net: phylink: pcs: add 802.3 clause 22 helpers

Implement helpers for PCS accessed via the MII bus using 802.3 clause
22 cycles, conforming to 802.3 clause 37 and Cisco SGMII specifications
for the advertisement word.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phylink.c

@@ -2068,4 +2068,210 @@ void phylink_helper_basex_speed(struct phylink_link_state *state)
 }
 EXPORT_SYMBOL_GPL(phylink_helper_basex_speed);
 
+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)
+		fd_bit = ETHTOOL_LINK_MODE_2500baseX_Full_BIT;
+	else
+		fd_bit = ETHTOOL_LINK_MODE_1000baseX_Full_BIT;
+
+	mii_lpa_mod_linkmode_x(state->lp_advertising, config_reg, fd_bit);
+
+	if (linkmode_test_bit(fd_bit, state->advertising) &&
+	    linkmode_test_bit(fd_bit, state->lp_advertising)) {
+		state->speed = speed;
+		state->duplex = DUPLEX_FULL;
+	} else {
+		/* negotiation failure */
+		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;
+}
+
+static void phylink_decode_sgmii_word(struct phylink_link_state *state,
+				      uint16_t config_reg)
+{
+	if (!(config_reg & LPA_SGMII_LINK)) {
+		state->link = false;
+		return;
+	}
+
+	switch (config_reg & LPA_SGMII_SPD_MASK) {
+	case LPA_SGMII_10:
+		state->speed = SPEED_10;
+		break;
+	case LPA_SGMII_100:
+		state->speed = SPEED_100;
+		break;
+	case LPA_SGMII_1000:
+		state->speed = SPEED_1000;
+		break;
+	default:
+		state->link = false;
+		return;
+	}
+	if (config_reg & LPA_SGMII_FULL_DUPLEX)
+		state->duplex = DUPLEX_FULL;
+	else
+		state->duplex = DUPLEX_HALF;
+}
+
+/**
+ * phylink_mii_c22_pcs_get_state() - read the MAC PCS state
+ * @pcs: a pointer to a &struct mdio_device.
+ * @state: a pointer to a &struct phylink_link_state.
+ *
+ * Helper for MAC PCS supporting the 802.3 clause 22 register set for
+ * clause 37 negotiation and/or SGMII control.
+ *
+ * Read the MAC PCS state from the MII device configured in @config and
+ * parse the Clause 37 or Cisco SGMII link partner negotiation word into
+ * the phylink @state structure. This is suitable to be directly plugged
+ * into the mac_pcs_get_state() member of the struct phylink_mac_ops
+ * structure.
+ */
+void phylink_mii_c22_pcs_get_state(struct mdio_device *pcs,
+				   struct phylink_link_state *state)
+{
+	struct mii_bus *bus = pcs->bus;
+	int addr = pcs->addr;
+	int bmsr, lpa;
+
+	bmsr = mdiobus_read(bus, addr, MII_BMSR);
+	lpa = mdiobus_read(bus, addr, MII_LPA);
+	if (bmsr < 0 || lpa < 0) {
+		state->link = false;
+		return;
+	}
+
+	state->link = !!(bmsr & BMSR_LSTATUS);
+	state->an_complete = !!(bmsr & BMSR_ANEGCOMPLETE);
+	if (!state->link)
+		return;
+
+	switch (state->interface) {
+	case PHY_INTERFACE_MODE_1000BASEX:
+		phylink_decode_c37_word(state, lpa, SPEED_1000);
+		break;
+
+	case PHY_INTERFACE_MODE_2500BASEX:
+		phylink_decode_c37_word(state, lpa, SPEED_2500);
+		break;
+
+	case PHY_INTERFACE_MODE_SGMII:
+		phylink_decode_sgmii_word(state, lpa);
+		break;
+
+	default:
+		state->link = false;
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_mii_c22_pcs_get_state);
+
+/**
+ * phylink_mii_c22_pcs_set_advertisement() - configure the clause 37 PCS
+ *	advertisement
+ * @pcs: a pointer to a &struct mdio_device.
+ * @state: a pointer to the state being configured.
+ *
+ * Helper for MAC PCS supporting the 802.3 clause 22 register set for
+ * clause 37 negotiation and/or SGMII control.
+ *
+ * Configure the clause 37 PCS advertisement as specified by @state. This
+ * does not trigger a renegotiation; phylink will do that via the
+ * mac_an_restart() method of the struct phylink_mac_ops structure.
+ *
+ * Returns negative error code on failure to configure the advertisement,
+ * zero if no change has been made, or one if the advertisement has changed.
+ */
+int phylink_mii_c22_pcs_set_advertisement(struct mdio_device *pcs,
+					const struct phylink_link_state *state)
+{
+	struct mii_bus *bus = pcs->bus;
+	int addr = pcs->addr;
+	int val, ret;
+	u16 adv;
+
+	switch (state->interface) {
+	case PHY_INTERFACE_MODE_1000BASEX:
+	case PHY_INTERFACE_MODE_2500BASEX:
+		adv = ADVERTISE_1000XFULL;
+		if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
+				      state->advertising))
+			adv |= ADVERTISE_1000XPAUSE;
+		if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT,
+				      state->advertising))
+			adv |= ADVERTISE_1000XPSE_ASYM;
+
+		val = mdiobus_read(bus, addr, MII_ADVERTISE);
+		if (val < 0)
+			return val;
+
+		if (val == adv)
+			return 0;
+
+		ret = mdiobus_write(bus, addr, MII_ADVERTISE, adv);
+		if (ret < 0)
+			return ret;
+
+		return 1;
+
+	case PHY_INTERFACE_MODE_SGMII:
+		val = mdiobus_read(bus, addr, MII_ADVERTISE);
+		if (val < 0)
+			return val;
+
+		if (val == 0x0001)
+			return 0;
+
+		ret = mdiobus_write(bus, addr, MII_ADVERTISE, 0x0001);
+		if (ret < 0)
+			return ret;
+
+		return 1;
+
+	default:
+		/* Nothing to do for other modes */
+		return 0;
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_mii_c22_pcs_set_advertisement);
+
+/**
+ * phylink_mii_c22_pcs_an_restart() - restart 802.3z autonegotiation
+ * @pcs: a pointer to a &struct mdio_device.
+ *
+ * Helper for MAC PCS supporting the 802.3 clause 22 register set for
+ * clause 37 negotiation.
+ *
+ * Restart the clause 37 negotiation with the link partner. This is
+ * suitable to be directly plugged into the mac_pcs_get_state() member
+ * of the struct phylink_mac_ops structure.
+ */
+void phylink_mii_c22_pcs_an_restart(struct mdio_device *pcs)
+{
+	struct mii_bus *bus = pcs->bus;
+	int val, addr = pcs->addr;
+
+	val = mdiobus_read(bus, addr, MII_BMCR);
+	if (val >= 0) {
+		val |= BMCR_ANRESTART;
+
+		mdiobus_write(bus, addr, MII_BMCR, val);
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_mii_c22_pcs_an_restart);
+
 MODULE_LICENSE("GPL v2");

