CONFIG_M523x is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k
MCF523x
modulename: m523x.ko
configname: CONFIG_M523x
Linux Kernel Configuration
└─>MCF523x
In linux kernel since version 2.6.14 (release Date: 2005-10-27)
Freescale Coldfire 5230/1/2/4/5 processor support