Add support for Loongson-1 NAND

Add the driver and dt-binding document for Loongson-1 NAND.

Changes in v9:
- Change the compatible to 'loongson,ls1*-nand-controller'.
- Rename the dt-binding file to loongson,ls1b-nand-controller.yaml.
- Update MAINTAINERS file accordingly.
- Some minor adjustments.
- Rebasing due to recent upstream changes.
- Link to v8: https://lore.kernel.org/r/20240808-loongson1-nand-v8-0-c9...

Changes in v8:
- Add a description part.
- Adjust the compatible because the match data for ls1c-nfc differs from ls1b-nfc.
- Mark 'nand-use-soft-ecc-engine' and 'nand-ecc-algo' as mandatory.
- Delete the superfluous blank lines.
- Drop NAND_MONOLITHIC_READ and add support for real subpage read instead.
- Simplify the logic of ls1b_nand_parse_address() and ls1c_nand_parse_address().
- Split ls1x_nand_set_controller() into ls1x_nand_parse_instructions()
  and ls1x_nand_trigger_op().
- Implement ls1x_nand_op_cmd_mapping() to convert the opcodes instead of forcing them.
- Add ls1x_nand_check_op().
- Remove struct ls1x_nand after moving its members to struct ls1x_nfc.
- Add the prefix 'LS1X_' for all registers and their bits.
- Drop the macros: nand_readl() and nand_writel().
- Some minor fixes and improvements.
- Link to v7: https://lore.kernel.org/r/20240430-loongson1-nand-v7-0-60...

Changes in v7:
- Rename the file to loongson,ls1b-nfc.yaml
- Rename the Kconfig dependency to LOONGSON1_APB_DMA
- Link to v6: https://lore.kernel.org/r/20240327-loongson1-nand-v6-0-7f...

Changes in v6:
- Amend Kconfig
- Add the dt-binding document
- Modify nand_read_subpage() to allow subpage read by a single operation
- Add DT support for driver
- Use DT data instead of platform data
- Remove MAX_ID_SIZE
- Remove case NAND_OP_CMD_INSTR in ls1x_nand_set_controller()
- Move ECC configuration to ls1x_nand_attach_chip()
- Rename variable "nand" to "ls1x"
- Rename variable "nc" to "nfc"
- Some minor fixes
- Link to v5: https://lore.kernel.org/all/20210520224213.7907-1-keguang...

Changes in v5:
- Update the driver to fit the raw NAND framework.
- Implement exec_op() instead of legacy cmdfunc().
- Use dma_request_chan() instead of dma_request_channel().
- Some minor fixes and cleanups.

Changes in v4:
- Retrieve the controller from nand_hw_control.

Changes in v3:
- Replace __raw_readl/__raw_writel with readl/writel.
- Split ls1x_nand into two structures:
ls1x_nand_chip and ls1x_nand_controller.

Changes in v2:
- Modify the dependency in Kconfig due to the changes of DMA module.

Signed-off-by: Keguang Zhang <keguang.zhang@gmail.com>
---
Keguang Zhang (2):
      dt-bindings: mtd: Add Loongson-1 NAND Controller
      mtd: rawnand: Add Loongson-1 NAND Controller Driver

 .../mtd/loongson,ls1b-nand-controller.yaml         |  75 ++
 MAINTAINERS                                        |   1 +
 drivers/mtd/nand/raw/Kconfig                       |   7 +
 drivers/mtd/nand/raw/Makefile                      |   1 +
 drivers/mtd/nand/raw/loongson1_nand.c              | 824 +++++++++++++++++++++
 5 files changed, 908 insertions(+)
---
base-commit: 62f92d634458a1e308bb699986b9147a6d670457
change-id: 20240316-loongson1-nand-98327d77e0f6

Best regards,
-- 
Keguang Zhang <keguang.zhang@gmail.com>