em100: EM100-Pro command-line utility

This tool supports using the Dediprog EM100-Pro [1] in Linux. It supports both
the original version and the new -G2 variant.

The 'em100' device provides a way to emulate a SPI-flash chip. Various
connectors are available to allow it to take over from the in-circuit SPI chip
so that the SoC sees the em100's internal memory as the contents of the SPI
flash. Images can be loaded into the em100 over USB in a few seconds, thus
providing a much faster development cycle than is possible by reprogramming
the SPI flash each time.

Example:
  ./em100 --stop --set M25P80 -d file.bin --start -t -O 0xfff00000

Major features provided by the tool include:

- Set the chip being emulated (the tool supports about 600)
- Adjust the state of the hold pin, which supports overriding the internal SPI
- Use of several em100 devices, distinguished by their serial number
- Terminal mode, allowing the SoC to send messages
- Output a trace of SPI commands issued by the SoC
- Reading / writing em100 firmware (dangerous as it can brick your em100)

For help, use the -h option:

Usage:
  -c|--set CHIP:                  select chip emulation
  -d|--download FILE:             download FILE into EM100pro
  -u|--upload FILE:               upload from EM100pro into FILE
  -r|--start:                     em100 shall run
  -s|--stop:                      em100 shall stop
  -v|--verify:                    verify EM100 content matches the file
  -t|--trace:                     trace mode
  -O|--offset HEX_VAL:            address offset for trace mode
  -T|--terminal:                  terminal mode
  -F|--firmware-update FILE:      update EM100pro firmware (dangerous)
  -f|--firmware-dump FILE:        export raw EM100pro firmware to file
  -g|--firmware-write FILE:       export EM100pro firmware to DPFW file
  -S|--set-serialno NUM:          set serial number to NUM
  -p|--holdpin [LOW|FLOAT|INPUT]: set the hold pin state
  -x|--device BUS:DEV             use EM100pro on USB bus/device
  -x|--device DPxxxxxx            use EM100pro with serial no DPxxxxxx
  -l|--list-devices               list all connected EM100pro devices
  -D|--debug:                     print debug information.
  -h|--help:                      this help text


[1] https://www.dediprog.com/product/EM100Pro-G2