I am struggling to access the mikrobus pins (and therefore any Click boards) through the PolarFire SOC, on an Icicle board. I am running Linux, with the latest releases from git (2021.4).
Goal: transmit arbitrary data through mikrobus UART, SPI, I2C.
Status: Cannot access UART via linux.
Researched pin outs and confirmed that MSS complex enabled MMUART4, that MMUART4 is pinned to outputs at the top level of the SoC, and that the pins are defined in the physical constraint files, matching the pins on the schematic (TX on B20, RX on A21).
When running linux, only 3 UARTs are shown when “cat /proc/iomem”. I opened up the file meta-polarfire-soc-yocto-bsp/0004-dts-Add-device-tree-for-Microchip-Icicle-Kit.patch at master · polarfire-soc/meta-polarfire-soc-yocto-bsp · GitHub
and I only saw four UARTs in there (that makes sense based on what’s observed in linux).
Can any of you please help suggest how to get the MMUART4 visible within linux? Same question would apply to the QSPI that is pinned out to the microbus.