tools/iio/iio_utils.c - kernel/msm-4.9 - Gitiles

 /* IIO - useful set of util functionality
  *
  * Copyright (c) 2008 Jonathan Cameron
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 as published by
  * the Free Software Foundation.
  */
 #ifndef _IIO_UTILS_H
 #define _IIO_UTILS_H

 #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 < sizeof(iio_direction) / sizeof(iio_direction[0]); 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
  * @name: the channel name
  * @generic_name: the channel type name
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int iioutils_get_type(unsigned *is_signed,
 			     unsigned *bytes,
 			     unsigned *bits_used,
 			     unsigned *shift,
 			     uint64_t *mask,
 			     unsigned *be,
 			     const char *device_dir,
 			     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);
 	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 == NULL) {
 		ret = -errno;
 		goto error_free_builtname_generic;
 	}
 	ret = -ENOENT;
 	while (ent = readdir(dp), ent != NULL)
 		/*
 		 * Do we allow devices to override a generic name with
 		 * a specific one?
 		 */
 		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 == NULL) {
 				ret = -errno;
 				printf("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;
 				printf("failed to pass scan type description\n");
 				goto error_close_sysfsfp;
 			} else if (ret != 5) {
 				ret = -EIO;
 				printf("scan type description didn't match\n");
 				goto error_close_sysfsfp;
 			}
 			*be = (endianchar == 'b');
 			*bytes = padint / 8;
 			if (*bits_used == 64)
 				*mask = ~0;
 			else
 				*mask = (1 << *bits_used) - 1;
 			*is_signed = (signchar == 's');
 			if (fclose(sysfsfp)) {
 				ret = -errno;
 				printf("Failed to close %s\n", filename);
 				goto error_free_filename;
 			}

 			sysfsfp = 0;
 			free(filename);

 			filename = 0;
 		}
 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:
 	if (closedir(dp) == -1)
 		perror("iioutils_get_type(): Failed to close directory");

 error_free_builtname_generic:
 	free(builtname_generic);
 error_free_builtname:
 	free(builtname);
 error_free_scan_el_dir:
 	free(scan_el_dir);

 	return ret;
 }

 /**
  * iioutils_get_param_float() - read a float value from a channel parameter
  * @output: output the float value
  * @param_name: the parameter name to read
  * @device_dir: the IIO device directory in sysfs
  * @name: the channel name
  * @generic_name: the channel type name
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int iioutils_get_param_float(float *output,
 				    const char *param_name,
 				    const char *device_dir,
 				    const char *name,
 				    const char *generic_name)
 {
 	FILE *sysfsfp;
 	int ret;
 	DIR *dp;
 	char *builtname, *builtname_generic;
 	char *filename = NULL;
 	const struct dirent *ent;

 	ret = asprintf(&builtname, "%s_%s", name, param_name);
 	if (ret < 0)
 		return -ENOMEM;

 	ret = asprintf(&builtname_generic,
 		       "%s_%s", generic_name, param_name);
 	if (ret < 0) {
 		ret = -ENOMEM;
 		goto error_free_builtname;
 	}
 	dp = opendir(device_dir);
 	if (dp == NULL) {
 		ret = -errno;
 		goto error_free_builtname_generic;
 	}
 	ret = -ENOENT;
 	while (ent = readdir(dp), ent != NULL)
 		if ((strcmp(builtname, ent->d_name) == 0) ||
 		    (strcmp(builtname_generic, ent->d_name) == 0)) {
 			ret = asprintf(&filename,
 				       "%s/%s", device_dir, ent->d_name);
 			if (ret < 0) {
 				ret = -ENOMEM;
 				goto error_closedir;
 			}
 			sysfsfp = fopen(filename, "r");
 			if (!sysfsfp) {
 				ret = -errno;
 				goto error_free_filename;
 			}
 			errno = 0;
 			if (fscanf(sysfsfp, "%f", output) != 1)
 				ret = errno ? -errno : -ENODATA;

 			break;
 		}
 error_free_filename:
 	if (filename)
 		free(filename);
 error_closedir:
 	if (closedir(dp) == -1)
 		perror("iioutils_get_param_float(): Failed to close directory");

 error_free_builtname_generic:
 	free(builtname_generic);
 error_free_builtname:
 	free(builtname);

 	return ret;
 }

 /**
  * bsort_channel_array_by_index() - sort the array in index order
  * @ci_array: the iio_channel_info array to be sorted
  * @cnt: the amount of array elements
  **/

 void bsort_channel_array_by_index(struct iio_channel_info **ci_array,
 					 int cnt)
 {

 	struct iio_channel_info temp;
 	int x, y;

 	for (x = 0; x < cnt; x++)
 		for (y = 0; y < (cnt - 1); y++)
 			if ((*ci_array)[y].index > (*ci_array)[y+1].index) {
 				temp = (*ci_array)[y + 1];
 				(*ci_array)[y + 1] = (*ci_array)[y];
 				(*ci_array)[y] = temp;
 			}
 }

