phylink: add flow control support

Add flow control support, including ethtool support, to phylink.  We
add support to allow ethtool to get and set the current flow control
settings, and the 802.3 specified resolution for the local and remote
link partner abilities.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 134 insertions, 2 deletions

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 5f416314a76c..417e4608b4a2 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -132,6 +132,9 @@ static int phylink_parse_fixedlink(struct phylink *pl, struct device_node *np)
 
 		if (of_property_read_bool(fixed_node, "full-duplex"))
 			pl->link_config.duplex = DUPLEX_FULL;
+
+		/* We treat the "pause" and "asym-pause" terminology as
+		 * defining the link partner's ability. */
 		if (of_property_read_bool(fixed_node, "pause"))
 			pl->link_config.pause |= MLO_PAUSE_SYM;
 		if (of_property_read_bool(fixed_node, "asym-pause"))
@@ -277,6 +280,56 @@ static void phylink_get_fixed_state(struct phylink *pl, struct phylink_link_stat
 		state->link = !!gpiod_get_value(pl->link_gpio);
 }
 
+/* Flow control is resolved according to our and the link partners
+ * advertisments using the following drawn from the 802.3 specs:
+ *  Local device  Link partner
+ *  Pause AsymDir Pause AsymDir Result
+ *    1     X       1     X     TX+RX
+ *    0     1       1     1     RX
+ *    1     1       0     1     TX
+ */
+static void phylink_resolve_flow(struct phylink *pl,
+	struct phylink_link_state *state)
+{
+	int new_pause = 0;
+
+	if (pl->link_config.pause & MLO_PAUSE_AN) {
+		int pause = 0;
+
+		if (phylink_test(pl->link_config.advertising, Pause))
+			pause |= MLO_PAUSE_SYM;
+		if (phylink_test(pl->link_config.advertising, Asym_Pause))
+			pause |= MLO_PAUSE_ASYM;
+
+		pause &= state->pause;
+
+		if (pause & MLO_PAUSE_SYM)
+			new_pause = MLO_PAUSE_TX | MLO_PAUSE_RX;
+		else if (pause & MLO_PAUSE_ASYM)
+			new_pause = state->pause & MLO_PAUSE_SYM ?
+				 MLO_PAUSE_RX : MLO_PAUSE_TX;
+	} else {
+		new_pause = pl->link_config.pause & MLO_PAUSE_TXRX_MASK;
+	}
+
+	state->pause &= ~MLO_PAUSE_TXRX_MASK;
+	state->pause |= new_pause;
+}
+
+static const char *phylink_pause_to_str(int pause)
+{
+	switch (pause & MLO_PAUSE_TXRX_MASK) {
+	case MLO_PAUSE_TX | MLO_PAUSE_RX:
+		return "rx/tx";
+	case MLO_PAUSE_TX:
+		return "tx";
+	case MLO_PAUSE_RX:
+		return "rx";
+	default:
+		return "off";
+	}
+}
+
 static void phylink_resolve(struct work_struct *w)
 {
 	struct phylink *pl = container_of(w, struct phylink, resolve);
@@ -290,6 +343,7 @@ static void phylink_resolve(struct work_struct *w)
 		switch (pl->link_an_mode) {
 		case MLO_AN_PHY:
 			link_state = pl->phy_state;
+			phylink_resolve_flow(pl, &link_state);
 			break;
 
 		case MLO_AN_FIXED:
@@ -298,9 +352,12 @@ static void phylink_resolve(struct work_struct *w)
 
 		case MLO_AN_SGMII:
 			phylink_get_mac_state(pl, &link_state);
-			if (pl->phydev)
+			if (pl->phydev) {
 				link_state.link = link_state.link &&
 						  pl->phy_state.link;
+				link_state.pause |= pl->phy_state.pause;
+				phylink_resolve_flow(pl, &link_state);
+			}
 			break;
 
