Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1422 insertions, 0 deletions

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
new file mode 100644
index 000000000..25dcaa49a
--- /dev/null
+++ b/drivers/net/phy/mdio_bus.c
@@ -0,0 +1,1422 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* MDIO Bus 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.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/micrel_phy.h>
+#include <linux/mii.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/reset.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/unistd.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/mdio.h>
+
+#include "mdio-boardinfo.h"
+
+static int mdiobus_register_gpiod(struct mdio_device *mdiodev)
+{
+	/* Deassert the optional reset signal */
+	mdiodev->reset_gpio = gpiod_get_optional(&mdiodev->dev,
+						 "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(mdiodev->reset_gpio))
+		return PTR_ERR(mdiodev->reset_gpio);
+
+	if (mdiodev->reset_gpio)
+		gpiod_set_consumer_name(mdiodev->reset_gpio, "PHY reset");
+
+	return 0;
+}
+
+static int mdiobus_register_reset(struct mdio_device *mdiodev)
+{
+	struct reset_control *reset;
+
+	reset = reset_control_get_optional_exclusive(&mdiodev->dev, "phy");
+	if (IS_ERR(reset))
+		return PTR_ERR(reset);
+
+	mdiodev->reset_ctrl = reset;
+
+	return 0;
+}
+
+int mdiobus_register_device(struct mdio_device *mdiodev)
+{
+	int err;
+
+	if (mdiodev->bus->mdio_map[mdiodev->addr])
+		return -EBUSY;
+
+	if (mdiodev->flags & MDIO_DEVICE_FLAG_PHY) {
+		err = mdiobus_register_gpiod(mdiodev);
+		if (err)
+			return err;
+
+		err = mdiobus_register_reset(mdiodev);
+		if (err)
+			return err;
+
+		/* Assert the reset signal */
+		mdio_device_reset(mdiodev, 1);
+	}
+
+	mdiodev->bus->mdio_map[mdiodev->addr] = mdiodev;
+
+	return 0;
+}
+EXPORT_SYMBOL(mdiobus_register_device);
+
+int mdiobus_unregister_device(struct mdio_device *mdiodev)
+{
+	if (mdiodev->bus->mdio_map[mdiodev->addr] != mdiodev)
+		return -EINVAL;
+
+	reset_control_put(mdiodev->reset_ctrl);
+
+	mdiodev->bus->mdio_map[mdiodev->addr] = NULL;
+
+	return 0;
+}
+EXPORT_SYMBOL(mdiobus_unregister_device);
+
+static struct mdio_device *mdiobus_find_device(struct mii_bus *bus, int addr)
+{
+	bool addr_valid = addr >= 0 && addr < ARRAY_SIZE(bus->mdio_map);
+
+	if (WARN_ONCE(!addr_valid, "addr %d out of range\n", addr))
+		return NULL;
+
+	return bus->mdio_map[addr];
+}
+
+struct phy_device *mdiobus_get_phy(struct mii_bus *bus, int addr)
+{
+	struct mdio_device *mdiodev;
+
+	mdiodev = mdiobus_find_device(bus, addr);
+	if (!mdiodev)
+		return NULL;
+
+	if (!(mdiodev->flags & MDIO_DEVICE_FLAG_PHY))
+		return NULL;
+
+	return container_of(mdiodev, struct phy_device, mdio);
+}
+EXPORT_SYMBOL(mdiobus_get_phy);
+
+bool mdiobus_is_registered_device(struct mii_bus *bus, int addr)
+{
+	return mdiobus_find_device(bus, addr) != NULL;
+}
+EXPORT_SYMBOL(mdiobus_is_registered_device);
+
+/**
+ * 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);
+
+/**
+ * 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);
+
+	WARN(bus->state != MDIOBUS_RELEASED &&
+	     /* for compatibility with error handling in drivers */
+	     bus->state != MDIOBUS_ALLOCATED,
+	     "%s: not in RELEASED or ALLOCATED state\n",
+	     bus->id);
+	kfree(bus);
+}
+
+struct mdio_bus_stat_attr {
+	int addr;
+	unsigned int field_offset;
+};
+
+static u64 mdio_bus_get_stat(struct mdio_bus_stats *s, unsigned int offset)
+{
+	const char *p = (const char *)s + offset;
+	unsigned int start;
+	u64 val = 0;
+
+	do {
+		start = u64_stats_fetch_begin(&s->syncp);
+		val = u64_stats_read((const u64_stats_t *)p);
+	} while (u64_stats_fetch_retry(&s->syncp, start));
+
+	return val;
+}
+
+static u64 mdio_bus_get_global_stat(struct mii_bus *bus, unsigned int offset)
+{
+	unsigned int i;
+	u64 val = 0;
+
+	for (i = 0; i < PHY_MAX_ADDR; i++)
+		val += mdio_bus_get_stat(&bus->stats[i], offset);
+
+	return val;
+}
+
+static ssize_t mdio_bus_stat_field_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct mii_bus *bus = to_mii_bus(dev);
+	struct mdio_bus_stat_attr *sattr;
