jafari@raspberrypi:~ $ sudo flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=24000 -w backup.rom 
flashrom v1.5.0-devel (git:v1.4.0-68-g339a7dcd) on Linux 6.1.21-v8+ (aarch64)
flashrom is free software, get the source code at https://flashrom.org

Found XMC flash chip "XM25QU256C/XM25QU256D" (32768 kB, SPI) on linux_spi.
===
This flash part has status UNTESTED for operations: WP
The test status of this chip may have been updated in the latest development
version of flashrom. If you are running the latest development version,
please email a report to flashrom@flashrom.org if any of the above operations
work correctly for you with this flash chip. Please include the flashrom log
file for all operations you tested (see the man page for details), and mention
which mainboard or programmer you tested in the subject line.
You can also try to follow the instructions here:
https://www.flashrom.org/contrib_howtos/how_to_mark_chip_tested.html
Thanks for your help!
Reading old flash chip contents... done.
FAILED at 0x00008000! Expected=0xff, Found=0x00, failed byte count from 0x00008000-0x00008fff: 0x1000
Erase/write done from 0 to 1ffffff
Write Failed!Uh oh. Erase/write failed. Checking if anything has changed.
Reading current flash chip contents... done.
Apparently at least some data has changed.
Your flash chip is in an unknown state.
Please report this to the mailing list at flashrom@flashrom.org or
on IRC (see https://www.flashrom.org/Contact for details), thanks!