2 * slcand.c - userspace daemon for serial line CAN interface driver SLCAN
4 * Copyright (c) 2009 Robert Haddon <robert.haddon@verari.com>
5 * Copyright (c) 2009 Verari Systems Inc.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * Send feedback to <linux-can@vger.kernel.org>
29 #include <sys/types.h>
36 #include <sys/ioctl.h>
40 /* default slcan line discipline since Kernel 2.6.25 */
41 #define LDISC_N_SLCAN 17
43 /* Change this to whatever your daemon is called */
44 #define DAEMON_NAME "slcand"
46 /* Change this to the user under which to run */
47 #define RUN_AS_USER "root"
49 /* The length of ttypath buffer */
50 #define TTYPATH_LENGTH 64
52 #define EXIT_SUCCESS 0
53 #define EXIT_FAILURE 1
55 /* UART flow control types */
60 void print_usage(char *prg)
62 fprintf(stderr, "\nUsage: %s [options] <tty> [canif-name]\n\n", prg);
63 fprintf(stderr, "Options: -o (send open command 'O\\r')\n");
64 fprintf(stderr, " -c (send close command 'C\\r')\n");
65 fprintf(stderr, " -f (read status flags with 'F\\r' to reset error states)\n");
66 fprintf(stderr, " -s <speed> (set CAN speed 0..8)\n");
67 fprintf(stderr, " -S <speed> (set UART speed in baud)\n");
68 fprintf(stderr, " -t <type> (set UART flow control type 'hw' or 'sw')\n");
69 fprintf(stderr, " -b <btr> (set bit time register value)\n");
70 fprintf(stderr, " -F (stay in foreground; no daemonize)\n");
71 fprintf(stderr, " -h (show this help page)\n");
72 fprintf(stderr, "\nExamples:\n");
73 fprintf(stderr, "slcand -o -c -f -s6 ttyslcan0\n");
74 fprintf(stderr, "slcand -o -c -f -s6 ttyslcan0 can0\n");
75 fprintf(stderr, "\n");
79 static int slcand_running;
81 static char ttypath[TTYPATH_LENGTH];
83 static void child_handler(int signum)
93 syslog(LOG_NOTICE, "received signal %i on %s", signum, ttypath);
94 exit_code = EXIT_FAILURE;
99 syslog(LOG_NOTICE, "received signal %i on %s", signum, ttypath);
100 exit_code = EXIT_SUCCESS;
106 static int look_up_uart_speed(long int s)
163 int main(int argc, char *argv[])
166 char const *devprefix = "/dev/";
168 char buf[IFNAMSIZ+1];
176 int send_read_status_flags = 0;
178 char *uart_speed_str = NULL;
179 long int uart_speed = 0;
180 int flow_type = FLOW_NONE;
182 int run_as_daemon = 1;
184 int ldisc = LDISC_N_SLCAN;
189 while ((opt = getopt(argc, argv, "ocfs:S:t:b:?hF")) != -1) {
198 send_read_status_flags = 1;
202 if (strlen(speed) > 1)
203 print_usage(argv[0]);
206 uart_speed_str = optarg;
208 uart_speed = strtol(uart_speed_str, NULL, 10);
210 print_usage(argv[0]);
211 if (look_up_uart_speed(uart_speed) == -1) {
212 fprintf(stderr, "Unsupported UART speed (%lu)\n", uart_speed);
217 if (!strcmp(optarg, "hw")) {
219 } else if (!strcmp(optarg, "sw")) {
222 fprintf(stderr, "Unsupported flow type (%s)\n", optarg);
229 print_usage(argv[0]);
237 print_usage(argv[0]);
242 /* Initialize the logging interface */
243 openlog(DAEMON_NAME, LOG_PID, LOG_LOCAL5);
245 /* Parse serial device name and optional can interface name */
248 print_usage(argv[0]);
