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bacnet_stack/ports/linux/rs485.c
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/**************************************************************************
*
* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
* Updated by Nikola Jelic 2011 <nikola.jelic@euroicc.com>
*
* SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0
*
*********************************************************************/
/** @file linux/rs485.c Provides Linux-specific functions for RS-485 serial. */
/* The module handles sending data out the RS-485 port */
/* and handles receiving data from the RS-485 port. */
/* Customize this file for your specific hardware */
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Linux includes */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sched.h>
#include <sys/ioctl.h>
/* for scandir */
#include <dirent.h>
/* for basename */
#include <libgen.h>
/* Local includes */
#include "bacnet/datalink/mstp.h"
#include "rs485.h"
#include "bacnet/basic/sys/fifo.h"
#include "bacnet/basic/sys/debug.h"
#include <sys/select.h>
#include <sys/time.h>
#include "dlmstp_port.h"
/* Posix serial programming reference:
http://www.easysw.com/~mike/serial/serial.html */
/* Use ionice wrapper to improve serial performance:
$ sudo ionice -c 1 -n 0 ./bin/bacserv 12345
*/
/* handle returned from open() */
static int RS485_Handle = -1;
/* baudrate */
static unsigned int RS485_Baud = 38400;
/* serial port name, /dev/ttyS0,
/dev/ttyUSB0 for USB->RS485 from B&B Electronics USOPTL4 */
static char *RS485_Port_Name = "/dev/ttyUSB0";
/* some terminal I/O have RS-485 specific functionality */
#ifndef RS485MOD
#define RS485MOD 0
#endif
/* serial I/O settings */
static struct termios2 RS485_oldtio2;
/* Ring buffer for incoming bytes, in order to speed up the receiving. */
static FIFO_BUFFER Rx_FIFO;
/* buffer size needs to be a power of 2 */
static uint8_t Rx_Buffer[4096];
/*********************************************************************
* DESCRIPTION: Configures the interface name
* RETURN: none
* ALGORITHM: none
* NOTES: none
*********************************************************************/
void RS485_Set_Interface(char *ifname)
{
/* note: expects a constant char, or char from the heap */
if (ifname) {
RS485_Port_Name = ifname;
}
}
/*********************************************************************
* DESCRIPTION: Returns the interface name
* RETURN: none
* ALGORITHM: none
* NOTES: none
*********************************************************************/
const char *RS485_Interface(void)
{
return RS485_Port_Name;
}
/****************************************************************************
* DESCRIPTION: Returns the baud rate that we are currently running at
* RETURN: none
* ALGORITHM: none
* NOTES: none
*****************************************************************************/
uint32_t RS485_Get_Baud_Rate(void)
{
return RS485_Baud;
}
/****************************************************************************
* DESCRIPTION: Returns the baud rate that we are currently running at
* RETURN: none
* ALGORITHM: none
* NOTES: none
*****************************************************************************/
uint32_t RS485_Get_Port_Baud_Rate(struct mstp_port_struct_t *mstp_port)
{
SHARED_MSTP_DATA *poSharedData = (SHARED_MSTP_DATA *)mstp_port->UserData;
if (!poSharedData) {
return 0;
}
return poSharedData->RS485_Baud;
}
/****************************************************************************
* DESCRIPTION: Sets the baud rate for the chip USART
* RETURN: none
* ALGORITHM: none
* NOTES: none
*****************************************************************************/
bool RS485_Set_Baud_Rate(uint32_t baud)
{
struct termios2 newtio;
RS485_Baud = baud;
if (RS485_Handle >= 0) {
/* clear struct for new port settings */
memset(&newtio, 0, sizeof(newtio));
/*
BOTHER: Set bps rate.
