Merge branch 'phylink-pcs-validation'

Russell King says:

====================
net: phylink: add PCS validation

This series allows phylink to include the PCS in its validation step.
There are two reasons to make this change:

1. Some of the network drivers that are making use of the split PCS
   support are already manually calling into their PCS drivers to
   perform validation. E.g. stmmac with xpcs.

2. Logically, some network drivers such as mvneta and mvpp2, the
   restriction we impose in the validate() callback is a property of
   the "PCS" block that we provide rather than the MAC.

This series:

1. Gives phylink a mechanism to query the MAC driver which PCS is
   wishes to use for the PHY interface mode. This is necessary to allow
   the PCS to be involved in the validation step without making changes
   to the configuration.

2. Provide a pcs_validate() method that PCS can implement. This follows
   a similar model to the MAC's validate() callback, but with some minor
   differences due to observations from the various implementations.
   E.g. returning an error code for not-supported and the way the
   advertising bitmap is masked.

3. Convert mvpp2 and mvneta to this as examples of its use. Further
   Conversions are in the pipeline, including for stmmac+xpcs, as well
   as some DSA drivers. Note that DSA conversion to this is conditional
   upon all DSA drivers populating their supported_interfaces bitmap,
   since this is required before mac_select_pcs() can be used.

Existing drivers that set a PCS in mac_prepare() or mac_config(), or
shortly after phylink_create() will continue to work. However, it should
be noted that mac_select_pcs() will be called during phylink_create(),
and thus any PCS returned by mac_select_pcs() must be available by this
time - or we drop the check in phylink_create().

v2: fix kerneldoc typo in patch 1.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 337 insertions, 144 deletions

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index e3c5d64ba340..e4c328f61188 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -526,6 +526,7 @@ struct mvneta_port {
 	unsigned int tx_csum_limit;
 	struct phylink *phylink;
 	struct phylink_config phylink_config;
+	struct phylink_pcs phylink_pcs;
 	struct phy *comphy;
 
 	struct mvneta_bm *bm_priv;
@@ -3846,9 +3847,14 @@ static int mvneta_set_mac_addr(struct net_device *dev, void *addr)
 	return 0;
 }
 
-static void mvneta_validate(struct phylink_config *config,
-			    unsigned long *supported,
-			    struct phylink_link_state *state)
+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)
 {
 	/* We only support QSGMII, SGMII, 802.3z and RGMII modes.
 	 * When in 802.3z mode, we must have AN enabled:
@@ -3856,19 +3862,16 @@ static void mvneta_validate(struct phylink_config *config,
 	 * When <PortType> = 1 (1000BASE-X) this field must be set to 1."
 	 */
 	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg)) {
-		linkmode_zero(supported);
-		return;
-	}
+	    !phylink_test(state->advertising, Autoneg))
+		return -EINVAL;
 
-	phylink_generic_validate(config, supported, state);
+	return 0;
 }
 
-static void mvneta_mac_pcs_get_state(struct phylink_config *config,
-				     struct phylink_link_state *state)
+static void mvneta_pcs_get_state(struct phylink_pcs *pcs,
+				 struct phylink_link_state *state)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct mvneta_port *pp = netdev_priv(ndev);
+	struct mvneta_port *pp = mvneta_pcs_to_port(pcs);
 	u32 gmac_stat;
 
 	gmac_stat = mvreg_read(pp, MVNETA_GMAC_STATUS);
@@ -3886,17 +3889,71 @@ static void mvneta_mac_pcs_get_state(struct phylink_config *config,
 	state->link = !!(gmac_stat & MVNETA_GMAC_LINK_UP);
 	state->duplex = !!(gmac_stat & MVNETA_GMAC_FULL_DUPLEX);
 
-	state->pause = 0;
 	if (gmac_stat & MVNETA_GMAC_RX_FLOW_CTRL_ENABLE)
 		state->pause |= MLO_PAUSE_RX;
 	if (gmac_stat & MVNETA_GMAC_TX_FLOW_CTRL_ENABLE)
 		state->pause |= MLO_PAUSE_TX;
 }
 
