phy link检测机制记录

当我们在注册miibus的时候devm_mdiobus_register，会去扫描phy设备，如果扫描到以后会注册phydevice设备。然后我们可以使用mdiobus_get_phy来获取扫描到的设备，这个注册Phy设备的时候，会给phy设备创建一个work。
mdiobus_scan->get_phy_device->phy_device_create ->INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine);

struct phy_device *phy_device_create(struct mii_bus *bus, int addr, u32 phy_id,
				     bool is_c45,
				     struct phy_c45_device_ids *c45_ids)
{
   
   
	struct phy_device *dev;
	struct mdio_device *mdiodev;
	int ret = 0;

	/* We allocate the device, and initialize the default values */
	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return ERR_PTR(-ENOMEM);

	mdiodev = &dev->mdio;
	mdiodev->dev.parent = &bus->dev;
	mdiodev->dev.bus = &mdio_bus_type;
	mdiodev->dev.type = &mdio_bus_phy_type;
	mdiodev->bus = bus;
	mdiodev->bus_match = phy_bus_match;
	mdiodev->addr = addr;
	mdiodev->flags = MDIO_DEVICE_FLAG_PHY;
	mdiodev->device_free = phy_mdio_device_free;
	mdiodev->device_remove = phy_mdio_device_remove;

	dev->speed = SPEED_UNKNOWN;
	dev->duplex = DUPLEX_UNKNOWN;
	dev->pause = 0;
	dev->asym_pause = 0;
	dev->link = 0;
	dev->interface = PHY_INTERFACE_MODE_GMII;

	dev->autoneg = AUTONEG_ENABLE;

	dev->is_c45 = is_c45;
	dev->phy_id = phy_id;
	if (c45_ids)
		dev->c45_ids = *c45_ids;
	dev->irq = bus->irq[addr];
	dev_set_name(&mdiodev->dev, PHY_ID_FMT, bus->id, addr);

	dev->state = PHY_DOWN;

	mutex_init(&dev->lock);
	INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine); //work

	/* Request the appropriate module unconditionally; don't
	 * bother trying to do so only if it isn't already loaded,
	 * because that gets complicated. A hotplug event would have
	 * done an unconditional modprobe anyway.
	 * We don't do normal hotplug because it won't work for MDIO
	 * -- because it relies on the device staying around for long
	 * enough for the driver to get loaded. With MDIO, the NIC
	 * driver will get bored and give up as soon as it finds that
	 * there's no driver _already_ loaded.
	 */
	if (is_c45 && c45_ids) {
   
   
		const int num_ids = ARRAY_SIZE(c45_ids->device_ids);
		int i;

		for (i = 1; i < num_ids; i++) {
   
   
			if (c45_ids->device_ids[i] == 0xffffffff)
				continue;

			ret = phy_request_driver_module(dev,
						c45_ids->device_ids[i]);
			if (ret)
				break;
		}
	} else {
   
   
		ret = phy_request_driver_module(dev, phy_id);
	}

	if (!ret) {
   
   
		device_initialize(&mdiodev->dev);
	} else {
   
   
		kfree(dev);
		dev = ERR_PTR(ret);
	}

	return dev;
}

/**
 * phy_state_machine - Handle the state machine
 * @work: work_struct that describes the work to be done
 */
void phy_state_machine(struct work_struct *work)
{
   
   
	struct delayed_work *dwork = to_delayed_work(work);
	struct phy_device *phydev =
			container_of(dwork, struct phy_device, state_queue);
	bool needs_aneg = false, do_suspend = false;
	enum phy_state old_state;
	int err = 0;

	mutex_lock(&phydev->lock);

	old_state = phydev->state;

	switch (phydev->state) {
   
   
	case PHY_DOWN:
	case PHY_READY:
		break;
	case PHY_UP:
		needs_aneg = true;

		break;
	case PHY_NOLINK:
	case PHY_RUNNING:
		err = phy_check_link_status(phydev);  //检测Phy状态
		break;
	case PHY_HALTED:
		if (phydev->link) {
   
   
			phydev->link = 0;
			phy_link_down(phydev, true); //通告phy的down状态
		}
		do_suspend = true;
		break;
	}

	mutex_unlock(&phydev->lock);

	if (needs_aneg)
		err = phy_start_aneg(phydev);
	else if (do_suspend)
		phy_suspend(phydev);

	if (err < 0)
		phy_error(phydev);

	if (old_state != phydev->state) {
   
   
		phydev_dbg