feature request: console uart redirect

[tomsteininger]

In bench development and characterization, there is a consistent requirement to redirect the console UART to the physical pins in order to use an external usb-uart interface. This is has been accomplished so far by this:

enable console redirect

pfexec humility -t <target> hiffy -c FmcDemo.poke32 -a addr=0x60000700,value=0x1

disable console redirect

pfexec humility -t <target> hiffy -c FmcDemo.poke32 -a addr=0x60000700,value=0x0

The FPGA map recently changed, which then requires update of mfg and test scripts which make use of this.

It would be better to have a hubris feature that does this so the scripts and user don't need to keep track of the address map.

i.e., in the latest FPGA, it appears at :
pfexec humility -t <target> hiffy -c FmcDemo.poke32 -a addr=0xC0000600,value=0x1