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Diffstat (limited to 'drivers/staging/iio/Documentation/userspace.txt')
| -rw-r--r-- | drivers/staging/iio/Documentation/userspace.txt | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/drivers/staging/iio/Documentation/userspace.txt b/drivers/staging/iio/Documentation/userspace.txt new file mode 100644 index 000000000000..661015a0b866 --- /dev/null +++ b/drivers/staging/iio/Documentation/userspace.txt @@ -0,0 +1,60 @@ +Userspace access to IIO + +Example, ST Microelectronics LIS3L02DQ accelerometer. + +Typical sysfs entries (pruned for clarity) + +/sys/class/iio + device0 - iio_dev related elements + name - driver specific identifier (here lis3l02dq) + accel_x - polled (or from ring) raw readout of acceleration + accel_x_gain - hardware gain (calibration) + accel_x_offset - hardware offset (calibration) + available_sampling_frequency + + available_sampling_frequency - what options are there + sampling_frequency - control of internal sampling frequency + scan_elements - controls which channels will be stored in the ring buffer + scan_en_accel_x + scan_en_accel_y + scan_en_timestamp + device - link to underlying hardware device + uevent - udev related element + + thresh - unified threshold used for detection on all axis + event_line0_sources - which events are enabled + accel_x_high - enable x axis high threshold event + accel_x_low - enable x axis low threshold event + + event_line0 - event interface + dev - major:minor for the chrdev (note major allocation dynamic) + trigger - consumer attachement + current_trigger - name based association with a trigger + ring_buffer0 - ring buffer interface + bps - byptes per sample (read only), dependant on scan element selection + length - (rw) specificy length fo software ring buffer (typically ro in hw case) + ring_enable - turn the ring on. If its the first to be enabled attached to this + trigger will also enable the trigger. + ring_access0 + dev - major:minor for ring buffer access chrdev + ring_event_line0 + dev - major:minor for ring buffer event chrdev + + trigger0 - data ready trigger elements + name - unqiue name of trigger + +Udev will create the following entries under /dev by default: + +ring_access0 - ring access chrdev +ring_event0 - ring event chrdev +event_line0 - general event chrdev. + +For the example code we assume the following rules have been used to ensure +unique and consistent naming of these for the lis3l02dq in question: + +KERNEL="ring_event_line*", ID="spi1.0", DRIVER="lis3l02dq", NAME="iio/lis3l02dq_ring_event" +KERNEL="event_line*", ID="spi1.0", DRIVER="lis3l02dq", NAME="iio/lis3l02dq_event" +KERNEL="ring_access*", ID="spi1.0", DRIVER="lis3l02dq", NAME="iio/lis3l02dq_ring_access" + +The files, lis3l02dqbuffersimple.c and iio_util.h in this directory provide an example +of how to use the ring buffer and event interfaces. |