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Diffstat (limited to 'Documentation/driver-api/iio/buffers.rst')
| -rw-r--r-- | Documentation/driver-api/iio/buffers.rst | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/Documentation/driver-api/iio/buffers.rst b/Documentation/driver-api/iio/buffers.rst index 02c99a6bee18..63f364e862d1 100644 --- a/Documentation/driver-api/iio/buffers.rst +++ b/Documentation/driver-api/iio/buffers.rst @@ -2,7 +2,7 @@ Buffers ======= -* struct :c:type:`iio_buffer` — general buffer structure +* struct iio_buffer — general buffer structure * :c:func:`iio_validate_scan_mask_onehot` — Validates that exactly one channel is selected * :c:func:`iio_buffer_get` — Grab a reference to the buffer @@ -15,8 +15,8 @@ trigger source. Multiple data channels can be read at once from IIO buffer sysfs interface ========================== An IIO buffer has an associated attributes directory under -:file:`/sys/bus/iio/iio:device{X}/buffer/*`. Here are some of the existing -attributes: +:file:`/sys/bus/iio/devices/iio:device{X}/buffer/*`. Here are some of the +existing attributes: * :file:`length`, the total number of data samples (capacity) that can be stored by the buffer. @@ -26,26 +26,28 @@ IIO buffer setup ================ The meta information associated with a channel reading placed in a buffer is -called a scan element . The important bits configuring scan elements are +called a scan element. The important bits configuring scan elements are exposed to userspace applications via the -:file:`/sys/bus/iio/iio:device{X}/scan_elements/*` directory. This file contains -attributes of the following form: +:file:`/sys/bus/iio/devices/iio:device{X}/scan_elements/` directory. This +directory contains attributes of the following form: * :file:`enable`, used for enabling a channel. If and only if its attribute is non *zero*, then a triggered capture will contain data samples for this channel. +* :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/storagebitsXrepeat[>>shift] . + Format is [be|le]:[s|u]bits/storagebits[Xrepeat][>>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 valid data bits. * *storagebits*, is the number of bits (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. + buffer. * *repeat*, specifies the number of bits/storagebits repetitions. When the - repeat element is 0 or 1, then the repeat value is omitted. + repeat element is 0 or 1, then the repeat value is omitted. + * *shift*, if specified, is the shift that needs to be applied prior to + masking out unused bits. For example, a driver for a 3-axis accelerometer with 12 bit resolution where data is stored in two 8-bits registers as follows:: @@ -88,7 +90,7 @@ fields in iio_chan_spec definition:: The driver implementing the accelerometer described above will have the following channel definition:: - struct struct iio_chan_spec accel_channels[] = { + struct iio_chan_spec accel_channels[] = { { .type = IIO_ACCEL, .modified = 1, @@ -122,4 +124,3 @@ More details .. kernel-doc:: include/linux/iio/buffer.h .. kernel-doc:: drivers/iio/industrialio-buffer.c :export: - |