Merge branch 'net-pcs-xpcs-cleanups-for-clause-73-support'

Russell King says:

====================
net: pcs: xpcs: cleanups for clause 73 support

This series cleans up xpcs code, moving much of the clause 73 code
out of the driver into places where others can make use of it.

Specifically, we add a helper to convert a clause 73 advertisement
to ethtool link modes to mdio.h, and a helper to resolve the clause
73 negotiation state to phylink, which includes the pause modes.

In doing this cleanup, several issues were identified with the
original xpcs implementation:

1) it masks the link partner advertisement with its own advertisement
   so userspace can't see what the full link partner advertisement
   was.
2) it was always setting pause modes irrespective of the advertisements
   on either end of the link.
3) it was reading the STAT1 registers multiple times. Reading STAT1
   has the side effect of unlatching the link-down status, so
   multiple reads should be avoided.

This patch series addresses the first two first by addressing the
issues, and then by moving over to the new helpers. The third issue
is solved by restructuring the xpcs code.
====================

Link: https://lore.kernel.org/r/ZGyR/jDyYTYzRklg@shell.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 43 insertions, 11 deletions

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 093b7b6e0263..28417d307cf0 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -977,11 +977,10 @@ static void phylink_apply_manual_flow(struct phylink *pl,
 		state->pause = pl->link_config.pause;
 }
 
-static void phylink_resolve_flow(struct phylink_link_state *state)
+static void phylink_resolve_an_pause(struct phylink_link_state *state)
 {
 	bool tx_pause, rx_pause;
 
-	state->pause = MLO_PAUSE_NONE;
 	if (state->duplex == DUPLEX_FULL) {
 		linkmode_resolve_pause(state->advertising,
 				       state->lp_advertising,
@@ -1193,7 +1192,8 @@ static void phylink_get_fixed_state(struct phylink *pl,
 	else if (pl->link_gpio)
 		state->link = !!gpiod_get_value_cansleep(pl->link_gpio);
 
-	phylink_resolve_flow(state);
+	state->pause = MLO_PAUSE_NONE;
+	phylink_resolve_an_pause(state);
 }
 
 static void phylink_mac_initial_config(struct phylink *pl, bool force_restart)
@@ -3212,10 +3212,48 @@ static const struct sfp_upstream_ops sfp_phylink_ops = {
 
 /* Helpers for MAC drivers */
 
+static struct {
+	int bit;
+	int speed;
+} phylink_c73_priority_resolution[] = {
+	{ ETHTOOL_LINK_MODE_100000baseCR4_Full_BIT, SPEED_100000 },
+	{ ETHTOOL_LINK_MODE_100000baseKR4_Full_BIT, SPEED_100000 },
+	/* 100GBASE-KP4 and 100GBASE-CR10 not supported */
+	{ ETHTOOL_LINK_MODE_40000baseCR4_Full_BIT, SPEED_40000 },
+	{ ETHTOOL_LINK_MODE_40000baseKR4_Full_BIT, SPEED_40000 },
+	{ ETHTOOL_LINK_MODE_10000baseKR_Full_BIT, SPEED_10000 },
+	{ ETHTOOL_LINK_MODE_10000baseKX4_Full_BIT, SPEED_10000 },
+	/* 5GBASE-KR not supported */
+	{ ETHTOOL_LINK_MODE_2500baseX_Full_BIT, SPEED_2500 },
+	{ ETHTOOL_LINK_MODE_1000baseKX_Full_BIT, SPEED_1000 },
+};
+
+void phylink_resolve_c73(struct phylink_link_state *state)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(phylink_c73_priority_resolution); i++) {
+		int bit = phylink_c73_priority_resolution[i].bit;
+		if (linkmode_test_bit(bit, state->advertising) &&
+		    linkmode_test_bit(bit, state->lp_advertising))
+			break;
+	}
+
+	if (i < ARRAY_SIZE(phylink_c73_priority_resolution)) {
+		state->speed = phylink_c73_priority_resolution[i].speed;
+		state->duplex = DUPLEX_FULL;
+	} else {
+		/* negotiation failure */
+		state->link = false;
+	}
+
+	phylink_resolve_an_pause(state);
+}
+EXPORT_SYMBOL_GPL(phylink_resolve_c73);
+
 static void phylink_decode_c37_word(struct phylink_link_state *state,
 				    uint16_t config_reg, int speed)
 {
-	bool tx_pause, rx_pause;
 	int fd_bit;
 
 	if (speed == SPEED_2500)
@@ -3234,13 +3272,7 @@ static void phylink_decode_c37_word(struct phylink_link_state *state,
 		state->link = false;
 	}
 
-	linkmode_resolve_pause(state->advertising, state->lp_advertising,
-			       &tx_pause, &rx_pause);
-
-	if (tx_pause)
-		state->pause |= MLO_PAUSE_TX;
-	if (rx_pause)
-		state->pause |= MLO_PAUSE_RX;
+	phylink_resolve_an_pause(state);
 }
 
 static void phylink_decode_sgmii_word(struct phylink_link_state *state,