lxt PHY: Support for the buggy LXT973 rev A2

This patch adds proper handling of the buggy revision A2 of LXT973 phy, adding
precautions linked to ERRATA Item 4:

Revision A2 of LXT973 chip randomly returns the contents of the previous even
register when you read a odd register regularly

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/lxt.c b/drivers/net/phy/lxt.c
index 6d1e3fc..ec40ba8 100644 (file)
--- a/drivers/net/phy/lxt.c
+++ b/drivers/net/phy/lxt.c
@@ -122,6 +122,123 @@ static int lxt971_config_intr(struct phy_device *phydev)
        return err;
 }
 
+/*
+ * A2 version of LXT973 chip has an ERRATA: it randomly return the contents
+ * of the previous even register when you read a odd register regularly
+ */
+
+static int lxt973a2_update_link(struct phy_device *phydev)
+{
+       int status;
+       int control;
+       int retry = 8; /* we try 8 times */
+
+       /* Do a fake read */
+       status = phy_read(phydev, MII_BMSR);
+
+       if (status < 0)
+               return status;
+
+       control = phy_read(phydev, MII_BMCR);
+       if (control < 0)
+               return control;
+
+       do {
+               /* Read link and autonegotiation status */
+               status = phy_read(phydev, MII_BMSR);
+       } while (status >= 0 && retry-- && status == control);
+
+       if (status < 0)
+               return status;
+
+       if ((status & BMSR_LSTATUS) == 0)
+               phydev->link = 0;
+       else
+               phydev->link = 1;
+
+       return 0;
+}
+
+int lxt973a2_read_status(struct phy_device *phydev)
+{
+       int adv;
+       int err;
+       int lpa;
+       int lpagb = 0;
+
+       /* Update the link, but return if there was an error */
+       err = lxt973a2_update_link(phydev);
+       if (err)
+               return err;
+
+       if (AUTONEG_ENABLE == phydev->autoneg) {
+               int retry = 1;
+
+               adv = phy_read(phydev, MII_ADVERTISE);
+
+               if (adv < 0)
+                       return adv;
+
+               do {
+                       lpa = phy_read(phydev, MII_LPA);
+
+                       if (lpa < 0)
+                               return lpa;
+
+                       /* If both registers are equal, it is suspect but not
+                       * impossible, hence a new try
+                       */
+               } while (lpa == adv && retry--);
+
+               lpa &= adv;
+
+               phydev->speed = SPEED_10;
+               phydev->duplex = DUPLEX_HALF;
+               phydev->pause = phydev->asym_pause = 0;
+
+               if (lpagb & (LPA_1000FULL | LPA_1000HALF)) {
+                       phydev->speed = SPEED_1000;
+
+                       if (lpagb & LPA_1000FULL)
+                               phydev->duplex = DUPLEX_FULL;
+               } else if (lpa & (LPA_100FULL | LPA_100HALF)) {
+                       phydev->speed = SPEED_100;
+
+                       if (lpa & LPA_100FULL)
+                               phydev->duplex = DUPLEX_FULL;
+               } else {
+                       if (lpa & LPA_10FULL)
+                               phydev->duplex = DUPLEX_FULL;
+               }
+
+               if (phydev->duplex == DUPLEX_FULL) {
+                       phydev->pause = lpa & LPA_PAUSE_CAP ? 1 : 0;
+                       phydev->asym_pause = lpa & LPA_PAUSE_ASYM ? 1 : 0;
+               }
+       } else {
+               int bmcr = phy_read(phydev, MII_BMCR);
+
+               if (bmcr < 0)
+                       return bmcr;
+
+               if (bmcr & BMCR_FULLDPLX)
+                       phydev->duplex = DUPLEX_FULL;
+               else
+                       phydev->duplex = DUPLEX_HALF;
+
+               if (bmcr & BMCR_SPEED1000)
+                       phydev->speed = SPEED_1000;
+               else if (bmcr & BMCR_SPEED100)
+                       phydev->speed = SPEED_100;
+               else
+                       phydev->speed = SPEED_10;
+
+               phydev->pause = phydev->asym_pause = 0;
+       }
+
+       return 0;
+}
+
 static int lxt973_probe(struct phy_device *phydev)
 {
        int val = phy_read(phydev, MII_LXT973_PCR);
@@ -175,6 +292,16 @@ static struct phy_driver lxt97x_driver[] = {
        .driver         = { .owner = THIS_MODULE,},
 }, {
        .phy_id         = 0x00137a10,
+       .name           = "LXT973-A2",
+       .phy_id_mask    = 0xffffffff,
+       .features       = PHY_BASIC_FEATURES,
+       .flags          = 0,
+       .probe          = lxt973_probe,
+       .config_aneg    = lxt973_config_aneg,
+       .read_status    = lxt973a2_read_status,
+       .driver         = { .owner = THIS_MODULE,},
+}, {
+       .phy_id         = 0x00137a10,
        .name           = "LXT973",
        .phy_id_mask    = 0xfffffff0,
        .features       = PHY_BASIC_FEATURES,