https://man7.org/linux/man-pages/man2/TCSETS.2const.html
CRTSCTS : output hardware flow control (only used if the cable has
all necessary lines. See sect. 7 of Serial-HOWTO)
CS8 : 8n1 (8bit,no parity,1 stopbit)
CLOCAL : local connection, no modem control
CREAD : enable receiving characters
*/
newtio.c_cflag =
CS8 | CLOCAL | CREAD | RS485MOD | BOTHER | (BOTHER << IBSHIFT);
newtio.c_ispeed = RS485_Baud;
newtio.c_ospeed = RS485_Baud;
/* Raw input */
newtio.c_iflag = 0;
/* Raw output */
newtio.c_oflag = 0;
/* no processing */
newtio.c_lflag = 0;
/* activate the settings for the port after flushing I/O */
termios2_tcsetattr(RS485_Handle, TCSAFLUSH, &newtio);
#if PRINT_ENABLED
debug_fprintf(stdout, "RS485 Baud Rate %u\n", RS485_Baud);
fflush(stdout);
#endif
}
return true;
}
/****************************************************************************
* DESCRIPTION: Gets RS485 config (e.g. automatic RTS for half-duplex direction)
* RETURN: true on success
* ALGORITHM: none
* NOTES: https://www.kernel.org/doc/Documentation/serial/serial-rs485.txt
*****************************************************************************/
bool RS485_Get_Config(struct serial_rs485 *config)
{
return ioctl(RS485_Handle, TIOCGRS485, config) == 0;
}
/****************************************************************************
* DESCRIPTION: Sets RS485 config (e.g. automatic RTS for half-duplex direction)
* RETURN: true on success
* ALGORITHM: none
* NOTES: https://www.kernel.org/doc/Documentation/serial/serial-rs485.txt
*****************************************************************************/
bool RS485_Set_Config(const struct serial_rs485 *const config)
{
return ioctl(RS485_Handle, TIOCSRS485, config) == 0;
}
/****************************************************************************
* DESCRIPTION: Transmit a frame on the wire
* RETURN: none
* ALGORITHM: none
* NOTES: none
*****************************************************************************/
void RS485_Send_Frame(
struct mstp_port_struct_t *mstp_port, /* port specific data */
const uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
uint16_t nbytes /* number of bytes of data (up to 501) */)
{
uint32_t turnaround_time_usec = Tturnaround * 1000000UL;
uint32_t baud = RS485_Baud;
int handle = RS485_Handle;
ssize_t written = 0;
int greska;
const SHARED_MSTP_DATA *poSharedData = NULL;
if (mstp_port && mstp_port->UserData) {
poSharedData = (SHARED_MSTP_DATA *)mstp_port->UserData;
/* poSharedData->RS485_Baud stores a termios B-constant (e.g.
* B38400=15), NOT the actual numeric baud rate. Using it directly in
* the turnaround delay formula (40,000,000 / baud) would produce ~2.7
* seconds instead of the correct ~1ms at 38400 baud. dlmstp_baud_rate()
* converts the termios constant to the real value.
*/
baud = dlmstp_baud_rate(mstp_port);
handle = poSharedData->RS485_Handle;
}
/* sleeping for turnaround time is necessary to give other devices
time to change from sending to receiving state. */
usleep(turnaround_time_usec / baud);
/*
On success, the number of bytes written are returned (zero
indicates nothing was written). On error, -1 is returned, and
errno is set appropriately. If count is zero and the file
descriptor refers to a regular file, 0 will be returned without
causing any other effect. For a special file, the results are not
portable.
