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, max = 0;
58 	unsigned int misalignment;
59 
60 	while (i < num_channels) {
61 		if (channels[i].bytes > max)
62 			max = channels[i].bytes;
63 		if (bytes % channels[i].bytes == 0)
64 			channels[i].location = bytes;
65 		else
66 			channels[i].location = bytes - bytes % channels[i].bytes
67 					       + channels[i].bytes;
68 
69 		bytes = channels[i].location + channels[i].bytes;
70 		i++;
71 	}
72 	/*
73 	 * We want the data in next sample to also be properly aligned so
74 	 * we'll add padding at the end if needed. Adding padding only
75 	 * works for channel data which size is 2^n bytes.
76 	 */
77 	misalignment = bytes % max;
78 	if (misalignment)
79 		bytes += max - misalignment;
80 
81 	return bytes;
82 }
83 
84 static void print1byte(uint8_t input, struct iio_channel_info *info)
85 {
86 	/*
87 	 * Shift before conversion to avoid sign extension
88 	 * of left aligned data
89 	 */
90 	input >>= info->shift;
91 	input &= info->mask;
92 	if (info->is_signed) {
93 		int8_t val = (int8_t)(input << (8 - info->bits_used)) >>
94 			     (8 - info->bits_used);
95 		printf("%05f ", ((float)val + info->offset) * info->scale);
96 	} else {
97 		printf("%05f ", ((float)input + info->offset) * info->scale);
98 	}
99 }
100 
101 static void print2byte(uint16_t input, struct iio_channel_info *info)
102 {
103 	/* First swap if incorrect endian */
104 	if (info->be)
105 		input = be16toh(input);
106 	else
107 		input = le16toh(input);
108 
109 	/*
110 	 * Shift before conversion to avoid sign extension
111 	 * of left aligned data
112 	 */
113 	input >>= info->shift;
114 	input &= info->mask;
115 	if (info->is_signed) {
116 		int16_t val = (int16_t)(input << (16 - info->bits_used)) >>
117 			      (16 - info->bits_used);
118 		printf("%05f ", ((float)val + info->offset) * info->scale);
119 	} else {
120 		printf("%05f ", ((float)input + info->offset) * info->scale);
121 	}
122 }
123 
124 static void print4byte(uint32_t input, struct iio_channel_info *info)
125 {
126 	/* First swap if incorrect endian */
127 	if (info->be)
128 		input = be32toh(input);
129 	else
130 		input = le32toh(input);
131 
132 	/*
133 	 * Shift before conversion to avoid sign extension
134 	 * of left aligned data
135 	 */
136 	input >>= info->shift;
137 	input &= info->mask;
138 	if (info->is_signed) {
139 		int32_t val = (int32_t)(input << (32 - info->bits_used)) >>
140 			      (32 - info->bits_used);
141 		printf("%05f ", ((float)val + info->offset) * info->scale);
142 	} else {
143 		printf("%05f ", ((float)input + info->offset) * info->scale);
144 	}
145 }
146 
147 static void print8byte(uint64_t input, struct iio_channel_info *info)
148 {
149 	/* First swap if incorrect endian */
150 	if (info->be)
151 		input = be64toh(input);
152 	else
153 		input = le64toh(input);
154 
155 	/*
156 	 * Shift before conversion to avoid sign extension
157 	 * of left aligned data
158 	 */
159 	input >>= info->shift;
160 	input &= info->mask;
161 	if (info->is_signed) {
162 		int64_t val = (int64_t)(input << (64 - info->bits_used)) >>
163 			      (64 - info->bits_used);
164 		/* special case for timestamp */
165 		if (info->scale == 1.0f && info->offset == 0.0f)
166 			printf("%" PRId64 " ", val);
167 		else
168 			printf("%05f ",
169 			       ((float)val + info->offset) * info->scale);
170 	} else {
171 		printf("%05f ", ((float)input + info->offset) * info->scale);
172 	}
173 }
174 
175 /**
176  * process_scan() - print out the values in SI units
177  * @data:		pointer to the start of the scan
178  * @channels:		information about the channels.
