riscv-011.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/*
 * Support for RISC-V, debug version 0.11. This was never an officially adopted
 * spec, but SiFive made some silicon that uses it.
 */
 
#include <assert.h>
#include <stdlib.h>
#include <time.h>
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include "target/target.h"
#include "target/algorithm.h"
#include "target/target_type.h"
#include <helper/log.h>
#include "jtag/jtag.h"
#include "target/register.h"
#include "target/breakpoints.h"
#include "helper/time_support.h"
#include "riscv.h"
#include "asm.h"
#include "gdb_regs.h"
 
#define get_field(reg, mask) (((reg) & (mask)) / ((mask) & ~((mask) << 1)))
#define set_field(reg, mask, val) (((reg) & ~(mask)) | (((val) * ((mask) & ~((mask) << 1))) & (mask)))
 
/* Constants for legacy SiFive hardware breakpoints. */
#define CSR_BPCONTROL_X         (1<<0)
#define CSR_BPCONTROL_W         (1<<1)
#define CSR_BPCONTROL_R         (1<<2)
#define CSR_BPCONTROL_U         (1<<3)
#define CSR_BPCONTROL_S         (1<<4)
#define CSR_BPCONTROL_H         (1<<5)
#define CSR_BPCONTROL_M         (1<<6)
#define CSR_BPCONTROL_BPMATCH   (0xf<<7)
#define CSR_BPCONTROL_BPACTION  (0xff<<11)
 
#define DEBUG_ROM_START     0x800
#define DEBUG_ROM_RESUME    (DEBUG_ROM_START + 4)
#define DEBUG_ROM_EXCEPTION (DEBUG_ROM_START + 8)
#define DEBUG_RAM_START     0x400
 
#define SETHALTNOT              0x10c
 
/*** JTAG registers. ***/
 
#define DTMCONTROL                  0x10
#define DTMCONTROL_DBUS_RESET       (1<<16)
#define DTMCONTROL_IDLE             (7<<10)
#define DTMCONTROL_ADDRBITS         (0xf<<4)
#define DTMCONTROL_VERSION          (0xf)
 
#define DBUS                        0x11
#define DBUS_OP_START               0
#define DBUS_OP_SIZE                2
typedef enum {
    DBUS_OP_NOP = 0,
    DBUS_OP_READ = 1,
    DBUS_OP_WRITE = 2
} dbus_op_t;
typedef enum {
    DBUS_STATUS_SUCCESS = 0,
    DBUS_STATUS_FAILED = 2,
    DBUS_STATUS_BUSY = 3
} dbus_status_t;
#define DBUS_DATA_START             2
#define DBUS_DATA_SIZE              34
#define DBUS_ADDRESS_START          36
 
typedef enum {
    RE_OK,
    RE_FAIL,
    RE_AGAIN
} riscv_error_t;
 
typedef enum slot {
    SLOT0,
    SLOT1,
    SLOT_LAST,
} slot_t;
 
/*** Debug Bus registers. ***/
 
#define DMCONTROL               0x10
#define DMCONTROL_INTERRUPT     (((uint64_t)1)<<33)
#define DMCONTROL_HALTNOT       (((uint64_t)1)<<32)
#define DMCONTROL_BUSERROR      (7<<19)
#define DMCONTROL_SERIAL        (3<<16)
#define DMCONTROL_AUTOINCREMENT (1<<15)
#define DMCONTROL_ACCESS        (7<<12)
#define DMCONTROL_HARTID        (0x3ff<<2)
#define DMCONTROL_NDRESET       (1<<1)
#define DMCONTROL_FULLRESET     1
 
#define DMINFO                  0x11
#define DMINFO_ABUSSIZE         (0x7fU<<25)
#define DMINFO_SERIALCOUNT      (0xf<<21)
#define DMINFO_ACCESS128        (1<<20)
#define DMINFO_ACCESS64         (1<<19)
#define DMINFO_ACCESS32         (1<<18)
#define DMINFO_ACCESS16         (1<<17)
#define DMINFO_ACCESS8          (1<<16)
#define DMINFO_DRAMSIZE         (0x3f<<10)
#define DMINFO_AUTHENTICATED    (1<<5)
#define DMINFO_AUTHBUSY         (1<<4)
#define DMINFO_AUTHTYPE         (3<<2)
#define DMINFO_VERSION          3
 
#define DMAUTHDATA0             0x12
#define DMAUTHDATA1             0x13
 
/*** Info about the core being debugged. ***/
 
#define DBUS_ADDRESS_UNKNOWN    0xffff
 
#define DRAM_CACHE_SIZE     16
 
struct trigger {
    uint64_t address;
    uint32_t length;
    uint64_t mask;
    uint64_t value;
    bool read, write, execute;
    int unique_id;
};
 
struct memory_cache_line {
    uint32_t data;
    bool valid;
    bool dirty;
};
 
typedef struct {
    /* Number of address bits in the dbus register. */
    uint8_t addrbits;
    /* Number of words in Debug RAM. */
    unsigned int dramsize;
    uint64_t dcsr;
    uint64_t dpc;
    uint64_t tselect;
    bool tselect_dirty;
    /* The value that mstatus actually has on the target right now. This is not
     * the value we present to the user. That one may be stored in the
     * reg_cache. */
    uint64_t mstatus_actual;
 
    struct memory_cache_line dram_cache[DRAM_CACHE_SIZE];
 
    /* Number of run-test/idle cycles the target requests we do after each dbus
     * access. */
    unsigned int dtmcontrol_idle;
 
    /* This value is incremented every time a dbus access comes back as "busy".
     * It's used to determine how many run-test/idle cycles to feed the target
     * in between accesses. */
    unsigned int dbus_busy_delay;
 
    /* This value is incremented every time we read the debug interrupt as
     * high.  It's used to add extra run-test/idle cycles after setting debug
     * interrupt high, so ideally we never have to perform a whole extra scan
     * before the interrupt is cleared. */
    unsigned int interrupt_high_delay;
 
    bool never_halted;
} riscv011_info_t;
 
typedef struct {
    bool haltnot;
    bool interrupt;
} bits_t;
 
/*** Necessary prototypes. ***/
 
static int poll_target(struct target *target, bool announce);
static int riscv011_poll(struct target *target);
static int get_register(struct target *target, riscv_reg_t *value, int regid);
 
/*** Utility functions. ***/
 
#define DEBUG_LENGTH    264
 
static riscv011_info_t *get_info(const struct target *target)
{
    struct riscv_info *info = target->arch_info;
    assert(info);
    assert(info->version_specific);
    return info->version_specific;
}
 
static unsigned int slot_offset(const struct target *target, slot_t slot)
{
    riscv011_info_t *info = get_info(target);
    switch (riscv_xlen(target)) {
        case 32:
            switch (slot) {
                case SLOT0: return 4;
                case SLOT1: return 5;
                case SLOT_LAST: return info->dramsize-1;
            }
            break;
        case 64:
            switch (slot) {
                case SLOT0: return 4;
                case SLOT1: return 6;
                case SLOT_LAST: return info->dramsize-2;
            }
    }
    LOG_ERROR("slot_offset called with xlen=%d, slot=%d",
            riscv_xlen(target), slot);
    assert(0);
    return 0; /* Silence -Werror=return-type */
}
 
static uint32_t load_slot(const struct target *target, unsigned int dest,
        slot_t slot)
{
    unsigned int offset = DEBUG_RAM_START + 4 * slot_offset(target, slot);
    return load(target, dest, ZERO, offset);
}
 
static uint32_t store_slot(const struct target *target, unsigned int src,
        slot_t slot)
{
    unsigned int offset = DEBUG_RAM_START + 4 * slot_offset(target, slot);
    return store(target, src, ZERO, offset);
}
 
static uint16_t dram_address(unsigned int index)
{
    if (index < 0x10)
        return index;
    else
        return 0x40 + index - 0x10;
}
 
static uint32_t dtmcontrol_scan(struct target *target, uint32_t out)
{
    struct scan_field field;
    uint8_t in_value[4];
    uint8_t out_value[4] = { 0 };
 
    buf_set_u32(out_value, 0, 32, out);
 
    jtag_add_ir_scan(target->tap, &select_dtmcontrol, TAP_IDLE);
 
    field.num_bits = 32;
    field.out_value = out_value;
    field.in_value = in_value;
    jtag_add_dr_scan(target->tap, 1, &field, TAP_IDLE);
 
    /* Always return to dbus. */
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    int retval = jtag_execute_queue();
    if (retval != ERROR_OK) {
        LOG_ERROR("failed jtag scan: %d", retval);
        return retval;
    }
 
    uint32_t in = buf_get_u32(field.in_value, 0, 32);
    LOG_DEBUG("DTMCONTROL: 0x%x -> 0x%x", out, in);
 
    return in;
}
 
static uint32_t idcode_scan(struct target *target)
{
    struct scan_field field;
    uint8_t in_value[4];
 
    jtag_add_ir_scan(target->tap, &select_idcode, TAP_IDLE);
 
    field.num_bits = 32;
    field.out_value = NULL;
    field.in_value = in_value;
    jtag_add_dr_scan(target->tap, 1, &field, TAP_IDLE);
 
    int retval = jtag_execute_queue();
    if (retval != ERROR_OK) {
        LOG_ERROR("failed jtag scan: %d", retval);
        return retval;
    }
 
