net: dsa: add support for mac_prepare() and mac_finish() calls

Add DSA support for the phylink mac_prepare() and mac_finish() calls.
These were introduced as part of the PCS support to allow MACs to
perform preparatory steps prior to configuration, and finalisation
steps after the MAC and PCS has been configured.

Introducing phylink_pcs support to the mv88e6xxx DSA driver needs some
code moved out of its mac_config() stage into the mac_prepare() and
mac_finish() stages, and this commit facilitates such code in DSA
drivers.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -867,9 +867,15 @@ struct dsa_switch_ops {
 						      phy_interface_t iface);
 	int	(*phylink_mac_link_state)(struct dsa_switch *ds, int port,
 					  struct phylink_link_state *state);
+	int	(*phylink_mac_prepare)(struct dsa_switch *ds, int port,
+				       unsigned int mode,
+				       phy_interface_t interface);
 	void	(*phylink_mac_config)(struct dsa_switch *ds, int port,
 				      unsigned int mode,
 				      const struct phylink_link_state *state);
+	int	(*phylink_mac_finish)(struct dsa_switch *ds, int port,
+				      unsigned int mode,
+				      phy_interface_t interface);
 	void	(*phylink_mac_an_restart)(struct dsa_switch *ds, int port);
 	void	(*phylink_mac_link_down)(struct dsa_switch *ds, int port,
 					 unsigned int mode,

net/dsa/port.c

@@ -1603,6 +1603,21 @@ dsa_port_phylink_mac_select_pcs(struct phylink_config *config,
 	return pcs;
 }
 
+static int dsa_port_phylink_mac_prepare(struct phylink_config *config,
+					unsigned int mode,
+					phy_interface_t interface)
+{
+	struct dsa_port *dp = container_of(config, struct dsa_port, pl_config);
+	struct dsa_switch *ds = dp->ds;
+	int err = 0;
+
+	if (ds->ops->phylink_mac_prepare)
+		err = ds->ops->phylink_mac_prepare(ds, dp->index, mode,
+						   interface);
+
+	return err;
+}
+
 static void dsa_port_phylink_mac_config(struct phylink_config *config,
 					unsigned int mode,
 					const struct phylink_link_state *state)
@@ -1616,6 +1631,21 @@ static void dsa_port_phylink_mac_config(struct phylink_config *config,
 	ds->ops->phylink_mac_config(ds, dp->index, mode, state);
 }
 
+static int dsa_port_phylink_mac_finish(struct phylink_config *config,
+				       unsigned int mode,
+				       phy_interface_t interface)
+{
+	struct dsa_port *dp = container_of(config, struct dsa_port, pl_config);
+	struct dsa_switch *ds = dp->ds;
+	int err = 0;
+
+	if (ds->ops->phylink_mac_finish)
+		err = ds->ops->phylink_mac_finish(ds, dp->index, mode,
+						  interface);
+
+	return err;
+}
+
 static void dsa_port_phylink_mac_an_restart(struct phylink_config *config)
 {
 	struct dsa_port *dp = container_of(config, struct dsa_port, pl_config);
@@ -1671,7 +1701,9 @@ static const struct phylink_mac_ops dsa_port_phylink_mac_ops = {
 	.validate = dsa_port_phylink_validate,
 	.mac_select_pcs = dsa_port_phylink_mac_select_pcs,
 	.mac_pcs_get_state = dsa_port_phylink_mac_pcs_get_state,
+	.mac_prepare = dsa_port_phylink_mac_prepare,
 	.mac_config = dsa_port_phylink_mac_config,
+	.mac_finish = dsa_port_phylink_mac_finish,
 	.mac_an_restart = dsa_port_phylink_mac_an_restart,
 	.mac_link_down = dsa_port_phylink_mac_link_down,
 	.mac_link_up = dsa_port_phylink_mac_link_up,