drivers/net/phy/mdio_bus.c - linux/kernel/git/viro/vfs - Git at Google

 /*
  * drivers/net/phy/mdio_bus.c
  *
  * MDIO Bus interface
  *
  * Author: Andy Fleming
  *
  * Copyright (c) 2004 Freescale Semiconductor, Inc.
  *
  * This program is free software; you can redistribute  it and/or modify it
  * under  the terms of  the GNU General  Public License as published by the
  * Free Software Foundation;  either version 2 of the  License, or (at your
  * option) any later version.
  *
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/unistd.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/skbuff.h>
 #include <linux/spinlock.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/mii.h>
 #include <linux/ethtool.h>
 #include <linux/phy.h>

 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/uaccess.h>

 /**
  * mdiobus_alloc_size - allocate a mii_bus structure
  * @size: extra amount of memory to allocate for private storage.
  * If non-zero, then bus->priv is points to that memory.
  *
  * Description: called by a bus driver to allocate an mii_bus
  * structure to fill in.
  */
 struct mii_bus *mdiobus_alloc_size(size_t size)
 {
 	struct mii_bus *bus;
 	size_t aligned_size = ALIGN(sizeof(*bus), NETDEV_ALIGN);
 	size_t alloc_size;

 	/* If we alloc extra space, it should be aligned */
 	if (size)
 		alloc_size = aligned_size + size;
 	else
 		alloc_size = sizeof(*bus);

 	bus = kzalloc(alloc_size, GFP_KERNEL);
 	if (bus) {
 		bus->state = MDIOBUS_ALLOCATED;
 		if (size)
 			bus->priv = (void *)bus + aligned_size;
 	}

 	return bus;
 }
 EXPORT_SYMBOL(mdiobus_alloc_size);

 /**
  * mdiobus_release - mii_bus device release callback
  * @d: the target struct device that contains the mii_bus
  *
  * Description: called when the last reference to an mii_bus is
  * dropped, to free the underlying memory.
  */
 static void mdiobus_release(struct device *d)
 {
 	struct mii_bus *bus = to_mii_bus(d);
 	BUG_ON(bus->state != MDIOBUS_RELEASED &&
 	       /* for compatibility with error handling in drivers */
 	       bus->state != MDIOBUS_ALLOCATED);
 	kfree(bus);
 }

 static struct class mdio_bus_class = {
 	.name		= "mdio_bus",
 	.dev_release	= mdiobus_release,
 };

 #if IS_ENABLED(CONFIG_OF_MDIO)
 /* Helper function for of_mdio_find_bus */
 static int of_mdio_bus_match(struct device *dev, const void *mdio_bus_np)
 {
 	return dev->of_node == mdio_bus_np;
 }
 /**
  * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
  * @mdio_bus_np: Pointer to the mii_bus.
  *
  * Returns a pointer to the mii_bus, or NULL if none found.
  *
  * Because the association of a device_node and mii_bus is made via
  * of_mdiobus_register(), the mii_bus cannot be found before it is
  * registered with of_mdiobus_register().
  *
  */
 struct mii_bus *of_mdio_find_bus(struct device_node *mdio_bus_np)
 {
 	struct device *d;

 	if (!mdio_bus_np)
 		return NULL;

 	d = class_find_device(&mdio_bus_class, NULL,  mdio_bus_np,
 			      of_mdio_bus_match);

 	return d ? to_mii_bus(d) : NULL;
 }
 EXPORT_SYMBOL(of_mdio_find_bus);
 #endif

 /**
  * mdiobus_register - bring up all the PHYs on a given bus and attach them to bus
  * @bus: target mii_bus
  *
  * Description: Called by a bus driver to bring up all the PHYs
  *   on a given bus, and attach them to the bus.
  *
  * Returns 0 on success or < 0 on error.
  */
 int mdiobus_register(struct mii_bus *bus)
 {
 	int i, err;

 	if (NULL == bus || NULL == bus->name ||
 			NULL == bus->read ||
 			NULL == bus->write)
 		return -EINVAL;

 	BUG_ON(bus->state != MDIOBUS_ALLOCATED &&
 	       bus->state != MDIOBUS_UNREGISTERED);

 	bus->dev.parent = bus->parent;
 	bus->dev.class = &mdio_bus_class;
 	bus->dev.groups = NULL;
 	dev_set_name(&bus->dev, "%s", bus->id);

 	err = device_register(&bus->dev);
 	if (err) {
 		pr_err("mii_bus %s failed to register\n", bus->id);
 		return -EINVAL;
 	}

 	mutex_init(&bus->mdio_lock);

 	if (bus->reset)
 		bus->reset(bus);

