#include <linux/export.h>
  #include <linux/kref.h>
  #include <linux/list.h>
  #include <linux/mutex.h>
  #include <linux/phylink.h>
  #include <linux/rtnetlink.h>
  #include <linux/slab.h>
  
  #include "sfp.h"

  /**
   * struct sfp_bus - internal representation of a sfp bus
   */

  struct sfp_bus {

  	/* private: */

  	struct kref kref;
  	struct list_head node;

  	struct fwnode_handle *fwnode;

  
  	const struct sfp_socket_ops *socket_ops;
  	struct device *sfp_dev;
  	struct sfp *sfp;
  
  	const struct sfp_upstream_ops *upstream_ops;
  	void *upstream;
  	struct net_device *netdev;
  	struct phy_device *phydev;
  
  	bool registered;
  	bool started;
  };

  /**
   * sfp_parse_port() - Parse the EEPROM base ID, setting the port type
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   * @id: a pointer to the module's &struct sfp_eeprom_id
   * @support: optional pointer to an array of unsigned long for the
   *   ethtool support mask
   *
   * Parse the EEPROM identification given in @id, and return one of
   * %PORT_TP, %PORT_FIBRE or %PORT_OTHER. If @support is non-%NULL,
   * also set the ethtool %ETHTOOL_LINK_MODE_xxx_BIT corresponding with
   * the connector type.
   *
   * If the port type is not known, returns %PORT_OTHER.
   */

  int sfp_parse_port(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
  		   unsigned long *support)
  {
  	int port;
  
  	/* port is the physical connector, set this from the connector field. */
  	switch (id->base.connector) {
  	case SFP_CONNECTOR_SC:
  	case SFP_CONNECTOR_FIBERJACK:
  	case SFP_CONNECTOR_LC:
  	case SFP_CONNECTOR_MT_RJ:
  	case SFP_CONNECTOR_MU:
  	case SFP_CONNECTOR_OPTICAL_PIGTAIL:

  		port = PORT_FIBRE;
  		break;
  
  	case SFP_CONNECTOR_RJ45:

  		port = PORT_TP;
  		break;

  	case SFP_CONNECTOR_COPPER_PIGTAIL:
  		port = PORT_DA;
  		break;

  	case SFP_CONNECTOR_UNSPEC:
  		if (id->base.e1000_base_t) {

  			port = PORT_TP;
  			break;
  		}
  		/* fallthrough */
  	case SFP_CONNECTOR_SG: /* guess */
  	case SFP_CONNECTOR_MPO_1X12:
  	case SFP_CONNECTOR_MPO_2X16:
  	case SFP_CONNECTOR_HSSDC_II:

  	case SFP_CONNECTOR_NOSEPARATE:
  	case SFP_CONNECTOR_MXC_2X16:
  		port = PORT_OTHER;
  		break;
  	default:
  		dev_warn(bus->sfp_dev, "SFP: unknown connector id 0x%02x
  ",
  			 id->base.connector);
  		port = PORT_OTHER;
  		break;
  	}

  	if (support) {
  		switch (port) {
  		case PORT_FIBRE:
  			phylink_set(support, FIBRE);
  			break;
  
  		case PORT_TP:
  			phylink_set(support, TP);
  			break;
  		}
  	}

  	return port;
  }
  EXPORT_SYMBOL_GPL(sfp_parse_port);

  /**

   * sfp_parse_support() - Parse the eeprom id for supported link modes
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   * @id: a pointer to the module's &struct sfp_eeprom_id
   * @support: pointer to an array of unsigned long for the ethtool support mask
   *
   * Parse the EEPROM identification information and derive the supported
   * ethtool link modes for the module.
   */

  void sfp_parse_support(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
  		       unsigned long *support)
  {

  	unsigned int br_min, br_nom, br_max;

  	__ETHTOOL_DECLARE_LINK_MODE_MASK(modes) = { 0, };

  	/* Decode the bitrate information to MBd */
  	br_min = br_nom = br_max = 0;
  	if (id->base.br_nominal) {
  		if (id->base.br_nominal != 255) {
  			br_nom = id->base.br_nominal * 100;

  			br_min = br_nom - id->base.br_nominal * id->ext.br_min;

  			br_max = br_nom + id->base.br_nominal * id->ext.br_max;
  		} else if (id->ext.br_max) {
  			br_nom = 250 * id->ext.br_max;
  			br_max = br_nom + br_nom * id->ext.br_min / 100;
  			br_min = br_nom - br_nom * id->ext.br_min / 100;
  		}

