drivers/net/phy/mdio_bus_provider.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /* MDIO Bus provider interface
  *
  * Author: Andy Fleming
  *
  * Copyright (c) 2004 Freescale Semiconductor, Inc.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/micrel_phy.h>
 #include <linux/mii.h>
 #include <linux/mm.h>
 #include <linux/netdevice.h>
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
 #include <linux/phy.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/uaccess.h>
 #include <linux/unistd.h>

 #include "mdio-boardinfo.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;
 	int i;

 	/* 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)
 		return NULL;

 	bus->state = MDIOBUS_ALLOCATED;
 	if (size)
 		bus->priv = (void *)bus + aligned_size;

 	/* Initialise the interrupts to polling and 64-bit seqcounts */
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		bus->irq[i] = PHY_POLL;
 		u64_stats_init(&bus->stats[i].syncp);
 	}

 	return bus;
 }
 EXPORT_SYMBOL(mdiobus_alloc_size);

 #if IS_ENABLED(CONFIG_OF_MDIO)
 /* Walk the list of subnodes of a mdio bus and look for a node that
  * matches the mdio device's address with its 'reg' property. If
  * found, set the of_node pointer for the mdio device. This allows
  * auto-probed phy devices to be supplied with information passed in
  * via DT.
  * If a PHY package is found, PHY is searched also there.
  */
 static int of_mdiobus_find_phy(struct device *dev, struct mdio_device *mdiodev,
 			       struct device_node *np)
 {
 	struct device_node *child;

 	for_each_available_child_of_node(np, child) {
 		int addr;

 		if (of_node_name_eq(child, "ethernet-phy-package")) {
 			/* Validate PHY package reg presence */
 			if (!of_property_present(child, "reg")) {
 				of_node_put(child);
 				return -EINVAL;
 			}

 			if (!of_mdiobus_find_phy(dev, mdiodev, child)) {
 				/* The refcount for the PHY package will be
 				 * incremented later when PHY join the Package.
 				 */
 				of_node_put(child);
 				return 0;
 			}

 			continue;
 		}

 		addr = of_mdio_parse_addr(dev, child);
 		if (addr < 0)
 			continue;

 		if (addr == mdiodev->addr) {
 			device_set_node(dev, of_fwnode_handle(child));
 			/* The refcount on "child" is passed to the mdio
 			 * device. Do _not_ use of_node_put(child) here.
 			 */
 			return 0;
 		}
 	}

 	return -ENODEV;
 }

 static void of_mdiobus_link_mdiodev(struct mii_bus *bus,
 				    struct mdio_device *mdiodev)
 {
 	struct device *dev = &mdiodev->dev;

 	if (dev->of_node || !bus->dev.of_node)
 		return;

 	of_mdiobus_find_phy(dev, mdiodev, bus->dev.of_node);
 }
 #endif

 /**
  * mdiobus_create_device - create a full MDIO device given
  * a mdio_board_info structure
  * @bus: MDIO bus to create the devices on
  * @bi: mdio_board_info structure describing the devices
  *
  * Returns 0 on success or < 0 on error.
  */
 static int mdiobus_create_device(struct mii_bus *bus,
 				 struct mdio_board_info *bi)
 {
 	struct mdio_device *mdiodev;
 	int ret = 0;

 	mdiodev = mdio_device_create(bus, bi->mdio_addr);
 	if (IS_ERR(mdiodev))
 		return -ENODEV;

 	strscpy(mdiodev->modalias, bi->modalias,
 		sizeof(mdiodev->modalias));
 	mdiodev->dev.platform_data = (void *)bi->platform_data;

 	ret = mdio_device_register(mdiodev);
 	if (ret)
 		mdio_device_free(mdiodev);

 	return ret;
 }

 static struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr, bool c45)
 {
 	struct phy_device *phydev = ERR_PTR(-ENODEV);
 	struct fwnode_handle *fwnode;
 	char node_name[16];
 	int err;

 	phydev = get_phy_device(bus, addr, c45);
 	if (IS_ERR(phydev))
 		return phydev;

 #if IS_ENABLED(CONFIG_OF_MDIO)
 	/* For DT, see if the auto-probed phy has a corresponding child
 	 * in the bus node, and set the of_node pointer in this case.
 	 */
 	of_mdiobus_link_mdiodev(bus, &phydev->mdio);
 #endif