 /**
  * build_channel_array() - function to figure out what channels are present
  * @device_dir: the IIO device directory in sysfs
  * @ci_array: output the resulting array of iio_channel_info
  * @counter: output the amount of array elements
  *
  * Returns 0 on success, otherwise a negative error code.
  **/
 int build_channel_array(const char *device_dir,
 			      struct iio_channel_info **ci_array,
 			      int *counter)
 {
 	DIR *dp;
 	FILE *sysfsfp;
 	int count = 0, i;
 	struct iio_channel_info *current;
 	int ret;
 	const struct dirent *ent;
 	char *scan_el_dir;
 	char *filename;

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

 	dp = opendir(scan_el_dir);
 	if (dp == NULL) {
 		ret = -errno;
 		goto error_free_name;
 	}
 	while (ent = readdir(dp), ent != NULL)
 		if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
 			   "_en") == 0) {
 			ret = asprintf(&filename,
 				       "%s/%s", scan_el_dir, ent->d_name);
 			if (ret < 0) {
 				ret = -ENOMEM;
 				goto error_close_dir;
 			}
 			sysfsfp = fopen(filename, "r");
 			if (sysfsfp == NULL) {
 				ret = -errno;
 				free(filename);
 				goto error_close_dir;
 			}
 			errno = 0;
 			if (fscanf(sysfsfp, "%i", &ret) != 1) {
 				ret = errno ? -errno : -ENODATA;
 				if (fclose(sysfsfp))
 					perror("build_channel_array(): Failed to close file");

 				free(filename);
 				goto error_close_dir;
 			}

 			if (ret == 1)
 				(*counter)++;
 			if (fclose(sysfsfp)) {
 				ret = -errno;
 				free(filename);
 				goto error_close_dir;
 			}

 			free(filename);
 		}
 	*ci_array = malloc(sizeof(**ci_array) * (*counter));
 	if (*ci_array == NULL) {
 		ret = -ENOMEM;
 		goto error_close_dir;
 	}
 	seekdir(dp, 0);
 	while (ent = readdir(dp), ent != NULL) {
 		if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
 			   "_en") == 0) {
 			int current_enabled = 0;

 			current = &(*ci_array)[count++];
 			ret = asprintf(&filename,
 				       "%s/%s", scan_el_dir, ent->d_name);
 			if (ret < 0) {
 				ret = -ENOMEM;
 				/* decrement count to avoid freeing name */
 				count--;
 				goto error_cleanup_array;
 			}
 			sysfsfp = fopen(filename, "r");
 			if (sysfsfp == NULL) {
 				ret = -errno;
 				free(filename);
 				count--;
 				goto error_cleanup_array;
 			}
 			errno = 0;
 			if (fscanf(sysfsfp, "%i", &current_enabled) != 1) {
 				ret = errno ? -errno : -ENODATA;
 				free(filename);
 				count--;
 				goto error_cleanup_array;
 			}

 			if (fclose(sysfsfp)) {
 				ret = -errno;
 				free(filename);
 				count--;
 				goto error_cleanup_array;
 			}

 			if (!current_enabled) {
 				free(filename);
 				count--;
 				continue;
 			}

 			current->scale = 1.0;
 			current->offset = 0;
 			current->name = strndup(ent->d_name,
 						strlen(ent->d_name) -
 						strlen("_en"));
 			if (current->name == NULL) {
 				free(filename);
 				ret = -ENOMEM;
 				count--;
 				goto error_cleanup_array;
 			}
 			/* Get the generic and specific name elements */
 			ret = iioutils_break_up_name(current->name,
 						     &current->generic_name);
 			if (ret) {
 				free(filename);
 				free(current->name);
 				count--;
 				goto error_cleanup_array;
 			}
 			ret = asprintf(&filename,
 				       "%s/%s_index",
 				       scan_el_dir,
 				       current->name);
 			if (ret < 0) {
 				free(filename);
 				ret = -ENOMEM;
 				goto error_cleanup_array;
 			}
 			sysfsfp = fopen(filename, "r");
 			if (sysfsfp == NULL) {
 				ret = -errno;
 				printf("failed to open %s\n", filename);
 				free(filename);
 				goto error_cleanup_array;
 			}

 			errno = 0;
 			if (fscanf(sysfsfp, "%u", &current->index) != 1) {
 				ret = errno ? -errno : -ENODATA;
 				if (fclose(sysfsfp))
 					perror("build_channel_array(): Failed to close file");

 				free(filename);
 				goto error_cleanup_array;
 			}

 			if (fclose(sysfsfp)) {
 				ret = -errno;
 				free(filename);
 				goto error_cleanup_array;
 			}

 			free(filename);
 			/* Find the scale */
 			ret = iioutils_get_param_float(&current->scale,
 						       "scale",
 						       device_dir,
 						       current->name,
 						       current->generic_name);
 			if (ret < 0)
 				goto error_cleanup_array;
 			ret = iioutils_get_param_float(&current->offset,
 						       "offset",
 						       device_dir,
 						       current->name,
 						       current->generic_name);
 			if (ret < 0)
 				goto error_cleanup_array;
 			ret = iioutils_get_type(&current->is_signed,
 						&current->bytes,
 						&current->bits_used,
 						&current->shift,
 						&current->mask,
 						&current->be,
 						device_dir,
 						current->name,
 						current->generic_name);
 			if (ret < 0)
 				goto error_cleanup_array;
 		}
 	}