*/
written = write(handle, buffer, nbytes);
greska = errno;
if (written <= 0) {
printf("write error: %s\n", strerror(greska));
} else {
/* wait until all output has been transmitted. */
termios2_tcdrain(handle);
}
/* per MSTP spec, sort of */
if (mstp_port) {
mstp_port->SilenceTimerReset((void *)mstp_port);
}
}
/****************************************************************************
* DESCRIPTION: Get a byte of receive data
* RETURN: none
* ALGORITHM: none
* NOTES: none
*****************************************************************************/
void RS485_Check_UART_Data(struct mstp_port_struct_t *mstp_port)
{
fd_set input;
struct timeval waiter;
uint8_t buf[2048];
ssize_t n;
int handle = RS485_Handle;
SHARED_MSTP_DATA *poSharedData;
FIFO_BUFFER *fifo = &Rx_FIFO;
waiter.tv_sec = 0;
waiter.tv_usec = 5000;
poSharedData = (SHARED_MSTP_DATA *)mstp_port->UserData;
if (poSharedData) {
handle = poSharedData->RS485_Handle;
fifo = &poSharedData->Rx_FIFO;
}
if (mstp_port->ReceiveError == true) {
/* do nothing but wait for state machine to clear the error */
} else if (mstp_port->DataAvailable == false) {
/* wait for state machine to read from the DataRegister */
if (FIFO_Count(fifo) > 0) {
/* data is available */
mstp_port->DataRegister = FIFO_Get(fifo);
mstp_port->DataAvailable = true;
/* FIFO is giving data - just poll */
waiter.tv_sec = 0;
waiter.tv_usec = 0;
}
}
/* grab bytes and stuff them into the FIFO every time */
FD_ZERO(&input);
FD_SET(handle, &input);
n = select(handle + 1, &input, NULL, NULL, &waiter);
if (n < 0) {
return;
}
if (FD_ISSET(handle, &input)) {
n = read(handle, buf, sizeof(buf));
if (n > 0) {
FIFO_Add(fifo, &buf[0], n);
}
}
}
void RS485_Cleanup(void)
{
/* restore the old port settings */
termios2_tcsetattr(RS485_Handle, TCSANOW, &RS485_oldtio2);
close(RS485_Handle);
}
void RS485_Initialize(void)
{
#if PRINT_ENABLED
debug_printf("RS485 Interface: %s\n", RS485_Port_Name);
#endif
/*
Open device for reading and writing.
Blocking mode - more CPU effecient
*/
RS485_Handle = open(RS485_Port_Name, O_RDWR | O_NOCTTY /*| O_NDELAY */);
if (RS485_Handle < 0) {
perror(RS485_Port_Name);
exit(-1);
}
#if 0
/* non blocking for the read */
fcntl(RS485_Handle, F_SETFL, FNDELAY);
#else
/* efficient blocking for the read */
fcntl(RS485_Handle, F_SETFL, 0);
#endif
/* save current serial port settings */
termios2_tcgetattr(RS485_Handle, &RS485_oldtio2);
RS485_Set_Baud_Rate(RS485_Baud);
/* destructor */
atexit(RS485_Cleanup);
/* flush any data waiting */
usleep(200000);
termios2_tcflush(RS485_Handle, TCIOFLUSH);
/* ringbuffer */
FIFO_Init(&Rx_FIFO, Rx_Buffer, sizeof(Rx_Buffer));
}
/* Print in a format for Wireshark ExtCap */
void RS485_Print_Ports(void)
{
int n;
struct dirent **namelist;
const char *sysdir = "/sys/class/tty/";
struct stat st;
char buffer[1024];
char device_dir[1024];
char *driver_name = NULL;
int fd = 0;
bool valid_port = false;
struct serial_struct serinfo;
/* Scan through /sys/class/tty -
it contains all tty-devices in the system */
n = scandir(sysdir, &namelist, NULL, NULL);
if (n < 0) {
perror("RS485: scandir");
} else {
while (n--) {
if (strcmp(namelist[n]->d_name, "..") &&
strcmp(namelist[n]->d_name, ".")) {
snprintf(
device_dir, sizeof(device_dir), "%s%s/device", sysdir,
