> > But what does that have to do with the misc device? >
Hi Greg, MFD driver is the start of everything. Once MFD driver is loading, it will spawn 2 devices, one is for phc driver, which is under /driver/ptp and the other one is for this misc driver. Both PHC and misc drivers are operating on the same device. They are both calling exported functions from mfd drivers to access the device through i2c/spi and the register definitions are located in include/Linux/mfd/idt8a340_reg.h or idt82p33_reg.h depending on which device was found by mfd driver through device tree node.
