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>

drivers/net/ethernet/marvell/mvneta.c

@@ -3960,20 +3960,27 @@ static struct mvneta_port *mvneta_pcs_to_port(struct phylink_pcs *pcs)
 	return container_of(pcs, struct mvneta_port, phylink_pcs);
 }
 
-static int mvneta_pcs_validate(struct phylink_pcs *pcs,
-			       unsigned long *supported,
-			       const struct phylink_link_state *state)
+static unsigned int mvneta_pcs_inband_caps(struct phylink_pcs *pcs,
+					   phy_interface_t interface)
 {
-	/* We only support QSGMII, SGMII, 802.3z and RGMII modes.
-	 * When in 802.3z mode, we must have AN enabled:
+	/* When operating in an 802.3z mode, we must have AN enabled:
 	 * "Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
 	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1."
+	 * Therefore, inband is "required".
 	 */
-	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg))
-		return -EINVAL;
+	if (phy_interface_mode_is_8023z(interface))
+		return LINK_INBAND_ENABLE;
 
-	return 0;
+	/* QSGMII, SGMII and RGMII can be configured to use inband
+	 * signalling of the AN result. Indicate these as "possible".
+	 */
+	if (interface == PHY_INTERFACE_MODE_SGMII ||
+	    interface == PHY_INTERFACE_MODE_QSGMII ||
+	    phy_interface_mode_is_rgmii(interface))
+		return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE;
+
+	/* For any other modes, indicate that inband is not supported. */
+	return LINK_INBAND_DISABLE;
 }
 
 static void mvneta_pcs_get_state(struct phylink_pcs *pcs,
@@ -4071,7 +4078,7 @@ static void mvneta_pcs_an_restart(struct phylink_pcs *pcs)
 }
 
 static const struct phylink_pcs_ops mvneta_phylink_pcs_ops = {
-	.pcs_validate = mvneta_pcs_validate,
+	.pcs_inband_caps = mvneta_pcs_inband_caps,
 	.pcs_get_state = mvneta_pcs_get_state,
 	.pcs_config = mvneta_pcs_config,
 	.pcs_an_restart = mvneta_pcs_an_restart,

drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c

@@ -6224,19 +6224,26 @@ static const struct phylink_pcs_ops mvpp2_phylink_xlg_pcs_ops = {
 	.pcs_config = mvpp2_xlg_pcs_config,
 };
 
-static int mvpp2_gmac_pcs_validate(struct phylink_pcs *pcs,
-				   unsigned long *supported,
-				   const struct phylink_link_state *state)
+static unsigned int mvpp2_gmac_pcs_inband_caps(struct phylink_pcs *pcs,
+					       phy_interface_t interface)
 {
-	/* When in 802.3z mode, we must have AN enabled:
+	/* When operating in an 802.3z mode, we must have AN enabled:
 	 * Bit 2 Field InBandAnEn In-band Auto-Negotiation enable. ...
 	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1.
+	 * Therefore, inband is "required".
 	 */
-	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg))
-		return -EINVAL;
+	if (phy_interface_mode_is_8023z(interface))
+		return LINK_INBAND_ENABLE;
 
-	return 0;
+	/* SGMII and RGMII can be configured to use inband signalling of the
+	 * AN result. Indicate these as "possible".
+	 */
+	if (interface == PHY_INTERFACE_MODE_SGMII ||
+	    phy_interface_mode_is_rgmii(interface))
+		return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE;
+
+	/* For any other modes, indicate that inband is not supported. */
+	return LINK_INBAND_DISABLE;
 }
 
 static void mvpp2_gmac_pcs_get_state(struct phylink_pcs *pcs,
@@ -6343,7 +6350,7 @@ static void mvpp2_gmac_pcs_an_restart(struct phylink_pcs *pcs)
 }
 
 static const struct phylink_pcs_ops mvpp2_phylink_gmac_pcs_ops = {
-	.pcs_validate = mvpp2_gmac_pcs_validate,
+	.pcs_inband_caps = mvpp2_gmac_pcs_inband_caps,
 	.pcs_get_state = mvpp2_gmac_pcs_get_state,
 	.pcs_config = mvpp2_gmac_pcs_config,
 	.pcs_an_restart = mvpp2_gmac_pcs_an_restart,

drivers/net/phy/bcm84881.c

@@ -235,11 +235,21 @@ static int bcm84881_read_status(struct phy_device *phydev)
 	return genphy_c45_read_mdix(phydev);
 }
 
+/* The Broadcom BCM84881 in the Methode DM7052 is unable to provide a SGMII
+ * or 802.3z control word, so inband will not work.
+ */
+static unsigned int bcm84881_inband_caps(struct phy_device *phydev,
+					 phy_interface_t interface)
+{
+	return LINK_INBAND_DISABLE;
+}
+
 static struct phy_driver bcm84881_drivers[] = {
 	{
 		.phy_id		= 0xae025150,
 		.phy_id_mask	= 0xfffffff0,
 		.name		= "Broadcom BCM84881",
+		.inband_caps	= bcm84881_inband_caps,
 		.config_init	= bcm84881_config_init,
 		.probe		= bcm84881_probe,
 		.get_features	= bcm84881_get_features,

drivers/net/phy/marvell.c

@@ -717,6 +717,48 @@ static int marvell_config_aneg_fiber(struct phy_device *phydev)
 	return genphy_check_and_restart_aneg(phydev, changed);
 }
 
