iio_generic_buffer.c

// SPDX-License-Identifier: GPL-2.0-only
/* Industrialio buffer test code.
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is primarily intended as an example application.
 * Reads the current buffer setup from sysfs and starts a short capture
 * from the specified device, pretty printing the result after appropriate
 * conversion.
 *
 * Command line parameters
 * generic_buffer -n <device_name> -t <trigger_name>
 * If trigger name is not specified the program assumes you want a dataready
 * trigger associated with the device and goes looking for it.
 */

#include <unistd.h>
#include <stdlib.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/dir.h>
#include <linux/types.h>
#include <string.h>
#include <poll.h>
#include <endian.h>
#include <getopt.h>
#include <inttypes.h>
#include <stdbool.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <linux/iio/buffer.h>
#include "iio_utils.h"

/**
 * enum autochan - state for the automatic channel enabling mechanism
 */
enum autochan {
	AUTOCHANNELS_DISABLED,
	AUTOCHANNELS_ENABLED,
	AUTOCHANNELS_ACTIVE,
};

/**
 * size_from_channelarray() - calculate the storage size of a scan
 * @channels:		the channel info array
 * @num_channels:	number of channels
 *
 * Has the side effect of filling the channels[i].location values used
 * in processing the buffer output.
 **/
static int size_from_channelarray(struct iio_channel_info *channels, int num_channels)
{
	int bytes = 0;
	int i = 0;

	while (i < num_channels) {
		if (bytes % channels[i].bytes == 0)
			channels[i].location = bytes;
		else
			channels[i].location = bytes - bytes % channels[i].bytes
					       + channels[i].bytes;

		bytes = channels[i].location + channels[i].bytes;
		i++;
	}

	return bytes;
}

static void print1byte(uint8_t input, struct iio_channel_info *info)
{
	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int8_t val = (int8_t)(input << (8 - info->bits_used)) >>
			     (8 - info->bits_used);
		printf("%05f ", ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

static void print2byte(uint16_t input, struct iio_channel_info *info)
{
	/* First swap if incorrect endian */
	if (info->be)
		input = be16toh(input);
	else
		input = le16toh(input);

	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int16_t val = (int16_t)(input << (16 - info->bits_used)) >>
			      (16 - info->bits_used);
		printf("%05f ", ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

static void print4byte(uint32_t input, struct iio_channel_info *info)
{
	/* First swap if incorrect endian */
	if (info->be)
		input = be32toh(input);
	else
		input = le32toh(input);

	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int32_t val = (int32_t)(input << (32 - info->bits_used)) >>
			      (32 - info->bits_used);
		printf("%05f ", ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

static void print8byte(uint64_t input, struct iio_channel_info *info)
{
	/* First swap if incorrect endian */
	if (info->be)
		input = be64toh(input);
	else
		input = le64toh(input);

	/*
	 * Shift before conversion to avoid sign extension
	 * of left aligned data
	 */
	input >>= info->shift;
	input &= info->mask;
	if (info->is_signed) {
		int64_t val = (int64_t)(input << (64 - info->bits_used)) >>
			      (64 - info->bits_used);
		/* special case for timestamp */
		if (info->scale == 1.0f && info->offset == 0.0f)
			printf("%" PRId64 " ", val);
		else
			printf("%05f ",
			       ((float)val + info->offset) * info->scale);
	} else {
		printf("%05f ", ((float)input + info->offset) * info->scale);
	}
}

/**
 * process_scan() - print out the values in SI units
 * @data:		pointer to the start of the scan
 * @channels:		information about the channels.
 *			Note: size_from_channelarray must have been called first
 *			      to fill the location offsets.
 * @num_channels:	number of channels
 **/
static void process_scan(char *data, struct iio_channel_info *channels,
			 int num_channels)
{
	int k;

	for (k = 0; k < num_channels; k++)
		switch (channels[k].bytes) {
			/* only a few cases implemented so far */
		case 1:
			print1byte(*(uint8_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		case 2:
			print2byte(*(uint16_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		case 4:
			print4byte(*(uint32_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		case 8:
			print8byte(*(uint64_t *)(data + channels[k].location),
				   &channels[k]);
			break;
		default:
			break;
		}
	printf("\n");
}

