CTL_STATUS_t ctl_mac_mii_read(CTL_NET_INTERFACE_t *net, int reg);
ctl_mac_mii_read busy-waits until the result is available. This is a wrapper around the mii_read_fn member of the network MAC driver.
The valid range for devAddr is 0 through 31 and needs to match the PHY chip's physical address, which is typically set on the PHY hardware using strapping pins. See your PHY chip's datasheet for valid values of reg. Return values are negative for failure, a number between 0 and 0xFFFF (inclusive) for success.