From 7985e7c1003bc5cdfa20755f8cfdada946ed8e18 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Fri, 14 Sep 2012 16:21:00 +0100 Subject: iio: Introduce a new fractional value type Currently IIO uses a decimal fixed point representations for real type numbers. This patch introduces a new representation for rational type numbers. The number will be expressed by specifying a numerator and denominator. For converting a raw value to a processed value multiply it by the numerator and divide it by the denominator. The reasoning for introducing this new type is that for a lot of devices the scale can be represented easily by a fractional number, but it is not possible to represent it as fixed point number without rounding. E.g. for a simple DAC the scale is often the reference voltage divided by the number of possible values (Usually 2**n_bits - 1). Each driver currently implements the conversion of this fraction to a fixed point number on its own. Also when it comes to the in-kernel interface this allows to directly use the fractional factors to convert a raw value to a processed value. This should on one hand require less instructions and on the other hand increase the precision. Signed-off-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- include/linux/iio/types.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/iio') diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h index 44e397705d7f..5c647ecfd5ba 100644 --- a/include/linux/iio/types.h +++ b/include/linux/iio/types.h @@ -57,5 +57,6 @@ enum iio_modifier { #define IIO_VAL_INT_PLUS_MICRO 2 #define IIO_VAL_INT_PLUS_NANO 3 #define IIO_VAL_INT_PLUS_MICRO_DB 4 +#define IIO_VAL_FRACTIONAL 10 #endif /* _IIO_TYPES_H_ */ -- cgit v1.2.2