[U-Boot] ARM: sama5d2: Implement boot device autodetection

[Marek Vasut <marex@denx.de>]

On 05/03/2016 10:52 AM, Andreas Bie?mann wrote:
> On Fri, Apr 22, 2016 at 09:56:21PM +0200, Marek Vasut wrote:
>> Implement support for saving ARM register R4 early during boot using
>> save_boot_params . Implement support for decoding the stored register
>> R4 value in spl_boot_device() to obtain boot device from which the
>> SoC booted. This way, the SPL will always load U-Boot from the same
>> device from which the SPL itself booted instead of using hard-coded
>> boot device.
>>
>> This functionality is useful for example when booting sama5d2-xplained
>> from SD card, where by default the SPL would try loading the U-Boot
>> from eMMC and fail. This is because eMMC is on SDHCI0 (BOOT_DEVICE_MMC1),
>> while SD slot is on SDHCI1 (BOOT_DEVICE_MMC2) and the SPL was hard-wired
>> to always boot from BOOT_DEVICE_MMC1.
>>
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Cc: Andreas Bie?mann <andreas.devel@googlemail.com>
>> Cc: Wenyou Yang <wenyou.yang@atmel.com>
>>
> 
> Reviewed-by: Andreas Bie?mann <andreas@biessmann.org>

I will eventually extend this to SAMA5Dx as this is quite helpful on
upcoming board.

>> ---
>>  arch/arm/mach-at91/Makefile               |  2 +-
>>  arch/arm/mach-at91/bootparams_atmel.S     | 18 ++++++++++++++++
>>  arch/arm/mach-at91/include/mach/sama5d2.h | 12 +++++++++++
>>  arch/arm/mach-at91/spl.c                  | 36 +++++++++++++++++++++++++++++++
>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>  create mode 100644 arch/arm/mach-at91/bootparams_atmel.S


-- 
Best regards,
Marek Vasut