Unless you are using the classic Mohor debug interface, you should now use the upstream version of OpenOCD

OpenOCD

openOCD including OpenRISC support with Mohor debug interface and Nathan Yawn adv_dbg_if debug interface.

A JTAG driver acting as a client for a VPI JTAG server interface is also included.

+---------------     +----------------+      +----------------+      +------------------+      +----------+ 
+              +     +                +      +                +      +                  +      +          + 
+ OpenOCD core + --> + JAG VIP driver + <==> + JAG VIP server + <--> + JTAG VPI verilog + <--> + JTAG TAP + 
+              +     +                +      +                +      +                  +      +          + 
+---------------     +----------------+      +----------------+      +------------------+      +----------+
                         jtag_vpi.c              jtag_vpi.c               jtag_vpi.v             any tap...
--------------------------------------- TCP  ------------------  VPI --------------------------------------
---------------------------------------      --------------------------------------------------------------
              OpenOCD                                                VPI + Verilog RTL

If you want to use the VPI JTAG driver, you need to configure OpenOCD like this:

./configure --enable-jtag_vpi --enable-adv_debug_sys --enable-maintainer-mode

Then you can start OpenOCD:

./src/openocd -f jtag_vpi.tcl

The JTAG VPI server (on the simulation side) has to be started before OpenOCD.