USB_CFG0
ret = lan78xx_read_reg(dev, USB_CFG0, &buf);
ret = lan78xx_read_reg(dev, USB_CFG0, &buf);
ret = lan78xx_write_reg(dev, USB_CFG0, buf);
ret = lan78xx_read_reg(dev, USB_CFG0, &buf);
ret = lan78xx_write_reg(dev, USB_CFG0, buf);