Here is a link to a program called PiTone which can be used to create a CTCSS tone.? PiTone runs on a Raspberry Pi (can be the same one that is running Allstar).? It uses a D/A converter connected to the I2C bus to create a stepped sinewave which is easy to filter to a "pure" sinwave.
We have used it on our local repeaters (DR-1X and Micor) for more than 4 years.
Steve - N8AR