1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Industrialio buffer test code.
3  *
4  * Copyright (c) 2008 Jonathan Cameron
5  *
6  * This program is primarily intended as an example application.
7  * Reads the current buffer setup from sysfs and starts a short capture
8  * from the specified device, pretty printing the result after appropriate
9  * conversion.
10  *
11  * Command line parameters
12  * generic_buffer -n <device_name> -t <trigger_name>
13  * If trigger name is not specified the program assumes you want a dataready
14  * trigger associated with the device and goes looking for it.
15  */
16 
17 #include <unistd.h>
18 #include <stdlib.h>
19 #include <dirent.h>
20 #include <fcntl.h>
21 #include <stdio.h>
22 #include <errno.h>
23 #include <sys/stat.h>
24 #include <sys/dir.h>
25 #include <linux/types.h>
26 #include <string.h>
27 #include <poll.h>
28 #include <endian.h>
29 #include <getopt.h>
30 #include <inttypes.h>
31 #include <stdbool.h>
32 #include <signal.h>
33 #include <sys/ioctl.h>
34 #include <linux/iio/buffer.h>
35 #include "iio_utils.h"
36 
37 /**
38  * enum autochan - state for the automatic channel enabling mechanism
39  */
40 enum autochan {
41 	AUTOCHANNELS_DISABLED,
42 	AUTOCHANNELS_ENABLED,
43 	AUTOCHANNELS_ACTIVE,
44 };
45 
46 /**
47  * size_from_channelarray() - calculate the storage size of a scan
48  * @channels:		the channel info array
49  * @num_channels:	number of channels
50  *
51  * Has the side effect of filling the channels[i].location values used
52  * in processing the buffer output.
53  **/
54 static unsigned int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
55 {
56 	unsigned int bytes = 0;
57 	int i = 0;
58 
59 	while (i < num_channels) {
60 		if (bytes % channels[i].bytes == 0)
61 			channels[i].location = bytes;
62 		else
63 			channels[i].location = bytes - bytes % channels[i].bytes
64 					       + channels[i].bytes;
65 
66 		bytes = channels[i].location + channels[i].bytes;
67 		i++;
68 	}
69 
70 	return bytes;
71 }
72 
73 static void print1byte(uint8_t input, struct iio_channel_info *info)
74 {
75 	/*
76 	 * Shift before conversion to avoid sign extension
77 	 * of left aligned data
78 	 */
79 	input >>= info->shift;
80 	input &= info->mask;
81 	if (info->is_signed) {
82 		int8_t val = (int8_t)(input << (8 - info->bits_used)) >>
83 			     (8 - info->bits_used);
84 		printf("%05f ", ((float)val + info->offset) * info->scale);
85 	} else {
86 		printf("%05f ", ((float)input + info->offset) * info->scale);
87 	}
88 }
89 
90 static void print2byte(uint16_t input, struct iio_channel_info *info)
91 {
92 	/* First swap if incorrect endian */
93 	if (info->be)
94 		input = be16toh(input);
95 	else
96 		input = le16toh(input);
97 
98 	/*
99 	 * Shift before conversion to avoid sign extension
100 	 * of left aligned data
101 	 */
102 	input >>= info->shift;
103 	input &= info->mask;
104 	if (info->is_signed) {
105 		int16_t val = (int16_t)(input << (16 - info->bits_used)) >>
106 			      (16 - info->bits_used);
107 		printf("%05f ", ((float)val + info->offset) * info->scale);
108 	} else {
109 		printf("%05f ", ((float)input + info->offset) * info->scale);
110 	}
111 }
112 
113 static void print4byte(uint32_t input, struct iio_channel_info *info)
114 {
115 	/* First swap if incorrect endian */
116 	if (info->be)
117 		input = be32toh(input);
118 	else
119 		input = le32toh(input);
120 
121 	/*
122 	 * Shift before conversion to avoid sign extension
123 	 * of left aligned data
124 	 */
125 	input >>= info->shift;
126 	input &= info->mask;
127 	if (info->is_signed) {
128 		int32_t val = (int32_t)(input << (32 - info->bits_used)) >>
129 			      (32 - info->bits_used);
130 		printf("%05f ", ((float)val + info->offset) * info->scale);
131 	} else {
132 		printf("%05f ", ((float)input + info->offset) * info->scale);
133 	}
134 }
135 
136 static void print8byte(uint64_t input, struct iio_channel_info *info)
137 {
138 	/* First swap if incorrect endian */
139 	if (info->be)
140 		input = be64toh(input);
141 	else
142 		input = le64toh(input);
143 
144 	/*
145 	 * Shift before conversion to avoid sign extension
146 	 * of left aligned data
147 	 */
148 	input >>= info->shift;
149 	input &= info->mask;
150 	if (info->is_signed) {
151 		int64_t val = (int64_t)(input << (64 - info->bits_used)) >>
152 			      (64 - info->bits_used);
153 		/* special case for timestamp */
154 		if (info->scale == 1.0f && info->offset == 0.0f)
155 			printf("%" PRId64 " ", val);
156 		else
157 			printf("%05f ",
158 			       ((float)val + info->offset) * info->scale);
159 	} else {
160 		printf("%05f ", ((float)input + info->offset) * info->scale);
161 	}
162 }
163 
164 /**
165  * process_scan() - print out the values in SI units
166  * @data:		pointer to the start of the scan
167  * @channels:		information about the channels.
