Linux drivers for RTL8211E integrated transceiver device

TB-96AIoT board RK1808

I am trying to implement the ‘Disable CLK125’ option in the RTL8211E integrated transceiver device. (page 40) I am also trying to enable the RXC SSC (Spread Spectrum Clocking) option. (page 45)

manual link: https://github.com/alinxalinx/AX7010/blob/master/DATASHEET/GPHY/RTL8211E(G)-VB(VL)-CG_DataSheet_1%208.pdf

I have tried to find the driver code in the kernel for this to make the appropriate changes but have had no success. There is a realtek.c source file in the kernel at kernel/drivers/net/phy/realtek.c which contains code that looks like it could be modified to give this function but this module is not enabled in the kernel build.

I cannot find how to create or modify existing kernel code to give this access to RTL8211 registers. The file path I have traced to so far is kernel/drivers/net/ethernet/stmicro/stmac/dwmac-rk.c but cannot see how this relates to the RTL8211E driver code to set registers on this device.

Can anyone help in pointing me in the right direction as to where these files are which will give me access to the RTL8211E ?