In-kernel API for FPGA Programming
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==================================
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Overview
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--------
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The in-kernel API for FPGA programming is a combination of APIs from
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FPGA manager, bridge, and regions. The actual function used to
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trigger FPGA programming is fpga_region_program_fpga().
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fpga_region_program_fpga() uses functionality supplied by
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the FPGA manager and bridges. It will:
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* lock the region's mutex
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* lock the mutex of the region's FPGA manager
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* build a list of FPGA bridges if a method has been specified to do so
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* disable the bridges
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* program the FPGA using info passed in :c:expr:`fpga_region->info`.
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* re-enable the bridges
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* release the locks
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The struct fpga_image_info specifies what FPGA image to program. It is
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allocated/freed by fpga_image_info_alloc() and freed with
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fpga_image_info_free()
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How to program an FPGA using a region
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-------------------------------------
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When the FPGA region driver probed, it was given a pointer to an FPGA manager
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driver so it knows which manager to use. The region also either has a list of
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bridges to control during programming or it has a pointer to a function that
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will generate that list. Here's some sample code of what to do next::
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#include <linux/fpga/fpga-mgr.h>
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#include <linux/fpga/fpga-region.h>
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struct fpga_image_info *info;
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int ret;
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/*
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* First, alloc the struct with information about the FPGA image to
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* program.
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*/
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info = fpga_image_info_alloc(dev);
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if (!info)
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return -ENOMEM;
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/* Set flags as needed, such as: */
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info->flags = FPGA_MGR_PARTIAL_RECONFIG;
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/*
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* Indicate where the FPGA image is. This is pseudo-code; you're
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* going to use one of these three.
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*/
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if (image is in a scatter gather table) {
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info->sgt = [your scatter gather table]
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} else if (image is in a buffer) {
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info->buf = [your image buffer]
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info->count = [image buffer size]
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} else if (image is in a firmware file) {
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info->firmware_name = devm_kstrdup(dev, firmware_name,
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GFP_KERNEL);
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}
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/* Add info to region and do the programming */
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region->info = info;
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ret = fpga_region_program_fpga(region);
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/* Deallocate the image info if you're done with it */
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region->info = NULL;
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fpga_image_info_free(info);
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if (ret)
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return ret;
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/* Now enumerate whatever hardware has appeared in the FPGA. */
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API for programming an FPGA
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---------------------------
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* fpga_region_program_fpga() — Program an FPGA
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* fpga_image_info() — Specifies what FPGA image to program
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* fpga_image_info_alloc() — Allocate an FPGA image info struct
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* fpga_image_info_free() — Free an FPGA image info struct
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.. kernel-doc:: drivers/fpga/fpga-region.c
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:functions: fpga_region_program_fpga
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FPGA Manager flags
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:doc: FPGA Manager flags
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.. kernel-doc:: include/linux/fpga/fpga-mgr.h
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:functions: fpga_image_info
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_image_info_alloc
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.. kernel-doc:: drivers/fpga/fpga-mgr.c
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:functions: fpga_image_info_free
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