  
  		/* When using passive cables, in case neither BR,min nor BR,max
  		 * are specified, set br_min to 0 as the nominal value is then
  		 * used as the maximum.
  		 */
  		if (br_min == br_max && id->base.sfp_ct_passive)
  			br_min = 0;

  	}

  	/* Set ethtool support from the compliance fields. */
  	if (id->base.e10g_base_sr)

  		phylink_set(modes, 10000baseSR_Full);

  	if (id->base.e10g_base_lr)

  		phylink_set(modes, 10000baseLR_Full);

  	if (id->base.e10g_base_lrm)

  		phylink_set(modes, 10000baseLRM_Full);

  	if (id->base.e10g_base_er)

  		phylink_set(modes, 10000baseER_Full);

  	if (id->base.e1000_base_sx ||
  	    id->base.e1000_base_lx ||
  	    id->base.e1000_base_cx)

  		phylink_set(modes, 1000baseX_Full);

  	if (id->base.e1000_base_t) {

  		phylink_set(modes, 1000baseT_Half);
  		phylink_set(modes, 1000baseT_Full);

  	}

  	/* 1000Base-PX or 1000Base-BX10 */
  	if ((id->base.e_base_px || id->base.e_base_bx10) &&
  	    br_min <= 1300 && br_max >= 1200)

  		phylink_set(modes, 1000baseX_Full);

  	/* For active or passive cables, select the link modes
  	 * based on the bit rates and the cable compliance bytes.
  	 */
  	if ((id->base.sfp_ct_passive || id->base.sfp_ct_active) && br_nom) {
  		/* This may look odd, but some manufacturers use 12000MBd */
  		if (br_min <= 12000 && br_max >= 10300)

  			phylink_set(modes, 10000baseCR_Full);

  		if (br_min <= 3200 && br_max >= 3100)

  			phylink_set(modes, 2500baseX_Full);

  		if (br_min <= 1300 && br_max >= 1200)

  			phylink_set(modes, 1000baseX_Full);

  	}
  	if (id->base.sfp_ct_passive) {
  		if (id->base.passive.sff8431_app_e)

  			phylink_set(modes, 10000baseCR_Full);

  	}
  	if (id->base.sfp_ct_active) {
  		if (id->base.active.sff8431_app_e ||
  		    id->base.active.sff8431_lim) {

  			phylink_set(modes, 10000baseCR_Full);

  		}
  	}

  	switch (id->base.extended_cc) {
  	case 0x00: /* Unspecified */
  		break;
  	case 0x02: /* 100Gbase-SR4 or 25Gbase-SR */

  		phylink_set(modes, 100000baseSR4_Full);
  		phylink_set(modes, 25000baseSR_Full);

  		break;
  	case 0x03: /* 100Gbase-LR4 or 25Gbase-LR */
  	case 0x04: /* 100Gbase-ER4 or 25Gbase-ER */

  		phylink_set(modes, 100000baseLR4_ER4_Full);

  		break;
  	case 0x0b: /* 100Gbase-CR4 or 25Gbase-CR CA-L */
  	case 0x0c: /* 25Gbase-CR CA-S */
  	case 0x0d: /* 25Gbase-CR CA-N */

  		phylink_set(modes, 100000baseCR4_Full);
  		phylink_set(modes, 25000baseCR_Full);

  		break;
  	default:
  		dev_warn(bus->sfp_dev,
  			 "Unknown/unsupported extended compliance code: 0x%02x
  ",
  			 id->base.extended_cc);
  		break;
  	}
  
  	/* For fibre channel SFP, derive possible BaseX modes */
  	if (id->base.fc_speed_100 ||
  	    id->base.fc_speed_200 ||
  	    id->base.fc_speed_400) {
  		if (id->base.br_nominal >= 31)

  			phylink_set(modes, 2500baseX_Full);

  		if (id->base.br_nominal >= 12)

  			phylink_set(modes, 1000baseX_Full);

