[PATCH v9 0/2] mtd: spi-nor: add support for is25wp256 spi-nor flash

[Sagar Shrikant Kadam]

The patch series adds basic support for 32MiB spi-nor is25wp256 present on HiFive
Unleashed A00 board. The flash device gets BFPT_DWORD1_ADDRESS_BYTES_3_ONLY
from BFPT table for address width, whereas the flash can support 4 byte
address width, so the address width is configured by using the post bfpt
fixup hook as done for is25lp256 device in
commit cf580a924005 ("mtd: spi-nor: fix nor->addr_width when its value
configured from SFDP does not match the actual width")

Patches are based on original work done by Wesley Terpstra and/or
Palmer Dabbelt:
https://github.com/riscv/riscv-linux/commit/c94e267766d62bc9a669611c3d0c8ed5ea26569b

Erase/Read/Write operations are verified on HiFive Unleashed board using  mtd and
flash utils (v1.5.2):
1. mtd_debug  	: Options available are : erase/read/write.
2. flashcp	: Single utility that erases flash, writes a file to flash and verifies the data back.

The changes are available under branch dev/sagark/spi-nor-v9 at
https://github.com/sagsifive/riscv-linux-hifive 

Revision history:
V8<->V9:
-Rebased this series to mainline v5.3-rc8
-Corrected number of sectors in the spi nor id table for is25wp256 device as suggested in the review.
-The lock/unlock scheme in the V8 version of this series needs to have a more generic approach.
 These protection scheme patches are not included in this series, will submit those separately.

V7<->V8:
-Rebased this series on mainline v5.3-rc4.
-Removed remaining func_reg reference from issi_lock as updating OTP region was dropped as part of V6.
-Updated Reviewed-By tags to 1st and 2nd patch.

V6<->V7:
-Incorporated review comments from Vignesh.
-Used post bfpt fixup hook as suggested by Vignesh.
-Introduce SPI_NOR_HAS_BP3 to identify whether the flash has 4th bit protect bit.
-Prefix generic flash access functions with spi_nor_xxxx.

V5<->V6:
-Incorporated review comments from Vignesh.
-Set addr width based on device size and if SPI_NOR_4B_OPCODES is set.
-Added 4th block protect identifier (SPI_NOR_HAS_BP3) to flash_info structure 
-Changed flash_info: flag from u16 to u32 to accommodate SPI_NOR_HAS_BP3
-Prefix newly added function with spi_nor_xxx.
-Dropped write_fr function, as updating OTP bit's present in function register doesn't seem to be a good idea.
-Set lock/unlock schemes based on whether the ISSI device has locking support and  BP3 bit present.

V4<->V5:
-Rebased to linux version v5.2-rc1.
-Updated heading of this cover letter with sub-system, instead of just plain "add support for is25wp256..."

V3<->V4:
-Extracted comman code and renamed few stm functions so that it can be reused for issi lock implementation.
-Added function's to read and write FR register, for selecting Top/Bottom area.

V2<->V3:
-Rebased patch to mainline v5.1 from earlier v5.1-rc5.
-Updated commit messages, and cover letter with reference to git URL and author information.
-Deferred flash_lock mechanism and can go as separate patch. 

V1<-> V2:
-Incorporated changes suggested by reviewers regarding patch/cover letter versioning, references of patch.
-Updated cover letter with description for flash operations verified with these changes.
-Add support for unlocking is25xxxxxx device.
-Add support for locking is25xxxxxx device.

v1:
-Add support for is25wp256 device.

Sagar Shrikant Kadam (2):
  mtd: spi-nor: add support for is25wp256
  mtd: spi-nor: fix nor->addr_width for is25wp256

 drivers/mtd/spi-nor/spi-nor.c | 9 ++++++++-
 include/linux/mtd/spi-nor.h   | 1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

-- 
1.9.1