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docs: fpga: mgr: document parse_header() callback
Document newly introduced fpga_manager_ops callback parse_header() and
flag skip_header along with header_size and data_size fields of struct
fpga_image_info.
Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20220623163248.3672-3-i.bornyakov@metrotek.ru
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
authored by
Ivan Bornyakov
and committed by
Xu Yilun
288cc44b
3cc624be
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Documentation/driver-api/fpga/fpga-mgr.rst
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Documentation/driver-api/fpga/fpga-mgr.rst
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success or negative error codes otherwise.
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The programming sequence is::
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1. .write_init
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2. .write or .write_sg (may be called once or multiple times)
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3. .write_complete
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1. .parse_header (optional, may be called once or multiple times)
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2. .write_init
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3. .write or .write_sg (may be called once or multiple times)
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4. .write_complete
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The .write_init function will prepare the FPGA to receive the image data. The
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buffer passed into .write_init will be at most .initial_header_size bytes long;
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The .parse_header function will set header_size and data_size to
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struct fpga_image_info. Before parse_header call, header_size is initialized
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with initial_header_size. If flag skip_header of fpga_manager_ops is true,
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.write function will get image buffer starting at header_size offset from the
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beginning. If data_size is set, .write function will get data_size bytes of
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the image buffer, otherwise .write will get data up to the end of image buffer.
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This will not affect .write_sg, .write_sg will still get whole image in
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sg_table form. If FPGA image is already mapped as a single contiguous buffer,
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whole buffer will be passed into .parse_header. If image is in scatter-gather
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form, core code will buffer up at least .initial_header_size before the first
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call of .parse_header, if it is not enough, .parse_header should set desired
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size into info->header_size and return -EAGAIN, then it will be called again
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with greater part of image buffer on the input.
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The .write_init function will prepare the FPGA to receive the image data. The
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buffer passed into .write_init will be at least info->header_size bytes long;
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if the whole bitstream is not immediately available then the core code will
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buffer up at least this much before starting.
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