-static void mvneta_mac_an_restart(struct phylink_config *config)
+static int mvneta_pcs_config(struct phylink_pcs *pcs,
+			     unsigned int mode, phy_interface_t interface,
+			     const unsigned long *advertising,
+			     bool permit_pause_to_mac)
 {
-	struct net_device *ndev = to_net_dev(config->dev);
-	struct mvneta_port *pp = netdev_priv(ndev);
+	struct mvneta_port *pp = mvneta_pcs_to_port(pcs);
+	u32 mask, val, an, old_an, changed;
+
+	mask = MVNETA_GMAC_INBAND_AN_ENABLE |
+	       MVNETA_GMAC_INBAND_RESTART_AN |
+	       MVNETA_GMAC_AN_SPEED_EN |
+	       MVNETA_GMAC_AN_FLOW_CTRL_EN |
+	       MVNETA_GMAC_AN_DUPLEX_EN;
+
+	if (phylink_autoneg_inband(mode)) {
+		mask |= MVNETA_GMAC_CONFIG_MII_SPEED |
+			MVNETA_GMAC_CONFIG_GMII_SPEED |
+			MVNETA_GMAC_CONFIG_FULL_DUPLEX;
+		val = MVNETA_GMAC_INBAND_AN_ENABLE;
+
+		if (interface == PHY_INTERFACE_MODE_SGMII) {
+			/* SGMII mode receives the speed and duplex from PHY */
+			val |= MVNETA_GMAC_AN_SPEED_EN |
+			       MVNETA_GMAC_AN_DUPLEX_EN;
+		} else {
+			/* 802.3z mode has fixed speed and duplex */
+			val |= MVNETA_GMAC_CONFIG_GMII_SPEED |
+			       MVNETA_GMAC_CONFIG_FULL_DUPLEX;
+
+			/* The FLOW_CTRL_EN bit selects either the hardware
+			 * automatically or the CONFIG_FLOW_CTRL manually
+			 * controls the GMAC pause mode.
+			 */
+			if (permit_pause_to_mac)
+				val |= MVNETA_GMAC_AN_FLOW_CTRL_EN;
+
+			/* Update the advertisement bits */
+			mask |= MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL;
+			if (phylink_test(advertising, Pause))
+				val |= MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL;
+		}
+	} else {
+		/* Phy or fixed speed - disable in-band AN modes */
+		val = 0;
+	}
+
+	old_an = an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
+	an = (an & ~mask) | val;
+	changed = old_an ^ an;
+	if (changed)
+		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, an);
+
+	/* We are only interested in the advertisement bits changing */
+	return !!(changed & MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL);
+}
+
+static void mvneta_pcs_an_restart(struct phylink_pcs *pcs)
+{
+	struct mvneta_port *pp = mvneta_pcs_to_port(pcs);
 	u32 gmac_an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
 
 	mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG,
@@ -3905,6 +3962,47 @@ static void mvneta_mac_an_restart(struct phylink_config *config)
 		    gmac_an & ~MVNETA_GMAC_INBAND_RESTART_AN);
 }
 
+static const struct phylink_pcs_ops mvneta_phylink_pcs_ops = {
+	.pcs_validate = mvneta_pcs_validate,
+	.pcs_get_state = mvneta_pcs_get_state,
+	.pcs_config = mvneta_pcs_config,
+	.pcs_an_restart = mvneta_pcs_an_restart,
+};
+
+static int mvneta_mac_prepare(struct phylink_config *config, unsigned int mode,
+			      phy_interface_t interface)
+{
+	struct net_device *ndev = to_net_dev(config->dev);
+	struct mvneta_port *pp = netdev_priv(ndev);
+	u32 val;
+
+	if (pp->phy_interface != interface ||
+	    phylink_autoneg_inband(mode)) {
+		/* Force the link down when changing the interface or if in
+		 * in-band mode. According to Armada 370 documentation, we
+		 * can only change the port mode and in-band enable when the
+		 * link is down.
+		 */
+		val = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
+		val &= ~MVNETA_GMAC_FORCE_LINK_PASS;
+		val |= MVNETA_GMAC_FORCE_LINK_DOWN;
+		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, val);
+	}
+
+	if (pp->phy_interface != interface)
+		WARN_ON(phy_power_off(pp->comphy));
+
+	/* Enable the 1ms clock */
+	if (phylink_autoneg_inband(mode)) {
+		unsigned long rate = clk_get_rate(pp->clk);
+
+		mvreg_write(pp, MVNETA_GMAC_CLOCK_DIVIDER,
+			    MVNETA_GMAC_1MS_CLOCK_ENABLE | (rate / 1000));
+	}
+
+	return 0;
+}
+
 static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 			      const struct phylink_link_state *state)
 {
@@ -3913,20 +4011,11 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	u32 new_ctrl0, gmac_ctrl0 = mvreg_read(pp, MVNETA_GMAC_CTRL_0);
 	u32 new_ctrl2, gmac_ctrl2 = mvreg_read(pp, MVNETA_GMAC_CTRL_2);
 	u32 new_ctrl4, gmac_ctrl4 = mvreg_read(pp, MVNETA_GMAC_CTRL_4);
-	u32 new_clk, gmac_clk = mvreg_read(pp, MVNETA_GMAC_CLOCK_DIVIDER);
-	u32 new_an, gmac_an = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
 
