Re: FPGA Region enhancements and fixes

From: Alan Tull
Date: Tue Feb 28 2017 - 17:57:45 EST


On Tue, Feb 28, 2017 at 11:35 AM, Alan Tull <delicious.quinoa@xxxxxxxxx> wrote:
> On Wed, Feb 15, 2017 at 10:14 AM, Alan Tull <atull@xxxxxxxxxx> wrote:
>> This patchset intends to enable expanding the use of FPGA regions
>> beyond device tree overlays. Also one fix for the existing DTO
>> implementation. It's an RFC, looking for feedback, also I need
>> to do more testing and fix it working for modules.
>
> There's a lot of stuff to look at here. To make it easier, I've pushed a
> branch to the linux-fpga repo. Branch name is
> next-20170228-rfc-atull-20170210
>
> Alan
>
>>
>> Patch 1 adds a function so the caller could program the fpga from
>> either a scatter gather table, a buffer, or a firmware file. The
>> parameters are passed in the fpga_image_info struct. This way works,
>> but there may be a better or more widely accepted way. Maybe they
>> should be a union? If someone knows of a well written example in the
>> kernel for me to emulate, that would be really appreciated.
>>
>> Patch 2 is a fix for if you write > 1 overlay to a region.
>> It keeps track of overlays in a list.
>>
>> Patch 3 adds functions for working with FPGA bridges using the
>> device rather than the device node (for non DT use).
>>
>> Patches 4-5 separate finding and locking a FPGA manager. So someone
>> could get a reference for a FPGA manager without locking it for
>> exclusive use.
>>
>> Patch 6 breaks up fpga-region.c into two files, moving the DT overlay
>> support to of-fpga-region.c. The functions exported by fpga-region.c
>> will enable code that creates an FPGA region and tell it what manager
>> and bridge to use. fpga-region.c doesn't do enumeration so whatever
>> code creates the region will also still have the responsibility to do
>> some enumeration after programming.
>>
>> Patches 7-8 a sysfs interface to FPGA regions. I'm sure this will be
>> controversial as discussions about FPGA userspace interfaces have
>> incited lively discussion in the past. The nice thing about this
>> interface is that it handles the dance of disabling the bridge before
>> programming and reenabling it afterwards. But no enumeration.
>> I post it as separate patch and document so the rest of the patches
>> could go forward while we hash out what a good non-DT interface
>> may look like if there is some other layer that is requesting
>> reprogramming and handling enumeration.
>>
>> I've tested it lightly and believe that each patch separately
>> builds and works.
>>
>> Known issues: doesn't work as a module anymore. I'll be fixing that.

Actually just reran my tests and these *do* work as a modules.

Alan

>>
>> Alan
>>
>> Alan Tull (8):
>> fpga-mgr: add a single function for fpga loading methods
>> fpga-region: support more than one overlay per FPGA region
>> fpga-bridge: add non-dt support
>> doc: fpga-mgr: separate getting/locking FPGA manager
>> fpga-mgr: separate getting/locking FPGA manager
>> fpga-region: separate out common code to allow non-dt support
>> fpga-region: add sysfs interface
>> doc: fpga: add sysfs document for fpga region
>>
>> Documentation/ABI/testing/sysfs-class-fpga-region | 26 +
>> Documentation/fpga/fpga-mgr.txt | 19 +-
>> drivers/fpga/Kconfig | 20 +-
>> drivers/fpga/Makefile | 1 +
>> drivers/fpga/fpga-bridge.c | 107 +++-
>> drivers/fpga/fpga-mgr.c | 56 +-
>> drivers/fpga/fpga-region.c | 725 ++++++++++------------
>> drivers/fpga/fpga-region.h | 68 ++
>> drivers/fpga/of-fpga-region.c | 510 +++++++++++++++
>> include/linux/fpga/fpga-bridge.h | 7 +-
>> include/linux/fpga/fpga-mgr.h | 17 +
>> 11 files changed, 1128 insertions(+), 428 deletions(-)
>> create mode 100644 Documentation/ABI/testing/sysfs-class-fpga-region
>> create mode 100644 drivers/fpga/fpga-region.h
>> create mode 100644 drivers/fpga/of-fpga-region.c
>>
>> --
>> 2.7.4
>>