@@ -7,6 +7,7 @@ Authors:
- Enno Luebbers <enno.luebbers@intel.com>
- Xiao Guangrong <guangrong.xiao@linux.intel.com>
- Wu Hao <hao.wu@intel.com>
+- Xu Yilun <yilun.xu@intel.com>
The Device Feature List (DFL) FPGA framework (and drivers according to
this framework) hides the very details of low layer hardwares and provides
@@ -530,6 +531,30 @@ Being able to specify more than one DFL per BAR has been considered, but it
was determined the use case did not provide value. Specifying a single DFL
per BAR simplifies the implementation and allows for extra error checking.
+
+Userspace driver support for DFL devices
+========================================
+The purpose of an FPGA is to be reprogrammed with newly developed hardware
+components. New hardware can instantiate a new private feature in the DFL, and
+then present a DFL device in the system. In some cases users may need a
+userspace driver for the DFL device:
+
+* Users may need to run some diagnostic test for their hardware.
+* Users may prototype the kernel driver in user space.
+* Some hardware is designed for specific purposes and does not fit into one of
+ the standard kernel subsystems.
+
+This requires direct access to MMIO space and interrupt handling from
+userspace. The dfl-uio-pdev module exposes the UIO device interfaces for this
+purpose. It adds the uio_pdrv_genirq platform device with the resources of
+the DFL feature, and lets the generic UIO platform device driver provide UIO
+support to userspace.
+
+FPGA_DFL_UIO_PDEV should be selected to enable the dfl-uio-pdev module driver.
+To support a new DFL feature via UIO direct access, its feature id should be
+added to the driver's id_table.
+
+
Open discussion
===============
FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial reconfiguration
This patch adds description for UIO support for dfl devices on DFL bus. Signed-off-by: Xu Yilun <yilun.xu@intel.com> --- v2: no doc in v1, add it for v2. v3: some documentation fixes. v4: documentation change since the driver matching is changed. v5: no change. v6: improve the title of the userspace driver support section. some word improvement. v7: rebased to next-20210119 v8: some doc fixes. --- Documentation/fpga/dfl.rst | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)