net: phy: Allow BCM5481x PHYs to setup internal TX/RX clock delay

This patch allows users to enable/disable internal TX and/or RX
clock delay for BCM5481x series PHYs so as to satisfy RGMII timing
specifications.

On a particular platform, whether TX and/or RX clock delay is required
depends on how PHY connected to the MAC IP. This requirement can be
specified through "phy-mode" property in the platform device tree.
Signed-off-by: Abhishek Shah <abhishek.shah@broadcom.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/broadcom.c

@@ -74,27 +74,40 @@ static int bcm54612e_config_init(struct phy_device *phydev)
 	return 0;
 }
 
-static int bcm54810_config(struct phy_device *phydev)
+static int bcm5481x_config(struct phy_device *phydev)
 {
 	int rc, val;
 
-	val = bcm_phy_read_exp(phydev, BCM54810_EXP_BROADREACH_LRE_MISC_CTL);
-	val &= ~BCM54810_EXP_BROADREACH_LRE_MISC_CTL_EN;
-	rc = bcm_phy_write_exp(phydev, BCM54810_EXP_BROADREACH_LRE_MISC_CTL,
-			       val);
-	if (rc < 0)
-		return rc;
-
+	/* handling PHY's internal RX clock delay */
 	val = bcm54xx_auxctl_read(phydev, MII_BCM54XX_AUXCTL_SHDWSEL_MISC);
-	val &= ~MII_BCM54XX_AUXCTL_SHDWSEL_MISC_RGMII_SKEW_EN;
 	val |= MII_BCM54XX_AUXCTL_MISC_WREN;
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
+		/* Disable RGMII RXC-RXD skew */
+		val &= ~MII_BCM54XX_AUXCTL_SHDWSEL_MISC_RGMII_SKEW_EN;
+	}
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
+		/* Enable RGMII RXC-RXD skew */
+		val |= MII_BCM54XX_AUXCTL_SHDWSEL_MISC_RGMII_SKEW_EN;
+	}
 	rc = bcm54xx_auxctl_write(phydev, MII_BCM54XX_AUXCTL_SHDWSEL_MISC,
 				  val);
 	if (rc < 0)
 		return rc;
 
+	/* handling PHY's internal TX clock delay */
 	val = bcm_phy_read_shadow(phydev, BCM54810_SHD_CLK_CTL);
-	val &= ~BCM54810_SHD_CLK_CTL_GTXCLK_EN;
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
+		/* Disable internal TX clock delay */
+		val &= ~BCM54810_SHD_CLK_CTL_GTXCLK_EN;
+	}
+	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	    phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
+		/* Enable internal TX clock delay */
+		val |= BCM54810_SHD_CLK_CTL_GTXCLK_EN;
+	}
 	rc = bcm_phy_write_shadow(phydev, BCM54810_SHD_CLK_CTL, val);
 	if (rc < 0)
 		return rc;
@@ -244,7 +257,7 @@ static void bcm54xx_adjust_rxrefclk(struct phy_device *phydev)
 
 static int bcm54xx_config_init(struct phy_device *phydev)
 {
-	int reg, err;
+	int reg, err, val;
 
 	reg = phy_read(phydev, MII_BCM54XX_ECR);
 	if (reg < 0)
@@ -283,8 +296,14 @@ static int bcm54xx_config_init(struct phy_device *phydev)
 		if (err)
 			return err;
 	} else if (BRCM_PHY_MODEL(phydev) == PHY_ID_BCM54810) {
-		err = bcm54810_config(phydev);
-		if (err)
+		/* For BCM54810, we need to disable BroadR-Reach function */
+		val = bcm_phy_read_exp(phydev,
+				       BCM54810_EXP_BROADREACH_LRE_MISC_CTL);
+		val &= ~BCM54810_EXP_BROADREACH_LRE_MISC_CTL_EN;
+		err = bcm_phy_write_exp(phydev,
+					BCM54810_EXP_BROADREACH_LRE_MISC_CTL,
+					val);
+		if (err < 0)
 			return err;
 	}
 
@@ -392,29 +411,7 @@ static int bcm5481_config_aneg(struct phy_device *phydev)
 	ret = genphy_config_aneg(phydev);
 
 	/* Then we can set up the delay. */
-	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
-		u16 reg;
-
-		/*
-		 * There is no BCM5481 specification available, so down
-		 * here is everything we know about "register 0x18". This
-		 * at least helps BCM5481 to successfully receive packets
-		 * on MPC8360E-RDK board. Peter Barada <peterb@logicpd.com>
-		 * says: "This sets delay between the RXD and RXC signals
-		 * instead of using trace lengths to achieve timing".
-		 */
-
-		/* Set RDX clk delay. */
-		reg = 0x7 | (0x7 << 12);
-		phy_write(phydev, 0x18, reg);
-
-		reg = phy_read(phydev, 0x18);
-		/* Set RDX-RXC skew. */
-		reg |= (1 << 8);
-		/* Write bits 14:0. */
-		reg |= (1 << 15);
-		phy_write(phydev, 0x18, reg);
-	}
+	bcm5481x_config(phydev);
 
 	if (of_property_read_bool(np, "enet-phy-lane-swap")) {
 		/* Lane Swap - Undocumented register...magic! */