Merge branch 'net-add-negotiation-of-in-band-capabilities'

Russell King says:

====================
net: add negotiation of in-band capabilities

This is a repost without RFC for this series, shrunk down to 13 patches
by removing the non-Marvell PCS.

Phylink's handling of in-band has been deficient for a long time, and
people keep hitting problems with it. Notably, situations with the way-
to-late standardized 2500Base-X and whether that should or should not
have in-band enabled. We have also been carrying a hack in the form of
phylink_phy_no_inband() for a PHY that has been used on a SFP module,
but has no in-band capabilities, not even for SGMII.

When phylink is trying to operate in in-band mode, this series will look
at the capabilities of the MAC-side PCS and PHY, and work out whether
in-band can or should be used, programming the PHY as appropriate. This
includes in-band bypass mode at the PHY.

We don't... yet... support bypass on the MAC side PCS, because that
requires yet more complexity.

Patch 1 passes struct phylink and struct phylink_pcs into
phylink_pcs_neg_mode() so we can look at more state in this function in
a future patch.

Patch 2 splits "cur_link_an_mode" (the MLO_AN_* mode) into two separate
purposes - a requested and an active mode. The active mode is the one
we will be using for the MAC, which becomes dependent on the result of
in-band negotiation.

Patch 3 adds debug to phylink_major_config() so we can see what is going
on with the requested and active AN modes.

Patch 4 adds to phylib a method to get the in-band capabilities of the
PHY from phylib. Patches 5 and 6 add implementations for BCM84881 and
some Marvell PHYs found on SFPs.

Patch 7 adds to phylib a method to configure the PHY in-band signalling,
and patch 8 implements it for those Marvell PHYs that support the method
in patch 4.

Patch 9 does the same as patch 4 but for the MAC-side PCS, with patches
10 and 11 adding support to Marvell NETA and PP2.

Patch 12 adds the code to phylink_pcs_neg_mode() which looks at the
capabilities, and works out whether to use in-band or out-band mode for
driving the link between the MAC PCS and PHY.

Patch 13 removes the phylink_phy_no_inband() hack now that we are
publishing the in-band capabilities from the BCM84881 PHY driver.

Three more PCS, omitted from this series due to the limit of 15 patches,
will be sent once this has been merged.
====================

Link: https://patch.msgid.link/Z08kCwxdkU4n2V6x@shell.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 51 insertions, 0 deletions

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 563c46205685..61a1bc81f597 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -818,6 +818,24 @@ struct phy_tdr_config {
 #define PHY_PAIR_ALL -1
 
 /**
+ * enum link_inband_signalling - in-band signalling modes that are supported
+ *
+ * @LINK_INBAND_DISABLE: in-band signalling can be disabled
+ * @LINK_INBAND_ENABLE: in-band signalling can be enabled without bypass
+ * @LINK_INBAND_BYPASS: in-band signalling can be enabled with bypass
+ *
+ * The possible and required bits can only be used if the valid bit is set.
+ * If possible is clear, that means inband signalling can not be used.
+ * Required is only valid when possible is set, and means that inband
+ * signalling must be used.
+ */
+enum link_inband_signalling {
+	LINK_INBAND_DISABLE		= BIT(0),
+	LINK_INBAND_ENABLE		= BIT(1),
+	LINK_INBAND_BYPASS		= BIT(2),
+};
+
+/**
  * struct phy_plca_cfg - Configuration of the PLCA (Physical Layer Collision
  * Avoidance) Reconciliation Sublayer.
  *
@@ -957,6 +975,19 @@ struct phy_driver {
 	int (*get_features)(struct phy_device *phydev);
 
 	/**
+	 * @inband_caps: query whether in-band is supported for the given PHY
+	 * interface mode. Returns a bitmask of bits defined by enum
+	 * link_inband_signalling.
+	 */
+	unsigned int (*inband_caps)(struct phy_device *phydev,
+				    phy_interface_t interface);
+
+	/**
+	 * @config_inband: configure in-band mode for the PHY
+	 */
+	int (*config_inband)(struct phy_device *phydev, unsigned int modes);
+
+	/**
 	 * @get_rate_matching: Get the supported type of rate matching for a
 	 * particular phy interface. This is used by phy consumers to determine
 	 * whether to advertise lower-speed modes for that interface. It is
@@ -1818,6 +1849,9 @@ int phy_config_aneg(struct phy_device *phydev);
 int _phy_start_aneg(struct phy_device *phydev);
 int phy_start_aneg(struct phy_device *phydev);
 int phy_aneg_done(struct phy_device *phydev);
+unsigned int phy_inband_caps(struct phy_device *phydev,
+			     phy_interface_t interface);
+int phy_config_inband(struct phy_device *phydev, unsigned int modes);
 int phy_speed_down(struct phy_device *phydev, bool sync);
 int phy_speed_up(struct phy_device *phydev);
 bool phy_check_valid(int speed, int duplex, unsigned long *features);
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 5c01048860c4..5462cc6a37dc 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -419,6 +419,7 @@ struct phylink_pcs {
 /**
  * struct phylink_pcs_ops - MAC PCS operations structure.
  * @pcs_validate: validate the link configuration.
+ * @pcs_inband_caps: query inband support for interface mode.
  * @pcs_enable: enable the PCS.
  * @pcs_disable: disable the PCS.
  * @pcs_pre_config: pre-mac_config method (for errata)
@@ -434,6 +435,8 @@ struct phylink_pcs {
 struct phylink_pcs_ops {
 	int (*pcs_validate)(struct phylink_pcs *pcs, unsigned long *supported,
 			    const struct phylink_link_state *state);
+	unsigned int (*pcs_inband_caps)(struct phylink_pcs *pcs,
+					phy_interface_t interface);
 	int (*pcs_enable)(struct phylink_pcs *pcs);
 	void (*pcs_disable)(struct phylink_pcs *pcs);
 	void (*pcs_pre_config)(struct phylink_pcs *pcs,
@@ -471,6 +474,20 @@ int pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
 		 const struct phylink_link_state *state);
 
 /**
+ * pcs_inband_caps - query PCS in-band capabilities for interface mode.
+ * @pcs: a pointer to a &struct phylink_pcs.
+ * @interface: interface mode to be queried
+ *
+ * Returns zero if it is unknown what in-band signalling is supported by the
+ * PHY (e.g. because the PHY driver doesn't implement the method.) Otherwise,
+ * returns a bit mask of the LINK_INBAND_* values from
+ * &enum link_inband_signalling to describe which inband modes are supported
+ * for this interface mode.
+ */
+unsigned int pcs_inband_caps(struct phylink_pcs *pcs,
+			     phy_interface_t interface);
+
+/**
  * pcs_enable() - enable the PCS.
  * @pcs: a pointer to a &struct phylink_pcs.
  */