Content originally posted in LPCWare by starblue on Thu Feb 20 02:06:51 MST 2014
It seems the LPC-Link2 debugger does exactly that, in the schematics all the JTAG pins are connected to SGPIO. It's also quite fast, faster than a Ulink2.
From my personal experience with SGPIO I also think it is possible. 10 MHz JTAG clock should be doable under processor control, more if you can get DMA to work, which however seems tricky (I haven't done it).