esirisc_jtag.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 *   Copyright (C) 2018 by Square, Inc.                                    *
 *   Steven Stallion <stallion@squareup.com>                               *
 *   James Zhao <hjz@squareup.com>                                         *
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <helper/binarybuffer.h>
#include <helper/log.h>
#include <helper/types.h>
#include <jtag/jtag.h>
#include <jtag/commands.h>
#include <jtag/interface.h>
 
#include "esirisc_jtag.h"
 
static uint8_t esirisc_jtag_get_eid(struct esirisc_jtag *jtag_info);
 
static void esirisc_jtag_set_instr(struct esirisc_jtag *jtag_info, uint32_t new_instr)
{
    struct jtag_tap *tap = jtag_info->tap;
 
    if (buf_get_u32(tap->cur_instr, 0, tap->ir_length) != new_instr) {
        struct scan_field field;
        uint8_t t[4] = { 0 };
 
        field.num_bits = tap->ir_length;
        field.out_value = t;
        buf_set_u32(t, 0, field.num_bits, new_instr);
        field.in_value = NULL;
 
        jtag_add_ir_scan(tap, &field, TAP_IDLE);
    }
}
 
/*
 * The data register is latched every 8 bits while in the Shift-DR state
 * (Update-DR is not supported). This necessitates prepending padding
 * bits to ensure data is aligned when multiple TAPs are present.
 */
static int esirisc_jtag_get_padding(void)
{
    int padding = 0;
    int bypass_devices = 0;
 
    for (struct jtag_tap *tap = jtag_tap_next_enabled(NULL); tap;
            tap = jtag_tap_next_enabled(tap))
        if (tap->bypass)
            bypass_devices++;
 
    int num_bits = bypass_devices % 8;
    if (num_bits > 0)
        padding = 8 - num_bits;
 
    return padding;
}
 
static int esirisc_jtag_count_bits(unsigned int num_fields,
        struct scan_field *fields)
{
    int bit_count = 0;
 
    for (unsigned int i = 0; i < num_fields; ++i)
        bit_count += fields[i].num_bits;
 
    return bit_count;
}
 
/*
 * Data received from the target will be byte-stuffed if it contains
 * either the pad byte (0xAA) or stuffing marker (0x55). Buffers should
 * be sized twice the expected length to account for stuffing overhead.
 */
static void esirisc_jtag_unstuff(uint8_t *data, size_t len)
{
    uint8_t *r, *w;
    uint8_t *end;
 
    r = w = data;
    end = data + len;
    while (r < end) {
        if (*r == STUFF_MARKER) {
            r++; /* skip stuffing marker */
            assert(r < end);
            *w++ = *r++ ^ STUFF_MARKER;
        } else
            *w++ = *r++;
    }
}
 
/*
 * The eSi-Debug protocol defines a byte-oriented command/response
 * channel that operates over serial or JTAG. While not strictly
 * required, separate DR scans are used for sending and receiving data.
 * This allows the TAP to recover gracefully if the byte stream is
 * corrupted at the expense of sending additional padding bits.
 */
 
static int esirisc_jtag_send(struct esirisc_jtag *jtag_info, uint8_t command,
        int num_out_fields, struct scan_field *out_fields)
{
    int num_fields = 2 + num_out_fields;
    struct scan_field *fields = cmd_queue_alloc(num_fields * sizeof(struct scan_field));
 
    esirisc_jtag_set_instr(jtag_info, INSTR_DEBUG);
 
    fields[0].num_bits = esirisc_jtag_get_padding();
    fields[0].out_value = NULL;
    fields[0].in_value = NULL;
 
    fields[1].num_bits = 8;
    fields[1].out_value = &command;
    fields[1].in_value = NULL;
 
    /* append command data */
    for (int i = 0; i < num_out_fields; ++i)
        jtag_scan_field_clone(&fields[2+i], &out_fields[i]);
 
    jtag_add_dr_scan(jtag_info->tap, num_fields, fields, TAP_IDLE);
 
    return jtag_execute_queue();
}
 
static int esirisc_jtag_recv(struct esirisc_jtag *jtag_info,
        int num_in_fields, struct scan_field *in_fields)
{
    int num_in_bits = esirisc_jtag_count_bits(num_in_fields, in_fields);
    int num_in_bytes = DIV_ROUND_UP(num_in_bits, 8);
 
    struct scan_field fields[3];
    /* prevent zero-size variable length array */
    int r_size = num_in_bytes ? num_in_bytes * 2 : 1;
    uint8_t r[r_size];
 
    esirisc_jtag_set_instr(jtag_info, INSTR_DEBUG);
 
    fields[0].num_bits = esirisc_jtag_get_padding() + 1;
    fields[0].out_value = NULL;
    fields[0].in_value = NULL;
 
    fields[1].num_bits = 8;
    fields[1].out_value = NULL;
    fields[1].in_value = &jtag_info->status;
 
    fields[2].num_bits = num_in_bits * 2;
    fields[2].out_value = NULL;
    fields[2].in_value = r;
 
    jtag_add_dr_scan(jtag_info->tap, ARRAY_SIZE(fields), fields, TAP_IDLE);
 
    int retval = jtag_execute_queue();
    if (retval != ERROR_OK)
        return retval;
 
