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| author | Miquel Raynal <miquel.raynal@bootlin.com> | 2026-05-26 16:56:46 +0200 |
|---|---|---|
| committer | Pratyush Yadav <pratyush@kernel.org> | 2026-05-27 14:36:02 +0200 |
| commit | f5d81415a7e12cc73b510bfac181411fedfe6345 (patch) | |
| tree | c3cba2438cdd0d533f17dc1ae6c417c424012acb /Documentation/driver-api | |
| parent | e3fb31d8847fef2ce37c5f60bc77d3f731a2419b (diff) | |
| download | linux-next-f5d81415a7e12cc73b510bfac181411fedfe6345.tar.gz linux-next-f5d81415a7e12cc73b510bfac181411fedfe6345.zip | |
mtd: spi-nor: Add steps for testing locking with CMP
Extend the test coverage by giving guidelines to verify the CMP bit acts
according to our expectations.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Pratyush Yadav <pratyush@kernel.org>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/mtd/spi-nor.rst | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/driver-api/mtd/spi-nor.rst b/Documentation/driver-api/mtd/spi-nor.rst index f817a9193731..747a326fb6c0 100644 --- a/Documentation/driver-api/mtd/spi-nor.rst +++ b/Documentation/driver-api/mtd/spi-nor.rst @@ -336,3 +336,40 @@ section, after the ``---`` marker. ------------------+----------+--------- 00000000-0000ffff | locked | 1 00010000-03ffffff | unlocked | 1023 + + If the flash features a Complement (CMP) bit, we can protect with + more granularity above half of the capacity. Let's lock all but one + block, then unlock one more block:: + + root@1:~# all_but_one=$((($size / $bs) - ($ss / $bs))) + + root@1:~# flash_lock -u /dev/mtd0 + root@1:~# flash_lock -l /dev/mtd0 $ss $all_but_one # all but the first + root@1:~# show_sectors + software locked sectors + region (in hex) | status | #sectors + ------------------+----------+--------- + 00000000-0000ffff | unlocked | 1 + 00010000-03ffffff | locked | 1023 + root@1:~# flash_lock -u /dev/mtd0 $ss $(($ss / $bs)) # all but the two first + root@1:~# show_sectors + software locked sectors + region (in hex) | status | #sectors + ------------------+----------+--------- + 00000000-0001ffff | unlocked | 2 + 00020000-03ffffff | locked | 1022 + root@1:~# flash_lock -u /dev/mtd0 + root@1:~# flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side + root@1:~# show_sectors + software locked sectors + region (in hex) | status | #sectors + ------------------+----------+--------- + 00000000-03feffff | locked | 1023 + 03ff0000-03ffffff | unlocked | 1 + root@1:~# flash_lock -u /dev/mtd0 $(($size - (2 * $ss))) $(($ss / $bs)) # all but two + root@1:~# show_sectors + software locked sectors + region (in hex) | status | #sectors + ------------------+----------+--------- + 00000000-03fdffff | locked | 1022 + 03fe0000-03ffffff | unlocked | 2 |