 	new_ctrl0 = gmac_ctrl0 & ~MVNETA_GMAC0_PORT_1000BASE_X;
 	new_ctrl2 = gmac_ctrl2 & ~(MVNETA_GMAC2_INBAND_AN_ENABLE |
 				   MVNETA_GMAC2_PORT_RESET);
 	new_ctrl4 = gmac_ctrl4 & ~(MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE);
-	new_clk = gmac_clk & ~MVNETA_GMAC_1MS_CLOCK_ENABLE;
-	new_an = gmac_an & ~(MVNETA_GMAC_INBAND_AN_ENABLE |
-			     MVNETA_GMAC_INBAND_RESTART_AN |
-			     MVNETA_GMAC_AN_SPEED_EN |
-			     MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL |
-			     MVNETA_GMAC_AN_FLOW_CTRL_EN |
-			     MVNETA_GMAC_AN_DUPLEX_EN);
 
 	/* Even though it might look weird, when we're configured in
 	 * SGMII or QSGMII mode, the RGMII bit needs to be set.
@@ -3938,9 +4027,6 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	    phy_interface_mode_is_8023z(state->interface))
 		new_ctrl2 |= MVNETA_GMAC2_PCS_ENABLE;
 
-	if (phylink_test(state->advertising, Pause))
-		new_an |= MVNETA_GMAC_ADVERT_SYM_FLOW_CTRL;
-
 	if (!phylink_autoneg_inband(mode)) {
 		/* Phy or fixed speed - nothing to do, leave the
 		 * configured speed, duplex and flow control as-is.
@@ -3948,70 +4034,23 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	} else if (state->interface == PHY_INTERFACE_MODE_SGMII) {
 		/* SGMII mode receives the state from the PHY */
 		new_ctrl2 |= MVNETA_GMAC2_INBAND_AN_ENABLE;
-		new_clk = MVNETA_GMAC_1MS_CLOCK_ENABLE;
-		new_an = (new_an & ~(MVNETA_GMAC_FORCE_LINK_DOWN |
-				     MVNETA_GMAC_FORCE_LINK_PASS |
-				     MVNETA_GMAC_CONFIG_MII_SPEED |
-				     MVNETA_GMAC_CONFIG_GMII_SPEED |
-				     MVNETA_GMAC_CONFIG_FULL_DUPLEX)) |
-			 MVNETA_GMAC_INBAND_AN_ENABLE |
-			 MVNETA_GMAC_AN_SPEED_EN |
-			 MVNETA_GMAC_AN_DUPLEX_EN;
 	} else {
 		/* 802.3z negotiation - only 1000base-X */
 		new_ctrl0 |= MVNETA_GMAC0_PORT_1000BASE_X;
-		new_clk = MVNETA_GMAC_1MS_CLOCK_ENABLE;
-		new_an = (new_an & ~(MVNETA_GMAC_FORCE_LINK_DOWN |
-				     MVNETA_GMAC_FORCE_LINK_PASS |
-				     MVNETA_GMAC_CONFIG_MII_SPEED)) |
-			 MVNETA_GMAC_INBAND_AN_ENABLE |
-			 MVNETA_GMAC_CONFIG_GMII_SPEED |
-			 /* The MAC only supports FD mode */
-			 MVNETA_GMAC_CONFIG_FULL_DUPLEX;
-
-		if (state->pause & MLO_PAUSE_AN && state->an_enabled)
-			new_an |= MVNETA_GMAC_AN_FLOW_CTRL_EN;
 	}
 
-	/* Set the 1ms clock divisor */
-	if (new_clk == MVNETA_GMAC_1MS_CLOCK_ENABLE)
-		new_clk |= clk_get_rate(pp->clk) / 1000;
-
-	/* Armada 370 documentation says we can only change the port mode
-	 * and in-band enable when the link is down, so force it down
-	 * while making these changes. We also do this for GMAC_CTRL2
-	 */
-	if ((new_ctrl0 ^ gmac_ctrl0) & MVNETA_GMAC0_PORT_1000BASE_X ||
-	    (new_ctrl2 ^ gmac_ctrl2) & MVNETA_GMAC2_INBAND_AN_ENABLE ||
-	    (new_an  ^ gmac_an) & MVNETA_GMAC_INBAND_AN_ENABLE) {
-		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG,
-			    (gmac_an & ~MVNETA_GMAC_FORCE_LINK_PASS) |
-			    MVNETA_GMAC_FORCE_LINK_DOWN);
-	}
-
-
 	/* When at 2.5G, the link partner can send frames with shortened
 	 * preambles.
 	 */
 	if (state->interface == PHY_INTERFACE_MODE_2500BASEX)
 		new_ctrl4 |= MVNETA_GMAC4_SHORT_PREAMBLE_ENABLE;
 
