HyperFlash devices in Renesas SoCs use 2-bytes addressing, according
to HW manual paragraph 62.3.3 (which officially describes Serial Flash
access, but seems to be applicable to HyperFlash too). And 1-byte bus
read operations to 2-bytes unaligned addresses in external address space
read mode work incorrectly (returns the other byte from the same word).
Function memcpy_fromio(), used by the driver to read data from the bus,
in ARM64 architecture (to which Renesas cores belong) uses 8-bytes
bus accesses for appropriate aligned addresses, and 1-bytes accesses
for other addresses. This results in incorrect data read from HyperFlash
in unaligned cases.
This issue can be reproduced using something like the following commands
(where mtd1 is a parition on Hyperflash storage, defined properly
in a device tree):
[Correct fragment, read from Hyperflash]
root@rcar-gen3:~# dd if=/dev/mtd1 of=/tmp/zz bs=32 count=1
root@rcar-gen3:~# hexdump -C /tmp/zz
00000000 f4 03 00 aa f5 03 01 aa f6 03 02 aa f7 03 03 aa |................|
00000010 00 00 80 d2 40 20 18 d5 00 06 81 d2 a0 18 a6 f2 |....@ ..........|
00000020
[Incorrect read of the same fragment: see the difference at offsets 8-11]
root@rcar-gen3:~# dd if=/dev/mtd1 of=/tmp/zz bs=12 count=1
root@rcar-gen3:~# hexdump -C /tmp/zz
00000000 f4 03 00 aa f5 03 01 aa 03 03 aa aa |............|
0000000c
Fix this issue by creating a local replacement of the copying function,
that performs only properly aligned bus accesses, and is used for reading
from HyperFlash.
Fixes: ca7d8b980b ("memory: add Renesas RPC-IF driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Link: https://lore.kernel.org/r/20210922184830.29147-1-andrew_gabbasov@mentor.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
1869023e24