Commit d9a0e73c authored by Lars-Peter Clausen's avatar Lars-Peter Clausen Committed by Jonathan Cameron
Browse files

iio: Handle enumerated properties with gaps 



Some enums might have gaps or reserved values in the middle of their value
range. E.g. consider a 2-bit enum where the values 0, 1 and 3 have a
meaning, but 2 is a reserved value and can not be used.

Add support for such enums to the IIO enum helper functions. A reserved
values is marked by setting its entry in the items array to NULL rather
than the normal descriptive string value.

Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210107112049.10815-1-alexandru.ardelean@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 3cc718bc

drivers/iio/industrialio-core.c

+36 −3
Original line number Diff line number Diff line
@@ -169,6 +169,36 @@ static const char * const iio_chan_info_postfix[] = { 
	[IIO_CHAN_INFO_CALIBAMBIENT] = "calibambient",

};



/**

 * iio_sysfs_match_string_with_gaps - matches given string in an array with gaps

 * @array: array of strings

 * @n: number of strings in the array

 * @str: string to match with

 *

 * Returns index of @str in the @array or -EINVAL, similar to match_string().

 * Uses sysfs_streq instead of strcmp for matching.

 *

 * This routine will look for a string in an array of strings.

 * The search will continue until the element is found or the n-th element

 * is reached, regardless of any NULL elements in the array.

 */

static int iio_sysfs_match_string_with_gaps(const char * const *array, size_t n,

					    const char *str)

{

	const char *item;

	int index;



	for (index = 0; index < n; index++) {

		item = array[index];

		if (!item)

			continue;

		if (sysfs_streq(item, str))

			return index;

	}



	return -EINVAL;

}



#if defined(CONFIG_DEBUG_FS)

/*

 * There's also a CONFIG_DEBUG_FS guard in include/linux/iio/iio.h for
@@ -470,8 +500,11 @@ ssize_t iio_enum_available_read(struct iio_dev *indio_dev, 
	if (!e->num_items)

		return 0;



	for (i = 0; i < e->num_items; ++i)

	for (i = 0; i < e->num_items; ++i) {

		if (!e->items[i])

			continue;

		len += scnprintf(buf + len, PAGE_SIZE - len, "%s ", e->items[i]);

	}



	/* replace last space with a newline */

	buf[len - 1] = '\n';
@@ -492,7 +525,7 @@ ssize_t iio_enum_read(struct iio_dev *indio_dev, 
	i = e->get(indio_dev, chan);

	if (i < 0)

		return i;

	else if (i >= e->num_items)

	else if (i >= e->num_items || !e->items[i])

		return -EINVAL;



	return snprintf(buf, PAGE_SIZE, "%s\n", e->items[i]);
@@ -509,7 +542,7 @@ ssize_t iio_enum_write(struct iio_dev *indio_dev, 
	if (!e->set)

		return -EINVAL;



	ret = __sysfs_match_string(e->items, e->num_items, buf);

	ret = iio_sysfs_match_string_with_gaps(e->items, e->num_items, buf);

	if (ret < 0)

		return ret;