168  *			Note: size_from_channelarray must have been called first
169  *			      to fill the location offsets.
170  * @num_channels:	number of channels
171  **/
172 static void process_scan(char *data, struct iio_channel_info *channels,
173 			 int num_channels)
174 {
175 	int k;
176 
177 	for (k = 0; k < num_channels; k++)
178 		switch (channels[k].bytes) {
179 			/* only a few cases implemented so far */
180 		case 1:
181 			print1byte(*(uint8_t *)(data + channels[k].location),
182 				   &channels[k]);
183 			break;
184 		case 2:
185 			print2byte(*(uint16_t *)(data + channels[k].location),
186 				   &channels[k]);
187 			break;
188 		case 4:
189 			print4byte(*(uint32_t *)(data + channels[k].location),
190 				   &channels[k]);
191 			break;
192 		case 8:
193 			print8byte(*(uint64_t *)(data + channels[k].location),
194 				   &channels[k]);
195 			break;
196 		default:
197 			break;
198 		}
199 	printf("\n");
200 }
201 
202 static int enable_disable_all_channels(char *dev_dir_name, int buffer_idx, int enable)
203 {
204 	const struct dirent *ent;
205 	char scanelemdir[256];
206 	DIR *dp;
207 	int ret;
208 
209 	snprintf(scanelemdir, sizeof(scanelemdir),
210 		 FORMAT_SCAN_ELEMENTS_DIR, dev_dir_name, buffer_idx);
211 	scanelemdir[sizeof(scanelemdir)-1] = '\0';
212 
213 	dp = opendir(scanelemdir);
214 	if (!dp) {
215 		fprintf(stderr, "Enabling/disabling channels: can't open %s\n",
216 			scanelemdir);
217 		return -EIO;
218 	}
219 
220 	ret = -ENOENT;
221 	while (ent = readdir(dp), ent) {
222 		if (iioutils_check_suffix(ent->d_name, "_en")) {
223 			printf("%sabling: %s\n",
224 			       enable ? "En" : "Dis",
225 			       ent->d_name);
226 			ret = write_sysfs_int(ent->d_name, scanelemdir,
227 					      enable);
228 			if (ret < 0)
229 				fprintf(stderr, "Failed to enable/disable %s\n",
230 					ent->d_name);
231 		}
232 	}
233 
234 	if (closedir(dp) == -1) {
235 		perror("Enabling/disabling channels: "
236 		       "Failed to close directory");
237 		return -errno;
238 	}
239 	return 0;
240 }
241 
242 static void print_usage(void)
243 {
244 	fprintf(stderr, "Usage: generic_buffer [options]...\n"
245 		"Capture, convert and output data from IIO device buffer\n"
246 		"  -a         Auto-activate all available channels\n"
247 		"  -A         Force-activate ALL channels\n"
248 		"  -b <n>     The buffer which to open (by index), default 0\n"
249 		"  -c <n>     Do n conversions, or loop forever if n < 0\n"
250 		"  -e         Disable wait for event (new data)\n"
251 		"  -g         Use trigger-less mode\n"
252 		"  -l <n>     Set buffer length to n samples\n"
253 		"  --device-name -n <name>\n"
254 		"  --device-num -N <num>\n"
255 		"        Set device by name or number (mandatory)\n"
256 		"  --trigger-name -t <name>\n"
257 		"  --trigger-num -T <num>\n"
258 		"        Set trigger by name or number\n"
259 		"  -w <n>     Set delay between reads in us (event-less mode)\n");
260 }
261 
262 static enum autochan autochannels = AUTOCHANNELS_DISABLED;
263 static char *dev_dir_name = NULL;
264 static char *buf_dir_name = NULL;