 	if (closedir(dp) == -1) {
 		ret = -errno;
 		goto error_cleanup_array;
 	}

 	free(scan_el_dir);
 	/* reorder so that the array is in index order */
 	bsort_channel_array_by_index(ci_array, *counter);

 	return 0;

 error_cleanup_array:
 	for (i = count - 1;  i >= 0; i--) {
 		free((*ci_array)[i].name);
 		free((*ci_array)[i].generic_name);
 	}
 	free(*ci_array);
 error_close_dir:
 	if (dp)
 		if (closedir(dp) == -1)
 			perror("build_channel_array(): Failed to close dir");

 error_free_name:
 	free(scan_el_dir);

 	return ret;
 }

 int calc_digits(int num)
 {
 	int count = 0;

 	while (num != 0) {
 		num /= 10;
 		count++;
 	}

 	return count;
 }

 /**
  * find_type_by_name() - function to match top level types by name
  * @name: top level type instance name
  * @type: the type of top level instance being searched
  *
  * Returns the device number of a matched IIO device on success, otherwise a
  * negative error code.
  * Typical types this is used for are device and trigger.
  **/
 int find_type_by_name(const char *name, const char *type)
 {
 	const struct dirent *ent;
 	int number, numstrlen, ret;

 	FILE *nameFile;
 	DIR *dp;
 	char thisname[IIO_MAX_NAME_LENGTH];
 	char *filename;

 	dp = opendir(iio_dir);
 	if (dp == NULL) {
 		printf("No industrialio devices available\n");
 		return -ENODEV;
 	}

 	while (ent = readdir(dp), ent != NULL) {
 		if (strcmp(ent->d_name, ".") != 0 &&
 			strcmp(ent->d_name, "..") != 0 &&
 			strlen(ent->d_name) > strlen(type) &&
 			strncmp(ent->d_name, type, strlen(type)) == 0) {
 			errno = 0;
 			ret = sscanf(ent->d_name + strlen(type), "%d", &number);
 			if (ret < 0) {
 				ret = -errno;
 				printf("failed to read element number\n");
 				goto error_close_dir;
 			} else if (ret != 1) {
 				ret = -EIO;
 				printf("failed to match element number\n");
 				goto error_close_dir;
 			}

 			numstrlen = calc_digits(number);
 			/* verify the next character is not a colon */
 			if (strncmp(ent->d_name + strlen(type) + numstrlen,
 					":",
 					1) != 0) {
 				filename = malloc(strlen(iio_dir)
 						+ strlen(type)
 						+ numstrlen
 						+ 6);
 				if (filename == NULL) {
 					ret = -ENOMEM;
 					goto error_close_dir;
 				}

 				ret = sprintf(filename, "%s%s%d/name", iio_dir,
 					      type, number);
 				if (ret < 0) {
 					free(filename);
 					goto error_close_dir;
 				}

 				nameFile = fopen(filename, "r");
 				if (!nameFile) {
 					free(filename);
 					continue;
 				}
 				free(filename);
 				errno = 0;
 				if (fscanf(nameFile, "%s", thisname) != 1) {
 					ret = errno ? -errno : -ENODATA;
 					goto error_close_dir;
 				}

 				if (fclose(nameFile)) {
 					ret = -errno;
 					goto error_close_dir;
 				}

 				if (strcmp(name, thisname) == 0) {
 					if (closedir(dp) == -1)
 						return -errno;
 					return number;
 				}
 			}
 		}
 	}
 	if (closedir(dp) == -1)
 		return -errno;

 	return -ENODEV;

 error_close_dir:
 	if (closedir(dp) == -1)
 		perror("find_type_by_name(): Failed to close directory");
 	return ret;
 }

 static int _write_sysfs_int(char *filename, char *basedir, int val, int verify)
 {
 	int ret = 0;
 	FILE *sysfsfp;
 	int test;
 	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

 	if (temp == NULL)
 		return -ENOMEM;
 	ret = sprintf(temp, "%s/%s", basedir, filename);
 	if (ret < 0)
 		goto error_free;

 	sysfsfp = fopen(temp, "w");
 	if (sysfsfp == NULL) {
 		ret = -errno;
 		printf("failed to open %s\n", temp);
 		goto error_free;
 	}
 	ret = fprintf(sysfsfp, "%d", val);
 	if (ret < 0) {
 		if (fclose(sysfsfp))
 			perror("_write_sysfs_int(): Failed to close dir");

 		goto error_free;
 	}

 	if (fclose(sysfsfp)) {
 		ret = -errno;
 		goto error_free;
 	}

 	if (verify) {
 		sysfsfp = fopen(temp, "r");
 		if (sysfsfp == NULL) {
 			ret = -errno;
 			printf("failed to open %s\n", temp);
 			goto error_free;
 		}
 		if (fscanf(sysfsfp, "%d", &test) != 1) {
 			ret = errno ? -errno : -ENODATA;
 			if (fclose(sysfsfp))
 				perror("_write_sysfs_int(): Failed to close dir");

 			goto error_free;
 		}

 		if (fclose(sysfsfp)) {
 			ret = -errno;
 			goto error_free;
 		}

 		if (test != val) {
 			printf("Possible failure in int write %d to %s%s\n",
 				val,
 				basedir,
 				filename);
 			ret = -1;
 		}
 	}
 error_free:
 	free(temp);
 	return ret;
 }

