phyfix.c

// Userspace ethernet PHY fix for Pine64
// by khenriks@ 2018-03-18
// Free to use and distribute under BSD-2-Clause style license, e.g.
// https://choosealicense.com/licenses/bsd-2-clause/

#include <stdint.h>
#include <string.h>

#include <linux/ethtool.h>
#include <linux/mdio.h>
#include <linux/sockios.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

uint8_t get_phy_address(const char* iface) {
  struct ethtool_cmd eth;
  eth.cmd = ETHTOOL_GSET;

  struct ifreq ifr;
  strcpy(ifr.ifr_name, iface);
  ifr.ifr_data = (char*)&eth;

  int fd = socket(AF_INET, SOCK_DGRAM, 0);
  ioctl(fd, SIOCETHTOOL, &ifr);

  return eth.phy_address;
}

int simple_phy_write(const char* iface, uint16_t phy_id, uint16_t reg,
		     uint16_t val) {
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(ifr));

  strcpy(ifr.ifr_name, iface);

  struct mii_ioctl_data* mii = (struct mii_ioctl_data*)(&ifr.ifr_data);
  mii->phy_id = phy_id;
  mii->reg_num = reg;
  mii->val_in = val;

  int fd = socket(AF_INET, SOCK_DGRAM, 0);
  return ioctl(fd, SIOCSMIIREG, &ifr);
}

int main() {
  const char* iface = "eth0";

  const uint8_t phy_id = get_phy_address(iface);

  simple_phy_write(iface, phy_id, 0x1f, 0x0007);
  simple_phy_write(iface, phy_id, 0x1e, 0x00a4);
  simple_phy_write(iface, phy_id, 0x1c, 0xb591);
  simple_phy_write(iface, phy_id, 0x1f, 0x0000);
}