net: dsa: vsc73xx: check busy flag in MDIO operations

The VSC73xx has a busy flag used during MDIO operations. It is raised
when MDIO read/write operations are in progress. Without it, PHYs are
misconfigured and bus operations do not work as expected.

Fixes: 05bd97fc559d ("net: dsa: Add Vitesse VSC73xx DSA router driver")
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index 4b300c293dec47d5c031e174ee641afde1ad140c..a789b2da9b7d4af4a1f0c5beb9257eefe6c92b13 100644 (file)
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -40,6 +40,10 @@
 #define VSC73XX_BLOCK_ARBITER  0x5 /* Only subblock 0 */
 #define VSC73XX_BLOCK_SYSTEM   0x7 /* Only subblock 0 */
 
+/* MII Block subblock */
+#define VSC73XX_BLOCK_MII_INTERNAL     0x0 /* Internal MDIO subblock */
+#define VSC73XX_BLOCK_MII_EXTERNAL     0x1 /* External MDIO subblock */
+
 #define CPU_PORT       6 /* CPU port */
 
 /* MAC Block registers */
@@ -225,6 +229,8 @@
 #define VSC73XX_MII_CMD                0x1
 #define VSC73XX_MII_DATA       0x2
 
+#define VSC73XX_MII_STAT_BUSY  BIT(3)
+
 /* Arbiter block 5 registers */
 #define VSC73XX_ARBEMPTY               0x0c
 #define VSC73XX_ARBDISC                        0x0e
@@ -299,6 +305,7 @@
 #define IS_739X(a) (IS_7395(a) || IS_7398(a))
 
 #define VSC73XX_POLL_SLEEP_US          1000
+#define VSC73XX_MDIO_POLL_SLEEP_US     5
 #define VSC73XX_POLL_TIMEOUT_US                10000
 
 struct vsc73xx_counter {
@@ -527,6 +534,22 @@ static int vsc73xx_detect(struct vsc73xx *vsc)
        return 0;
 }
 
+static int vsc73xx_mdio_busy_check(struct vsc73xx *vsc)
+{
+       int ret, err;
+       u32 val;
+
+       ret = read_poll_timeout(vsc73xx_read, err,
+                               err < 0 || !(val & VSC73XX_MII_STAT_BUSY),
+                               VSC73XX_MDIO_POLL_SLEEP_US,
+                               VSC73XX_POLL_TIMEOUT_US, false, vsc,
+                               VSC73XX_BLOCK_MII, VSC73XX_BLOCK_MII_INTERNAL,
+                               VSC73XX_MII_STAT, &val);
+       if (ret)
+               return ret;
+       return err;
+}
+
 static int vsc73xx_phy_read(struct dsa_switch *ds, int phy, int regnum)
 {
        struct vsc73xx *vsc = ds->priv;
@@ -534,12 +557,20 @@ static int vsc73xx_phy_read(struct dsa_switch *ds, int phy, int regnum)
        u32 val;
        int ret;
 
+       ret = vsc73xx_mdio_busy_check(vsc);
+       if (ret)
+               return ret;
+
        /* Setting bit 26 means "read" */
        cmd = BIT(26) | (phy << 21) | (regnum << 16);
        ret = vsc73xx_write(vsc, VSC73XX_BLOCK_MII, 0, 1, cmd);
        if (ret)
                return ret;
-       msleep(2);
+
+       ret = vsc73xx_mdio_busy_check(vsc);
+       if (ret)
+               return ret;
+
        ret = vsc73xx_read(vsc, VSC73XX_BLOCK_MII, 0, 2, &val);
        if (ret)
                return ret;
@@ -563,6 +594,10 @@ static int vsc73xx_phy_write(struct dsa_switch *ds, int phy, int regnum,
        u32 cmd;
        int ret;
 
+       ret = vsc73xx_mdio_busy_check(vsc);
+       if (ret)
+               return ret;
+
        /* It was found through tedious experiments that this router
         * chip really hates to have it's PHYs reset. They
         * never recover if that happens: autonegotiation stops