    /* unstuff response data and write back to caller */
    if (num_in_fields > 0) {
        esirisc_jtag_unstuff(r, ARRAY_SIZE(r));
 
        int bit_count = 0;
        for (int i = 0; i < num_in_fields; ++i) {
            buf_set_buf(r, bit_count, in_fields[i].in_value, 0, in_fields[i].num_bits);
            bit_count += in_fields[i].num_bits;
        }
    }
 
    return ERROR_OK;
}
 
static int esirisc_jtag_check_status(struct esirisc_jtag *jtag_info)
{
    uint8_t eid = esirisc_jtag_get_eid(jtag_info);
    if (eid != EID_NONE) {
        LOG_ERROR("esirisc_jtag: bad status: 0x%02" PRIx8 " (DA: %" PRId32 ", "
                "S: %" PRId32 ", EID: 0x%02" PRIx8 ")",
                jtag_info->status, esirisc_jtag_is_debug_active(jtag_info),
                esirisc_jtag_is_stopped(jtag_info), eid);
        return ERROR_FAIL;
    }
 
    return ERROR_OK;
}
 
static int esirisc_jtag_send_and_recv(struct esirisc_jtag *jtag_info, uint8_t command,
        int num_out_fields, struct scan_field *out_fields,
        int num_in_fields, struct scan_field *in_fields)
{
    int retval;
 
    jtag_info->status = 0;  /* clear status */
 
    retval = esirisc_jtag_send(jtag_info, command, num_out_fields, out_fields);
    if (retval != ERROR_OK) {
        LOG_ERROR("esirisc_jtag: send failed (command: 0x%02" PRIx8 ")", command);
        return ERROR_FAIL;
    }
 
    retval = esirisc_jtag_recv(jtag_info, num_in_fields, in_fields);
    if (retval != ERROR_OK) {
        LOG_ERROR("esirisc_jtag: recv failed (command: 0x%02" PRIx8 ")", command);
        return ERROR_FAIL;
    }
 
    return esirisc_jtag_check_status(jtag_info);
}
 
/*
 * Status is automatically updated after each command completes;
 * these functions make each field available to the caller.
 */
 
bool esirisc_jtag_is_debug_active(struct esirisc_jtag *jtag_info)
{
    return !!(jtag_info->status & 1<<7);    /* DA */
}
 
bool esirisc_jtag_is_stopped(struct esirisc_jtag *jtag_info)
{
    return !!(jtag_info->status & 1<<6);    /* S */
}
 
static uint8_t esirisc_jtag_get_eid(struct esirisc_jtag *jtag_info)
{
    return jtag_info->status & 0x3f;        /* EID */
}
 
/*
 * Most commands manipulate target data (eg. memory and registers); each
 * command returns a status byte that indicates success. Commands must
 * transmit multibyte values in big-endian order, however response
 * values are in little-endian order. Target endianness does not have an
 * effect on this ordering.
 */
 
int esirisc_jtag_read_byte(struct esirisc_jtag *jtag_info, uint32_t address, uint8_t *data)
{
    struct scan_field out_fields[1];
    uint8_t a[4];
 
    out_fields[0].num_bits = 32;
    out_fields[0].out_value = a;
    h_u32_to_be(a, address);
    out_fields[0].in_value = NULL;
 
    struct scan_field in_fields[1];
    uint8_t d[1];
 
    in_fields[0].num_bits = 8;
    in_fields[0].out_value = NULL;
    in_fields[0].in_value = d;
 
    int retval = esirisc_jtag_send_and_recv(jtag_info, DEBUG_READ_BYTE,
            ARRAY_SIZE(out_fields), out_fields, ARRAY_SIZE(in_fields), in_fields);
    if (retval != ERROR_OK)
        return retval;
 