250 name = argv[optind + 1];
252 /* Prepare the tty device name string */
253 pch = strstr(tty, devprefix);
255 snprintf(ttypath, TTYPATH_LENGTH, "%s%s", devprefix, tty);
257 snprintf(ttypath, TTYPATH_LENGTH, "%s", tty);
259 syslog(LOG_INFO, "starting on TTY device %s", ttypath);
264 syslog(LOG_ERR, "failed to daemonize");
269 /* Trap signals that we expect to receive */
270 signal(SIGINT, child_handler);
271 signal(SIGTERM, child_handler);
277 /* Now we are a daemon -- do the work for which we were paid */
278 fd = open(ttypath, O_RDWR | O_NONBLOCK | O_NOCTTY);
280 syslog(LOG_NOTICE, "failed to open TTY device %s\n", ttypath);
285 /* Configure baud rate */
286 memset(&tios, 0, sizeof(struct termios));
287 if (tcgetattr(fd, &tios) < 0) {
288 syslog(LOG_NOTICE, "failed to get attributes for TTY device %s: %s\n", ttypath, strerror(errno));
292 /* Get old values for later restore */
293 old_ispeed = cfgetispeed(&tios);
294 old_ospeed = cfgetospeed(&tios);
296 /* Reset UART settings */
298 tios.c_iflag &= ~IXOFF;
299 tios.c_cflag &= ~CRTSCTS;
302 cfsetispeed(&tios, look_up_uart_speed(uart_speed));
303 cfsetospeed(&tios, look_up_uart_speed(uart_speed));
306 if (flow_type == FLOW_HW)
307 tios.c_cflag |= CRTSCTS;
308 else if (flow_type == FLOW_SW)
309 tios.c_iflag |= (IXON | IXOFF);
312 if (tcsetattr(fd, TCSADRAIN, &tios) < 0)
313 syslog(LOG_NOTICE, "Cannot set attributes for device \"%s\": %s!\n", ttypath, strerror(errno));
316 sprintf(buf, "C\rS%s\r", speed);
317 write(fd, buf, strlen(buf));
321 sprintf(buf, "C\rs%s\r", btr);
322 write(fd, buf, strlen(buf));
325 if (send_read_status_flags) {
327 write(fd, buf, strlen(buf));
332 write(fd, buf, strlen(buf));
335 /* set slcan like discipline on given tty */
336 if (ioctl(fd, TIOCSETD, &ldisc) < 0) {
337 perror("ioctl TIOCSETD");
341 /* retrieve the name of the created CAN netdevice */
342 if (ioctl(fd, SIOCGIFNAME, buf) < 0) {
343 perror("ioctl SIOCGIFNAME");
347 syslog(LOG_NOTICE, "attached TTY %s to netdevice %s\n", ttypath, buf);
349 /* try to rename the created netdevice */
352 int s = socket(PF_INET, SOCK_DGRAM, 0);
355 perror("socket for interface rename");
357 strncpy(ifr.ifr_name, buf, IFNAMSIZ);
358 strncpy(ifr.ifr_newname, name, IFNAMSIZ);
360 if (ioctl(s, SIOCSIFNAME, &ifr) < 0) {
361 syslog(LOG_NOTICE, "netdevice %s rename to %s failed\n", buf, name);
362 perror("ioctl SIOCSIFNAME rename");
365 syslog(LOG_NOTICE, "netdevice %s renamed to %s\n", buf, name);
372 while (slcand_running)
373 sleep(1); /* wait 1 second */
375 /* Reset line discipline */
376 syslog(LOG_INFO, "stopping on TTY device %s", ttypath);
378 if (ioctl(fd, TIOCSETD, &ldisc) < 0) {
379 perror("ioctl TIOCSETD");
385 write(fd, buf, strlen(buf));
388 /* Reset old rates */
389 cfsetispeed(&tios, old_ispeed);
390 cfsetospeed(&tios, old_ospeed);
393 if (tcsetattr(fd, TCSADRAIN, &tios) < 0)
394 syslog(LOG_NOTICE, "Cannot set attributes for device \"%s\": %s!\n", ttypath, strerror(errno));
397 syslog(LOG_NOTICE, "terminated on %s", ttypath);