I did some research and noticed that this only seems to happen on the Nexus 4. On the Nexus 5 (Android 4.4.4), reading the same sysfs file actually yields a result:
shell@hammerhead:/ $ cat /sys/devices/system/cpaccess/cpaccess0/cp_rw 512f06f0
I did some research and noticed that this only seems to happen on the Nexus 4. On the Nexus 5 (Android 4.4.4), reading the same sysfs file actually yields a result:
shell@hammerhead:/ $ cat /sys/devices/ system/ cpaccess/ cpaccess0/ cp_rw
512f06f0