[PATCH v4 0/3] fpga: xilinx-selectmap: add new driver

[Charles Perry]

Hello,

This patchset adds a new driver for the 7 series FPGA's SelectMAP
interface.

The SelectMAP interface shares a common GPIO protocol with the SPI
interface which is already in the kernel (drivers/fpga/xilinx-spi.c).
The approach proposed in this patchset is to refactor xilinx-spi.c into
xilinx-core.c which would handle the common GPIO protocol. This is then
used to build two drivers, the already existing xilinx-spi.c driver and
a newly added xilinx-selectmap.c driver.

The SelectMAP driver proposed only supports 8 bit mode. This is because
the 16 and 32 bits mode have limitations with regards to compressed
bitstream support as well as introducing endianness considerations.

I'm testing xilinx-selectmap.c on a custom i.MX6 board connected to an
Artix 7 FPGA. Flashing a 913K bitstream takes 0.44 seconds.

Changes since v3: (from Rob Herring review)
 * Fix an error in the DT binding example compatible.
 * Drop the renaming of "prog_b" to "prog" and "init-b" to "init".
   Patches 2 and 3 are removed.

Changes since v2:
 * Inserted patch 2 and 3 which rename "prog_b" and "init-b" into "prog"
   and "init" for the SPI driver.
 * From Krzysztof Kozlowski review's:
   * Use more specific compatible names
   * Remove other missing occurences of the slave word missed in v2.
 * From Xu Yilun review's:
   * Fix vertical whitespace in get_done_gpio().
   * Combine write() and write_one_dummy_byte() together.
   * Eliminate most of the xilinx_core_probe() arguments, the driver
     needs to populate those directly into the xilinx_fpga_core struct.
     Added some documentation to struct xilinx_fpga_core to clarify
     this.
   * Removed typedefs from xilinx-core.h.
   * Moved null checks in xilinx_core_probe() to first patch.
   * Move csi_b and rdwr_b out of xilinx_selectmap_conf as they are not
     used out of the probe function.

Changes since v1: (from Krzysztof Kozlowski review's)
  * Use more conventional names for gpio DT bindings
  * fix example in DT bindings
  * add mc-peripheral-props.yaml to DT bindings
  * fix various formatting mistakes
  * Remove all occurences of the "slave" word.

Charles Perry (3):
  fpga: xilinx-spi: extract a common driver core
  dt-bindings: fpga: xlnx,fpga-selectmap: add DT schema
  fpga: xilinx-selectmap: add new driver

 .../bindings/fpga/xlnx,fpga-selectmap.yaml    |  86 +++++++
 drivers/fpga/Kconfig                          |  12 +
 drivers/fpga/Makefile                         |   2 +
 drivers/fpga/xilinx-core.c                    | 208 +++++++++++++++++
 drivers/fpga/xilinx-core.h                    |  28 +++
 drivers/fpga/xilinx-selectmap.c               |  97 ++++++++
 drivers/fpga/xilinx-spi.c                     | 212 ++----------------
 7 files changed, 446 insertions(+), 199 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/fpga/xlnx,fpga-selectmap.yaml
 create mode 100644 drivers/fpga/xilinx-core.c
 create mode 100644 drivers/fpga/xilinx-core.h
 create mode 100644 drivers/fpga/xilinx-selectmap.c

--
2.43.0