179  *			Note: size_from_channelarray must have been called first
180  *			      to fill the location offsets.
181  * @num_channels:	number of channels
182  **/
183 static void process_scan(char *data, struct iio_channel_info *channels,
184 			 int num_channels)
185 {
186 	int k;
187 
188 	for (k = 0; k < num_channels; k++)
189 		switch (channels[k].bytes) {
190 			/* only a few cases implemented so far */
191 		case 1:
192 			print1byte(*(uint8_t *)(data + channels[k].location),
193 				   &channels[k]);
194 			break;
195 		case 2:
196 			print2byte(*(uint16_t *)(data + channels[k].location),
197 				   &channels[k]);
198 			break;
199 		case 4:
200 			print4byte(*(uint32_t *)(data + channels[k].location),
201 				   &channels[k]);
202 			break;
203 		case 8:
204 			print8byte(*(uint64_t *)(data + channels[k].location),
205 				   &channels[k]);
206 			break;
207 		default:
208 			break;
209 		}
210 	printf("\n");
211 }
212 
213 static int enable_disable_all_channels(char *dev_dir_name, int buffer_idx, int enable)
214 {
215 	const struct dirent *ent;
216 	char scanelemdir[256];
217 	DIR *dp;
218 	int ret;
219 
220 	snprintf(scanelemdir, sizeof(scanelemdir),
221 		 FORMAT_SCAN_ELEMENTS_DIR, dev_dir_name, buffer_idx);
222 	scanelemdir[sizeof(scanelemdir)-1] = '\0';
223 
224 	dp = opendir(scanelemdir);
225 	if (!dp) {
226 		fprintf(stderr, "Enabling/disabling channels: can't open %s\n",
227 			scanelemdir);
228 		return -EIO;
229 	}
230 
231 	ret = -ENOENT;
232 	while (ent = readdir(dp), ent) {
233 		if (iioutils_check_suffix(ent->d_name, "_en")) {
234 			printf("%sabling: %s\n",
235 			       enable ? "En" : "Dis",
236 			       ent->d_name);
237 			ret = write_sysfs_int(ent->d_name, scanelemdir,
238 					      enable);
239 			if (ret < 0)
240 				fprintf(stderr, "Failed to enable/disable %s\n",
241 					ent->d_name);
242 		}
243 	}
244 
245 	if (closedir(dp) == -1) {
246 		perror("Enabling/disabling channels: "
247 		       "Failed to close directory");
248 		return -errno;
249 	}
250 	return 0;
251 }
252 
253 static void print_usage(void)
254 {
255 	fprintf(stderr, "Usage: generic_buffer [options]...\n"
256 		"Capture, convert and output data from IIO device buffer\n"
257 		"  -a         Auto-activate all available channels\n"
258 		"  -A         Force-activate ALL channels\n"
259 		"  -b <n>     The buffer which to open (by index), default 0\n"
260 		"  -c <n>     Do n conversions, or loop forever if n < 0\n"
261 		"  -e         Disable wait for event (new data)\n"
262 		"  -g         Use trigger-less mode\n"
263 		"  -l <n>     Set buffer length to n samples\n"
264 		"  --device-name -n <name>\n"
265 		"  --device-num -N <num>\n"
266 		"        Set device by name or number (mandatory)\n"
267 		"  --trigger-name -t <name>\n"
268 		"  --trigger-num -T <num>\n"
269 		"        Set trigger by name or number\n"
270 		"  -w <n>     Set delay between reads in us (event-less mode)\n");
271 }
272 
273 static enum autochan autochannels = AUTOCHANNELS_DISABLED;
274 static char *dev_dir_name = NULL;
275 static char *buf_dir_name = NULL;