265 static int buffer_idx = 0;
266 static bool current_trigger_set = false;
267 
268 static void cleanup(void)
269 {
270 	int ret;
271 
272 	/* Disable trigger */
273 	if (dev_dir_name && current_trigger_set) {
274 		/* Disconnect the trigger - just write a dummy name. */
275 		ret = write_sysfs_string("trigger/current_trigger",
276 					 dev_dir_name, "NULL");
277 		if (ret < 0)
278 			fprintf(stderr, "Failed to disable trigger: %s\n",
279 				strerror(-ret));
280 		current_trigger_set = false;
281 	}
282 
283 	/* Disable buffer */
284 	if (buf_dir_name) {
285 		ret = write_sysfs_int("enable", buf_dir_name, 0);
286 		if (ret < 0)
287 			fprintf(stderr, "Failed to disable buffer: %s\n",
288 				strerror(-ret));
289 	}
290 
291 	/* Disable channels if auto-enabled */
292 	if (dev_dir_name && autochannels == AUTOCHANNELS_ACTIVE) {
293 		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 0);
294 		if (ret)
295 			fprintf(stderr, "Failed to disable all channels\n");
296 		autochannels = AUTOCHANNELS_DISABLED;
297 	}
298 }
299 
300 static void sig_handler(int signum)
301 {
302 	fprintf(stderr, "Caught signal %d\n", signum);
303 	cleanup();
304 	exit(-signum);
305 }
306 
307 static void register_cleanup(void)
308 {
309 	struct sigaction sa = { .sa_handler = sig_handler };
310 	const int signums[] = { SIGINT, SIGTERM, SIGABRT };
311 	int ret, i;
312 
313 	for (i = 0; i < ARRAY_SIZE(signums); ++i) {
314 		ret = sigaction(signums[i], &sa, NULL);
315 		if (ret) {
316 			perror("Failed to register signal handler");
317 			exit(-1);
318 		}
319 	}
320 }
321 
322 static const struct option longopts[] = {
323 	{ "device-name",	1, 0, 'n' },
324 	{ "device-num",		1, 0, 'N' },
325 	{ "trigger-name",	1, 0, 't' },
326 	{ "trigger-num",	1, 0, 'T' },
327 	{ },
328 };
329 
330 int main(int argc, char **argv)
331 {
332 	long long num_loops = 2;
333 	unsigned long timedelay = 1000000;
334 	unsigned long buf_len = 128;
335 
336 	ssize_t i;
337 	unsigned long long j;
338 	unsigned long toread;
339 	int ret, c;
340 	struct stat st;
341 	int fd = -1;
342 	int buf_fd = -1;
343 
344 	int num_channels = 0;
345 	char *trigger_name = NULL, *device_name = NULL;
346 
347 	char *data = NULL;
348 	ssize_t read_size;
349 	int dev_num = -1, trig_num = -1;
350 	char *buffer_access = NULL;
351 	unsigned int scan_size;
352 	int noevents = 0;
353 	int notrigger = 0;
354 	char *dummy;
355 	bool force_autochannels = false;
356 
357 	struct iio_channel_info *channels = NULL;
358 
359 	register_cleanup();
360 
361 	while ((c = getopt_long(argc, argv, "aAb:c:egl:n:N:t:T:w:?", longopts,
362 				NULL)) != -1) {
363 		switch (c) {
364 		case 'a':
365 			autochannels = AUTOCHANNELS_ENABLED;
366 			break;
367 		case 'A':
368 			autochannels = AUTOCHANNELS_ENABLED;
369 			force_autochannels = true;
370 			break;
371 		case 'b':
372 			errno = 0;
373 			buffer_idx = strtoll(optarg, &dummy, 10);
374 			if (errno) {
375 				ret = -errno;
376 				goto error;
377 			}
378 			if (buffer_idx < 0) {
379 				ret = -ERANGE;
380 				goto error;
381 			}
382 
383 			break;
384 		case 'c':
