net: dsa: qca8k: dsa: qca8k: protect MASTER busy_wait with mdio mutex

MDIO_MASTER operation have a dedicated busy wait that is not protected
by the mdio mutex. This can cause situation where the MASTER operation
is done and a normal operation is executed between the MASTER read/write
and the MASTER busy_wait. Rework the qca8k_mdio_read/write function to
address this issue by binding the lock for the whole MASTER operation
and not only the mdio read/write common operation.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index a2b4d50..1f8bfe0 100644 (file)
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -628,8 +628,31 @@ qca8k_port_to_phy(int port)
 }
 
 static int
+qca8k_mdio_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask)
+{
+       u16 r1, r2, page;
+       u32 val;
+       int ret;
+
+       qca8k_split_addr(reg, &r1, &r2, &page);
+
+       ret = read_poll_timeout(qca8k_mii_read32, val, !(val & mask), 0,
+                               QCA8K_BUSY_WAIT_TIMEOUT * USEC_PER_MSEC, false,
+                               priv->bus, 0x10 | r2, r1);
+
+       /* Check if qca8k_read has failed for a different reason
+        * before returnting -ETIMEDOUT
+        */
+       if (ret < 0 && val < 0)
+               return val;
+
+       return ret;
+}
+
+static int
 qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
 {
+       u16 r1, r2, page;
        u32 phy, val;
        int ret;
 
@@ -645,12 +668,21 @@ qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
              QCA8K_MDIO_MASTER_REG_ADDR(regnum) |
              QCA8K_MDIO_MASTER_DATA(data);
 
-       ret = qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val);
+       qca8k_split_addr(QCA8K_MDIO_MASTER_CTRL, &r1, &r2, &page);
+
+       mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
+
+       ret = qca8k_set_page(priv->bus, page);
        if (ret)
-               return ret;
+               goto exit;
+
+       qca8k_mii_write32(priv->bus, 0x10 | r2, r1, val);
 
-       ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
-                             QCA8K_MDIO_MASTER_BUSY);
+       ret = qca8k_mdio_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
+                                  QCA8K_MDIO_MASTER_BUSY);
+
+exit:
+       mutex_unlock(&priv->bus->mdio_lock);
 
        /* even if the busy_wait timeouts try to clear the MASTER_EN */
        qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
@@ -662,6 +694,7 @@ qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
 static int
 qca8k_mdio_read(struct qca8k_priv *priv, int port, u32 regnum)
 {
+       u16 r1, r2, page;
        u32 phy, val;
        int ret;
 
@@ -676,21 +709,30 @@ qca8k_mdio_read(struct qca8k_priv *priv, int port, u32 regnum)
              QCA8K_MDIO_MASTER_READ | QCA8K_MDIO_MASTER_PHY_ADDR(phy) |
              QCA8K_MDIO_MASTER_REG_ADDR(regnum);
 
-       ret = qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val);
-       if (ret)
-               return ret;
+       qca8k_split_addr(QCA8K_MDIO_MASTER_CTRL, &r1, &r2, &page);
 
-       ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
-                             QCA8K_MDIO_MASTER_BUSY);
+       mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
+
+       ret = qca8k_set_page(priv->bus, page);
        if (ret)
-               return ret;
+               goto exit;
 
-       val = qca8k_read(priv, QCA8K_MDIO_MASTER_CTRL);
-       if (val < 0)
-               return val;
+       qca8k_mii_write32(priv->bus, 0x10 | r2, r1, val);
 
+       ret = qca8k_mdio_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
+                                  QCA8K_MDIO_MASTER_BUSY);
+       if (ret)
+               goto exit;
+
+       val = qca8k_mii_read32(priv->bus, 0x10 | r2, r1);
        val &= QCA8K_MDIO_MASTER_DATA_MASK;
 
+exit:
+       mutex_unlock(&priv->bus->mdio_lock);
+
+       if (val >= 0)
+               val &= QCA8K_MDIO_MASTER_DATA_MASK;
+
        /* even if the busy_wait timeouts try to clear the MASTER_EN */
        qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
                        QCA8K_MDIO_MASTER_EN);