static int enable_disable_all_channels(char *dev_dir_name, int buffer_idx, int enable)
{
	const struct dirent *ent;
	char scanelemdir[256];
	DIR *dp;
	int ret;

	snprintf(scanelemdir, sizeof(scanelemdir),
		 FORMAT_SCAN_ELEMENTS_DIR, dev_dir_name, buffer_idx);
	scanelemdir[sizeof(scanelemdir)-1] = '\0';

	dp = opendir(scanelemdir);
	if (!dp) {
		fprintf(stderr, "Enabling/disabling channels: can't open %s\n",
			scanelemdir);
		return -EIO;
	}

	ret = -ENOENT;
	while (ent = readdir(dp), ent) {
		if (iioutils_check_suffix(ent->d_name, "_en")) {
			printf("%sabling: %s\n",
			       enable ? "En" : "Dis",
			       ent->d_name);
			ret = write_sysfs_int(ent->d_name, scanelemdir,
					      enable);
			if (ret < 0)
				fprintf(stderr, "Failed to enable/disable %s\n",
					ent->d_name);
		}
	}

	if (closedir(dp) == -1) {
		perror("Enabling/disabling channels: "
		       "Failed to close directory");
		return -errno;
	}
	return 0;
}

static void print_usage(void)
{
	fprintf(stderr, "Usage: generic_buffer [options]...\n"
		"Capture, convert and output data from IIO device buffer\n"
		"  -a         Auto-activate all available channels\n"
		"  -A         Force-activate ALL channels\n"
		"  -b <n>     The buffer which to open (by index), default 0\n"
		"  -c <n>     Do n conversions, or loop forever if n < 0\n"
		"  -e         Disable wait for event (new data)\n"
		"  -g         Use trigger-less mode\n"
		"  -l <n>     Set buffer length to n samples\n"
		"  --device-name -n <name>\n"
		"  --device-num -N <num>\n"
		"        Set device by name or number (mandatory)\n"
		"  --trigger-name -t <name>\n"
		"  --trigger-num -T <num>\n"
		"        Set trigger by name or number\n"
		"  -w <n>     Set delay between reads in us (event-less mode)\n");
}

static enum autochan autochannels = AUTOCHANNELS_DISABLED;
static char *dev_dir_name = NULL;
static char *buf_dir_name = NULL;
static int buffer_idx = 0;
static bool current_trigger_set = false;

static void cleanup(void)
{
	int ret;

	/* Disable trigger */
	if (dev_dir_name && current_trigger_set) {
		/* Disconnect the trigger - just write a dummy name. */
		ret = write_sysfs_string("trigger/current_trigger",
					 dev_dir_name, "NULL");
		if (ret < 0)
			fprintf(stderr, "Failed to disable trigger: %s\n",
				strerror(-ret));
		current_trigger_set = false;
	}

	/* Disable buffer */
	if (buf_dir_name) {
		ret = write_sysfs_int("enable", buf_dir_name, 0);
		if (ret < 0)
			fprintf(stderr, "Failed to disable buffer: %s\n",
				strerror(-ret));
	}

	/* Disable channels if auto-enabled */
	if (dev_dir_name && autochannels == AUTOCHANNELS_ACTIVE) {
		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 0);
		if (ret)
			fprintf(stderr, "Failed to disable all channels\n");
		autochannels = AUTOCHANNELS_DISABLED;
	}
}

static void sig_handler(int signum)
{
	fprintf(stderr, "Caught signal %d\n", signum);
	cleanup();
	exit(-signum);
}

static void register_cleanup(void)
{
	struct sigaction sa = { .sa_handler = sig_handler };
	const int signums[] = { SIGINT, SIGTERM, SIGABRT };
	int ret, i;

	for (i = 0; i < ARRAY_SIZE(signums); ++i) {
		ret = sigaction(signums[i], &sa, NULL);
		if (ret) {
			perror("Failed to register signal handler");
			exit(-1);
		}
	}
}