-	if (pp->phy_interface != state->interface) {
-		if (pp->comphy)
-			WARN_ON(phy_power_off(pp->comphy));
-		WARN_ON(mvneta_config_interface(pp, state->interface));
-	}
-
 	if (new_ctrl0 != gmac_ctrl0)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_0, new_ctrl0);
 	if (new_ctrl2 != gmac_ctrl2)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_2, new_ctrl2);
 	if (new_ctrl4 != gmac_ctrl4)
 		mvreg_write(pp, MVNETA_GMAC_CTRL_4, new_ctrl4);
-	if (new_clk != gmac_clk)
-		mvreg_write(pp, MVNETA_GMAC_CLOCK_DIVIDER, new_clk);
-	if (new_an != gmac_an)
-		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, new_an);
 
 	if (gmac_ctrl2 & MVNETA_GMAC2_PORT_RESET) {
 		while ((mvreg_read(pp, MVNETA_GMAC_CTRL_2) &
@@ -4020,6 +4059,36 @@ static void mvneta_mac_config(struct phylink_config *config, unsigned int mode,
 	}
 }
 
+static int mvneta_mac_finish(struct phylink_config *config, unsigned int mode,
+			     phy_interface_t interface)
+{
+	struct net_device *ndev = to_net_dev(config->dev);
+	struct mvneta_port *pp = netdev_priv(ndev);
+	u32 val, clk;
+
+	/* Disable 1ms clock if not in in-band mode */
+	if (!phylink_autoneg_inband(mode)) {
+		clk = mvreg_read(pp, MVNETA_GMAC_CLOCK_DIVIDER);
+		clk &= ~MVNETA_GMAC_1MS_CLOCK_ENABLE;
+		mvreg_write(pp, MVNETA_GMAC_CLOCK_DIVIDER, clk);
+	}
+
+	if (pp->phy_interface != interface)
+		/* Enable the Serdes PHY */
+		WARN_ON(mvneta_config_interface(pp, interface));
+
+	/* Allow the link to come up if in in-band mode, otherwise the
+	 * link is forced via mac_link_down()/mac_link_up()
+	 */
+	if (phylink_autoneg_inband(mode)) {
+		val = mvreg_read(pp, MVNETA_GMAC_AUTONEG_CONFIG);
+		val &= ~MVNETA_GMAC_FORCE_LINK_DOWN;
+		mvreg_write(pp, MVNETA_GMAC_AUTONEG_CONFIG, val);
+	}
+
+	return 0;
+}
+
 static void mvneta_set_eee(struct mvneta_port *pp, bool enable)
 {
 	u32 lpi_ctl1;
@@ -4106,10 +4175,10 @@ static void mvneta_mac_link_up(struct phylink_config *config,
 }
 
 static const struct phylink_mac_ops mvneta_phylink_ops = {
-	.validate = mvneta_validate,
-	.mac_pcs_get_state = mvneta_mac_pcs_get_state,
-	.mac_an_restart = mvneta_mac_an_restart,
+	.validate = phylink_generic_validate,
+	.mac_prepare = mvneta_mac_prepare,
 	.mac_config = mvneta_mac_config,
+	.mac_finish = mvneta_mac_finish,
 	.mac_link_down = mvneta_mac_link_down,
 	.mac_link_up = mvneta_mac_link_up,
 };
@@ -5275,7 +5344,6 @@ static int mvneta_probe(struct platform_device *pdev)
 
 	pp->phylink_config.dev = &dev->dev;
 	pp->phylink_config.type = PHYLINK_NETDEV;
-	pp->phylink_config.legacy_pre_march2020 = true;
 	pp->phylink_config.mac_capabilities = MAC_SYM_PAUSE | MAC_10 |
 		MAC_100 | MAC_1000FD | MAC_2500FD;
 
@@ -5350,6 +5418,9 @@ static int mvneta_probe(struct platform_device *pdev)
 		goto err_clk;
 	}
 
