path: root/meta-facebook/meta-wedge/recipes-wedge/rackmon/rackmon/modbus.c

/*
 * Copyright 2014-present Facebook. All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <time.h>
#include "modbus.h"
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sched.h>
#include <pthread.h>

int verbose = 0;

#define TIOCSERWAITTEMT 0x5499
int waitfd(int fd) {
  int loops = 0;
  ioctl(fd, TIOCSERWAITTEMT, DEFAULT_GPIO);
  while(1) {
    int lsr;
    int ret = ioctl(fd, TIOCSERGETLSR, &lsr);
    if(ret == -1) {
      fprintf(stderr, "Error checking ioctl: %s\n", strerror(errno));
      break;
    }
    if(lsr & TIOCSER_TEMT) break;
    // never should hit this with new ioctl
    loops++;
  }
  return loops;
}

void gpio_on(int fd) {
  lseek(fd, 0, SEEK_SET);
  write(fd, "1", 1);
}

void gpio_off(int fd) {
  lseek(fd, 0, SEEK_SET);
  write(fd, "0", 1);
}

void decode_hex_in_place(char* buf, size_t* len) {
    for(int i = 0; i < *len; i+=2) {
      sscanf(buf + i, "%2hhx", buf + (i / 2));
    }
    *len = *len / 2;
}

void append_modbus_crc16(char* buf, size_t* len) {
  uint16_t crc = modbus_crc16(buf, *len);
  dbg("[*] Append Modbus CRC16 %04x\n", crc);
  buf[(*len)++] = crc >> 8;
  buf[(*len)++] = crc & 0x00FF;
}

void print_hex(FILE* f, char* buf, size_t len) {
  for(int i = 0; i < len; i++)
    fprintf(f, "%02x ", buf[i]);
}

size_t read_wait(int fd, char* dst, size_t maxlen, int mdelay_us) {
  fd_set fdset;
  struct timeval timeout;
  char read_buf[16];
  size_t read_size = 0;
  size_t pos = 0;
  memset(dst, 0, maxlen);
  while(pos < maxlen) {
    FD_ZERO(&fdset);
    FD_SET(fd, &fdset);
    timeout.tv_sec = 0;
    timeout.tv_usec = mdelay_us;
    int rv = select(fd + 1, &fdset, NULL, NULL, &timeout);
    if(rv == -1) {
      perror("select()");
    } else if (rv == 0) {
      break;
    }
    read_size = read(fd, read_buf, 16);
    if(read_size < 0) {
      if(errno == EAGAIN) continue;
      fprintf(stderr, "read error: %s\n", strerror(errno));
      exit(1);
    }
    if((pos + read_size) <= maxlen) {
      memcpy(dst + pos, read_buf, read_size);
      pos += read_size;
    } else {
      return pos;
      fprintf(stderr, "Response buffer overflowed!\n");
    }
  }
  return pos;
}

/* From libmodbus, https://github.com/stephane/libmodbus
 * Under LGPL. */
/* Table of CRC values for high-order byte */
static const uint8_t table_crc_hi[] = {
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
};

/* Table of CRC values for low-order byte */
static const uint8_t table_crc_lo[] = {
    0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
    0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
    0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
    0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
    0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
    0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
    0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
    0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
    0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
    0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
    0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
    0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
    0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
    0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
    0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
    0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
    0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
    0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
    0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
    0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
    0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
    0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
    0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
    0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
    0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
    0x43, 0x83, 0x41, 0x81, 0x80, 0x40
};

uint16_t modbus_crc16(char* buffer, size_t buffer_length) {
    uint8_t crc_hi = 0xFF; /* high CRC byte initialized */
    uint8_t crc_lo = 0xFF; /* low CRC byte initialized */
    unsigned int i; /* will index into CRC lookup */

    /* pass through message buffer */
    while (buffer_length--) {
      i = crc_hi ^ *((uint8_t*)(buffer++)); /* calculate the CRC  */
      crc_hi = crc_lo ^ table_crc_hi[i];
      crc_lo = table_crc_lo[i];
    }

    return (crc_hi << 8 | crc_lo);
}


double ts_diff (struct timespec* begin, struct timespec* end) {
  return 1000.0 * (end->tv_sec) + (1e-6 * end->tv_nsec)
    - (1000.0 * (begin->tv_sec) + (1e-6 * begin->tv_nsec));
}

static long success = 0;
static long crcfail = 0;
static long timeout = 0;
static long stat_wait = 0;

int modbuscmd(modbus_req *req) {
    int error = 0;
    struct termios tio;
    char modbus_cmd[req->cmd_len + 2];
    size_t cmd_len = req->cmd_len;

    if (verbose)
      fprintf(stderr, "[*] Setting TTY flags!\n");
    memset(&tio, 0, sizeof(tio));
    // CREAD should be left *off* until we've confirmed THRE
    // to avoid catching false character starts
    cfsetspeed(&tio,B19200);
    tio.c_cflag |= PARENB;
    tio.c_cflag |= CLOCAL;
    tio.c_cflag |= CS8;
    tio.c_iflag |= INPCK;
    tio.c_cc[VMIN] = 1;
    tio.c_cc[VTIME] = 0;
    CHECK(tcsetattr(req->tty_fd,TCSANOW,&tio));

    memcpy(modbus_cmd, req->modbus_cmd, cmd_len);
    append_modbus_crc16(modbus_cmd, &cmd_len);