    /* Always return to dbus. */
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    uint32_t in = buf_get_u32(field.in_value, 0, 32);
    LOG_DEBUG("IDCODE: 0x0 -> 0x%x", in);
 
    return in;
}
 
static void increase_dbus_busy_delay(struct target *target)
{
    riscv011_info_t *info = get_info(target);
    info->dbus_busy_delay += info->dbus_busy_delay / 10 + 1;
    LOG_DEBUG("dtmcontrol_idle=%d, dbus_busy_delay=%d, interrupt_high_delay=%d",
            info->dtmcontrol_idle, info->dbus_busy_delay,
            info->interrupt_high_delay);
 
    dtmcontrol_scan(target, DTMCONTROL_DBUS_RESET);
}
 
static void increase_interrupt_high_delay(struct target *target)
{
    riscv011_info_t *info = get_info(target);
    info->interrupt_high_delay += info->interrupt_high_delay / 10 + 1;
    LOG_DEBUG("dtmcontrol_idle=%d, dbus_busy_delay=%d, interrupt_high_delay=%d",
            info->dtmcontrol_idle, info->dbus_busy_delay,
            info->interrupt_high_delay);
}
 
static void add_dbus_scan(const struct target *target, struct scan_field *field,
        uint8_t *out_value, uint8_t *in_value, dbus_op_t op,
        uint16_t address, uint64_t data)
{
    riscv011_info_t *info = get_info(target);
    RISCV_INFO(r);
 
    if (r->reset_delays_wait >= 0) {
        r->reset_delays_wait--;
        if (r->reset_delays_wait < 0) {
            info->dbus_busy_delay = 0;
            info->interrupt_high_delay = 0;
        }
    }
 
    field->num_bits = info->addrbits + DBUS_OP_SIZE + DBUS_DATA_SIZE;
    field->in_value = in_value;
    field->out_value = out_value;
 
    buf_set_u64(out_value, DBUS_OP_START, DBUS_OP_SIZE, op);
    buf_set_u64(out_value, DBUS_DATA_START, DBUS_DATA_SIZE, data);
    buf_set_u64(out_value, DBUS_ADDRESS_START, info->addrbits, address);
 
    jtag_add_dr_scan(target->tap, 1, field, TAP_IDLE);
 
    int idle_count = info->dtmcontrol_idle + info->dbus_busy_delay;
    if (data & DMCONTROL_INTERRUPT)
        idle_count += info->interrupt_high_delay;
 
    if (idle_count)
        jtag_add_runtest(idle_count, TAP_IDLE);
}
 
static void dump_field(const struct scan_field *field)
{
    static const char * const op_string[] = {"nop", "r", "w", "?"};
    static const char * const status_string[] = {"+", "?", "F", "b"};
 
    if (debug_level < LOG_LVL_DEBUG)
        return;
 
    uint64_t out = buf_get_u64(field->out_value, 0, field->num_bits);
    unsigned int out_op = (out >> DBUS_OP_START) & ((1 << DBUS_OP_SIZE) - 1);
    char out_interrupt = ((out >> DBUS_DATA_START) & DMCONTROL_INTERRUPT) ? 'i' : '.';
    char out_haltnot = ((out >> DBUS_DATA_START) & DMCONTROL_HALTNOT) ? 'h' : '.';
    unsigned int out_data = out >> 2;
    unsigned int out_address = out >> DBUS_ADDRESS_START;
    uint64_t in = buf_get_u64(field->in_value, 0, field->num_bits);
    unsigned int in_op = (in >> DBUS_OP_START) & ((1 << DBUS_OP_SIZE) - 1);
    char in_interrupt = ((in >> DBUS_DATA_START) & DMCONTROL_INTERRUPT) ? 'i' : '.';
    char in_haltnot = ((in >> DBUS_DATA_START) & DMCONTROL_HALTNOT) ? 'h' : '.';
    unsigned int in_data = in >> 2;
    unsigned int in_address = in >> DBUS_ADDRESS_START;
 
    log_printf_lf(LOG_LVL_DEBUG,
            __FILE__, __LINE__, "scan",
            "%ub %s %c%c:%08x @%02x -> %s %c%c:%08x @%02x",
            field->num_bits,
            op_string[out_op], out_interrupt, out_haltnot, out_data,
            out_address,
            status_string[in_op], in_interrupt, in_haltnot, in_data,
            in_address);
}
 
static dbus_status_t dbus_scan(struct target *target, uint16_t *address_in,
        uint64_t *data_in, dbus_op_t op, uint16_t address_out, uint64_t data_out)
{
    riscv011_info_t *info = get_info(target);
    uint8_t in[8] = {0};
    uint8_t out[8] = {0};
    struct scan_field field = {
        .num_bits = info->addrbits + DBUS_OP_SIZE + DBUS_DATA_SIZE,
        .out_value = out,
        .in_value = in
    };
 
    assert(info->addrbits != 0);
 
    buf_set_u64(out, DBUS_OP_START, DBUS_OP_SIZE, op);
    buf_set_u64(out, DBUS_DATA_START, DBUS_DATA_SIZE, data_out);
    buf_set_u64(out, DBUS_ADDRESS_START, info->addrbits, address_out);
 
    /* Assume dbus is already selected. */
    jtag_add_dr_scan(target->tap, 1, &field, TAP_IDLE);
 
    int idle_count = info->dtmcontrol_idle + info->dbus_busy_delay;
 
    if (idle_count)
        jtag_add_runtest(idle_count, TAP_IDLE);
 
    int retval = jtag_execute_queue();
    if (retval != ERROR_OK) {
        LOG_ERROR("dbus_scan failed jtag scan");
        return DBUS_STATUS_FAILED;
    }
 
    if (data_in)
        *data_in = buf_get_u64(in, DBUS_DATA_START, DBUS_DATA_SIZE);
 
    if (address_in)
        *address_in = buf_get_u32(in, DBUS_ADDRESS_START, info->addrbits);
 
    dump_field(&field);
 
    return buf_get_u32(in, DBUS_OP_START, DBUS_OP_SIZE);
}
 
static uint64_t dbus_read(struct target *target, uint16_t address)
{
    uint64_t value;
    dbus_status_t status;
    uint16_t address_in;
 
    /* If the previous read/write was to the same address, we will get the read data
     * from the previous access.
     * While somewhat nonintuitive, this is an efficient way to get the data.
     */
 
    unsigned int i = 0;
    do {
        status = dbus_scan(target, &address_in, &value, DBUS_OP_READ, address, 0);
        if (status == DBUS_STATUS_BUSY)
            increase_dbus_busy_delay(target);
        if (status == DBUS_STATUS_FAILED) {
            LOG_ERROR("dbus_read(0x%x) failed!", address);
            return 0;
        }
    } while (((status == DBUS_STATUS_BUSY) || (address_in != address)) &&
            i++ < 256);
 
    if (status != DBUS_STATUS_SUCCESS)
        LOG_ERROR("failed read from 0x%x; value=0x%" PRIx64 ", status=%d\n", address, value, status);
 
    return value;
}
 
static void dbus_write(struct target *target, uint16_t address, uint64_t value)
{
    dbus_status_t status = DBUS_STATUS_BUSY;
    unsigned int i = 0;
    while (status == DBUS_STATUS_BUSY && i++ < 256) {
        status = dbus_scan(target, NULL, NULL, DBUS_OP_WRITE, address, value);
        if (status == DBUS_STATUS_BUSY)
            increase_dbus_busy_delay(target);
    }
    if (status != DBUS_STATUS_SUCCESS)
        LOG_ERROR("failed to write 0x%" PRIx64 " to 0x%x; status=%d\n", value, address, status);
}
 
/*** scans "class" ***/
 
typedef struct {
    /* Number of scans that space is reserved for. */
    unsigned int scan_count;
    /* Size reserved in memory for each scan, in bytes. */
    unsigned int scan_size;
    unsigned int next_scan;
    uint8_t *in;
    uint8_t *out;
    struct scan_field *field;
    const struct target *target;
} scans_t;
 
static scans_t *scans_new(struct target *target, unsigned int scan_count)
{
    scans_t *scans = malloc(sizeof(scans_t));
    if (!scans)
        goto error0;
    scans->scan_count = scan_count;
    /* This code also gets called before xlen is detected. */
    if (riscv_xlen(target))
        scans->scan_size = 2 + riscv_xlen(target) / 8;
    else
        scans->scan_size = 2 + 128 / 8;
    scans->next_scan = 0;
    scans->in = calloc(scans->scan_size, scans->scan_count);
    if (!scans->in)
        goto error1;
    scans->out = calloc(scans->scan_size, scans->scan_count);
    if (!scans->out)
        goto error2;
    scans->field = calloc(scans->scan_count, sizeof(struct scan_field));
    if (!scans->field)
        goto error3;
    scans->target = target;
    return scans;
 
error3:
    free(scans->out);
error2:
    free(scans->in);
error1:
    free(scans);
error0:
    return NULL;
}
 
static scans_t *scans_delete(scans_t *scans)
{
    assert(scans);
    free(scans->field);
    free(scans->out);
    free(scans->in);
    free(scans);
    return NULL;
}
 
static void scans_reset(scans_t *scans)
{
    scans->next_scan = 0;
}
 
static void scans_dump(scans_t *scans)
{
    for (unsigned int i = 0; i < scans->next_scan; i++)
        dump_field(&scans->field[i]);
}
 
static int scans_execute(scans_t *scans)
{
    int retval = jtag_execute_queue();
    if (retval != ERROR_OK) {
        LOG_ERROR("failed jtag scan: %d", retval);
        return retval;
    }
 
    scans_dump(scans);
 
    return ERROR_OK;
}
 
static void scans_add_write32(scans_t *scans, uint16_t address, uint32_t data,
        bool set_interrupt)
{
    const unsigned int i = scans->next_scan;
    int data_offset = scans->scan_size * i;
    add_dbus_scan(scans->target, &scans->field[i], scans->out + data_offset,
            scans->in + data_offset, DBUS_OP_WRITE, address,
            (set_interrupt ? DMCONTROL_INTERRUPT : 0) | DMCONTROL_HALTNOT | data);
    scans->next_scan++;
    assert(scans->next_scan <= scans->scan_count);
}
 
static void scans_add_write_jump(scans_t *scans, uint16_t address,
        bool set_interrupt)
{
    scans_add_write32(scans, address,
            jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*address))),
            set_interrupt);
}
 
static void scans_add_write_load(scans_t *scans, uint16_t address,
        unsigned int reg, slot_t slot, bool set_interrupt)
{
    scans_add_write32(scans, address, load_slot(scans->target, reg, slot),
            set_interrupt);
}
 
static void scans_add_write_store(scans_t *scans, uint16_t address,
        unsigned int reg, slot_t slot, bool set_interrupt)
{
    scans_add_write32(scans, address, store_slot(scans->target, reg, slot),
            set_interrupt);
}
 
static void scans_add_read32(scans_t *scans, uint16_t address, bool set_interrupt)
{
    assert(scans->next_scan < scans->scan_count);
    const unsigned int i = scans->next_scan;
    int data_offset = scans->scan_size * i;
    add_dbus_scan(scans->target, &scans->field[i], scans->out + data_offset,
            scans->in + data_offset, DBUS_OP_READ, address,
            (set_interrupt ? DMCONTROL_INTERRUPT : 0) | DMCONTROL_HALTNOT);
    scans->next_scan++;
}
 
static void scans_add_read(scans_t *scans, slot_t slot, bool set_interrupt)
{
    const struct target *target = scans->target;
    switch (riscv_xlen(target)) {
        case 32:
            scans_add_read32(scans, slot_offset(target, slot), set_interrupt);
            break;
        case 64:
            scans_add_read32(scans, slot_offset(target, slot), false);
            scans_add_read32(scans, slot_offset(target, slot) + 1, set_interrupt);
            break;
    }
}
 
static uint32_t scans_get_u32(scans_t *scans, unsigned int index,
        unsigned int first, unsigned int num)
{
    return buf_get_u32(scans->in + scans->scan_size * index, first, num);
}
 
static uint64_t scans_get_u64(scans_t *scans, unsigned int index,
        unsigned int first, unsigned int num)
{
    return buf_get_u64(scans->in + scans->scan_size * index, first, num);
}
 
