Physical debug interface - two wire?

Does SiFive have a two wire debug interface (e.g. like SWD on ARM) for the RISC-V, rather than the full JTAG? I am working on an application that is very I/O constrained.

I also find this JTAG connection, from their debug spc I find:
DTMs are specified for protocols like USB, I2C, SPI, and SWD.
but indeed i donot find any description from their E3/5 series SPC