net: phylink: Adjust advertisement based on rate matching

This adds support for adjusting the advertisement for pause-based rate
matching. This may result in a lossy link, since the final link settings
are not adjusted. Asymmetric pause support is necessary. It would be
possible for a MAC supporting only symmetric pause to use pause-based rate
adaptation, but only if pause reception was enabled as well.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 4576395..d0af026 100644 (file)
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -373,18 +373,70 @@ void phylink_caps_to_linkmodes(unsigned long *linkmodes, unsigned long caps)
 }
 EXPORT_SYMBOL_GPL(phylink_caps_to_linkmodes);
 
+static struct {
+       unsigned long mask;
+       int speed;
+       unsigned int duplex;
+} phylink_caps_params[] = {
+       { MAC_400000FD, SPEED_400000, DUPLEX_FULL },
+       { MAC_200000FD, SPEED_200000, DUPLEX_FULL },
+       { MAC_100000FD, SPEED_100000, DUPLEX_FULL },
+       { MAC_56000FD,  SPEED_56000,  DUPLEX_FULL },
+       { MAC_50000FD,  SPEED_50000,  DUPLEX_FULL },
+       { MAC_40000FD,  SPEED_40000,  DUPLEX_FULL },
+       { MAC_25000FD,  SPEED_25000,  DUPLEX_FULL },
+       { MAC_20000FD,  SPEED_20000,  DUPLEX_FULL },
+       { MAC_10000FD,  SPEED_10000,  DUPLEX_FULL },
+       { MAC_5000FD,   SPEED_5000,   DUPLEX_FULL },
+       { MAC_2500FD,   SPEED_2500,   DUPLEX_FULL },
+       { MAC_1000FD,   SPEED_1000,   DUPLEX_FULL },
+       { MAC_1000HD,   SPEED_1000,   DUPLEX_HALF },
+       { MAC_100FD,    SPEED_100,    DUPLEX_FULL },
+       { MAC_100HD,    SPEED_100,    DUPLEX_HALF },
+       { MAC_10FD,     SPEED_10,     DUPLEX_FULL },
+       { MAC_10HD,     SPEED_10,     DUPLEX_HALF },
+};
+
+/**
+ * phylink_cap_from_speed_duplex - Get mac capability from speed/duplex
+ * @speed: the speed to search for
+ * @duplex: the duplex to search for
+ *
+ * Find the mac capability for a given speed and duplex.
+ *
+ * Return: A mask with the mac capability patching @speed and @duplex, or 0 if
+ *         there were no matches.
+ */
+static unsigned long phylink_cap_from_speed_duplex(int speed,
+                                                  unsigned int duplex)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(phylink_caps_params); i++) {
+               if (speed == phylink_caps_params[i].speed &&
+                   duplex == phylink_caps_params[i].duplex)
+                       return phylink_caps_params[i].mask;
+       }
+
+       return 0;
+}
+
 /**
  * phylink_get_capabilities() - get capabilities for a given MAC
  * @interface: phy interface mode defined by &typedef phy_interface_t
  * @mac_capabilities: bitmask of MAC capabilities
+ * @rate_matching: type of rate matching being performed
  *
  * Get the MAC capabilities that are supported by the @interface mode and
  * @mac_capabilities.
  */
 unsigned long phylink_get_capabilities(phy_interface_t interface,
-                                      unsigned long mac_capabilities)
+                                      unsigned long mac_capabilities,
+                                      int rate_matching)
 {
+       int max_speed = phylink_interface_max_speed(interface);
        unsigned long caps = MAC_SYM_PAUSE | MAC_ASYM_PAUSE;
+       unsigned long matched_caps = 0;
 
        switch (interface) {
        case PHY_INTERFACE_MODE_USXGMII:
@@ -458,7 +510,53 @@ unsigned long phylink_get_capabilities(phy_interface_t interface,
                break;
        }
 
-       return caps & mac_capabilities;
+       switch (rate_matching) {
+       case RATE_MATCH_OPEN_LOOP:
+               /* TODO */
+               fallthrough;
+       case RATE_MATCH_NONE:
+               matched_caps = 0;
+               break;
+       case RATE_MATCH_PAUSE: {
+               /* The MAC must support asymmetric pause towards the local
+                * device for this. We could allow just symmetric pause, but
+                * then we might have to renegotiate if the link partner
+                * doesn't support pause. This is because there's no way to
+                * accept pause frames without transmitting them if we only
+                * support symmetric pause.
+                */
+               if (!(mac_capabilities & MAC_SYM_PAUSE) ||
+                   !(mac_capabilities & MAC_ASYM_PAUSE))
+                       break;
+
+               /* We can't adapt if the MAC doesn't support the interface's
+                * max speed at full duplex.
+                */
+               if (mac_capabilities &
+                   phylink_cap_from_speed_duplex(max_speed, DUPLEX_FULL)) {
+                       /* Although a duplex-matching phy might exist, we
+                        * conservatively remove these modes because the MAC
+                        * will not be aware of the half-duplex nature of the
+                        * link.
+                        */
+                       matched_caps = GENMASK(__fls(caps), __fls(MAC_10HD));
+                       matched_caps &= ~(MAC_1000HD | MAC_100HD | MAC_10HD);
+               }
+               break;
+       }
+       case RATE_MATCH_CRS:
+               /* The MAC must support half duplex at the interface's max
+                * speed.
+                */
+               if (mac_capabilities &
+                   phylink_cap_from_speed_duplex(max_speed, DUPLEX_HALF)) {
+                       matched_caps = GENMASK(__fls(caps), __fls(MAC_10HD));
+                       matched_caps &= mac_capabilities;
+               }
+               break;
+       }
+
+       return (caps & mac_capabilities) | matched_caps;
 }
 EXPORT_SYMBOL_GPL(phylink_get_capabilities);
 
@@ -482,7 +580,8 @@ void phylink_generic_validate(struct phylink_config *config,
        phylink_set_port_modes(mask);
        phylink_set(mask, Autoneg);
        caps = phylink_get_capabilities(state->interface,
-                                       config->mac_capabilities);
+                                       config->mac_capabilities,
+                                       state->rate_matching);
        phylink_caps_to_linkmodes(mask, caps);
 
        linkmode_and(supported, supported, mask);
@@ -1512,6 +1611,7 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
                config.interface = PHY_INTERFACE_MODE_NA;
        else
                config.interface = interface;
+       config.rate_matching = phy_get_rate_matching(phy, config.interface);
 
        ret = phylink_validate(pl, supported, &config);
        if (ret) {

diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 5c99c21..664dd40 100644 (file)
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -554,7 +554,8 @@ void pcs_link_up(struct phylink_pcs *pcs, unsigned int mode,
 
 void phylink_caps_to_linkmodes(unsigned long *linkmodes, unsigned long caps);
 unsigned long phylink_get_capabilities(phy_interface_t interface,
-                                      unsigned long mac_capabilities);
+                                      unsigned long mac_capabilities,
+                                      int rate_matching);
 void phylink_generic_validate(struct phylink_config *config,
                              unsigned long *supported,
                              struct phylink_link_state *state);