[PATCH v22 2/5] docs: fpga: mgr: document parse_header() callback
From: Ivan Bornyakov <hidden>
Date: 2022-06-23 16:34:03
Also in:
linux-devicetree, linux-fpga, lkml
Subsystem:
documentation, fpga manager framework, the rest · Maintainers:
Jonathan Corbet, Moritz Fischer, Xu Yilun, Linus Torvalds
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 <redacted> Acked-by: Xu Yilun <yilun.xu@intel.com> --- Documentation/driver-api/fpga/fpga-mgr.rst | 27 +++++++++++++++++----- 1 file changed, 21 insertions(+), 6 deletions(-)
diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst
index 42c01f396dce..49c0a9512653 100644
--- a/Documentation/driver-api/fpga/fpga-mgr.rst
+++ b/Documentation/driver-api/fpga/fpga-mgr.rst@@ -79,12 +79,27 @@ do the programming sequence for this particular FPGA. These ops return 0 for success or negative error codes otherwise. The programming sequence is:: - 1. .write_init - 2. .write or .write_sg (may be called once or multiple times) - 3. .write_complete - -The .write_init function will prepare the FPGA to receive the image data. The -buffer passed into .write_init will be at most .initial_header_size bytes long; + 1. .parse_header (optional, may be called once or multiple times) + 2. .write_init + 3. .write or .write_sg (may be called once or multiple times) + 4. .write_complete + +The .parse_header function will set header_size and data_size to +struct fpga_image_info. Before parse_header call, header_size is initialized +with initial_header_size. If flag skip_header of fpga_manager_ops is true, +.write function will get image buffer starting at header_size offset from the +beginning. If data_size is set, .write function will get data_size bytes of +the image buffer, otherwise .write will get data up to the end of image buffer. +This will not affect .write_sg, .write_sg will still get whole image in +sg_table form. If FPGA image is already mapped as a single contiguous buffer, +whole buffer will be passed into .parse_header. If image is in scatter-gather +form, core code will buffer up at least .initial_header_size before the first +call of .parse_header, if it is not enough, .parse_header should set desired +size into info->header_size and return -EAGAIN, then it will be called again +with greater part of image buffer on the input. + +The .write_init function will prepare the FPGA to receive the image data. The +buffer passed into .write_init will be at least info->header_size bytes long; if the whole bitstream is not immediately available then the core code will buffer up at least this much before starting.
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2.36.1