 /**
  * write_sysfs_int() - write an integer value to a sysfs file
  * @filename: name of the file to write to
  * @basedir: the sysfs directory in which the file is to be found
  * @val: integer value to write to file
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int write_sysfs_int(char *filename, char *basedir, int val)
 {
 	return _write_sysfs_int(filename, basedir, val, 0);
 }

 /**
  * write_sysfs_int_and_verify() - write an integer value to a sysfs file
  *				  and verify
  * @filename: name of the file to write to
  * @basedir: the sysfs directory in which the file is to be found
  * @val: integer value to write to file
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int write_sysfs_int_and_verify(char *filename, char *basedir, int val)
 {
 	return _write_sysfs_int(filename, basedir, val, 1);
 }

 static int _write_sysfs_string(char *filename, char *basedir, char *val,
 			       int verify)
 {
 	int ret = 0;
 	FILE  *sysfsfp;
 	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

 	if (temp == NULL) {
 		printf("Memory allocation failed\n");
 		return -ENOMEM;
 	}
 	ret = sprintf(temp, "%s/%s", basedir, filename);
 	if (ret < 0)
 		goto error_free;

 	sysfsfp = fopen(temp, "w");
 	if (sysfsfp == NULL) {
 		ret = -errno;
 		printf("Could not open %s\n", temp);
 		goto error_free;
 	}
 	ret = fprintf(sysfsfp, "%s", val);
 	if (ret < 0) {
 		if (fclose(sysfsfp))
 			perror("_write_sysfs_string(): Failed to close dir");

 		goto error_free;
 	}

 	if (fclose(sysfsfp)) {
 		ret = -errno;
 		goto error_free;
 	}

 	if (verify) {
 		sysfsfp = fopen(temp, "r");
 		if (sysfsfp == NULL) {
 			ret = -errno;
 			printf("could not open file to verify\n");
 			goto error_free;
 		}
 		if (fscanf(sysfsfp, "%s", temp) != 1) {
 			ret = errno ? -errno : -ENODATA;
 			if (fclose(sysfsfp))
 				perror("_write_sysfs_string(): Failed to close dir");

 			goto error_free;
 		}

 		if (fclose(sysfsfp)) {
 			ret = -errno;
 			goto error_free;
 		}

 		if (strcmp(temp, val) != 0) {
 			printf("Possible failure in string write of %s "
 				"Should be %s "
 				"written to %s\%s\n",
 				temp,
 				val,
 				basedir,
 				filename);
 			ret = -1;
 		}
 	}
 error_free:
 	free(temp);

 	return ret;
 }

 /**
  * write_sysfs_string_and_verify() - string write, readback and verify
  * @filename: name of file to write to
  * @basedir: the sysfs directory in which the file is to be found
  * @val: the string to write
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int write_sysfs_string_and_verify(char *filename, char *basedir, char *val)
 {
 	return _write_sysfs_string(filename, basedir, val, 1);
 }

 /**
  * write_sysfs_string() - write string to a sysfs file
  * @filename: name of file to write to
  * @basedir: the sysfs directory in which the file is to be found
  * @val: the string to write
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int write_sysfs_string(char *filename, char *basedir, char *val)
 {
 	return _write_sysfs_string(filename, basedir, val, 0);
 }

 /**
  * read_sysfs_posint() - read an integer value from file
  * @filename: name of file to read from
  * @basedir: the sysfs directory in which the file is to be found
  *
  * Returns the read integer value >= 0 on success, otherwise a negative error
  * code.
  **/
 int read_sysfs_posint(char *filename, char *basedir)
 {
 	int ret;
 	FILE  *sysfsfp;
 	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

 	if (temp == NULL) {
 		printf("Memory allocation failed");
 		return -ENOMEM;
 	}
 	ret = sprintf(temp, "%s/%s", basedir, filename);
 	if (ret < 0)
 		goto error_free;

 	sysfsfp = fopen(temp, "r");
 	if (sysfsfp == NULL) {
 		ret = -errno;
 		goto error_free;
 	}
 	errno = 0;
 	if (fscanf(sysfsfp, "%d\n", &ret) != 1) {
 		ret = errno ? -errno : -ENODATA;
 		if (fclose(sysfsfp))
 			perror("read_sysfs_posint(): Failed to close dir");

 		goto error_free;
 	}

 	if (fclose(sysfsfp))
 		ret = -errno;

 error_free:
 	free(temp);
 	return ret;
 }

 /**
  * read_sysfs_float() - read a float value from file
  * @filename: name of file to read from
  * @basedir: the sysfs directory in which the file is to be found
  * @val: output the read float value
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int read_sysfs_float(char *filename, char *basedir, float *val)
 {
 	int ret = 0;
 	FILE  *sysfsfp;
 	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

 	if (temp == NULL) {
 		printf("Memory allocation failed");
 		return -ENOMEM;
 	}
 	ret = sprintf(temp, "%s/%s", basedir, filename);
 	if (ret < 0)
 		goto error_free;