 	/* Search for a swnode for the phy in the swnode hierarchy of the bus.
 	 * If there is no swnode for the phy provided, just ignore it.
 	 */
 	if (dev_fwnode(&bus->dev) && !dev_fwnode(&phydev->mdio.dev)) {
 		snprintf(node_name, sizeof(node_name), "ethernet-phy@%d",
 			 addr);
 		fwnode = fwnode_get_named_child_node(dev_fwnode(&bus->dev),
 						     node_name);
 		if (fwnode)
 			device_set_node(&phydev->mdio.dev, fwnode);
 	}

 	err = phy_device_register(phydev);
 	if (err) {
 		phy_device_free(phydev);
 		return ERR_PTR(-ENODEV);
 	}

 	return phydev;
 }

 /**
  * mdiobus_scan_c22 - scan one address on a bus for C22 MDIO devices.
  * @bus: mii_bus to scan
  * @addr: address on bus to scan
  *
  * This function scans one address on the MDIO bus, looking for
  * devices which can be identified using a vendor/product ID in
  * registers 2 and 3. Not all MDIO devices have such registers, but
  * PHY devices typically do. Hence this function assumes anything
  * found is a PHY, or can be treated as a PHY. Other MDIO devices,
  * such as switches, will probably not be found during the scan.
  */
 struct phy_device *mdiobus_scan_c22(struct mii_bus *bus, int addr)
 {
 	return mdiobus_scan(bus, addr, false);
 }
 EXPORT_SYMBOL(mdiobus_scan_c22);

 /**
  * mdiobus_scan_c45 - scan one address on a bus for C45 MDIO devices.
  * @bus: mii_bus to scan
  * @addr: address on bus to scan
  *
  * This function scans one address on the MDIO bus, looking for
  * devices which can be identified using a vendor/product ID in
  * registers 2 and 3. Not all MDIO devices have such registers, but
  * PHY devices typically do. Hence this function assumes anything
  * found is a PHY, or can be treated as a PHY. Other MDIO devices,
  * such as switches, will probably not be found during the scan.
  */
 static struct phy_device *mdiobus_scan_c45(struct mii_bus *bus, int addr)
 {
 	return mdiobus_scan(bus, addr, true);
 }

 static int mdiobus_scan_bus_c22(struct mii_bus *bus)
 {
 	int i;

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

 			phydev = mdiobus_scan_c22(bus, i);
 			if (IS_ERR(phydev) && (PTR_ERR(phydev) != -ENODEV))
 				return PTR_ERR(phydev);
 		}
 	}
 	return 0;
 }

 static int mdiobus_scan_bus_c45(struct mii_bus *bus)
 {
 	int i;

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

 			/* Don't scan C45 if we already have a C22 device */
 			if (bus->mdio_map[i])
 				continue;

 			phydev = mdiobus_scan_c45(bus, i);
 			if (IS_ERR(phydev) && (PTR_ERR(phydev) != -ENODEV))
 				return PTR_ERR(phydev);
 		}
 	}
 	return 0;
 }

 /* There are some C22 PHYs which do bad things when where is a C45
  * transaction on the bus, like accepting a read themselves, and
  * stomping over the true devices reply, to performing a write to
  * themselves which was intended for another device. Now that C22
  * devices have been found, see if any of them are bad for C45, and if we
  * should skip the C45 scan.
  */
 static bool mdiobus_prevent_c45_scan(struct mii_bus *bus)
 {
 	int i;

 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		struct phy_device *phydev;
 		u32 oui;

 		phydev = mdiobus_get_phy(bus, i);
 		if (!phydev)
 			continue;
 		oui = phydev->phy_id >> 10;

 		if (oui == MICREL_OUI)
 			return true;
 	}
 	return false;
 }

 /**
  * __mdiobus_register - bring up all the PHYs on a given bus and attach them to bus
  * @bus: target mii_bus
  * @owner: module containing bus accessor functions
  *
  * Description: Called by a bus driver to bring up all the PHYs
  *   on a given bus, and attach them to the bus. Drivers should use
  *   mdiobus_register() rather than __mdiobus_register() unless they
  *   need to pass a specific owner module. MDIO devices which are not
  *   PHYs will not be brought up by this function. They are expected
  *   to be explicitly listed in DT and instantiated by of_mdiobus_register().
  *
  * Returns 0 on success or < 0 on error.
  */
 int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 {
 	struct mdio_device *mdiodev;
 	struct gpio_desc *gpiod;
 	bool prevent_c45_scan;
 	int i, err;

 	if (!bus || !bus->name)
 		return -EINVAL;

