1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * PTP 1588 clock support - User space test program
4  *
5  * Copyright (C) 2010 OMICRON electronics GmbH
6  */
7 #define _GNU_SOURCE
8 #define __SANE_USERSPACE_TYPES__        /* For PPC64, to get LL64 types */
9 #include <errno.h>
10 #include <fcntl.h>
11 #include <inttypes.h>
12 #include <math.h>
13 #include <signal.h>
14 #include <stdio.h>
15 #include <stdlib.h>
16 #include <string.h>
17 #include <sys/ioctl.h>
18 #include <sys/mman.h>
19 #include <sys/stat.h>
20 #include <sys/time.h>
21 #include <sys/timex.h>
22 #include <sys/types.h>
23 #include <time.h>
24 #include <unistd.h>
25 
26 #include <linux/ptp_clock.h>
27 
28 #define DEVICE "/dev/ptp0"
29 
30 #ifndef ADJ_SETOFFSET
31 #define ADJ_SETOFFSET 0x0100
32 #endif
33 
34 #ifndef CLOCK_INVALID
35 #define CLOCK_INVALID -1
36 #endif
37 
38 #define NSEC_PER_SEC 1000000000LL
39 
40 /* clock_adjtime is not available in GLIBC < 2.14 */
41 #if !__GLIBC_PREREQ(2, 14)
42 #include <sys/syscall.h>
clock_adjtime(clockid_t id,struct timex * tx)43 static int clock_adjtime(clockid_t id, struct timex *tx)
44 {
45 	return syscall(__NR_clock_adjtime, id, tx);
46 }
47 #endif
48 
show_flag_test(int rq_index,unsigned int flags,int err)49 static void show_flag_test(int rq_index, unsigned int flags, int err)
50 {
51 	printf("PTP_EXTTS_REQUEST%c flags 0x%08x : (%d) %s\n",
52 	       rq_index ? '1' + rq_index : ' ',
53 	       flags, err, strerror(errno));
54 	/* sigh, uClibc ... */
55 	errno = 0;
56 }
57 
do_flag_test(int fd,unsigned int index)58 static void do_flag_test(int fd, unsigned int index)
59 {
60 	struct ptp_extts_request extts_request;
61 	unsigned long request[2] = {
62 		PTP_EXTTS_REQUEST,
63 		PTP_EXTTS_REQUEST2,
64 	};
65 	unsigned int enable_flags[5] = {
66 		PTP_ENABLE_FEATURE,
67 		PTP_ENABLE_FEATURE | PTP_RISING_EDGE,
68 		PTP_ENABLE_FEATURE | PTP_FALLING_EDGE,
69 		PTP_ENABLE_FEATURE | PTP_RISING_EDGE | PTP_FALLING_EDGE,
70 		PTP_ENABLE_FEATURE | (PTP_EXTTS_VALID_FLAGS + 1),
71 	};
72 	int err, i, j;
73 
74 	memset(&extts_request, 0, sizeof(extts_request));
75 	extts_request.index = index;
76 
77 	for (i = 0; i < 2; i++) {
78 		for (j = 0; j < 5; j++) {
79 			extts_request.flags = enable_flags[j];
80 			err = ioctl(fd, request[i], &extts_request);
81 			show_flag_test(i, extts_request.flags, err);
82 
83 			extts_request.flags = 0;
84 			err = ioctl(fd, request[i], &extts_request);
85 		}
86 	}
87 }
88 
get_clockid(int fd)89 static clockid_t get_clockid(int fd)
90 {
91 #define CLOCKFD 3
92 	return (((unsigned int) ~fd) << 3) | CLOCKFD;
93 }
94 
ppb_to_scaled_ppm(int ppb)95 static long ppb_to_scaled_ppm(int ppb)
96 {
97 	/*
98 	 * The 'freq' field in the 'struct timex' is in parts per
99 	 * million, but with a 16 bit binary fractional field.
100 	 * Instead of calculating either one of
101 	 *
102 	 *    scaled_ppm = (ppb / 1000) << 16  [1]
103 	 *    scaled_ppm = (ppb << 16) / 1000  [2]
104 	 *
105 	 * we simply use double precision math, in order to avoid the
106 	 * truncation in [1] and the possible overflow in [2].
