diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index 4fc9f6bd4281..851cfe4f0a05 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -1510,21 +1510,24 @@ Contact: linux-iio@vger.kernel.org Description: Description of the scan element data storage within the buffer and hence the form in which it is read from user-space. - Form is [be|le]:[s|u]bits/storagebits[>>shift]. - be or le specifies big or little endian. s or u specifies if - signed (2's complement) or unsigned. bits is the number of bits - of data and storagebits is the space (after padding) that it - occupies in the buffer. shift if specified, is the shift that - needs to be applied prior to masking out unused bits. Some - devices put their data in the middle of the transferred elements - with additional information on both sides. Note that some - devices will have additional information in the unused bits - so to get a clean value, the bits value must be used to mask - the buffer output value appropriately. The storagebits value - also specifies the data alignment. So s48/64>>2 will be a - signed 48 bit integer stored in a 64 bit location aligned to - a 64 bit boundary. To obtain the clean value, shift right 2 - and apply a mask to zero the top 16 bits of the result. + Form is [be|le]:[f|s|u]bits/storagebits[>>shift]. + be or le specifies big or little endian. f means floating-point + (IEEE 754 binary format), s means signed (2's complement), u means + unsigned. bits is the number of bits of data and storagebits is the + space (after padding) that it occupies in the buffer; when using a + floating-point format, bits must be one of the width values defined + in the IEEE 754 standard for binary interchange formats (e.g. 16 + indicates the binary16 format for half-precision numbers). shift, + if specified, is the shift that needs to be applied prior to + masking out unused bits. Some devices put their data in the middle + of the transferred elements with additional information on both + sides. Note that some devices will have additional information in + the unused bits, so to get a clean value the bits value must be + used to mask the buffer output value appropriately. The storagebits + value also specifies the data alignment. So s48/64>>2 will be a + signed 48 bit integer stored in a 64 bit location aligned to a 64 + bit boundary. To obtain the clean value, shift right 2 and apply a + mask to zero the top 16 bits of the result. For other storage combinations this attribute will be extended appropriately. diff --git a/Documentation/driver-api/iio/buffers.rst b/Documentation/driver-api/iio/buffers.rst index e16abaf826fe..8779022e3da5 100644 --- a/Documentation/driver-api/iio/buffers.rst +++ b/Documentation/driver-api/iio/buffers.rst @@ -37,9 +37,10 @@ directory contains attributes of the following form: * :file:`index`, the scan_index of the channel. * :file:`type`, description of the scan element data storage within the buffer and hence the form in which it is read from user space. - Format is [be|le]:[s|u]bits/storagebits[Xrepeat][>>shift] . + Format is [be|le]:[f|s|u]bits/storagebits[Xrepeat][>>shift] . * *be* or *le*, specifies big or little endian. + * *f*, specifies if floating-point. * *s* or *u*, specifies if signed (2's complement) or unsigned. * *bits*, is the number of valid data bits. * *storagebits*, is the number of bits (after padding) that it occupies in the diff --git a/Documentation/iio/iio_devbuf.rst b/Documentation/iio/iio_devbuf.rst index dca1f0200b0d..e91730fa3cea 100644 --- a/Documentation/iio/iio_devbuf.rst +++ b/Documentation/iio/iio_devbuf.rst @@ -83,9 +83,10 @@ and the relevant _type attributes to establish the data storage format. Read-only attribute containing the description of the scan element data storage within the buffer and hence the form in which it is read from userspace. Format -is [be|le]:[s|u]bits/storagebits[Xrepeat][>>shift], where: +is [be|le]:[f|s|u]bits/storagebits[Xrepeat][>>shift], where: - **be** or **le** specifies big or little-endian. +- **f** specifies if floating-point. - **s** or **u** specifies if signed (2's complement) or unsigned. - **bits** is the number of valid data bits. - **storagebits** is the number of bits (after padding) that it occupies in the diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index e03b7e912d7d..96b05c86c325 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -190,6 +190,13 @@ struct iio_event_spec { */ #define IIO_SCAN_FORMAT_UNSIGNED_INT 'u' +/** + * define IIO_SCAN_FORMAT_FLOAT - floating-point data format + * + * &iio_scan_type.format value for IEEE 754 floating-point numbers. + */ +#define IIO_SCAN_FORMAT_FLOAT 'f' + /** * struct iio_scan_type - specification for channel data format in buffer * @sign: Deprecated, use @format instead.