static const struct option longopts[] = {
	{ "device-name",	1, 0, 'n' },
	{ "device-num",		1, 0, 'N' },
	{ "trigger-name",	1, 0, 't' },
	{ "trigger-num",	1, 0, 'T' },
	{ },
};

int main(int argc, char **argv)
{
	long long num_loops = 2;
	unsigned long timedelay = 1000000;
	unsigned long buf_len = 128;

	ssize_t i;
	unsigned long long j;
	unsigned long toread;
	int ret, c;
	struct stat st;
	int fd = -1;
	int buf_fd = -1;

	int num_channels = 0;
	char *trigger_name = NULL, *device_name = NULL;

	char *data = NULL;
	ssize_t read_size;
	int dev_num = -1, trig_num = -1;
	char *buffer_access = NULL;
	int scan_size;
	int noevents = 0;
	int notrigger = 0;
	char *dummy;
	bool force_autochannels = false;

	struct iio_channel_info *channels = NULL;

	register_cleanup();

	while ((c = getopt_long(argc, argv, "aAb:c:egl:n:N:t:T:w:?", longopts,
				NULL)) != -1) {
		switch (c) {
		case 'a':
			autochannels = AUTOCHANNELS_ENABLED;
			break;
		case 'A':
			autochannels = AUTOCHANNELS_ENABLED;
			force_autochannels = true;
			break;
		case 'b':
			errno = 0;
			buffer_idx = strtoll(optarg, &dummy, 10);
			if (errno) {
				ret = -errno;
				goto error;
			}
			if (buffer_idx < 0) {
				ret = -ERANGE;
				goto error;
			}

			break;
		case 'c':
			errno = 0;
			num_loops = strtoll(optarg, &dummy, 10);
			if (errno) {
				ret = -errno;
				goto error;
			}

			break;
		case 'e':
			noevents = 1;
			break;
		case 'g':
			notrigger = 1;
			break;
		case 'l':
			errno = 0;
			buf_len = strtoul(optarg, &dummy, 10);
			if (errno) {
				ret = -errno;
				goto error;
			}

			break;
		case 'n':
			device_name = strdup(optarg);
			break;
		case 'N':
			errno = 0;
			dev_num = strtoul(optarg, &dummy, 10);
			if (errno) {
				ret = -errno;
				goto error;
			}
			break;
		case 't':
			trigger_name = strdup(optarg);
			break;
		case 'T':
			errno = 0;
			trig_num = strtoul(optarg, &dummy, 10);
			if (errno)
				return -errno;
			break;
		case 'w':
			errno = 0;
			timedelay = strtoul(optarg, &dummy, 10);
			if (errno) {
				ret = -errno;
				goto error;
			}
			break;
		case '?':
			print_usage();
			ret = -1;
			goto error;
		}
	}

	/* Find the device requested */
	if (dev_num < 0 && !device_name) {
		fprintf(stderr, "Device not set\n");
		print_usage();
		ret = -1;
		goto error;
	} else if (dev_num >= 0 && device_name) {
		fprintf(stderr, "Only one of --device-num or --device-name needs to be set\n");
		print_usage();
		ret = -1;
		goto error;
	} else if (dev_num < 0) {
		dev_num = find_type_by_name(device_name, "iio:device");
		if (dev_num < 0) {
			fprintf(stderr, "Failed to find the %s\n", device_name);
			ret = dev_num;
			goto error;
		}
	}
	printf("iio device number being used is %d\n", dev_num);

	ret = asprintf(&dev_dir_name, "%siio:device%d", iio_dir, dev_num);
	if (ret < 0)
		return -ENOMEM;
	/* Fetch device_name if specified by number */
	if (!device_name) {
		device_name = malloc(IIO_MAX_NAME_LENGTH);
		if (!device_name) {
			ret = -ENOMEM;
			goto error;
		}
		ret = read_sysfs_string("name", dev_dir_name, device_name);
		if (ret < 0) {
			fprintf(stderr, "Failed to read name of device %d\n", dev_num);
			goto error;
		}
	}