 	sysfsfp = fopen(temp, "r");
 	if (sysfsfp == NULL) {
 		ret = -errno;
 		goto error_free;
 	}
 	errno = 0;
 	if (fscanf(sysfsfp, "%f\n", val) != 1) {
 		ret = errno ? -errno : -ENODATA;
 		if (fclose(sysfsfp))
 			perror("read_sysfs_float(): Failed to close dir");

 		goto error_free;
 	}

 	if (fclose(sysfsfp))
 		ret = -errno;

 error_free:
 	free(temp);
 	return ret;
 }

 /**
  * read_sysfs_string() - read a string from file
  * @filename: name of file to read from
  * @basedir: the sysfs directory in which the file is to be found
  * @str: output the read string
  *
  * Returns a value >= 0 on success, otherwise a negative error code.
  **/
 int read_sysfs_string(const char *filename, const char *basedir, char *str)
 {
 	int ret = 0;
 	FILE  *sysfsfp;
 	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

 	if (temp == NULL) {
 		printf("Memory allocation failed");
 		return -ENOMEM;
 	}
 	ret = sprintf(temp, "%s/%s", basedir, filename);
 	if (ret < 0)
 		goto error_free;

 	sysfsfp = fopen(temp, "r");
 	if (sysfsfp == NULL) {
 		ret = -errno;
 		goto error_free;
 	}
 	errno = 0;
 	if (fscanf(sysfsfp, "%s\n", str) != 1) {
 		ret = errno ? -errno : -ENODATA;
 		if (fclose(sysfsfp))
 			perror("read_sysfs_string(): Failed to close dir");

 		goto error_free;
 	}

 	if (fclose(sysfsfp))
 		ret = -errno;

 error_free:
 	free(temp);
 	return ret;
 }

 #endif /* _IIO_UTILS_H */
	/* IIO - useful set of util functionality
	*
	* Copyright (c) 2008 Jonathan Cameron
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 as published by
	* the Free Software Foundation.
	*/
	#ifndef _IIO_UTILS_H
	#define _IIO_UTILS_H

	#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 < sizeof(iio_direction) / sizeof(iio_direction[0]); 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
	* @name: the channel name
	* @generic_name: the channel type name
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int iioutils_get_type(unsigned *is_signed,
	unsigned *bytes,
	unsigned *bits_used,
	unsigned *shift,
	uint64_t *mask,
	unsigned *be,
	const char *device_dir,
	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);
	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 == NULL) {
	ret = -errno;
	goto error_free_builtname_generic;
	}
	ret = -ENOENT;
	while (ent = readdir(dp), ent != NULL)
	/*
	* Do we allow devices to override a generic name with
	* a specific one?
	*/
	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 == NULL) {
	ret = -errno;
	printf("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;
	printf("failed to pass scan type description\n");
	goto error_close_sysfsfp;
	} else if (ret != 5) {
	ret = -EIO;
	printf("scan type description didn't match\n");
	goto error_close_sysfsfp;
	}
	*be = (endianchar == 'b');
	*bytes = padint / 8;
	if (*bits_used == 64)
	*mask = ~0;
	else
	mask = (1 << bits_used) - 1;
	*is_signed = (signchar == 's');
	if (fclose(sysfsfp)) {
	ret = -errno;
	printf("Failed to close %s\n", filename);
	goto error_free_filename;
	}

	sysfsfp = 0;
	free(filename);

	filename = 0;
	}
	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:
	if (closedir(dp) == -1)
	perror("iioutils_get_type(): Failed to close directory");

	error_free_builtname_generic:
	free(builtname_generic);
	error_free_builtname:
	free(builtname);
	error_free_scan_el_dir:
	free(scan_el_dir);

	return ret;
	}

	/**
	* iioutils_get_param_float() - read a float value from a channel parameter
	* @output: output the float value
	* @param_name: the parameter name to read
	* @device_dir: the IIO device directory in sysfs
	* @name: the channel name
	* @generic_name: the channel type name
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int iioutils_get_param_float(float *output,
	const char *param_name,
	const char *device_dir,
	const char *name,
	const char *generic_name)
	{
	FILE *sysfsfp;
	int ret;
	DIR *dp;
	char builtname, builtname_generic;
	char *filename = NULL;
	const struct dirent *ent;

	ret = asprintf(&builtname, "%s_%s", name, param_name);
	if (ret < 0)
	return -ENOMEM;

	ret = asprintf(&builtname_generic,
	"%s_%s", generic_name, param_name);
	if (ret < 0) {
	ret = -ENOMEM;
	goto error_free_builtname;
	}
	dp = opendir(device_dir);
	if (dp == NULL) {
	ret = -errno;
	goto error_free_builtname_generic;
	}
	ret = -ENOENT;
	while (ent = readdir(dp), ent != NULL)
	if ((strcmp(builtname, ent->d_name) == 0) \|\|
	(strcmp(builtname_generic, ent->d_name) == 0)) {
	ret = asprintf(&filename,
	"%s/%s", device_dir, ent->d_name);
	if (ret < 0) {
	ret = -ENOMEM;
	goto error_closedir;
	}
	sysfsfp = fopen(filename, "r");
	if (!sysfsfp) {
	ret = -errno;
	goto error_free_filename;
	}
	errno = 0;
	if (fscanf(sysfsfp, "%f", output) != 1)
	ret = errno ? -errno : -ENODATA;

