/* 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 <linux/io.h>
  #include <linux/uaccess.h>
  
  #include <asm/irq.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);
  
  static void _devm_mdiobus_free(struct device *dev, void *res)
  {
  	mdiobus_free(*(struct mii_bus **)res);
  }
  
  static int devm_mdiobus_match(struct device *dev, void *res, void *data)
  {
  	struct mii_bus **r = res;
  
  	if (WARN_ON(!r || !*r))
  		return 0;
  
  	return *r == data;
  }
  
  /**
   * devm_mdiobus_alloc_size - Resource-managed mdiobus_alloc_size()
   * @dev:		Device to allocate mii_bus for
   * @sizeof_priv:	Space to allocate for private structure.
   *
   * Managed mdiobus_alloc_size. mii_bus allocated with this function is
   * automatically freed on driver detach.
   *
   * If an mii_bus allocated with this function needs to be freed separately,
   * devm_mdiobus_free() must be used.
   *
   * RETURNS:
   * Pointer to allocated mii_bus on success, NULL on failure.
   */
  struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv)
  {
  	struct mii_bus **ptr, *bus;
  
  	ptr = devres_alloc(_devm_mdiobus_free, sizeof(*ptr), GFP_KERNEL);
  	if (!ptr)
  		return NULL;
  
  	/* use raw alloc_dr for kmalloc caller tracing */
  	bus = mdiobus_alloc_size(sizeof_priv);
  	if (bus) {
  		*ptr = bus;
  		devres_add(dev, ptr);
  	} else {
  		devres_free(ptr);
  	}
  
  	return bus;
  }
  EXPORT_SYMBOL_GPL(devm_mdiobus_alloc_size);
  
  /**
   * devm_mdiobus_free - Resource-managed mdiobus_free()
   * @dev:		Device this mii_bus belongs to
   * @bus:		the mii_bus associated with the device
   *
   * Free mii_bus allocated with devm_mdiobus_alloc_size().
   */
  void devm_mdiobus_free(struct device *dev, struct mii_bus *bus)
  {
  	int rc;
  
  	rc = devres_release(dev, _devm_mdiobus_free,
  			    devm_mdiobus_match, bus);
  	WARN_ON(rc);
  }
  EXPORT_SYMBOL_GPL(devm_mdiobus_free);
  
  /**
   * 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 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(&mdio_bus_class, NULL,  mdio_bus_np,
  			      of_mdio_bus_match);
  
  	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
   * phy's address with its 'reg' property. If found, set the of_node pointer for
   * the phy. This allows auto-probed pyh devices to be supplied with information
   * passed in via DT.
   */
  static void of_mdiobus_link_phydev(struct mii_bus *mdio,
  				   struct phy_device *phydev)
  {
  	struct device *dev = &phydev->dev;
  	struct device_node *child;
  
  	if (dev->of_node || !mdio->dev.of_node)
  		return;
  
  	for_each_available_child_of_node(mdio->dev.of_node, child) {
  		int addr;
  		int ret;
  
  		ret = of_property_read_u32(child, "reg", &addr);
  		if (ret < 0) {
  			dev_err(dev, "%s has invalid PHY address
  ",
  				child->full_name);
  			continue;
  		}
  
  		/* A PHY must have a reg property in the range [0-31] */
  		if (addr >= PHY_MAX_ADDR) {
  			dev_err(dev, "%s PHY address %i is too large
  ",
  				child->full_name, addr);
  			continue;
  		}
  
  		if (addr == phydev->addr) {
  			dev->of_node = child;
  			return;
  		}
  	}
  }
  #else /* !IS_ENABLED(CONFIG_OF_MDIO) */
  static inline void of_mdiobus_link_phydev(struct mii_bus *mdio,
  					  struct phy_device *phydev)
  {
  }
  #endif
  