	if (notrigger) {
		printf("trigger-less mode selected\n");
	} else if (trig_num >= 0) {
		char *trig_dev_name;
		ret = asprintf(&trig_dev_name, "%strigger%d", iio_dir, trig_num);
		if (ret < 0) {
			return -ENOMEM;
		}
		trigger_name = malloc(IIO_MAX_NAME_LENGTH);
		ret = read_sysfs_string("name", trig_dev_name, trigger_name);
		free(trig_dev_name);
		if (ret < 0) {
			fprintf(stderr, "Failed to read trigger%d name from\n", trig_num);
			return ret;
		}
		printf("iio trigger number being used is %d\n", trig_num);
	} else {
		if (!trigger_name) {
			/*
			 * Build the trigger name. If it is device associated
			 * its name is <device_name>_dev[n] where n matches
			 * the device number found above.
			 */
			ret = asprintf(&trigger_name,
				       "%s-dev%d", device_name, dev_num);
			if (ret < 0) {
				ret = -ENOMEM;
				goto error;
			}
		}

		/* Look for this "-devN" trigger */
		trig_num = find_type_by_name(trigger_name, "trigger");
		if (trig_num < 0) {
			/* OK try the simpler "-trigger" suffix instead */
			free(trigger_name);
			ret = asprintf(&trigger_name,
				       "%s-trigger", device_name);
			if (ret < 0) {
				ret = -ENOMEM;
				goto error;
			}
		}

		trig_num = find_type_by_name(trigger_name, "trigger");
		if (trig_num < 0) {
			fprintf(stderr, "Failed to find the trigger %s\n",
				trigger_name);
			ret = trig_num;
			goto error;
		}

		printf("iio trigger number being used is %d\n", trig_num);
	}

	/*
	 * Parse the files in scan_elements to identify what channels are
	 * present
	 */
	ret = build_channel_array(dev_dir_name, buffer_idx, &channels, &num_channels);
	if (ret) {
		fprintf(stderr, "Problem reading scan element information\n"
			"diag %s\n", dev_dir_name);
		goto error;
	}
	if (num_channels && autochannels == AUTOCHANNELS_ENABLED &&
	    !force_autochannels) {
		fprintf(stderr, "Auto-channels selected but some channels "
			"are already activated in sysfs\n");
		fprintf(stderr, "Proceeding without activating any channels\n");
	}

	if ((!num_channels && autochannels == AUTOCHANNELS_ENABLED) ||
	    (autochannels == AUTOCHANNELS_ENABLED && force_autochannels)) {
		fprintf(stderr, "Enabling all channels\n");

		ret = enable_disable_all_channels(dev_dir_name, buffer_idx, 1);
		if (ret) {
			fprintf(stderr, "Failed to enable all channels\n");
			goto error;
		}

		/* This flags that we need to disable the channels again */
		autochannels = AUTOCHANNELS_ACTIVE;

		ret = build_channel_array(dev_dir_name, buffer_idx, &channels,
					  &num_channels);
		if (ret) {
			fprintf(stderr, "Problem reading scan element "
				"information\n"
				"diag %s\n", dev_dir_name);
			goto error;
		}
		if (!num_channels) {
			fprintf(stderr, "Still no channels after "
				"auto-enabling, giving up\n");
			goto error;
		}
	}

	if (!num_channels && autochannels == AUTOCHANNELS_DISABLED) {
		fprintf(stderr,
			"No channels are enabled, we have nothing to scan.\n");
		fprintf(stderr, "Enable channels manually in "
			FORMAT_SCAN_ELEMENTS_DIR
			"/*_en or pass -a to autoenable channels and "
			"try again.\n", dev_dir_name, buffer_idx);
		ret = -ENOENT;
		goto error;
	}

