Given http://espressobin.net/mainline-linux/ I assumed that mainline would have been a little more out-of-the-box…
My stab at an updated device tree is here: https://github.com/bstreiff/linux/commit/87939cc90aa9d63c26eab67cade2cd5f0ac2a149
(this is mostly transplanted out of Marvell’s tree: https://github.com/MarvellEmbeddedProcessors/linux-marvell/blob/linux-4.4.52-armada-17.06/arch/arm64/boot/dts/marvell/armada-3720-community.dts )
This adds support for sdhci1 and the SPI flash (note: the partition layout is probably not completely correct). I’m missing the definition for the regulator to switch between a 3.3V and 1.8V SD card I/O voltage, but that has not appeared to cause any problems with my SD card so far.
However, note that mainline is missing quite a few things, such as support for CPU frequency scaling. (The Armada 3720 gets pretty toasty! I put a heatsink on mine. It only helps a little bit.)
I have the 1GB EspressoBin with no onboard eMMC and I don’t have the wireless card, so I don’t have advice on how to make wireless work. I also haven’t tried SATA or USB with it.