[PATCH v3 0/2] spi: ma35d1-qspi: Add Nuvoton MA35D1 QSPI controller

[Chi-Wen Weng <cwweng.linux@gmail.com>]

From: Chi-Wen Weng <cwweng@nuvoton.com>

Add devicetree binding and SPI controller driver support for the
Nuvoton MA35D1 Quad SPI controller.

The MA35D1 QSPI controller supports SPI memory devices such as SPI NOR
and SPI NAND flashes in single, dual and quad I/O modes. This initial
driver implements a conservative PIO-based transfer path and spi-mem
operation support.

Changes in v3:
- Fixed DCO mismatch by using a consistent author and Signed-off-by
  address.
- Added spi_controller_mem_caps and set per_op_freq for spi-mem
  operations.
- Added SPI_CS_HIGH to controller mode_bits.
- Added a short delay after requesting FIFO reset before polling reset
  completion.
- Documented that the MA35D1 QSPI controller pushes one RX FIFO entry for
  each TX word in single, dual-output and quad-output modes, so TX-only
  transfers intentionally drain and discard RX data.
- Added missing linux/delay.h include for udelay().
- Cleaned up unused register bit definitions.

Changes in v2:
- Updated patch subject lines to match SPI subsystem style.
- Added commit message to the dt-bindings patch.
- Added ARCH_MA35 || COMPILE_TEST dependency to Kconfig.
- Expanded Kconfig help text.
- Converted the driver file header to // comments.
- Added reset control handling to the driver.
- Added resets property to the binding.
- Added num-cs constraint to the binding.
- Dropped the flash child node from the binding example.
- Used op->max_freq for spi-mem operations.
- Split low-level CS register handling from the SPI core .set_cs()
  callback.
- Handled SPI_CS_HIGH explicitly for the spi-mem direct CS path.
- Fixed spi-mem opcode transfer to use a u8 buffer.
- Limited spi-mem command opcode length to one byte.
- Forced spi-mem operations to 8-bit word size.
- Avoided driving bidirectional data pins during dummy cycles.
- Drained RX FIFO during TX-only transfers.
- Rejected invalid chip-select numbers instead of mapping them to SS1.
- Rejected unsupported dual/quad full-duplex generic SPI transfers.
- Fixed checkpatch style issues.

Chi-Wen Weng (2):
  dt-bindings: spi: nuvoton,ma35d1-qspi: Add Nuvoton MA35D1 QSPI
  spi: ma35d1-qspi: Add Nuvoton MA35D1 QSPI controller support

 .../bindings/spi/nuvoton,ma35d1-qspi.yaml     |  62 ++
 drivers/spi/Kconfig                           |  10 +
 drivers/spi/Makefile                          |   1 +
 drivers/spi/spi-ma35d1-qspi.c                 | 633 ++++++++++++++++++
 4 files changed, 706 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/nuvoton,ma35d1-qspi.yaml
 create mode 100644 drivers/spi/spi-ma35d1-qspi.c

-- 
2.25.1