374956600e
We already do have the length field in the struct iio_buffer which is expected to be in sync with the current size of the buffer. And currently all implementations of the get_length callback either return this field or a constant number. This patch removes the get_length callback and replaces all occurrences in the IIO core with directly accessing the length field of the buffer. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
48 lines
1.8 KiB
Plaintext
48 lines
1.8 KiB
Plaintext
Buffer support within IIO
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This document is intended as a general overview of the functionality
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a buffer may supply and how it is specified within IIO. For more
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specific information on a given buffer implementation, see the
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comments in the source code. Note that some drivers allow buffer
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implementation to be selected at compile time via Kconfig options.
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A given buffer implementation typically embeds a struct
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iio_ring_buffer and it is a pointer to this that is provided to the
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IIO core. Access to the embedding structure is typically done via
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container_of functions.
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struct iio_ring_buffer contains a struct iio_ring_setup_ops *setup_ops
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which in turn contains the 4 function pointers
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(preenable, postenable, predisable and postdisable).
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These are used to perform device specific steps on either side
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of the core changing its current mode to indicate that the buffer
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is enabled or disabled (along with enabling triggering etc. as appropriate).
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Also in struct iio_ring_buffer is a struct iio_ring_access_funcs.
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The function pointers within here are used to allow the core to handle
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as much buffer functionality as possible. Note almost all of these
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are optional.
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store_to
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If possible, push data to the buffer.
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read_last
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If possible, get the most recent scan from the buffer (without removal).
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This provides polling like functionality whilst the ring buffering is in
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use without a separate read from the device.
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rip_first_n
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The primary buffer reading function. Note that it may well not return
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as much data as requested.
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request_update
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If parameters have changed that require reinitialization or configuration of
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the buffer this will trigger it.
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set_bytes_per_datum
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Set the number of bytes for a complete scan. (All samples + timestamp)
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set_length
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Set the number of complete scans that may be held by the buffer.
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