	break;
	}
	error_free_filename:
	if (filename)
	free(filename);
	error_closedir:
	if (closedir(dp) == -1)
	perror("iioutils_get_param_float(): Failed to close directory");

	error_free_builtname_generic:
	free(builtname_generic);
	error_free_builtname:
	free(builtname);

	return ret;
	}

	/**
	* bsort_channel_array_by_index() - sort the array in index order
	* @ci_array: the iio_channel_info array to be sorted
	* @cnt: the amount of array elements
	**/

	void bsort_channel_array_by_index(struct iio_channel_info **ci_array,
	int cnt)
	{

	struct iio_channel_info temp;
	int x, y;

	for (x = 0; x < cnt; x++)
	for (y = 0; y < (cnt - 1); y++)
	if ((ci_array)[y].index > (ci_array)[y+1].index) {
	temp = (*ci_array)[y + 1];
	(ci_array)[y + 1] = (ci_array)[y];
	(*ci_array)[y] = temp;
	}
	}

	/**
	* build_channel_array() - function to figure out what channels are present
	* @device_dir: the IIO device directory in sysfs
	* @ci_array: output the resulting array of iio_channel_info
	* @counter: output the amount of array elements
	*
	* Returns 0 on success, otherwise a negative error code.
	**/
	int build_channel_array(const char *device_dir,
	struct iio_channel_info **ci_array,
	int *counter)
	{
	DIR *dp;
	FILE *sysfsfp;
	int count = 0, i;
	struct iio_channel_info *current;
	int ret;
	const struct dirent *ent;
	char *scan_el_dir;
	char *filename;

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

	dp = opendir(scan_el_dir);
	if (dp == NULL) {
	ret = -errno;
	goto error_free_name;
	}
	while (ent = readdir(dp), ent != NULL)
	if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
	"_en") == 0) {
	ret = asprintf(&filename,
	"%s/%s", scan_el_dir, ent->d_name);
	if (ret < 0) {
	ret = -ENOMEM;
	goto error_close_dir;
	}
	sysfsfp = fopen(filename, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	free(filename);
	goto error_close_dir;
	}
	errno = 0;
	if (fscanf(sysfsfp, "%i", &ret) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("build_channel_array(): Failed to close file");

	free(filename);
	goto error_close_dir;
	}

	if (ret == 1)
	(*counter)++;
	if (fclose(sysfsfp)) {
	ret = -errno;
	free(filename);
	goto error_close_dir;
	}

	free(filename);
	}
	ci_array = malloc(sizeof(ci_array) (*counter));
	if (*ci_array == NULL) {
	ret = -ENOMEM;
	goto error_close_dir;
	}
	seekdir(dp, 0);
	while (ent = readdir(dp), ent != NULL) {
	if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
	"_en") == 0) {
	int current_enabled = 0;

	current = &(*ci_array)[count++];
	ret = asprintf(&filename,
	"%s/%s", scan_el_dir, ent->d_name);
	if (ret < 0) {
	ret = -ENOMEM;
	/* decrement count to avoid freeing name */
	count--;
	goto error_cleanup_array;
	}
	sysfsfp = fopen(filename, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	free(filename);
	count--;
	goto error_cleanup_array;
	}
	errno = 0;
	if (fscanf(sysfsfp, "%i", &current_enabled) != 1) {
	ret = errno ? -errno : -ENODATA;
	free(filename);
	count--;
	goto error_cleanup_array;
	}

	if (fclose(sysfsfp)) {
	ret = -errno;
	free(filename);
	count--;
	goto error_cleanup_array;
	}

	if (!current_enabled) {
	free(filename);
	count--;
	continue;
	}

	current->scale = 1.0;
	current->offset = 0;
	current->name = strndup(ent->d_name,
	strlen(ent->d_name) -
	strlen("_en"));
	if (current->name == NULL) {
	free(filename);
	ret = -ENOMEM;
	count--;
	goto error_cleanup_array;
	}
	/* Get the generic and specific name elements */
	ret = iioutils_break_up_name(current->name,
	&current->generic_name);
	if (ret) {
	free(filename);
	free(current->name);
	count--;
	goto error_cleanup_array;
	}
	ret = asprintf(&filename,
	"%s/%s_index",
	scan_el_dir,
	current->name);
	if (ret < 0) {
	free(filename);
	ret = -ENOMEM;
	goto error_cleanup_array;
	}
	sysfsfp = fopen(filename, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	printf("failed to open %s\n", filename);
	free(filename);
	goto error_cleanup_array;
	}

	errno = 0;
	if (fscanf(sysfsfp, "%u", &current->index) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("build_channel_array(): Failed to close file");

	free(filename);
	goto error_cleanup_array;
	}

	if (fclose(sysfsfp)) {
	ret = -errno;
	free(filename);
	goto error_cleanup_array;
	}

	free(filename);
	/* Find the scale */
	ret = iioutils_get_param_float(&current->scale,
	"scale",
	device_dir,
	current->name,
	current->generic_name);
	if (ret < 0)
	goto error_cleanup_array;
	ret = iioutils_get_param_float(&current->offset,
	"offset",
	device_dir,
	current->name,
	current->generic_name);
	if (ret < 0)
	goto error_cleanup_array;
	ret = iioutils_get_type(&current->is_signed,
	&current->bytes,
	&current->bits_used,
	&current->shift,
	&current->mask,
	&current->be,
	device_dir,
	current->name,
	current->generic_name);
	if (ret < 0)
	goto error_cleanup_array;
	}
	}

