[U-Boot] [PATCH 0/2] sunxi: Single u-boot binary for Allwinner A10/A13/A20 devices

[Siarhei Siamashka]

This patchset introduces the initial rudimentary support for having
just a single u-boot binary for certain subsets of Allwinner A10/A13/A20
devices.

== Example 1: All Allwinner A10/A13/A20 devices

We are restricted to only a very basic common subset of peripherals
(anything that is supported by BROM should be fine). This provides
a possibility to at least boot from the SD card and use some slow
fail-safe DRAM settings. UART, USB and HDMI settings are also
relatively easy to detect at runtime. This provides a possibility
to implement universal installers, which would somehow boot the
system and allow the user to change u-boot and dtb to something
more suitable for his hardware.

Advantages: just works everywhere
Disadvantages: poor performance and very limited set of supported peripherals

== Example 2: Sibling A10/A20 boards (such as Cubieboard1/Cubieboard2)

Some development boards are using exactly the same PCB for one variant
with Allwinner A10 SoC and another variant with Allwinner A20 SoC.
Instead of having two u-boot configurations and two incompatible
u-boot binaries, it is possible to re-use the same u-boot binary
for both of these boards.

Advantages: no performance or feature sacrifices
Disadvantages: only two boards are supported by a single u-boot binary
               (not a big overall improvement)

== Example 3: Univarsal u-boot binary and the settings in non-volatile memory

Most of Allwinner devices have NAND. Booting from NAND is supported by
BROM, so there is no reason why u-boot SPL can't read it too. Some
reserved area in NAND can store the whole DTB file, or even just a
DTB name (a key for lookup somewhere else). Additionally, DRAM timings
and unit specific tuning may be stored there too. This might be implemented
in a (not so) distant future.

Advantages: no performance of feature sacrifices, support for a large
            subset of devices
Disadvantages: somebody has to prepare the correct information in NAND
               (it could be the device vendor, or maybe some reliability
               testing/validation tool, etc.)


Anyway, this is just the beginning. And we have to start with something
simple. These two patches just provide an option for a single universal
u-boot binary with just UART and MMC support (essentially, the example 1).

The patches depend on
    https://patchwork.ozlabs.org/patch/375971/
and
    http://lists.denx.de/pipermail/u-boot/2014-August/185200.html


Siarhei Siamashka (2):
  sunxi: Replace CONFIG_SUN[457]I ifdefs with SOC_IS_SUN[457]I() calls
  sunxi: Universal Allwinner A10/A13/A20 u-boot binary support

 arch/arm/Kconfig                                |   3 +
 arch/arm/cpu/armv7/sunxi/Makefile               |   2 +
 arch/arm/cpu/armv7/sunxi/board.c                |  98 +++++++++++---
 arch/arm/cpu/armv7/sunxi/clock_sun4i.c          |  10 +-
 arch/arm/cpu/armv7/sunxi/cpu_info.c             |  37 ++---
 arch/arm/cpu/armv7/sunxi/dram.c                 | 171 ++++++++++++------------
 arch/arm/include/asm/arch-sunxi/sys_proto.h     |   5 +
 board/sunxi/Kconfig                             |  20 +++
 board/sunxi/MAINTAINERS                         |   7 +
 board/sunxi/Makefile                            |   1 +
 board/sunxi/board.c                             |   1 +
 board/sunxi/dram_sunxi_ddr3_failsafe.c          |  28 ++++
 configs/sunxi-generic-a10-a13-a20_FEL_defconfig |   4 +
 configs/sunxi-generic-a10-a13-a20_defconfig     |   4 +
 include/configs/sun4i.h                         |   2 +
 include/configs/sun4i_sun5i_sun7i.h             |  38 ++++++
 include/configs/sun5i.h                         |   2 +
 include/configs/sun7i.h                         |   2 +
 include/configs/sunxi-common.h                  |  12 ++
 19 files changed, 322 insertions(+), 125 deletions(-)
 create mode 100644 board/sunxi/dram_sunxi_ddr3_failsafe.c
 create mode 100644 configs/sunxi-generic-a10-a13-a20_FEL_defconfig
 create mode 100644 configs/sunxi-generic-a10-a13-a20_defconfig
 create mode 100644 include/configs/sun4i_sun5i_sun7i.h

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1.8.3.2