handle_breakpoints));

                arm11_add_IR(arm11, ARM11_RESTART, TAP_IDLE);

                CHECK_RETVAL(jtag_execute_queue());

                /* wait for halt */
                int i = 0;

                while (1)
                {
                        const uint32_t mask = DSCR_CORE_RESTARTED
                                        | DSCR_CORE_HALTED;

                        CHECK_RETVAL(arm11_read_DSCR(arm11));
                        LOG_DEBUG("DSCR %08x e", (unsigned) arm11->dscr);

                        if ((arm11->dscr & mask) == mask)
                                break;

                        long long then = 0;
                        if (i == 1000)
                        {
                                then = timeval_ms();
                        }
                        if (i >= 1000)
                        {
                                if ((timeval_ms()-then) > 1000)
                                {
                                        LOG_WARNING("Timeout (1000ms) waiting for instructions to complete");
                                        return ERROR_FAIL;
                                }
                        }
                        i++;
                }

                /* clear breakpoint */
                arm11_sc7_clear_vbw(arm11);

                /* save state */
                CHECK_RETVAL(arm11_debug_entry(arm11));

                /* restore default state */
                arm11->dscr &= ~DSCR_INT_DIS;

        }

        target->debug_reason = DBG_REASON_SINGLESTEP;

        CHECK_RETVAL(target_call_event_callbacks(target, TARGET_EVENT_HALTED));

        return ERROR_OK;
}

static int arm11_assert_reset(struct target *target)
{
        struct arm11_common *arm11 = target_to_arm11(target);

        /* optionally catch reset vector */
        if (target->reset_halt && !(arm11->vcr & 1))
                arm11_sc7_set_vcr(arm11, arm11->vcr | 1);

        /* Issue some kind of warm reset. */
        if (target_has_event_action(target, TARGET_EVENT_RESET_ASSERT)) {
                target_handle_event(target, TARGET_EVENT_RESET_ASSERT);
        } else if (jtag_get_reset_config() & RESET_HAS_SRST) {
                /* REVISIT handle "pulls" cases, if there's
                 * hardware that needs them to work.
                 */
                jtag_add_reset(0, 1);
        } else {
                LOG_ERROR("%s: how to reset?", target_name(target));
                return ERROR_FAIL;
        }

        /* registers are now invalid */
        register_cache_invalidate(arm11->arm.core_cache);

        target->state = TARGET_RESET;

        return ERROR_OK;
}

/*
 * - There is another bug in the arm11 core.  (iMX31 specific again?)
 *   When you generate an access to external logic (for example DDR
 *   controller via AHB bus) and that block is not configured (perhaps
 *   it is still held in reset), that transaction will never complete.
 *   This will hang arm11 core but it will also hang JTAG controller.
 *   Nothing short of srst assertion will bring it out of this.
 */

static int arm11_deassert_reset(struct target *target)
{
        struct arm11_common *arm11 = target_to_arm11(target);
        int retval;

        /* be certain SRST is off */
        jtag_add_reset(0, 0);

        /* WORKAROUND i.MX31 problems:  SRST goofs the TAP, and resets
         * at least DSCR.  OMAP24xx doesn't show that problem, though
         * SRST-only reset seems to be problematic for other reasons.
         * (Secure boot sequences being one likelihood!)
         */
        jtag_add_tlr();

        retval = arm11_poll(target);

        if (target->reset_halt) {
                if (target->state != TARGET_HALTED) {
                        LOG_WARNING("%s: ran after reset and before halt ...",
                                        target_name(target));
                        if ((retval = target_halt(target)) != ERROR_OK)
                                return retval;
                }
        }

