hw/arm/allwinner-h3: add Boot ROM support
A real Allwinner H3 SoC contains a Boot ROM which is the
first code that runs right after the SoC is powered on.
The Boot ROM is responsible for loading user code (e.g. a bootloader)
from any of the supported external devices and writing the downloaded
code to internal SRAM. After loading the SoC begins executing the code
written to SRAM.
This commits adds emulation of the Boot ROM firmware setup functionality
by loading user code from SD card in the A1 SRAM. While the A1 SRAM is
64KiB, we limit the size to 32KiB because the real H3 Boot ROM also rejects
sizes larger than 32KiB. For reference, this behaviour is documented
by the Linux Sunxi project wiki at:
https://linux-sunxi.org/BROM#U-Boot_SPL_limitations
Signed-off-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id:
20200311221854.30370-11-nieklinnenbank@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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