phylink: add documentation for kernel APIs

Add kernel-doc documentation for phylink kernel APIs, and link it into
the networking kapi documentation under "Network device support".
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/kapi.rst

@@ -145,3 +145,15 @@ PHY Support
 
 .. kernel-doc:: drivers/net/phy/mdio_bus.c
    :internal:
+
+PHYLINK
+-------
+
+  PHYLINK interfaces traditional network drivers with PHYLIB, fixed-links,
+  and SFF modules (eg, hot-pluggable SFP) that may contain PHYs.  PHYLINK
+  provides management of the link state and link modes.
+
+.. kernel-doc:: include/linux/phylink.h
+   :internal:
+
+.. kernel-doc:: drivers/net/phy/phylink.c

drivers/net/phy/phylink.c

@@ -36,7 +36,11 @@ enum {
 	PHYLINK_DISABLE_LINK,
 };
 
+/**
+ * struct phylink - internal data type for phylink
+ */
 struct phylink {
+	/* private: */
 	struct net_device *netdev;
 	const struct phylink_mac_ops *ops;
 
@@ -87,6 +91,13 @@ static inline bool linkmode_empty(const unsigned long *src)
 	return bitmap_empty(src, __ETHTOOL_LINK_MODE_MASK_NBITS);
 }
 
+/**
+ * phylink_set_port_modes() - set the port type modes in the ethtool mask
+ * @mask: ethtool link mode mask
+ *
+ * Sets all the port type modes in the ethtool mask.  MAC drivers should
+ * use this in their 'validate' callback.
+ */
 void phylink_set_port_modes(unsigned long *mask)
 {
 	phylink_set(mask, TP);
@@ -496,6 +507,19 @@ static int phylink_register_sfp(struct phylink *pl, struct device_node *np)
 	return 0;
 }
 
+/**
+ * phylink_create() - create a phylink instance
+ * @ndev: a pointer to the &struct net_device
+ * @np: a pointer to a &struct device_node describing the network interface
+ * @iface: the desired link mode defined by &typedef phy_interface_t
+ * @ops: a pointer to a &struct phylink_mac_ops for the MAC.
+ *
+ * Create a new phylink instance, and parse the link parameters found in @np.
+ * This will parse in-band modes, fixed-link or SFP configuration.
+ *
+ * Returns a pointer to a &struct phylink, or an error-pointer value. Users
+ * must use IS_ERR() to check for errors from this function.
+ */
 struct phylink *phylink_create(struct net_device *ndev, struct device_node *np,
 			       phy_interface_t iface,
 			       const struct phylink_mac_ops *ops)
@@ -548,6 +572,13 @@ struct phylink *phylink_create(struct net_device *ndev, struct device_node *np,
 }
 EXPORT_SYMBOL_GPL(phylink_create);
 
+/**
+ * phylink_destroy() - cleanup and destroy the phylink instance
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Destroy a phylink instance. Any PHY that has been attached must have been
+ * cleaned up via phylink_disconnect_phy() prior to calling this function.
+ */
 void phylink_destroy(struct phylink *pl)
 {
 	if (pl->sfp_bus)
@@ -644,6 +675,21 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy)
 	return 0;
 }
 
+/**
+ * phylink_connect_phy() - connect a PHY to the phylink instance
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @phy: a pointer to a &struct phy_device.
+ *
+ * Connect @phy to the phylink instance specified by @pl by calling
+ * phy_attach_direct(). Configure the @phy according to the MAC driver's
+ * capabilities, start the PHYLIB state machine and enable any interrupts
+ * that the PHY supports.
+ *
+ * This updates the phylink's ethtool supported and advertising link mode
+ * masks.
+ *
+ * Returns 0 on success or a negative errno.
+ */
 int phylink_connect_phy(struct phylink *pl, struct phy_device *phy)
 {
 	int ret;
@@ -665,6 +711,17 @@ int phylink_connect_phy(struct phylink *pl, struct phy_device *phy)
 }
 EXPORT_SYMBOL_GPL(phylink_connect_phy);
 
