[PATCH v6 0/4] 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 v5: (from Yilun review)
 * xilinx-core.h: remove private fields kernel-doc
 * xilinx-spi.c: rename conf into core in xilinx_spi_probe
 * xilinx-core.c: introduce the new gpio names in patch 4/4
 * xilinx-core.c: remove kernel-doc on xilinx_core_devm_gpiod_get()
 * xilinx-selectmap.c:
   * reorder includes in alphabetical order
   * xilinx_selectmap_probe(): remove unused resource *r variable
   * xilinx_selectmap_probe(): use a single gpio_desc* temporary
   * xilinx_selectmap_probe(): declare variables in reverse xmas tree

Changes since v4: (from Yilun and Krzysztof review)
 * xilinx-core: use sizeof() instead of hardcoded immediate
 * xilinx-core: fix module compilation (EXPORT_SYMBOL_GPL, MODULE_LICENSE,
   MODULE_AUTHOR, MODULE_DESCRIPTION)
 * xilinx-core: add private/public qualifiers for struct xilinx_fpga_core
 * xilinx-spi: remove struct xilinx_spi_conf. This struct isn't needed as
   the struct spi_device* can be retrieved from the struct device*.
 * dt-bindings: remove usage of "_b" and "-b" for the new driver. We
   agreed that the spi and selectmap driver will use different bindings
   which will be handled by the driver core and that the legacy names will
   be used only for the spi compatible.
 * xilinx-core: select between prog/init and prog_b/init-b

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 (4):
  fpga: xilinx-spi: extract a common driver core
  dt-bindings: fpga: xlnx,fpga-selectmap: add DT schema
  fpga: xilinx-selectmap: add new driver
  xilinx-core: add new gpio names for prog and init

 .../bindings/fpga/xlnx,fpga-selectmap.yaml    |  86 +++++++
 drivers/fpga/Kconfig                          |  12 +
 drivers/fpga/Makefile                         |   2 +
 drivers/fpga/xilinx-core.c                    | 229 ++++++++++++++++++
 drivers/fpga/xilinx-core.h                    |  27 +++
 drivers/fpga/xilinx-selectmap.c               |  95 ++++++++
 drivers/fpga/xilinx-spi.c                     | 224 ++---------------
 7 files changed, 466 insertions(+), 209 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

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2.43.0