aml_ddr.fw is a proprietary AArch64 binary ran by BL2 and containing most of the DDR init code. As such, a lot (but not all!) of the BL2 DDR init code has been moved there, presumably because of space restrictions.
Besides, some DDR init code remains in BL2, e.g. PLL init.
Import aml_ddr.fw in Ghidra
aml_ddr.fw cannot be fed into Ghidra directly. It seems to have some sort of header and is LZ4-compressed.
Strip the header:
$ dd if=aml_ddr.fw of=aml_ddr.stripped.fw bs=1 skip=96
And decompress it:
$ cat aml_ddr.stripped.fw | lz4 > aml_ddr.final.fw
When importing into ghidra it will display this notice:
The file aml_ddr.final.fw seems to have nested files in it. Select an import mode:
[ Single file ] [ Batch ] [ File System ] [ Cancel ]Choose File System, then lz4f_decompressed, then set the language to AARCH64 v8A little endian, and the base address to 0xfffd0060.