diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/iio/consumer.h | 37 | ||||
| -rw-r--r-- | include/linux/minmax.h | 64 |
2 files changed, 91 insertions, 10 deletions
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h index 6802596b017c..e9910b41d48e 100644 --- a/include/linux/iio/consumer.h +++ b/include/linux/iio/consumer.h @@ -201,8 +201,9 @@ struct iio_dev * @chan: The channel being queried. * @val: Value read back. * - * Note raw reads from iio channels are in adc counts and hence - * scale will need to be applied if standard units required. + * Note, if standard units are required, raw reads from iio channels + * need the offset (default 0) and scale (default 1) to be applied + * as (raw + offset) * scale. */ int iio_read_channel_raw(struct iio_channel *chan, int *val); @@ -212,8 +213,9 @@ int iio_read_channel_raw(struct iio_channel *chan, * @chan: The channel being queried. * @val: Value read back. * - * Note raw reads from iio channels are in adc counts and hence - * scale will need to be applied if standard units required. + * Note, if standard units are required, raw reads from iio channels + * need the offset (default 0) and scale (default 1) to be applied + * as (raw + offset) * scale. * * In opposit to the normal iio_read_channel_raw this function * returns the average of multiple reads. @@ -281,8 +283,9 @@ int iio_read_channel_attribute(struct iio_channel *chan, int *val, * @chan: The channel being queried. * @val: Value being written. * - * Note raw writes to iio channels are in dac counts and hence - * scale will need to be applied if standard units required. + * Note that for raw writes to iio channels, if the value provided is + * in standard units, the affect of the scale and offset must be removed + * as (value / scale) - offset. */ int iio_write_channel_raw(struct iio_channel *chan, int val); @@ -292,12 +295,25 @@ int iio_write_channel_raw(struct iio_channel *chan, int val); * @chan: The channel being queried. * @val: Value read back. * - * Note raw reads from iio channels are in adc counts and hence - * scale will need to be applied if standard units are required. + * Note, if standard units are required, raw reads from iio channels + * need the offset (default 0) and scale (default 1) to be applied + * as (raw + offset) * scale. */ int iio_read_max_channel_raw(struct iio_channel *chan, int *val); /** + * iio_read_min_channel_raw() - read minimum available raw value from a given + * channel, i.e. the minimum possible value. + * @chan: The channel being queried. + * @val: Value read back. + * + * Note, if standard units are required, raw reads from iio channels + * need the offset (default 0) and scale (default 1) to be applied + * as (raw + offset) * scale. + */ +int iio_read_min_channel_raw(struct iio_channel *chan, int *val); + +/** * iio_read_avail_channel_raw() - read available raw values from a given channel * @chan: The channel being queried. * @vals: Available values read back. @@ -308,8 +324,9 @@ int iio_read_max_channel_raw(struct iio_channel *chan, int *val); * For ranges, three vals are always returned; min, step and max. * For lists, all the possible values are enumerated. * - * Note raw available values from iio channels are in adc counts and - * hence scale will need to be applied if standard units are required. + * Note, if standard units are required, raw available values from iio + * channels need the offset (default 0) and scale (default 1) to be applied + * as (raw + offset) * scale. */ int iio_read_avail_channel_raw(struct iio_channel *chan, const int **vals, int *length); diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 396df1121bff..798c6963909f 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -133,6 +133,70 @@ */ #define max_t(type, x, y) __careful_cmp((type)(x), (type)(y), >) +/* + * Remove a const qualifier from integer types + * _Generic(foo, type-name: association, ..., default: association) performs a + * comparison against the foo type (not the qualified type). + * Do not use the const keyword in the type-name as it will not match the + * unqualified type of foo. + */ +#define __unconst_integer_type_cases(type) \ + unsigned type: (unsigned type)0, \ + signed type: (signed type)0 + +#define __unconst_integer_typeof(x) typeof( \ + _Generic((x), \ + char: (char)0, \ + __unconst_integer_type_cases(char), \ + __unconst_integer_type_cases(short), \ + __unconst_integer_type_cases(int), \ + __unconst_integer_type_cases(long), \ + __unconst_integer_type_cases(long long), \ + default: (x))) + +/* + * Do not check the array parameter using __must_be_array(). + * In the following legit use-case where the "array" passed is a simple pointer, + * __must_be_array() will return a failure. + * --- 8< --- + * int *buff + * ... + * min = min_array(buff, nb_items); + * --- 8< --- + * + * The first typeof(&(array)[0]) is needed in order to support arrays of both + * 'int *buff' and 'int buff[N]' types. + * + * The array can be an array of const items. + * typeof() keeps the const qualifier. Use __unconst_integer_typeof() in order + * to discard the const qualifier for the __element variable. + */ +#define __minmax_array(op, array, len) ({ \ + typeof(&(array)[0]) __array = (array); \ + typeof(len) __len = (len); \ + __unconst_integer_typeof(__array[0]) __element = __array[--__len]; \ + while (__len--) \ + __element = op(__element, __array[__len]); \ + __element; }) + +/** + * min_array - return minimum of values present in an array + * @array: array + * @len: array length + * + * Note that @len must not be zero (empty array). + */ +#define min_array(array, len) __minmax_array(min, array, len) + +/** + * max_array - return maximum of values present in an array + * @array: array + * @len: array length + * + * Note that @len must not be zero (empty array). + */ +#define max_array(array, len) __minmax_array(max, array, len) + /** * clamp_t - return a value clamped to a given range using a given type * @type: the type of variable to use |