http://www.freescale.com/webapp/sps/site/application.jsp?code=APLIEEE_1588
The MCP5125 isn't listed on the above page.
"Freescale began shipping processors with hardware timestamp capabilities in 2007."
The MCP2515 is in the right time frame, but doesn't seem to have hardware support for IEEE 1558.
It depends on how accurate you need the timestamp. If you don't need the accuracy of the hardware timestamping then software timestamps might be an option.
Tom