        /* maybe restore vector catch config */
        if (target->reset_halt && !(arm11->vcr & 1))
                arm11_sc7_set_vcr(arm11, arm11->vcr);

        return ERROR_OK;
}

static int arm11_soft_reset_halt(struct target *target)
{
        LOG_WARNING("Not implemented: %s", __func__);

        return ERROR_FAIL;
}

/* target memory access
 * size: 1 = byte (8bit), 2 = half-word (16bit), 4 = word (32bit)
 * count: number of items of <size>
 *
 * arm11_config_memrw_no_increment - in the future we may want to be able
 * to read/write a range of data to a "port". a "port" is an action on
 * read memory address for some peripheral.
 */
static int arm11_read_memory_inner(struct target *target,
                uint32_t address, uint32_t size, uint32_t count, uint8_t *buffer,
                bool arm11_config_memrw_no_increment)
{
        /** \todo TODO: check if buffer cast to uint32_t* and uint16_t* might cause alignment problems */
        int retval;

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

        LOG_DEBUG("ADDR %08" PRIx32 "  SIZE %08" PRIx32 "  COUNT %08" PRIx32 "", address, size, count);

        struct arm11_common *arm11 = target_to_arm11(target);

        retval = arm11_run_instr_data_prepare(arm11);
        if (retval != ERROR_OK)
                return retval;

        /* MRC p14,0,r0,c0,c5,0 */
        retval = arm11_run_instr_data_to_core1(arm11, 0xee100e15, address);
        if (retval != ERROR_OK)
                return retval;

        switch (size)
        {
        case 1:
                arm11->arm.core_cache->reg_list[1].dirty = true;

                for (size_t i = 0; i < count; i++)
                {
                        /* ldrb    r1, [r0], #1 */
                        /* ldrb    r1, [r0] */
                        arm11_run_instr_no_data1(arm11,
                                        !arm11_config_memrw_no_increment ? 0xe4d01001 : 0xe5d01000);

                        uint32_t res;
                        /* MCR p14,0,R1,c0,c5,0 */
                        arm11_run_instr_data_from_core(arm11, 0xEE001E15, &res, 1);

                        *buffer++ = res;
                }

                break;

        case 2:
                {
                        arm11->arm.core_cache->reg_list[1].dirty = true;

                        for (size_t i = 0; i < count; i++)
                        {
                                /* ldrh    r1, [r0], #2 */
                                arm11_run_instr_no_data1(arm11,
                                        !arm11_config_memrw_no_increment ? 0xe0d010b2 : 0xe1d010b0);

                                uint32_t res;

                                /* MCR p14,0,R1,c0,c5,0 */
                                arm11_run_instr_data_from_core(arm11, 0xEE001E15, &res, 1);

                                uint16_t svalue = res;
                                memcpy(buffer + i * sizeof(uint16_t), &svalue, sizeof(uint16_t));
                        }

                        break;
                }

        case 4:
                {
                uint32_t instr = !arm11_config_memrw_no_increment ? 0xecb05e01 : 0xed905e00;
                /** \todo TODO: buffer cast to uint32_t* causes alignment warnings */
                uint32_t *words = (uint32_t *)buffer;

                /* LDC p14,c5,[R0],#4 */
                /* LDC p14,c5,[R0] */
                arm11_run_instr_data_from_core(arm11, instr, words, count);
                break;
                }
        }

        return arm11_run_instr_data_finish(arm11);
}

static int arm11_read_memory(struct target *target, uint32_t address, uint32_t size, uint32_t count, uint8_t *buffer)
{
        return arm11_read_memory_inner(target, address, size, count, buffer, false);
}

/*
* no_increment - in the future we may want to be able
* to read/write a range of data to a "port". a "port" is an action on
* read memory address for some peripheral.
*/
static int arm11_write_memory_inner(struct target *target,
                uint32_t address, uint32_t size,
                uint32_t count, uint8_t *buffer,
                bool no_increment)
{
        int retval;

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

        LOG_DEBUG("ADDR %08" PRIx32 "  SIZE %08" PRIx32 "  COUNT %08" PRIx32 "", address, size, count);

        struct arm11_common *arm11 = target_to_arm11(target);

        retval = arm11_run_instr_data_prepare(arm11);
        if (retval != ERROR_OK)
                return retval;