  	}

  
  	/* If we haven't discovered any modes that this module supports, try
  	 * the encoding and bitrate to determine supported modes. Some BiDi
  	 * modules (eg, 1310nm/1550nm) are not 1000BASE-BX compliant due to
  	 * the differing wavelengths, so do not set any transceiver bits.
  	 */
  	if (bitmap_empty(modes, __ETHTOOL_LINK_MODE_MASK_NBITS)) {
  		/* If the encoding and bit rate allows 1000baseX */
  		if (id->base.encoding == SFP_ENCODING_8B10B && br_nom &&
  		    br_min <= 1300 && br_max >= 1200)
  			phylink_set(modes, 1000baseX_Full);
  	}
  
  	bitmap_or(support, support, modes, __ETHTOOL_LINK_MODE_MASK_NBITS);
  
  	phylink_set(support, Autoneg);
  	phylink_set(support, Pause);
  	phylink_set(support, Asym_Pause);

  }
  EXPORT_SYMBOL_GPL(sfp_parse_support);

  /**
   * sfp_select_interface() - Select appropriate phy_interface_t mode
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   * @id: a pointer to the module's &struct sfp_eeprom_id
   * @link_modes: ethtool link modes mask
   *
   * Derive the phy_interface_t mode for the information found in the
   * module's identifying EEPROM and the link modes mask. There is no
   * standard or defined way to derive this information, so we decide
   * based upon the link mode mask.
   */
  phy_interface_t sfp_select_interface(struct sfp_bus *bus,
  				     const struct sfp_eeprom_id *id,
  				     unsigned long *link_modes)
  {
  	if (phylink_test(link_modes, 10000baseCR_Full) ||
  	    phylink_test(link_modes, 10000baseSR_Full) ||
  	    phylink_test(link_modes, 10000baseLR_Full) ||
  	    phylink_test(link_modes, 10000baseLRM_Full) ||
  	    phylink_test(link_modes, 10000baseER_Full))
  		return PHY_INTERFACE_MODE_10GKR;
  
  	if (phylink_test(link_modes, 2500baseX_Full))
  		return PHY_INTERFACE_MODE_2500BASEX;
  
  	if (id->base.e1000_base_t ||
  	    id->base.e100_base_lx ||
  	    id->base.e100_base_fx)
  		return PHY_INTERFACE_MODE_SGMII;
  
  	if (phylink_test(link_modes, 1000baseX_Full))
  		return PHY_INTERFACE_MODE_1000BASEX;
  
  	dev_warn(bus->sfp_dev, "Unable to ascertain link mode
  ");
  
  	return PHY_INTERFACE_MODE_NA;
  }
  EXPORT_SYMBOL_GPL(sfp_select_interface);

  static LIST_HEAD(sfp_buses);
  static DEFINE_MUTEX(sfp_mutex);
  
  static const struct sfp_upstream_ops *sfp_get_upstream_ops(struct sfp_bus *bus)
  {
  	return bus->registered ? bus->upstream_ops : NULL;
  }

  static struct sfp_bus *sfp_bus_get(struct fwnode_handle *fwnode)

  {
  	struct sfp_bus *sfp, *new, *found = NULL;
  
  	new = kzalloc(sizeof(*new), GFP_KERNEL);
  
  	mutex_lock(&sfp_mutex);
  
  	list_for_each_entry(sfp, &sfp_buses, node) {

  		if (sfp->fwnode == fwnode) {

  			kref_get(&sfp->kref);
  			found = sfp;
  			break;
  		}
  	}
  
  	if (!found && new) {
  		kref_init(&new->kref);

  		new->fwnode = fwnode;

  		list_add(&new->node, &sfp_buses);
  		found = new;
  		new = NULL;
  	}
  
  	mutex_unlock(&sfp_mutex);
  
  	kfree(new);
  
  	return found;
  }

  static void sfp_bus_release(struct kref *kref)

  {
  	struct sfp_bus *bus = container_of(kref, struct sfp_bus, kref);
  
  	list_del(&bus->node);
  	mutex_unlock(&sfp_mutex);
  	kfree(bus);
  }
  
  static void sfp_bus_put(struct sfp_bus *bus)
  {
  	kref_put_mutex(&bus->kref, sfp_bus_release, &sfp_mutex);
  }
  
  static int sfp_register_bus(struct sfp_bus *bus)
  {
  	const struct sfp_upstream_ops *ops = bus->upstream_ops;
  	int ret;
  
  	if (ops) {
  		if (ops->link_down)
  			ops->link_down(bus->upstream);
  		if (ops->connect_phy && bus->phydev) {
  			ret = ops->connect_phy(bus->upstream, bus->phydev);
  			if (ret)
  				return ret;
  		}
  	}

