net: phy: bcm7xx: add jumbo frame configuration to PHY

The BCM7XX PHY family requires special configuration to pass jumbo
frames. Do that during initial PHY setup.

Signed-off-by: Murali Krishna Policharla <murali.policharla@broadcom.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/phy/bcm-phy-lib.c b/drivers/net/phy/bcm-phy-lib.c
index e0d3310..e77b274 100644
--- a/drivers/net/phy/bcm-phy-lib.c
+++ b/drivers/net/phy/bcm-phy-lib.c
@@ -423,6 +423,28 @@ int bcm_phy_28nm_a0b0_afe_config_init(struct phy_device *phydev)
 }
 EXPORT_SYMBOL_GPL(bcm_phy_28nm_a0b0_afe_config_init);
 
+int bcm_phy_enable_jumbo(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = bcm54xx_auxctl_read(phydev, MII_BCM54XX_AUXCTL_SHDWSEL_AUXCTL);
+	if (ret < 0)
+		return ret;
+
+	/* Enable extended length packet reception */
+	ret = bcm54xx_auxctl_write(phydev, MII_BCM54XX_AUXCTL_SHDWSEL_AUXCTL,
+				   ret | MII_BCM54XX_AUXCTL_ACTL_EXT_PKT_LEN);
+	if (ret < 0)
+		return ret;
+
+	/* Enable the elastic FIFO for raising the transmission limit from
+	 * 4.5KB to 10KB, at the expense of an additional 16 ns in propagation
+	 * latency.
+	 */
+	return phy_set_bits(phydev, MII_BCM54XX_ECR, MII_BCM54XX_ECR_FIFOE);
+}
+EXPORT_SYMBOL_GPL(bcm_phy_enable_jumbo);
+
 MODULE_DESCRIPTION("Broadcom PHY Library");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Broadcom Corporation");
diff --git a/drivers/net/phy/bcm-phy-lib.h b/drivers/net/phy/bcm-phy-lib.h
index c86fb9d1..129df81 100644
--- a/drivers/net/phy/bcm-phy-lib.h
+++ b/drivers/net/phy/bcm-phy-lib.h
@@ -65,5 +65,6 @@ void bcm_phy_get_stats(struct phy_device *phydev, u64 *shadow,
 		       struct ethtool_stats *stats, u64 *data);
 void bcm_phy_r_rc_cal_reset(struct phy_device *phydev);
 int bcm_phy_28nm_a0b0_afe_config_init(struct phy_device *phydev);
+int bcm_phy_enable_jumbo(struct phy_device *phydev);
 
 #endif /* _LINUX_BCM_PHY_LIB_H */
diff --git a/drivers/net/phy/bcm7xxx.c b/drivers/net/phy/bcm7xxx.c
index af8eabe..692048d 100644
--- a/drivers/net/phy/bcm7xxx.c
+++ b/drivers/net/phy/bcm7xxx.c
@@ -181,6 +181,10 @@ static int bcm7xxx_28nm_config_init(struct phy_device *phydev)
 	if (ret)
 		return ret;
 
+	ret =  bcm_phy_enable_jumbo(phydev);
+	if (ret)
+		return ret;
+
 	ret = bcm_phy_downshift_get(phydev, &count);
 	if (ret)
 		return ret;