	/*
	 * Construct the directory name for the associated buffer.
	 * As we know that the lis3l02dq has only one buffer this may
	 * be built rather than found.
	 */
	ret = asprintf(&buf_dir_name,
		       "%siio:device%d/buffer%d", iio_dir, dev_num, buffer_idx);
	if (ret < 0) {
		ret = -ENOMEM;
		goto error;
	}

	if (stat(buf_dir_name, &st)) {
		fprintf(stderr, "Could not stat() '%s', got error %d: %s\n",
			buf_dir_name, errno, strerror(errno));
		ret = -errno;
		goto error;
	}

	if (!S_ISDIR(st.st_mode)) {
		fprintf(stderr, "File '%s' is not a directory\n", buf_dir_name);
		ret = -EFAULT;
		goto error;
	}

	if (!notrigger) {
		printf("%s %s\n", dev_dir_name, trigger_name);
		/*
		 * Set the device trigger to be the data ready trigger found
		 * above
		 */
		ret = write_sysfs_string_and_verify("trigger/current_trigger",
						    dev_dir_name,
						    trigger_name);
		if (ret < 0) {
			fprintf(stderr,
				"Failed to write current_trigger file\n");
			goto error;
		}
	}

	ret = asprintf(&buffer_access, "/dev/iio:device%d", dev_num);
	if (ret < 0) {
		ret = -ENOMEM;
		goto error;
	}

	/* Attempt to open non blocking the access dev */
	fd = open(buffer_access, O_RDONLY | O_NONBLOCK);
	if (fd == -1) { /* TODO: If it isn't there make the node */
		ret = -errno;
		fprintf(stderr, "Failed to open %s\n", buffer_access);
		goto error;
	}

	/* specify for which buffer index we want an FD */
	buf_fd = buffer_idx;

	ret = ioctl(fd, IIO_BUFFER_GET_FD_IOCTL, &buf_fd);
	if (ret == -1 || buf_fd == -1) {
		ret = -errno;
		if (ret == -ENODEV || ret == -EINVAL)
			fprintf(stderr,
				"Device does not have this many buffers\n");
		else
			fprintf(stderr, "Failed to retrieve buffer fd\n");

		goto error;
	}

	/* Setup ring buffer parameters */
	ret = write_sysfs_int("length", buf_dir_name, buf_len);
	if (ret < 0)
		goto error;

	/* Enable the buffer */
	ret = write_sysfs_int("enable", buf_dir_name, 1);
	if (ret < 0) {
		fprintf(stderr,
			"Failed to enable buffer '%s': %s\n",
			buf_dir_name, strerror(-ret));
		goto error;
	}

	scan_size = size_from_channelarray(channels, num_channels);
	data = malloc(scan_size * buf_len);
	if (!data) {
		ret = -ENOMEM;
		goto error;
	}

	/**
	 * This check is being done here for sanity reasons, however it
	 * should be omitted under normal operation.
	 * If this is buffer0, we check that we get EBUSY after this point.
	 */
	if (buffer_idx == 0) {
		errno = 0;
		read_size = read(fd, data, 1);
		if (read_size > -1 || errno != EBUSY) {
			ret = -EFAULT;
			perror("Reading from '%s' should not be possible after ioctl()");
			goto error;
		}
	}

	/* close now the main chardev FD and let the buffer FD work */
	if (close(fd) == -1)
		perror("Failed to close character device file");
	fd = -1;

	for (j = 0; j < num_loops || num_loops < 0; j++) {
		if (!noevents) {
			struct pollfd pfd = {
				.fd = buf_fd,
				.events = POLLIN,
			};

			ret = poll(&pfd, 1, -1);
			if (ret < 0) {
				ret = -errno;
				goto error;
			} else if (ret == 0) {
				continue;
			}

			toread = buf_len;
		} else {
			usleep(timedelay);
			toread = 64;
		}

		read_size = read(buf_fd, data, toread * scan_size);
		if (read_size < 0) {
			if (errno == EAGAIN) {
				fprintf(stderr, "nothing available\n");
				continue;
			} else {
				break;
			}
		}
		for (i = 0; i < read_size / scan_size; i++)
			process_scan(data + scan_size * i, channels,
				     num_channels);
	}

error:
	cleanup();

	if (fd >= 0 && close(fd) == -1)
		perror("Failed to close character device");
	if (buf_fd >= 0 && close(buf_fd) == -1)
		perror("Failed to close buffer");
	free(buffer_access);
	free(data);
	free(buf_dir_name);
	for (i = num_channels - 1; i >= 0; i--) {
		free(channels[i].name);
		free(channels[i].generic_name);
	}
	free(channels);
	free(trigger_name);
	free(device_name);
	free(dev_dir_name);

	return ret;
}