net: phylink: add pcs_inband_caps() method

Add a pcs_inband_caps() method to query the PCS for its inband link
capabilities, and use this to determine whether link modes used with
optical SFPs can be supported.

When a PCS does not provide a method, we allow inband negotiation to
be either on or off, making this a no-op until the pcs_inband_caps()
method is implemented by a PCS driver.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1tIUs4-006IUU-7K@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index fda53dd58285e263424c7857e301c1b8258e9092..42f3c7ccbf382f7987756a24f672b4bf469d7d61 100644 (file)
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -990,6 +990,15 @@ static void phylink_resolve_an_pause(struct phylink_link_state *state)
        }
 }
 
+static unsigned int phylink_pcs_inband_caps(struct phylink_pcs *pcs,
+                                   phy_interface_t interface)
+{
+       if (pcs && pcs->ops->pcs_inband_caps)
+               return pcs->ops->pcs_inband_caps(pcs, interface);
+
+       return 0;
+}
+
 static void phylink_pcs_pre_config(struct phylink_pcs *pcs,
                                   phy_interface_t interface)
 {
@@ -1043,6 +1052,24 @@ static void phylink_pcs_link_up(struct phylink_pcs *pcs, unsigned int neg_mode,
                pcs->ops->pcs_link_up(pcs, neg_mode, interface, speed, duplex);
 }
 
+/* Query inband for a specific interface mode, asking the MAC for the
+ * PCS which will be used to handle the interface mode.
+ */
+static unsigned int phylink_inband_caps(struct phylink *pl,
+                                        phy_interface_t interface)
+{
+       struct phylink_pcs *pcs;
+
+       if (!pl->mac_ops->mac_select_pcs)
+               return 0;
+
+       pcs = pl->mac_ops->mac_select_pcs(pl->config, interface);
+       if (!pcs)
+               return 0;
+
+       return phylink_pcs_inband_caps(pcs, interface);
+}
+
 static void phylink_pcs_poll_stop(struct phylink *pl)
 {
        if (pl->cfg_link_an_mode == MLO_AN_INBAND)
@@ -2532,6 +2559,26 @@ int phylink_ethtool_ksettings_get(struct phylink *pl,
 }
 EXPORT_SYMBOL_GPL(phylink_ethtool_ksettings_get);
 
+static bool phylink_validate_pcs_inband_autoneg(struct phylink *pl,
+                                               phy_interface_t interface,
+                                               unsigned long *adv)
+{
+       unsigned int inband = phylink_inband_caps(pl, interface);
+       unsigned int mask;
+
+       /* If the PCS doesn't implement inband support, be permissive. */
+       if (!inband)
+               return true;
+
+       if (linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, adv))
+               mask = LINK_INBAND_ENABLE;
+       else
+               mask = LINK_INBAND_DISABLE;
+
+       /* Check whether the PCS implements the required mode */
+       return !!(inband & mask);
+}
+
 /**
  * phylink_ethtool_ksettings_set() - set the link settings
  * @pl: a pointer to a &struct phylink returned from phylink_create()
@@ -2662,6 +2709,13 @@ int phylink_ethtool_ksettings_set(struct phylink *pl,
            phylink_is_empty_linkmode(config.advertising))
                return -EINVAL;
 
+       /* Validate the autonegotiation state. We don't have a PHY in this
+        * situation, so the PCS is the media-facing entity.
+        */
+       if (!phylink_validate_pcs_inband_autoneg(pl, config.interface,
+                                                config.advertising))
+               return -EINVAL;
+
        mutex_lock(&pl->state_mutex);
        pl->link_config.speed = config.speed;
        pl->link_config.duplex = config.duplex;
@@ -3341,6 +3395,12 @@ static int phylink_sfp_config_optical(struct phylink *pl)
        phylink_dbg(pl, "optical SFP: chosen %s interface\n",
                    phy_modes(interface));
 
+       if (!phylink_validate_pcs_inband_autoneg(pl, interface,
+                                                config.advertising)) {
+               phylink_err(pl, "autoneg setting not compatible with PCS");
+               return -EINVAL;
+       }
+
        config.interface = interface;
 
        /* Ignore errors if we're expecting a PHY to attach later */

diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 5c01048860c4cb070b50e7e025af70ab3fc2ee9a..5462cc6a37dc21c47f0e4e1147cdb4cc829f5c00 100644 (file)
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -419,6 +419,7 @@ struct phylink_pcs {
 /**
  * struct phylink_pcs_ops - MAC PCS operations structure.
  * @pcs_validate: validate the link configuration.
+ * @pcs_inband_caps: query inband support for interface mode.
  * @pcs_enable: enable the PCS.
  * @pcs_disable: disable the PCS.
  * @pcs_pre_config: pre-mac_config method (for errata)
@@ -434,6 +435,8 @@ struct phylink_pcs {
 struct phylink_pcs_ops {
        int (*pcs_validate)(struct phylink_pcs *pcs, unsigned long *supported,
                            const struct phylink_link_state *state);
+       unsigned int (*pcs_inband_caps)(struct phylink_pcs *pcs,
+                                       phy_interface_t interface);
        int (*pcs_enable)(struct phylink_pcs *pcs);
        void (*pcs_disable)(struct phylink_pcs *pcs);
        void (*pcs_pre_config)(struct phylink_pcs *pcs,
@@ -470,6 +473,20 @@ struct phylink_pcs_ops {
 int pcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
                 const struct phylink_link_state *state);
 
+/**
+ * pcs_inband_caps - query PCS in-band capabilities for interface mode.
+ * @pcs: a pointer to a &struct phylink_pcs.
+ * @interface: interface mode to be queried
+ *
+ * Returns zero if it is unknown what in-band signalling is supported by the
+ * PHY (e.g. because the PHY driver doesn't implement the method.) Otherwise,
+ * returns a bit mask of the LINK_INBAND_* values from
+ * &enum link_inband_signalling to describe which inband modes are supported
+ * for this interface mode.
+ */
+unsigned int pcs_inband_caps(struct phylink_pcs *pcs,
+                            phy_interface_t interface);
+
 /**
  * pcs_enable() - enable the PCS.
  * @pcs: a pointer to a &struct phylink_pcs.