        /* load r0 with buffer address */
        /* MRC p14,0,r0,c0,c5,0 */
        retval = arm11_run_instr_data_to_core1(arm11, 0xee100e15, address);
        if (retval != ERROR_OK)
                return retval;

        /* burst writes are not used for single words as those may well be
         * reset init script writes.
         *
         * The other advantage is that as burst writes are default, we'll
         * now exercise both burst and non-burst code paths with the
         * default settings, increasing code coverage.
         */
        bool burst = arm11->memwrite_burst && (count > 1);

        switch (size)
        {
        case 1:
                {
                        arm11->arm.core_cache->reg_list[1].dirty = true;

                        for (size_t i = 0; i < count; i++)
                        {
                                /* load r1 from DCC with byte data */
                                /* MRC p14,0,r1,c0,c5,0 */
                                retval = arm11_run_instr_data_to_core1(arm11, 0xee101e15, *buffer++);
                                if (retval != ERROR_OK)
                                        return retval;

                                /* write r1 to memory */
                                /* strb    r1, [r0], #1 */
                                /* strb    r1, [r0] */
                                retval = arm11_run_instr_no_data1(arm11,
                                        !no_increment
                                                ? 0xe4c01001
                                                : 0xe5c01000);
                                if (retval != ERROR_OK)
                                        return retval;
                        }

                        break;
                }

        case 2:
                {
                        arm11->arm.core_cache->reg_list[1].dirty = true;

                        for (size_t i = 0; i < count; i++)
                        {
                                uint16_t value;
                                memcpy(&value, buffer + i * sizeof(uint16_t), sizeof(uint16_t));

                                /* load r1 from DCC with halfword data */
                                /* MRC p14,0,r1,c0,c5,0 */
                                retval = arm11_run_instr_data_to_core1(arm11, 0xee101e15, value);
                                if (retval != ERROR_OK)
                                        return retval;

                                /* write r1 to memory */
                                /* strh    r1, [r0], #2 */
                                /* strh    r1, [r0] */
                                retval = arm11_run_instr_no_data1(arm11,
                                        !no_increment
                                                ? 0xe0c010b2
                                                : 0xe1c010b0);
                                if (retval != ERROR_OK)
                                        return retval;
                        }

                        break;
                }

        case 4: {
                /* stream word data through DCC directly to memory */
                /* increment:           STC p14,c5,[R0],#4 */
                /* no increment:        STC p14,c5,[R0]*/
                uint32_t instr = !no_increment ? 0xeca05e01 : 0xed805e00;

                /** \todo TODO: buffer cast to uint32_t* causes alignment warnings */
                uint32_t *words = (uint32_t*)buffer;

                /* "burst" here just means trusting each instruction executes
                 * fully before we run the next one:  per-word roundtrips, to
                 * check the Ready flag, are not used.
                 */
                if (!burst)
                        retval = arm11_run_instr_data_to_core(arm11,
                                        instr, words, count);
                else
                        retval = arm11_run_instr_data_to_core_noack(arm11,
                                        instr, words, count);
                if (retval != ERROR_OK)
                        return retval;

                break;
        }
        }

        /* r0 verification */
        if (!no_increment)
        {
                uint32_t r0;

                /* MCR p14,0,R0,c0,c5,0 */
                retval = arm11_run_instr_data_from_core(arm11, 0xEE000E15, &r0, 1);
                if (retval != ERROR_OK)
                        return retval;

                if (address + size * count != r0)
                {
                        LOG_ERROR("Data transfer failed. Expected end "
                                        "address 0x%08x, got 0x%08x",
                                        (unsigned) (address + size * count),
                                        (unsigned) r0);

                        if (burst)
                                LOG_ERROR("use 'arm11 memwrite burst disable' to disable fast burst mode");

