rk3399: Loading OP-TEE by SPL?

[Christoph Fritz]

Hello,

my goal is to load OP-TEE after BL31 and before u-boot, so I enabled
CONFIG_SPL_OPTEE_IMAGE.

But it fails to build (tested current master):

 $ make -j$(nproc) CROSS_COMPILE=aarch64-linux-gnu- rock-pi-4-rk3399_defconfig all

./arch/arm/include/asm/unified.h: Assembler messages:
./arch/arm/include/asm/unified.h:12: Error: unknown pseudo-op: `.syntax'
common/spl/spl_optee.S:11: Error: operand 1 must be an integer register -- `mov pc,r3'
make[3]: *** [scripts/Makefile.build:292: spl/common/spl/spl_optee.o] Error 1
make[2]: *** [scripts/Makefile.spl:533: spl/common/spl] Error 2
make[2]: *** Waiting for unfinished jobs....

Without CONFIG_SPL_OPTEE_IMAGE the board starts like this:
 TPL -> SPL -> BL31 -> u-boot

What's the correct way to start OP-TEE on rk3399?

Any ideas?

Thanks
  -- Christoph