+static unsigned int m88e1111_inband_caps(struct phy_device *phydev,
+					 phy_interface_t interface)
+{
+	/* In 1000base-X and SGMII modes, the inband mode can be changed
+	 * through the Fibre page BMCR ANENABLE bit.
+	 */
+	if (interface == PHY_INTERFACE_MODE_1000BASEX ||
+	    interface == PHY_INTERFACE_MODE_SGMII)
+		return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE |
+		       LINK_INBAND_BYPASS;
+
+	return 0;
+}
+
+static int m88e1111_config_inband(struct phy_device *phydev, unsigned int modes)
+{
+	u16 extsr, bmcr;
+	int err;
+
+	if (phydev->interface != PHY_INTERFACE_MODE_1000BASEX &&
+	    phydev->interface != PHY_INTERFACE_MODE_SGMII)
+		return -EINVAL;
+
+	if (modes == LINK_INBAND_BYPASS)
+		extsr = MII_M1111_HWCFG_SERIAL_AN_BYPASS;
+	else
+		extsr = 0;
+
+	if (modes == LINK_INBAND_DISABLE)
+		bmcr = 0;
+	else
+		bmcr = BMCR_ANENABLE;
+
+	err = phy_modify(phydev, MII_M1111_PHY_EXT_SR,
+			 MII_M1111_HWCFG_SERIAL_AN_BYPASS, extsr);
+	if (err < 0)
+		return extsr;
+
+	return phy_modify_paged(phydev, MII_MARVELL_FIBER_PAGE, MII_BMCR,
+				BMCR_ANENABLE, bmcr);
+}
+
 static int m88e1111_config_aneg(struct phy_device *phydev)
 {
 	int extsr = phy_read(phydev, MII_M1111_PHY_EXT_SR);
@@ -3677,6 +3719,8 @@ static struct phy_driver marvell_drivers[] = {
 		.name = "Marvell 88E1112",
 		/* PHY_GBIT_FEATURES */
 		.probe = marvell_probe,
+		.inband_caps = m88e1111_inband_caps,
+		.config_inband = m88e1111_config_inband,
 		.config_init = m88e1112_config_init,
 		.config_aneg = marvell_config_aneg,
 		.config_intr = marvell_config_intr,
@@ -3698,6 +3742,8 @@ static struct phy_driver marvell_drivers[] = {
 		/* PHY_GBIT_FEATURES */
 		.flags = PHY_POLL_CABLE_TEST,
 		.probe = marvell_probe,
+		.inband_caps = m88e1111_inband_caps,
+		.config_inband = m88e1111_config_inband,
 		.config_init = m88e1111gbe_config_init,
 		.config_aneg = m88e1111_config_aneg,
 		.read_status = marvell_read_status,
@@ -3721,6 +3767,8 @@ static struct phy_driver marvell_drivers[] = {
 		.name = "Marvell 88E1111 (Finisar)",
 		/* PHY_GBIT_FEATURES */
 		.probe = marvell_probe,
+		.inband_caps = m88e1111_inband_caps,
+		.config_inband = m88e1111_config_inband,
 		.config_init = m88e1111gbe_config_init,
 		.config_aneg = m88e1111_config_aneg,
 		.read_status = marvell_read_status,

drivers/net/phy/phy.c

@@ -1005,6 +1005,59 @@ static int phy_check_link_status(struct phy_device *phydev)
 	return 0;
 }
 
+/**
+ * phy_inband_caps - query which in-band signalling modes are supported
+ * @phydev: a pointer to a &struct phy_device
+ * @interface: the interface mode for the PHY
+ *
+ * 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
+ * by the PHY for this interface mode.
+ */
+unsigned int phy_inband_caps(struct phy_device *phydev,
+			     phy_interface_t interface)
+{
+	if (phydev->drv && phydev->drv->inband_caps)
+		return phydev->drv->inband_caps(phydev, interface);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(phy_inband_caps);
+
+/**
+ * phy_config_inband - configure the desired PHY in-band mode
+ * @phydev: the phy_device struct
+ * @modes: in-band modes to configure
+ *
+ * Description: disables, enables or enables-with-bypass in-band signalling
+ *   between the PHY and host system.
+ *
+ * Returns: zero on success, or negative errno value.
+ */
+int phy_config_inband(struct phy_device *phydev, unsigned int modes)
+{
+	int err;
+
+	if (!!(modes & LINK_INBAND_DISABLE) +
+	    !!(modes & LINK_INBAND_ENABLE) +
+	    !!(modes & LINK_INBAND_BYPASS) != 1)
+		return -EINVAL;
+
+	mutex_lock(&phydev->lock);
+	if (!phydev->drv)
+		err = -EIO;
+	else if (!phydev->drv->config_inband)
+		err = -EOPNOTSUPP;
+	else
+		err = phydev->drv->config_inband(phydev, modes);
+	mutex_unlock(&phydev->lock);
+
+	return err;
+}
+EXPORT_SYMBOL(phy_config_inband);
+
 /**
  * _phy_start_aneg - start auto-negotiation for this PHY device
  * @phydev: the phy_device struct