                        if (arm11->memwrite_error_fatal)
                                return ERROR_FAIL;
                }
        }

        return arm11_run_instr_data_finish(arm11);
}

static int arm11_write_memory(struct target *target,
                uint32_t address, uint32_t size,
                uint32_t count, uint8_t *buffer)
{
        /* pointer increment matters only for multi-unit writes ...
         * not e.g. to a "reset the chip" controller.
         */
        return arm11_write_memory_inner(target, address, size,
                        count, buffer, count == 1);
}

/* write target memory in multiples of 4 byte, optimized for writing large quantities of data */
static int arm11_bulk_write_memory(struct target *target,
                uint32_t address, uint32_t count, uint8_t *buffer)
{
        if (target->state != TARGET_HALTED)
        {
                LOG_WARNING("target was not halted");
                return ERROR_TARGET_NOT_HALTED;
        }

        return arm11_write_memory(target, address, 4, count, buffer);
}

/* target break-/watchpoint control
* rw: 0 = write, 1 = read, 2 = access
*/
static int arm11_add_breakpoint(struct target *target,
                struct breakpoint *breakpoint)
{
        struct arm11_common *arm11 = target_to_arm11(target);

#if 0
        if (breakpoint->type == BKPT_SOFT)
        {
                LOG_INFO("sw breakpoint requested, but software breakpoints not enabled");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }
#endif

        if (!arm11->free_brps)
        {
                LOG_DEBUG("no breakpoint unit available for hardware breakpoint");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }

        if (breakpoint->length != 4)
        {
                LOG_DEBUG("only breakpoints of four bytes length supported");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }

        arm11->free_brps--;

        return ERROR_OK;
}

static int arm11_remove_breakpoint(struct target *target,
                struct breakpoint *breakpoint)
{
        struct arm11_common *arm11 = target_to_arm11(target);

        arm11->free_brps++;

        return ERROR_OK;
}

static int arm11_target_create(struct target *target, Jim_Interp *interp)
{
        struct arm11_common *arm11;

        if (target->tap == NULL)
                return ERROR_FAIL;

        if (target->tap->ir_length != 5)
        {
                LOG_ERROR("'target arm11' expects IR LENGTH = 5");
                return ERROR_COMMAND_SYNTAX_ERROR;
        }

        arm11 = calloc(1, sizeof *arm11);
        if (!arm11)
                return ERROR_FAIL;

        arm_init_arch_info(target, &arm11->arm);

        arm11->jtag_info.tap = target->tap;
        arm11->jtag_info.scann_size = 5;
        arm11->jtag_info.scann_instr = ARM11_SCAN_N;
        arm11->jtag_info.cur_scan_chain = ~0;   /* invalid/unknown */
        arm11->jtag_info.intest_instr = ARM11_INTEST;

        arm11->memwrite_burst = true;
        arm11->memwrite_error_fatal = true;

        return ERROR_OK;
}

static int arm11_init_target(struct command_context *cmd_ctx,
                struct target *target)
{
        /* Initialize anything we can set up without talking to the target */
        return ERROR_OK;
}

/* talk to the target and set things up */
static int arm11_examine(struct target *target)
{
        int retval;
        char *type;
        struct arm11_common *arm11 = target_to_arm11(target);
        uint32_t didr, device_id;
        uint8_t implementor;

        /* FIXME split into do-first-time and do-every-time logic ... */

        /* check IDCODE */

        arm11_add_IR(arm11, ARM11_IDCODE, ARM11_TAP_DEFAULT);

        struct scan_field               idcode_field;

        arm11_setup_field(arm11, 32, NULL, &device_id, &idcode_field);

        arm11_add_dr_scan_vc(arm11->arm.target->tap, 1, &idcode_field, TAP_DRPAUSE);

