net: phy: at803x: add support for configuring SmartEEE

SmartEEE for the atheros phy was deemed buggy by Freescale and commits
were added to disable it for their boards.

In initial testing, SolidRun found that the default settings were
causing disconnects but by increasing the Tw buffer time we could allow
enough time for all parts of the link to come out of a low power state
and function properly without causing a disconnect. This allows us to
have functional power savings of between 300 and 400mW, rather than
disabling the feature altogether.

This commit adds support for disabling SmartEEE and configuring the Tw
parameters for 1G and 100M speeds.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/at803x.c

@@ -132,6 +132,11 @@
 #define AT803X_MIN_DOWNSHIFT 2
 #define AT803X_MAX_DOWNSHIFT 9
 
+#define AT803X_MMD3_SMARTEEE_CTL1		0x805b
+#define AT803X_MMD3_SMARTEEE_CTL2		0x805c
+#define AT803X_MMD3_SMARTEEE_CTL3		0x805d
+#define AT803X_MMD3_SMARTEEE_CTL3_LPI_EN	BIT(8)
+
 #define ATH9331_PHY_ID 0x004dd041
 #define ATH8030_PHY_ID 0x004dd076
 #define ATH8031_PHY_ID 0x004dd074
@@ -146,8 +151,11 @@ MODULE_LICENSE("GPL");
 struct at803x_priv {
 	int flags;
 #define AT803X_KEEP_PLL_ENABLED	BIT(0)	/* don't turn off internal PLL */
+#define AT803X_DISABLE_SMARTEEE	BIT(1)
 	u16 clk_25m_reg;
 	u16 clk_25m_mask;
+	u8 smarteee_lpi_tw_1g;
+	u8 smarteee_lpi_tw_100m;
 	struct regulator_dev *vddio_rdev;
 	struct regulator_dev *vddh_rdev;
 	struct regulator *vddio;
@@ -411,13 +419,32 @@ static int at803x_parse_dt(struct phy_device *phydev)
 {
 	struct device_node *node = phydev->mdio.dev.of_node;
 	struct at803x_priv *priv = phydev->priv;
-	u32 freq, strength;
+	u32 freq, strength, tw;
 	unsigned int sel;
 	int ret;
 
 	if (!IS_ENABLED(CONFIG_OF_MDIO))
 		return 0;
 
+	if (of_property_read_bool(node, "qca,disable-smarteee"))
+		priv->flags |= AT803X_DISABLE_SMARTEEE;
+
+	if (!of_property_read_u32(node, "qca,smarteee-tw-us-1g", &tw)) {
+		if (!tw || tw > 255) {
+			phydev_err(phydev, "invalid qca,smarteee-tw-us-1g\n");
+			return -EINVAL;
+		}
+		priv->smarteee_lpi_tw_1g = tw;
+	}
+
+	if (!of_property_read_u32(node, "qca,smarteee-tw-us-100m", &tw)) {
+		if (!tw || tw > 255) {
+			phydev_err(phydev, "invalid qca,smarteee-tw-us-100m\n");
+			return -EINVAL;
+		}
+		priv->smarteee_lpi_tw_100m = tw;
+	}
+
 	ret = of_property_read_u32(node, "qca,clk-out-frequency", &freq);
 	if (!ret) {
 		switch (freq) {
@@ -526,6 +553,38 @@ static void at803x_remove(struct phy_device *phydev)
 		regulator_disable(priv->vddio);
 }
 
+static int at803x_smarteee_config(struct phy_device *phydev)
+{
+	struct at803x_priv *priv = phydev->priv;
+	u16 mask = 0, val = 0;
+	int ret;
+
+	if (priv->flags & AT803X_DISABLE_SMARTEEE)
+		return phy_modify_mmd(phydev, MDIO_MMD_PCS,
+				      AT803X_MMD3_SMARTEEE_CTL3,
+				      AT803X_MMD3_SMARTEEE_CTL3_LPI_EN, 0);
+
+	if (priv->smarteee_lpi_tw_1g) {
+		mask |= 0xff00;
+		val |= priv->smarteee_lpi_tw_1g << 8;
+	}
+	if (priv->smarteee_lpi_tw_100m) {
+		mask |= 0x00ff;
+		val |= priv->smarteee_lpi_tw_100m;
+	}
+	if (!mask)
+		return 0;
+
+	ret = phy_modify_mmd(phydev, MDIO_MMD_PCS, AT803X_MMD3_SMARTEEE_CTL1,
+			     mask, val);
+	if (ret)
+		return ret;
+
+	return phy_modify_mmd(phydev, MDIO_MMD_PCS, AT803X_MMD3_SMARTEEE_CTL3,
+			      AT803X_MMD3_SMARTEEE_CTL3_LPI_EN,
+			      AT803X_MMD3_SMARTEEE_CTL3_LPI_EN);
+}
+
 static int at803x_clk_out_config(struct phy_device *phydev)
 {
 	struct at803x_priv *priv = phydev->priv;
@@ -577,6 +636,10 @@ static int at803x_config_init(struct phy_device *phydev)
 	if (ret < 0)
 		return ret;
 
+	ret = at803x_smarteee_config(phydev);
+	if (ret < 0)
+		return ret;
+
 	ret = at803x_clk_out_config(phydev);
 	if (ret < 0)
 		return ret;