Source code for ESP32-SOLO-1 firmware on HiFive1?

Is there any source code for the firmware of the ESP32-SOLO-1 installed on the HiFive1 revB? I’ve identified a bug with the way the ESP32 firmware is configured to handle the MISO/SDO line, and I’d like to fix it.

Specifically, the ESP32 never releases (always holds low) the MISO line, preventing adding other SPI devices to the SPI bus. I confirmed this by checking the amount of current being drawn by the ESP32 on that pin (should be DIG12 in one of the headers header in the schematics) while toggling the CS2 line. That pin is always drawing 38mA with a 3.3V voltage applied to that pin, which is a pretty clear indication that it’s being held low.

To test my theory, I’ve also flashed a custom application to the ESP32 which does nothing, and with that in place, all the SPI lines work normally, and DIG12 is no longer being held low by the ESP32, so the problem I’m running into must be caused by the default firmware.

I am aware that the firmware the ESP32 is some derivative of the ESP-AT project, but I’m not 100% sure what patches were added after the fact, as upstream does not support SPI-AT with the ESP32-SOLO-1, only with the ESP32C3. Would it be possible to get a copy of the source code used to build the ESP32 firmware shipped with the HiFive1 revB?