    *data = *d;
    LOG_DEBUG("address: 0x%" PRIx32 ", data: 0x%" PRIx8, address, *data);
 
    return ERROR_OK;
}
 
int esirisc_jtag_read_hword(struct esirisc_jtag *jtag_info, uint32_t address, uint16_t *data)
{
    struct scan_field out_fields[1];
    uint8_t a[4];
 
    out_fields[0].num_bits = 32;
    out_fields[0].out_value = a;
    h_u32_to_be(a, address);
    out_fields[0].in_value = NULL;
 
    struct scan_field in_fields[1];
    uint8_t d[2];
 
    in_fields[0].num_bits = 16;
    in_fields[0].out_value = NULL;
    in_fields[0].in_value = d;
 
    int retval = esirisc_jtag_send_and_recv(jtag_info, DEBUG_READ_HWORD,
            ARRAY_SIZE(out_fields), out_fields, ARRAY_SIZE(in_fields), in_fields);
    if (retval != ERROR_OK)
        return retval;
 
    *data = le_to_h_u16(d);
    LOG_DEBUG("address: 0x%" PRIx32 ", data: 0x%" PRIx16, address, *data);
 
    return ERROR_OK;
}
 
int esirisc_jtag_read_word(struct esirisc_jtag *jtag_info, uint32_t address, uint32_t *data)
{
    struct scan_field out_fields[1];
    uint8_t a[4];
 
    out_fields[0].num_bits = 32;
    out_fields[0].out_value = a;
    h_u32_to_be(a, address);
    out_fields[0].in_value = NULL;
 
    struct scan_field in_fields[1];
    uint8_t d[4];
 
    in_fields[0].num_bits = 32;
    in_fields[0].out_value = NULL;
    in_fields[0].in_value = d;
 
    int retval = esirisc_jtag_send_and_recv(jtag_info, DEBUG_READ_WORD,
            ARRAY_SIZE(out_fields), out_fields, ARRAY_SIZE(in_fields), in_fields);
    if (retval != ERROR_OK)
        return retval;
 
    *data = le_to_h_u32(d);
    LOG_DEBUG("address: 0x%" PRIx32 ", data: 0x%" PRIx32, address, *data);
 
    return ERROR_OK;
}
 
int esirisc_jtag_write_byte(struct esirisc_jtag *jtag_info, uint32_t address, uint8_t data)
{
    struct scan_field out_fields[2];
    uint8_t a[4];
 
    LOG_DEBUG("address: 0x%" PRIx32 ", data: 0x%" PRIx8, address, data);
 
    out_fields[0].num_bits = 32;
    out_fields[0].out_value = a;
    h_u32_to_be(a, address);
    out_fields[0].in_value = NULL;
 
    out_fields[1].num_bits = 8;
    out_fields[1].out_value = &data;
    out_fields[1].in_value = NULL;
 
    return esirisc_jtag_send_and_recv(jtag_info, DEBUG_WRITE_BYTE,
            ARRAY_SIZE(out_fields), out_fields, 0, NULL);
}
 
int esirisc_jtag_write_hword(struct esirisc_jtag *jtag_info, uint32_t address, uint16_t data)
{
    struct scan_field out_fields[2];
    uint8_t a[4], d[2];
 
    LOG_DEBUG("address: 0x%" PRIx32 ", data: 0x%" PRIx16, address, data);
 
    out_fields[0].num_bits = 32;
    out_fields[0].out_value = a;
    h_u32_to_be(a, address);
    out_fields[0].in_value = NULL;
 
    out_fields[1].num_bits = 16;
    out_fields[1].out_value = d;
    h_u16_to_be(d, data);
    out_fields[1].in_value = NULL;
 
    return esirisc_jtag_send_and_recv(jtag_info, DEBUG_WRITE_HWORD,
            ARRAY_SIZE(out_fields), out_fields, 0, NULL);
}
 
int esirisc_jtag_write_word(struct esirisc_jtag *jtag_info, uint32_t address, uint32_t data)
{
    struct scan_field out_fields[2];
    uint8_t a[4], d[4];
 
    LOG_DEBUG("address: 0x%" PRIx32 ", data: 0x%" PRIx32, address, data);
 
    out_fields[0].num_bits = 32;
    out_fields[0].out_value = a;
    h_u32_to_be(a, address);
    out_fields[0].in_value = NULL;
 
    out_fields[1].num_bits = 32;
    out_fields[1].out_value = d;
    h_u32_to_be(d, data);
    out_fields[1].in_value = NULL;
 
    return esirisc_jtag_send_and_recv(jtag_info, DEBUG_WRITE_WORD,
            ARRAY_SIZE(out_fields), out_fields, 0, NULL);
}
 
int esirisc_jtag_read_reg(struct esirisc_jtag *jtag_info, uint8_t reg, uint32_t *data)
{
    struct scan_field out_fields[1];
 
    out_fields[0].num_bits = 8;
    out_fields[0].out_value = &reg;
    out_fields[0].in_value = NULL;
 
    struct scan_field in_fields[1];
    uint8_t d[4];
 
    in_fields[0].num_bits = 32;
    in_fields[0].out_value = NULL;
    in_fields[0].in_value = d;
 
    int retval = esirisc_jtag_send_and_recv(jtag_info, DEBUG_READ_REG,
            ARRAY_SIZE(out_fields), out_fields, ARRAY_SIZE(in_fields), in_fields);
    if (retval != ERROR_OK)
        return retval;
 