/*** end of scans class ***/
 
static uint32_t dram_read32(struct target *target, unsigned int index)
{
    uint16_t address = dram_address(index);
    uint32_t value = dbus_read(target, address);
    return value;
}
 
static void dram_write32(struct target *target, unsigned int index, uint32_t value,
        bool set_interrupt)
{
    uint64_t dbus_value = DMCONTROL_HALTNOT | value;
    if (set_interrupt)
        dbus_value |= DMCONTROL_INTERRUPT;
    dbus_write(target, dram_address(index), dbus_value);
}
 
static bits_t read_bits(struct target *target)
{
    uint64_t value;
    dbus_status_t status;
    uint16_t address_in;
    riscv011_info_t *info = get_info(target);
 
    bits_t err_result = {
        .haltnot = 0,
        .interrupt = 0
    };
 
    do {
        unsigned int i = 0;
        do {
            status = dbus_scan(target, &address_in, &value, DBUS_OP_READ, 0, 0);
            if (status == DBUS_STATUS_BUSY) {
                if (address_in == (1<<info->addrbits) - 1 &&
                        value == (1ULL<<DBUS_DATA_SIZE) - 1) {
                    LOG_ERROR("TDO seems to be stuck high.");
                    return err_result;
                }
                increase_dbus_busy_delay(target);
            } else if (status == DBUS_STATUS_FAILED) {
                /* TODO: return an actual error */
                return err_result;
            }
        } while (status == DBUS_STATUS_BUSY && i++ < 256);
 
        if (i >= 256) {
            LOG_ERROR("Failed to read from 0x%x; status=%d", address_in, status);
            return err_result;
        }
    } while (address_in > 0x10 && address_in != DMCONTROL);
 
    bits_t result = {
        .haltnot = get_field(value, DMCONTROL_HALTNOT),
        .interrupt = get_field(value, DMCONTROL_INTERRUPT)
    };
    return result;
}
 
static int wait_for_debugint_clear(struct target *target, bool ignore_first)
{
    time_t start = time(NULL);
    if (ignore_first) {
        /* Throw away the results of the first read, since they'll contain the
         * result of the read that happened just before debugint was set.
         * (Assuming the last scan before calling this function was one that
         * sets debugint.) */
        read_bits(target);
    }
    while (1) {
        bits_t bits = read_bits(target);
        if (!bits.interrupt)
            return ERROR_OK;
        if (time(NULL) - start > riscv_command_timeout_sec) {
            LOG_ERROR("Timed out waiting for debug int to clear."
                  "Increase timeout with riscv set_command_timeout_sec.");
            return ERROR_FAIL;
        }
    }
}
 
static int dram_check32(struct target *target, unsigned int index,
        uint32_t expected)
{
    uint16_t address = dram_address(index);
    uint32_t actual = dbus_read(target, address);
    if (expected != actual) {
        LOG_ERROR("Wrote 0x%x to Debug RAM at %d, but read back 0x%x",
                expected, index, actual);
        return ERROR_FAIL;
    }
    return ERROR_OK;
}
 
static void cache_set32(struct target *target, unsigned int index, uint32_t data)
{
    riscv011_info_t *info = get_info(target);
    if (info->dram_cache[index].valid &&
            info->dram_cache[index].data == data) {
        /* This is already preset on the target. */
        LOG_DEBUG("cache[0x%x] = 0x%08x: DASM(0x%x) (hit)", index, data, data);
        return;
    }
    LOG_DEBUG("cache[0x%x] = 0x%08x: DASM(0x%x)", index, data, data);
    info->dram_cache[index].data = data;
    info->dram_cache[index].valid = true;
    info->dram_cache[index].dirty = true;
}
 
static void cache_set(struct target *target, slot_t slot, uint64_t data)
{
    unsigned int offset = slot_offset(target, slot);
    cache_set32(target, offset, data);
    if (riscv_xlen(target) > 32)
        cache_set32(target, offset + 1, data >> 32);
}
 
static void cache_set_jump(struct target *target, unsigned int index)
{
    cache_set32(target, index,
            jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*index))));
}
 
static void cache_set_load(struct target *target, unsigned int index,
        unsigned int reg, slot_t slot)
{
    uint16_t offset = DEBUG_RAM_START + 4 * slot_offset(target, slot);
    cache_set32(target, index, load(target, reg, ZERO, offset));
}
 
static void cache_set_store(struct target *target, unsigned int index,
        unsigned int reg, slot_t slot)
{
    uint16_t offset = DEBUG_RAM_START + 4 * slot_offset(target, slot);
    cache_set32(target, index, store(target, reg, ZERO, offset));
}
 
static void dump_debug_ram(struct target *target)
{
    for (unsigned int i = 0; i < DRAM_CACHE_SIZE; i++) {
        uint32_t value = dram_read32(target, i);
        LOG_ERROR("Debug RAM 0x%x: 0x%08x", i, value);
    }
}
 
/* Call this if the code you just ran writes to debug RAM entries 0 through 3. */
static void cache_invalidate(struct target *target)
{
    riscv011_info_t *info = get_info(target);
    for (unsigned int i = 0; i < info->dramsize; i++) {
        info->dram_cache[i].valid = false;
        info->dram_cache[i].dirty = false;
    }
}
 
/* Called by cache_write() after the program has run. Also call this if you're
 * running programs without calling cache_write(). */
static void cache_clean(struct target *target)
{
    riscv011_info_t *info = get_info(target);
    for (unsigned int i = 0; i < info->dramsize; i++) {
        if (i >= 4)
            info->dram_cache[i].valid = false;
        info->dram_cache[i].dirty = false;
    }
}
 
static int cache_check(struct target *target)
{
    riscv011_info_t *info = get_info(target);
    int error = 0;
 
    for (unsigned int i = 0; i < info->dramsize; i++) {
        if (info->dram_cache[i].valid && !info->dram_cache[i].dirty) {
            if (dram_check32(target, i, info->dram_cache[i].data) != ERROR_OK)
                error++;
        }
    }
 
    if (error) {
        dump_debug_ram(target);
        return ERROR_FAIL;
    }
 
    return ERROR_OK;
}
 
#define CACHE_NO_READ   128
static int cache_write(struct target *target, unsigned int address, bool run)
{
    LOG_DEBUG("enter");
    riscv011_info_t *info = get_info(target);
    scans_t *scans = scans_new(target, info->dramsize + 2);
    if (!scans)
        return ERROR_FAIL;
 
    unsigned int last = info->dramsize;
    for (unsigned int i = 0; i < info->dramsize; i++) {
        if (info->dram_cache[i].dirty)
            last = i;
    }
 
    if (last == info->dramsize) {
        /* Nothing needs to be written to RAM. */
        dbus_write(target, DMCONTROL, DMCONTROL_HALTNOT | (run ? DMCONTROL_INTERRUPT : 0));
 
    } else {
        for (unsigned int i = 0; i < info->dramsize; i++) {
            if (info->dram_cache[i].dirty) {
                bool set_interrupt = (i == last && run);
                scans_add_write32(scans, i, info->dram_cache[i].data,
                        set_interrupt);
            }
        }
    }
 
    if (run || address < CACHE_NO_READ) {
        /* Throw away the results of the first read, since it'll contain the
         * result of the read that happened just before debugint was set. */
        scans_add_read32(scans, address, false);
 
        /* This scan contains the results of the read the caller requested, as
         * well as an interrupt bit worth looking at. */
        scans_add_read32(scans, address, false);
    }
 
    int retval = scans_execute(scans);
    if (retval != ERROR_OK) {
        scans_delete(scans);
        LOG_ERROR("JTAG execute failed.");
        return retval;
    }
 
    int errors = 0;
    for (unsigned int i = 0; i < scans->next_scan; i++) {
        dbus_status_t status = scans_get_u32(scans, i, DBUS_OP_START,
                DBUS_OP_SIZE);
        switch (status) {
            case DBUS_STATUS_SUCCESS:
                break;
            case DBUS_STATUS_FAILED:
                LOG_ERROR("Debug RAM write failed. Hardware error?");
                scans_delete(scans);
                return ERROR_FAIL;
            case DBUS_STATUS_BUSY:
                errors++;
                break;
            default:
                LOG_ERROR("Got invalid bus access status: %d", status);
                scans_delete(scans);
                return ERROR_FAIL;
        }
    }
 
    if (errors) {
        increase_dbus_busy_delay(target);
 