 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		if ((bus->phy_mask & (1 << i)) == 0) {
 			struct phy_device *phydev;

 			phydev = mdiobus_scan(bus, i);
 			if (IS_ERR(phydev)) {
 				err = PTR_ERR(phydev);
 				goto error;
 			}
 		}
 	}

 	bus->state = MDIOBUS_REGISTERED;
 	pr_info("%s: probed\n", bus->name);
 	return 0;

 error:
 	while (--i >= 0) {
 		if (bus->phy_map[i])
 			device_unregister(&bus->phy_map[i]->dev);
 	}
 	device_del(&bus->dev);
 	return err;
 }
 EXPORT_SYMBOL(mdiobus_register);

 void mdiobus_unregister(struct mii_bus *bus)
 {
 	int i;

 	BUG_ON(bus->state != MDIOBUS_REGISTERED);
 	bus->state = MDIOBUS_UNREGISTERED;

 	device_del(&bus->dev);
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		if (bus->phy_map[i])
 			device_unregister(&bus->phy_map[i]->dev);
 		bus->phy_map[i] = NULL;
 	}
 }
 EXPORT_SYMBOL(mdiobus_unregister);

 /**
  * mdiobus_free - free a struct mii_bus
  * @bus: mii_bus to free
  *
  * This function releases the reference to the underlying device
  * object in the mii_bus.  If this is the last reference, the mii_bus
  * will be freed.
  */
 void mdiobus_free(struct mii_bus *bus)
 {
 	/*
 	 * For compatibility with error handling in drivers.
 	 */
 	if (bus->state == MDIOBUS_ALLOCATED) {
 		kfree(bus);
 		return;
 	}

 	BUG_ON(bus->state != MDIOBUS_UNREGISTERED);
 	bus->state = MDIOBUS_RELEASED;

 	put_device(&bus->dev);
 }
 EXPORT_SYMBOL(mdiobus_free);

 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
 {
 	struct phy_device *phydev;
 	int err;

 	phydev = get_phy_device(bus, addr, false);
 	if (IS_ERR(phydev) || phydev == NULL)
 		return phydev;

 	err = phy_device_register(phydev);
 	if (err) {
 		phy_device_free(phydev);
 		return NULL;
 	}

 	return phydev;
 }
 EXPORT_SYMBOL(mdiobus_scan);

 /**
  * mdiobus_read - Convenience function for reading a given MII mgmt register
  * @bus: the mii_bus struct
  * @addr: the phy address
  * @regnum: register number to read
  *
  * NOTE: MUST NOT be called from interrupt context,
  * because the bus read/write functions may wait for an interrupt
  * to conclude the operation.
  */
 int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 {
 	int retval;

 	BUG_ON(in_interrupt());

 	mutex_lock(&bus->mdio_lock);
 	retval = bus->read(bus, addr, regnum);
 	mutex_unlock(&bus->mdio_lock);

 	return retval;
 }
 EXPORT_SYMBOL(mdiobus_read);

 /**
  * mdiobus_write - Convenience function for writing a given MII mgmt register
  * @bus: the mii_bus struct
  * @addr: the phy address
  * @regnum: register number to write
  * @val: value to write to @regnum
  *
  * NOTE: MUST NOT be called from interrupt context,
  * because the bus read/write functions may wait for an interrupt
  * to conclude the operation.
  */
 int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 {
 	int err;

 	BUG_ON(in_interrupt());

 	mutex_lock(&bus->mdio_lock);
 	err = bus->write(bus, addr, regnum, val);
 	mutex_unlock(&bus->mdio_lock);

 	return err;
 }
 EXPORT_SYMBOL(mdiobus_write);

 /**
  * mdio_bus_match - determine if given PHY driver supports the given PHY device
  * @dev: target PHY device
  * @drv: given PHY driver
  *
  * Description: Given a PHY device, and a PHY driver, return 1 if
  *   the driver supports the device.  Otherwise, return 0.
  */
 static int mdio_bus_match(struct device *dev, struct device_driver *drv)
 {
 	struct phy_device *phydev = to_phy_device(dev);
 	struct phy_driver *phydrv = to_phy_driver(drv);

 	if (of_driver_match_device(dev, drv))
 		return 1;

 	if (phydrv->match_phy_device)
 		return phydrv->match_phy_device(phydev);

 	return ((phydrv->phy_id & phydrv->phy_id_mask) ==
 		(phydev->phy_id & phydrv->phy_id_mask));
 }

