[U-Boot] [U-BOOT PATCH 0/3] add support for spi-nor device on HiFive Unleashed board

[Sagar Shrikant Kadam]

This patch series adds support for 32MiB SPI-NOR flash (is25wp256 from
ISSI). Many thanks to Bhargav Shah <bhargavshah1988 at gmail.com> for 
porting the spi-nor patches from linux to U-boot in order to support
this device.
Ref: linux patches which are under review
https://lkml.org/lkml/2019/7/2/859

Linux has an option of registering post-bfpt fixups in order to over-ride
the incorrect configuration of flash devices due to wrong SFDP entries read
from the flash device during nor scan phase. The 1st patch introduces this
support to register post bfpt fixup hook similar to that done in linux.

The second patch in the series enables support for the flash device in
single I/O mode. A post bfpt fixup is registered because 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.
The SPI_NOR_HAS_BP3 bit indicates that the flash protection block has BP0
to BP3 bits.

Lock/Unlock mechanism:
The implementation is based on stm_lock/unlock scheme and is validated for
different number of blocks passed to sf command. Unlock scheme unilateraly
clears all the protection bits of all blocks in the status register.

The series is based on the master branch of[1]
[1] https://gitlab.denx.de/u-boot/custodians/u-boot-riscv

and is available in dev/sagark/hifive-spi-nor_v2 branch of[2]
[2] https://github.com/sagsifive/u-boot.

Flash operations like erase/read/write lock/unlock are verified and
data integrity is checked using sf commands as follows:

=> sf write 0x80600000 0x0 0x2000000
device 0 whole chip
SF: 33554432 bytes @ 0x0 Written: OK
=> sf read 0x82700000 0x0 0x2000000
device 0 whole chip
SF: 33554432 bytes @ 0x0 Read: OK
=> cmp.b 0x80600000 0x82700000 0x2000000
Total of 33554432 byte(s) were the same

=> sf protect lock 0x1000000 0x1000000
=> mw 0x80600000 0x12345678 0x2000000
=> sf write 0x80600000 0x0 0x2000000
   Reset the board to flush out data from memory
=> sf probe
=> sf read 0x80600000 0x0 0x2000000
   In memory dump after sf read from address 0x80600000 we can see that
   upper 16MiB flash section is protected.


Sagar Shrikant Kadam (3):
  spi: nor: add spi-nor-fixup handlers for nor devices
  spi: nor: add support for is25wp256
  spi: riscv: use single bit mode for spi transfers

 board/sifive/fu540/Kconfig     |   5 +
 drivers/mtd/spi/sf_internal.h  |  23 +++
 drivers/mtd/spi/spi-nor-core.c | 373 +++++++++++++++++++++++++++++++++++------
 drivers/mtd/spi/spi-nor-ids.c  |   5 +
 drivers/spi/spi-sifive.c       |   7 +-
 include/linux/mtd/spi-nor.h    |   8 +
 6 files changed, 363 insertions(+), 58 deletions(-)

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2.7.4