+	pp->phylink_pcs.ops = &mvneta_phylink_pcs_ops;
+	phylink_set_pcs(phylink, &pp->phylink_pcs);
+
 	/* Alloc per-cpu port structure */
 	pp->ports = alloc_percpu(struct mvneta_pcpu_port);
 	if (!pp->ports) {
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
index cf8acabb90ac..ad73a488fc5f 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
@@ -1239,7 +1239,8 @@ struct mvpp2_port {
 	phy_interface_t phy_interface;
 	struct phylink *phylink;
 	struct phylink_config phylink_config;
-	struct phylink_pcs phylink_pcs;
+	struct phylink_pcs pcs_gmac;
+	struct phylink_pcs pcs_xlg;
 	struct phy *comphy;
 
 	struct mvpp2_bm_pool *pool_long;
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index b1cce4425296..339ae274021e 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -6115,15 +6115,20 @@ static struct mvpp2_port *mvpp2_phylink_to_port(struct phylink_config *config)
 	return container_of(config, struct mvpp2_port, phylink_config);
 }
 
-static struct mvpp2_port *mvpp2_pcs_to_port(struct phylink_pcs *pcs)
+static struct mvpp2_port *mvpp2_pcs_xlg_to_port(struct phylink_pcs *pcs)
 {
-	return container_of(pcs, struct mvpp2_port, phylink_pcs);
+	return container_of(pcs, struct mvpp2_port, pcs_xlg);
+}
+
+static struct mvpp2_port *mvpp2_pcs_gmac_to_port(struct phylink_pcs *pcs)
+{
+	return container_of(pcs, struct mvpp2_port, pcs_gmac);
 }
 
 static void mvpp2_xlg_pcs_get_state(struct phylink_pcs *pcs,
 				    struct phylink_link_state *state)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_xlg_to_port(pcs);
 	u32 val;
 
 	if (port->phy_interface == PHY_INTERFACE_MODE_5GBASER)
@@ -6158,10 +6163,25 @@ 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)
+{
+	/* When in 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.
+	 */
+	if (phy_interface_mode_is_8023z(state->interface) &&
+	    !phylink_test(state->advertising, Autoneg))
+		return -EINVAL;
+
+	return 0;
+}
+
 static void mvpp2_gmac_pcs_get_state(struct phylink_pcs *pcs,
 				     struct phylink_link_state *state)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_gmac_to_port(pcs);
 	u32 val;
 
 	val = readl(port->base + MVPP2_GMAC_STATUS0);
@@ -6198,7 +6218,7 @@ static int mvpp2_gmac_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 				 const unsigned long *advertising,
 				 bool permit_pause_to_mac)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_gmac_to_port(pcs);
 	u32 mask, val, an, old_an, changed;
 
 	mask = MVPP2_GMAC_IN_BAND_AUTONEG_BYPASS |
@@ -6252,7 +6272,7 @@ static int mvpp2_gmac_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 
 static void mvpp2_gmac_pcs_an_restart(struct phylink_pcs *pcs)
 {
-	struct mvpp2_port *port = mvpp2_pcs_to_port(pcs);
+	struct mvpp2_port *port = mvpp2_pcs_gmac_to_port(pcs);
 	u32 val = readl(port->base + MVPP2_GMAC_AUTONEG_CONFIG);
 
 	writel(val | MVPP2_GMAC_IN_BAND_RESTART_AN,
@@ -6262,30 +6282,12 @@ 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_get_state = mvpp2_gmac_pcs_get_state,
 	.pcs_config = mvpp2_gmac_pcs_config,
 	.pcs_an_restart = mvpp2_gmac_pcs_an_restart,
 };
 
-static void mvpp2_phylink_validate(struct phylink_config *config,
-				   unsigned long *supported,
-				   struct phylink_link_state *state)
-{
-	/* When in 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.
-	 */
-	if (phy_interface_mode_is_8023z(state->interface) &&
-	    !phylink_test(state->advertising, Autoneg))
-		goto empty_set;
-
-	phylink_generic_validate(config, supported, state);
-	return;
-
-empty_set:
-	linkmode_zero(supported);
-}
-
 static void mvpp2_xlg_config(struct mvpp2_port *port, unsigned int mode,
 			     const struct phylink_link_state *state)
 {
@@ -6365,8 +6367,23 @@ static void mvpp2_gmac_config(struct mvpp2_port *port, unsigned int mode,
 		writel(ctrl4, port->base + MVPP22_GMAC_CTRL_4_REG);
 }
 