107 	 */
108 	return (long) (ppb * 65.536);
109 }
110 
pctns(struct ptp_clock_time * t)111 static int64_t pctns(struct ptp_clock_time *t)
112 {
113 	return t->sec * NSEC_PER_SEC + t->nsec;
114 }
115 
usage(char * progname)116 static void usage(char *progname)
117 {
118 	fprintf(stderr,
119 		"usage: %s [options]\n"
120 		" -c         query the ptp clock's capabilities\n"
121 		" -d name    device to open\n"
122 		" -e val     read 'val' external time stamp events\n"
123 		" -E val     enable rising (1), falling (2), or both (3) edges\n"
124 		" -f val     adjust the ptp clock frequency by 'val' ppb\n"
125 		" -F chan    Enable single channel mask and keep device open for debugfs verification.\n"
126 		" -g         get the ptp clock time\n"
127 		" -h         prints this message\n"
128 		" -i val     index for event/trigger\n"
129 		" -k val     measure the time offset between system and phc clock\n"
130 		"            for 'val' times (Maximum 25)\n"
131 		" -l         list the current pin configuration\n"
132 		" -L pin,val configure pin index 'pin' with function 'val'\n"
133 		"            the channel index is taken from the '-i' option\n"
134 		"            'val' specifies the auxiliary function:\n"
135 		"            0 - none\n"
136 		"            1 - external time stamp\n"
137 		"            2 - periodic output\n"
138 		" -n val     shift the ptp clock time by 'val' nanoseconds\n"
139 		" -o val     phase offset (in nanoseconds) to be provided to the PHC servo\n"
140 		" -p val     enable output with a period of 'val' nanoseconds\n"
141 		" -H val     set output phase to 'val' nanoseconds (requires -p)\n"
142 		" -w val     set output pulse width to 'val' nanoseconds (requires -p)\n"
143 		" -P val     enable or disable (val=1|0) the system clock PPS\n"
144 		" -r         open the ptp clock in readonly mode\n"
145 		" -s         set the ptp clock time from the system time\n"
146 		" -S         set the system time from the ptp clock time\n"
147 		" -t val     shift the ptp clock time by 'val' seconds\n"
148 		" -T val     set the ptp clock time to 'val' seconds\n"
149 		" -x val     get an extended ptp clock time with the desired number of samples (up to %d)\n"
150 		" -X         get a ptp clock cross timestamp\n"
151 		" -y val     pre/post tstamp timebase to use {realtime|monotonic|monotonic-raw}\n"
152 		" -z         test combinations of rising/falling external time stamp flags\n",
153 		progname, PTP_MAX_SAMPLES);
154 }
155 
main(int argc,char * argv[])156 int main(int argc, char *argv[])
157 {
158 	struct ptp_clock_caps caps;
159 	struct ptp_extts_event event;
160 	struct ptp_extts_request extts_request;
161 	struct ptp_perout_request perout_request;
162 	struct ptp_pin_desc desc;
163 	struct timespec ts;
164 	struct timex tx;
165 	struct ptp_clock_time *pct;
166 	struct ptp_sys_offset *sysoff;
167 	struct ptp_sys_offset_extended *soe;
168 	struct ptp_sys_offset_precise *xts;
169 
170 	char *progname;
171 	unsigned int i;
172 	int c, cnt, fd;
173 
174 	char *device = DEVICE;
175 	clockid_t clkid;
176 	int adjfreq = 0x7fffffff;
177 	int adjtime = 0;
178 	int adjns = 0;
179 	int adjphase = 0;
180 	int capabilities = 0;
181 	int extts = 0;
182 	int edge = 0;
183 	int flagtest = 0;
184 	int gettime = 0;
185 	int index = 0;
186 	int list_pins = 0;
187 	int pct_offset = 0;
188 	int getextended = 0;
189 	int getcross = 0;
190 	int n_samples = 0;