  /**
   * __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.
   *
   * Returns 0 on success or < 0 on error.
   */
  int __mdiobus_register(struct mii_bus *bus, struct module *owner)
  {
  	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->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);
  
  	err = device_register(&bus->dev);
  	if (err) {
  		pr_err("mii_bus %s failed to register
  ", bus->id);
  		put_device(&bus->dev);
  		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
  ", bus->name);
  	return 0;
  
  error:
  	while (--i >= 0) {
  		struct phy_device *phydev = bus->phy_map[i];
  		if (phydev) {
  			phy_device_remove(phydev);
  			phy_device_free(phydev);
  		}
  	}
  	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;
  
  	for (i = 0; i < PHY_MAX_ADDR; i++) {
  		struct phy_device *phydev = bus->phy_map[i];
  		if (phydev) {
  			phy_device_remove(phydev);
  			phy_device_free(phydev);
  		}
  	}
  	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;
  	}
  
  	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;
  
  	/*
  	 * For DT, see if the auto-probed phy has a correspoding child
  	 * in the bus node, and set the of_node pointer in this case.
  	 */
  	of_mdiobus_link_phydev(bus, phydev);
  
  	err = phy_device_register(phydev);
  	if (err) {
  		phy_device_free(phydev);
  		return NULL;
  	}
  
  	return phydev;
  }
  EXPORT_SYMBOL(mdiobus_scan);
  
  /**
   * 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;
  
  	BUG_ON(in_interrupt());
  
  	mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING);
  	retval = bus->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;
  
  	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_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;
  
  	BUG_ON(in_interrupt());
  
  	mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING);
  	err = bus->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;
  
  	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);
  	const int num_ids = ARRAY_SIZE(phydev->c45_ids.device_ids);
  	int i;
  
  	if (of_driver_match_device(dev, drv))
  		return 1;
  
  	if (phydrv->match_phy_device)
  		return phydrv->match_phy_device(phydev);
  
  	if (phydev->is_c45) {
  		for (i = 1; i < num_ids; i++) {
  			if (!(phydev->c45_ids.devices_in_package & (1 << i)))
  				continue;
  
  			if ((phydrv->phy_id & phydrv->phy_id_mask) ==
  			    (phydev->c45_ids.device_ids[i] &
  			     phydrv->phy_id_mask))
  				return 1;
  		}
  		return 0;
  	} else {
  		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 the PHY has not already been
  	 * suspended as part of a prior call to phy_disconnect() ->
  	 * phy_detach() -> phy_suspend() because the parent netdev might be the
  	 * MDIO bus driver and clock gated at this point.
  	 */
  	if (!netdev)
  		return !phydev->suspended;
  
  	/* 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_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 phy_suspend(phydev);
  }
  
  static int mdio_bus_resume(struct device *dev)
  {
  	struct phy_device *phydev = to_phy_device(dev);
  	int ret;
  
  	if (!mdio_bus_phy_may_suspend(phydev))
  		goto no_resume;
  
  	ret = phy_resume(phydev);
  	if (ret < 0)
  		return ret;
  
  no_resume:
  	if (phydev->attached_dev && phydev->adjust_link)
  		phy_start_machine(phydev);
  
  	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);
  
  	return 0;
  }
  
  static const 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
  ", (unsigned long)phydev->phy_id);
  }
  static DEVICE_ATTR_RO(phy_id);
  
  static ssize_t
  phy_interface_show(struct device *dev, struct device_attribute *attr, char *buf)
  {
  	struct phy_device *phydev = to_phy_device(dev);
  	const char *mode = NULL;
  
  	if (phy_is_internal(phydev))
  		mode = "internal";
  	else
  		mode = phy_modes(phydev->interface);
  
  	return sprintf(buf, "%s
  ", mode);
  }
  static DEVICE_ATTR_RO(phy_interface);
  
  static ssize_t
  phy_has_fixups_show(struct device *dev, struct device_attribute *attr, char *buf)
  {
  	struct phy_device *phydev = to_phy_device(dev);
  
  	return sprintf(buf, "%d
  ", phydev->has_fixups);
  }
  static DEVICE_ATTR_RO(phy_has_fixups);
  
  static struct attribute *mdio_dev_attrs[] = {
  	&dev_attr_phy_id.attr,
  	&dev_attr_phy_interface.attr,
  	&dev_attr_phy_has_fixups.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);
  }