        /* Try again, using the slow careful code.
         * Write all RAM, just to be extra cautious. */
        for (unsigned int i = 0; i < info->dramsize; i++) {
            if (i == last && run)
                dram_write32(target, last, info->dram_cache[last].data, true);
            else
                dram_write32(target, i, info->dram_cache[i].data, false);
            info->dram_cache[i].dirty = false;
        }
        if (run)
            cache_clean(target);
 
        if (wait_for_debugint_clear(target, true) != ERROR_OK) {
            LOG_ERROR("Debug interrupt didn't clear.");
            dump_debug_ram(target);
            scans_delete(scans);
            return ERROR_FAIL;
        }
 
    } else {
        if (run) {
            cache_clean(target);
        } else {
            for (unsigned int i = 0; i < info->dramsize; i++)
                info->dram_cache[i].dirty = false;
        }
 
        if (run || address < CACHE_NO_READ) {
            int interrupt = scans_get_u32(scans, scans->next_scan-1,
                    DBUS_DATA_START + 33, 1);
            if (interrupt) {
                increase_interrupt_high_delay(target);
                /* Slow path wait for it to clear. */
                if (wait_for_debugint_clear(target, false) != ERROR_OK) {
                    LOG_ERROR("Debug interrupt didn't clear.");
                    dump_debug_ram(target);
                    scans_delete(scans);
                    return ERROR_FAIL;
                }
            } else {
                /* We read a useful value in that last scan. */
                unsigned int read_addr = scans_get_u32(scans, scans->next_scan-1,
                        DBUS_ADDRESS_START, info->addrbits);
                if (read_addr != address) {
                    LOG_INFO("Got data from 0x%x but expected it from 0x%x",
                            read_addr, address);
                }
                info->dram_cache[read_addr].data =
                    scans_get_u32(scans, scans->next_scan-1, DBUS_DATA_START, 32);
                info->dram_cache[read_addr].valid = true;
            }
        }
    }
 
    scans_delete(scans);
    LOG_DEBUG("exit");
 
    return ERROR_OK;
}
 
static uint32_t cache_get32(struct target *target, unsigned int address)
{
    riscv011_info_t *info = get_info(target);
    if (!info->dram_cache[address].valid) {
        info->dram_cache[address].data = dram_read32(target, address);
        info->dram_cache[address].valid = true;
    }
    return info->dram_cache[address].data;
}
 
static uint64_t cache_get(struct target *target, slot_t slot)
{
    unsigned int offset = slot_offset(target, slot);
    uint64_t value = cache_get32(target, offset);
    if (riscv_xlen(target) > 32)
        value |= ((uint64_t) cache_get32(target, offset + 1)) << 32;
    return value;
}
 
/* Write instruction that jumps from the specified word in Debug RAM to resume
 * in Debug ROM. */
static void dram_write_jump(struct target *target, unsigned int index,
        bool set_interrupt)
{
    dram_write32(target, index,
            jal(0, (uint32_t) (DEBUG_ROM_RESUME - (DEBUG_RAM_START + 4*index))),
            set_interrupt);
}
 
static int wait_for_state(struct target *target, enum target_state state)
{
    time_t start = time(NULL);
    while (1) {
        int result = riscv011_poll(target);
        if (result != ERROR_OK)
            return result;
        if (target->state == state)
            return ERROR_OK;
        if (time(NULL) - start > riscv_command_timeout_sec) {
            LOG_ERROR("Timed out waiting for state %d. "
                  "Increase timeout with riscv set_command_timeout_sec.", state);
            return ERROR_FAIL;
        }
    }
}
 
static int read_remote_csr(struct target *target, uint64_t *value, uint32_t csr)
{
    riscv011_info_t *info = get_info(target);
    cache_set32(target, 0, csrr(S0, csr));
    cache_set_store(target, 1, S0, SLOT0);
    cache_set_jump(target, 2);
    if (cache_write(target, 4, true) != ERROR_OK)
        return ERROR_FAIL;
    *value = cache_get(target, SLOT0);
    LOG_DEBUG("csr 0x%x = 0x%" PRIx64, csr, *value);
 
    uint32_t exception = cache_get32(target, info->dramsize-1);
    if (exception) {
        LOG_WARNING("Got exception 0x%x when reading %s", exception,
                gdb_regno_name(GDB_REGNO_CSR0 + csr));
        *value = ~0;
        return ERROR_FAIL;
    }
 
    return ERROR_OK;
}
 
static int write_remote_csr(struct target *target, uint32_t csr, uint64_t value)
{
    LOG_DEBUG("csr 0x%x <- 0x%" PRIx64, csr, value);
    cache_set_load(target, 0, S0, SLOT0);
    cache_set32(target, 1, csrw(S0, csr));
    cache_set_jump(target, 2);
    cache_set(target, SLOT0, value);
    if (cache_write(target, 4, true) != ERROR_OK)
        return ERROR_FAIL;
 
    return ERROR_OK;
}
 
static int write_gpr(struct target *target, unsigned int gpr, uint64_t value)
{
    cache_set_load(target, 0, gpr, SLOT0);
    cache_set_jump(target, 1);
    cache_set(target, SLOT0, value);
    if (cache_write(target, 4, true) != ERROR_OK)
        return ERROR_FAIL;
    return ERROR_OK;
}
 
static int maybe_read_tselect(struct target *target)
{
    riscv011_info_t *info = get_info(target);
 
    if (info->tselect_dirty) {
        int result = read_remote_csr(target, &info->tselect, CSR_TSELECT);
        if (result != ERROR_OK)
            return result;
        info->tselect_dirty = false;
    }
 
    return ERROR_OK;
}
 
static int maybe_write_tselect(struct target *target)
{
    riscv011_info_t *info = get_info(target);
 
    if (!info->tselect_dirty) {
        int result = write_remote_csr(target, CSR_TSELECT, info->tselect);
        if (result != ERROR_OK)
            return result;
        info->tselect_dirty = true;
    }
 
    return ERROR_OK;
}
 
static int execute_resume(struct target *target, bool step)
{
    riscv011_info_t *info = get_info(target);
 
    LOG_DEBUG("step=%d", step);
 
    maybe_write_tselect(target);
 
    /* TODO: check if dpc is dirty (which also is true if an exception was hit
     * at any time) */
    cache_set_load(target, 0, S0, SLOT0);
    cache_set32(target, 1, csrw(S0, CSR_DPC));
    cache_set_jump(target, 2);
    cache_set(target, SLOT0, info->dpc);
    if (cache_write(target, 4, true) != ERROR_OK)
        return ERROR_FAIL;
 
    struct reg *mstatus_reg = &target->reg_cache->reg_list[GDB_REGNO_MSTATUS];
    if (mstatus_reg->valid) {
        uint64_t mstatus_user = buf_get_u64(mstatus_reg->value, 0, riscv_xlen(target));
        if (mstatus_user != info->mstatus_actual) {
            cache_set_load(target, 0, S0, SLOT0);
            cache_set32(target, 1, csrw(S0, CSR_MSTATUS));
            cache_set_jump(target, 2);
            cache_set(target, SLOT0, mstatus_user);
            if (cache_write(target, 4, true) != ERROR_OK)
                return ERROR_FAIL;
        }
    }
 
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKM, riscv_ebreakm);
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKS, riscv_ebreaks);
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKU, riscv_ebreaku);
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKH, 1);
    info->dcsr &= ~DCSR_HALT;
 
    if (step)
        info->dcsr |= DCSR_STEP;
    else
        info->dcsr &= ~DCSR_STEP;
 
    dram_write32(target, 0, lw(S0, ZERO, DEBUG_RAM_START + 16), false);
    dram_write32(target, 1, csrw(S0, CSR_DCSR), false);
    dram_write32(target, 2, fence_i(), false);
    dram_write_jump(target, 3, false);
 
    /* Write DCSR value, set interrupt and clear haltnot. */
    uint64_t dbus_value = DMCONTROL_INTERRUPT | info->dcsr;
    dbus_write(target, dram_address(4), dbus_value);
 
    cache_invalidate(target);
 
    if (wait_for_debugint_clear(target, true) != ERROR_OK) {
        LOG_ERROR("Debug interrupt didn't clear.");
        return ERROR_FAIL;
    }
 
    target->state = TARGET_RUNNING;
    register_cache_invalidate(target->reg_cache);
 
    return ERROR_OK;
}
 
/* Execute a step, and wait for reentry into Debug Mode. */
static int full_step(struct target *target, bool announce)
{
    int result = execute_resume(target, true);
    if (result != ERROR_OK)
        return result;
    time_t start = time(NULL);
    while (1) {
        result = poll_target(target, announce);
        if (result != ERROR_OK)
            return result;
        if (target->state != TARGET_DEBUG_RUNNING)
            break;
        if (time(NULL) - start > riscv_command_timeout_sec) {
            LOG_ERROR("Timed out waiting for step to complete."
                    "Increase timeout with riscv set_command_timeout_sec");
            return ERROR_FAIL;
        }
    }
    return ERROR_OK;
}
 
static int resume(struct target *target, int debug_execution, bool step)
{
    if (debug_execution) {
        LOG_ERROR("TODO: debug_execution is true");
        return ERROR_FAIL;
    }
 
    return execute_resume(target, step);
}
 
static uint64_t reg_cache_get(struct target *target, unsigned int number)
{
    struct reg *r = &target->reg_cache->reg_list[number];
    if (!r->valid) {
        LOG_ERROR("Register cache entry for %d is invalid!", number);
        assert(r->valid);
    }
    uint64_t value = buf_get_u64(r->value, 0, r->size);
    LOG_DEBUG("%s = 0x%" PRIx64, r->name, value);
    return value;
}
 
static void reg_cache_set(struct target *target, unsigned int number,
        uint64_t value)
{
    struct reg *r = &target->reg_cache->reg_list[number];
    LOG_DEBUG("%s <= 0x%" PRIx64, r->name, value);
    r->valid = true;
    buf_set_u64(r->value, 0, r->size, value);
}
 
static int update_mstatus_actual(struct target *target)
{
    struct reg *mstatus_reg = &target->reg_cache->reg_list[GDB_REGNO_MSTATUS];
    if (mstatus_reg->valid) {
        /* We previously made it valid. */
        return ERROR_OK;
    }
 
    /* Force reading the register. In that process mstatus_actual will be
     * updated. */
    riscv_reg_t mstatus;
    return get_register(target, &mstatus, GDB_REGNO_MSTATUS);
}
 