276 static int buffer_idx = 0;
277 static bool current_trigger_set = false;
278 
279 static void cleanup(void)
280 {
281 	int ret;
282 
283 	/* Disable trigger */
284 	if (dev_dir_name && current_trigger_set) {
285 		/* Disconnect the trigger - just write a dummy name. */
286 		ret = write_sysfs_string("trigger/current_trigger",
287 					 dev_dir_name, "NULL");
288 		if (ret < 0)
289 			fprintf(stderr, "Failed to disable trigger: %s\n",
290 				strerror(-ret));
291 		current_trigger_set = false;
292 	}
293 
294 	/* Disable buffer */
295 	if (buf_dir_name) {
296 		ret = write_sysfs_int("enable", buf_dir_name, 0);
297 		if (ret < 0)
298 			fprintf(stderr, "Failed to disable buffer: %s\n",
299 				strerror(-ret));
300 	}
301 
302 	/* Disable channels if auto-enabled */
303 	if (dev_dir_name && autochannels == AUTOCHANNELS_ACTIVE) {
304 		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 0);
305 		if (ret)
306 			fprintf(stderr, "Failed to disable all channels\n");
307 		autochannels = AUTOCHANNELS_DISABLED;
308 	}
309 }
310 
311 static void sig_handler(int signum)
312 {
313 	fprintf(stderr, "Caught signal %d\n", signum);
314 	cleanup();
315 	exit(-signum);
316 }
317 
318 static void register_cleanup(void)
319 {
320 	struct sigaction sa = { .sa_handler = sig_handler };
321 	const int signums[] = { SIGINT, SIGTERM, SIGABRT };
322 	int ret, i;
323 
324 	for (i = 0; i < ARRAY_SIZE(signums); ++i) {
325 		ret = sigaction(signums[i], &sa, NULL);
326 		if (ret) {
327 			perror("Failed to register signal handler");
328 			exit(-1);
329 		}
330 	}
331 }
332 
333 static const struct option longopts[] = {
334 	{ "device-name",	1, 0, 'n' },
335 	{ "device-num",		1, 0, 'N' },
336 	{ "trigger-name",	1, 0, 't' },
337 	{ "trigger-num",	1, 0, 'T' },
338 	{ },
339 };
340 
341 int main(int argc, char **argv)
342 {
343 	long long num_loops = 2;
344 	unsigned long timedelay = 1000000;
345 	unsigned long buf_len = 128;
346 
347 	ssize_t i;
348 	unsigned long long j;
349 	unsigned long toread;
350 	int ret, c;
351 	struct stat st;
352 	int fd = -1;
353 	int buf_fd = -1;
354 
355 	int num_channels = 0;
356 	char *trigger_name = NULL, *device_name = NULL;
357 
358 	char *data = NULL;
359 	ssize_t read_size;
360 	int dev_num = -1, trig_num = -1;
361 	char *buffer_access = NULL;
362 	unsigned int scan_size;
363 	int noevents = 0;
364 	int notrigger = 0;
365 	char *dummy;
366 	bool force_autochannels = false;
367 
368 	struct iio_channel_info *channels = NULL;
369 
370 	register_cleanup();
371 
372 	while ((c = getopt_long(argc, argv, "aAb:c:egl:n:N:t:T:w:?", longopts,
373 				NULL)) != -1) {
374 		switch (c) {
375 		case 'a':
376 			autochannels = AUTOCHANNELS_ENABLED;
377 			break;
378 		case 'A':
379 			autochannels = AUTOCHANNELS_ENABLED;
380 			force_autochannels = true;
381 			break;
382 		case 'b':
383 			errno = 0;
384 			buffer_idx = strtoll(optarg, &dummy, 10);
385 			if (errno) {
386 				ret = -errno;
387 				goto error;
388 			}
389 			if (buffer_idx < 0) {
390 				ret = -ERANGE;
391 				goto error;
392 			}
393 
394 			break;
395 		case 'c':
