Hello Yaron Alterman,
SMC functions treat registers x0-x12 as volatile, to call an SMC/PSCI function, load the registers according to the table below, then execute an “SMC 0x0” instruction. Please refer to "smc #0" invoking in the file arch/arm/cpu/armv8/sec_firmware_asm.S of u-boot source code.
The procedure for loading and initialize PPA.
1. The PPA must be loaded to a 64Kb boundary
2. Copy the binary image to the load address – the component installing the PPA MUST be executing at EL3
3. PPA should be loaded to an address in secure memory - recommend a 2MB secure region in DDR (but PPA can be tested in non-secure DDR)
4. After copying the image file to DDR, clean the data cache by VA (all virtual address ranges affected by PPA load) , and invalidate the instruction cache.
5. The PPA initialization runs at EL3 – but the PPA transfers control back to the address loaded in BOO TLOCPTR at EL2 –you must write the start address of the EL2 portion of your bootloader into BOOTLOCPTR before initializing the PPA.
6. After writing the EL2 start address in BOOTLOCPTR, initialize the PPA by branching to its start address
Have a great day,
TIC
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------
