What is the maximum frequency the JTAG interface can be run at in a CoolRunner-II or a CoolRunner XPLA3?
This information is provided in the BSDL file under the TAP_SCAN_CLOCK attribute.
For the CoolRunner-II, it is 33 MHz.
For the CoolRunner XPLA3, it is 10 MHz.
JTAG TAP Timing Parameters for CoolRunner-II