  	bus->socket_ops->attach(bus->sfp);

  	if (bus->started)
  		bus->socket_ops->start(bus->sfp);

  	bus->netdev->sfp_bus = bus;

  	bus->registered = true;
  	return 0;
  }
  
  static void sfp_unregister_bus(struct sfp_bus *bus)
  {
  	const struct sfp_upstream_ops *ops = bus->upstream_ops;

  	bus->netdev->sfp_bus = NULL;

  	if (bus->registered) {
  		if (bus->started)
  			bus->socket_ops->stop(bus->sfp);

  		bus->socket_ops->detach(bus->sfp);

  		if (bus->phydev && ops && ops->disconnect_phy)
  			ops->disconnect_phy(bus->upstream);
  	}
  	bus->registered = false;
  }

  /**
   * sfp_get_module_info() - Get the ethtool_modinfo for a SFP module
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   * @modinfo: a &struct ethtool_modinfo
   *
   * Fill in the type and eeprom_len parameters in @modinfo for a module on
   * the sfp bus specified by @bus.
   *
   * Returns 0 on success or a negative errno number.
   */

  int sfp_get_module_info(struct sfp_bus *bus, struct ethtool_modinfo *modinfo)
  {

  	return bus->socket_ops->module_info(bus->sfp, modinfo);
  }
  EXPORT_SYMBOL_GPL(sfp_get_module_info);

  /**
   * sfp_get_module_eeprom() - Read the SFP module EEPROM
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   * @ee: a &struct ethtool_eeprom
   * @data: buffer to contain the EEPROM data (must be at least @ee->len bytes)
   *
   * Read the EEPROM as specified by the supplied @ee. See the documentation
   * for &struct ethtool_eeprom for the region to be read.
   *
   * Returns 0 on success or a negative errno number.
   */

  int sfp_get_module_eeprom(struct sfp_bus *bus, struct ethtool_eeprom *ee,

  			  u8 *data)

  {

  	return bus->socket_ops->module_eeprom(bus->sfp, ee, data);
  }
  EXPORT_SYMBOL_GPL(sfp_get_module_eeprom);

  /**
   * sfp_upstream_start() - Inform the SFP that the network device is up
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   *
   * Inform the SFP socket that the network device is now up, so that the
   * module can be enabled by allowing TX_DISABLE to be deasserted. This
   * should be called from the network device driver's &struct net_device_ops
   * ndo_open() method.
   */

  void sfp_upstream_start(struct sfp_bus *bus)
  {
  	if (bus->registered)
  		bus->socket_ops->start(bus->sfp);
  	bus->started = true;
  }
  EXPORT_SYMBOL_GPL(sfp_upstream_start);

  /**
   * sfp_upstream_stop() - Inform the SFP that the network device is down
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   *
   * Inform the SFP socket that the network device is now up, so that the
   * module can be disabled by asserting TX_DISABLE, disabling the laser
   * in optical modules. This should be called from the network device
   * driver's &struct net_device_ops ndo_stop() method.
   */

  void sfp_upstream_stop(struct sfp_bus *bus)
  {
  	if (bus->registered)
  		bus->socket_ops->stop(bus->sfp);
  	bus->started = false;
  }
  EXPORT_SYMBOL_GPL(sfp_upstream_stop);

  static void sfp_upstream_clear(struct sfp_bus *bus)
  {
  	bus->upstream_ops = NULL;
  	bus->upstream = NULL;
  	bus->netdev = NULL;
  }

  /**
   * sfp_register_upstream() - Register the neighbouring device

   * @fwnode: firmware node for the SFP bus

   * @ndev: network device associated with the interface
   * @upstream: the upstream private data
   * @ops: the upstream's &struct sfp_upstream_ops
   *
   * Register the upstream device (eg, PHY) with the SFP bus. MAC drivers
   * should use phylink, which will call this function for them. Returns
   * a pointer to the allocated &struct sfp_bus.
   *
   * On error, returns %NULL.
   */

  struct sfp_bus *sfp_register_upstream(struct fwnode_handle *fwnode,

  				      struct net_device *ndev, void *upstream,
  				      const struct sfp_upstream_ops *ops)