/*** OpenOCD target functions. ***/
 
static int register_read(struct target *target, riscv_reg_t *value, int regnum)
{
    riscv011_info_t *info = get_info(target);
    if (regnum >= GDB_REGNO_CSR0 && regnum <= GDB_REGNO_CSR4095) {
        cache_set32(target, 0, csrr(S0, regnum - GDB_REGNO_CSR0));
        cache_set_store(target, 1, S0, SLOT0);
        cache_set_jump(target, 2);
    } else {
        LOG_ERROR("Don't know how to read register %d", regnum);
        return ERROR_FAIL;
    }
 
    if (cache_write(target, 4, true) != ERROR_OK)
        return ERROR_FAIL;
 
    uint32_t exception = cache_get32(target, info->dramsize-1);
    if (exception) {
        LOG_WARNING("Got exception 0x%x when reading %s", exception, gdb_regno_name(regnum));
        *value = ~0;
        return ERROR_FAIL;
    }
 
    *value = cache_get(target, SLOT0);
    LOG_DEBUG("reg[%d]=0x%" PRIx64, regnum, *value);
 
    if (regnum == GDB_REGNO_MSTATUS)
        info->mstatus_actual = *value;
 
    return ERROR_OK;
}
 
/* Write the register. No caching or games. */
static int register_write(struct target *target, unsigned int number,
        uint64_t value)
{
    riscv011_info_t *info = get_info(target);
 
    maybe_write_tselect(target);
 
    if (number == S0) {
        cache_set_load(target, 0, S0, SLOT0);
        cache_set32(target, 1, csrw(S0, CSR_DSCRATCH0));
        cache_set_jump(target, 2);
    } else if (number == S1) {
        cache_set_load(target, 0, S0, SLOT0);
        cache_set_store(target, 1, S0, SLOT_LAST);
        cache_set_jump(target, 2);
    } else if (number <= GDB_REGNO_XPR31) {
        cache_set_load(target, 0, number - GDB_REGNO_ZERO, SLOT0);
        cache_set_jump(target, 1);
    } else if (number == GDB_REGNO_PC) {
        info->dpc = value;
        return ERROR_OK;
    } else if (number >= GDB_REGNO_FPR0 && number <= GDB_REGNO_FPR31) {
        int result = update_mstatus_actual(target);
        if (result != ERROR_OK)
            return result;
        unsigned int i = 0;
        if ((info->mstatus_actual & MSTATUS_FS) == 0) {
            info->mstatus_actual = set_field(info->mstatus_actual, MSTATUS_FS, 1);
            cache_set_load(target, i++, S0, SLOT1);
            cache_set32(target, i++, csrw(S0, CSR_MSTATUS));
            cache_set(target, SLOT1, info->mstatus_actual);
        }
 
        if (riscv_xlen(target) == 32)
            cache_set32(target, i++, flw(number - GDB_REGNO_FPR0, 0, DEBUG_RAM_START + 16));
        else
            cache_set32(target, i++, fld(number - GDB_REGNO_FPR0, 0, DEBUG_RAM_START + 16));
        cache_set_jump(target, i++);
    } else if (number >= GDB_REGNO_CSR0 && number <= GDB_REGNO_CSR4095) {
        cache_set_load(target, 0, S0, SLOT0);
        cache_set32(target, 1, csrw(S0, number - GDB_REGNO_CSR0));
        cache_set_jump(target, 2);
 
        if (number == GDB_REGNO_MSTATUS)
            info->mstatus_actual = value;
    } else if (number == GDB_REGNO_PRIV) {
        info->dcsr = set_field(info->dcsr, DCSR_PRV, value);
        return ERROR_OK;
    } else {
        LOG_ERROR("Don't know how to write register %d", number);
        return ERROR_FAIL;
    }
 
    cache_set(target, SLOT0, value);
    if (cache_write(target, info->dramsize - 1, true) != ERROR_OK)
        return ERROR_FAIL;
 
    uint32_t exception = cache_get32(target, info->dramsize-1);
    if (exception) {
        LOG_WARNING("Got exception 0x%x when writing %s", exception,
                gdb_regno_name(number));
        return ERROR_FAIL;
    }
 
    return ERROR_OK;
}
 
static int get_register(struct target *target, riscv_reg_t *value, int regid)
{
    riscv011_info_t *info = get_info(target);
 
    maybe_write_tselect(target);
 
    if (regid <= GDB_REGNO_XPR31) {
        *value = reg_cache_get(target, regid);
    } else if (regid == GDB_REGNO_PC) {
        *value = info->dpc;
    } else if (regid >= GDB_REGNO_FPR0 && regid <= GDB_REGNO_FPR31) {
        int result = update_mstatus_actual(target);
        if (result != ERROR_OK)
            return result;
        unsigned int i = 0;
        if ((info->mstatus_actual & MSTATUS_FS) == 0) {
            info->mstatus_actual = set_field(info->mstatus_actual, MSTATUS_FS, 1);
            cache_set_load(target, i++, S0, SLOT1);
            cache_set32(target, i++, csrw(S0, CSR_MSTATUS));
            cache_set(target, SLOT1, info->mstatus_actual);
        }
 
        if (riscv_xlen(target) == 32)
            cache_set32(target, i++, fsw(regid - GDB_REGNO_FPR0, 0, DEBUG_RAM_START + 16));
        else
            cache_set32(target, i++, fsd(regid - GDB_REGNO_FPR0, 0, DEBUG_RAM_START + 16));
        cache_set_jump(target, i++);
 
        if (cache_write(target, 4, true) != ERROR_OK)
            return ERROR_FAIL;
    } else if (regid == GDB_REGNO_PRIV) {
        *value = get_field(info->dcsr, DCSR_PRV);
    } else {
        int result = register_read(target, value, regid);
        if (result != ERROR_OK)
            return result;
    }
 
    if (regid == GDB_REGNO_MSTATUS)
        target->reg_cache->reg_list[regid].valid = true;
 
    return ERROR_OK;
}
 
static int set_register(struct target *target, int regid, uint64_t value)
{
    return register_write(target, regid, value);
}
 
static int halt(struct target *target)
{
    LOG_DEBUG("riscv_halt()");
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    cache_set32(target, 0, csrsi(CSR_DCSR, DCSR_HALT));
    cache_set32(target, 1, csrr(S0, CSR_MHARTID));
    cache_set32(target, 2, sw(S0, ZERO, SETHALTNOT));
    cache_set_jump(target, 3);
 
    if (cache_write(target, 4, true) != ERROR_OK) {
        LOG_ERROR("cache_write() failed.");
        return ERROR_FAIL;
    }
 
    return ERROR_OK;
}
 
static void deinit_target(struct target *target)
{
    LOG_DEBUG("riscv_deinit_target()");
    struct riscv_info *info = target->arch_info;
    if (!info)
        return;
 
    free(info->version_specific);
    info->version_specific = NULL;
}
 
static int strict_step(struct target *target, bool announce)
{
    LOG_DEBUG("enter");
 
    struct watchpoint *watchpoint = target->watchpoints;
    while (watchpoint) {
        riscv_remove_watchpoint(target, watchpoint);
        watchpoint = watchpoint->next;
    }
 
    int result = full_step(target, announce);
    if (result != ERROR_OK)
        return result;
 
    watchpoint = target->watchpoints;
    while (watchpoint) {
        riscv_add_watchpoint(target, watchpoint);
        watchpoint = watchpoint->next;
    }
 
    return ERROR_OK;
}
 
static int step(struct target *target, int current, target_addr_t address,
        int handle_breakpoints)
{
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    if (!current) {
        if (riscv_xlen(target) > 32) {
            LOG_WARNING("Asked to resume at 32-bit PC on %d-bit target.",
                    riscv_xlen(target));
        }
        int result = register_write(target, GDB_REGNO_PC, address);
        if (result != ERROR_OK)
            return result;
    }
 
    if (handle_breakpoints) {
        int result = strict_step(target, true);
        if (result != ERROR_OK)
            return result;
    } else {
        return full_step(target, false);
    }
 
    return ERROR_OK;
}
 
static int examine(struct target *target)
{
    /* Don't need to select dbus, since the first thing we do is read dtmcontrol. */
 
    uint32_t dtmcontrol = dtmcontrol_scan(target, 0);
    LOG_DEBUG("dtmcontrol=0x%x", dtmcontrol);
    LOG_DEBUG("  addrbits=%d", get_field(dtmcontrol, DTMCONTROL_ADDRBITS));
    LOG_DEBUG("  version=%d", get_field(dtmcontrol, DTMCONTROL_VERSION));
    LOG_DEBUG("  idle=%d", get_field(dtmcontrol, DTMCONTROL_IDLE));
    if (dtmcontrol == 0) {
        LOG_ERROR("dtmcontrol is 0. Check JTAG connectivity/board power.");
        return ERROR_FAIL;
    }
    if (get_field(dtmcontrol, DTMCONTROL_VERSION) != 0) {
        LOG_ERROR("Unsupported DTM version %d. (dtmcontrol=0x%x)",
                get_field(dtmcontrol, DTMCONTROL_VERSION), dtmcontrol);
        return ERROR_FAIL;
    }
 
