From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Thu, 9 Aug 2018 15:38:38 +0200
Subject: phylink: add helper for configuring 2500BaseX modes
Patch-mainline: v4.19-rc1
Git-commit: 624c0f0239f04cce78c86afa95eb2841c84fbab1
References: bsc#1119113 FATE#326472

Add a helper for MAC drivers to use in their validate callback to deal
with 2500BaseX vs 1000BaseX modes, where the hardware supports both
but it is not possible to automatically select between them.

This helper defaults to 1000BaseX, as that is the 802.3 standard, and
will allow users to select 2500BaseX either by forcing the speed if
AN is disabled, or by changing the advertising mask if AN is enabled.
Disabling AN is not recommended as it is only the speed that we're
interested in controlling, not the duplex or pause mode parameters.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/phy/phylink.c |   30 ++++++++++++++++++++++++++++++
 include/linux/phylink.h   |    1 +
 2 files changed, 31 insertions(+)

--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1688,4 +1688,34 @@ static const struct sfp_upstream_ops sfp
 	.disconnect_phy = phylink_sfp_disconnect_phy,
 };
 
+/* Helpers for MAC drivers */
+
+/**
+ * phylink_helper_basex_speed() - 1000BaseX/2500BaseX helper
+ * @state: a pointer to a &struct phylink_link_state
+ *
+ * Inspect the interface mode, advertising mask or forced speed and
+ * decide whether to run at 2.5Gbit or 1Gbit appropriately, switching
+ * the interface mode to suit.  @state->interface is appropriately
+ * updated, and the advertising mask has the "other" baseX_Full flag
+ * cleared.
+ */
+void phylink_helper_basex_speed(struct phylink_link_state *state)
+{
+	if (phy_interface_mode_is_8023z(state->interface)) {
+		bool want_2500 = state->an_enabled ?
+			phylink_test(state->advertising, 2500baseX_Full) :
+			state->speed == SPEED_2500;
+
+		if (want_2500) {
+			phylink_clear(state->advertising, 1000baseX_Full);
+			state->interface = PHY_INTERFACE_MODE_2500BASEX;
+		} else {
+			phylink_clear(state->advertising, 2500baseX_Full);
+			state->interface = PHY_INTERFACE_MODE_1000BASEX;
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_helper_basex_speed);
+
 MODULE_LICENSE("GPL");
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -234,5 +234,6 @@ int phylink_mii_ioctl(struct phylink *,
 #define phylink_test(bm, mode)	__phylink_do_bit(test_bit, bm, mode)
 
 void phylink_set_port_modes(unsigned long *bits);
+void phylink_helper_basex_speed(struct phylink_link_state *state);
 
 #endif