-static int mvpp2__mac_prepare(struct phylink_config *config, unsigned int mode,
-			      phy_interface_t interface)
+static struct phylink_pcs *mvpp2_select_pcs(struct phylink_config *config,
+					    phy_interface_t interface)
+{
+	struct mvpp2_port *port = mvpp2_phylink_to_port(config);
+
+	/* Select the appropriate PCS operations depending on the
+	 * configured interface mode. We will only switch to a mode
+	 * that the validate() checks have already passed.
+	 */
+	if (mvpp2_is_xlg(interface))
+		return &port->pcs_xlg;
+	else
+		return &port->pcs_gmac;
+}
+
+static int mvpp2_mac_prepare(struct phylink_config *config, unsigned int mode,
+			     phy_interface_t interface)
 {
 	struct mvpp2_port *port = mvpp2_phylink_to_port(config);
 
@@ -6415,31 +6432,9 @@ static int mvpp2__mac_prepare(struct phylink_config *config, unsigned int mode,
 		}
 	}
 
-	/* Select the appropriate PCS operations depending on the
-	 * configured interface mode. We will only switch to a mode
-	 * that the validate() checks have already passed.
-	 */
-	if (mvpp2_is_xlg(interface))
-		port->phylink_pcs.ops = &mvpp2_phylink_xlg_pcs_ops;
-	else
-		port->phylink_pcs.ops = &mvpp2_phylink_gmac_pcs_ops;
-
 	return 0;
 }
 
-static int mvpp2_mac_prepare(struct phylink_config *config, unsigned int mode,
-			     phy_interface_t interface)
-{
-	struct mvpp2_port *port = mvpp2_phylink_to_port(config);
-	int ret;
-
-	ret = mvpp2__mac_prepare(config, mode, interface);
-	if (ret == 0)
-		phylink_set_pcs(port->phylink, &port->phylink_pcs);
-
-	return ret;
-}
-
 static void mvpp2_mac_config(struct phylink_config *config, unsigned int mode,
 			     const struct phylink_link_state *state)
 {
@@ -6610,7 +6605,8 @@ static void mvpp2_mac_link_down(struct phylink_config *config,
 }
 
 static const struct phylink_mac_ops mvpp2_phylink_ops = {
-	.validate = mvpp2_phylink_validate,
+	.validate = phylink_generic_validate,
+	.mac_select_pcs = mvpp2_select_pcs,
 	.mac_prepare = mvpp2_mac_prepare,
 	.mac_config = mvpp2_mac_config,
 	.mac_finish = mvpp2_mac_finish,
@@ -6628,12 +6624,15 @@ static void mvpp2_acpi_start(struct mvpp2_port *port)
 	struct phylink_link_state state = {
 		.interface = port->phy_interface,
 	};
-	mvpp2__mac_prepare(&port->phylink_config, MLO_AN_INBAND,
-			   port->phy_interface);
+	struct phylink_pcs *pcs;
+
+	pcs = mvpp2_select_pcs(&port->phylink_config, port->phy_interface);
+
+	mvpp2_mac_prepare(&port->phylink_config, MLO_AN_INBAND,
+			  port->phy_interface);
 	mvpp2_mac_config(&port->phylink_config, MLO_AN_INBAND, &state);
-	port->phylink_pcs.ops->pcs_config(&port->phylink_pcs, MLO_AN_INBAND,
-					  port->phy_interface,
-					  state.advertising, false);
+	pcs->ops->pcs_config(pcs, MLO_AN_INBAND, port->phy_interface,
+			     state.advertising, false);
 	mvpp2_mac_finish(&port->phylink_config, MLO_AN_INBAND,
 			 port->phy_interface);
 	mvpp2_mac_link_up(&port->phylink_config, NULL,
@@ -6941,6 +6940,9 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 				  port->phylink_config.supported_interfaces);
 		}
 
+		port->pcs_gmac.ops = &mvpp2_phylink_gmac_pcs_ops;
+		port->pcs_xlg.ops = &mvpp2_phylink_xlg_pcs_ops;
+
 		phylink = phylink_create(&port->phylink_config, port_fwnode,
 					 phy_mode, &mvpp2_phylink_ops);
 		if (IS_ERR(phylink)) {
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 20df8af3e201..420201858564 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -419,6 +419,54 @@ void phylink_generic_validate(struct phylink_config *config,
 }
 EXPORT_SYMBOL_GPL(phylink_generic_validate);
 