385 			errno = 0;
386 			num_loops = strtoll(optarg, &dummy, 10);
387 			if (errno) {
388 				ret = -errno;
389 				goto error;
390 			}
391 
392 			break;
393 		case 'e':
394 			noevents = 1;
395 			break;
396 		case 'g':
397 			notrigger = 1;
398 			break;
399 		case 'l':
400 			errno = 0;
401 			buf_len = strtoul(optarg, &dummy, 10);
402 			if (errno) {
403 				ret = -errno;
404 				goto error;
405 			}
406 
407 			break;
408 		case 'n':
409 			device_name = strdup(optarg);
410 			break;
411 		case 'N':
412 			errno = 0;
413 			dev_num = strtoul(optarg, &dummy, 10);
414 			if (errno) {
415 				ret = -errno;
416 				goto error;
417 			}
418 			break;
419 		case 't':
420 			trigger_name = strdup(optarg);
421 			break;
422 		case 'T':
423 			errno = 0;
424 			trig_num = strtoul(optarg, &dummy, 10);
425 			if (errno)
426 				return -errno;
427 			break;
428 		case 'w':
429 			errno = 0;
430 			timedelay = strtoul(optarg, &dummy, 10);
431 			if (errno) {
432 				ret = -errno;
433 				goto error;
434 			}
435 			break;
436 		case '?':
437 			print_usage();
438 			ret = -1;
439 			goto error;
440 		}
441 	}
442 
443 	/* Find the device requested */
444 	if (dev_num < 0 && !device_name) {
445 		fprintf(stderr, "Device not set\n");
446 		print_usage();
447 		ret = -1;
448 		goto error;
449 	} else if (dev_num >= 0 && device_name) {
450 		fprintf(stderr, "Only one of --device-num or --device-name needs to be set\n");
451 		print_usage();
452 		ret = -1;
453 		goto error;
454 	} else if (dev_num < 0) {
455 		dev_num = find_type_by_name(device_name, "iio:device");
456 		if (dev_num < 0) {
457 			fprintf(stderr, "Failed to find the %s\n", device_name);
458 			ret = dev_num;
459 			goto error;
460 		}
461 	}
462 	printf("iio device number being used is %d\n", dev_num);
463 
464 	ret = asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
465 	if (ret < 0)
466 		return -ENOMEM;
467 	/* Fetch device_name if specified by number */
468 	if (!device_name) {
469 		device_name = malloc(IIO_MAX_NAME_LENGTH);
470 		if (!device_name) {
471 			ret = -ENOMEM;
472 			goto error;
473 		}
474 		ret = read_sysfs_string("name", dev_dir_name, device_name);
475 		if (ret < 0) {
476 			fprintf(stderr, "Failed to read name of device %d\n", dev_num);
477 			goto error;
478 		}
479 	}
480 
481 	if (notrigger) {
482 		printf("trigger-less mode selected\n");
483 	} else if (trig_num >= 0) {
484 		char *trig_dev_name;
485 		ret = asprintf(&trig_dev_name, "%strigger%d", iio_dir, trig_num);
486 		if (ret < 0) {
487 			return -ENOMEM;
488 		}
489 		trigger_name = malloc(IIO_MAX_NAME_LENGTH);
490 		ret = read_sysfs_string("name", trig_dev_name, trigger_name);
491 		free(trig_dev_name);
492 		if (ret < 0) {
493 			fprintf(stderr, "Failed to read trigger%d name from\n", trig_num);
494 			return ret;
495 		}
496 		printf("iio trigger number being used is %d\n", trig_num);
497 	} else {
498 		if (!trigger_name) {
499 			/*
500 			 * Build the trigger name. If it is device associated
501 			 * its name is <device_name>_dev[n] where n matches
502 			 * the device number found above.
