net: phy: add genphy_c45_read_eee_abilities() function

Add generic function for EEE abilities defined by IEEE 802.3
specification. For now following registers are supported:
- IEEE 802.3-2018 45.2.3.10 EEE control and capability 1 (Register 3.20)
- IEEE 802.3cg-2019 45.2.1.186b 10BASE-T1L PMA status register
  (Register 1.2295)

Since I was not able to find any flag signaling support of these
registers, we should detect link mode abilities first and then based on
these abilities doing EEE link modes detection.

Results of EEE ability detection will be stored into new variable
phydev->supported_eee.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 70 insertions, 0 deletions

diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c
index 9f9565a4819d..2d10d22e7684 100644
--- a/drivers/net/phy/phy-c45.c
+++ b/drivers/net/phy/phy-c45.c
@@ -662,6 +662,76 @@ int genphy_c45_read_mdix(struct phy_device *phydev)
 EXPORT_SYMBOL_GPL(genphy_c45_read_mdix);
 
 /**
+ * genphy_c45_read_eee_cap1 - read supported EEE link modes from register 3.20
+ * @phydev: target phy_device struct
+ */
+static int genphy_c45_read_eee_cap1(struct phy_device *phydev)
+{
+	int val;
+
+	/* IEEE 802.3-2018 45.2.3.10 EEE control and capability 1
+	 * (Register 3.20)
+	 */
+	val = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_EEE_ABLE);
+	if (val < 0)
+		return val;
+
+	/* The 802.3 2018 standard says the top 2 bits are reserved and should
+	 * read as 0. Also, it seems unlikely anybody will build a PHY which
+	 * supports 100GBASE-R deep sleep all the way down to 100BASE-TX EEE.
+	 * If MDIO_PCS_EEE_ABLE is 0xffff assume EEE is not supported.
+	 */
+	if (val == 0xffff)
+		return 0;
+
+	mii_eee_cap1_mod_linkmode_t(phydev->supported_eee, val);
+
+	/* Some buggy devices indicate EEE link modes in MDIO_PCS_EEE_ABLE
+	 * which they don't support as indicated by BMSR, ESTATUS etc.
+	 */
+	linkmode_and(phydev->supported_eee, phydev->supported_eee,
+		     phydev->supported);
+
+	return 0;
+}
+
+/**
+ * genphy_c45_read_eee_abilities - read supported EEE link modes
+ * @phydev: target phy_device struct
+ */
+int genphy_c45_read_eee_abilities(struct phy_device *phydev)
+{
+	int val;
+
+	/* There is not indicator whether optional register
+	 * "EEE control and capability 1" (3.20) is supported. Read it only
+	 * on devices with appropriate linkmodes.
+	 */
+	if (linkmode_intersects(phydev->supported, PHY_EEE_CAP1_FEATURES)) {
+		val = genphy_c45_read_eee_cap1(phydev);
+		if (val)
+			return val;
+	}
+
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_10baseT1L_Full_BIT,
+			      phydev->supported)) {
+		/* IEEE 802.3cg-2019 45.2.1.186b 10BASE-T1L PMA status register
+		 * (Register 1.2295)
+		 */
+		val = phy_read_mmd(phydev, MDIO_MMD_PMAPMD, MDIO_PMA_10T1L_STAT);
+		if (val < 0)
+			return val;
+
+		linkmode_mod_bit(ETHTOOL_LINK_MODE_10baseT1L_Full_BIT,
+				 phydev->supported_eee,
+				 val & MDIO_PMA_10T1L_STAT_EEE);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(genphy_c45_read_eee_abilities);
+
+/**
  * genphy_c45_pma_read_abilities - read supported link modes from PMA
  * @phydev: target phy_device struct
  *