iio: core: Add function params for kernel docs

This patch adds the missing fields in kernel docs to remove
some warnings that appear when the IIO Documentation DocBook
is generated.
Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/industrialio-core.c

@@ -406,10 +406,16 @@ EXPORT_SYMBOL_GPL(iio_enum_write);
 
 /**
  * iio_format_value() - Formats a IIO value into its string representation
- * @buf: The buffer to which the formated value gets written
- * @type: One of the IIO_VAL_... constants. This decides how the val and val2
- *        parameters are formatted.
- * @vals: pointer to the values, exact meaning depends on the type parameter.
+ * @buf:	The buffer to which the formatted value gets written
+ * @type:	One of the IIO_VAL_... constants. This decides how the val
+ *		and val2 parameters are formatted.
+ * @size:	Number of IIO value entries contained in vals
+ * @vals:	Pointer to the values, exact meaning depends on the
+ *		type parameter.
+ *
+ * Return: 0 by default, a negative number on failure or the
+ *	   total number of characters written for a type that belongs
+ *	   to the IIO_VAL_... constant.
  */
 ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals)
 {
@@ -1096,6 +1102,11 @@ EXPORT_SYMBOL_GPL(devm_iio_device_free);
 
 /**
  * iio_chrdev_open() - chrdev file open for buffer access and ioctls
+ * @inode:	Inode structure for identifying the device in the file system
+ * @filp:	File structure for iio device used to keep and later access
+ *		private data
+ *
+ * Return: 0 on success or -EBUSY if the device is already opened
  **/
 static int iio_chrdev_open(struct inode *inode, struct file *filp)
 {
@@ -1114,7 +1125,11 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
 
 /**
  * iio_chrdev_release() - chrdev file close buffer access and ioctls
- **/
+ * @inode:	Inode structure pointer for the char device
+ * @filp:	File structure pointer for the char device
+ *
+ * Return: 0 for successful release
+ */
 static int iio_chrdev_release(struct inode *inode, struct file *filp)
 {
 	struct iio_dev *indio_dev = container_of(inode->i_cdev,