396 			errno = 0;
397 			num_loops = strtoll(optarg, &dummy, 10);
398 			if (errno) {
399 				ret = -errno;
400 				goto error;
401 			}
402 
403 			break;
404 		case 'e':
405 			noevents = 1;
406 			break;
407 		case 'g':
408 			notrigger = 1;
409 			break;
410 		case 'l':
411 			errno = 0;
412 			buf_len = strtoul(optarg, &dummy, 10);
413 			if (errno) {
414 				ret = -errno;
415 				goto error;
416 			}
417 
418 			break;
419 		case 'n':
420 			device_name = strdup(optarg);
421 			break;
422 		case 'N':
423 			errno = 0;
424 			dev_num = strtoul(optarg, &dummy, 10);
425 			if (errno) {
426 				ret = -errno;
427 				goto error;
428 			}
429 			break;
430 		case 't':
431 			trigger_name = strdup(optarg);
432 			break;
433 		case 'T':
434 			errno = 0;
435 			trig_num = strtoul(optarg, &dummy, 10);
436 			if (errno)
437 				return -errno;
438 			break;
439 		case 'w':
440 			errno = 0;
441 			timedelay = strtoul(optarg, &dummy, 10);
442 			if (errno) {
443 				ret = -errno;
444 				goto error;
445 			}
446 			break;
447 		case '?':
448 			print_usage();
449 			ret = -1;
450 			goto error;
451 		}
452 	}
453 
454 	/* Find the device requested */
455 	if (dev_num < 0 && !device_name) {
456 		fprintf(stderr, "Device not set\n");
457 		print_usage();
458 		ret = -1;
459 		goto error;
460 	} else if (dev_num >= 0 && device_name) {
461 		fprintf(stderr, "Only one of --device-num or --device-name needs to be set\n");
462 		print_usage();
463 		ret = -1;
464 		goto error;
465 	} else if (dev_num < 0) {
466 		dev_num = find_type_by_name(device_name, "iio:device");
467 		if (dev_num < 0) {
468 			fprintf(stderr, "Failed to find the %s\n", device_name);
469 			ret = dev_num;
470 			goto error;
471 		}
472 	}
473 	printf("iio device number being used is %d\n", dev_num);
474 
475 	ret = asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
476 	if (ret < 0)
477 		return -ENOMEM;
478 	/* Fetch device_name if specified by number */
479 	if (!device_name) {
480 		device_name = malloc(IIO_MAX_NAME_LENGTH);
481 		if (!device_name) {
482 			ret = -ENOMEM;
483 			goto error;
484 		}
485 		ret = read_sysfs_string("name", dev_dir_name, device_name);
486 		if (ret < 0) {
487 			fprintf(stderr, "Failed to read name of device %d\n", dev_num);
488 			goto error;
489 		}
490 	}
491 
492 	if (notrigger) {
493 		printf("trigger-less mode selected\n");
494 	} else if (trig_num >= 0) {
495 		char *trig_dev_name;
496 		ret = asprintf(&trig_dev_name, "%strigger%d", iio_dir, trig_num);
497 		if (ret < 0) {
498 			return -ENOMEM;
499 		}
500 		trigger_name = malloc(IIO_MAX_NAME_LENGTH);
501 		ret = read_sysfs_string("name", trig_dev_name, trigger_name);
502 		free(trig_dev_name);
503 		if (ret < 0) {
504 			fprintf(stderr, "Failed to read trigger%d name from\n", trig_num);
505 			return ret;
506 		}
507 		printf("iio trigger number being used is %d\n", trig_num);
508 	} else {
509 		if (!trigger_name) {
510 			/*
511 			 * Build the trigger name. If it is device associated
512 			 * its name is <device_name>_dev[n] where n matches
513 			 * the device number found above.