include/linux/phylink.h

@@ -317,4 +317,10 @@ int phylink_mii_ioctl(struct phylink *, struct ifreq *, int);
 void phylink_set_port_modes(unsigned long *bits);
 void phylink_helper_basex_speed(struct phylink_link_state *state);
 
+void phylink_mii_c22_pcs_get_state(struct mdio_device *pcs,
+				   struct phylink_link_state *state);
+int phylink_mii_c22_pcs_set_advertisement(struct mdio_device *pcs,
+					const struct phylink_link_state *state);
+void phylink_mii_c22_pcs_an_restart(struct mdio_device *pcs);
+
 #endif

include/uapi/linux/mii.h

@@ -134,11 +134,16 @@
 /* MAC and PHY tx_config_Reg[15:0] for SGMII in-band auto-negotiation.*/
 #define ADVERTISE_SGMII		0x0001	/* MAC can do SGMII            */
 #define LPA_SGMII		0x0001	/* PHY can do SGMII            */
+#define LPA_SGMII_SPD_MASK	0x0c00	/* SGMII speed mask            */
+#define LPA_SGMII_FULL_DUPLEX	0x1000	/* SGMII full duplex           */
 #define LPA_SGMII_DPX_SPD_MASK	0x1C00	/* SGMII duplex and speed bits */
+#define LPA_SGMII_10		0x0000	/* 10Mbps                      */
 #define LPA_SGMII_10HALF	0x0000	/* Can do 10mbps half-duplex   */
 #define LPA_SGMII_10FULL	0x1000	/* Can do 10mbps full-duplex   */
+#define LPA_SGMII_100		0x0400	/* 100Mbps                     */
 #define LPA_SGMII_100HALF	0x0400	/* Can do 100mbps half-duplex  */
 #define LPA_SGMII_100FULL	0x1400	/* Can do 100mbps full-duplex  */
+#define LPA_SGMII_1000		0x0800	/* 1000Mbps                    */
 #define LPA_SGMII_1000HALF	0x0800	/* Can do 1000mbps half-duplex */
 #define LPA_SGMII_1000FULL	0x1800	/* Can do 1000mbps full-duplex */
 #define LPA_SGMII_LINK		0x8000	/* PHY link with copper-side partner */