+	struct dev_ext_attribute *eattr;
+	u64 val;
+
+	eattr = container_of(attr, struct dev_ext_attribute, attr);
+	sattr = eattr->var;
+
+	if (sattr->addr < 0)
+		val = mdio_bus_get_global_stat(bus, sattr->field_offset);
+	else
+		val = mdio_bus_get_stat(&bus->stats[sattr->addr],
+					sattr->field_offset);
+
+	return sysfs_emit(buf, "%llu\n", val);
+}
+
+static ssize_t mdio_bus_device_stat_field_show(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	struct mdio_device *mdiodev = to_mdio_device(dev);
+	struct mii_bus *bus = mdiodev->bus;
+	struct mdio_bus_stat_attr *sattr;
+	struct dev_ext_attribute *eattr;
+	int addr = mdiodev->addr;
+	u64 val;
+
+	eattr = container_of(attr, struct dev_ext_attribute, attr);
+	sattr = eattr->var;
+
+	val = mdio_bus_get_stat(&bus->stats[addr], sattr->field_offset);
+
+	return sysfs_emit(buf, "%llu\n", val);
+}
+
+#define MDIO_BUS_STATS_ATTR_DECL(field, file)				\
+static struct dev_ext_attribute dev_attr_mdio_bus_##field = {		\
+	.attr = { .attr = { .name = file, .mode = 0444 },		\
+		     .show = mdio_bus_stat_field_show,			\
+	},								\
+	.var = &((struct mdio_bus_stat_attr) {				\
+		-1, offsetof(struct mdio_bus_stats, field)		\
+	}),								\
+};									\
+static struct dev_ext_attribute dev_attr_mdio_bus_device_##field = {	\
+	.attr = { .attr = { .name = file, .mode = 0444 },		\
+		     .show = mdio_bus_device_stat_field_show,		\
+	},								\
+	.var = &((struct mdio_bus_stat_attr) {				\
+		-1, offsetof(struct mdio_bus_stats, field)		\
+	}),								\
+};
+
+#define MDIO_BUS_STATS_ATTR(field)					\
+	MDIO_BUS_STATS_ATTR_DECL(field, __stringify(field))
+
+MDIO_BUS_STATS_ATTR(transfers);
+MDIO_BUS_STATS_ATTR(errors);
+MDIO_BUS_STATS_ATTR(writes);
+MDIO_BUS_STATS_ATTR(reads);
+
+#define MDIO_BUS_STATS_ADDR_ATTR_DECL(field, addr, file)		\
+static struct dev_ext_attribute dev_attr_mdio_bus_addr_##field##_##addr = { \
+	.attr = { .attr = { .name = file, .mode = 0444 },		\
+		     .show = mdio_bus_stat_field_show,			\
+	},								\
+	.var = &((struct mdio_bus_stat_attr) {				\
+		addr, offsetof(struct mdio_bus_stats, field)		\
+	}),								\
+}
+
+#define MDIO_BUS_STATS_ADDR_ATTR(field, addr)				\
+	MDIO_BUS_STATS_ADDR_ATTR_DECL(field, addr,			\
+				 __stringify(field) "_" __stringify(addr))
+
+#define MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(addr)			\
+	MDIO_BUS_STATS_ADDR_ATTR(transfers, addr);			\
+	MDIO_BUS_STATS_ADDR_ATTR(errors, addr);				\
+	MDIO_BUS_STATS_ADDR_ATTR(writes, addr);				\
+	MDIO_BUS_STATS_ADDR_ATTR(reads, addr)				\
+
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(0);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(1);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(2);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(3);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(4);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(5);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(6);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(7);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(8);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(9);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(10);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(11);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(12);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(13);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(14);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(15);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(16);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(17);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(18);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(19);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(20);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(21);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(22);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(23);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(24);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(25);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(26);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(27);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(28);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(29);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(30);
