serial: 8250: handle ixp4xx register endianness correctly

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Unlike modern SoCs that just work in both big-endian and little-endian
mode using the readl()/writel() or readb()/writeb() accessors, the
internal registers on ixp4xx behave like native-endian 32-bit registers
in both modes, which requires adjusting the register address
when using 8-bit access.

The existing dts files are written for big-endian kernels and 8-bit
access, which does not work with little-endian kernels.

Add a quirk that makes the 8250 OF driver:

1. Mask off any hardcoded offset.
2. Add the += 3 offset if and only if we are running on big endian.

This should work in all combinations of big-endian and little-endian
kernels with either variant of the DTS file.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[linusw@kernel.org: Modified to just play with the offset]
Signed-off-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260709-ixp4xx-serial-hackfix-v2-1-465fc8e4c54c@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Arnd Bergmann 2026-07-09 21:21:08 +02:00 • committed by Greg Kroah-Hartman

parent 7ea38c49e7

commit a76c010ec3

2 changed files with 30 additions and 1 deletions

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19

drivers/tty/serial/8250/8250_early.c

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12

drivers/tty/serial/8250/8250_of.c

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