        /* check DIDR */

        arm11_add_debug_SCAN_N(arm11, 0x00, ARM11_TAP_DEFAULT);

        arm11_add_IR(arm11, ARM11_INTEST, ARM11_TAP_DEFAULT);

        struct scan_field               chain0_fields[2];

        arm11_setup_field(arm11, 32, NULL, &didr, chain0_fields + 0);
        arm11_setup_field(arm11,  8, NULL, &implementor, chain0_fields + 1);

        arm11_add_dr_scan_vc(arm11->arm.target->tap, ARRAY_SIZE(chain0_fields), chain0_fields, TAP_IDLE);

        CHECK_RETVAL(jtag_execute_queue());

        /* assume the manufacturer id is ok; check the part # */
        switch ((device_id >> 12) & 0xFFFF)
        {
        case 0x7B36:
                type = "ARM1136";
                break;
        case 0x7B37:
                type = "ARM11 MPCore";
                break;
        case 0x7B56:
                type = "ARM1156";
                break;
        case 0x7B76:
                arm11->arm.core_type = ARM_MODE_MON;
                /* NOTE: could default arm11->hardware_step to true */
                type = "ARM1176";
                break;
        default:
                LOG_ERROR("unexpected ARM11 ID code");
                return ERROR_FAIL;
        }
        LOG_INFO("found %s", type);

        /* unlikely this could ever fail, but ... */
        switch ((didr >> 16) & 0x0F) {
        case ARM11_DEBUG_V6:
        case ARM11_DEBUG_V61:           /* supports security extensions */
                break;
        default:
                LOG_ERROR("Only ARM v6 and v6.1 debug supported.");
                return ERROR_FAIL;
        }

        arm11->brp = ((didr >> 24) & 0x0F) + 1;

        /** \todo TODO: reserve one brp slot if we allow breakpoints during step */
        arm11->free_brps = arm11->brp;

        LOG_DEBUG("IDCODE %08" PRIx32 " IMPLEMENTOR %02x DIDR %08" PRIx32,
                        device_id, implementor, didr);

        /* as a side-effect this reads DSCR and thus
         * clears the ARM11_DSCR_STICKY_PRECISE_DATA_ABORT / Sticky Precise Data Abort Flag
         * as suggested by the spec.
         */

        retval = arm11_check_init(arm11);
        if (retval != ERROR_OK)
                return retval;

        /* Build register cache "late", after target_init(), since we
         * want to know if this core supports Secure Monitor mode.
         */
        if (!target_was_examined(target))
                retval = arm11_dpm_init(arm11, didr);

        /* ETM on ARM11 still uses original scanchain 6 access mode */
        if (arm11->arm.etm && !target_was_examined(target)) {
                *register_get_last_cache_p(&target->reg_cache) =
                        etm_build_reg_cache(target, &arm11->jtag_info,
                                        arm11->arm.etm);
                retval = etm_setup(target);
        }

        target_set_examined(target);

        return ERROR_OK;
}


#define ARM11_BOOL_WRAPPER(name, print_name)    \
        COMMAND_HANDLER(arm11_handle_bool_##name) \
        { \
                struct target *target = get_current_target(CMD_CTX); \
                struct arm11_common *arm11 = target_to_arm11(target); \
                \
                return CALL_COMMAND_HANDLER(handle_command_parse_bool, \
                                &arm11->name, print_name); \
        }

ARM11_BOOL_WRAPPER(memwrite_burst, "memory write burst mode")
ARM11_BOOL_WRAPPER(memwrite_error_fatal, "fatal error mode for memory writes")
ARM11_BOOL_WRAPPER(step_irq_enable, "IRQs while stepping")
ARM11_BOOL_WRAPPER(hardware_step, "hardware single step")

/* REVISIT handle the VCR bits like other ARMs:  use symbols for
 * input and output values.
 */