514 			 */
515 			ret = asprintf(&trigger_name,
516 				       "%s-dev%d", device_name, dev_num);
517 			if (ret < 0) {
518 				ret = -ENOMEM;
519 				goto error;
520 			}
521 		}
522 
523 		/* Look for this "-devN" trigger */
524 		trig_num = find_type_by_name(trigger_name, "trigger");
525 		if (trig_num < 0) {
526 			/* OK try the simpler "-trigger" suffix instead */
527 			free(trigger_name);
528 			ret = asprintf(&trigger_name,
529 				       "%s-trigger", device_name);
530 			if (ret < 0) {
531 				ret = -ENOMEM;
532 				goto error;
533 			}
534 		}
535 
536 		trig_num = find_type_by_name(trigger_name, "trigger");
537 		if (trig_num < 0) {
538 			fprintf(stderr, "Failed to find the trigger %s\n",
539 				trigger_name);
540 			ret = trig_num;
541 			goto error;
542 		}
543 
544 		printf("iio trigger number being used is %d\n", trig_num);
545 	}
546 
547 	/*
548 	 * Parse the files in scan_elements to identify what channels are
549 	 * present
550 	 */
551 	ret = build_channel_array(dev_dir_name, buffer_idx, &channels, &num_channels);
552 	if (ret) {
553 		fprintf(stderr, "Problem reading scan element information\n"
554 			"diag %s\n", dev_dir_name);
555 		goto error;
556 	}
557 	if (num_channels && autochannels == AUTOCHANNELS_ENABLED &&
558 	    !force_autochannels) {
559 		fprintf(stderr, "Auto-channels selected but some channels "
560 			"are already activated in sysfs\n");
561 		fprintf(stderr, "Proceeding without activating any channels\n");
562 	}
563 
564 	if ((!num_channels && autochannels == AUTOCHANNELS_ENABLED) ||
565 	    (autochannels == AUTOCHANNELS_ENABLED && force_autochannels)) {
566 		fprintf(stderr, "Enabling all channels\n");
567 
568 		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 1);
569 		if (ret) {
570 			fprintf(stderr, "Failed to enable all channels\n");
571 			goto error;
572 		}
573 
574 		/* This flags that we need to disable the channels again */
575 		autochannels = AUTOCHANNELS_ACTIVE;
576 
577 		ret = build_channel_array(dev_dir_name, buffer_idx, &channels,
578 					  &num_channels);
579 		if (ret) {
580 			fprintf(stderr, "Problem reading scan element "
581 				"information\n"
582 				"diag %s\n", dev_dir_name);
583 			goto error;
584 		}
585 		if (!num_channels) {
586 			fprintf(stderr, "Still no channels after "
587 				"auto-enabling, giving up\n");
588 			goto error;
589 		}
590 	}
591 
592 	if (!num_channels && autochannels == AUTOCHANNELS_DISABLED) {
593 		fprintf(stderr,
594 			"No channels are enabled, we have nothing to scan.\n");
595 		fprintf(stderr, "Enable channels manually in "
596 			FORMAT_SCAN_ELEMENTS_DIR
597 			"/*_en or pass -a to autoenable channels and "
598 			"try again.\n", dev_dir_name, buffer_idx);
599 		ret = -ENOENT;
600 		goto error;
601 	}
602 
603 	/*
604 	 * Construct the directory name for the associated buffer.
605 	 * As we know that the lis3l02dq has only one buffer this may
606 	 * be built rather than found.
607 	 */
608 	ret = asprintf(&buf_dir_name,
609 		       "%siio:device%d/buffer%d", iio_dir, dev_num, buffer_idx);
610 	if (ret < 0) {
611 		ret = -ENOMEM;
612 		goto error;
613 	}
614 
615 	if (stat(buf_dir_name, &st)) {
616 		fprintf(stderr, "Could not stat() '%s', got error %d: %s\n",
617 			buf_dir_name, errno, strerror(errno));
618 		ret = -errno;
619 		goto error;
620 	}
621 
622 	if (!S_ISDIR(st.st_mode)) {
623 		fprintf(stderr, "File '%s' is not a directory\n", buf_dir_name);
624 		ret = -EFAULT;
625 		goto error;
626 	}
627 
628 	if (!notrigger) {
629 		printf("%s %s\n", dev_dir_name, trigger_name);
630 		/*
631 		 * Set the device trigger to be the data ready trigger found
632 		 * above
633 		 */
634 		ret = write_sysfs_string_and_verify("trigger/current_trigger",
635 						    dev_dir_name,