+/**
+ * phylink_of_phy_connect() - connect the PHY specified in the DT mode.
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @dn: a pointer to a &struct device_node.
+ *
+ * Connect the phy specified in the device node @dn to the phylink instance
+ * specified by @pl. Actions specified in phylink_connect_phy() will be
+ * performed.
+ *
+ * Returns 0 on success or a negative errno.
+ */
 int phylink_of_phy_connect(struct phylink *pl, struct device_node *dn)
 {
 	struct device_node *phy_node;
@@ -706,6 +763,13 @@ int phylink_of_phy_connect(struct phylink *pl, struct device_node *dn)
 }
 EXPORT_SYMBOL_GPL(phylink_of_phy_connect);
 
+/**
+ * phylink_disconnect_phy() - disconnect any PHY attached to the phylink
+ *   instance.
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Disconnect any current PHY from the phylink instance described by @pl.
+ */
 void phylink_disconnect_phy(struct phylink *pl)
 {
 	struct phy_device *phy;
@@ -727,6 +791,14 @@ void phylink_disconnect_phy(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_disconnect_phy);
 
+/**
+ * phylink_mac_change() - notify phylink of a change in MAC state
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @up: indicates whether the link is currently up.
+ *
+ * The MAC driver should call this driver when the state of its link
+ * changes (eg, link failure, new negotiation results, etc.)
+ */
 void phylink_mac_change(struct phylink *pl, bool up)
 {
 	if (!up)
@@ -736,6 +808,14 @@ void phylink_mac_change(struct phylink *pl, bool up)
 }
 EXPORT_SYMBOL_GPL(phylink_mac_change);
 
+/**
+ * phylink_start() - start a phylink instance
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Start the phylink instance specified by @pl, configuring the MAC for the
+ * desired link mode(s) and negotiation style. This should be called from the
+ * network device driver's &struct net_device_ops ndo_open() method.
+ */
 void phylink_start(struct phylink *pl)
 {
 	WARN_ON(!lockdep_rtnl_is_held());
@@ -767,6 +847,15 @@ void phylink_start(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_start);
 
+/**
+ * phylink_stop() - stop a phylink instance
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Stop the phylink instance specified by @pl. This should be called from the
+ * network device driver's &struct net_device_ops ndo_stop() method.  The
+ * network device's carrier state should not be changed prior to calling this
+ * function.
+ */
 void phylink_stop(struct phylink *pl)
 {
 	WARN_ON(!lockdep_rtnl_is_held());
@@ -782,6 +871,15 @@ void phylink_stop(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_stop);
 
+/**
+ * phylink_ethtool_get_wol() - get the wake on lan parameters for the PHY
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @wol: a pointer to &struct ethtool_wolinfo to hold the read parameters
+ *
+ * Read the wake on lan parameters from the PHY attached to the phylink
+ * instance specified by @pl. If no PHY is currently attached, report no
+ * support for wake on lan.
+ */
 void phylink_ethtool_get_wol(struct phylink *pl, struct ethtool_wolinfo *wol)
 {
 	WARN_ON(!lockdep_rtnl_is_held());
@@ -794,6 +892,17 @@ void phylink_ethtool_get_wol(struct phylink *pl, struct ethtool_wolinfo *wol)
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_get_wol);
 
+/**
+ * phylink_ethtool_set_wol() - set wake on lan parameters
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @wol: a pointer to &struct ethtool_wolinfo for the desired parameters
+ *
+ * Set the wake on lan parameters for the PHY attached to the phylink
+ * instance specified by @pl. If no PHY is attached, returns %EOPNOTSUPP
+ * error.
+ *
+ * Returns zero on success or negative errno code.
+ */
 int phylink_ethtool_set_wol(struct phylink *pl, struct ethtool_wolinfo *wol)
 {
 	int ret = -EOPNOTSUPP;
@@ -829,6 +938,15 @@ static void phylink_get_ksettings(const struct phylink_link_state *state,
 				AUTONEG_DISABLE;
 }
 
+/**
+ * phylink_ethtool_ksettings_get() - get the current link settings
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @kset: a pointer to a &struct ethtool_link_ksettings to hold link settings
+ *
+ * Read the current link settings for the phylink instance specified by @pl.
+ * This will be the link settings read from the MAC, PHY or fixed link
+ * settings depending on the current negotiation mode.
+ */
 int phylink_ethtool_ksettings_get(struct phylink *pl,
 				  struct ethtool_link_ksettings *kset)
 {
@@ -875,6 +993,11 @@ int phylink_ethtool_ksettings_get(struct phylink *pl,
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_ksettings_get);
 
