spi: support the SpacemiT K1 SPI controller

This series adds support for the SPI controller found in the SpacemiT
K1 SoC.  The driver currently supports only master mode.  The controller
has two 32-entry FIFOs and supports PIO and DMA for transfers.

Version 5 adds Yixun's Reviewed-by tag on patch 3, and is based on
Linux v6.18-rc1.

                                        -Alex

This series is available here:
  https://github.com/riscstar/linux/tree/outgoing/spi-v5

Between version 4 and version 5:
  - Added Yixun's Reviewed-by tag on patch 3

Here is version 4 of this series:
  https://lore.kernel.org/lkml/20250925121714.2514932-1-eld...

Between version 3 and version 4 (all suggested by Yixun):
  - Fixed an underrun/overrun comment error
  - Renamed a pinctrl node
  - Formatted dmas and dma-names properties on one line

Here is version 3 of this series:
  https://lore.kernel.org/lkml/20250922161717.1590690-1-eld...

Between version 2 and version 3:
  - Add Conor's Acked-by to patch 1
  - Add Rob's Reviewed-by to patch 1
  - Added imply_PDMA to the SPI_SPACEMIT_K1 Kconfig option
  - Fixed a bug pointed out by Vivian (and Troy) in word-sized reads
  - Added a comment stating we use 1, 2, or 4 bytes per word
  - Cleaned up DMA channels properly in case of failure setting up
  - No longer use devm_*() for allocating DMA channels or buffer
  - Moved the SPI controller into the dma-bus memory region

Here is version 2 of this series:
  https://lore.kernel.org/lkml/20250919155914.935608-1-elde...

Between version 1 and version 2:
  - Use enum rather than const for the binding compatible string
  - Omit the label and status property in the binding example
  - The spi-spacemit-k1.o make target is now added in sorted order
  - The SPI_SPACEMIT_K1 config option is added in sorted order
  - The SPI_SPACEMIT_K1 config does *not* depend on MMP_PDMA,
    however MMP_PDMA is checked at runtime, and if not enabled,
    DMA will not be used
  - Read/modify/writes of registers no longer use an additional
    "virt" variable to hold the address accessed
  - The k1_spi_driver_data->ioaddr field has been renamed base
  - The DMA address for the base address is maintained, rather than
    saving the DMA address of the data register
  - The spi-max-frequency property value is now bounds checked
  - A local variable is now initialized to 0 in k1_spi_write_word()
  - The driver name is now "k1-spi"
  - DT aliases are used rather than spacemit,k1-ssp-id for bus number
  - The order of two pin control properties was changed as requested
  - Clock names and DMA names are now on one line in the "k1.dtsi"
  - The interrupts property is used rather than interrupts-extended
  - The order of two pin control properties was changed as requested
  - Clock names and DMA names are now on one line in the "k1.dtsi"
  - The interrupts property is used rather than interrupts-extended

Here is version 1 of this series:
  https://lore.kernel.org/lkml/20250917220724.288127-1-elde...


Alex Elder (3):
  dt-bindings: spi: add SpacemiT K1 SPI support
  spi: spacemit: introduce SpacemiT K1 SPI controller driver
  riscv: dts: spacemit: define a SPI controller node

 .../bindings/spi/spacemit,k1-spi.yaml         |  84 ++
 .../boot/dts/spacemit/k1-bananapi-f3.dts      |   7 +
 arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi  |  20 +
 arch/riscv/boot/dts/spacemit/k1.dtsi          |  15 +
 drivers/spi/Kconfig                           |   9 +
 drivers/spi/Makefile                          |   1 +
 drivers/spi/spi-spacemit-k1.c                 | 965 ++++++++++++++++++
 7 files changed, 1101 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spacemit,k1-spi.yaml
 create mode 100644 drivers/spi/spi-spacemit-k1.c


base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
-- 
2.48.1