remote_bitbang.c

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// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 *   Copyright (C) 2011 by Richard Uhler                                   *
 *   ruhler@mit.edu                                                        *
 *                                                                         *
 *   Copyright (C) 2021 by Manuel Wick <manuel@matronix.de>                *
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#ifndef _WIN32
#include <sys/un.h>
#include <netdb.h>
#include <netinet/tcp.h>
#endif
#include "helper/system.h"
#include "helper/replacements.h"
#include <jtag/interface.h>
#include "bitbang.h"
 
/* arbitrary limit on host name length: */
#define REMOTE_BITBANG_HOST_MAX 255
 
static char *remote_bitbang_host;
static char *remote_bitbang_port;
 
static int remote_bitbang_fd;
static uint8_t remote_bitbang_send_buf[512];
static unsigned int remote_bitbang_send_buf_used;
 
static bool use_remote_sleep;
 
/* Circular buffer. When start == end, the buffer is empty. */
static char remote_bitbang_recv_buf[256];
static unsigned int remote_bitbang_recv_buf_start;
static unsigned int remote_bitbang_recv_buf_end;
 
static bool remote_bitbang_recv_buf_full(void)
{
    return remote_bitbang_recv_buf_end ==
        ((remote_bitbang_recv_buf_start + sizeof(remote_bitbang_recv_buf) - 1) %
         sizeof(remote_bitbang_recv_buf));
}
 
static bool remote_bitbang_recv_buf_empty(void)
{
    return remote_bitbang_recv_buf_start == remote_bitbang_recv_buf_end;
}
 
static unsigned int remote_bitbang_recv_buf_contiguous_available_space(void)
{
    if (remote_bitbang_recv_buf_end >= remote_bitbang_recv_buf_start) {
        unsigned int space = sizeof(remote_bitbang_recv_buf) -
                     remote_bitbang_recv_buf_end;
        if (remote_bitbang_recv_buf_start == 0)
            space -= 1;
        return space;
    } else {
        return remote_bitbang_recv_buf_start -
               remote_bitbang_recv_buf_end - 1;
    }
}
 
static int remote_bitbang_flush(void)
{
    if (remote_bitbang_send_buf_used <= 0)
        return ERROR_OK;
 
    unsigned int offset = 0;
    while (offset < remote_bitbang_send_buf_used) {
        ssize_t written = write_socket(remote_bitbang_fd, remote_bitbang_send_buf + offset,
                                       remote_bitbang_send_buf_used - offset);
        if (written < 0) {
            log_socket_error("remote_bitbang_putc");
            remote_bitbang_send_buf_used = 0;
            return ERROR_FAIL;
        }
        offset += written;
    }
    remote_bitbang_send_buf_used = 0;
    return ERROR_OK;
}
 
enum block_bool {
    NO_BLOCK,
    BLOCK
};
 
/* Read any incoming data, placing it into the buffer. */
static int remote_bitbang_fill_buf(enum block_bool block)
{
    if (remote_bitbang_recv_buf_empty()) {
        /* If the buffer is empty, reset it to 0 so we get more
         * contiguous space. */
        remote_bitbang_recv_buf_start = 0;
        remote_bitbang_recv_buf_end = 0;
    }
 
    if (block == BLOCK) {
        if (remote_bitbang_flush() != ERROR_OK)
            return ERROR_FAIL;
        socket_block(remote_bitbang_fd);
    }
 
    bool first = true;
    while (!remote_bitbang_recv_buf_full()) {
        unsigned int contiguous_available_space =
                remote_bitbang_recv_buf_contiguous_available_space();
        ssize_t count = read_socket(remote_bitbang_fd,
                remote_bitbang_recv_buf + remote_bitbang_recv_buf_end,
                contiguous_available_space);
        if (first && block == BLOCK)
            socket_nonblock(remote_bitbang_fd);
        if (count > 0) {
            remote_bitbang_recv_buf_end += count;
            if (remote_bitbang_recv_buf_end == sizeof(remote_bitbang_recv_buf))
                remote_bitbang_recv_buf_end = 0;
        } else if (count == 0) {
            /* When read_socket returns 0, socket reached EOF and there is
             * no data to read. But if request was blocking, the caller
             * expected some data. Such situations should be treated as ERROR. */
            if (first && block == BLOCK) {
                LOG_ERROR("remote_bitbang: socket closed by remote");
                return ERROR_FAIL;
            }
            return ERROR_OK;
        } else if (count < 0) {
#ifdef _WIN32
            if (WSAGetLastError() == WSAEWOULDBLOCK) {
#else
            if (errno == EAGAIN) {
#endif
                return ERROR_OK;
            } else {
                log_socket_error("remote_bitbang_fill_buf");
                return ERROR_FAIL;
            }
        }
        first = false;
    }
 