636 						    trigger_name);
637 		if (ret < 0) {
638 			fprintf(stderr,
639 				"Failed to write current_trigger file\n");
640 			goto error;
641 		}
642 	}
643 
644 	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
645 	if (ret < 0) {
646 		ret = -ENOMEM;
647 		goto error;
648 	}
649 
650 	/* Attempt to open non blocking the access dev */
651 	fd = open(buffer_access, O_RDONLY | O_NONBLOCK);
652 	if (fd == -1) { /* TODO: If it isn't there make the node */
653 		ret = -errno;
654 		fprintf(stderr, "Failed to open %s\n", buffer_access);
655 		goto error;
656 	}
657 
658 	/* specify for which buffer index we want an FD */
659 	buf_fd = buffer_idx;
660 
661 	ret = ioctl(fd, IIO_BUFFER_GET_FD_IOCTL, &buf_fd);
662 	if (ret == -1 || buf_fd == -1) {
663 		ret = -errno;
664 		if (ret == -ENODEV || ret == -EINVAL)
665 			fprintf(stderr,
666 				"Device does not have this many buffers\n");
667 		else
668 			fprintf(stderr, "Failed to retrieve buffer fd\n");
669 
670 		goto error;
671 	}
672 
673 	/* Setup ring buffer parameters */
674 	ret = write_sysfs_int("length", buf_dir_name, buf_len);
675 	if (ret < 0)
676 		goto error;
677 
678 	/* Enable the buffer */
679 	ret = write_sysfs_int("enable", buf_dir_name, 1);
680 	if (ret < 0) {
681 		fprintf(stderr,
682 			"Failed to enable buffer '%s': %s\n",
683 			buf_dir_name, strerror(-ret));
684 		goto error;
685 	}
686 
687 	scan_size = size_from_channelarray(channels, num_channels);
688 
689 	size_t total_buf_len = scan_size * buf_len;
690 
691 	if (scan_size > 0 && total_buf_len / scan_size != buf_len) {
692 		ret = -EFAULT;
693 		perror("Integer overflow happened when calculate scan_size * buf_len");
694 		goto error;
695 	}
696 
697 	data = malloc(total_buf_len);
698 	if (!data) {
699 		ret = -ENOMEM;
700 		goto error;
701 	}
702 
703 	/**
704 	 * This check is being done here for sanity reasons, however it
705 	 * should be omitted under normal operation.
706 	 * If this is buffer0, we check that we get EBUSY after this point.
707 	 */
708 	if (buffer_idx == 0) {
709 		errno = 0;
710 		read_size = read(fd, data, 1);
711 		if (read_size > -1 || errno != EBUSY) {
712 			ret = -EFAULT;
713 			perror("Reading from '%s' should not be possible after ioctl()");
714 			goto error;
715 		}
716 	}
717 
718 	/* close now the main chardev FD and let the buffer FD work */
719 	if (close(fd) == -1)
720 		perror("Failed to close character device file");
721 	fd = -1;
722 
723 	for (j = 0; j < num_loops || num_loops < 0; j++) {
724 		if (!noevents) {
725 			struct pollfd pfd = {
726 				.fd = buf_fd,
727 				.events = POLLIN,
728 			};
729 
730 			ret = poll(&pfd, 1, -1);
731 			if (ret < 0) {
732 				ret = -errno;
733 				goto error;
734 			} else if (ret == 0) {
735 				continue;
736 			}
737 
738 		} else {
739 			usleep(timedelay);
740 		}
741 
742 		toread = buf_len;
743 
744 		read_size = read(buf_fd, data, toread * scan_size);
745 		if (read_size < 0) {
746 			if (errno == EAGAIN) {
747 				fprintf(stderr, "nothing available\n");
748 				continue;
749 			} else {
750 				break;
751 			}
752 		}
753 		for (i = 0; i < read_size / scan_size; i++)
754 			process_scan(data + scan_size * i, channels,
755 				     num_channels);
756 	}
757 
758 error:
759 	cleanup();
760 
761 	if (fd >= 0 && close(fd) == -1)
762 		perror("Failed to close character device");
763 	if (buf_fd >= 0 && close(buf_fd) == -1)
764 		perror("Failed to close buffer");
765 	free(buffer_access);
766 	free(data);
767 	free(buf_dir_name);
768 	for (i = num_channels - 1; i >= 0; i--) {
769 		free(channels[i].name);
770 		free(channels[i].generic_name);
771 	}
772 	free(channels);
773 	free(trigger_name);
774 	free(device_name);
775 	free(dev_dir_name);
776 
777 	return ret;
778 }
779