MDIO_SINGLE_CMD
for (i = 0; readl_relaxed(base + MDIO_SINGLE_CMD) & MDIO_START; i++) {
writel_relaxed(MDIO_READ | phy << 8 | reg, base + MDIO_SINGLE_CMD);
writel_relaxed(MDIO_WRITE | phy << 8 | reg, base + MDIO_SINGLE_CMD);