[U-Boot] SPI in U-Boot on Raspberry Pi for TPM 2.0

[Torben]

Hi,

does anyone know, if it is possible to use SPI in U-Boot on a Raspberry 
Pi 3 Model B?

What I'm trying to achieve:
- Connect a TPM 2.0 via SPI to the Raspberry Pi and communicate with it

What I already have:
- Compiled U-Boot with support for Raspberry Pi 3 Model B; I can access 
the console and I can boot Raspbian from the SD-card

Questions / Problems:
- How do I activate SPI support? I have enabled CONFIG_SPI, 
CONFIG_CMD_SPI and CONFIG_DM_SPI. I guess, I'd have also have to enable 
some Raspberry Pi specific SPI driver to make it work?

-> It seems like there is no driver for it, yet? (as far as I understand 
this: there would need to be a bcm2835 SPI driver, right?)

-> Would it be possible to alternatively use the SOFT_SPI driver (maybe 
that's also the easier way?)? (because it seems like one can access the 
GPIOs from U-Boot already, so that seems to be implemented) However, I 
can't find much about how this needs to be setup. BTW the U-Boot README 
references to the file "include/configs/sacsng.h" for an example, but 
that file doesn't exist anymore in the current master.

Thanks!
Torben