191 	int pin_index = -1, pin_func;
192 	int pps = -1;
193 	int seconds = 0;
194 	int readonly = 0;
195 	int settime = 0;
196 	int channel = -1;
197 	clockid_t ext_clockid = CLOCK_REALTIME;
198 
199 	int64_t t1, t2, tp;
200 	int64_t interval, offset;
201 	int64_t perout_phase = -1;
202 	int64_t pulsewidth = -1;
203 	int64_t perout = -1;
204 
205 	progname = strrchr(argv[0], '/');
206 	progname = progname ? 1+progname : argv[0];
207 	while (EOF != (c = getopt(argc, argv, "cd:e:E:f:F:ghH:i:k:lL:n:o:p:P:rsSt:T:w:x:Xy:z"))) {
208 		switch (c) {
209 		case 'c':
210 			capabilities = 1;
211 			break;
212 		case 'd':
213 			device = optarg;
214 			break;
215 		case 'e':
216 			extts = atoi(optarg);
217 			break;
218 		case 'E':
219 			edge = atoi(optarg);
220 			edge = (edge & 1 ? PTP_RISING_EDGE : 0) |
221 				(edge & 2 ? PTP_FALLING_EDGE : 0);
222 			break;
223 		case 'f':
224 			adjfreq = atoi(optarg);
225 			break;
226 		case 'F':
227 			channel = atoi(optarg);
228 			break;
229 		case 'g':
230 			gettime = 1;
231 			break;
232 		case 'H':
233 			perout_phase = atoll(optarg);
234 			break;
235 		case 'i':
236 			index = atoi(optarg);
237 			break;
238 		case 'k':
239 			pct_offset = 1;
240 			n_samples = atoi(optarg);
241 			break;
242 		case 'l':
243 			list_pins = 1;
244 			break;
245 		case 'L':
246 			cnt = sscanf(optarg, "%d,%d", &pin_index, &pin_func);
247 			if (cnt != 2) {
248 				usage(progname);
249 				return -1;
250 			}
251 			break;
252 		case 'n':
253 			adjns = atoi(optarg);
254 			break;
255 		case 'o':
256 			adjphase = atoi(optarg);
257 			break;
258 		case 'p':
259 			perout = atoll(optarg);
260 			break;
261 		case 'P':
262 			pps = atoi(optarg);
263 			break;
264 		case 'r':
265 			readonly = 1;
266 			break;
267 		case 's':
268 			settime = 1;
269 			break;
270 		case 'S':
271 			settime = 2;
272 			break;
273 		case 't':
274 			adjtime = atoi(optarg);
275 			break;
276 		case 'T':
277 			settime = 3;
278 			seconds = atoi(optarg);
279 			break;
280 		case 'w':
281 			pulsewidth = atoi(optarg);
282 			break;
283 		case 'x':
284 			getextended = atoi(optarg);
285 			if (getextended < 1 || getextended > PTP_MAX_SAMPLES) {
286 				fprintf(stderr,
287 					"number of extended timestamp samples must be between 1 and %d; was asked for %d\n",
288 					PTP_MAX_SAMPLES, getextended);
289 				return -1;
290 			}
291 			break;
292 		case 'X':
293 			getcross = 1;
294 			break;
295 		case 'y':
296 			if (!strcasecmp(optarg, "realtime"))
297 				ext_clockid = CLOCK_REALTIME;
298 			else if (!strcasecmp(optarg, "monotonic"))
299 				ext_clockid = CLOCK_MONOTONIC;
300 			else if (!strcasecmp(optarg, "monotonic-raw"))
301 				ext_clockid = CLOCK_MONOTONIC_RAW;
302 			else {
303 				fprintf(stderr,
304 					"type needs to be realtime, monotonic or monotonic-raw; was given %s\n",
305 					optarg);
306 				return -1;
307 			}
308 			break;
309 
310 		case 'z':
311 			flagtest = 1;
312 			break;
313 		case 'h':
314 			usage(progname);
315 			return 0;
316 		case '?':
317 		default:
318 			usage(progname);
319 			return -1;
320 		}
321 	}
322 
323 	fd = open(device, readonly ? O_RDONLY : O_RDWR);
324 	if (fd < 0) {
325 		fprintf(stderr, "opening %s: %s\n", device, strerror(errno));
326 		return -1;
327 	}
328 
329 	clkid = get_clockid(fd);
330 	if (CLOCK_INVALID == clkid) {
331 		fprintf(stderr, "failed to read clock id\n");
332 		return -1;
