[PATCH v5 0/6] mtd: spi-nor: Quad Enable and (un)lock methods

[<Tudor.Ambarus@microchip.com>]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

Tested on w25q128jvq.

Fixed the clearing of QE bit on (un)lock() operations. Reworked the
Quad Enable methods and the disabling of the block write protection
at power-up.

v5:
- Rename all Quad Enable methods in one patch
- Extend the Read Back test to both SR1 and SR2 in one patch
- Reorder patches, so that the fixes come one after another
- Collect R-b tags.

v4:
- Use dev_dbg insted of dev_err for low level info
- replace "&nor->bouncebuf[0]" with "nor->bouncebuf" and "&sr_cr[0]" with
  "sr_cr". Update across all patches.

v3: split patches, update retlen handling in sst_write.

v2:
- Introduce spi_nor_write_16bit_cr_and_check() as per Vignesh's suggestion. The
  Configuration Register contains bits that can be updated in future: FREEZE,
  CMP. Provide a generic method that allows updating all bits of the
  Configuration Register.
- Fix SNOR_F_NO_READ_CR case in
  "mtd: spi-nor: Rework the disabling of block write protection". When the flash
  doesn't support the CR Read command, we make an assumption about the value of
  the QE bit. In spi_nor_init(), call spi_nor_quad_enable() first, then
  spi_nor_unlock_all(), so that at the spi_nor_unlock_all() time we can be sure
  the QE bit has value one, because of the previous call to spi_nor_quad_enable().
- Fix if statement in spi_nor_write_sr_and_check():
  if (nor->flags & SNOR_F_HAS_16BIT_SR)
- Fix documentation warnings.
- New patch: "mtd: spi-nor: Check all the bits written, not just the BP ones".
- Drop Global Unlock patches, will send them in a different patch set.

The patch set can be tested using mtd-utils:
1/ do a read-erase-write-read-back test immediately after boot, to check
the spi_nor_unlock_all() method. The focus is on the erase/write
methods, we want to see if the flash is unlocked at power-up.
        mtd_debug read /dev/mtd-yours offset size read-file
        hexdump read-file
        mtd_debug erase /dev/mtd-yours offset size
        dd if=/dev/urandom of=write-file bs=please-choose count=please-choose
        mtd_debug write /dev/mtd-yours offset write-file-size write-file
        mtd_debug read /dev/mtd-yours offset write-file-size read-file
        sha1sum read-file write-file
2/ lock flash then try to erase/write it, to see if the lock works
        flash_lock /dev/mtd-yours offset block-count
        Do the read-erase-write-read-back test from 1/. The contents of
        flash should not change in the erase and write steps.
3/ unlock flash and do the read-erase-write-read-back from 1/. The value of the
   QEE should not change and you should be able to erase and write the flash.
   Test 1/ should be successful.

Tudor Ambarus (6):
  mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()
  mtd: spi-nor: Rework the disabling of block write protection
  mtd: spi-nor: Extend the SR Read Back test
  mtd: spi-nor: Rename CR_QUAD_EN_SPAN to SR2_QUAD_EN_BIT1
  mtd: spi-nor: Merge spansion Quad Enable methods
  mtd: spi-nor: Rename Quad Enable methods

 drivers/mtd/spi-nor/spi-nor.c | 438 ++++++++++++++++++++++++------------------
 include/linux/mtd/spi-nor.h   |  12 +-
 2 files changed, 254 insertions(+), 196 deletions(-)

-- 
2.9.5