  {

  	struct sfp_bus *bus = sfp_bus_get(fwnode);

  	int ret = 0;
  
  	if (bus) {
  		rtnl_lock();
  		bus->upstream_ops = ops;
  		bus->upstream = upstream;
  		bus->netdev = ndev;

  		if (bus->sfp) {

  			ret = sfp_register_bus(bus);

  			if (ret)
  				sfp_upstream_clear(bus);
  		}

  		rtnl_unlock();
  	}
  
  	if (ret) {
  		sfp_bus_put(bus);
  		bus = NULL;
  	}
  
  	return bus;
  }
  EXPORT_SYMBOL_GPL(sfp_register_upstream);

  /**
   * sfp_unregister_upstream() - Unregister sfp bus
   * @bus: a pointer to the &struct sfp_bus structure for the sfp module
   *
   * Unregister a previously registered upstream connection for the SFP
   * module. @bus is returned from sfp_register_upstream().
   */

  void sfp_unregister_upstream(struct sfp_bus *bus)
  {
  	rtnl_lock();

  	if (bus->sfp)
  		sfp_unregister_bus(bus);

  	sfp_upstream_clear(bus);

  	rtnl_unlock();
  
  	sfp_bus_put(bus);
  }
  EXPORT_SYMBOL_GPL(sfp_unregister_upstream);

  /* Socket driver entry points */
  int sfp_add_phy(struct sfp_bus *bus, struct phy_device *phydev)
  {
  	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
  	int ret = 0;
  
  	if (ops && ops->connect_phy)
  		ret = ops->connect_phy(bus->upstream, phydev);
  
  	if (ret == 0)
  		bus->phydev = phydev;
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(sfp_add_phy);
  
  void sfp_remove_phy(struct sfp_bus *bus)
  {
  	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
  
  	if (ops && ops->disconnect_phy)
  		ops->disconnect_phy(bus->upstream);
  	bus->phydev = NULL;
  }
  EXPORT_SYMBOL_GPL(sfp_remove_phy);

  void sfp_link_up(struct sfp_bus *bus)
  {
  	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
  
  	if (ops && ops->link_up)
  		ops->link_up(bus->upstream);
  }
  EXPORT_SYMBOL_GPL(sfp_link_up);
  
  void sfp_link_down(struct sfp_bus *bus)
  {
  	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
  
  	if (ops && ops->link_down)
  		ops->link_down(bus->upstream);
  }
  EXPORT_SYMBOL_GPL(sfp_link_down);
  
  int sfp_module_insert(struct sfp_bus *bus, const struct sfp_eeprom_id *id)
  {
  	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
  	int ret = 0;
  
  	if (ops && ops->module_insert)
  		ret = ops->module_insert(bus->upstream, id);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(sfp_module_insert);
  
  void sfp_module_remove(struct sfp_bus *bus)
  {
  	const struct sfp_upstream_ops *ops = sfp_get_upstream_ops(bus);
  
  	if (ops && ops->module_remove)
  		ops->module_remove(bus->upstream);
  }
  EXPORT_SYMBOL_GPL(sfp_module_remove);

  static void sfp_socket_clear(struct sfp_bus *bus)
  {
  	bus->sfp_dev = NULL;
  	bus->sfp = NULL;
  	bus->socket_ops = NULL;
  }

  struct sfp_bus *sfp_register_socket(struct device *dev, struct sfp *sfp,
  				    const struct sfp_socket_ops *ops)
  {

  	struct sfp_bus *bus = sfp_bus_get(dev->fwnode);

  	int ret = 0;
  
  	if (bus) {
  		rtnl_lock();
  		bus->sfp_dev = dev;
  		bus->sfp = sfp;
  		bus->socket_ops = ops;

  		if (bus->netdev) {

  			ret = sfp_register_bus(bus);

  			if (ret)
  				sfp_socket_clear(bus);
  		}

  		rtnl_unlock();
  	}
  
  	if (ret) {
  		sfp_bus_put(bus);
  		bus = NULL;
  	}
  
  	return bus;
  }
  EXPORT_SYMBOL_GPL(sfp_register_socket);
  
  void sfp_unregister_socket(struct sfp_bus *bus)
  {
  	rtnl_lock();

  	if (bus->netdev)
  		sfp_unregister_bus(bus);

  	sfp_socket_clear(bus);

  	rtnl_unlock();
  
  	sfp_bus_put(bus);
  }
  EXPORT_SYMBOL_GPL(sfp_unregister_socket);