333 	}
334 
335 	if (capabilities) {
336 		if (ioctl(fd, PTP_CLOCK_GETCAPS, &caps)) {
337 			perror("PTP_CLOCK_GETCAPS");
338 		} else {
339 			printf("capabilities:\n"
340 			       "  %d maximum frequency adjustment (ppb)\n"
341 			       "  %d programmable alarms\n"
342 			       "  %d external time stamp channels\n"
343 			       "  %d programmable periodic signals\n"
344 			       "  %d pulse per second\n"
345 			       "  %d programmable pins\n"
346 			       "  %d cross timestamping\n"
347 			       "  %d adjust_phase\n"
348 			       "  %d maximum phase adjustment (ns)\n",
349 			       caps.max_adj,
350 			       caps.n_alarm,
351 			       caps.n_ext_ts,
352 			       caps.n_per_out,
353 			       caps.pps,
354 			       caps.n_pins,
355 			       caps.cross_timestamping,
356 			       caps.adjust_phase,
357 			       caps.max_phase_adj);
358 		}
359 	}
360 
361 	if (0x7fffffff != adjfreq) {
362 		memset(&tx, 0, sizeof(tx));
363 		tx.modes = ADJ_FREQUENCY;
364 		tx.freq = ppb_to_scaled_ppm(adjfreq);
365 		if (clock_adjtime(clkid, &tx)) {
366 			perror("clock_adjtime");
367 		} else {
368 			puts("frequency adjustment okay");
369 		}
370 	}
371 
372 	if (adjtime || adjns) {
373 		memset(&tx, 0, sizeof(tx));
374 		tx.modes = ADJ_SETOFFSET | ADJ_NANO;
375 		tx.time.tv_sec = adjtime;
376 		tx.time.tv_usec = adjns;
377 		while (tx.time.tv_usec < 0) {
378 			tx.time.tv_sec  -= 1;
379 			tx.time.tv_usec += NSEC_PER_SEC;
380 		}
381 
382 		if (clock_adjtime(clkid, &tx) < 0) {
383 			perror("clock_adjtime");
384 		} else {
385 			puts("time shift okay");
386 		}
387 	}
388 
389 	if (adjphase) {
390 		memset(&tx, 0, sizeof(tx));
391 		tx.modes = ADJ_OFFSET | ADJ_NANO;
392 		tx.offset = adjphase;
393 
394 		if (clock_adjtime(clkid, &tx) < 0) {
395 			perror("clock_adjtime");
396 		} else {
397 			puts("phase adjustment okay");
398 		}
399 	}
400 
401 	if (gettime) {
402 		if (clock_gettime(clkid, &ts)) {
403 			perror("clock_gettime");
404 		} else {
405 			printf("clock time: %ld.%09ld or %s",
406 			       ts.tv_sec, ts.tv_nsec, ctime(&ts.tv_sec));
407 		}
408 	}
409 
410 	if (settime == 1) {
411 		clock_gettime(CLOCK_REALTIME, &ts);
412 		if (clock_settime(clkid, &ts)) {
413 			perror("clock_settime");
414 		} else {
415 			puts("set time okay");
416 		}
417 	}
418 
419 	if (settime == 2) {
420 		clock_gettime(clkid, &ts);
421 		if (clock_settime(CLOCK_REALTIME, &ts)) {
422 			perror("clock_settime");
423 		} else {
424 			puts("set time okay");
425 		}
426 	}
427 
428 	if (settime == 3) {
429 		ts.tv_sec = seconds;
430 		ts.tv_nsec = 0;
431 		if (clock_settime(clkid, &ts)) {
432 			perror("clock_settime");
433 		} else {
434 			puts("set time okay");
435 		}
436 	}
437 
438 	if (pin_index >= 0) {
439 		memset(&desc, 0, sizeof(desc));
440 		desc.index = pin_index;
441 		desc.func = pin_func;
442 		desc.chan = index;
443 		if (ioctl(fd, PTP_PIN_SETFUNC, &desc)) {
444 			perror("PTP_PIN_SETFUNC");
445 		} else {
446 			puts("set pin function okay");
447 		}
448 	}
449 
450 	if (extts) {
451 		if (!readonly) {
452 			memset(&extts_request, 0, sizeof(extts_request));
453 			extts_request.index = index;
454 			extts_request.flags = PTP_ENABLE_FEATURE | edge;
455 			if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_request)) {
456 				perror("PTP_EXTTS_REQUEST");
457 				extts = 0;
458 			} else {
459 				puts("external time stamp request okay");
