Subject: Re: [PATCH net-next 4/5] net: phy: add Lynx PCS MDIO module

From: Russell King - ARM Linux admin <[email-masked]>
Date: Thu, 18 Jun 2020 23:01:01 +0100

On Thu, Jun 18, 2020 at 05:34:49PM +0000, Ioana Ciornei wrote:
> I am not sure how this would work with Felix and DSA drivers in general
> since the DSA core is hiding the phylink_pcs_ops from the actual switch
> driver.

Here's an idea to work around DSA (untested):

diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 1f8e0023f4f4..f578a5bb8ad0 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -67,6 +67,7 @@ enum phylink_op_type {
 struct phylink_config {
 	struct device *dev;
 	enum phylink_op_type type;
+	void *pcs_private;
 	bool pcs_poll;
 	bool poll_fixed_state;
 	void (*get_fixed_state)(struct phylink_config *config,
diff --git a/include/net/dsa.h b/include/net/dsa.h
index a50d5007fd39..0fbb3a542b6e 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -742,6 +742,9 @@ int dsa_port_get_phy_strings(struct dsa_port *dp, uint8_t *data);
 int dsa_port_get_ethtool_phy_stats(struct dsa_port *dp, uint64_t *data);
 int dsa_port_get_phy_sset_count(struct dsa_port *dp);
 void dsa_port_phylink_mac_change(struct dsa_switch *ds, int port, bool up);
+void dsa_slave_attach_phylink_pcs(struct dsa_switch *ds, int port,
+				  const struct phylink_pcs_ops *ops,
+				  void *priv);
 
 struct dsa_tag_driver {
 	const struct dsa_device_ops *ops;
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 2ae17f95cb63..c80f62d88b63 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1619,6 +1619,17 @@ static int dsa_slave_phy_connect(struct net_device *slave_dev, int addr)
 	return phylink_connect_phy(dp->pl, slave_dev->phydev);
 }
 
+void dsa_slave_attach_phylink_pcs(struct dsa_switch *ds, int port,
+				  const struct phylink_pcs_ops *ops,
+				  void *priv)
+{
+	const struct dsa_port *dp = dsa_to_port(ds, port);
+
+	dp->pl_config.pcs_private = priv;
+	phylink_add_pcs(dp->pl, ops);
+}
+EXPORT_SYMBOL_GPL(dsa_slave_attach_phylink_pcs);
+
 static int dsa_slave_phy_setup(struct net_device *slave_dev)
 {
 	struct dsa_port *dp = dsa_slave_to_port(slave_dev);

dsa_slave_attach_phylink_pcs() can be passed anything as it's priv
argument - that could be "dp", or it could be a lynx PCS private
data structure, but that's up to the driver code to decide.

At least this gives a way for us to have some standardised PCS
code that can be bolted into either DSA or a MAC driver by the
higher levels without the PCS code having to know which it's
connected to, and without having to have veneers to bridge into
the PCS code.

-- 
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