    RISCV_INFO(r);
 
    riscv011_info_t *info = get_info(target);
    info->addrbits = get_field(dtmcontrol, DTMCONTROL_ADDRBITS);
    info->dtmcontrol_idle = get_field(dtmcontrol, DTMCONTROL_IDLE);
    if (info->dtmcontrol_idle == 0) {
        /* Some old SiFive cores don't set idle but need it to be 1. */
        uint32_t idcode = idcode_scan(target);
        if (idcode == 0x10e31913)
            info->dtmcontrol_idle = 1;
    }
 
    uint32_t dminfo = dbus_read(target, DMINFO);
    LOG_DEBUG("dminfo: 0x%08x", dminfo);
    LOG_DEBUG("  abussize=0x%x", get_field(dminfo, DMINFO_ABUSSIZE));
    LOG_DEBUG("  serialcount=0x%x", get_field(dminfo, DMINFO_SERIALCOUNT));
    LOG_DEBUG("  access128=%d", get_field(dminfo, DMINFO_ACCESS128));
    LOG_DEBUG("  access64=%d", get_field(dminfo, DMINFO_ACCESS64));
    LOG_DEBUG("  access32=%d", get_field(dminfo, DMINFO_ACCESS32));
    LOG_DEBUG("  access16=%d", get_field(dminfo, DMINFO_ACCESS16));
    LOG_DEBUG("  access8=%d", get_field(dminfo, DMINFO_ACCESS8));
    LOG_DEBUG("  dramsize=0x%x", get_field(dminfo, DMINFO_DRAMSIZE));
    LOG_DEBUG("  authenticated=0x%x", get_field(dminfo, DMINFO_AUTHENTICATED));
    LOG_DEBUG("  authbusy=0x%x", get_field(dminfo, DMINFO_AUTHBUSY));
    LOG_DEBUG("  authtype=0x%x", get_field(dminfo, DMINFO_AUTHTYPE));
    LOG_DEBUG("  version=0x%x", get_field(dminfo, DMINFO_VERSION));
 
    if (get_field(dminfo, DMINFO_VERSION) != 1) {
        LOG_ERROR("OpenOCD only supports Debug Module version 1, not %d "
                "(dminfo=0x%x)", get_field(dminfo, DMINFO_VERSION), dminfo);
        return ERROR_FAIL;
    }
 
    info->dramsize = get_field(dminfo, DMINFO_DRAMSIZE) + 1;
 
    if (get_field(dminfo, DMINFO_AUTHTYPE) != 0) {
        LOG_ERROR("Authentication required by RISC-V core but not "
                "supported by OpenOCD. dminfo=0x%x", dminfo);
        return ERROR_FAIL;
    }
 
    /* Pretend this is a 32-bit system until we have found out the true value. */
    r->xlen = 32;
 
    /* Figure out XLEN, and test writing all of Debug RAM while we're at it. */
    cache_set32(target, 0, xori(S1, ZERO, -1));
    /* 0xffffffff  0xffffffff:ffffffff  0xffffffff:ffffffff:ffffffff:ffffffff */
    cache_set32(target, 1, srli(S1, S1, 31));
    /* 0x00000001  0x00000001:ffffffff  0x00000001:ffffffff:ffffffff:ffffffff */
    cache_set32(target, 2, sw(S1, ZERO, DEBUG_RAM_START));
    cache_set32(target, 3, srli(S1, S1, 31));
    /* 0x00000000  0x00000000:00000003  0x00000000:00000003:ffffffff:ffffffff */
    cache_set32(target, 4, sw(S1, ZERO, DEBUG_RAM_START + 4));
    cache_set_jump(target, 5);
    for (unsigned int i = 6; i < info->dramsize; i++)
        cache_set32(target, i, i * 0x01020304);
 
    cache_write(target, 0, false);
 
    /* Check that we can actually read/write dram. */
    if (cache_check(target) != ERROR_OK)
        return ERROR_FAIL;
 
    cache_write(target, 0, true);
    cache_invalidate(target);
 
    uint32_t word0 = cache_get32(target, 0);
    uint32_t word1 = cache_get32(target, 1);
    struct riscv_info *generic_info = riscv_info(target);
    if (word0 == 1 && word1 == 0) {
        generic_info->xlen = 32;
    } else if (word0 == 0xffffffff && word1 == 3) {
        generic_info->xlen = 64;
    } else if (word0 == 0xffffffff && word1 == 0xffffffff) {
        generic_info->xlen = 128;
    } else {
        uint32_t exception = cache_get32(target, info->dramsize-1);
        LOG_ERROR("Failed to discover xlen; word0=0x%x, word1=0x%x, exception=0x%x",
                word0, word1, exception);
        dump_debug_ram(target);
        return ERROR_FAIL;
    }
    LOG_DEBUG("Discovered XLEN is %d", riscv_xlen(target));
 
    if (read_remote_csr(target, &r->misa, CSR_MISA) != ERROR_OK) {
        const unsigned int old_csr_misa = 0xf10;
        LOG_WARNING("Failed to read misa at 0x%x; trying 0x%x.", CSR_MISA,
                old_csr_misa);
        if (read_remote_csr(target, &r->misa, old_csr_misa) != ERROR_OK) {
            /* Maybe this is an old core that still has $misa at the old
             * address. */
            LOG_ERROR("Failed to read misa at 0x%x.", old_csr_misa);
            return ERROR_FAIL;
        }
    }
 
    /* Update register list to match discovered XLEN/supported extensions. */
    riscv_init_registers(target);
 
    info->never_halted = true;
 
    int result = riscv011_poll(target);
    if (result != ERROR_OK)
        return result;
 
    target_set_examined(target);
    riscv_set_current_hartid(target, 0);
    for (size_t i = 0; i < 32; ++i)
        reg_cache_set(target, i, -1);
    LOG_INFO("Examined RISCV core; XLEN=%d, misa=0x%" PRIx64,
            riscv_xlen(target), r->misa);
 
    return ERROR_OK;
}
 
static riscv_error_t handle_halt_routine(struct target *target)
{
    riscv011_info_t *info = get_info(target);
 
    scans_t *scans = scans_new(target, 256);
    if (!scans)
        return RE_FAIL;
 
    /* Read all GPRs as fast as we can, because gdb is going to ask for them
     * anyway. Reading them one at a time is much slower. */
 
    /* Write the jump back to address 1. */
    scans_add_write_jump(scans, 1, false);
    for (int reg = 1; reg < 32; reg++) {
        if (reg == S0 || reg == S1)
            continue;
 
        /* Write store instruction. */
        scans_add_write_store(scans, 0, reg, SLOT0, true);
 
        /* Read value. */
        scans_add_read(scans, SLOT0, false);
    }
 
    /* Write store of s0 at index 1. */
    scans_add_write_store(scans, 1, S0, SLOT0, false);
    /* Write jump at index 2. */
    scans_add_write_jump(scans, 2, false);
 
    /* Read S1 from debug RAM */
    scans_add_write_load(scans, 0, S0, SLOT_LAST, true);
    /* Read value. */
    scans_add_read(scans, SLOT0, false);
 
    /* Read S0 from dscratch */
    unsigned int csr[] = {CSR_DSCRATCH0, CSR_DPC, CSR_DCSR};
    for (unsigned int i = 0; i < ARRAY_SIZE(csr); i++) {
        scans_add_write32(scans, 0, csrr(S0, csr[i]), true);
        scans_add_read(scans, SLOT0, false);
    }
 
    /* Final read to get the last value out. */
    scans_add_read32(scans, 4, false);
 
    int retval = scans_execute(scans);
    if (retval != ERROR_OK) {
        LOG_ERROR("JTAG execute failed: %d", retval);
        goto error;
    }
 
    unsigned int dbus_busy = 0;
    unsigned int interrupt_set = 0;
    unsigned int result = 0;
    uint64_t value = 0;
    reg_cache_set(target, 0, 0);
    /* The first scan result is the result from something old we don't care
     * about. */
    for (unsigned int i = 1; i < scans->next_scan && dbus_busy == 0; i++) {
        dbus_status_t status = scans_get_u32(scans, i, DBUS_OP_START,
                DBUS_OP_SIZE);
        uint64_t data = scans_get_u64(scans, i, DBUS_DATA_START, DBUS_DATA_SIZE);
        uint32_t address = scans_get_u32(scans, i, DBUS_ADDRESS_START,
                info->addrbits);
        switch (status) {
            case DBUS_STATUS_SUCCESS:
                break;
            case DBUS_STATUS_FAILED:
                LOG_ERROR("Debug access failed. Hardware error?");
                goto error;
            case DBUS_STATUS_BUSY:
                dbus_busy++;
                break;
            default:
                LOG_ERROR("Got invalid bus access status: %d", status);
                goto error;
        }
        if (data & DMCONTROL_INTERRUPT) {
            interrupt_set++;
            break;
        }
        if (address == 4 || address == 5) {
            unsigned int reg;
            switch (result) {
                case 0:
                    reg = 1;
                    break;
                case 1:
                    reg = 2;
                    break;
                case 2:
                    reg = 3;
                    break;
                case 3:
                    reg = 4;
                    break;
                case 4:
                    reg = 5;
                    break;
                case 5:
                    reg = 6;
                    break;
                case 6:
                    reg = 7;
                    break;
                    /* S0 */
                    /* S1 */
                case 7:
                    reg = 10;
                    break;
                case 8:
                    reg = 11;
                    break;
                case 9:
                    reg = 12;
                    break;
                case 10:
                    reg = 13;
                    break;
                case 11:
                    reg = 14;
                    break;
                case 12:
                    reg = 15;
                    break;
                case 13:
                    reg = 16;
                    break;
                case 14:
                    reg = 17;
                    break;
                case 15:
                    reg = 18;
                    break;
                case 16:
                    reg = 19;
                    break;
                case 17:
                    reg = 20;
                    break;
                case 18:
                    reg = 21;
                    break;
                case 19:
                    reg = 22;
                    break;
                case 20:
                    reg = 23;
                    break;
                case 21:
                    reg = 24;
                    break;
                case 22:
                    reg = 25;
                    break;
                case 23:
                    reg = 26;
                    break;
                case 24:
                    reg = 27;
                    break;
                case 25:
                    reg = 28;
                    break;
                case 26:
                    reg = 29;
                    break;
                case 27:
                    reg = 30;
                    break;
                case 28:
                    reg = 31;
                    break;
                case 29:
                    reg = S1;
                    break;
                case 30:
                    reg = S0;
                    break;
                case 31:
                    reg = CSR_DPC;
                    break;
                case 32:
                    reg = CSR_DCSR;
                    break;
                default:
                    assert(0);
                    LOG_ERROR("Got invalid register result %d", result);
                    goto error;
            }
            if (riscv_xlen(target) == 32) {
                reg_cache_set(target, reg, data & 0xffffffff);
                result++;
            } else if (riscv_xlen(target) == 64) {
                if (address == 4) {
                    value = data & 0xffffffff;
                } else if (address == 5) {
                    reg_cache_set(target, reg, ((data & 0xffffffff) << 32) | value);
                    value = 0;
                    result++;
                }
            }
        }
    }
 
    scans_delete(scans);
 
    if (dbus_busy) {
        increase_dbus_busy_delay(target);
        return RE_AGAIN;
    }
    if (interrupt_set) {
        increase_interrupt_high_delay(target);
        return RE_AGAIN;
    }
 