    // print command as sent
    if (verbose)  {
      fprintf(stderr, "Will send:  ");
      print_hex(stderr, modbus_cmd, cmd_len);
      fprintf(stderr, "\n");
    }

    dbg("[*] Writing!\n");

    // hoped adding the ioctl to do the switching would have alleviated the
    // need to do SCHED_FIFO, but we still get preempted between the write and
    // ioctl syscalls w/o it often enough to break f/w updates.
    struct sched_param sp;
    sp.sched_priority = 50;
    int policy = SCHED_FIFO;
    CHECKP(sched, pthread_setschedparam(pthread_self(), policy, &sp));
    // gpio on, write, wait, gpio off
    gpio_on(req->gpio_fd);
    struct timespec write_begin;
    struct timespec wait_begin;
    struct timespec wait_end;
    struct timespec read_end;
    clock_gettime(CLOCK_MONOTONIC_RAW, &write_begin);
    write(req->tty_fd, modbus_cmd, cmd_len);
    clock_gettime(CLOCK_MONOTONIC_RAW, &wait_begin);
    int waitloops = waitfd(req->tty_fd);
    clock_gettime(CLOCK_MONOTONIC_RAW, &wait_end);
    gpio_off(req->gpio_fd);
    sp.sched_priority = 0;
    // Enable UART read
    tio.c_cflag |= CREAD;
    CHECK(tcsetattr(req->tty_fd,TCSANOW,&tio));
    policy = SCHED_OTHER;
    CHECKP(sched, pthread_setschedparam(pthread_self(), policy, &sp));

    dbg("[*] waitfd loops: %d\n", waitloops);
    dbg("[*] reading any response...\n");
    // Read back response
    size_t mb_pos = 0;
    memset(req->dest_buf, 0, req->dest_limit);
    if(req->expected_len == 0) {
      req->expected_len = req->dest_limit;
    }
    if(req->expected_len > req->dest_limit) {
      return -1;
    }
    mb_pos = read_wait(req->tty_fd, req->dest_buf, req->expected_len, req->timeout);
    clock_gettime(CLOCK_MONOTONIC_RAW, &read_end);
    req->dest_len = mb_pos;
    if(mb_pos >= 4) {
      uint16_t crc = modbus_crc16(req->dest_buf, mb_pos - 2);
      dbg("Modbus response CRC: %04X\n ", crc);
      if((req->dest_buf[mb_pos - 2] == (crc >> 8)) &&
          (req->dest_buf[mb_pos - 1] == (crc & 0x00FF))) {
        dbg("CRC OK!\n");
      } else {
        dbg("BAD CRC :(\n");
        fprintf(stderr, "bad crc timings:");
        fprintf(stderr, "  write: %.2f ms", ts_diff(&write_begin, &wait_begin));
        fprintf(stderr, "  wait: %.2f ms", ts_diff(&wait_begin, &wait_end));
        fprintf(stderr, "  read: %.2f ms\n", ts_diff(&wait_end, &read_end));
        if(!req->scan) {
          crcfail++;
        }
        if(verbose) {
          print_hex(stderr, req->dest_buf, mb_pos);
        }
        return MODBUS_BAD_CRC;
      }
    } else {
      fprintf(stderr, "timeout timings:");
      fprintf(stderr, "  write: %.2f ms", ts_diff(&write_begin, &wait_begin));
      fprintf(stderr, "  wait: %.2f ms", ts_diff(&wait_begin, &wait_end));
      fprintf(stderr, "  wait: %d iters", waitloops);
      fprintf(stderr, "  read: %.2f ms\n", ts_diff(&wait_end, &read_end));
      dbg("No response :(\n");
      if(!req->scan) {
        timeout++;
      }
      return MODBUS_RESPONSE_TIMEOUT;
    }

cleanup:
    if(error != 0) {
      error = -1;
      fprintf(stderr, "%s\n", strerror(errno));
    } else {
      //fprintf(stderr, "success, timings:");
      //fprintf(stderr, "  write: %.2f ms", ts_diff(&write_begin, &wait_begin));
      //fprintf(stderr, "  wait: %.2f ms", ts_diff(&wait_begin, &wait_end));
      //fprintf(stderr, "  read: %.2f ms -- ", ts_diff(&wait_end, &read_end));
      if(stat_wait == 0 && !req->scan) {
        fprintf(stderr, "success: %.2f%%  crcfail %.2f%%, timeout %.2f%%\n",
            ((double) 100.0 * success / (success + crcfail + timeout)),
            ((double) 100.0 * crcfail / (success + crcfail + timeout)),
            ((double) 100.0 * timeout / (success + crcfail + timeout)));
        stat_wait = 1000;
        fprintf(stderr, "success timings:");
        fprintf(stderr, "  write: %.2f ms", ts_diff(&write_begin, &wait_begin));
        fprintf(stderr, "  wait: %.2f ms", ts_diff(&wait_begin, &wait_end));
        fprintf(stderr, "  wait: %d iters", waitloops);
        fprintf(stderr, "  read: %.2f ms\n", ts_diff(&wait_end, &read_end));
      } else if (!req->scan) {
        stat_wait--;
      }
      if(!req->scan) {
        success++;
      }
    }
    return 0;
}

const char* modbus_strerror(int mb_err) {
  if (mb_err < 0) {
    mb_err = -mb_err;
  }
  switch(mb_err) {
    case 4:
      return "timed out";
    case 5:
      return "crc check failed";
    default:
      return "unknown";
  }
}