net: phy: bcm-phy-lib: Implement BroadR-Reach link modes

Implement single-pair BroadR-Reach modes on bcm5481x PHY by Broadcom.
Create set of functions alternative to IEEE 802.3 to handle
configuration of these modes on compatible Broadcom PHYs.
There is only subset of capabilities supported because of limited
collection of hardware available for the development.
For BroadR-Reach capable PHYs, the LRE (Long Reach Ethernet)
alternative register set is handled. Only bcm54811 PHY is verified,
for bcm54810, there is some support possible but untested. There
is no auto-negotiation of the link parameters (called LDS in the
Broadcom terminology, Long-Distance Signaling) for bcm54811.
It should be possible to enable LDS for bcm54810.

Signed-off-by: Kamil Horák (2N) <kamilh@axis.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20240712150709.3134474-5-kamilh@axis.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Kamil Horák (2N)

drivers/net/phy/bcm-phy-lib.c

@@ -794,6 +794,49 @@ static int _bcm_phy_cable_test_get_status(struct phy_device *phydev,
 	return ret;
 }
 
+static int bcm_setup_lre_forced(struct phy_device *phydev)
+{
+	u16 ctl = 0;
+
+	phydev->pause = 0;
+	phydev->asym_pause = 0;
+
+	if (phydev->speed == SPEED_100)
+		ctl |= LRECR_SPEED100;
+
+	if (phydev->duplex != DUPLEX_FULL)
+		return -EOPNOTSUPP;
+
+	return phy_modify(phydev, MII_BCM54XX_LRECR, LRECR_SPEED100, ctl);
+}
+
+/**
+ * bcm_linkmode_adv_to_lre_adv_t - translate linkmode advertisement to LDS
+ * @advertising: the linkmode advertisement settings
+ * Return: LDS Auto-Negotiation Advertised Ability register value
+ *
+ * A small helper function that translates linkmode advertisement
+ * settings to phy LDS autonegotiation advertisements for the
+ * MII_BCM54XX_LREANAA register of Broadcom PHYs capable of LDS
+ */
+static u32 bcm_linkmode_adv_to_lre_adv_t(unsigned long *advertising)
+{
+	u32 result = 0;
+
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_10baseT1BRR_Full_BIT,
+			      advertising))
+		result |= LREANAA_10_1PAIR;
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_100baseT1_Full_BIT,
+			      advertising))
+		result |= LREANAA_100_1PAIR;
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertising))
+		result |= LRELPA_PAUSE;
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertising))
+		result |= LRELPA_PAUSE_ASYM;
+
+	return result;
+}
+
 int bcm_phy_cable_test_start(struct phy_device *phydev)
 {
 	return _bcm_phy_cable_test_start(phydev, false);
@@ -1066,6 +1109,78 @@ int bcm_phy_led_brightness_set(struct phy_device *phydev,
 }
 EXPORT_SYMBOL_GPL(bcm_phy_led_brightness_set);
 
+int bcm_setup_lre_master_slave(struct phy_device *phydev)
+{
+	u16 ctl = 0;
+
+	switch (phydev->master_slave_set) {
+	case MASTER_SLAVE_CFG_MASTER_PREFERRED:
+	case MASTER_SLAVE_CFG_MASTER_FORCE:
+		ctl = LRECR_MASTER;
+		break;
+	case MASTER_SLAVE_CFG_SLAVE_PREFERRED:
+	case MASTER_SLAVE_CFG_SLAVE_FORCE:
+		break;
+	case MASTER_SLAVE_CFG_UNKNOWN:
+	case MASTER_SLAVE_CFG_UNSUPPORTED:
+		return 0;
+	default:
+		phydev_warn(phydev, "Unsupported Master/Slave mode\n");
+		return -EOPNOTSUPP;
+	}
+
+	return phy_modify_changed(phydev, MII_BCM54XX_LRECR, LRECR_MASTER, ctl);
+}
+EXPORT_SYMBOL_GPL(bcm_setup_lre_master_slave);
+
+int bcm_config_lre_aneg(struct phy_device *phydev, bool changed)
+{
+	int err;
+
+	if (genphy_config_eee_advert(phydev))
+		changed = true;
+
+	err = bcm_setup_lre_master_slave(phydev);
+	if (err < 0)
+		return err;
+	else if (err)
+		changed = true;
+
+	if (phydev->autoneg != AUTONEG_ENABLE)
+		return bcm_setup_lre_forced(phydev);
+
+	err = bcm_config_lre_advert(phydev);
+	if (err < 0)
+		return err;
+	else if (err)
+		changed = true;
+
+	return genphy_check_and_restart_aneg(phydev, changed);
+}
+EXPORT_SYMBOL_GPL(bcm_config_lre_aneg);
+
+/**
+ * bcm_config_lre_advert - sanitize and advertise Long-Distance Signaling
+ *  auto-negotiation parameters
+ * @phydev: target phy_device struct
+ * Return:  0 if the PHY's advertisement hasn't changed, < 0 on error,
+ *          > 0 if it has changed
+ *
+ * Writes MII_BCM54XX_LREANAA with the appropriate values. The values are to be
+ *   sanitized before, to make sure we only advertise what is supported.
+ *  The sanitization is done already in phy_ethtool_ksettings_set()
+ */
+int bcm_config_lre_advert(struct phy_device *phydev)
+{
+	u32 adv = bcm_linkmode_adv_to_lre_adv_t(phydev->advertising);
+
+	/* Setup BroadR-Reach mode advertisement */
+	return phy_modify_changed(phydev, MII_BCM54XX_LREANAA,
+				 LRE_ADVERTISE_ALL | LREANAA_PAUSE |
+				 LREANAA_PAUSE_ASYM, adv);
+}
+EXPORT_SYMBOL_GPL(bcm_config_lre_advert);
+
 MODULE_DESCRIPTION("Broadcom PHY Library");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Broadcom Corporation");

drivers/net/phy/bcm-phy-lib.h

@@ -121,4 +121,8 @@ irqreturn_t bcm_phy_wol_isr(int irq, void *dev_id);
 int bcm_phy_led_brightness_set(struct phy_device *phydev,
 			       u8 index, enum led_brightness value);
 
+int bcm_setup_lre_master_slave(struct phy_device *phydev);
+int bcm_config_lre_aneg(struct phy_device *phydev, bool changed);
+int bcm_config_lre_advert(struct phy_device *phydev);
+
 #endif /* _LINUX_BCM_PHY_LIB_H */