+MDIO_BUS_STATS_ADDR_ATTR_GROUP_DECL(31);
+
+#define MDIO_BUS_STATS_ADDR_ATTR_GROUP(addr)				\
+	&dev_attr_mdio_bus_addr_transfers_##addr.attr.attr,		\
+	&dev_attr_mdio_bus_addr_errors_##addr.attr.attr,		\
+	&dev_attr_mdio_bus_addr_writes_##addr.attr.attr,		\
+	&dev_attr_mdio_bus_addr_reads_##addr.attr.attr			\
+
+static struct attribute *mdio_bus_statistics_attrs[] = {
+	&dev_attr_mdio_bus_transfers.attr.attr,
+	&dev_attr_mdio_bus_errors.attr.attr,
+	&dev_attr_mdio_bus_writes.attr.attr,
+	&dev_attr_mdio_bus_reads.attr.attr,
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(0),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(1),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(2),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(3),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(4),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(5),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(6),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(7),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(8),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(9),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(10),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(11),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(12),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(13),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(14),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(15),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(16),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(17),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(18),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(19),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(20),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(21),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(22),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(23),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(24),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(25),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(26),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(27),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(28),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(29),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(30),
+	MDIO_BUS_STATS_ADDR_ATTR_GROUP(31),
+	NULL,
+};
+
+static const struct attribute_group mdio_bus_statistics_group = {
+	.name	= "statistics",
+	.attrs	= mdio_bus_statistics_attrs,
+};
+
+static const struct attribute_group *mdio_bus_groups[] = {
+	&mdio_bus_statistics_group,
+	NULL,
+};
+
+static struct class mdio_bus_class = {
+	.name		= "mdio_bus",
+	.dev_release	= mdiobus_release,
+	.dev_groups	= mdio_bus_groups,
+};
+
+/**
+ * mdio_find_bus - Given the name of a mdiobus, find the mii_bus.
+ * @mdio_name: The name of a mdiobus.
+ *
+ * Returns a reference to the mii_bus, or NULL if none found.  The
+ * embedded struct device will have its reference count incremented,
+ * and this must be put_deviced'ed once the bus is finished with.
+ */
+struct mii_bus *mdio_find_bus(const char *mdio_name)
+{
+	struct device *d;
+
+	d = class_find_device_by_name(&mdio_bus_class, mdio_name);
+	return d ? to_mii_bus(d) : NULL;
+}
+EXPORT_SYMBOL(mdio_find_bus);
+
+#if IS_ENABLED(CONFIG_OF_MDIO)
+/**
+ * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
+ * @mdio_bus_np: Pointer to the mii_bus.
+ *
+ * Returns a reference to the mii_bus, or NULL if none found.  The
+ * embedded struct device will have its reference count incremented,
+ * and this must be put once the bus is finished with.
+ *
+ * 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_by_of_node(&mdio_bus_class, mdio_bus_np);
+	return d ? to_mii_bus(d) : NULL;
+}
+EXPORT_SYMBOL(of_mdio_find_bus);
+
+/* 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.
