net: ethernet: fec: Allow configuration of MDIO bus speed

MDIO busses typically operate at 2.5MHz. However many devices can
operate at faster speeds. This then allows more MDIO transactions per
second, useful for Ethernet switch statistics, or Ethernet PHY TDR
data. Allow the bus speed to be configured, using the standard
"clock-frequency" property, which i2c busses use to indicate the bus
speed. Before using this property, ensure all devices on the bus do
actually support the requested clock speed.

Suggested-by: Chris Healy <Chris.Healy@zii.aero>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt
index ff8b0f211aa190ba24a42ec71e8d941e4d2f7f6f..26c492a2e0e109b66a0e1d0e682b838bb5261ea4 100644 (file)
--- a/Documentation/devicetree/bindings/net/fsl-fec.txt
+++ b/Documentation/devicetree/bindings/net/fsl-fec.txt
@@ -82,6 +82,7 @@ ethernet@83fec000 {
        phy-supply = <&reg_fec_supply>;
        phy-handle = <&ethphy>;
        mdio {
+               clock-frequency = <5000000>;
                ethphy: ethernet-phy@6 {
                        compatible = "ethernet-phy-ieee802.3-c22";
                        reg = <6>;

diff --git a/Documentation/devicetree/bindings/net/mdio.yaml b/Documentation/devicetree/bindings/net/mdio.yaml
index 50c3397a82bc4cea8efc364827c4fefb0e0838f8..ab4a9df8b8e2070c1a9805b26583d426a49d0e52 100644 (file)
--- a/Documentation/devicetree/bindings/net/mdio.yaml
+++ b/Documentation/devicetree/bindings/net/mdio.yaml
@@ -39,6 +39,12 @@ properties:
       and must therefore be appropriately determined based on all PHY
       requirements (maximum value of all per-PHY RESET pulse widths).
 
+  clock-frequency:
+    description:
+      Desired MDIO bus clock frequency in Hz. Values greater than IEEE 802.3
+      defined 2.5MHz should only be used when all devices on the bus support
+      the given clock speed.
+
 patternProperties:
   "^ethernet-phy@[0-9a-f]+$":
     type: object

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 2267bf75784eaebaf49c8b10601b9179c9abd9d3..832a24e2805cb9e14d20c8c83588daa78d457853 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2067,6 +2067,7 @@ static int fec_enet_mii_init(struct platform_device *pdev)
        struct device_node *node;
        int err = -ENXIO;
        u32 mii_speed, holdtime;
+       u32 bus_freq;
 
        /*
         * The i.MX28 dual fec interfaces are not equal.
@@ -2094,15 +2095,20 @@ static int fec_enet_mii_init(struct platform_device *pdev)
                return -ENOENT;
        }
 
+       bus_freq = 2500000; /* 2.5MHz by default */
+       node = of_get_child_by_name(pdev->dev.of_node, "mdio");
+       if (node)
+               of_property_read_u32(node, "clock-frequency", &bus_freq);
+
        /*
-        * Set MII speed to 2.5 MHz (= clk_get_rate() / 2 * phy_speed)
+        * Set MII speed (= clk_get_rate() / 2 * phy_speed)
         *
         * The formula for FEC MDC is 'ref_freq / (MII_SPEED x 2)' while
         * for ENET-MAC is 'ref_freq / ((MII_SPEED + 1) x 2)'.  The i.MX28
         * Reference Manual has an error on this, and gets fixed on i.MX6Q
         * document.
         */
-       mii_speed = DIV_ROUND_UP(clk_get_rate(fep->clk_ipg), 5000000);
+       mii_speed = DIV_ROUND_UP(clk_get_rate(fep->clk_ipg), bus_freq * 2);
        if (fep->quirks & FEC_QUIRK_ENET_MAC)
                mii_speed--;
        if (mii_speed > 63) {
@@ -2148,7 +2154,6 @@ static int fec_enet_mii_init(struct platform_device *pdev)
        fep->mii_bus->priv = fep;
        fep->mii_bus->parent = &pdev->dev;
 
-       node = of_get_child_by_name(pdev->dev.of_node, "mdio");
        err = of_mdiobus_register(fep->mii_bus, node);
        of_node_put(node);
        if (err)