dp83640: Ensure against premature access to PHY registers after reset

[ Upstream commit 76327a35caabd1a932e83d6a42b967aa08584e5d ]

The datasheet specifies a 3uS pause after performing a software
reset. The default implementation of genphy_soft_reset() does not
provide this, so implement soft_reset with the needed pause.

Signed-off-by: Esben Haabendal <eha@deif.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
index b88f7d65953d3efba82f0131e57ae5e065b8ca7e..482ea404a2d464360495d790db5ccced98cbc27c 100644 (file)
--- a/drivers/net/phy/dp83640.c
+++ b/drivers/net/phy/dp83640.c
@@ -1205,6 +1205,23 @@ static void dp83640_remove(struct phy_device *phydev)
        kfree(dp83640);
 }
 
+static int dp83640_soft_reset(struct phy_device *phydev)
+{
+       int ret;
+
+       ret = genphy_soft_reset(phydev);
+       if (ret < 0)
+               return ret;
+
+       /* From DP83640 datasheet: "Software driver code must wait 3 us
+        * following a software reset before allowing further serial MII
+        * operations with the DP83640."
+        */
+       udelay(10);             /* Taking udelay inaccuracy into account */
+
+       return 0;
+}
+
 static int dp83640_config_init(struct phy_device *phydev)
 {
        struct dp83640_private *dp83640 = phydev->priv;
@@ -1498,6 +1515,7 @@ static struct phy_driver dp83640_driver = {
        .flags          = PHY_HAS_INTERRUPT,
        .probe          = dp83640_probe,
        .remove         = dp83640_remove,
+       .soft_reset     = dp83640_soft_reset,
        .config_init    = dp83640_config_init,
        .config_aneg    = genphy_config_aneg,
        .read_status    = genphy_read_status,