    *data = le_to_h_u32(d);
    LOG_DEBUG("register: 0x%" PRIx8 ", data: 0x%" PRIx32, reg, *data);
 
    return ERROR_OK;
}
 
int esirisc_jtag_write_reg(struct esirisc_jtag *jtag_info, uint8_t reg, uint32_t data)
{
    struct scan_field out_fields[2];
    uint8_t d[4];
 
    LOG_DEBUG("register: 0x%" PRIx8 ", data: 0x%" PRIx32, reg, data);
 
    out_fields[0].num_bits = 8;
    out_fields[0].out_value = &reg;
    out_fields[0].in_value = NULL;
 
    out_fields[1].num_bits = 32;
    out_fields[1].out_value = d;
    h_u32_to_be(d, data);
    out_fields[1].in_value = NULL;
 
    return esirisc_jtag_send_and_recv(jtag_info, DEBUG_WRITE_REG,
            ARRAY_SIZE(out_fields), out_fields, 0, NULL);
}
 
int esirisc_jtag_read_csr(struct esirisc_jtag *jtag_info, uint8_t bank, uint8_t csr, uint32_t *data)
{
    struct scan_field out_fields[1];
    uint8_t c[2];
 
    out_fields[0].num_bits = 16;
    out_fields[0].out_value = c;
    h_u16_to_be(c, (csr << 5) | bank);
    out_fields[0].in_value = NULL;
 
    struct scan_field in_fields[1];
    uint8_t d[4];
 
    in_fields[0].num_bits = 32;
    in_fields[0].out_value = NULL;
    in_fields[0].in_value = d;
 
    int retval = esirisc_jtag_send_and_recv(jtag_info, DEBUG_READ_CSR,
            ARRAY_SIZE(out_fields), out_fields, ARRAY_SIZE(in_fields), in_fields);
    if (retval != ERROR_OK)
        return retval;
 
    *data = le_to_h_u32(d);
    LOG_DEBUG("bank: 0x%" PRIx8 ", csr: 0x%" PRIx8 ", data: 0x%" PRIx32, bank, csr, *data);
 
    return ERROR_OK;
}
 
int esirisc_jtag_write_csr(struct esirisc_jtag *jtag_info, uint8_t bank, uint8_t csr, uint32_t data)
{
    struct scan_field out_fields[2];
    uint8_t c[2], d[4];
 
    LOG_DEBUG("bank: 0x%" PRIx8 ", csr: 0x%" PRIx8 ", data: 0x%" PRIx32, bank, csr, data);
 
    out_fields[0].num_bits = 16;
    out_fields[0].out_value = c;
    h_u16_to_be(c, (csr << 5) | bank);
    out_fields[0].in_value = NULL;
 
    out_fields[1].num_bits = 32;
    out_fields[1].out_value = d;
    h_u32_to_be(d, data);
    out_fields[1].in_value = NULL;
 
    return esirisc_jtag_send_and_recv(jtag_info, DEBUG_WRITE_CSR,
            ARRAY_SIZE(out_fields), out_fields, 0, NULL);
}
 
/*
 * Control commands affect CPU operation; these commands send no data
 * and return a status byte.
 */
 
static inline int esirisc_jtag_send_ctrl(struct esirisc_jtag *jtag_info, uint8_t command)
{
    return esirisc_jtag_send_and_recv(jtag_info, command, 0, NULL, 0, NULL);
}
 
int esirisc_jtag_enable_debug(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_ENABLE_DEBUG);
}
 
static __attribute__((unused)) int esirisc_jtag_disable_debug(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_DISABLE_DEBUG);
}
 
int esirisc_jtag_assert_reset(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_ASSERT_RESET);
}
 
int esirisc_jtag_deassert_reset(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_DEASSERT_RESET);
}
 
int esirisc_jtag_break(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_BREAK);
}
 
int esirisc_jtag_continue(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_CONTINUE);
}
 
int esirisc_jtag_flush_caches(struct esirisc_jtag *jtag_info)
{
    return esirisc_jtag_send_ctrl(jtag_info, DEBUG_FLUSH_CACHES);
}