+/**
+ * phylink_ethtool_ksettings_set() - set the link settings
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @kset: a pointer to a &struct ethtool_link_ksettings for the desired modes
+ */
 int phylink_ethtool_ksettings_set(struct phylink *pl,
 				  const struct ethtool_link_ksettings *kset)
 {
@@ -968,6 +1091,17 @@ int phylink_ethtool_ksettings_set(struct phylink *pl,
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_ksettings_set);
 
+/**
+ * phylink_ethtool_nway_reset() - restart negotiation
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Restart negotiation for the phylink instance specified by @pl. This will
+ * cause any attached phy to restart negotiation with the link partner, and
+ * if the MAC is in a BaseX mode, the MAC will also be requested to restart
+ * negotiation.
+ *
+ * Returns zero on success, or negative error code.
+ */
 int phylink_ethtool_nway_reset(struct phylink *pl)
 {
 	int ret = 0;
@@ -982,6 +1116,11 @@ int phylink_ethtool_nway_reset(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_nway_reset);
 
+/**
+ * phylink_ethtool_get_pauseparam() - get the current pause parameters
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @pause: a pointer to a &struct ethtool_pauseparam
+ */
 void phylink_ethtool_get_pauseparam(struct phylink *pl,
 				    struct ethtool_pauseparam *pause)
 {
@@ -993,6 +1132,11 @@ void phylink_ethtool_get_pauseparam(struct phylink *pl,
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_get_pauseparam);
 
+/**
+ * phylink_ethtool_set_pauseparam() - set the current pause parameters
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @pause: a pointer to a &struct ethtool_pauseparam
+ */
 int phylink_ethtool_set_pauseparam(struct phylink *pl,
 				   struct ethtool_pauseparam *pause)
 {
@@ -1070,6 +1214,16 @@ int phylink_ethtool_get_module_eeprom(struct phylink *pl,
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_get_module_eeprom);
 
+/**
+ * phylink_ethtool_get_eee_err() - read the energy efficient ethernet error
+ *   counter
+ * @pl: a pointer to a &struct phylink returned from phylink_create().
+ *
+ * Read the Energy Efficient Ethernet error counter from the PHY associated
+ * with the phylink instance specified by @pl.
+ *
+ * Returns positive error counter value, or negative error code.
+ */
 int phylink_get_eee_err(struct phylink *pl)
 {
 	int ret = 0;
@@ -1083,6 +1237,11 @@ int phylink_get_eee_err(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_get_eee_err);
 
+/**
+ * phylink_ethtool_get_eee() - read the energy efficient ethernet parameters
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @eee: a pointer to a &struct ethtool_eee for the read parameters
+ */
 int phylink_ethtool_get_eee(struct phylink *pl, struct ethtool_eee *eee)
 {
 	int ret = -EOPNOTSUPP;
@@ -1096,6 +1255,11 @@ int phylink_ethtool_get_eee(struct phylink *pl, struct ethtool_eee *eee)
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_get_eee);
 
+/**
+ * phylink_ethtool_set_eee() - set the energy efficient ethernet parameters
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @eee: a pointer to a &struct ethtool_eee for the desired parameters
+ */
 int phylink_ethtool_set_eee(struct phylink *pl, struct ethtool_eee *eee)
 {
 	int ret = -EOPNOTSUPP;
@@ -1267,6 +1431,24 @@ static int phylink_mii_write(struct phylink *pl, unsigned int phy_id,
 	return 0;
 }
 
+/**
+ * phylink_mii_ioctl() - generic mii ioctl interface
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @ifr: a pointer to a &struct ifreq for socket ioctls
+ * @cmd: ioctl cmd to execute
+ *
+ * Perform the specified MII ioctl on the PHY attached to the phylink instance
+ * specified by @pl. If no PHY is attached, emulate the presence of the PHY.
+ *
+ * Returns: zero on success or negative error code.
+ *
+ * %SIOCGMIIPHY:
+ *  read register from the current PHY.
+ * %SIOCGMIIREG:
+ *  read register from the specified PHY.
+ * %SIOCSMIIREG:
+ *  set a register on the specified PHY.
+ */
 int phylink_mii_ioctl(struct phylink *pl, struct ifreq *ifr, int cmd)
 {
 	struct mii_ioctl_data *mii = if_mii(ifr);

include/linux/phylink.h

@@ -28,10 +28,23 @@ static inline bool phylink_autoneg_inband(unsigned int mode)
 	return mode == MLO_AN_INBAND;
 }
 
