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author | Alan Tull <atull@kernel.org> | 2018-05-17 01:50:05 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-25 18:23:56 +0200 |
commit | fcc803956a4725dac790ddfce27f519ca6d84c60 (patch) | |
tree | 80d10c7389299ee557a63a908b05d83c0fb4b303 /Documentation/driver-api/fpga | |
parent | documentation: fpga: add bridge document to driver-api (diff) | |
download | linux-fcc803956a4725dac790ddfce27f519ca6d84c60.tar.xz linux-fcc803956a4725dac790ddfce27f519ca6d84c60.zip |
documentation: fpga: move fpga-region.txt to driver-api
Move Documentation/fpga/fpga-region.txt to
driver-api/fpga/fpga-region.rst. Including:
- Add it to driver-api/fpga/index.rst
- Formatting changes to build cleanly as ReST documentation
- Some rewrites for better flow as a ReST doc such as moving
API reference to the end of the doc
- Rewrite API reference section to refer to kernel-doc
documentation in fpga-region.c driver code
Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/driver-api/fpga')
-rw-r--r-- | Documentation/driver-api/fpga/fpga-region.rst | 102 | ||||
-rw-r--r-- | Documentation/driver-api/fpga/index.rst | 1 |
2 files changed, 103 insertions, 0 deletions
diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst new file mode 100644 index 000000000000..f89e4a311722 --- /dev/null +++ b/Documentation/driver-api/fpga/fpga-region.rst @@ -0,0 +1,102 @@ +FPGA Region +=========== + +Overview +-------- + +This document is meant to be an brief overview of the FPGA region API usage. A +more conceptual look at regions can be found in the Device Tree binding +document [#f1]_. + +For the purposes of this API document, let's just say that a region associates +an FPGA Manager and a bridge (or bridges) with a reprogrammable region of an +FPGA or the whole FPGA. The API provides a way to register a region and to +program a region. + +Currently the only layer above fpga-region.c in the kernel is the Device Tree +support (of-fpga-region.c) described in [#f1]_. The DT support layer uses regions +to program the FPGA and then DT to handle enumeration. The common region code +is intended to be used by other schemes that have other ways of accomplishing +enumeration after programming. + +An fpga-region can be set up to know the following things: + + * which FPGA manager to use to do the programming + + * which bridges to disable before programming and enable afterwards. + +Additional info needed to program the FPGA image is passed in the struct +fpga_image_info including: + + * pointers to the image as either a scatter-gather buffer, a contiguous + buffer, or the name of firmware file + + * flags indicating specifics such as whether the image if for partial + reconfiguration. + +How to program a FPGA using a region +------------------------------------ + +First, allocate the info struct:: + + info = fpga_image_info_alloc(dev); + if (!info) + return -ENOMEM; + +Set flags as needed, i.e.:: + + info->flags |= FPGA_MGR_PARTIAL_RECONFIG; + +Point to your FPGA image, such as:: + + info->sgt = &sgt; + +Add info to region and do the programming:: + + region->info = info; + ret = fpga_region_program_fpga(region); + +:c:func:`fpga_region_program_fpga()` operates on info passed in the +fpga_image_info (region->info). This function will attempt to: + + * lock the region's mutex + * lock 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 + * re-enable the bridges + * release the locks + +Then you will want to enumerate whatever hardware has appeared in the FPGA. + +How to add a new FPGA region +---------------------------- + +An example of usage can be seen in the probe function of [#f2]_. + +.. [#f1] ../devicetree/bindings/fpga/fpga-region.txt +.. [#f2] ../../drivers/fpga/of-fpga-region.c + +API to program a FGPA +--------------------- + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_program_fpga + +API to add a new FPGA region +---------------------------- + +.. kernel-doc:: include/linux/fpga/fpga-region.h + :functions: fpga_region + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_create + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_free + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_register + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_unregister diff --git a/Documentation/driver-api/fpga/index.rst b/Documentation/driver-api/fpga/index.rst index 968bbbfce0e8..c51e5ebd544a 100644 --- a/Documentation/driver-api/fpga/index.rst +++ b/Documentation/driver-api/fpga/index.rst @@ -10,3 +10,4 @@ FPGA Subsystem intro fpga-mgr fpga-bridge + fpga-region |