board: verdin-imx8mm: Add KSZ9131 phy skew settings

This patch basically just enables both RXC and TXC delay lines in the
PHY. This will compensate the missing delay from the MAC. Other skew
settings are not needed as the traces on board are routed exactly the
same length

Related-to: ELB-1299
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

2 files changed, 55 insertions, 22 deletions

diff --git a/board/toradex/verdin-imx8mm/verdin-imx8mm.c b/board/toradex/verdin-imx8mm/verdin-imx8mm.c
index 1edae1e545..56d1490166 100644
--- a/board/toradex/verdin-imx8mm/verdin-imx8mm.c
+++ b/board/toradex/verdin-imx8mm/verdin-imx8mm.c
@@ -100,28 +100,57 @@ static int setup_fec(void)
 
 int board_phy_config(struct phy_device *phydev)
 {
-/*
- * The PHY adds 1.2ns for the RXC and 0ns for TXC clock by default. The MAC
- * and the layout don't add a skew between clock and data.
- * Add 0.3ns for the RXC path and 0.96 + 0.42 ns (1.38 ns) for the TXC path
- * to get the required clock skews.
- */
-	/* control data pad skew - devaddr = 0x02, register = 0x04 */
-	ksz9031_phy_extended_write(phydev, 0x02,
-				   MII_KSZ9031_EXT_RGMII_CTRL_SIG_SKEW,
-				   MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x0070);
-	/* rx data pad skew - devaddr = 0x02, register = 0x05 */
-	ksz9031_phy_extended_write(phydev, 0x02,
-				   MII_KSZ9031_EXT_RGMII_RX_DATA_SKEW,
-				   MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x7777);
-	/* tx data pad skew - devaddr = 0x02, register = 0x06 */
-	ksz9031_phy_extended_write(phydev, 0x02,
-				   MII_KSZ9031_EXT_RGMII_TX_DATA_SKEW,
-				   MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x0000);
-	/* gtx and rx clock pad skew - devaddr = 0x02, register = 0x08 */
-	ksz9031_phy_extended_write(phydev, 0x02,
-				   MII_KSZ9031_EXT_RGMII_CLOCK_SKEW,
-				   MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x03f4);
+	int tmp;
+
+	switch(ksz9xx1_phy_get_id(phydev) & MII_KSZ9x31_SILICON_REV_MASK) {
+	case PHY_ID_KSZ9031:
+		/*
+		* The PHY adds 1.2ns for the RXC and 0ns for TXC clock by default. The MAC
+		* and the layout don't add a skew between clock and data.
+		* Add 0.3ns for the RXC path and 0.96 + 0.42 ns (1.38 ns) for the TXC path
+		* to get the required clock skews.
+		*/
+		/* control data pad skew - devaddr = 0x02, register = 0x04 */
+		ksz9031_phy_extended_write(phydev, 0x02,
+					MII_KSZ9031_EXT_RGMII_CTRL_SIG_SKEW,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x0070);
+		/* rx data pad skew - devaddr = 0x02, register = 0x05 */
+		ksz9031_phy_extended_write(phydev, 0x02,
+					MII_KSZ9031_EXT_RGMII_RX_DATA_SKEW,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x7777);
+		/* tx data pad skew - devaddr = 0x02, register = 0x06 */
+		ksz9031_phy_extended_write(phydev, 0x02,
+					MII_KSZ9031_EXT_RGMII_TX_DATA_SKEW,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x0000);
+		/* gtx and rx clock pad skew - devaddr = 0x02, register = 0x08 */
+		ksz9031_phy_extended_write(phydev, 0x02,
+					MII_KSZ9031_EXT_RGMII_CLOCK_SKEW,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x03f4);
+		break;
+	case PHY_ID_KSZ9131:
+	default:
+		/* read rxc dll control - devaddr = 0x2, register = 0x4c */
+		tmp = ksz9031_phy_extended_read(phydev, 0x02,
+					MII_KSZ9131_EXT_RGMII_2NS_SKEW_RXDLL,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC);
+		/* disable rxdll bypass (enable 2ns skew delay on RXC) */
+		tmp &= ~MII_KSZ9131_RXTXDLL_BYPASS;
+		/* rxc data pad skew 2ns - devaddr = 0x02, register = 0x4c */
+		tmp = ksz9031_phy_extended_write(phydev, 0x02,
+					MII_KSZ9131_EXT_RGMII_2NS_SKEW_RXDLL,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC, tmp);
+		/* read txc dll control - devaddr = 0x02, register = 0x4d */
+		tmp = ksz9031_phy_extended_read(phydev, 0x02,
+					MII_KSZ9131_EXT_RGMII_2NS_SKEW_TXDLL,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC);
+		/* disable txdll bypass (enable 2ns skew delay on TXC) */
+		tmp &= ~MII_KSZ9131_RXTXDLL_BYPASS;
+		/* rxc data pad skew 2ns - devaddr = 0x02, register = 0x4d */
+		tmp = ksz9031_phy_extended_write(phydev, 0x02,
+					MII_KSZ9131_EXT_RGMII_2NS_SKEW_TXDLL,
+					MII_KSZ9031_MOD_DATA_NO_POST_INC, tmp);
+		break;
+	}
 
 	if (phydev->drv->config)
 		phydev->drv->config(phydev);
diff --git a/include/micrel.h b/include/micrel.h
index f5126f2992..a2593c5b10 100644
--- a/include/micrel.h
+++ b/include/micrel.h
@@ -25,6 +25,10 @@
 
 #define MII_KSZ9x31_SILICON_REV_MASK		0xfffff0
 
+#define MII_KSZ9131_RXTXDLL_BYPASS		BIT(12)
+#define MII_KSZ9131_EXT_RGMII_2NS_SKEW_RXDLL	0x4c
+#define MII_KSZ9131_EXT_RGMII_2NS_SKEW_TXDLL	0x4d
+
 #define PHY_ID_KSZ9031				0x00221620
 #define PHY_ID_KSZ9131				0x00221640