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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: 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>
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@ -169,6 +169,36 @@ static const char * const iio_chan_info_postfix[] = {
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[IIO_CHAN_INFO_CALIBAMBIENT] = "calibambient",
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};
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/**
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* iio_sysfs_match_string_with_gaps - matches given string in an array with gaps
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* @array: array of strings
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* @n: number of strings in the array
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* @str: string to match with
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*
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* Returns index of @str in the @array or -EINVAL, similar to match_string().
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* Uses sysfs_streq instead of strcmp for matching.
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*
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* This routine will look for a string in an array of strings.
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* The search will continue until the element is found or the n-th element
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* is reached, regardless of any NULL elements in the array.
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*/
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static int iio_sysfs_match_string_with_gaps(const char * const *array, size_t n,
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const char *str)
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{
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const char *item;
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int index;
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for (index = 0; index < n; index++) {
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item = array[index];
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if (!item)
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continue;
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if (sysfs_streq(item, str))
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return index;
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}
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return -EINVAL;
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}
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#if defined(CONFIG_DEBUG_FS)
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/*
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* There's also a CONFIG_DEBUG_FS guard in include/linux/iio/iio.h for
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@ -470,8 +500,11 @@ ssize_t iio_enum_available_read(struct iio_dev *indio_dev,
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if (!e->num_items)
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return 0;
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for (i = 0; i < e->num_items; ++i)
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for (i = 0; i < e->num_items; ++i) {
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if (!e->items[i])
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continue;
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len += scnprintf(buf + len, PAGE_SIZE - len, "%s ", e->items[i]);
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}
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/* replace last space with a newline */
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buf[len - 1] = '\n';
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@ -492,7 +525,7 @@ ssize_t iio_enum_read(struct iio_dev *indio_dev,
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i = e->get(indio_dev, chan);
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if (i < 0)
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return i;
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else if (i >= e->num_items)
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else if (i >= e->num_items || !e->items[i])
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return -EINVAL;
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return snprintf(buf, PAGE_SIZE, "%s\n", e->items[i]);
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@ -509,7 +542,7 @@ ssize_t iio_enum_write(struct iio_dev *indio_dev,
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if (!e->set)
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return -EINVAL;
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ret = __sysfs_match_string(e->items, e->num_items, buf);
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ret = iio_sysfs_match_string_with_gaps(e->items, e->num_items, buf);
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if (ret < 0)
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return ret;
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