[PATCH v4 0/4] spi: sophgo: Add SPI NOR controller for SG2042

[Zixian Zeng]

Add support SPI NOR flash memory controller for SG2042, using upstreamed
SG2044 SPI NOR driver.

Tested on SG2042 Pioneer Box, read, write operations.
Thanks Chen Wang who provided machine and guidance.

Signed-off-by: Zixian Zeng <sycamoremoon376 at gmail.com>
---
Changes in v4:
- patch1: Explain why SG2042 is not compatible with SG2044 and add Fixes tag.
- patch2: Explain the hardware differences between SG2042 and SG2044.
- patch4: Remove the extra "sophgo,sg2044-spifmc-nor" compatible property.
- Link to v3: https://lore.kernel.org/r/20250629-sfg-spifmc-v3-0-28db1f27e999@gmail.com

Changes in v3:
- Drop the patch which adds additional flash_info into gigadevice.c
- patch1: Because of the incompatibility, separate the SG2042 from the previous fallback mechanism to independent one.
- patch2: Newly add configurable options to spi-sg2044-nor driver.
- patch3: Fix reading bytes issue that causes the spi_nor_check_sfdp_signature() failure on SG2042.
- Link to v2: https://lore.kernel.org/r/20250525-sfg-spifmc-v2-0-a3732b6f5ab4@gmail.com

Changes in v2:
- patch1: Accept devicetree nodes whose compatible contains only
  "sophgo,sg2044-spifmc-nor" to avoid breaking existing devicetrees.
- patch1: Improve the commit subject message.
- patch2: Dump the SFDP information to commit message.
- Link to v1: https://lore.kernel.org/r/20250523-sfg-spifmc-v1-0-4cf16cf3fd2a@gmail.com

---
Zixian Zeng (4):
      spi: dt-bindings: spi-sg2044-nor: Change SOPHGO SG2042
      spi: spi-sg2044-nor: Add configurable chip_info
      spi: spi-sg2044-nor: Add SPI-NOR controller for SG2042
      riscv: dts: sophgo: Add SPI NOR node for SG2042

 .../devicetree/bindings/spi/spi-sg2044-nor.yaml    |  9 +++----
 .../riscv/boot/dts/sophgo/sg2042-milkv-pioneer.dts | 24 ++++++++++++++++++
 arch/riscv/boot/dts/sophgo/sg2042.dtsi             | 24 ++++++++++++++++++
 drivers/spi/spi-sg2044-nor.c                       | 29 +++++++++++++++++++---
 4 files changed, 77 insertions(+), 9 deletions(-)
---
base-commit: 8727665368cd4af112146b650ec0ebac038b5cf5
change-id: 20250523-sfg-spifmc-7a910290e964

Best regards,
-- 
Zixian Zeng <sycamoremoon376 at gmail.com>