 #ifdef CONFIG_PM

 static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 {
 	struct device_driver *drv = phydev->dev.driver;
 	struct phy_driver *phydrv = to_phy_driver(drv);
 	struct net_device *netdev = phydev->attached_dev;

 	if (!drv || !phydrv->suspend)
 		return false;

 	/* PHY not attached? May suspend. */
 	if (!netdev)
 		return true;

 	/*
 	 * Don't suspend PHY if the attched netdev parent may wakeup.
 	 * The parent may point to a PCI device, as in tg3 driver.
 	 */
 	if (netdev->dev.parent && device_may_wakeup(netdev->dev.parent))
 		return false;

 	/*
 	 * Also don't suspend PHY if the netdev itself may wakeup. This
 	 * is the case for devices w/o underlaying pwr. mgmt. aware bus,
 	 * e.g. SoC devices.
 	 */
 	if (device_may_wakeup(&netdev->dev))
 		return false;

 	return true;
 }

 static int mdio_bus_suspend(struct device *dev)
 {
 	struct phy_driver *phydrv = to_phy_driver(dev->driver);
 	struct phy_device *phydev = to_phy_device(dev);

 	/*
 	 * We must stop the state machine manually, otherwise it stops out of
 	 * control, possibly with the phydev->lock held. Upon resume, netdev
 	 * may call phy routines that try to grab the same lock, and that may
 	 * lead to a deadlock.
 	 */
 	if (phydev->attached_dev && phydev->adjust_link)
 		phy_stop_machine(phydev);

 	if (!mdio_bus_phy_may_suspend(phydev))
 		return 0;

 	return phydrv->suspend(phydev);
 }

 static int mdio_bus_resume(struct device *dev)
 {
 	struct phy_driver *phydrv = to_phy_driver(dev->driver);
 	struct phy_device *phydev = to_phy_device(dev);
 	int ret;

 	if (!mdio_bus_phy_may_suspend(phydev))
 		goto no_resume;

 	ret = phydrv->resume(phydev);
 	if (ret < 0)
 		return ret;

 no_resume:
 	if (phydev->attached_dev && phydev->adjust_link)
 		phy_start_machine(phydev, NULL);

 	return 0;
 }

 static int mdio_bus_restore(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
 	struct net_device *netdev = phydev->attached_dev;
 	int ret;

 	if (!netdev)
 		return 0;

 	ret = phy_init_hw(phydev);
 	if (ret < 0)
 		return ret;

 	/* The PHY needs to renegotiate. */
 	phydev->link = 0;
 	phydev->state = PHY_UP;

 	phy_start_machine(phydev, NULL);

 	return 0;
 }

 static struct dev_pm_ops mdio_bus_pm_ops = {
 	.suspend = mdio_bus_suspend,
 	.resume = mdio_bus_resume,
 	.freeze = mdio_bus_suspend,
 	.thaw = mdio_bus_resume,
 	.restore = mdio_bus_restore,
 };

 #define MDIO_BUS_PM_OPS (&mdio_bus_pm_ops)

 #else

 #define MDIO_BUS_PM_OPS NULL

 #endif /* CONFIG_PM */

 static ssize_t
 phy_id_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct phy_device *phydev = to_phy_device(dev);

 	return sprintf(buf, "0x%.8lx\n", (unsigned long)phydev->phy_id);
 }
 static DEVICE_ATTR_RO(phy_id);

 static struct attribute *mdio_dev_attrs[] = {
 	&dev_attr_phy_id.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(mdio_dev);

 struct bus_type mdio_bus_type = {
 	.name		= "mdio_bus",
 	.match		= mdio_bus_match,
 	.pm		= MDIO_BUS_PM_OPS,
 	.dev_groups	= mdio_dev_groups,
 };
 EXPORT_SYMBOL(mdio_bus_type);

 int __init mdio_bus_init(void)
 {
 	int ret;

 	ret = class_register(&mdio_bus_class);
 	if (!ret) {
 		ret = bus_register(&mdio_bus_type);
 		if (ret)
 			class_unregister(&mdio_bus_class);
 	}

