The DMA controller can be used to transfer data to and from the SPI
controller without involving the CPU for each word of a SPI transfer.

Add support for DMA mode, and do some other cleanups while touching the
same code.

The dts changes in this series depend on the DMA series [1].

[1]: https://lore.kernel.org/lkml/20251201124911.572395-1-cosmin-gabriel.tanislav.xa@renesas.com/

Cosmin Tanislav (13):
  spi: rzv2h-rspi: fix rzv2h_rspi_transfer_one() indentation
  spi: rzv2h-rspi: remove call to spi_finalize_current_transfer()
  spi: rzv2h-rspi: do not set SPI_TRANS_FAIL_IO
  spi: rzv2h-rspi: use device-managed APIs
  spi: rzv2h-rspi: store RX interrupt in state
  spi: rzv2h-rspi: set MUST_RX/MUST_TX
  spi: rzv2h-rspi: set TX FIFO threshold to 0
  spi: rzv2h-rspi: enable TX buffer empty interrupt
  spi: rzv2h-rspi: split out PIO transfer
  dt-bindings: spi: renesas,rzv2h-rspi: document optional support for
    DMA
  spi: rzv2h-rspi: add support for DMA mode
  arm64: dts: renesas: r9a09g077: wire up DMA support for SPI
  arm64: dts: renesas: r9a09g087: wire up DMA support for SPI

 .../bindings/spi/renesas,rzv2h-rspi.yaml      |   8 +
 arch/arm64/boot/dts/renesas/r9a09g077.dtsi    |   8 +
 arch/arm64/boot/dts/renesas/r9a09g087.dtsi    |   8 +
 drivers/spi/spi-rzv2h-rspi.c                  | 281 ++++++++++++++----
 4 files changed, 242 insertions(+), 63 deletions(-)

-- 
2.52.0