[Libre-soc-dev] Programming a PPC440EPx via JTAG
cestrauss at gmail.com
Tue Oct 12 13:56:40 BST 2021
I think you wanted to hear about how an embedded PowerPC CPU, which I
have in the Lab, can be programmed/debugged via JTAG.
The board is this one:
It seems to have a PPC440EPx, a PowerPC embedded SoC.
The JTAG protocol, apparently undocumented and proprietary, was
reverse-engineered, and seems to have:
1) a command for uploading and executing a single Power instruction,
2) a debug SPR that can be read and written into,
3) a debug mode register, for doing reset, halt, run, etc.
From that, higher-level operations can be performed, like reading and
writing to registers, SPRs, memory, PC, etc.
Here's the program which implements the above, reading a high-level
command file, and generating an SVF file:
A sample command file is this:
It loads a program into memory, which implements a XMODEM protocol
server over the serial port, and writes the incoming file (something
like uBoot.bin or memtest.bin) into Flash.
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