analogue input

[Corto]

I would like to be able to read an analogue input with my olinuxino, the first thing I thought has been to use an external ADC (there are a lot of modules using I2C or SPI to communicate with the board) but for my purposes I don't need to respect hard constraints on sampling frequency (I just would read a DC signal at the moment) so what I thought is: can I use the line-in provided on the board?
Also i see from the datasheet that on the GPIO there are 4 pin connected to the processor pins TPX and TPY (respective the 37,38,39 and 40 ones) which corresponds with TP ADC inputs...

Does anyone know what are these TP ADC and if I can use them or the line-in to acquire an analogue signal?