	if (closedir(dp) == -1) {
	ret = -errno;
	goto error_cleanup_array;
	}

	free(scan_el_dir);
	/* reorder so that the array is in index order */
	bsort_channel_array_by_index(ci_array, *counter);

	return 0;

	error_cleanup_array:
	for (i = count - 1; i >= 0; i--) {
	free((*ci_array)[i].name);
	free((*ci_array)[i].generic_name);
	}
	free(*ci_array);
	error_close_dir:
	if (dp)
	if (closedir(dp) == -1)
	perror("build_channel_array(): Failed to close dir");

	error_free_name:
	free(scan_el_dir);

	return ret;
	}

	int calc_digits(int num)
	{
	int count = 0;

	while (num != 0) {
	num /= 10;
	count++;
	}

	return count;
	}

	/**
	* find_type_by_name() - function to match top level types by name
	* @name: top level type instance name
	* @type: the type of top level instance being searched
	*
	* Returns the device number of a matched IIO device on success, otherwise a
	* negative error code.
	* Typical types this is used for are device and trigger.
	**/
	int find_type_by_name(const char name, const char type)
	{
	const struct dirent *ent;
	int number, numstrlen, ret;

	FILE *nameFile;
	DIR *dp;
	char thisname[IIO_MAX_NAME_LENGTH];
	char *filename;

	dp = opendir(iio_dir);
	if (dp == NULL) {
	printf("No industrialio devices available\n");
	return -ENODEV;
	}

	while (ent = readdir(dp), ent != NULL) {
	if (strcmp(ent->d_name, ".") != 0 &&
	strcmp(ent->d_name, "..") != 0 &&
	strlen(ent->d_name) > strlen(type) &&
	strncmp(ent->d_name, type, strlen(type)) == 0) {
	errno = 0;
	ret = sscanf(ent->d_name + strlen(type), "%d", &number);
	if (ret < 0) {
	ret = -errno;
	printf("failed to read element number\n");
	goto error_close_dir;
	} else if (ret != 1) {
	ret = -EIO;
	printf("failed to match element number\n");
	goto error_close_dir;
	}

	numstrlen = calc_digits(number);
	/* verify the next character is not a colon */
	if (strncmp(ent->d_name + strlen(type) + numstrlen,
	":",
	1) != 0) {
	filename = malloc(strlen(iio_dir)
	+ strlen(type)
	+ numstrlen
	+ 6);
	if (filename == NULL) {
	ret = -ENOMEM;
	goto error_close_dir;
	}

	ret = sprintf(filename, "%s%s%d/name", iio_dir,
	type, number);
	if (ret < 0) {
	free(filename);
	goto error_close_dir;
	}

	nameFile = fopen(filename, "r");
	if (!nameFile) {
	free(filename);
	continue;
	}
	free(filename);
	errno = 0;
	if (fscanf(nameFile, "%s", thisname) != 1) {
	ret = errno ? -errno : -ENODATA;
	goto error_close_dir;
	}

	if (fclose(nameFile)) {
	ret = -errno;
	goto error_close_dir;
	}

	if (strcmp(name, thisname) == 0) {
	if (closedir(dp) == -1)
	return -errno;
	return number;
	}
	}
	}
	}
	if (closedir(dp) == -1)
	return -errno;

	return -ENODEV;

	error_close_dir:
	if (closedir(dp) == -1)
	perror("find_type_by_name(): Failed to close directory");
	return ret;
	}

	static int _write_sysfs_int(char filename, char basedir, int val, int verify)
	{
	int ret = 0;
	FILE *sysfsfp;
	int test;
	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

	if (temp == NULL)
	return -ENOMEM;
	ret = sprintf(temp, "%s/%s", basedir, filename);
	if (ret < 0)
	goto error_free;

	sysfsfp = fopen(temp, "w");
	if (sysfsfp == NULL) {
	ret = -errno;
	printf("failed to open %s\n", temp);
	goto error_free;
	}
	ret = fprintf(sysfsfp, "%d", val);
	if (ret < 0) {
	if (fclose(sysfsfp))
	perror("_write_sysfs_int(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp)) {
	ret = -errno;
	goto error_free;
	}

	if (verify) {
	sysfsfp = fopen(temp, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	printf("failed to open %s\n", temp);
	goto error_free;
	}
	if (fscanf(sysfsfp, "%d", &test) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("_write_sysfs_int(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp)) {
	ret = -errno;
	goto error_free;
	}

	if (test != val) {
	printf("Possible failure in int write %d to %s%s\n",
	val,
	basedir,
	filename);
	ret = -1;
	}
	}
	error_free:
	free(temp);
	return ret;
	}

	/**
	* write_sysfs_int() - write an integer value to a sysfs file
	* @filename: name of the file to write to
	* @basedir: the sysfs directory in which the file is to be found
	* @val: integer value to write to file
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int write_sysfs_int(char filename, char basedir, int val)
	{
	return _write_sysfs_int(filename, basedir, val, 0);
	}