460 			}
461 		}
462 		for (; extts; extts--) {
463 			cnt = read(fd, &event, sizeof(event));
464 			if (cnt != sizeof(event)) {
465 				perror("read");
466 				break;
467 			}
468 			printf("event index %u at %lld.%09u\n", event.index,
469 			       event.t.sec, event.t.nsec);
470 			fflush(stdout);
471 		}
472 		if (!readonly) {
473 			/* Disable the feature again. */
474 			extts_request.flags = 0;
475 			if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_request)) {
476 				perror("PTP_EXTTS_REQUEST");
477 			}
478 		}
479 	}
480 
481 	if (flagtest) {
482 		do_flag_test(fd, index);
483 	}
484 
485 	if (list_pins) {
486 		int n_pins = 0;
487 		if (ioctl(fd, PTP_CLOCK_GETCAPS, &caps)) {
488 			perror("PTP_CLOCK_GETCAPS");
489 		} else {
490 			n_pins = caps.n_pins;
491 		}
492 		for (i = 0; i < n_pins; i++) {
493 			desc.index = i;
494 			if (ioctl(fd, PTP_PIN_GETFUNC, &desc)) {
495 				perror("PTP_PIN_GETFUNC");
496 				break;
497 			}
498 			printf("name %s index %u func %u chan %u\n",
499 			       desc.name, desc.index, desc.func, desc.chan);
500 		}
501 	}
502 
503 	if (pulsewidth >= 0 && perout < 0) {
504 		puts("-w can only be specified together with -p");
505 		return -1;
506 	}
507 
508 	if (perout_phase >= 0 && perout < 0) {
509 		puts("-H can only be specified together with -p");
510 		return -1;
511 	}
512 
513 	if (perout >= 0) {
514 		if (clock_gettime(clkid, &ts)) {
515 			perror("clock_gettime");
516 			return -1;
517 		}
518 		memset(&perout_request, 0, sizeof(perout_request));
519 		perout_request.index = index;
520 		perout_request.period.sec = perout / NSEC_PER_SEC;
521 		perout_request.period.nsec = perout % NSEC_PER_SEC;
522 		perout_request.flags = 0;
523 		if (pulsewidth >= 0) {
524 			perout_request.flags |= PTP_PEROUT_DUTY_CYCLE;
525 			perout_request.on.sec = pulsewidth / NSEC_PER_SEC;
526 			perout_request.on.nsec = pulsewidth % NSEC_PER_SEC;
527 		}
528 		if (perout_phase >= 0) {
529 			perout_request.flags |= PTP_PEROUT_PHASE;
530 			perout_request.phase.sec = perout_phase / NSEC_PER_SEC;
531 			perout_request.phase.nsec = perout_phase % NSEC_PER_SEC;
532 		} else {
533 			perout_request.start.sec = ts.tv_sec + 2;
534 			perout_request.start.nsec = 0;
535 		}
536 
537 		if (ioctl(fd, PTP_PEROUT_REQUEST2, &perout_request)) {
538 			perror("PTP_PEROUT_REQUEST");
539 		} else {
540 			puts("periodic output request okay");
541 		}
542 	}
543 
544 	if (pps != -1) {
545 		int enable = pps ? 1 : 0;
546 		if (ioctl(fd, PTP_ENABLE_PPS, enable)) {
547 			perror("PTP_ENABLE_PPS");
548 		} else {
549 			puts("pps for system time request okay");
550 		}
551 	}
552 
553 	if (pct_offset) {
554 		if (n_samples <= 0 || n_samples > 25) {
555 			puts("n_samples should be between 1 and 25");
556 			usage(progname);
557 			return -1;
558 		}
559 
560 		sysoff = calloc(1, sizeof(*sysoff));
561 		if (!sysoff) {
562 			perror("calloc");
563 			return -1;
564 		}
565 		sysoff->n_samples = n_samples;
566 
567 		if (ioctl(fd, PTP_SYS_OFFSET, sysoff))
568 			perror("PTP_SYS_OFFSET");
569 		else
570 			puts("system and phc clock time offset request okay");
571 
572 		pct = &sysoff->ts[0];
573 		for (i = 0; i < sysoff->n_samples; i++) {
574 			t1 = pctns(pct+2*i);
575 			tp = pctns(pct+2*i+1);
576 			t2 = pctns(pct+2*i+2);
577 			interval = t2 - t1;
578 			offset = (t2 + t1) / 2 - tp;
579 
580 			printf("system time: %lld.%09u\n",