    /* TODO: get rid of those 2 variables and talk to the cache directly. */
    info->dpc = reg_cache_get(target, CSR_DPC);
    info->dcsr = reg_cache_get(target, CSR_DCSR);
 
    cache_invalidate(target);
 
    return RE_OK;
 
error:
    scans_delete(scans);
    return RE_FAIL;
}
 
static int handle_halt(struct target *target, bool announce)
{
    riscv011_info_t *info = get_info(target);
    target->state = TARGET_HALTED;
 
    riscv_error_t re;
    do {
        re = handle_halt_routine(target);
    } while (re == RE_AGAIN);
    if (re != RE_OK) {
        LOG_ERROR("handle_halt_routine failed");
        return ERROR_FAIL;
    }
 
    int cause = get_field(info->dcsr, DCSR_CAUSE);
    switch (cause) {
        case DCSR_CAUSE_SWBP:
            target->debug_reason = DBG_REASON_BREAKPOINT;
            break;
        case DCSR_CAUSE_HWBP:
            target->debug_reason = DBG_REASON_WATCHPOINT;
            break;
        case DCSR_CAUSE_DEBUGINT:
            target->debug_reason = DBG_REASON_DBGRQ;
            break;
        case DCSR_CAUSE_STEP:
            target->debug_reason = DBG_REASON_SINGLESTEP;
            break;
        case DCSR_CAUSE_HALT:
        default:
            LOG_ERROR("Invalid halt cause %d in DCSR (0x%" PRIx64 ")",
                    cause, info->dcsr);
    }
 
    if (info->never_halted) {
        info->never_halted = false;
 
        int result = maybe_read_tselect(target);
        if (result != ERROR_OK)
            return result;
        riscv_enumerate_triggers(target);
    }
 
    if (target->debug_reason == DBG_REASON_BREAKPOINT) {
        int retval;
        if (riscv_semihosting(target, &retval) != 0)
            return retval;
    }
 
    if (announce)
        target_call_event_callbacks(target, TARGET_EVENT_HALTED);
 
    const char *cause_string[] = {
        "none",
        "software breakpoint",
        "hardware trigger",
        "debug interrupt",
        "step",
        "halt"
    };
    /* This is logged to the user so that gdb will show it when a user types
     * 'monitor reset init'. At that time gdb appears to have the pc cached
     * still so if a user manually inspects the pc it will still have the old
     * value. */
    LOG_USER("halted at 0x%" PRIx64 " due to %s", info->dpc, cause_string[cause]);
 
    return ERROR_OK;
}
 
static int poll_target(struct target *target, bool announce)
{
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    /* Inhibit debug logging during poll(), which isn't usually interesting and
     * just fills up the screen/logs with clutter. */
    int old_debug_level = debug_level;
    if (debug_level >= LOG_LVL_DEBUG)
        debug_level = LOG_LVL_INFO;
    bits_t bits = read_bits(target);
    debug_level = old_debug_level;
 
    if (bits.haltnot && bits.interrupt) {
        target->state = TARGET_DEBUG_RUNNING;
        LOG_DEBUG("debug running");
    } else if (bits.haltnot && !bits.interrupt) {
        if (target->state != TARGET_HALTED)
            return handle_halt(target, announce);
    } else if (!bits.haltnot && bits.interrupt) {
        /* Target is halting. There is no state for that, so don't change anything. */
        LOG_DEBUG("halting");
    } else if (!bits.haltnot && !bits.interrupt) {
        target->state = TARGET_RUNNING;
    }
 
    return ERROR_OK;
}
 
static int riscv011_poll(struct target *target)
{
    return poll_target(target, true);
}
 
static int riscv011_resume(struct target *target, int current,
        target_addr_t address, int handle_breakpoints, int debug_execution)
{
    RISCV_INFO(r);
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    r->prepped = false;
    return resume(target, debug_execution, false);
}
 
static int assert_reset(struct target *target)
{
    riscv011_info_t *info = get_info(target);
    /* TODO: Maybe what I implemented here is more like soft_reset_halt()? */
 
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    /* The only assumption we can make is that the TAP was reset. */
    if (wait_for_debugint_clear(target, true) != ERROR_OK) {
        LOG_ERROR("Debug interrupt didn't clear.");
        return ERROR_FAIL;
    }
 
    /* Not sure what we should do when there are multiple cores.
     * Here just reset the single hart we're talking to. */
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKM, riscv_ebreakm);
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKS, riscv_ebreaks);
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKU, riscv_ebreaku);
    info->dcsr = set_field(info->dcsr, DCSR_EBREAKH, 1);
    info->dcsr |= DCSR_HALT;
    if (target->reset_halt)
        info->dcsr |= DCSR_NDRESET;
    else
        info->dcsr |= DCSR_FULLRESET;
    dram_write32(target, 0, lw(S0, ZERO, DEBUG_RAM_START + 16), false);
    dram_write32(target, 1, csrw(S0, CSR_DCSR), false);
    /* We shouldn't actually need the jump because a reset should happen. */
    dram_write_jump(target, 2, false);
    dram_write32(target, 4, info->dcsr, true);
    cache_invalidate(target);
 
    target->state = TARGET_RESET;
 
    return ERROR_OK;
}
 
static int deassert_reset(struct target *target)
{
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
    if (target->reset_halt)
        return wait_for_state(target, TARGET_HALTED);
    else
        return wait_for_state(target, TARGET_RUNNING);
}
 
static int read_memory(struct target *target, target_addr_t address,
        uint32_t size, uint32_t count, uint8_t *buffer, uint32_t increment)
{
    if (increment != size) {
        LOG_ERROR("read_memory with custom increment not implemented");
        return ERROR_NOT_IMPLEMENTED;
    }
 
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    cache_set32(target, 0, lw(S0, ZERO, DEBUG_RAM_START + 16));
    switch (size) {
        case 1:
            cache_set32(target, 1, lb(S1, S0, 0));
            cache_set32(target, 2, sw(S1, ZERO, DEBUG_RAM_START + 16));
            break;
        case 2:
            cache_set32(target, 1, lh(S1, S0, 0));
            cache_set32(target, 2, sw(S1, ZERO, DEBUG_RAM_START + 16));
            break;
        case 4:
            cache_set32(target, 1, lw(S1, S0, 0));
            cache_set32(target, 2, sw(S1, ZERO, DEBUG_RAM_START + 16));
            break;
        default:
            LOG_ERROR("Unsupported size: %d", size);
            return ERROR_FAIL;
    }
    cache_set_jump(target, 3);
    cache_write(target, CACHE_NO_READ, false);
 
    riscv011_info_t *info = get_info(target);
    const unsigned int max_batch_size = 256;
    scans_t *scans = scans_new(target, max_batch_size);
    if (!scans)
        return ERROR_FAIL;
 
    uint32_t result_value = 0x777;
    uint32_t i = 0;
    while (i < count + 3) {
        unsigned int batch_size = MIN(count + 3 - i, max_batch_size);
        scans_reset(scans);
 
        for (unsigned int j = 0; j < batch_size; j++) {
            if (i + j == count) {
                /* Just insert a read so we can scan out the last value. */
                scans_add_read32(scans, 4, false);
            } else if (i + j >= count + 1) {
                /* And check for errors. */
                scans_add_read32(scans, info->dramsize-1, false);
            } else {
                /* Write the next address and set interrupt. */
                uint32_t offset = size * (i + j);
                scans_add_write32(scans, 4, address + offset, true);
            }
        }
 
        int retval = scans_execute(scans);
        if (retval != ERROR_OK) {
            LOG_ERROR("JTAG execute failed: %d", retval);
            goto error;
        }
 
        int dbus_busy = 0;
        int execute_busy = 0;
        for (unsigned int j = 0; j < batch_size; j++) {
            dbus_status_t status = scans_get_u32(scans, j, DBUS_OP_START,
                    DBUS_OP_SIZE);
            switch (status) {
                case DBUS_STATUS_SUCCESS:
                    break;
                case DBUS_STATUS_FAILED:
                    LOG_ERROR("Debug RAM write failed. Hardware error?");
                    goto error;
                case DBUS_STATUS_BUSY:
                    dbus_busy++;
                    break;
                default:
                    LOG_ERROR("Got invalid bus access status: %d", status);
                    return ERROR_FAIL;
            }
            uint64_t data = scans_get_u64(scans, j, DBUS_DATA_START,
                    DBUS_DATA_SIZE);
            if (data & DMCONTROL_INTERRUPT)
                execute_busy++;
            if (i + j == count + 2) {
                result_value = data;
            } else if (i + j > 1) {
                uint32_t offset = size * (i + j - 2);
                switch (size) {
                    case 1:
                        buffer[offset] = data;
                        break;
                    case 2:
                        buffer[offset] = data;
                        buffer[offset+1] = data >> 8;
                        break;
                    case 4:
                        buffer[offset] = data;
                        buffer[offset+1] = data >> 8;
                        buffer[offset+2] = data >> 16;
                        buffer[offset+3] = data >> 24;
                        break;
                }
            }
            LOG_DEBUG("j=%d status=%d data=%09" PRIx64, j, status, data);
        }
        if (dbus_busy)
            increase_dbus_busy_delay(target);
        if (execute_busy)
            increase_interrupt_high_delay(target);
        if (dbus_busy || execute_busy) {
            wait_for_debugint_clear(target, false);
 
