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authorLinus Torvalds <torvalds@linux-foundation.org>2018-10-26 09:11:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-26 09:11:43 -0700
commit18d0eae30e6a4f8644d589243d7ac1d70d29203d (patch)
treefef5a78d54b8763cb17867018356cfe311b31036 /Documentation/driver-api/fpga/fpga-programming.rst
parent26873acacbdbb4e4b444f5dd28dcc4853f0e8ba2 (diff)
parent14fdc2c5318ae420e68496975f48dc1dbef52649 (diff)
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Merge tag 'char-misc-4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH: "Here is the big set of char/misc patches for 4.20-rc1. Loads of things here, we have new code in all of these driver subsystems: - fpga - stm - extcon - nvmem - eeprom - hyper-v - gsmi - coresight - thunderbolt - vmw_balloon - goldfish - soundwire along with lots of fixes and minor changes to other small drivers. All of these have been in linux-next for a while with no reported issues" * tag 'char-misc-4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (245 commits) Documentation/security-bugs: Clarify treatment of embargoed information lib: Fix ia64 bootloader linkage MAINTAINERS: Clarify UIO vs UIOVEC maintainer docs/uio: fix a grammar nitpick docs: fpga: document programming fpgas using regions fpga: add devm_fpga_region_create fpga: bridge: add devm_fpga_bridge_create fpga: mgr: add devm_fpga_mgr_create hv_balloon: Replace spin_is_locked() with lockdep sgi-xp: Replace spin_is_locked() with lockdep eeprom: New ee1004 driver for DDR4 memory eeprom: at25: remove unneeded 'at25_remove' w1: IAD Register is yet readable trough iad sys file. Fix snprintf (%u for unsigned, count for max size). misc: mic: scif: remove set but not used variables 'src_dma_addr, dst_dma_addr' misc: mic: fix a DMA pool free failure platform: goldfish: pipe: Add a blank line to separate varibles and code platform: goldfish: pipe: Remove redundant casting platform: goldfish: pipe: Call misc_deregister if init fails platform: goldfish: pipe: Move the file-scope goldfish_pipe_dev variable into the driver state platform: goldfish: pipe: Move the file-scope goldfish_pipe_miscdev variable into the driver state ...
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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 :c:func:`fpga_region_program_fpga()`.
+
+:c:func:`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:member:`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 :c:func:`fpga_image_info_alloc()` and freed with
+:c:func:`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);
+
+ }
+
+ /* Add info to region and do the programming */
+ region->info = info;
+ ret = fpga_region_program_fpga(region);
+
+ /* Deallocate the image info if you're done with it */
+ region->info = NULL;
+ fpga_image_info_free(info);
+
+ if (ret)
+ return ret;
+
+ /* Now enumerate whatever hardware has appeared in the FPGA. */
+
+API for programming an FPGA
+---------------------------
+
+* :c:func:`fpga_region_program_fpga` — Program an FPGA
+* :c:type:`fpga_image_info` — Specifies what FPGA image to program
+* :c:func:`fpga_image_info_alloc()` — Allocate an FPGA image info struct
+* :c:func:`fpga_image_info_free()` — Free an FPGA image info struct
+
+.. kernel-doc:: drivers/fpga/fpga-region.c
+ :functions: fpga_region_program_fpga
+
+FPGA Manager flags
+
+.. kernel-doc:: include/linux/fpga/fpga-mgr.h
+ :doc: FPGA Manager flags
+
+.. kernel-doc:: include/linux/fpga/fpga-mgr.h
+ :functions: fpga_image_info
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+ :functions: fpga_image_info_alloc
+
+.. kernel-doc:: drivers/fpga/fpga-mgr.c
+ :functions: fpga_image_info_free
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