503 			 */
504 			ret = asprintf(&trigger_name,
505 				       "%s-dev%d", device_name, dev_num);
506 			if (ret < 0) {
507 				ret = -ENOMEM;
508 				goto error;
509 			}
510 		}
511 
512 		/* Look for this "-devN" trigger */
513 		trig_num = find_type_by_name(trigger_name, "trigger");
514 		if (trig_num < 0) {
515 			/* OK try the simpler "-trigger" suffix instead */
516 			free(trigger_name);
517 			ret = asprintf(&trigger_name,
518 				       "%s-trigger", device_name);
519 			if (ret < 0) {
520 				ret = -ENOMEM;
521 				goto error;
522 			}
523 		}
524 
525 		trig_num = find_type_by_name(trigger_name, "trigger");
526 		if (trig_num < 0) {
527 			fprintf(stderr, "Failed to find the trigger %s\n",
528 				trigger_name);
529 			ret = trig_num;
530 			goto error;
531 		}
532 
533 		printf("iio trigger number being used is %d\n", trig_num);
534 	}
535 
536 	/*
537 	 * Parse the files in scan_elements to identify what channels are
538 	 * present
539 	 */
540 	ret = build_channel_array(dev_dir_name, buffer_idx, &channels, &num_channels);
541 	if (ret) {
542 		fprintf(stderr, "Problem reading scan element information\n"
543 			"diag %s\n", dev_dir_name);
544 		goto error;
545 	}
546 	if (num_channels && autochannels == AUTOCHANNELS_ENABLED &&
547 	    !force_autochannels) {
548 		fprintf(stderr, "Auto-channels selected but some channels "
549 			"are already activated in sysfs\n");
550 		fprintf(stderr, "Proceeding without activating any channels\n");
551 	}
552 
553 	if ((!num_channels && autochannels == AUTOCHANNELS_ENABLED) ||
554 	    (autochannels == AUTOCHANNELS_ENABLED && force_autochannels)) {
555 		fprintf(stderr, "Enabling all channels\n");
556 
557 		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 1);
558 		if (ret) {
559 			fprintf(stderr, "Failed to enable all channels\n");
560 			goto error;
561 		}
562 
563 		/* This flags that we need to disable the channels again */
564 		autochannels = AUTOCHANNELS_ACTIVE;
565 
566 		ret = build_channel_array(dev_dir_name, buffer_idx, &channels,
567 					  &num_channels);
568 		if (ret) {
569 			fprintf(stderr, "Problem reading scan element "
570 				"information\n"
571 				"diag %s\n", dev_dir_name);
572 			goto error;
573 		}
574 		if (!num_channels) {
575 			fprintf(stderr, "Still no channels after "
576 				"auto-enabling, giving up\n");
577 			goto error;
578 		}
579 	}
580 
581 	if (!num_channels && autochannels == AUTOCHANNELS_DISABLED) {
582 		fprintf(stderr,
583 			"No channels are enabled, we have nothing to scan.\n");
584 		fprintf(stderr, "Enable channels manually in "
585 			FORMAT_SCAN_ELEMENTS_DIR
586 			"/*_en or pass -a to autoenable channels and "
587 			"try again.\n", dev_dir_name, buffer_idx);
588 		ret = -ENOENT;
589 		goto error;
590 	}
591 
592 	/*
593 	 * Construct the directory name for the associated buffer.
594 	 * As we know that the lis3l02dq has only one buffer this may
595 	 * be built rather than found.
596 	 */
597 	ret = asprintf(&buf_dir_name,
598 		       "%siio:device%d/buffer%d", iio_dir, dev_num, buffer_idx);
599 	if (ret < 0) {
600 		ret = -ENOMEM;
601 		goto error;
602 	}
603 
604 	if (stat(buf_dir_name, &st)) {
605 		fprintf(stderr, "Could not stat() '%s', got error %d: %s\n",
606 			buf_dir_name, errno, strerror(errno));
607 		ret = -errno;
608 		goto error;
609 	}
610 
611 	if (!S_ISDIR(st.st_mode)) {
612 		fprintf(stderr, "File '%s' is not a directory\n", buf_dir_name);
613 		ret = -EFAULT;
614 		goto error;
615 	}
616 
617 	if (!notrigger) {
618 		printf("%s %s\n", dev_dir_name, trigger_name);
619 		/*
620 		 * Set the device trigger to be the data ready trigger found
621 		 * above
622 		 */
623 		ret = write_sysfs_string_and_verify("trigger/current_trigger",
624 						    dev_dir_name,