+/**
+ * struct phylink_link_state - link state structure
+ * @advertising: ethtool bitmask containing advertised link modes
+ * @lp_advertising: ethtool bitmask containing link partner advertised link
+ *   modes
+ * @interface: link &typedef phy_interface_t mode
+ * @speed: link speed, one of the SPEED_* constants.
+ * @duplex: link duplex mode, one of DUPLEX_* constants.
+ * @pause: link pause state, described by MLO_PAUSE_* constants.
+ * @link: true if the link is up.
+ * @an_enabled: true if autonegotiation is enabled/desired.
+ * @an_complete: true if autonegotiation has completed.
+ */
 struct phylink_link_state {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(advertising);
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(lp_advertising);
-	phy_interface_t interface;	/* PHY_INTERFACE_xxx */
+	phy_interface_t interface;
 	int speed;
 	int duplex;
 	int pause;
@@ -40,60 +53,134 @@ struct phylink_link_state {
 	unsigned int an_complete:1;
 };
 
+/**
+ * struct phylink_mac_ops - MAC operations structure.
+ * @validate: Validate and update the link configuration.
+ * @mac_link_state: Read the current link state from the hardware.
+ * @mac_config: configure the MAC for the selected mode and state.
+ * @mac_an_restart: restart 802.3z BaseX autonegotiation.
+ * @mac_link_down: take the link down.
+ * @mac_link_up: allow the link to come up.
+ *
+ * The individual methods are described more fully below.
+ */
 struct phylink_mac_ops {
-	/**
-	 * validate: validate and update the link configuration
-	 * @ndev: net_device structure associated with MAC
-	 * @config: configuration to validate
+	void (*validate)(struct net_device *ndev, unsigned long *supported,
+			 struct phylink_link_state *state);
+	int (*mac_link_state)(struct net_device *ndev,
+			      struct phylink_link_state *state);
+	void (*mac_config)(struct net_device *ndev, unsigned int mode,
+			   const struct phylink_link_state *state);
+	void (*mac_an_restart)(struct net_device *ndev);
+	void (*mac_link_down)(struct net_device *ndev, unsigned int mode);
+	void (*mac_link_up)(struct net_device *ndev, unsigned int mode,
+			    struct phy_device *phy);
+};
+
+#if 0 /* For kernel-doc purposes only. */
+/**
+ * validate - Validate and update the link configuration
+ * @ndev: a pointer to a &struct net_device for the MAC.
+ * @supported: ethtool bitmask for supported link modes.
+ * @state: a pointer to a &struct phylink_link_state.
  *
-	 * Update the %config->supported and %config->advertised masks
-	 * clearing bits that can not be supported.
+ * Clear bits in the @supported and @state->advertising masks that
+ * are not supportable by the MAC.
  *
-	 * Note: the PHY may be able to transform from one connection
+ * Note that the PHY may be able to transform from one connection
  * technology to another, so, eg, don't clear 1000BaseX just
-	 * because the MAC is unable to support it.  This is more about
+ * because the MAC is unable to BaseX mode. This is more about
  * clearing unsupported speeds and duplex settings.
  *
-	 * If the %config->interface mode is %PHY_INTERFACE_MODE_1000BASEX
+ * If the @state->interface mode is %PHY_INTERFACE_MODE_1000BASEX
  * or %PHY_INTERFACE_MODE_2500BASEX, select the appropriate mode
-	 * based on %config->advertised and/or %config->speed.
+ * based on @state->advertising and/or @state->speed and update
+ * @state->interface accordingly.
  */
-	void (*validate)(struct net_device *ndev, unsigned long *supported,
+void validate(struct net_device *ndev, unsigned long *supported,
 	      struct phylink_link_state *state);
 
-	/* Read the current link state from the hardware */
-	int (*mac_link_state)(struct net_device *, struct phylink_link_state *);
+/**
+ * mac_link_state() - Read the current link state from the hardware
+ * @ndev: a pointer to a &struct net_device for the MAC.
+ * @state: a pointer to a &struct phylink_link_state.
+ *
+ * Read the current link state from the MAC, reporting the current
+ * speed in @state->speed, duplex mode in @state->duplex, pause mode
+ * in @state->pause using the %MLO_PAUSE_RX and %MLO_PAUSE_TX bits,
+ * negotiation completion state in @state->an_complete, and link
+ * up state in @state->link.
+ */
+int mac_link_state(struct net_device *ndev,
+		   struct phylink_link_state *state);
 
