tp_smapi works with the x200.
The problem is that the ACPI BIOS registers an IO Port reservation for the ports tp_smapi(or specifically thinkpad_ec) need.
Once you patch the DSDT table(or Lenovo releases a new BIOS fixing the port reservation) it works like a charm.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
tp_smapi works with the x200.
The problem is that the ACPI BIOS registers an IO Port reservation for the ports tp_smapi(or specifically thinkpad_ec) need.
Once you patch the DSDT table(or Lenovo releases a new BIOS fixing the port reservation) it works like a charm.