    return ERROR_OK;
}
 
typedef enum {
    NO_FLUSH,
    FLUSH_SEND_BUF
} flush_bool_t;
 
static int remote_bitbang_queue(int c, flush_bool_t flush)
{
    remote_bitbang_send_buf[remote_bitbang_send_buf_used++] = c;
    if (flush == FLUSH_SEND_BUF ||
            remote_bitbang_send_buf_used >= ARRAY_SIZE(remote_bitbang_send_buf))
        return remote_bitbang_flush();
    return ERROR_OK;
}
 
static int remote_bitbang_quit(void)
{
    if (remote_bitbang_queue('Q', FLUSH_SEND_BUF) == ERROR_FAIL)
        return ERROR_FAIL;
 
    if (close_socket(remote_bitbang_fd) != 0) {
        log_socket_error("close_socket");
        return ERROR_FAIL;
    }
 
    free(remote_bitbang_host);
    free(remote_bitbang_port);
 
    LOG_INFO("remote_bitbang interface quit");
    return ERROR_OK;
}
 
static bb_value_t char_to_int(int c)
{
    switch (c) {
        case '0':
            return BB_LOW;
        case '1':
            return BB_HIGH;
        default:
            remote_bitbang_quit();
            LOG_ERROR("remote_bitbang: invalid read response: %c(%i)", c, c);
            return BB_ERROR;
    }
}
 
static int remote_bitbang_sample(void)
{
    if (remote_bitbang_fill_buf(NO_BLOCK) != ERROR_OK)
        return ERROR_FAIL;
    assert(!remote_bitbang_recv_buf_full());
    return remote_bitbang_queue('R', NO_FLUSH);
}
 
static bb_value_t remote_bitbang_read_sample(void)
{
    if (remote_bitbang_recv_buf_empty()) {
        if (remote_bitbang_fill_buf(BLOCK) != ERROR_OK)
            return BB_ERROR;
    }
    assert(!remote_bitbang_recv_buf_empty());
    int c = remote_bitbang_recv_buf[remote_bitbang_recv_buf_start];
    remote_bitbang_recv_buf_start =
        (remote_bitbang_recv_buf_start + 1) % sizeof(remote_bitbang_recv_buf);
    return char_to_int(c);
}
 
static int remote_bitbang_write(int tck, int tms, int tdi)
{
    char c = '0' + ((tck ? 0x4 : 0x0) | (tms ? 0x2 : 0x0) | (tdi ? 0x1 : 0x0));
    return remote_bitbang_queue(c, NO_FLUSH);
}
 
static int remote_bitbang_reset(int trst, int srst)
{
    char c = 'r' + ((trst ? 0x2 : 0x0) | (srst ? 0x1 : 0x0));
    /* Always flush the send buffer on reset, because the reset call need not be
     * followed by jtag_execute_queue(). */
    return remote_bitbang_queue(c, FLUSH_SEND_BUF);
}
 
static int remote_bitbang_sleep(unsigned int microseconds)
{
    if (!use_remote_sleep) {
        jtag_sleep(microseconds);
        return ERROR_OK;
    }
 
    int tmp;
    unsigned int ms = microseconds / 1000;
    unsigned int us = microseconds % 1000;
 
    for (unsigned int i = 0; i < ms; i++) {
        tmp = remote_bitbang_queue('Z', NO_FLUSH);
        if (tmp != ERROR_OK)
            return tmp;
    }
 
    for (unsigned int i = 0; i < us; i++) {
        tmp = remote_bitbang_queue('z', NO_FLUSH);
        if (tmp != ERROR_OK)
            return tmp;
    }
 
    return remote_bitbang_flush();
}
 
static int remote_bitbang_blink(bool on)
{
    char c = on ? 'B' : 'b';
    return remote_bitbang_queue(c, FLUSH_SEND_BUF);
}
 
