target/linux/generic/backport-5.10/735-v5.14-18-net-dsa-qca8k-dsa-qca8k-protect-MASTER-busy_wait-wit.patch

   1 From 60df02b6ea4581d72eb7a3ab7204504a54059b72 Mon Sep 17 00:00:00 2001
   2 From: Ansuel Smith <ansuelsmth@gmail.com>
   3 Date: Fri, 14 May 2021 23:00:08 +0200
   4 Subject: [PATCH] net: dsa: qca8k: dsa: qca8k: protect MASTER busy_wait with
   5  mdio mutex
   6
   7 MDIO_MASTER operation have a dedicated busy wait that is not protected
   8 by the mdio mutex. This can cause situation where the MASTER operation
   9 is done and a normal operation is executed between the MASTER read/write
  10 and the MASTER busy_wait. Rework the qca8k_mdio_read/write function to
  11 address this issue by binding the lock for the whole MASTER operation
  12 and not only the mdio read/write common operation.
  13
  14 Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
  15 Reviewed-by: Andrew Lunn <andrew@lunn.ch>
  16 Signed-off-by: David S. Miller <davem@davemloft.net>
  17 ---
  18  drivers/net/dsa/qca8k.c | 68 +++++++++++++++++++++++++++++++++--------
  19  1 file changed, 55 insertions(+), 13 deletions(-)
  20
  21 --- a/drivers/net/dsa/qca8k.c
  22 +++ b/drivers/net/dsa/qca8k.c
  23 @@ -628,8 +628,31 @@ qca8k_port_to_phy(int port)
  24  }
  25
  26  static int
  27 +qca8k_mdio_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask)
  28 +{
  29 +       u16 r1, r2, page;
  30 +       u32 val;
  31 +       int ret;
  32 +
  33 +       qca8k_split_addr(reg, &r1, &r2, &page);
  34 +
  35 +       ret = read_poll_timeout(qca8k_mii_read32, val, !(val & mask), 0,
  36 +                               QCA8K_BUSY_WAIT_TIMEOUT * USEC_PER_MSEC, false,
  37 +                               priv->bus, 0x10 | r2, r1);
  38 +
  39 +       /* Check if qca8k_read has failed for a different reason
  40 +        * before returnting -ETIMEDOUT
  41 +        */
  42 +       if (ret < 0 && val < 0)
  43 +               return val;
  44 +
  45 +       return ret;
  46 +}
  47 +
  48 +static int
  49  qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
  50  {
  51 +       u16 r1, r2, page;
  52         u32 phy, val;
  53         int ret;
  54
  55 @@ -645,12 +668,21 @@ qca8k_mdio_write(struct qca8k_priv *priv
  56               QCA8K_MDIO_MASTER_REG_ADDR(regnum) |
  57               QCA8K_MDIO_MASTER_DATA(data);
  58
  59 -       ret = qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val);
  60 +       qca8k_split_addr(QCA8K_MDIO_MASTER_CTRL, &r1, &r2, &page);
  61 +
  62 +       mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
  63 +
  64 +       ret = qca8k_set_page(priv->bus, page);
  65         if (ret)
  66 -               return ret;
  67 +               goto exit;
  68 +
  69 +       qca8k_mii_write32(priv->bus, 0x10 | r2, r1, val);
  70
  71 -       ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
  72 -                             QCA8K_MDIO_MASTER_BUSY);
  73 +       ret = qca8k_mdio_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
  74 +                                  QCA8K_MDIO_MASTER_BUSY);
  75 +
  76 +exit:
  77 +       mutex_unlock(&priv->bus->mdio_lock);
  78
  79         /* even if the busy_wait timeouts try to clear the MASTER_EN */
  80         qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
  81 @@ -662,6 +694,7 @@ qca8k_mdio_write(struct qca8k_priv *priv
  82  static int
  83  qca8k_mdio_read(struct qca8k_priv *priv, int port, u32 regnum)
  84  {
  85 +       u16 r1, r2, page;
  86         u32 phy, val;
  87         int ret;
  88
  89 @@ -676,21 +709,30 @@ qca8k_mdio_read(struct qca8k_priv *priv,
  90               QCA8K_MDIO_MASTER_READ | QCA8K_MDIO_MASTER_PHY_ADDR(phy) |
  91               QCA8K_MDIO_MASTER_REG_ADDR(regnum);
  92
  93 -       ret = qca8k_write(priv, QCA8K_MDIO_MASTER_CTRL, val);
  94 -       if (ret)
  95 -               return ret;
  96 +       qca8k_split_addr(QCA8K_MDIO_MASTER_CTRL, &r1, &r2, &page);
  97 +
  98 +       mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
  99
 100 -       ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
 101 -                             QCA8K_MDIO_MASTER_BUSY);
 102 +       ret = qca8k_set_page(priv->bus, page);
 103         if (ret)
 104 -               return ret;
 105 +               goto exit;
 106
 107 -       val = qca8k_read(priv, QCA8K_MDIO_MASTER_CTRL);
 108 -       if (val < 0)
 109 -               return val;
 110 +       qca8k_mii_write32(priv->bus, 0x10 | r2, r1, val);
 111 +
 112 +       ret = qca8k_mdio_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
 113 +                                  QCA8K_MDIO_MASTER_BUSY);
 114 +       if (ret)
 115 +               goto exit;
 116
 117 +       val = qca8k_mii_read32(priv->bus, 0x10 | r2, r1);
 118         val &= QCA8K_MDIO_MASTER_DATA_MASK;
 119
 120 +exit:
 121 +       mutex_unlock(&priv->bus->mdio_lock);
 122 +
 123 +       if (val >= 0)
 124 +               val &= QCA8K_MDIO_MASTER_DATA_MASK;
 125 +
 126         /* even if the busy_wait timeouts try to clear the MASTER_EN */
 127         qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
 128                         QCA8K_MDIO_MASTER_EN);