 	return ret;
 }

 void mdio_bus_exit(void)
 {
 	class_unregister(&mdio_bus_class);
 	bus_unregister(&mdio_bus_type);
 }
	/*
	* drivers/net/phy/mdio_bus.c
	*
	* MDIO Bus interface
	*
	* Author: Andy Fleming
	*
	* Copyright (c) 2004 Freescale Semiconductor, Inc.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the
	* Free Software Foundation; either version 2 of the License, or (at your
	* option) any later version.
	*
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/string.h>
	#include <linux/errno.h>
	#include <linux/unistd.h>
	#include <linux/slab.h>
	#include <linux/interrupt.h>
	#include <linux/init.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/of_device.h>
	#include <linux/of_mdio.h>
	#include <linux/netdevice.h>
	#include <linux/etherdevice.h>
	#include <linux/skbuff.h>
	#include <linux/spinlock.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/mii.h>
	#include <linux/ethtool.h>
	#include <linux/phy.h>

	#include <asm/io.h>
	#include <asm/irq.h>
	#include <asm/uaccess.h>

	/**
	* mdiobus_alloc_size - allocate a mii_bus structure
	* @size: extra amount of memory to allocate for private storage.
	* If non-zero, then bus->priv is points to that memory.
	*
	* Description: called by a bus driver to allocate an mii_bus
	* structure to fill in.
	*/
	struct mii_bus *mdiobus_alloc_size(size_t size)
	{
	struct mii_bus *bus;
	size_t aligned_size = ALIGN(sizeof(*bus), NETDEV_ALIGN);
	size_t alloc_size;

	/* If we alloc extra space, it should be aligned */
	if (size)
	alloc_size = aligned_size + size;
	else
	alloc_size = sizeof(*bus);

	bus = kzalloc(alloc_size, GFP_KERNEL);
	if (bus) {
	bus->state = MDIOBUS_ALLOCATED;
	if (size)
	bus->priv = (void *)bus + aligned_size;
	}

	return bus;
	}
	EXPORT_SYMBOL(mdiobus_alloc_size);

	/**
	* mdiobus_release - mii_bus device release callback
	* @d: the target struct device that contains the mii_bus
	*
	* Description: called when the last reference to an mii_bus is
	* dropped, to free the underlying memory.
	*/
	static void mdiobus_release(struct device *d)
	{
	struct mii_bus *bus = to_mii_bus(d);
	BUG_ON(bus->state != MDIOBUS_RELEASED &&
	/* for compatibility with error handling in drivers */
	bus->state != MDIOBUS_ALLOCATED);
	kfree(bus);
	}

	static struct class mdio_bus_class = {
	.name = "mdio_bus",
	.dev_release = mdiobus_release,
	};

	#if IS_ENABLED(CONFIG_OF_MDIO)
	/* Helper function for of_mdio_find_bus */
	static int of_mdio_bus_match(struct device dev, const void mdio_bus_np)
	{
	return dev->of_node == mdio_bus_np;
	}
	/**
	* of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
	* @mdio_bus_np: Pointer to the mii_bus.
	*
	* Returns a pointer to the mii_bus, or NULL if none found.
	*
	* Because the association of a device_node and mii_bus is made via
	* of_mdiobus_register(), the mii_bus cannot be found before it is
	* registered with of_mdiobus_register().
	*
	*/
	struct mii_bus of_mdio_find_bus(struct device_node mdio_bus_np)
	{
	struct device *d;

	if (!mdio_bus_np)
	return NULL;

	d = class_find_device(&mdio_bus_class, NULL, mdio_bus_np,
	of_mdio_bus_match);

	return d ? to_mii_bus(d) : NULL;
	}
	EXPORT_SYMBOL(of_mdio_find_bus);
	#endif

	/**
	* mdiobus_register - bring up all the PHYs on a given bus and attach them to bus
	* @bus: target mii_bus
	*
	* Description: Called by a bus driver to bring up all the PHYs
	* on a given bus, and attach them to the bus.
	*
	* Returns 0 on success or < 0 on error.
	*/
	int mdiobus_register(struct mii_bus *bus)
	{
	int i, err;

	if (NULL == bus \|\| NULL == bus->name \|\|
	NULL == bus->read \|\|
	NULL == bus->write)
	return -EINVAL;

