[netdrvr] gianfar: Determine TBIPA value dynamically

TBIPA needs to be set to a value (on connected MDIO buses) that
doesn't conflict with PHYs on the bus.  By hardcoding it to 0x1f,
we were preventing boards with PHYs at 0x1f from working properly.
Instead, scan the bus when it comes up, and find an address that
doesn't have a PHY on it.  The TBI PHY configuration code then
trusts that the value in TBIPA is either safe, or doesn't matter
(ie - it's not an active bus with other PHYs).

Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 33 insertions, 5 deletions

diff --git a/drivers/net/gianfar_mii.c b/drivers/net/gianfar_mii.c
index b8898927236a..ebcfb27a904e 100644
--- a/drivers/net/gianfar_mii.c
+++ b/drivers/net/gianfar_mii.c
@@ -78,7 +78,6 @@ int gfar_local_mdio_write(struct gfar_mii __iomem *regs, int mii_id,
  * same as system mdio bus, used for controlling the external PHYs, for eg.
  */
 int gfar_local_mdio_read(struct gfar_mii __iomem *regs, int mii_id, int regnum)
-
 {
         u16 value;
 
@@ -122,7 +121,7 @@ int gfar_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
 }
 
 /* Reset the MIIM registers, and wait for the bus to free */
-int gfar_mdio_reset(struct mii_bus *bus)
+static int gfar_mdio_reset(struct mii_bus *bus)
 {
         struct gfar_mii __iomem *regs = (void __iomem *)bus->priv;
         unsigned int timeout = PHY_INIT_TIMEOUT;
@@ -152,14 +151,15 @@ int gfar_mdio_reset(struct mii_bus *bus)
 }
 
 
-int gfar_mdio_probe(struct device *dev)
+static int gfar_mdio_probe(struct device *dev)
 {
         struct platform_device *pdev = to_platform_device(dev);
         struct gianfar_mdio_data *pdata;
         struct gfar_mii __iomem *regs;
+        struct gfar __iomem *enet_regs;
         struct mii_bus *new_bus;
         struct resource *r;
-        int err = 0;
+        int i, err = 0;
 
         if (NULL == dev)
                 return -EINVAL;
@@ -199,6 +199,34 @@ int gfar_mdio_probe(struct device *dev)
         new_bus->dev = dev;
         dev_set_drvdata(dev, new_bus);
 
+        /*
+         * This is mildly evil, but so is our hardware for doing this.
+         * Also, we have to cast back to struct gfar_mii because of
+         * definition weirdness done in gianfar.h.
+         */
+        enet_regs = (struct gfar __iomem *)
+                ((char *)regs - offsetof(struct gfar, gfar_mii_regs));
+
+        /* Scan the bus, looking for an empty spot for TBIPA */
+        gfar_write(&enet_regs->tbipa, 0);
+        for (i = PHY_MAX_ADDR; i > 0; i--) {
+                u32 phy_id;
+                int r;
+
+                r = get_phy_id(new_bus, i, &phy_id);
+                if (r)
+                        return r;
+
+                if (phy_id == 0xffffffff)
+                        break;
+        }
+
+        /* The bus is full.  We don't support using 31 PHYs, sorry */
+        if (i == 0)
+                return -EBUSY;
+
+        gfar_write(&enet_regs->tbipa, i);
+
         err = mdiobus_register(new_bus);
 
         if (0 != err) {
@@ -218,7 +246,7 @@ reg_map_fail:
 }
 
 
-int gfar_mdio_remove(struct device *dev)
+static int gfar_mdio_remove(struct device *dev)
 {
         struct mii_bus *bus = dev_get_drvdata(dev);