net: phy: dp83867: Validate FIFO depth property

Insure property is in valid range and fail when reading DT if it is not.
Also add error message for existing failure if required property is not
present.

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NTrent Piepho <tpiepho@impinj.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/dp83867.c

@@ -65,7 +65,8 @@
 
 /* PHY CTRL bits */
 #define DP83867_PHYCR_FIFO_DEPTH_SHIFT		14
-#define DP83867_PHYCR_FIFO_DEPTH_MASK		(3 << 14)
+#define DP83867_PHYCR_FIFO_DEPTH_MAX		0x03
+#define DP83867_PHYCR_FIFO_DEPTH_MASK		GENMASK(15, 14)
 #define DP83867_PHYCR_RESERVED_MASK		BIT(11)
 
 /* RGMIIDCTL bits */
@@ -245,8 +246,20 @@ static int dp83867_of_init(struct phy_device *phydev)
 	if (of_property_read_bool(of_node, "enet-phy-lane-no-swap"))
 		dp83867->port_mirroring = DP83867_PORT_MIRROING_DIS;
 
-	return of_property_read_u32(of_node, "ti,fifo-depth",
+	ret = of_property_read_u32(of_node, "ti,fifo-depth",
 				   &dp83867->fifo_depth);
+	if (ret) {
+		phydev_err(phydev,
+			   "ti,fifo-depth property is required\n");
+		return ret;
+	}
+	if (dp83867->fifo_depth > DP83867_PHYCR_FIFO_DEPTH_MAX) {
+		phydev_err(phydev,
+			   "ti,fifo-depth value %u out of range\n",
+			   dp83867->fifo_depth);
+		return -EINVAL;
+	}
+	return 0;
 }
 #else
 static int dp83867_of_init(struct phy_device *phydev)