[PATCH net-next 05/13] net: phy: Create a phy_port for PHY-driven SFPs

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Some PHY devices may be used as media-converters to drive SFP ports (for
example, to allow using SFP when the SoC can only output RGMII). This is
already supported to some extend by allowing PHY drivers to registers
themselves as being SFP upstream.

However, the logic to drive the SFP can actually be split to a per-port
control logic, allowing support for multi-port PHYs, or PHYs that can
either drive SFPs or Copper.

To that extent, create a phy_port when registering an SFP bus onto a
PHY. This port is considered a "serdes" port, in that it can feed data
to anther entity on the link. The PHY driver needs to specify the
various PHY_INTERFACE_MODE_XXX that this port supports.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 drivers/net/phy/phy_device.c | 21 +++++++++++++++++++++
 drivers/net/phy/phy_port.c   | 10 ++++++++++
 drivers/net/phy/phylink.c    | 32 ++++++++++++++++++++++++++++++++
 include/linux/phylink.h      |  2 ++
 4 files changed, 65 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index df016d344c55..56928c4459c6 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1460,6 +1460,23 @@ static void phy_del_port(struct phy_device *phydev, struct phy_port *port)
 	phydev->n_ports--;
 }
 
+static int phy_setup_sfp_port(struct phy_device *phydev)
+{
+	struct phy_port *port = phy_port_alloc();
+
+	if (!port)
+		return -ENOMEM;
+
+	port->parent_type = PHY_PORT_PHY;
+	port->phy = phydev;
+
+	port->is_serdes = true;
+
+	phy_add_port(phydev, port);
+
+	return 0;
+}
+
 /**
  * phy_sfp_probe - probe for a SFP cage attached to this PHY device
  * @phydev: Pointer to phy_device
@@ -1481,6 +1498,10 @@ int phy_sfp_probe(struct phy_device *phydev,
 		ret = sfp_bus_add_upstream(bus, phydev, ops);
 		sfp_bus_put(bus);
 	}
+
+	if (phydev->sfp_bus)
+		ret = phy_setup_sfp_port(phydev);
+
 	return ret;
 }
 EXPORT_SYMBOL(phy_sfp_probe);
diff --git a/drivers/net/phy/phy_port.c b/drivers/net/phy/phy_port.c
index 3a7bdc44b556..7fba101369cf 100644
--- a/drivers/net/phy/phy_port.c
+++ b/drivers/net/phy/phy_port.c
@@ -7,6 +7,7 @@
 #include <linux/linkmode.h>
 #include <linux/of.h>
 #include <linux/phy_port.h>
+#include <linux/phylink.h>
 
 /**
  * phy_port_alloc: Allocate a new phy_port
@@ -146,6 +147,15 @@ void phy_port_update_supported(struct phy_port *port)
 		ethtool_medium_get_supported(supported, i, port->lanes);
 		linkmode_or(port->supported, port->supported, supported);
 	}
+
+	/* Serdes ports supported may through SFP may not have any medium set,
+	 * as they will output PHY_INTERFACE_MODE_XXX modes. In that case, derive
+	 * the supported list based on these interfaces
+	 */
+	if (port->is_serdes && linkmode_empty(supported))
+		phylink_interfaces_to_linkmodes(port->supported,
+						port->interfaces);
+
 }
 EXPORT_SYMBOL_GPL(phy_port_update_supported);
 
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 214b62fba991..a49edc012636 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -673,6 +673,38 @@ static void phylink_validate_mask_caps(unsigned long *supported,
 	linkmode_and(state->advertising, state->advertising, mask);
 }
 
+/**
+ * phylink_interfaces_to_linkmodes() - List all possible linkmodes based on a
+ *				       set of supported interfaces, assuming no
+ *				       rate matching.
+ * @linkmodes: the supported linkmodes
+ * @interfaces: Set of interfaces (PHY_INTERFACE_MODE_XXX)
+ *
+ * Compute the exhaustive list of modes that can conceivably be achieved from a
+ * set of MII interfaces. This is derived from the possible speeds and duplex
+ * achievable from these interfaces. This list is likely too exhaustive (there
+ * may not exist any device out there that can convert from an interface to a
+ * linkmode) and it needs further filtering based on real HW capabilities.
+ */
+void phylink_interfaces_to_linkmodes(unsigned long *linkmodes,
+				     const unsigned long *interfaces)
+{
+	phy_interface_t interface;
+	unsigned long caps = 0;
+
+	linkmode_zero(linkmodes);
+
+	for_each_set_bit(interface, interfaces, PHY_INTERFACE_MODE_MAX)
+		caps = phylink_get_capabilities(interface,
+						GENMASK(__fls(MAC_400000FD),
+							__fls(MAC_10HD)),
+						RATE_MATCH_NONE);
+
+	phylink_set(linkmodes, Autoneg);
+	phylink_caps_to_linkmodes(linkmodes, caps);
+}
+EXPORT_SYMBOL_GPL(phylink_interfaces_to_linkmodes);
+
 static int phylink_validate_mac_and_pcs(struct phylink *pl,
 					unsigned long *supported,
 					struct phylink_link_state *state)
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 898b00451bbf..ffd8dd32ff3d 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -176,6 +176,8 @@ struct phylink_config {
 };
 
 void phylink_limit_mac_speed(struct phylink_config *config, u32 max_speed);
+void phylink_interfaces_to_linkmodes(unsigned long *linkmodes,
+				     const unsigned long *interfaces);
 
 /**
  * struct phylink_mac_ops - MAC operations structure.
-- 
2.48.1