A13-OLinuXino

Said to be like the Raspberry Pi but faster and completely open source.

https://www.olimex.com/Products/OLinuXino/A13/A13-OLinuXino/

https://www.pcworld.com/article/2013622/tiny-57-pc-is-like-the-raspberry-pi-but-faster-and-fully-open.html

My understanding is that the available documentation on the Allwinner chips is essentially useless.

My understanding is that the available documentation on the Allwinner chips is essentially useless.

I just took a look at the linked documents and the content of the guide is little above a fag packet description, but not much.
The wiki is probably less than a fag packet.

The sunxi hacking wiki links to a 409-page manual in addition to the lesser datasheet. (Former also copied at Free Electrons.)

(cf. QuanZhi A10)