625 						    trigger_name);
626 		if (ret < 0) {
627 			fprintf(stderr,
628 				"Failed to write current_trigger file\n");
629 			goto error;
630 		}
631 	}
632 
633 	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
634 	if (ret < 0) {
635 		ret = -ENOMEM;
636 		goto error;
637 	}
638 
639 	/* Attempt to open non blocking the access dev */
640 	fd = open(buffer_access, O_RDONLY | O_NONBLOCK);
641 	if (fd == -1) { /* TODO: If it isn't there make the node */
642 		ret = -errno;
643 		fprintf(stderr, "Failed to open %s\n", buffer_access);
644 		goto error;
645 	}
646 
647 	/* specify for which buffer index we want an FD */
648 	buf_fd = buffer_idx;
649 
650 	ret = ioctl(fd, IIO_BUFFER_GET_FD_IOCTL, &buf_fd);
651 	if (ret == -1 || buf_fd == -1) {
652 		ret = -errno;
653 		if (ret == -ENODEV || ret == -EINVAL)
654 			fprintf(stderr,
655 				"Device does not have this many buffers\n");
656 		else
657 			fprintf(stderr, "Failed to retrieve buffer fd\n");
658 
659 		goto error;
660 	}
661 
662 	/* Setup ring buffer parameters */
663 	ret = write_sysfs_int("length", buf_dir_name, buf_len);
664 	if (ret < 0)
665 		goto error;
666 
667 	/* Enable the buffer */
668 	ret = write_sysfs_int("enable", buf_dir_name, 1);
669 	if (ret < 0) {
670 		fprintf(stderr,
671 			"Failed to enable buffer '%s': %s\n",
672 			buf_dir_name, strerror(-ret));
673 		goto error;
674 	}
675 
676 	scan_size = size_from_channelarray(channels, num_channels);
677 
678 	size_t total_buf_len = scan_size * buf_len;
679 
680 	if (scan_size > 0 && total_buf_len / scan_size != buf_len) {
681 		ret = -EFAULT;
682 		perror("Integer overflow happened when calculate scan_size * buf_len");
683 		goto error;
684 	}
685 
686 	data = malloc(total_buf_len);
687 	if (!data) {
688 		ret = -ENOMEM;
689 		goto error;
690 	}
691 
692 	/**
693 	 * This check is being done here for sanity reasons, however it
694 	 * should be omitted under normal operation.
695 	 * If this is buffer0, we check that we get EBUSY after this point.
696 	 */
697 	if (buffer_idx == 0) {
698 		errno = 0;
699 		read_size = read(fd, data, 1);
700 		if (read_size > -1 || errno != EBUSY) {
701 			ret = -EFAULT;
702 			perror("Reading from '%s' should not be possible after ioctl()");
703 			goto error;
704 		}
705 	}
706 
707 	/* close now the main chardev FD and let the buffer FD work */
708 	if (close(fd) == -1)
709 		perror("Failed to close character device file");
710 	fd = -1;
711 
712 	for (j = 0; j < num_loops || num_loops < 0; j++) {
713 		if (!noevents) {
714 			struct pollfd pfd = {
715 				.fd = buf_fd,
716 				.events = POLLIN,
717 			};
718 
719 			ret = poll(&pfd, 1, -1);
720 			if (ret < 0) {
721 				ret = -errno;
722 				goto error;
723 			} else if (ret == 0) {
724 				continue;
725 			}
726 
727 		} else {
728 			usleep(timedelay);
729 		}
730 
731 		toread = buf_len;
732 
733 		read_size = read(buf_fd, data, toread * scan_size);
734 		if (read_size < 0) {
735 			if (errno == EAGAIN) {
736 				fprintf(stderr, "nothing available\n");
737 				continue;
738 			} else {
739 				break;
740 			}
741 		}
742 		for (i = 0; i < read_size / scan_size; i++)
743 			process_scan(data + scan_size * i, channels,
744 				     num_channels);
745 	}
746 
747 error:
748 	cleanup();
749 
750 	if (fd >= 0 && close(fd) == -1)
751 		perror("Failed to close character device");
752 	if (buf_fd >= 0 && close(buf_fd) == -1)
753 		perror("Failed to close buffer");
754 	free(buffer_access);
755 	free(data);
756 	free(buf_dir_name);
757 	for (i = num_channels - 1; i >= 0; i--) {
758 		free(channels[i].name);
759 		free(channels[i].generic_name);
760 	}
761 	free(channels);
762 	free(trigger_name);
763 	free(device_name);
764 	free(dev_dir_name);
765 
766 	return ret;
767 }
768