	/**
	* write_sysfs_int_and_verify() - write an integer value to a sysfs file
	* and verify
	* @filename: name of the file to write to
	* @basedir: the sysfs directory in which the file is to be found
	* @val: integer value to write to file
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int write_sysfs_int_and_verify(char filename, char basedir, int val)
	{
	return _write_sysfs_int(filename, basedir, val, 1);
	}

	static int _write_sysfs_string(char filename, char basedir, char *val,
	int verify)
	{
	int ret = 0;
	FILE *sysfsfp;
	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

	if (temp == NULL) {
	printf("Memory allocation failed\n");
	return -ENOMEM;
	}
	ret = sprintf(temp, "%s/%s", basedir, filename);
	if (ret < 0)
	goto error_free;

	sysfsfp = fopen(temp, "w");
	if (sysfsfp == NULL) {
	ret = -errno;
	printf("Could not open %s\n", temp);
	goto error_free;
	}
	ret = fprintf(sysfsfp, "%s", val);
	if (ret < 0) {
	if (fclose(sysfsfp))
	perror("_write_sysfs_string(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp)) {
	ret = -errno;
	goto error_free;
	}

	if (verify) {
	sysfsfp = fopen(temp, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	printf("could not open file to verify\n");
	goto error_free;
	}
	if (fscanf(sysfsfp, "%s", temp) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("_write_sysfs_string(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp)) {
	ret = -errno;
	goto error_free;
	}

	if (strcmp(temp, val) != 0) {
	printf("Possible failure in string write of %s "
	"Should be %s "
	"written to %s\%s\n",
	temp,
	val,
	basedir,
	filename);
	ret = -1;
	}
	}
	error_free:
	free(temp);

	return ret;
	}

	/**
	* write_sysfs_string_and_verify() - string write, readback and verify
	* @filename: name of file to write to
	* @basedir: the sysfs directory in which the file is to be found
	* @val: the string to write
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int write_sysfs_string_and_verify(char filename, char basedir, char *val)
	{
	return _write_sysfs_string(filename, basedir, val, 1);
	}

	/**
	* write_sysfs_string() - write string to a sysfs file
	* @filename: name of file to write to
	* @basedir: the sysfs directory in which the file is to be found
	* @val: the string to write
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int write_sysfs_string(char filename, char basedir, char *val)
	{
	return _write_sysfs_string(filename, basedir, val, 0);
	}

	/**
	* read_sysfs_posint() - read an integer value from file
	* @filename: name of file to read from
	* @basedir: the sysfs directory in which the file is to be found
	*
	* Returns the read integer value >= 0 on success, otherwise a negative error
	* code.
	**/
	int read_sysfs_posint(char filename, char basedir)
	{
	int ret;
	FILE *sysfsfp;
	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

	if (temp == NULL) {
	printf("Memory allocation failed");
	return -ENOMEM;
	}
	ret = sprintf(temp, "%s/%s", basedir, filename);
	if (ret < 0)
	goto error_free;

	sysfsfp = fopen(temp, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	goto error_free;
	}
	errno = 0;
	if (fscanf(sysfsfp, "%d\n", &ret) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("read_sysfs_posint(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp))
	ret = -errno;

	error_free:
	free(temp);
	return ret;
	}

	/**
	* read_sysfs_float() - read a float value from file
	* @filename: name of file to read from
	* @basedir: the sysfs directory in which the file is to be found
	* @val: output the read float value
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int read_sysfs_float(char filename, char basedir, float *val)
	{
	int ret = 0;
	FILE *sysfsfp;
	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

	if (temp == NULL) {
	printf("Memory allocation failed");
	return -ENOMEM;
	}
	ret = sprintf(temp, "%s/%s", basedir, filename);
	if (ret < 0)
	goto error_free;

	sysfsfp = fopen(temp, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	goto error_free;
	}
	errno = 0;
	if (fscanf(sysfsfp, "%f\n", val) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("read_sysfs_float(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp))
	ret = -errno;

	error_free:
	free(temp);
	return ret;
	}

	/**
	* read_sysfs_string() - read a string from file
	* @filename: name of file to read from
	* @basedir: the sysfs directory in which the file is to be found
	* @str: output the read string
	*
	* Returns a value >= 0 on success, otherwise a negative error code.
	**/
	int read_sysfs_string(const char filename, const char basedir, char *str)
	{
	int ret = 0;
	FILE *sysfsfp;
	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);

	if (temp == NULL) {
	printf("Memory allocation failed");
	return -ENOMEM;
	}
	ret = sprintf(temp, "%s/%s", basedir, filename);
	if (ret < 0)
	goto error_free;

	sysfsfp = fopen(temp, "r");
	if (sysfsfp == NULL) {
	ret = -errno;
	goto error_free;
	}
	errno = 0;
	if (fscanf(sysfsfp, "%s\n", str) != 1) {
	ret = errno ? -errno : -ENODATA;
	if (fclose(sysfsfp))
	perror("read_sysfs_string(): Failed to close dir");

	goto error_free;
	}

	if (fclose(sysfsfp))
	ret = -errno;

	error_free:
	free(temp);
	return ret;
	}

	#endif /* _IIO_UTILS_H */