Documentation/driver-api/fpga/fpga-programming.rst

Source file repositories/reference/linux-study-clean/Documentation/driver-api/fpga/fpga-programming.rst

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Documentation/driver-api/fpga/fpga-programming.rst
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In-kernel API for FPGA Programming
==================================

Overview
--------

The in-kernel API for FPGA programming is a combination of APIs from
FPGA manager, bridge, and regions.  The actual function used to
trigger FPGA programming is fpga_region_program_fpga().

fpga_region_program_fpga() uses functionality supplied by
the FPGA manager and bridges.  It will:

 * lock the region's mutex
 * lock the mutex of the region's FPGA manager
 * build a list of FPGA bridges if a method has been specified to do so
 * disable the bridges
 * program the FPGA using info passed in :c:expr:`fpga_region->info`.
 * re-enable the bridges
 * release the locks

The struct fpga_image_info specifies what FPGA image to program.  It is
allocated/freed by fpga_image_info_alloc() and freed with
fpga_image_info_free()

How to program an FPGA using a region
-------------------------------------

When the FPGA region driver probed, it was given a pointer to an FPGA manager
driver so it knows which manager to use.  The region also either has a list of
bridges to control during programming or it has a pointer to a function that
will generate that list.  Here's some sample code of what to do next::

	#include <linux/fpga/fpga-mgr.h>
	#include <linux/fpga/fpga-region.h>

	struct fpga_image_info *info;
	int ret;

	/*
	 * First, alloc the struct with information about the FPGA image to
	 * program.
	 */
	info = fpga_image_info_alloc(dev);
	if (!info)
		return -ENOMEM;

	/* Set flags as needed, such as: */
	info->flags = FPGA_MGR_PARTIAL_RECONFIG;

	/*
	 * Indicate where the FPGA image is. This is pseudo-code; you're
	 * going to use one of these three.
	 */
	if (image is in a scatter gather table) {

		info->sgt = [your scatter gather table]

	} else if (image is in a buffer) {

		info->buf = [your image buffer]
		info->count = [image buffer size]

	} else if (image is in a firmware file) {

		info->firmware_name = devm_kstrdup(dev, firmware_name,
						   GFP_KERNEL);

	}

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Implementation Notes