 	/* An access method always needs both read and write operations */
 	if (!!bus->read != !!bus->write || !!bus->read_c45 != !!bus->write_c45)
 		return -EINVAL;

 	/* At least one method is mandatory */
 	if (!bus->read && !bus->read_c45)
 		return -EINVAL;

 	if (bus->parent && bus->parent->of_node)
 		bus->parent->of_node->fwnode.flags |=
 					FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD;

 	WARN(bus->state != MDIOBUS_ALLOCATED &&
 	     bus->state != MDIOBUS_UNREGISTERED,
 	     "%s: not in ALLOCATED or UNREGISTERED state\n", bus->id);

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

 	/* If the bus state is allocated, we're registering a fresh bus
 	 * that may have a fwnode associated with it. Grab a reference
 	 * to the fwnode. This will be dropped when the bus is released.
 	 * If the bus was set to unregistered, it means that the bus was
 	 * previously registered, and we've already grabbed a reference.
 	 */
 	if (bus->state == MDIOBUS_ALLOCATED)
 		fwnode_handle_get(dev_fwnode(&bus->dev));

 	/* We need to set state to MDIOBUS_UNREGISTERED to correctly release
 	 * the device in mdiobus_free()
 	 *
 	 * State will be updated later in this function in case of success
 	 */
 	bus->state = MDIOBUS_UNREGISTERED;

 	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);
 	mutex_init(&bus->shared_lock);

 	/* assert bus level PHY GPIO reset */
 	gpiod = devm_gpiod_get_optional(&bus->dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(gpiod)) {
 		err = dev_err_probe(&bus->dev, PTR_ERR(gpiod),
 				    "mii_bus %s couldn't get reset GPIO\n",
 				    bus->id);
 		device_del(&bus->dev);
 		return err;
 	} else	if (gpiod) {
 		bus->reset_gpiod = gpiod;
 		fsleep(bus->reset_delay_us);
 		gpiod_set_value_cansleep(gpiod, 0);
 		if (bus->reset_post_delay_us > 0)
 			fsleep(bus->reset_post_delay_us);
 	}

 	if (bus->reset) {
 		err = bus->reset(bus);
 		if (err)
 			goto error_reset_gpiod;
 	}

 	if (bus->read) {
 		err = mdiobus_scan_bus_c22(bus);
 		if (err)
 			goto error;
 	}

 	prevent_c45_scan = mdiobus_prevent_c45_scan(bus);

 	if (!prevent_c45_scan && bus->read_c45) {
 		err = mdiobus_scan_bus_c45(bus);
 		if (err)
 			goto error;
 	}

 	mdiobus_setup_mdiodev_from_board_info(bus, mdiobus_create_device);

 	bus->state = MDIOBUS_REGISTERED;
 	dev_dbg(&bus->dev, "probed\n");
 	return 0;

 error:
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		mdiodev = bus->mdio_map[i];
 		if (!mdiodev)
 			continue;

 		mdiodev->device_remove(mdiodev);
 		mdiodev->device_free(mdiodev);
 	}
 error_reset_gpiod:
 	/* Put PHYs in RESET to save power */
 	if (bus->reset_gpiod)
 		gpiod_set_value_cansleep(bus->reset_gpiod, 1);

 	device_del(&bus->dev);
 	return err;
 }
 EXPORT_SYMBOL(__mdiobus_register);

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

 	if (WARN_ON_ONCE(bus->state != MDIOBUS_REGISTERED))
 		return;
 	bus->state = MDIOBUS_UNREGISTERED;

 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		mdiodev = bus->mdio_map[i];
 		if (!mdiodev)
 			continue;

 		mdiodev->device_remove(mdiodev);
 		mdiodev->device_free(mdiodev);
 	}

 	/* Put PHYs in RESET to save power */
 	if (bus->reset_gpiod)
 		gpiod_set_value_cansleep(bus->reset_gpiod, 1);

 	device_del(&bus->dev);
 }
 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;
 	}

