path: root/tools/iio/iio_utils.c

// SPDX-License-Identifier: GPL-2.0-only
/* IIO - useful set of util functionality
 *
 * Copyright (c) 2008 Jonathan Cameron
 */
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <dirent.h>
#include <errno.h>
#include <ctype.h>
#include "iio_utils.h"

const char *iio_dir = "/sys/bus/iio/devices/";

static char * const iio_direction[] = {
	"in",
	"out",
};

/**
 * iioutils_break_up_name() - extract generic name from full channel name
 * @full_name: the full channel name
 * @generic_name: the output generic channel name
 *
 * Returns 0 on success, or a negative error code if string extraction failed.
 **/
int iioutils_break_up_name(const char *full_name, char **generic_name)
{
	char *current;
	char *w, *r;
	char *working, *prefix = "";
	int i, ret;

	for (i = 0; i < ARRAY_SIZE(iio_direction); i++)
		if (!strncmp(full_name, iio_direction[i],
			     strlen(iio_direction[i]))) {
			prefix = iio_direction[i];
			break;
		}

	current = strdup(full_name + strlen(prefix) + 1);
	if (!current)
		return -ENOMEM;

	working = strtok(current, "_\0");
	if (!working) {
		free(current);
		return -EINVAL;
	}

	w = working;
	r = working;

	while (*r != '\0') {
		if (!isdigit(*r)) {
			*w = *r;
			w++;
		}

		r++;
	}
	*w = '\0';
	ret = asprintf(generic_name, "%s_%s", prefix, working);
	free(current);

	return (ret == -1) ? -ENOMEM : 0;
}

/**
 * iioutils_get_type() - find and process _type attribute data
 * @is_signed: output whether channel is signed
 * @bytes: output how many bytes the channel storage occupies
 * @bits_used: output number of valid bits of data
 * @shift: output amount of bits to shift right data before applying bit mask
 * @mask: output a bit mask for the raw data
 * @be: output if data in big endian
 * @device_dir: the IIO device directory
 * @buffer_idx: the IIO buffer index
 * @name: the channel name
 * @generic_name: the channel type name
 *
 * Returns a value >= 0 on success, otherwise a negative error code.
 **/
static int iioutils_get_type(unsigned int *is_signed, unsigned int *bytes,
			     unsigned int *bits_used, unsigned int *shift,
			     uint64_t *mask, unsigned int *be,
			     const char *device_dir, int buffer_idx,
			     const char *name, const char *generic_name)
{
	FILE *sysfsfp;
	int ret;
	DIR *dp;
	char *scan_el_dir, *builtname, *builtname_generic, *filename = 0;
	char signchar, endianchar;
	unsigned padint;
	const struct dirent *ent;

	ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir, buffer_idx);
	if (ret < 0)
		return -ENOMEM;

	ret = asprintf(&builtname, FORMAT_TYPE_FILE, name);
	if (ret < 0) {
		ret = -ENOMEM;
		goto error_free_scan_el_dir;
	}
	ret = asprintf(&builtname_generic, FORMAT_TYPE_FILE, generic_name);
	if (ret < 0) {
		ret = -ENOMEM;
		goto error_free_builtname;
	}

	dp = opendir(scan_el_dir);
	if (!dp) {
		ret = -errno;
		goto error_free_builtname_generic;
	}

	ret = -ENOENT;
	while (ent = readdir(dp), ent)
		if ((strcmp(builtname, ent->d_name) == 0) ||
		    (strcmp(builtname_generic, ent->d_name) == 0)) {
			ret = asprintf(&filename,
				       "%s/%s", scan_el_dir, ent->d_name);
			if (ret < 0) {
				ret = -ENOMEM;
				goto error_closedir;
			}

			sysfsfp = fopen(filename, "r");
			if (!sysfsfp) {
				ret = -errno;
				fprintf(stderr, "failed to open %s\n",
					filename);
				goto error_free_filename;
			}

			ret = fscanf(sysfsfp,
				     "%ce:%c%u/%u>>%u",
				     &endianchar,
				     &signchar,
				     bits_used,
				     &padint, shift);
			if (ret < 0) {
				ret = -errno;
				fprintf(stderr,
					"failed to pass scan type description\n");
				goto error_close_sysfsfp;
			} else if (ret != 5) {
				ret = -EIO;
				fprintf(stderr,
					"scan type description didn't match\n");
				goto error_close_sysfsfp;
			}

			*be = (endianchar == 'b');
			*bytes = padint / 8;
			if (*bits_used == 64)
				*mask = ~(0ULL);
			else
				*mask = (1ULL << *bits_used) - 1ULL;

			*is_signed = (signchar == 's');
			if (fclose(sysfsfp)) {
				ret = -errno;
				fprintf(stderr, "Failed to close %s\n",
					filename);
				goto error_free_filename;
			}

			sysfsfp = 0;
			free(filename);
			filename = 0;

			/*
			 * Avoid having a more generic entry overwriting
			 * the settings.
			 */
			if (strcmp(builtname, ent->d_name) == 0)
				break;
		}

error_close_sysfsfp:
	if (sysfsfp)
		if (fclose(sysfsfp))
			perror("iioutils_get_type(): Failed to close file");

error_free_filename:
	if (filename)
		free(filename);

error_closedir