COMMAND_HANDLER(arm11_handle_vcr)
{
        struct target *target = get_current_target(CMD_CTX);
        struct arm11_common *arm11 = target_to_arm11(target);

        switch (CMD_ARGC) {
        case 0:
                break;
        case 1:
                COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], arm11->vcr);
                break;
        default:
                return ERROR_COMMAND_SYNTAX_ERROR;
        }

        LOG_INFO("VCR 0x%08" PRIx32 "", arm11->vcr);
        return ERROR_OK;
}

static const struct command_registration arm11_mw_command_handlers[] = {
        {
                .name = "burst",
                .handler = arm11_handle_bool_memwrite_burst,
                .mode = COMMAND_ANY,
                .help = "Display or modify flag controlling potentially "
                        "risky fast burst mode (default: enabled)",
                .usage = "['enable'|'disable']",
        },
        {
                .name = "error_fatal",
                .handler = arm11_handle_bool_memwrite_error_fatal,
                .mode = COMMAND_ANY,
                .help = "Display or modify flag controlling transfer "
                        "termination on transfer errors"
                        " (default: enabled)",
                .usage = "['enable'|'disable']",
        },
        COMMAND_REGISTRATION_DONE
};
static const struct command_registration arm11_any_command_handlers[] = {
        {
                /* "hardware_step" is only here to check if the default
                 * simulate + breakpoint implementation is broken.
                 * TEMPORARY! NOT DOCUMENTED! */
                .name = "hardware_step",
                .handler = arm11_handle_bool_hardware_step,
                .mode = COMMAND_ANY,
                .help = "DEBUG ONLY - Hardware single stepping"
                        " (default: disabled)",
                .usage = "['enable'|'disable']",
        },
        {
                .name = "memwrite",
                .mode = COMMAND_ANY,
                .help = "memwrite command group",
                .chain = arm11_mw_command_handlers,
        },
        {
                .name = "step_irq_enable",
                .handler = arm11_handle_bool_step_irq_enable,
                .mode = COMMAND_ANY,
                .help = "Display or modify flag controlling interrupt "
                        "enable while stepping (default: disabled)",
                .usage = "['enable'|'disable']",
        },
        {
                .name = "vcr",
                .handler = arm11_handle_vcr,
                .mode = COMMAND_ANY,
                .help = "Display or modify Vector Catch Register",
                .usage = "[value]",
        },
        COMMAND_REGISTRATION_DONE
};

static const struct command_registration arm11_command_handlers[] = {
        {
                .chain = arm_command_handlers,
        },
        {
                .chain = etm_command_handlers,
        },
        {
                .name = "arm11",
                .mode = COMMAND_ANY,
                .help = "ARM11 command group",
                .chain = arm11_any_command_handlers,
        },
        COMMAND_REGISTRATION_DONE
};

/** Holds methods for ARM11xx targets. */
struct target_type arm11_target = {
        .name =                 "arm11",

        .poll =                 arm11_poll,
        .arch_state =           arm11_arch_state,

        .target_request_data =  arm11_target_request_data,

        .halt =                 arm11_halt,
        .resume =               arm11_resume,
        .step =                 arm11_step,

        .assert_reset =         arm11_assert_reset,
        .deassert_reset =       arm11_deassert_reset,
        .soft_reset_halt =      arm11_soft_reset_halt,

        .get_gdb_reg_list =     arm_get_gdb_reg_list,

        .read_memory =          arm11_read_memory,
        .write_memory =         arm11_write_memory,

        .bulk_write_memory =    arm11_bulk_write_memory,

        .checksum_memory =      arm_checksum_memory,
        .blank_check_memory =   arm_blank_check_memory,

        .add_breakpoint =       arm11_add_breakpoint,
        .remove_breakpoint =    arm11_remove_breakpoint,

        .run_algorithm =        armv4_5_run_algorithm,

        .commands =             arm11_command_handlers,
        .target_create =        arm11_target_create,
        .init_target =          arm11_init_target,
        .examine =              arm11_examine,
};