 	WARN(bus->state != MDIOBUS_UNREGISTERED,
 	     "%s: not in UNREGISTERED state\n", bus->id);
 	bus->state = MDIOBUS_RELEASED;

 	put_device(&bus->dev);
 }
 EXPORT_SYMBOL(mdiobus_free);
	// SPDX-License-Identifier: GPL-2.0+
	/* MDIO Bus provider interface
	*
	* Author: Andy Fleming
	*
	* Copyright (c) 2004 Freescale Semiconductor, Inc.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/errno.h>
	#include <linux/etherdevice.h>
	#include <linux/ethtool.h>
	#include <linux/gpio/consumer.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/micrel_phy.h>
	#include <linux/mii.h>
	#include <linux/mm.h>
	#include <linux/netdevice.h>
	#include <linux/of_device.h>
	#include <linux/of_mdio.h>
	#include <linux/phy.h>
	#include <linux/slab.h>
	#include <linux/string.h>
	#include <linux/uaccess.h>
	#include <linux/unistd.h>

	#include "mdio-boardinfo.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;
	int i;

	/* 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)
	return NULL;

	bus->state = MDIOBUS_ALLOCATED;
	if (size)
	bus->priv = (void *)bus + aligned_size;

	/* Initialise the interrupts to polling and 64-bit seqcounts */
	for (i = 0; i < PHY_MAX_ADDR; i++) {
	bus->irq[i] = PHY_POLL;
	u64_stats_init(&bus->stats[i].syncp);
	}

	return bus;
	}
	EXPORT_SYMBOL(mdiobus_alloc_size);

	#if IS_ENABLED(CONFIG_OF_MDIO)
	/* Walk the list of subnodes of a mdio bus and look for a node that
	* matches the mdio device's address with its 'reg' property. If
	* found, set the of_node pointer for the mdio device. This allows
	* auto-probed phy devices to be supplied with information passed in
	* via DT.
	* If a PHY package is found, PHY is searched also there.
	*/
	static int of_mdiobus_find_phy(struct device dev, struct mdio_device mdiodev,
	struct device_node *np)
	{
	struct device_node *child;

	for_each_available_child_of_node(np, child) {
	int addr;

	if (of_node_name_eq(child, "ethernet-phy-package")) {
	/* Validate PHY package reg presence */
	if (!of_property_present(child, "reg")) {
	of_node_put(child);
	return -EINVAL;
	}

	if (!of_mdiobus_find_phy(dev, mdiodev, child)) {
	/* The refcount for the PHY package will be
	* incremented later when PHY join the Package.
	*/
	of_node_put(child);
	return 0;
	}

	continue;
	}

	addr = of_mdio_parse_addr(dev, child);
	if (addr < 0)
	continue;

	if (addr == mdiodev->addr) {
	device_set_node(dev, of_fwnode_handle(child));
	/* The refcount on "child" is passed to the mdio
	* device. Do _not_ use of_node_put(child) here.
	*/
	return 0;
	}
	}

	return -ENODEV;
	}

	static void of_mdiobus_link_mdiodev(struct mii_bus *bus,
	struct mdio_device *mdiodev)
	{
	struct device *dev = &mdiodev->dev;

	if (dev->of_node \|\| !bus->dev.of_node)
	return;

	of_mdiobus_find_phy(dev, mdiodev, bus->dev.of_node);
	}
	#endif

	/**
	* mdiobus_create_device - create a full MDIO device given
	* a mdio_board_info structure
	* @bus: MDIO bus to create the devices on
	* @bi: mdio_board_info structure describing the devices
	*
	* Returns 0 on success or < 0 on error.
	*/
	static int mdiobus_create_device(struct mii_bus *bus,
	struct mdio_board_info *bi)
	{
	struct mdio_device *mdiodev;
	int ret = 0;

	mdiodev = mdio_device_create(bus, bi->mdio_addr);
	if (IS_ERR(mdiodev))
	return -ENODEV;

	strscpy(mdiodev->modalias, bi->modalias,
	sizeof(mdiodev->modalias));
	mdiodev->dev.platform_data = (void *)bi->platform_data;

	ret = mdio_device_register(mdiodev);
	if (ret)
	mdio_device_free(mdiodev);

	return ret;
	}

	static struct phy_device mdiobus_scan(struct mii_bus bus, int addr, bool c45)
	{
	struct phy_device *phydev = ERR_PTR(-ENODEV);
	struct fwnode_handle *fwnode;
	char node_name[16];
	int err;

	phydev = get_phy_device(bus, addr, c45);
	if (IS_ERR(phydev))
	return phydev;

	#if IS_ENABLED(CONFIG_OF_MDIO)
	/* For DT, see if the auto-probed phy has a corresponding child
	* in the bus node, and set the of_node pointer in this case.
	*/
	of_mdiobus_link_mdiodev(bus, &phydev->mdio);
	#endif

