[PATCH v2 0/2] add support for Cadence's XSPI controller

[Parshuram Thombare]

This patch series adds support for Cadence's XSPI controller.
This controller supports multiple work modes e.g.
STIG (Software Triggered Instruction Generator) mode, ACMD PIO
and CDMA modes, direct mode.
In STIG mode, controller sends low-level instructions to memory.
Each instruction is 128-bit width. There is special instruction
DataSequence which carries information about data phase.
Driver uses Slave DMA interface to transfer data as only this
interface can be used in STIG work mode.
The CDMA work mode is dedicated for high-performance application
where very low software overhead is required. In this mode the
Command Engine is programmed by the series of linked descriptors
stored in system memory. These descriptors provide commands to execute
and store status information for finished commands.
The PIO mode work mode is dedicated for single operation where
constructing a linked list of descriptors would require too
much effort.
Currently ACMD PIO mode is used for NOR flash read, program, erase
operations, all other operations are handled in STIG work mode.

Changes since v1:
1. Use ACMD PIO work mode for NOR read, program and erase operations,
   for everything else use STIG(Software Triggered Instruction
   Generator) work mode.
2. Changes suggested by Lukas.

Parshuram Thombare (2):
  spi: cadence: add dt-bindings documentation for Cadence XSPI
    controller
  spi: cadence: add support for Cadence XSPI controller

 .../devicetree/bindings/spi/cdns,xspi.yaml         |  169 +++
 drivers/spi/Kconfig                                |   11 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-cadence-xspi.c                     | 1102 ++++++++++++++++++++
 4 files changed, 1283 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/cdns,xspi.yaml
 create mode 100644 drivers/spi/spi-cadence-xspi.c

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2.7.4