581 				(pct+2*i)->sec, (pct+2*i)->nsec);
582 			printf("phc    time: %lld.%09u\n",
583 				(pct+2*i+1)->sec, (pct+2*i+1)->nsec);
584 			printf("system time: %lld.%09u\n",
585 				(pct+2*i+2)->sec, (pct+2*i+2)->nsec);
586 			printf("system/phc clock time offset is %" PRId64 " ns\n"
587 			       "system     clock time delay  is %" PRId64 " ns\n",
588 				offset, interval);
589 		}
590 
591 		free(sysoff);
592 	}
593 
594 	if (getextended) {
595 		soe = calloc(1, sizeof(*soe));
596 		if (!soe) {
597 			perror("calloc");
598 			return -1;
599 		}
600 
601 		soe->n_samples = getextended;
602 		soe->clockid = ext_clockid;
603 
604 		if (ioctl(fd, PTP_SYS_OFFSET_EXTENDED, soe)) {
605 			perror("PTP_SYS_OFFSET_EXTENDED");
606 		} else {
607 			printf("extended timestamp request returned %d samples\n",
608 			       getextended);
609 
610 			for (i = 0; i < getextended; i++) {
611 				switch (ext_clockid) {
612 				case CLOCK_REALTIME:
613 					printf("sample #%2d: real time before: %lld.%09u\n",
614 					       i, soe->ts[i][0].sec,
615 					       soe->ts[i][0].nsec);
616 					break;
617 				case CLOCK_MONOTONIC:
618 					printf("sample #%2d: monotonic time before: %lld.%09u\n",
619 					       i, soe->ts[i][0].sec,
620 					       soe->ts[i][0].nsec);
621 					break;
622 				case CLOCK_MONOTONIC_RAW:
623 					printf("sample #%2d: monotonic-raw time before: %lld.%09u\n",
624 					       i, soe->ts[i][0].sec,
625 					       soe->ts[i][0].nsec);
626 					break;
627 				default:
628 					break;
629 				}
630 				printf("            phc time: %lld.%09u\n",
631 				       soe->ts[i][1].sec, soe->ts[i][1].nsec);
632 				switch (ext_clockid) {
633 				case CLOCK_REALTIME:
634 					printf("            real time after: %lld.%09u\n",
635 					       soe->ts[i][2].sec,
636 					       soe->ts[i][2].nsec);
637 					break;
638 				case CLOCK_MONOTONIC:
639 					printf("            monotonic time after: %lld.%09u\n",
640 					       soe->ts[i][2].sec,
641 					       soe->ts[i][2].nsec);
642 					break;
643 				case CLOCK_MONOTONIC_RAW:
644 					printf("            monotonic-raw time after: %lld.%09u\n",
645 					       soe->ts[i][2].sec,
646 					       soe->ts[i][2].nsec);
647 					break;
648 				default:
649 					break;
650 				}
651 			}
652 		}
653 
654 		free(soe);
655 	}
656 
657 	if (getcross) {
658 		xts = calloc(1, sizeof(*xts));
659 		if (!xts) {
660 			perror("calloc");
661 			return -1;
662 		}
663 
664 		if (ioctl(fd, PTP_SYS_OFFSET_PRECISE, xts)) {
665 			perror("PTP_SYS_OFFSET_PRECISE");
666 		} else {
667 			puts("system and phc crosstimestamping request okay");
668 
669 			printf("device time: %lld.%09u\n",
670 			       xts->device.sec, xts->device.nsec);
671 			printf("system time: %lld.%09u\n",
672 			       xts->sys_realtime.sec, xts->sys_realtime.nsec);
673 			printf("monoraw time: %lld.%09u\n",
674 			       xts->sys_monoraw.sec, xts->sys_monoraw.nsec);
675 		}
676 
677 		free(xts);
678 	}
679 
680 	if (channel >= 0) {
681 		if (ioctl(fd, PTP_MASK_CLEAR_ALL)) {
682 			perror("PTP_MASK_CLEAR_ALL");
683 		} else if (ioctl(fd, PTP_MASK_EN_SINGLE, (unsigned int *)&channel)) {
684 			perror("PTP_MASK_EN_SINGLE");
685 		} else {
686 			printf("Channel %d exclusively enabled. Check on debugfs.\n", channel);
687 			printf("Press any key to continue\n.");
688 			getchar();
689 		}
690 	}
691 
692 	close(fd);
693 	return 0;
694 }
695