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authorLars-Peter Clausen <lars@metafoo.de>2012-09-14 16:21:00 +0100
committerJonathan Cameron <jic23@kernel.org>2012-09-15 10:12:22 +0100
commit7985e7c1003bc5cdfa20755f8cfdada946ed8e18 (patch)
tree94adb3cf91ec3406361c2bc9d0c66485e1bf2436 /include
parentca7d1b32d2a0d4c62533b9401cf9ce4d14d183f7 (diff)
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 <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/iio/types.h1
1 files changed, 1 insertions, 0 deletions
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_ */