+static int phylink_validate_mac_and_pcs(struct phylink *pl,
+					unsigned long *supported,
+					struct phylink_link_state *state)
+{
+	struct phylink_pcs *pcs;
+	int ret;
+
+	/* Get the PCS for this interface mode */
+	if (pl->mac_ops->mac_select_pcs) {
+		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
+		if (IS_ERR(pcs))
+			return PTR_ERR(pcs);
+	} else {
+		pcs = pl->pcs;
+	}
+
+	if (pcs) {
+		/* The PCS, if present, must be setup before phylink_create()
+		 * has been called. If the ops is not initialised, print an
+		 * error and backtrace rather than oopsing the kernel.
+		 */
+		if (!pcs->ops) {
+			phylink_err(pl, "interface %s: uninitialised PCS\n",
+				    phy_modes(state->interface));
+			dump_stack();
+			return -EINVAL;
+		}
+
+		/* Validate the link parameters with the PCS */
+		if (pcs->ops->pcs_validate) {
+			ret = pcs->ops->pcs_validate(pcs, supported, state);
+			if (ret < 0 || phylink_is_empty_linkmode(supported))
+				return -EINVAL;
+
+			/* Ensure the advertising mask is a subset of the
+			 * supported mask.
+			 */
+			linkmode_and(state->advertising, state->advertising,
+				     supported);
+		}
+	}
+
+	/* Then validate the link parameters with the MAC */
+	pl->mac_ops->validate(pl->config, supported, state);
+
+	return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;
+}
+
 static int phylink_validate_any(struct phylink *pl, unsigned long *supported,
 				struct phylink_link_state *state)
 {
@@ -434,9 +482,10 @@ static int phylink_validate_any(struct phylink *pl, unsigned long *supported,
 
 			t = *state;
 			t.interface = intf;
-			pl->mac_ops->validate(pl->config, s, &t);
-			linkmode_or(all_s, all_s, s);
-			linkmode_or(all_adv, all_adv, t.advertising);
+			if (!phylink_validate_mac_and_pcs(pl, s, &t)) {
+				linkmode_or(all_s, all_s, s);
+				linkmode_or(all_adv, all_adv, t.advertising);
+			}
 		}
 	}
 
@@ -458,9 +507,7 @@ static int phylink_validate(struct phylink *pl, unsigned long *supported,
 			return -EINVAL;
 	}
 
-	pl->mac_ops->validate(pl->config, supported, state);
-
-	return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;
+	return phylink_validate_mac_and_pcs(pl, supported, state);
 }
 
 static int phylink_parse_fixedlink(struct phylink *pl,
@@ -750,10 +797,21 @@ static void phylink_mac_pcs_an_restart(struct phylink *pl)
 static void phylink_major_config(struct phylink *pl, bool restart,
 				  const struct phylink_link_state *state)
 {
+	struct phylink_pcs *pcs = NULL;
 	int err;
 
 	phylink_dbg(pl, "major config %s\n", phy_modes(state->interface));
 
+	if (pl->mac_ops->mac_select_pcs) {
+		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
+		if (IS_ERR(pcs)) {
+			phylink_err(pl,
+				    "mac_select_pcs unexpectedly failed: %pe\n",
+				    pcs);
+			return;
+		}
+	}
+
 	if (pl->mac_ops->mac_prepare) {
 		err = pl->mac_ops->mac_prepare(pl->config, pl->cur_link_an_mode,
 					       state->interface);
@@ -764,6 +822,12 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 		}
 	}
 
+	/* If we have a new PCS, switch to the new PCS after preparing the MAC
+	 * for the change.
+	 */
+	if (pcs)
+		phylink_set_pcs(pl, pcs);
+
 	phylink_mac_config(pl, state);
 
 	if (pl->pcs_ops) {
@@ -1155,6 +1219,14 @@ struct phylink *phylink_create(struct phylink_config *config,
 	struct phylink *pl;
 	int ret;
 
+	/* Validate the supplied configuration */
+	if (mac_ops->mac_select_pcs &&
+	    phy_interface_empty(config->supported_interfaces)) {
+		dev_err(config->dev,
+			"phylink: error: empty supported_interfaces but mac_select_pcs() method present\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	pl = kzalloc(sizeof(*pl), GFP_KERNEL);
 	if (!pl)
 		return ERR_PTR(-ENOMEM);
@@ -1222,9 +1294,10 @@ EXPORT_SYMBOL_GPL(phylink_create);
  * @pl: a pointer to a &struct phylink returned from phylink_create()
  * @pcs: a pointer to the &struct phylink_pcs
  *
- * Bind the MAC PCS to phylink.  This may be called after phylink_create(),
- * in mac_prepare() or mac_config() methods if it is desired to dynamically
- * change the PCS.
+ * Bind the MAC PCS to phylink.  This may be called after phylink_create().
+ * If it is desired to dynamically change the PCS, then the preferred method
+ * is to use mac_select_pcs(), but it may also be called in mac_prepare()
+ * or mac_config().
  *
  * Please note that there are behavioural changes with the mac_config()
  * callback if a PCS is present (denoting a newer setup) so removing a PCS
@@ -1235,6 +1308,14 @@ void phylink_set_pcs(struct phylink *pl, struct phylink_pcs *pcs)
 {
 	pl->pcs = pcs;
 	pl->pcs_ops = pcs->ops;
+
+	if (!pl->phylink_disable_state &&
+	    pl->cfg_link_an_mode == MLO_AN_INBAND) {
+		if (pl->config->pcs_poll || pcs->poll)
+			mod_timer(&pl->link_poll, jiffies + HZ);
+		else
+			del_timer(&pl->link_poll);
+	}
 }
 EXPORT_SYMBOL_GPL(phylink_set_pcs);
 