static void remote_bitbang_swdio_drive(bool is_output)
{
    char c = is_output ? 'O' : 'o';
    if (remote_bitbang_queue(c, FLUSH_SEND_BUF) == ERROR_FAIL)
        LOG_ERROR("Error setting direction for swdio");
}
 
static int remote_bitbang_swdio_read(void)
{
    if (remote_bitbang_queue('c', FLUSH_SEND_BUF) != ERROR_FAIL)
        return remote_bitbang_read_sample();
    else
        return BB_ERROR;
}
 
static int remote_bitbang_swd_write(int swclk, int swdio)
{
    char c = 'd' + ((swclk ? 0x2 : 0x0) | (swdio ? 0x1 : 0x0));
    return remote_bitbang_queue(c, NO_FLUSH);
}
 
static struct bitbang_interface remote_bitbang_bitbang = {
    .buf_size = sizeof(remote_bitbang_recv_buf) - 1,
    .sample = &remote_bitbang_sample,
    .read_sample = &remote_bitbang_read_sample,
    .write = &remote_bitbang_write,
    .swdio_read = &remote_bitbang_swdio_read,
    .swdio_drive = &remote_bitbang_swdio_drive,
    .swd_write = &remote_bitbang_swd_write,
    .blink = &remote_bitbang_blink,
    .sleep = &remote_bitbang_sleep,
    .flush = &remote_bitbang_flush,
};
 
static int remote_bitbang_init_tcp(void)
{
    struct addrinfo hints = { .ai_family = AF_UNSPEC, .ai_socktype = SOCK_STREAM };
    struct addrinfo *result, *rp;
    int fd = 0;
 
    LOG_INFO("Connecting to %s:%s",
            remote_bitbang_host ? remote_bitbang_host : "localhost",
            remote_bitbang_port);
 
    /* Obtain address(es) matching host/port */
    int s = getaddrinfo(remote_bitbang_host, remote_bitbang_port, &hints, &result);
    if (s != 0) {
        LOG_ERROR("getaddrinfo: %s\n", gai_strerror(s));
        return ERROR_FAIL;
    }
 
    /* getaddrinfo() returns a list of address structures.
     Try each address until we successfully connect(2).
     If socket(2) (or connect(2)) fails, we (close the socket
     and) try the next address. */
 
    for (rp = result; rp ; rp = rp->ai_next) {
        fd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
        if (fd == -1)
            continue;
 
        if (connect(fd, rp->ai_addr, rp->ai_addrlen) != -1)
            break; /* Success */
 
        close(fd);
    }
 
    /* We work hard to collapse the writes into the minimum number, so when
     * we write something we want to get it to the other end of the
     * connection as fast as possible. */
    int one = 1;
    /* On Windows optval has to be a const char *. */
    setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (const char *)&one, sizeof(one));
 
    freeaddrinfo(result); /* No longer needed */
 
    if (!rp) { /* No address succeeded */
        log_socket_error("Failed to connect");
        return ERROR_FAIL;
    }
 
    return fd;
}
 
static int remote_bitbang_init_unix(void)
{
    if (!remote_bitbang_host) {
        LOG_ERROR("host/socket not specified");
        return ERROR_FAIL;
    }
 
    LOG_INFO("Connecting to unix socket %s", remote_bitbang_host);
    int fd = socket(PF_UNIX, SOCK_STREAM, 0);
    if (fd < 0) {
        log_socket_error("socket");
        return ERROR_FAIL;
    }
 
    struct sockaddr_un addr;
    addr.sun_family = AF_UNIX;
    strncpy(addr.sun_path, remote_bitbang_host, sizeof(addr.sun_path));
    addr.sun_path[sizeof(addr.sun_path)-1] = '\0';
 
    if (connect(fd, (struct sockaddr *)&addr, sizeof(struct sockaddr_un)) < 0) {
        log_socket_error("connect");
        return ERROR_FAIL;
    }
 
    return fd;
}
 
static int remote_bitbang_init(void)
{
    bitbang_interface = &remote_bitbang_bitbang;
 
    remote_bitbang_recv_buf_start = 0;
    remote_bitbang_recv_buf_end = 0;
 
