[U-Boot] [PATCH 3/6] sunxi: add Cubieboard2 support

[Siarhei Siamashka <siarhei.siamashka@gmail.com>]

On Thu,  5 Jun 2014 19:00:14 +0100
Ian Campbell <ijc@hellion.org.uk> wrote:

> This is a sun7i (A20) based followup to the sun4i (A10)
> Cubieboard. It has GMAC using MII mode.
> 
> Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
> Acked-by: Hans de Goede <hdegoede@redhat.com>

This board is using exactly the same PCB as the Cubieboard1. And only
the SoC is different (Allwinner A20 instead of the pin-compatible
Allwinner A10).

Before piling up more board configurations, we might want to consider
supporting both Cubieboard1 and Cubieboard2 with a single u-boot binary
(and perhaps keep Cubieboard1 and Cubieboard2 as aliases in boards.cfg).
The Allwinner SoCs have support for runtime identification of the SoC
type (sun4i/sun5i/sun7i) via the VER_REG (Version Register) located at
the address 0x01C00024 as explained in the Allwinner A20 user manual.
This requires replacing all the CONFIG_SUN4I/CONFIG_SUN5I/CONFIG_SUN7I
ifdefs in the u-boot code with a runtime SoC type checks, but there
are not too many places affected (mostly just the DRAM code).

Here is a quick and dirty example (not a patch submission yet), which
allows to boot the Cubieboard2 hardware using the existing Cubieboard1
config:
    https://github.com/ssvb/u-boot-sunxi-dram/commit/3153905e0221

If the u-boot code is further extended to define a variable with the
relevant dtb file name in the u-boot environment (depending on the
runtime detected SoC type and selecting from "sun4i-a10-cubieboard.dtb"
and "sun7i-a20-cubieboard2.dtb"), then we can have the same SD card
with the whole pre-installed Linux system usable on both Cubieboard1
and Cubieboard2 hardware by just swapping the card.

Also the Cubieboards are not alone. Sharing the same PCB happens for
the LIME boards from Olimex too:
   https://www.olimex.com/Products/OLinuXino/A10/A10-OLinuXino-LIME
   https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXino-LIME

>  Active  arm         armv7          sunxi       -               sunxi               Cubieboard                            sun4i:CUBIEBOARD,SPL,AXP209_POWER,SUNXI_EMAC                                                                                      Hans de Goede <hdegoede@redhat.com>
> +Active  arm         armv7          sunxi       -               sunxi               Cubieboard2                           sun7i:CUBIEBOARD2,SPL,SUNXI_GMAC                                                                                                  Ian Campbell <ijc@hellion.org.uk>:Hans de Goede <hdegoede@redhat.com>
> +Active  arm         armv7          sunxi       -               sunxi               Cubieboard2_FEL                       sun7i:CUBIEBOARD2,SPL_FEL,SUNXI_GMAC                                                                                              Ian Campbell <ijc@hellion.org.uk>:Hans de Goede <hdegoede@redhat.com>

The newly added Cubieboard2 from your patch appears to be missing the
important AXP209_POWER option. So the patch is not good enough to be
pushed anywhere in its current form.

-- 
Best regards,
Siarhei Siamashka