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index a2f266cc3442..713a0c928b7c 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -112,6 +112,7 @@ struct phylink_config {
 /**
  * struct phylink_mac_ops - MAC operations structure.
  * @validate: Validate and update the link configuration.
+ * @mac_select_pcs: Select a PCS for the interface mode.
  * @mac_pcs_get_state: Read the current link state from the hardware.
  * @mac_prepare: prepare for a major reconfiguration of the interface.
  * @mac_config: configure the MAC for the selected mode and state.
@@ -126,6 +127,8 @@ struct phylink_mac_ops {
 	void (*validate)(struct phylink_config *config,
 			 unsigned long *supported,
 			 struct phylink_link_state *state);
+	struct phylink_pcs *(*mac_select_pcs)(struct phylink_config *config,
+					      phy_interface_t interface);
 	void (*mac_pcs_get_state)(struct phylink_config *config,
 				  struct phylink_link_state *state);
 	int (*mac_prepare)(struct phylink_config *config, unsigned int mode,
@@ -178,6 +181,21 @@ struct phylink_mac_ops {
  */
 void validate(struct phylink_config *config, unsigned long *supported,
 	      struct phylink_link_state *state);
+/**
+ * mac_select_pcs: Select a PCS for the interface mode.
+ * @config: a pointer to a &struct phylink_config.
+ * @interface: PHY interface mode for PCS
+ *
+ * Return the &struct phylink_pcs for the specified interface mode, or
+ * NULL if none is required, or an error pointer on error.
+ *
+ * This must not modify any state. It is used to query which PCS should
+ * be used. Phylink will use this during validation to ensure that the
+ * configuration is valid, and when setting a configuration to internally
+ * set the PCS that will be used.
+ */
+struct phylink_pcs *mac_select_pcs(struct phylink_config *config,
+				   phy_interface_t interface);
 
 /**
  * mac_pcs_get_state() - Read the current inband link state from the hardware
@@ -398,6 +416,7 @@ struct phylink_pcs {
 
 /**
  * struct phylink_pcs_ops - MAC PCS operations structure.
+ * @pcs_validate: validate the link configuration.
  * @pcs_get_state: read the current MAC PCS link state from the hardware.
  * @pcs_config: configure the MAC PCS for the selected mode and state.
  * @pcs_an_restart: restart 802.3z BaseX autonegotiation.
@@ -405,6 +424,8 @@ struct phylink_pcs {
  *               (where necessary).
  */
 struct phylink_pcs_ops {
+	int (*pcs_validate)(struct phylink_pcs *pcs, unsigned long *supported,
+			    const struct phylink_link_state *state);
 	void (*pcs_get_state)(struct phylink_pcs *pcs,
 			      struct phylink_link_state *state);
 	int (*pcs_config)(struct phylink_pcs *pcs, unsigned int mode,
@@ -418,6 +439,23 @@ struct phylink_pcs_ops {
 
 #if 0 /* For kernel-doc purposes only. */
 /**
+ * pcs_validate() - validate the link configuration.
+ * @pcs: a pointer to a &struct phylink_pcs.
+ * @supported: ethtool bitmask for supported link modes.
+ * @state: a const pointer to a &struct phylink_link_state.
+ *
+ * Validate the interface mode, and advertising's autoneg bit, removing any
+ * media ethtool link modes that would not be supportable from the supported
+ * mask. Phylink will propagate the changes to the advertising mask. See the
+ * &struct phylink_mac_ops validate() method.
+ *
+ * Returns -EINVAL if the interface mode/autoneg mode is not supported.
+ * Returns non-zero positive if the link state can be supported.
+ */
+int pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
+		 const struct phylink_link_state *state);
+
+/**
  * pcs_get_state() - Read the current inband link state from the hardware
  * @pcs: a pointer to a &struct phylink_pcs.
  * @state: a pointer to a &struct phylink_link_state.