namelist[n]->d_name);
/* Stat the devicedir and handle it if it is a symlink */
if (lstat(device_dir, &st) == 0 && S_ISLNK(st.st_mode)) {
memset(buffer, 0, sizeof(buffer));
snprintf(
device_dir, sizeof(device_dir), "%s%s/device/driver",
sysdir, namelist[n]->d_name);
if (readlink(device_dir, buffer, sizeof(buffer)) > 0) {
valid_port = false;
driver_name = basename(buffer);
if (strcmp(driver_name, "serial8250") == 0) {
/* serial8250-devices must be probed */
snprintf(
device_dir, sizeof(device_dir), "/dev/%s",
namelist[n]->d_name);
fd = open(
device_dir, O_RDWR | O_NONBLOCK | O_NOCTTY);
if (fd >= 0) {
/* Get serial_info */
if (ioctl(fd, TIOCGSERIAL, &serinfo) == 0) {
/* If device type is not PORT_UNKNOWN */
/* we accept the port */
if (serinfo.type != PORT_UNKNOWN) {
valid_port = true;
}
}
close(fd);
}
} else {
valid_port = true;
}
if (valid_port) {
/* print full absolute file path */
printf(
"interface {value=/dev/%s}"
"{display=MS/TP Capture on /dev/%s}\n",
namelist[n]->d_name, namelist[n]->d_name);
}
}
}
}
free(namelist[n]);
}
free(namelist);
}
}
int termios2_tcsetattr(
const int fildes,
int optional_actions,
const struct termios2 *const termios2_p)
{
/* https://man7.org/linux/man-pages/man2/TCSETS.2const.html */
switch (optional_actions) {
case TCSANOW:
optional_actions = TCSETS2;
break;
case TCSADRAIN:
optional_actions = TCSETSW2;
break;
case TCSAFLUSH:
optional_actions = TCSETSF2;
break;
default:
errno = EINVAL;
return -1;
};
return ioctl(fildes, optional_actions, termios2_p);
}
int termios2_tcgetattr(const int fildes, struct termios2 *termios2_p)
{
/* https://man7.org/linux/man-pages/man2/TCSETS.2const.html */
return ioctl(fildes, TCGETS2, termios2_p);
}
int termios2_tcflush(const int fildes, const int queue_selector)
{
/* https://manpages.opensuse.org/Tumbleweed/man-pages/TCFLSH.2const.en.html
*/
return ioctl(fildes, TCFLSH, queue_selector);
}
int termios2_tcdrain(const int fildes)
{
/*
https://man7.org/linux/man-pages/man2/TCSBRK.2const.html
TCSBRK Equivalent to tcsendbreak(fd, arg).
Linux treats tcsendbreak(fd,arg) with nonzero arg like tcdrain(fd)
*/
return ioctl(fildes, TCSBRK, 1);
}
#ifdef TEST_RS485
#include <string.h>
int main(int argc, char *argv[])
{
struct mstp_port_struct_t mstp_port = { 0 };
uint8_t token_buf[8] = { 0x55, 0xFF, 0x00, 0x7E, 0x07, 0x00, 0x00, 0xFD };
uint8_t pfm_buf[8] = { 0x55, 0xFF, 0x01, 0x67, 0x07, 0x00, 0x00, 0x3E };
long baud = 38400;
bool write_token = false;
bool write_pfm = false;
/* argv has the "/dev/ttyS0" or some other device */
if (argc > 1) {
RS485_Set_Interface(argv[1]);
}
if (argc > 2) {
baud = strtol(argv[2], NULL, 0);
}
if (argc > 3) {
if (strcmp("token", argv[3]) == 0) {
write_token = true;
}
if (strcmp("pfm", argv[3]) == 0) {
write_pfm = true;
}
}
RS485_Set_Baud_Rate(baud);
RS485_Initialize();
for (;;) {
if (write_token) {
RS485_Send_Frame(NULL, token_buf, sizeof(token_buf));
usleep(25000);
} else if (write_pfm) {
RS485_Send_Frame(NULL, pfm_buf, sizeof(pfm_buf));
usleep(100000);
} else {
RS485_Check_UART_Data(&mstp_port);
if (mstp_port.DataAvailable) {
fprintf(stderr, "%02X ", mstp_port.DataRegister);
mstp_port.DataAvailable = false;
}
}
}
return 0;
}
#endif
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