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iio: Handle enumerated properties with gaps

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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: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210107112049.10815-1-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Lars-Peter Clausen 2021-01-07 13:20:49 +02:00 committed by Jonathan Cameron
parent 3cc718bc79
commit d9a0e73c0c
1 changed files with 36 additions and 3 deletions
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39
drivers/iio/industrialio-core.c
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@ -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;