	BUG_ON(bus->state != MDIOBUS_ALLOCATED &&
	bus->state != MDIOBUS_UNREGISTERED);

	bus->dev.parent = bus->parent;
	bus->dev.class = &mdio_bus_class;
	bus->dev.groups = NULL;
	dev_set_name(&bus->dev, "%s", bus->id);

	err = device_register(&bus->dev);
	if (err) {
	pr_err("mii_bus %s failed to register\n", bus->id);
	return -EINVAL;
	}

	mutex_init(&bus->mdio_lock);

	if (bus->reset)
	bus->reset(bus);

	for (i = 0; i < PHY_MAX_ADDR; i++) {
	if ((bus->phy_mask & (1 << i)) == 0) {
	struct phy_device *phydev;

	phydev = mdiobus_scan(bus, i);
	if (IS_ERR(phydev)) {
	err = PTR_ERR(phydev);
	goto error;
	}
	}
	}

	bus->state = MDIOBUS_REGISTERED;
	pr_info("%s: probed\n", bus->name);
	return 0;

	error:
	while (--i >= 0) {
	if (bus->phy_map[i])
	device_unregister(&bus->phy_map[i]->dev);
	}
	device_del(&bus->dev);
	return err;
	}
	EXPORT_SYMBOL(mdiobus_register);

	void mdiobus_unregister(struct mii_bus *bus)
	{
	int i;

	BUG_ON(bus->state != MDIOBUS_REGISTERED);
	bus->state = MDIOBUS_UNREGISTERED;

	device_del(&bus->dev);
	for (i = 0; i < PHY_MAX_ADDR; i++) {
	if (bus->phy_map[i])
	device_unregister(&bus->phy_map[i]->dev);
	bus->phy_map[i] = NULL;
	}
	}
	EXPORT_SYMBOL(mdiobus_unregister);

	/**
	* mdiobus_free - free a struct mii_bus
	* @bus: mii_bus to free
	*
	* This function releases the reference to the underlying device
	* object in the mii_bus. If this is the last reference, the mii_bus
	* will be freed.
	*/
	void mdiobus_free(struct mii_bus *bus)
	{
	/*
	* For compatibility with error handling in drivers.
	*/
	if (bus->state == MDIOBUS_ALLOCATED) {
	kfree(bus);
	return;
	}

	BUG_ON(bus->state != MDIOBUS_UNREGISTERED);
	bus->state = MDIOBUS_RELEASED;

	put_device(&bus->dev);
	}
	EXPORT_SYMBOL(mdiobus_free);

	struct phy_device mdiobus_scan(struct mii_bus bus, int addr)
	{
	struct phy_device *phydev;
	int err;

	phydev = get_phy_device(bus, addr, false);
	if (IS_ERR(phydev) \|\| phydev == NULL)
	return phydev;

	err = phy_device_register(phydev);
	if (err) {
	phy_device_free(phydev);
	return NULL;
	}

	return phydev;
	}
	EXPORT_SYMBOL(mdiobus_scan);

	/**
	* mdiobus_read - Convenience function for reading a given MII mgmt register
	* @bus: the mii_bus struct
	* @addr: the phy address
	* @regnum: register number to read
	*
	* NOTE: MUST NOT be called from interrupt context,
	* because the bus read/write functions may wait for an interrupt
	* to conclude the operation.
	*/
	int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
	{
	int retval;

	BUG_ON(in_interrupt());

	mutex_lock(&bus->mdio_lock);
	retval = bus->read(bus, addr, regnum);
	mutex_unlock(&bus->mdio_lock);

	return retval;
	}
	EXPORT_SYMBOL(mdiobus_read);

	/**
	* mdiobus_write - Convenience function for writing a given MII mgmt register
	* @bus: the mii_bus struct
	* @addr: the phy address
	* @regnum: register number to write
	* @val: value to write to @regnum
	*
	* NOTE: MUST NOT be called from interrupt context,
	* because the bus read/write functions may wait for an interrupt
	* to conclude the operation.
	*/
	int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
	{
	int err;

	BUG_ON(in_interrupt());

	mutex_lock(&bus->mdio_lock);
	err = bus->write(bus, addr, regnum, val);
	mutex_unlock(&bus->mdio_lock);

	return err;
	}
	EXPORT_SYMBOL(mdiobus_write);

	/**
	* mdio_bus_match - determine if given PHY driver supports the given PHY device
	* @dev: target PHY device
	* @drv: given PHY driver
	*
	* Description: Given a PHY device, and a PHY driver, return 1 if
	* the driver supports the device. Otherwise, return 0.
	*/
	static int mdio_bus_match(struct device dev, struct device_driver drv)
	{
	struct phy_device *phydev = to_phy_device(dev);
	struct phy_driver *phydrv = to_phy_driver(drv);

	if (of_driver_match_device(dev, drv))
	return 1;

	if (phydrv->match_phy_device)
	return phydrv->match_phy_device(phydev);

	return ((phydrv->phy_id & phydrv->phy_id_mask) ==
	(phydev->phy_id & phydrv->phy_id_mask));
	}

