I'm probably describing what I want incorrectly with 'memory mapped IO'. All I'm after is GPIO, SPI and I2C directly attached to the real processor, as you get

I'm probably describing what I want incorrectly with 'memory mapped IO'. All I'm after is GPIO, SPI and I2C directly attached to the real processor, as you get with a completely standard Raspberry Pi or Rockchip board, but apparently never on x86.