    LOG_INFO("Initializing remote_bitbang driver");
    if (!remote_bitbang_port)
        remote_bitbang_fd = remote_bitbang_init_unix();
    else
        remote_bitbang_fd = remote_bitbang_init_tcp();
 
    if (remote_bitbang_fd < 0)
        return remote_bitbang_fd;
 
    socket_nonblock(remote_bitbang_fd);
 
    LOG_INFO("remote_bitbang driver initialized");
    return ERROR_OK;
}
 
COMMAND_HANDLER(remote_bitbang_handle_remote_bitbang_port_command)
{
    if (CMD_ARGC == 1) {
        uint16_t port;
        COMMAND_PARSE_NUMBER(u16, CMD_ARGV[0], port);
        free(remote_bitbang_port);
        remote_bitbang_port = port == 0 ? NULL : strdup(CMD_ARGV[0]);
        return ERROR_OK;
    }
    return ERROR_COMMAND_SYNTAX_ERROR;
}
 
COMMAND_HANDLER(remote_bitbang_handle_remote_bitbang_host_command)
{
    if (CMD_ARGC == 1) {
        free(remote_bitbang_host);
        remote_bitbang_host = strdup(CMD_ARGV[0]);
        return ERROR_OK;
    }
    return ERROR_COMMAND_SYNTAX_ERROR;
}
 
static const char * const remote_bitbang_transports[] = { "jtag", "swd", NULL };
 
COMMAND_HANDLER(remote_bitbang_handle_remote_bitbang_use_remote_sleep_command)
{
    if (CMD_ARGC != 1)
        return ERROR_COMMAND_SYNTAX_ERROR;
 
    COMMAND_PARSE_ON_OFF(CMD_ARGV[0], use_remote_sleep);
 
    return ERROR_OK;
}
 
static const struct command_registration remote_bitbang_subcommand_handlers[] = {
    {
        .name = "port",
        .handler = remote_bitbang_handle_remote_bitbang_port_command,
        .mode = COMMAND_CONFIG,
        .help = "Set the port to use to connect to the remote jtag.\n"
            "  if 0 or unset, use unix sockets to connect to the remote jtag.",
        .usage = "port_number",
    },
    {
        .name = "host",
        .handler = remote_bitbang_handle_remote_bitbang_host_command,
        .mode = COMMAND_CONFIG,
        .help = "Set the host to use to connect to the remote jtag.\n"
            "  if port is 0 or unset, this is the name of the unix socket to use.",
        .usage = "host_name",
    },
    {
        .name = "use_remote_sleep",
        .handler = remote_bitbang_handle_remote_bitbang_use_remote_sleep_command,
        .mode = COMMAND_CONFIG,
        .help = "Rather than executing sleep locally, include delays in the "
            "instruction stream for the remote host.",
        .usage = "(on|off)",
    },
    COMMAND_REGISTRATION_DONE
};
 
static const struct command_registration remote_bitbang_command_handlers[] = {
    {
        .name = "remote_bitbang",
        .mode = COMMAND_ANY,
        .help = "perform remote_bitbang management",
        .chain = remote_bitbang_subcommand_handlers,
        .usage = "",
    },
    COMMAND_REGISTRATION_DONE
};
 
static int remote_bitbang_execute_queue(struct jtag_command *cmd_queue)
{
    /* safety: the send buffer must be empty, no leftover characters from
     * previous transactions */
    assert(remote_bitbang_send_buf_used == 0);
 
    /* process the JTAG command queue */
    int ret = bitbang_execute_queue(cmd_queue);
    if (ret != ERROR_OK)
        return ret;
 
    /* flush not-yet-sent characters, if any */
    return remote_bitbang_flush();
}
 
static struct jtag_interface remote_bitbang_interface = {
    .execute_queue = &remote_bitbang_execute_queue,
};
 
struct adapter_driver remote_bitbang_adapter_driver = {
    .name = "remote_bitbang",
    .transports = remote_bitbang_transports,
    .commands = remote_bitbang_command_handlers,
 
    .init = &remote_bitbang_init,
    .quit = &remote_bitbang_quit,
    .reset = &remote_bitbang_reset,
 
    .jtag_ops = &remote_bitbang_interface,
    .swd_ops = &bitbang_swd,
};