	#ifdef CONFIG_PM

	static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
	{
	struct device_driver *drv = phydev->dev.driver;
	struct phy_driver *phydrv = to_phy_driver(drv);
	struct net_device *netdev = phydev->attached_dev;

	if (!drv \|\| !phydrv->suspend)
	return false;

	/* PHY not attached? May suspend. */
	if (!netdev)
	return true;

	/*
	* Don't suspend PHY if the attched netdev parent may wakeup.
	* The parent may point to a PCI device, as in tg3 driver.
	*/
	if (netdev->dev.parent && device_may_wakeup(netdev->dev.parent))
	return false;

	/*
	* Also don't suspend PHY if the netdev itself may wakeup. This
	* is the case for devices w/o underlaying pwr. mgmt. aware bus,
	* e.g. SoC devices.
	*/
	if (device_may_wakeup(&netdev->dev))
	return false;

	return true;
	}

	static int mdio_bus_suspend(struct device *dev)
	{
	struct phy_driver *phydrv = to_phy_driver(dev->driver);
	struct phy_device *phydev = to_phy_device(dev);

	/*
	* We must stop the state machine manually, otherwise it stops out of
	* control, possibly with the phydev->lock held. Upon resume, netdev
	* may call phy routines that try to grab the same lock, and that may
	* lead to a deadlock.
	*/
	if (phydev->attached_dev && phydev->adjust_link)
	phy_stop_machine(phydev);

	if (!mdio_bus_phy_may_suspend(phydev))
	return 0;

	return phydrv->suspend(phydev);
	}

	static int mdio_bus_resume(struct device *dev)
	{
	struct phy_driver *phydrv = to_phy_driver(dev->driver);
	struct phy_device *phydev = to_phy_device(dev);
	int ret;

	if (!mdio_bus_phy_may_suspend(phydev))
	goto no_resume;

	ret = phydrv->resume(phydev);
	if (ret < 0)
	return ret;

	no_resume:
	if (phydev->attached_dev && phydev->adjust_link)
	phy_start_machine(phydev, NULL);

	return 0;
	}

	static int mdio_bus_restore(struct device *dev)
	{
	struct phy_device *phydev = to_phy_device(dev);
	struct net_device *netdev = phydev->attached_dev;
	int ret;

	if (!netdev)
	return 0;

	ret = phy_init_hw(phydev);
	if (ret < 0)
	return ret;

	/* The PHY needs to renegotiate. */
	phydev->link = 0;
	phydev->state = PHY_UP;

	phy_start_machine(phydev, NULL);

	return 0;
	}

	static struct dev_pm_ops mdio_bus_pm_ops = {
	.suspend = mdio_bus_suspend,
	.resume = mdio_bus_resume,
	.freeze = mdio_bus_suspend,
	.thaw = mdio_bus_resume,
	.restore = mdio_bus_restore,
	};

	#define MDIO_BUS_PM_OPS (&mdio_bus_pm_ops)

	#else

	#define MDIO_BUS_PM_OPS NULL

	#endif /* CONFIG_PM */

	static ssize_t
	phy_id_show(struct device dev, struct device_attribute attr, char *buf)
	{
	struct phy_device *phydev = to_phy_device(dev);

	return sprintf(buf, "0x%.8lx\n", (unsigned long)phydev->phy_id);
	}
	static DEVICE_ATTR_RO(phy_id);

	static struct attribute *mdio_dev_attrs[] = {
	&dev_attr_phy_id.attr,
	NULL,
	};
	ATTRIBUTE_GROUPS(mdio_dev);

	struct bus_type mdio_bus_type = {
	.name = "mdio_bus",
	.match = mdio_bus_match,
	.pm = MDIO_BUS_PM_OPS,
	.dev_groups = mdio_dev_groups,
	};
	EXPORT_SYMBOL(mdio_bus_type);

	int __init mdio_bus_init(void)
	{
	int ret;

	ret = class_register(&mdio_bus_class);
	if (!ret) {
	ret = bus_register(&mdio_bus_type);
	if (ret)
	class_unregister(&mdio_bus_class);
	}

	return ret;
	}

	void mdio_bus_exit(void)
	{
	class_unregister(&mdio_bus_class);
	bus_unregister(&mdio_bus_type);
	}