	/* Search for a swnode for the phy in the swnode hierarchy of the bus.
	* If there is no swnode for the phy provided, just ignore it.
	*/
	if (dev_fwnode(&bus->dev) && !dev_fwnode(&phydev->mdio.dev)) {
	snprintf(node_name, sizeof(node_name), "ethernet-phy@%d",
	addr);
	fwnode = fwnode_get_named_child_node(dev_fwnode(&bus->dev),
	node_name);
	if (fwnode)
	device_set_node(&phydev->mdio.dev, fwnode);
	}

	err = phy_device_register(phydev);
	if (err) {
	phy_device_free(phydev);
	return ERR_PTR(-ENODEV);
	}

	return phydev;
	}

	/**
	* mdiobus_scan_c22 - scan one address on a bus for C22 MDIO devices.
	* @bus: mii_bus to scan
	* @addr: address on bus to scan
	*
	* This function scans one address on the MDIO bus, looking for
	* devices which can be identified using a vendor/product ID in
	* registers 2 and 3. Not all MDIO devices have such registers, but
	* PHY devices typically do. Hence this function assumes anything
	* found is a PHY, or can be treated as a PHY. Other MDIO devices,
	* such as switches, will probably not be found during the scan.
	*/
	struct phy_device mdiobus_scan_c22(struct mii_bus bus, int addr)
	{
	return mdiobus_scan(bus, addr, false);
	}
	EXPORT_SYMBOL(mdiobus_scan_c22);

	/**
	* mdiobus_scan_c45 - scan one address on a bus for C45 MDIO devices.
	* @bus: mii_bus to scan
	* @addr: address on bus to scan
	*
	* This function scans one address on the MDIO bus, looking for
	* devices which can be identified using a vendor/product ID in
	* registers 2 and 3. Not all MDIO devices have such registers, but
	* PHY devices typically do. Hence this function assumes anything
	* found is a PHY, or can be treated as a PHY. Other MDIO devices,
	* such as switches, will probably not be found during the scan.
	*/
	static struct phy_device mdiobus_scan_c45(struct mii_bus bus, int addr)
	{
	return mdiobus_scan(bus, addr, true);
	}

	static int mdiobus_scan_bus_c22(struct mii_bus *bus)
	{
	int i;

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

	phydev = mdiobus_scan_c22(bus, i);
	if (IS_ERR(phydev) && (PTR_ERR(phydev) != -ENODEV))
	return PTR_ERR(phydev);
	}
	}
	return 0;
	}

	static int mdiobus_scan_bus_c45(struct mii_bus *bus)
	{
	int i;

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

	/* Don't scan C45 if we already have a C22 device */
	if (bus->mdio_map[i])
	continue;

	phydev = mdiobus_scan_c45(bus, i);
	if (IS_ERR(phydev) && (PTR_ERR(phydev) != -ENODEV))
	return PTR_ERR(phydev);
	}
	}
	return 0;
	}

	/* There are some C22 PHYs which do bad things when where is a C45
	* transaction on the bus, like accepting a read themselves, and
	* stomping over the true devices reply, to performing a write to
	* themselves which was intended for another device. Now that C22
	* devices have been found, see if any of them are bad for C45, and if we
	* should skip the C45 scan.
	*/
	static bool mdiobus_prevent_c45_scan(struct mii_bus *bus)
	{
	int i;

	for (i = 0; i < PHY_MAX_ADDR; i++) {
	struct phy_device *phydev;
	u32 oui;

	phydev = mdiobus_get_phy(bus, i);
	if (!phydev)
	continue;
	oui = phydev->phy_id >> 10;

	if (oui == MICREL_OUI)
	return true;
	}
	return false;
	}

	/**
	* __mdiobus_register - bring up all the PHYs on a given bus and attach them to bus
	* @bus: target mii_bus
	* @owner: module containing bus accessor functions
	*
	* Description: Called by a bus driver to bring up all the PHYs
	* on a given bus, and attach them to the bus. Drivers should use
	* mdiobus_register() rather than __mdiobus_register() unless they
	* need to pass a specific owner module. MDIO devices which are not
	* PHYs will not be brought up by this function. They are expected
	* to be explicitly listed in DT and instantiated by of_mdiobus_register().
	*
	* Returns 0 on success or < 0 on error.
	*/
	int __mdiobus_register(struct mii_bus bus, struct module owner)
	{
	struct mdio_device *mdiodev;
	struct gpio_desc *gpiod;
	bool prevent_c45_scan;
	int i, err;

	if (!bus \|\| !bus->name)
	return -EINVAL;