-	/* Configure the MAC */
-	/**
-	 * mac_config: configure the MAC for the selected mode and state
-	 * @ndev: net_device structure for the MAC
-	 * @mode: one of MLO_AN_FIXED, MLO_AN_PHY, MLO_AN_INBAND
-	 * @state: state structure
+/**
+ * mac_config() - configure the MAC for the selected mode and state
+ * @ndev: a pointer to a &struct net_device for the MAC.
+ * @mode: one of %MLO_AN_FIXED, %MLO_AN_PHY, %MLO_AN_INBAND.
+ * @state: a pointer to a &struct phylink_link_state.
  *
  * The action performed depends on the currently selected mode:
  *
  * %MLO_AN_FIXED, %MLO_AN_PHY:
-	 *   set the specified speed, duplex, pause mode, and phy interface
-	 *   mode in the provided @state.
+ *   Configure the specified @state->speed, @state->duplex and
+ *   @state->pause (%MLO_PAUSE_TX / %MLO_PAUSE_RX) mode.
+ *
  * %MLO_AN_INBAND:
-	 *   place the link in an inband negotiation mode (such as
-	 *   1000base-X or Cisco SGMII mode depending on the phy interface
-	 *   mode), advertising the parameters given in advertising in @state.
+ *   place the link in an inband negotiation mode (such as 802.3z
+ *   1000base-X or Cisco SGMII mode depending on the @state->interface
+ *   mode). In both cases, link state management (whether the link
+ *   is up or not) is performed by the MAC, and reported via the
+ *   mac_link_state() callback. Changes in link state must be made
+ *   by calling phylink_mac_change().
+ *
+ *   If in 802.3z mode, the link speed is fixed, dependent on the
+ *   @state->interface. Duplex is negotiated, and pause is advertised
+ *   according to @state->an_enabled, @state->pause and
+ *   @state->advertising flags. Beware of MACs which only support full
+ *   duplex at gigabit and higher speeds.
+ *
+ *   If in Cisco SGMII mode, the link speed and duplex mode are passed
+ *   in the serial bitstream 16-bit configuration word, and the MAC
+ *   should be configured to read these bits and acknowledge the
+ *   configuration word. Nothing is advertised by the MAC. The MAC is
+ *   responsible for reading the configuration word and configuring
+ *   itself accordingly.
  */
-	void (*mac_config)(struct net_device *ndev, unsigned int mode,
+void mac_config(struct net_device *ndev, unsigned int mode,
 		const struct phylink_link_state *state);
 
-	/**
-	 * mac_an_restart: restart 802.3z BaseX autonegotiation
-	 * @ndev: net_device structure for the MAC
+/**
+ * mac_an_restart() - restart 802.3z BaseX autonegotiation
+ * @ndev: a pointer to a &struct net_device for the MAC.
  */
-	void (*mac_an_restart)(struct net_device *ndev);
+void mac_an_restart(struct net_device *ndev);
 
-	void (*mac_link_down)(struct net_device *, unsigned int mode);
-	void (*mac_link_up)(struct net_device *, unsigned int mode,
-			    struct phy_device *);
-};
+/**
+ * mac_link_down() - take the link down
+ * @ndev: a pointer to a &struct net_device for the MAC.
+ * @mode: link autonegotiation mode
+ *
+ * If @mode is not an in-band negotiation mode (as defined by
+ * phylink_autoneg_inband()), force the link down and disable any
+ * Energy Efficient Ethernet MAC configuration.
+ */
+void mac_link_down(struct net_device *ndev, unsigned int mode);
+
+/**
+ * mac_link_up() - allow the link to come up
+ * @ndev: a pointer to a &struct net_device for the MAC.
+ * @mode: link autonegotiation mode
+ * @phy: any attached phy
+ *
+ * If @mode is not an in-band negotiation mode (as defined by
+ * phylink_autoneg_inband()), allow the link to come up. If @phy
+ * is non-%NULL, configure Energy Efficient Ethernet by calling
+ * phy_init_eee() and perform appropriate MAC configuration for EEE.
+ */
+void mac_link_up(struct net_device *ndev, unsigned int mode,
+		 struct phy_device *phy);
+#endif
 
 struct phylink *phylink_create(struct net_device *, struct device_node *,
 	phy_interface_t iface, const struct phylink_mac_ops *ops);