+ */
+static void of_mdiobus_link_mdiodev(struct mii_bus *bus,
+				    struct mdio_device *mdiodev)
+{
+	struct device *dev = &mdiodev->dev;
+	struct device_node *child;
+
+	if (dev->of_node || !bus->dev.of_node)
+		return;
+
+	for_each_available_child_of_node(bus->dev.of_node, child) {
+		int addr;
+
+		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;
+		}
+	}
+}
+#else /* !IS_ENABLED(CONFIG_OF_MDIO) */
+static inline void of_mdiobus_link_mdiodev(struct mii_bus *mdio,
+					   struct mdio_device *mdiodev)
+{
+}
+#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;
+
+	strncpy(mdiodev->modalias, bi->modalias,
+		sizeof(mdiodev->modalias));
+	mdiodev->bus_match = mdio_device_bus_match;
+	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);
+	int err;
+
+	phydev = get_phy_device(bus, addr, c45);
+	if (IS_ERR(phydev))
+		return phydev;
+
+	/* 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);
+
+	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);
+
+	/* 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;
+
+		if (mdiodev->reset_gpio)
+			gpiod_put(mdiodev->reset_gpio);
+
+		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);
+
+static void mdiobus_stats_acct(struct mdio_bus_stats *stats, bool op, int ret)
+{
+	preempt_disable();
+	u64_stats_update_begin(&stats->syncp);
+
+	u64_stats_inc(&stats->transfers);
+	if (ret < 0) {
+		u64_stats_inc(&stats->errors);
+		goto out;
+	}
+
+	if (op)
+		u64_stats_inc(&stats->reads);
+	else
+		u64_stats_inc(&stats->writes);
+out:
+	u64_stats_update_end(&stats->syncp);
+	preempt_enable();
+}
+
+/**
+ * __mdiobus_read - Unlocked version of the mdiobus_read function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to read
+ *
+ * Read a MDIO bus register. Caller must hold the mdio bus lock.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+int __mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
+{
+	int retval;
+
+	lockdep_assert_held_once(&bus->mdio_lock);
+
+	if (bus->read)
+		retval = bus->read(bus, addr, regnum);
+	else
+		retval = -EOPNOTSUPP;
+
+	trace_mdio_access(bus, 1, addr, regnum, retval, retval);
+	mdiobus_stats_acct(&bus->stats[addr], true, retval);
+
+	return retval;
+}
+EXPORT_SYMBOL(__mdiobus_read);
+
+/**
+ * __mdiobus_write - Unlocked version of the mdiobus_write function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @val: value to write to @regnum
+ *
+ * Write a MDIO bus register. Caller must hold the mdio bus lock.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+int __mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
+{
+	int err;
+
+	lockdep_assert_held_once(&bus->mdio_lock);
+
+	if (bus->write)
+		err = bus->write(bus, addr, regnum, val);
+	else
+		err = -EOPNOTSUPP;
+
+	trace_mdio_access(bus, 0, addr, regnum, val, err);
+	mdiobus_stats_acct(&bus->stats[addr], false, err);
+
+	return err;
+}
+EXPORT_SYMBOL(__mdiobus_write);
+
+/**
+ * __mdiobus_modify_changed - Unlocked version of the mdiobus_modify function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ *
+ * Read, modify, and if any change, write the register value back to the
+ * device. Any error returns a negative number.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+int __mdiobus_modify_changed(struct mii_bus *bus, int addr, u32 regnum,
+			     u16 mask, u16 set)
+{
+	int new, ret;
+
+	ret = __mdiobus_read(bus, addr, regnum);
+	if (ret < 0)
+		return ret;
+
+	new = (ret & ~mask) | set;
+	if (new == ret)
+		return 0;
+
+	ret = __mdiobus_write(bus, addr, regnum, new);
+
+	return ret < 0 ? ret : 1;
+}
+EXPORT_SYMBOL_GPL(__mdiobus_modify_changed);
+
+/**
+ * __mdiobus_c45_read - Unlocked version of the mdiobus_c45_read function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to read
+ *
+ * Read a MDIO bus register. Caller must hold the mdio bus lock.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+int __mdiobus_c45_read(struct mii_bus *bus, int addr, int devad, u32 regnum)
+{
+	int retval;
+
+	lockdep_assert_held_once(&bus->mdio_lock);
+
+	if (bus->read_c45)
+		retval = bus->read_c45(bus, addr, devad, regnum);
+	else
+		retval = -EOPNOTSUPP;
+
+	trace_mdio_access(bus, 1, addr, regnum, retval, retval);
+	mdiobus_stats_acct(&bus->stats[addr], true, retval);
+
+	return retval;
+}
+EXPORT_SYMBOL(__mdiobus_c45_read);
+
+/**
+ * __mdiobus_c45_write - Unlocked version of the mdiobus_write function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to write
+ * @val: value to write to @regnum
+ *
+ * Write a MDIO bus register. Caller must hold the mdio bus lock.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+int __mdiobus_c45_write(struct mii_bus *bus, int addr, int devad, u32 regnum,
+			u16 val)
+{
+	int err;
+
+	lockdep_assert_held_once(&bus->mdio_lock);
+
+	if (bus->write_c45)
+		err = bus->write_c45(bus, addr, devad, regnum, val);
+	else
+		err = -EOPNOTSUPP;
+
+	trace_mdio_access(bus, 0, addr, regnum, val, err);
+	mdiobus_stats_acct(&bus->stats[addr], false, err);
+
+	return err;
+}
+EXPORT_SYMBOL(__mdiobus_c45_write);
+
+/**
+ * __mdiobus_c45_modify_changed - Unlocked version of the mdiobus_modify function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ *
+ * Read, modify, and if any change, write the register value back to the
+ * device. Any error returns a negative number.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+static int __mdiobus_c45_modify_changed(struct mii_bus *bus, int addr,
+					int devad, u32 regnum, u16 mask,
+					u16 set)
+{
+	int new, ret;
+
+	ret = __mdiobus_c45_read(bus, addr, devad, regnum);
+	if (ret < 0)
+		return ret;
+
+	new = (ret & ~mask) | set;
+	if (new == ret)
+		return 0;
+
+	ret = __mdiobus_c45_write(bus, addr, devad, regnum, new);
+
+	return ret < 0 ? ret : 1;
+}
+
+/**
+ * mdiobus_read_nested - Nested version of the mdiobus_read function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to read
+ *
+ * In case of nested MDIO bus access avoid lockdep false positives by
+ * using mutex_lock_nested().