	/* An access method always needs both read and write operations */
	if (!!bus->read != !!bus->write \|\| !!bus->read_c45 != !!bus->write_c45)
	return -EINVAL;

	/* At least one method is mandatory */
	if (!bus->read && !bus->read_c45)
	return -EINVAL;

	if (bus->parent && bus->parent->of_node)
	bus->parent->of_node->fwnode.flags \|=
	FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD;

	WARN(bus->state != MDIOBUS_ALLOCATED &&
	bus->state != MDIOBUS_UNREGISTERED,
	"%s: not in ALLOCATED or UNREGISTERED state\n", bus->id);

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

	/* If the bus state is allocated, we're registering a fresh bus
	* that may have a fwnode associated with it. Grab a reference
	* to the fwnode. This will be dropped when the bus is released.
	* If the bus was set to unregistered, it means that the bus was
	* previously registered, and we've already grabbed a reference.
	*/
	if (bus->state == MDIOBUS_ALLOCATED)
	fwnode_handle_get(dev_fwnode(&bus->dev));

	/* We need to set state to MDIOBUS_UNREGISTERED to correctly release
	* the device in mdiobus_free()
	*
	* State will be updated later in this function in case of success
	*/
	bus->state = MDIOBUS_UNREGISTERED;

	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);
	mutex_init(&bus->shared_lock);

	/* assert bus level PHY GPIO reset */
	gpiod = devm_gpiod_get_optional(&bus->dev, "reset", GPIOD_OUT_HIGH);
	if (IS_ERR(gpiod)) {
	err = dev_err_probe(&bus->dev, PTR_ERR(gpiod),
	"mii_bus %s couldn't get reset GPIO\n",
	bus->id);
	device_del(&bus->dev);
	return err;
	} else if (gpiod) {
	bus->reset_gpiod = gpiod;
	fsleep(bus->reset_delay_us);
	gpiod_set_value_cansleep(gpiod, 0);
	if (bus->reset_post_delay_us > 0)
	fsleep(bus->reset_post_delay_us);
	}

	if (bus->reset) {
	err = bus->reset(bus);
	if (err)
	goto error_reset_gpiod;
	}

	if (bus->read) {
	err = mdiobus_scan_bus_c22(bus);
	if (err)
	goto error;
	}

	prevent_c45_scan = mdiobus_prevent_c45_scan(bus);

	if (!prevent_c45_scan && bus->read_c45) {
	err = mdiobus_scan_bus_c45(bus);
	if (err)
	goto error;
	}

	mdiobus_setup_mdiodev_from_board_info(bus, mdiobus_create_device);

	bus->state = MDIOBUS_REGISTERED;
	dev_dbg(&bus->dev, "probed\n");
	return 0;

	error:
	for (i = 0; i < PHY_MAX_ADDR; i++) {
	mdiodev = bus->mdio_map[i];
	if (!mdiodev)
	continue;

	mdiodev->device_remove(mdiodev);
	mdiodev->device_free(mdiodev);
	}
	error_reset_gpiod:
	/* Put PHYs in RESET to save power */
	if (bus->reset_gpiod)
	gpiod_set_value_cansleep(bus->reset_gpiod, 1);

	device_del(&bus->dev);
	return err;
	}
	EXPORT_SYMBOL(__mdiobus_register);

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

	if (WARN_ON_ONCE(bus->state != MDIOBUS_REGISTERED))
	return;
	bus->state = MDIOBUS_UNREGISTERED;

	for (i = 0; i < PHY_MAX_ADDR; i++) {
	mdiodev = bus->mdio_map[i];
	if (!mdiodev)
	continue;

	mdiodev->device_remove(mdiodev);
	mdiodev->device_free(mdiodev);
	}

	/* Put PHYs in RESET to save power */
	if (bus->reset_gpiod)
	gpiod_set_value_cansleep(bus->reset_gpiod, 1);

	device_del(&bus->dev);
	}
	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;
	}

	WARN(bus->state != MDIOBUS_UNREGISTERED,
	"%s: not in UNREGISTERED state\n", bus->id);
	bus->state = MDIOBUS_RELEASED;

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