[PATCH net-next 2/2] net: phy: at803x: Support downstream SFP cage

[Robert Hancock <robert.hancock@calian.com>]

Add support for downstream SFP cages for AR8031 and AR8033. This is
primarily intended for fiber modules or direct-attach cables, however
copper modules which work in 1000Base-X mode may also function. Such
modules are allowed with a warning.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
---
 drivers/net/phy/at803x.c | 53 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 65f546eca5f4..b613e26b6b16 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -19,6 +19,8 @@
 #include <linux/regulator/of_regulator.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/consumer.h>
+#include <linux/phylink.h>
+#include <linux/sfp.h>
 #include <dt-bindings/net/qca-ar803x.h>
 
 #define AT803X_SPECIFIC_FUNCTION_CONTROL	0x10
@@ -552,6 +554,51 @@ static bool at803x_match_phy_id(struct phy_device *phydev, u32 phy_id)
 		== (phy_id & phydev->drv->phy_id_mask);
 }
 
+static int at803x_sfp_insert(void *upstream, const struct sfp_eeprom_id *id)
+{
+	struct phy_device *phydev = upstream;
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(phy_support);
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(sfp_support);
+	phy_interface_t iface;
+
+	linkmode_zero(phy_support);
+	phylink_set(phy_support, 1000baseX_Full);
+	phylink_set(phy_support, 1000baseT_Full);
+	phylink_set(phy_support, Autoneg);
+	phylink_set(phy_support, Pause);
+	phylink_set(phy_support, Asym_Pause);
+
+	linkmode_zero(sfp_support);
+	sfp_parse_support(phydev->sfp_bus, id, sfp_support);
+	/* Some modules support 10G modes as well as others we support.
+	 * Mask out non-supported modes so the correct interface is picked.
+	 */
+	linkmode_and(sfp_support, phy_support, sfp_support);
+
+	iface = sfp_select_interface(phydev->sfp_bus, sfp_support);
+
+	/* Only 1000Base-X is supported by AR8031/8033 as the downstream SerDes
+	 * interface for use with SFP modules.
+	 * However, some copper modules detected as having a preferred SGMII
+	 * interface do default to and function in 1000Base-X mode, so just
+	 * print a warning and allow such modules, as they may have some chance
+	 * of working.
+	 */
+	if (iface == PHY_INTERFACE_MODE_SGMII) {
+		dev_warn(&phydev->mdio.dev, "module may not function if 1000Base-X not supported\n");
+	} else if (iface != PHY_INTERFACE_MODE_1000BASEX) {
+		dev_err(&phydev->mdio.dev, "incompatible SFP module inserted\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static const struct sfp_upstream_ops at803x_sfp_ops = {
+	.attach = phy_sfp_attach,
+	.detach = phy_sfp_detach,
+	.module_insert = at803x_sfp_insert,
+};
+
 static int at803x_parse_dt(struct phy_device *phydev)
 {
 	struct device_node *node = phydev->mdio.dev.of_node;
@@ -716,6 +763,12 @@ static int at803x_probe(struct phy_device *phydev)
 		phy_unlock_mdio_bus(phydev);
 		if (ret)
 			goto err;
+
+		if (priv->is_1000basex) {
+			ret = phy_sfp_probe(phydev, &at803x_sfp_ops);
+			if (ret < 0)
+				goto err;
+		}
 	}
 
 	return 0;
-- 
2.27.0