 		case MLO_AN_8023Z:
@@ -330,7 +387,7 @@ static void phylink_resolve(struct work_struct *w)
 				    "Link is Up - %s/%s - flow control %s\n",
 				    phy_speed_to_str(link_state.speed),
 				    phy_duplex_to_str(link_state.duplex),
-				    link_state.pause ? "rx/tx" : "off");
+				    phylink_pause_to_str(link_state.pause));
 		}
 	}
 	mutex_unlock(&pl->state_mutex);
@@ -358,6 +415,7 @@ struct phylink *phylink_create(struct net_device *ndev, struct device_node *np,
 	pl->netdev = ndev;
 	pl->link_interface = iface;
 	pl->link_port = PORT_MII;
+	pl->link_config.pause = MLO_PAUSE_AN;
 	pl->link_config.speed = SPEED_UNKNOWN;
 	pl->link_config.duplex = DUPLEX_UNKNOWN;
 	pl->ops = ops;
@@ -580,6 +638,7 @@ void phylink_start(struct phylink *pl)
 	 * a fixed-link to start with the correct parameters, and also
 	 * ensures that we set the appropriate advertisment for Serdes links.
 	 */
+	phylink_resolve_flow(pl, &pl->link_config);
 	phylink_mac_config(pl, &pl->link_config);
 
 	clear_bit(PHYLINK_DISABLE_STOPPED, &pl->phylink_disable_state);
@@ -797,6 +856,79 @@ int phylink_ethtool_nway_reset(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_nway_reset);
 
+void phylink_ethtool_get_pauseparam(struct phylink *pl,
+				    struct ethtool_pauseparam *pause)
+{
+	mutex_lock(&pl->config_mutex);
+
+	pause->autoneg = !!(pl->link_config.pause & MLO_PAUSE_AN);
+	pause->rx_pause = !!(pl->link_config.pause & MLO_PAUSE_RX);
+	pause->tx_pause = !!(pl->link_config.pause & MLO_PAUSE_TX);
+
+	mutex_unlock(&pl->config_mutex);
+}
+EXPORT_SYMBOL_GPL(phylink_ethtool_get_pauseparam);
+
+static int __phylink_ethtool_set_pauseparam(struct phylink *pl,
+					    struct ethtool_pauseparam *pause)
+{
+	struct phylink_link_state *config = &pl->link_config;
+
+	if (!phylink_test(pl->supported, Pause) &&
+	    !phylink_test(pl->supported, Asym_Pause))
+		return -EOPNOTSUPP;
+
+	if (!phylink_test(pl->supported, Asym_Pause) &&
+	    !pause->autoneg && pause->rx_pause != pause->tx_pause)
+		return -EINVAL;
+
+	config->pause &= ~(MLO_PAUSE_AN | MLO_PAUSE_TXRX_MASK);
+
+	if (pause->autoneg)
+		config->pause |= MLO_PAUSE_AN;
+	if (pause->rx_pause)
+		config->pause |= MLO_PAUSE_RX;
+	if (pause->tx_pause)
+		config->pause |= MLO_PAUSE_TX;
+
+	if (!test_bit(PHYLINK_DISABLE_STOPPED, &pl->phylink_disable_state)) {
+		switch (pl->link_an_mode) {
+		case MLO_AN_PHY:
+			/* Silently mark the carrier down, and then trigger a resolve */
+			netif_carrier_off(pl->netdev);
+			phylink_run_resolve(pl);
+			break;
+
+		case MLO_AN_FIXED:
+			/* Should we allow fixed links to change against the config? */
+			phylink_resolve_flow(pl, config);
+			phylink_mac_config(pl, config);
+			break;
+
+		case MLO_AN_SGMII:
+		case MLO_AN_8023Z:
+			phylink_mac_config(pl, config);
+			phylink_mac_an_restart(pl);
+			break;
+		}
+	}
+
+	return 0;
+}
+
+int phylink_ethtool_set_pauseparam(struct phylink *pl,
+				   struct ethtool_pauseparam *pause)
+{
+	int ret;
+
+	mutex_lock(&pl->config_mutex);
+	ret = __phylink_ethtool_set_pauseparam(pl, pause);
+	mutex_unlock(&pl->config_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phylink_ethtool_set_pauseparam);
+
 /* This emulates MII registers for a fixed-mode phy operating as per the
  * passed in state. "aneg" defines if we report negotiation is possible.
  *