+ *
+ * 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_nested(struct mii_bus *bus, int addr, u32 regnum)
+{
+	int retval;
+
+	mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
+	retval = __mdiobus_read(bus, addr, regnum);
+	mutex_unlock(&bus->mdio_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL(mdiobus_read_nested);
+
+/**
+ * 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;
+
+	mutex_lock(&bus->mdio_lock);
+	retval = __mdiobus_read(bus, addr, regnum);
+	mutex_unlock(&bus->mdio_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL(mdiobus_read);
+
+/**
+ * mdiobus_c45_read - Convenience function for reading a given MII mgmt register
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @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_c45_read(struct mii_bus *bus, int addr, int devad, u32 regnum)
+{
+	int retval;
+
+	mutex_lock(&bus->mdio_lock);
+	retval = __mdiobus_c45_read(bus, addr, devad, regnum);
+	mutex_unlock(&bus->mdio_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL(mdiobus_c45_read);
+
+/**
+ * mdiobus_c45_read_nested - Nested version of the mdiobus_c45_read function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to read
+ *
+ * In case of nested MDIO bus access avoid lockdep false positives by
+ * using mutex_lock_nested().
+ *
+ * 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_c45_read_nested(struct mii_bus *bus, int addr, int devad,
+			    u32 regnum)
+{
+	int retval;
+
+	mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
+	retval = __mdiobus_c45_read(bus, addr, devad, regnum);
+	mutex_unlock(&bus->mdio_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL(mdiobus_c45_read_nested);
+
+/**
+ * mdiobus_write_nested - Nested version of the mdiobus_write function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @val: value to write to @regnum
+ *
+ * In case of nested MDIO bus access avoid lockdep false positives by
+ * using mutex_lock_nested().
+ *
+ * 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_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val)
+{
+	int err;
+
+	mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
+	err = __mdiobus_write(bus, addr, regnum, val);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(mdiobus_write_nested);
+
+/**
+ * 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;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_write(bus, addr, regnum, val);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(mdiobus_write);
+
+/**
+ * mdiobus_c45_write - Convenience function for writing a given MII mgmt register
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @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_c45_write(struct mii_bus *bus, int addr, int devad, u32 regnum,
+		      u16 val)
+{
+	int err;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_c45_write(bus, addr, devad, regnum, val);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(mdiobus_c45_write);
+
+/**
+ * mdiobus_c45_write_nested - Nested version of the mdiobus_c45_write function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to write
+ * @val: value to write to @regnum
+ *
+ * In case of nested MDIO bus access avoid lockdep false positives by
+ * using mutex_lock_nested().