            /* Retry. */
            LOG_INFO("Retrying memory read starting from 0x%" TARGET_PRIxADDR
                    " with more delays", address + size * i);
        } else {
            i += batch_size;
        }
    }
 
    if (result_value != 0) {
        LOG_USER("Core got an exception (0x%x) while reading from 0x%"
                TARGET_PRIxADDR, result_value, address + size * (count-1));
        if (count > 1) {
            LOG_USER("(It may have failed between 0x%" TARGET_PRIxADDR
                    " and 0x%" TARGET_PRIxADDR " as well, but we "
                    "didn't check then.)",
                    address, address + size * (count-2) + size - 1);
        }
        goto error;
    }
 
    scans_delete(scans);
    cache_clean(target);
    return ERROR_OK;
 
error:
    scans_delete(scans);
    cache_clean(target);
    return ERROR_FAIL;
}
 
static int setup_write_memory(struct target *target, uint32_t size)
{
    switch (size) {
        case 1:
            cache_set32(target, 0, lb(S0, ZERO, DEBUG_RAM_START + 16));
            cache_set32(target, 1, sb(S0, T0, 0));
            break;
        case 2:
            cache_set32(target, 0, lh(S0, ZERO, DEBUG_RAM_START + 16));
            cache_set32(target, 1, sh(S0, T0, 0));
            break;
        case 4:
            cache_set32(target, 0, lw(S0, ZERO, DEBUG_RAM_START + 16));
            cache_set32(target, 1, sw(S0, T0, 0));
            break;
        default:
            LOG_ERROR("Unsupported size: %d", size);
            return ERROR_FAIL;
    }
    cache_set32(target, 2, addi(T0, T0, size));
    cache_set_jump(target, 3);
    cache_write(target, 4, false);
 
    return ERROR_OK;
}
 
static int write_memory(struct target *target, target_addr_t address,
        uint32_t size, uint32_t count, const uint8_t *buffer)
{
    riscv011_info_t *info = get_info(target);
    jtag_add_ir_scan(target->tap, &select_dbus, TAP_IDLE);
 
    /* Set up the address. */
    cache_set_store(target, 0, T0, SLOT1);
    cache_set_load(target, 1, T0, SLOT0);
    cache_set_jump(target, 2);
    cache_set(target, SLOT0, address);
    if (cache_write(target, 5, true) != ERROR_OK)
        return ERROR_FAIL;
 
    uint64_t t0 = cache_get(target, SLOT1);
    LOG_DEBUG("t0 is 0x%" PRIx64, t0);
 
    if (setup_write_memory(target, size) != ERROR_OK)
        return ERROR_FAIL;
 
    const unsigned int max_batch_size = 256;
    scans_t *scans = scans_new(target, max_batch_size);
    if (!scans)
        return ERROR_FAIL;
 
    uint32_t result_value = 0x777;
    uint32_t i = 0;
    while (i < count + 2) {
        unsigned int batch_size = MIN(count + 2 - i, max_batch_size);
        scans_reset(scans);
 
        for (unsigned int j = 0; j < batch_size; j++) {
            if (i + j >= count) {
                /* Check for an exception. */
                scans_add_read32(scans, info->dramsize-1, false);
            } else {
                /* Write the next value and set interrupt. */
                uint32_t value;
                uint32_t offset = size * (i + j);
                switch (size) {
                    case 1:
                        value = buffer[offset];
                        break;
                    case 2:
                        value = buffer[offset] |
                            (buffer[offset+1] << 8);
                        break;
                    case 4:
                        value = buffer[offset] |
                            ((uint32_t) buffer[offset+1] << 8) |
                            ((uint32_t) buffer[offset+2] << 16) |
                            ((uint32_t) buffer[offset+3] << 24);
                        break;
                    default:
                        goto error;
                }
 
                scans_add_write32(scans, 4, value, true);
            }
        }
 
        int retval = scans_execute(scans);
        if (retval != ERROR_OK) {
            LOG_ERROR("JTAG execute failed: %d", retval);
            goto error;
        }
 
        int dbus_busy = 0;
        int execute_busy = 0;
        for (unsigned int j = 0; j < batch_size; j++) {
            dbus_status_t status = scans_get_u32(scans, j, DBUS_OP_START,
                    DBUS_OP_SIZE);
            switch (status) {
                case DBUS_STATUS_SUCCESS:
                    break;
                case DBUS_STATUS_FAILED:
                    LOG_ERROR("Debug RAM write failed. Hardware error?");
                    goto error;
                case DBUS_STATUS_BUSY:
                    dbus_busy++;
                    break;
                default:
                    LOG_ERROR("Got invalid bus access status: %d", status);
                    return ERROR_FAIL;
            }
            int interrupt = scans_get_u32(scans, j, DBUS_DATA_START + 33, 1);
            if (interrupt)
                execute_busy++;
            if (i + j == count + 1)
                result_value = scans_get_u32(scans, j, DBUS_DATA_START, 32);
        }
        if (dbus_busy)
            increase_dbus_busy_delay(target);
        if (execute_busy)
            increase_interrupt_high_delay(target);
        if (dbus_busy || execute_busy) {
            wait_for_debugint_clear(target, false);
 
            /* Retry.
             * Set t0 back to what it should have been at the beginning of this
             * batch. */
            LOG_INFO("Retrying memory write starting from 0x%" TARGET_PRIxADDR
                    " with more delays", address + size * i);
 
            cache_clean(target);
 
            if (write_gpr(target, T0, address + size * i) != ERROR_OK)
                goto error;
 
            if (setup_write_memory(target, size) != ERROR_OK)
                goto error;
        } else {
            i += batch_size;
        }
    }
 
    if (result_value != 0) {
        LOG_ERROR("Core got an exception (0x%x) while writing to 0x%"
                TARGET_PRIxADDR, result_value, address + size * (count-1));
        if (count > 1) {
            LOG_ERROR("(It may have failed between 0x%" TARGET_PRIxADDR
                    " and 0x%" TARGET_PRIxADDR " as well, but we "
                    "didn't check then.)",
                    address, address + size * (count-2) + size - 1);
        }
        goto error;
    }
 
    scans_delete(scans);
    cache_clean(target);
    return register_write(target, T0, t0);
 
error:
    scans_delete(scans);
    cache_clean(target);
    return ERROR_FAIL;
}
 
static int arch_state(struct target *target)
{
    return ERROR_OK;
}
 
static COMMAND_HELPER(riscv011_print_info, struct target *target)
{
    /* Abstract description. */
    riscv_print_info_line(CMD, "target", "memory.read_while_running8", 0);
    riscv_print_info_line(CMD, "target", "memory.write_while_running8", 0);
    riscv_print_info_line(CMD, "target", "memory.read_while_running16", 0);
    riscv_print_info_line(CMD, "target", "memory.write_while_running16", 0);
    riscv_print_info_line(CMD, "target", "memory.read_while_running32", 0);
    riscv_print_info_line(CMD, "target", "memory.write_while_running32", 0);
    riscv_print_info_line(CMD, "target", "memory.read_while_running64", 0);
    riscv_print_info_line(CMD, "target", "memory.write_while_running64", 0);
    riscv_print_info_line(CMD, "target", "memory.read_while_running128", 0);
    riscv_print_info_line(CMD, "target", "memory.write_while_running128", 0);
 
    uint32_t dminfo = dbus_read(target, DMINFO);
    riscv_print_info_line(CMD, "dm", "authenticated", get_field(dminfo, DMINFO_AUTHENTICATED));
 
    return 0;
}
 
static int wait_for_authbusy(struct target *target)
{
    time_t start = time(NULL);
    while (1) {
        uint32_t dminfo = dbus_read(target, DMINFO);
        if (!get_field(dminfo, DMINFO_AUTHBUSY))
            break;
        if (time(NULL) - start > riscv_command_timeout_sec) {
            LOG_ERROR("Timed out after %ds waiting for authbusy to go low (dminfo=0x%x). "
                    "Increase the timeout with riscv set_command_timeout_sec.",
                    riscv_command_timeout_sec,
                    dminfo);
            return ERROR_FAIL;
        }
    }
 
    return ERROR_OK;
}
 
static int riscv011_authdata_read(struct target *target, uint32_t *value, unsigned int index)
{
    if (index > 1) {
        LOG_ERROR("Spec 0.11 only has a two authdata registers.");
        return ERROR_FAIL;
    }
 
    if (wait_for_authbusy(target) != ERROR_OK)
        return ERROR_FAIL;
 
    uint16_t authdata_address = index ? DMAUTHDATA1 : DMAUTHDATA0;
    *value = dbus_read(target, authdata_address);
 
    return ERROR_OK;
}
 
static int riscv011_authdata_write(struct target *target, uint32_t value, unsigned int index)
{
    if (index > 1) {
        LOG_ERROR("Spec 0.11 only has a two authdata registers.");
        return ERROR_FAIL;
    }
 
    if (wait_for_authbusy(target) != ERROR_OK)
        return ERROR_FAIL;
 
    uint16_t authdata_address = index ? DMAUTHDATA1 : DMAUTHDATA0;
    dbus_write(target, authdata_address, value);
 
    return ERROR_OK;
}
 
static int init_target(struct command_context *cmd_ctx,
        struct target *target)
{
    LOG_DEBUG("init");
    RISCV_INFO(generic_info);
    generic_info->get_register = get_register;
    generic_info->set_register = set_register;
    generic_info->read_memory = read_memory;
    generic_info->authdata_read = &riscv011_authdata_read;
    generic_info->authdata_write = &riscv011_authdata_write;
    generic_info->print_info = &riscv011_print_info;
 
    generic_info->version_specific = calloc(1, sizeof(riscv011_info_t));
    if (!generic_info->version_specific)
        return ERROR_FAIL;
 
    /* Assume 32-bit until we discover the real value in examine(). */
    generic_info->xlen = 32;
    riscv_init_registers(target);
 
    return ERROR_OK;
}
 
struct target_type riscv011_target = {
    .name = "riscv",
 
    .init_target = init_target,
    .deinit_target = deinit_target,
    .examine = examine,
 
    /* poll current target status */
    .poll = riscv011_poll,
 
    .halt = halt,
    .resume = riscv011_resume,
    .step = step,
 
    .assert_reset = assert_reset,
    .deassert_reset = deassert_reset,
 
    .write_memory = write_memory,
 
    .arch_state = arch_state,
};