[U-Boot] [PATCH 2/2] ARM: add Raspberry Pi 3 64-bit config

[Stephen Warren]

On 04/02/2016 07:26 AM, Tom Rini wrote:
> On Fri, Apr 01, 2016 at 09:14:15PM -0600, Stephen Warren wrote:
>
>> On all Pis so far, the VC FW provides a short stub to set up the ARM CPU
>> before entering the kernel (a/k/a U-Boot for us). This feature is not
>> currently supported by the VC FW when booting in 64-bit mode. However,
>> this feature will likely appear in the near future, and this U-Boot port
>> assumes that such a feature is in place. Without that feature, or a
>> temporary workaround described below, U-Boot will not boot.
>>
>> Once the VC FW does provide the ARM stub, u-boot.bin built for rpi_3 can
>> be used drectly as kernel7.img, in the same way as any other RPi port. The
>> following config.txt is required:
>>
>>      # Fix mini UART input frequency, and setup/enable up the UART.
>>      # Without this option, U-Boot will not boot, even if you don't care
>>      # about the serial console. This option will always be required for
>>      # all RPi3 use-cases, unless the PL011 UART is used, which is not
>>      # yet supported by rpi_3* builds of U-Boot.
>>      enable_uart=1
>>      # Boot in AArch64 (64-bit) mode.
>>      # It is possible that a future VC FW will remove the need for this
>>      # option, instead auto-setting 32-/64-bit mode based on the "kernel"
>>      # filename present on the SD card.
>>      arm_control=0x200
>>
>> Prior to the VC FW providing the ARM boot stub, you can use the following
>> steps to build an equivalent stub into the U-Boot binary:
>>
>> git clone https://github.com/swarren/rpi-3-aarch64-demo.git \
>>      ../rpi-3-aarch64-demo
>> (cd ../rpi-3-aarch64-demo && ./build.sh)
>> Build U-Boot for rpi_3 in the usual way
>> cat ../rpi-3-aarch64-demo/armstub64.bin u-boot.bin > u-boot.bin.stubbed
>> Use u-boot.bin.stubbed as kernel7.img on the Pi SD card.
>>
>> In this case, the following additional entries are required in config.txt:
>>
>>      # Tell the FW to load the kernel image at address 0, the reset vector.
>>      kernel_old=1
>>
>> Signed-off-by: Stephen Warren <swarren at wwwdotorg.org>
>
> As our infrastructure stands today:
> Reviewed-by: Tom Rini <trini at konsulko.com>
>
> But would it be possible to clean things up and consolidate files?  If
> CONFIG_SYS_CACHLINE_SIZE and CONFIG_SKIP_LOWLEVEL_INIT were in Kconfig
> it looks like everything could live in board/raspberrypi/rpi/ which it
> nearly does today.  If it's hard, I'd be OK punting that to v2015.07.
> Or am I missing something?

It looks like there is a way to remove a lot of the duplicate board/ 
directories, and I can put a few ifdefs into the config header to 
combine them into just one. I'll send a patch soon.