Fingerprint sensor on Pocophone F1
The Pocophone F1 has a fingerprint sensor attached over SPI as shown on the schematics:
The SPI signals (MISO,MOSI, CLK, CS_N) lead to the SDM845 SoC as shown here:
The node is defined here in the device tree of the Xiaomi downstream kernel.
The device tree does not specify the area for the GPIO pins nor for the SPI interface as reserved which means that it should be possible to touch those registers, right?
However, not specifying reserved memory doesn't mean the Trust Zone (qseecom
, or what Xiaomi uses) is not checking the memory access and will halt the "less" security privileged Linux kernel.