From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH v9 2/7] staging: usage documentation for simple fpga bus Date: Fri, 17 Jul 2015 10:51:12 -0500 Message-ID: <1437148277-5405-3-git-send-email-atull@opensource.altera.com> References: <1437148277-5405-1-git-send-email-atull@opensource.altera.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1437148277-5405-1-git-send-email-atull@opensource.altera.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" To: gregkh@linuxfoundation.org, jgunthorpe@obsidianresearch.com, hpa@zytor.com, monstr@monstr.eu, michal.simek@xilinx.com, rdunlap@infradead.org Cc: mark.rutland@arm.com, linux-doc@vger.kernel.org, rubini@gnudd.com, pantelis.antoniou@konsulko.com, s.trumtrar@pengutronix.de, devel@driverdev.osuosl.org, sameo@linux.intel.com, nico@linaro.org, ijc+devicetree@hellion.org.uk, kyle.teske@ni.com, grant.likely@linaro.org, davidb@codeaurora.org, linus.walleij@linaro.org, cesarb@cesarb.net, devicetree@vger.kernel.org, jason@lakedaemon.net, pawel.moll@arm.com, iws@ovro.caltech.edu, Alan Tull , broonie@kernel.org, philip@balister.org, Petr Cvek , dinguyen@opensource.altera.com, pavel@denx.de, yvanderv@opensource.altera.com, linux-kernel@vger.kernel.org, balbi@ti.com, delicious.quinoa@gmail.com, robh+dt@kernel.org, rob@landley.net, galak@codeaurora.org, akpm@linux-foundation.org, davem@davemloft.net, m.chehab@samsung.com List-Id: devicetree@vger.kernel.org From: Alan Tull Add a document spelling out usage of the simple fpga bus. Signed-off-by: Alan Tull --- .../staging/fpga/Documentation/simple-fpga-bus.txt | 48 ++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 drivers/staging/fpga/Documentation/simple-fpga-bus.txt diff --git a/drivers/staging/fpga/Documentation/simple-fpga-bus.txt b/drivers/staging/fpga/Documentation/simple-fpga-bus.txt new file mode 100644 index 0000000..9df519f --- /dev/null +++ b/drivers/staging/fpga/Documentation/simple-fpga-bus.txt @@ -0,0 +1,48 @@ + Simple FPGA Bus + + Alan Tull 2015 + + Overview + -------- +The simple FPGA bus adds device tree overlay support for FPGA's. Loading a +DT overlay will result in the FGPA getting an image loaded, its bridges will +be released, and the DT populated for nodes below the simple-fpga-bus. This +results in drivers getting probed for the hardware that just got added. This +is intended to support the FPGA usage where the FPGA has hardware that +requires drivers. Removing the overlay will result in the drivers getting +removed and the bridges being disabled. + + + Requirements + ------------ + 1. An FPGA image that has a hardware block or blocks that use drivers that are + supported in the kernel. + 2. A device tree overlay. + 3. A FPGA manager driver supporting writing the FPGA. + 4. FPGA bridge resets supported as reset controllers. + +The DT overlay includes bindings (documented in bindings/simple-fpga-bus.txt) +that specify: + * Which fpga manager to use + * Which image file to load + * Flags indicating whether this this image is for full reconfiguration or + partial. + * a list of resets that should be released. These enable the FPGA bridges. + * child nodes specifying the devices that will be added with appropriate + compatible strings, etc. + +Since this code uses the firmware interface to get the image and DT overlay, +they currently have to be files on the filesystem. It doesn't have to be that +way forever as DT bindings could be added to point to other sources for the +image. + + + Sequence + -------- + 1. Load the DT overlay. One convenient way to do that is to use Pantelis' + handy configfs interface (more below). + 2. The simple FPGA bus gets probed and will do the following: + a. call the fpga manager core to program the FPGA + b. release the FPGA bridges + c. call of_platform_populate resulting in device drivers getting probed. + -- 1.7.9.5