+ *
+ * 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_c45_write_nested(struct mii_bus *bus, int addr, int devad,
+			     u32 regnum, u16 val)
+{
+	int err;
+
+	mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
+	err = __mdiobus_c45_write(bus, addr, devad, regnum, val);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(mdiobus_c45_write_nested);
+
+/*
+ * __mdiobus_modify - Convenience function for modifying a given mdio device
+ *	register
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int __mdiobus_modify(struct mii_bus *bus, int addr, u32 regnum, u16 mask,
+		     u16 set)
+{
+	int err;
+
+	err = __mdiobus_modify_changed(bus, addr, regnum, mask, set);
+
+	return err < 0 ? err : 0;
+}
+EXPORT_SYMBOL_GPL(__mdiobus_modify);
+
+/**
+ * mdiobus_modify - Convenience function for modifying a given mdio device
+ *	register
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int mdiobus_modify(struct mii_bus *bus, int addr, u32 regnum, u16 mask, u16 set)
+{
+	int err;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_modify(bus, addr, regnum, mask, set);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(mdiobus_modify);
+
+/**
+ * mdiobus_c45_modify - Convenience function for modifying a given mdio device
+ *	register
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int mdiobus_c45_modify(struct mii_bus *bus, int addr, int devad, u32 regnum,
+		       u16 mask, u16 set)
+{
+	int err;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_c45_modify_changed(bus, addr, devad, regnum,
+					   mask, set);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err < 0 ? err : 0;
+}
+EXPORT_SYMBOL_GPL(mdiobus_c45_modify);
+
+/**
+ * mdiobus_modify_changed - Convenience function for modifying a given mdio
+ *	device register and returning if it changed
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int mdiobus_modify_changed(struct mii_bus *bus, int addr, u32 regnum,
+			   u16 mask, u16 set)
+{
+	int err;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_modify_changed(bus, addr, regnum, mask, set);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(mdiobus_modify_changed);
+
+/**
+ * mdiobus_c45_modify_changed - Convenience function for modifying a given mdio
+ *	device register and returning if it changed
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @devad: device address to read
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int mdiobus_c45_modify_changed(struct mii_bus *bus, int addr, int devad,
+			       u32 regnum, u16 mask, u16 set)
+{
+	int err;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_c45_modify_changed(bus, addr, devad, regnum, mask, set);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(mdiobus_c45_modify_changed);
+
+/**
+ * mdio_bus_match - determine if given MDIO driver supports the given
+ *		    MDIO device
+ * @dev: target MDIO device
+ * @drv: given MDIO driver
+ *
+ * Description: Given a MDIO device, and a MDIO driver, return 1 if
+ *   the driver supports the device.  Otherwise, return 0. This may
+ *   require calling the devices own match function, since different classes
+ *   of MDIO devices have different match criteria.
+ */
+static int mdio_bus_match(struct device *dev, struct device_driver *drv)
+{
+	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
+	struct mdio_device *mdio = to_mdio_device(dev);
+
+	/* Both the driver and device must type-match */
+	if (!(mdiodrv->mdiodrv.flags & MDIO_DEVICE_IS_PHY) !=
+	    !(mdio->flags & MDIO_DEVICE_FLAG_PHY))
+		return 0;
+
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
+	if (mdio->bus_match)
+		return mdio->bus_match(dev, drv);
+
+	return 0;
+}
+
+static int mdio_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	int rc;
+
+	/* Some devices have extra OF data and an OF-style MODALIAS */
+	rc = of_device_uevent_modalias(dev, env);
+	if (rc != -ENODEV)
+		return rc;
+
+	return 0;
+}
+
+static struct attribute *mdio_bus_device_statistics_attrs[] = {
+	&dev_attr_mdio_bus_device_transfers.attr.attr,
+	&dev_attr_mdio_bus_device_errors.attr.attr,
+	&dev_attr_mdio_bus_device_writes.attr.attr,
+	&dev_attr_mdio_bus_device_reads.attr.attr,
+	NULL,
+};
+
+static const struct attribute_group mdio_bus_device_statistics_group = {
+	.name	= "statistics",
+	.attrs	= mdio_bus_device_statistics_attrs,
+};
+
+static const struct attribute_group *mdio_bus_dev_groups[] = {
+	&mdio_bus_device_statistics_group,
+	NULL,
+};
+
+struct bus_type mdio_bus_type = {
+	.name		= "mdio_bus",
+	.dev_groups	= mdio_bus_dev_groups,
+	.match		= mdio_bus_match,
+	.uevent		= mdio_uevent,
+};
+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;
+}
+
+#if IS_ENABLED(CONFIG_PHYLIB)
+void mdio_bus_exit(void)
+{
+	class_unregister(&mdio_bus_class);
+	bus_unregister(&mdio_bus_type);
+}
+EXPORT_SYMBOL_GPL(mdio_bus_exit);
+#else
+module_init(mdio_bus_init);
+/* no module_exit, intentional */
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MDIO bus/device layer");
+#endif