[PATCH net-next v20 08/10] net: dsa: mt7530: move MDIO bus locking into regmap

[Christian Marangi]

From: Daniel Golle <daniel at makrotopia.org>

The switch register regmap was created with .disable_locking = true,
relying on callers to manually lock the MDIO bus. Move the locking
into the regmap using .lock/.unlock callbacks, matching the PCS
regmaps that already do this. This allows any code path reaching the
regmap to be automatically protected.

With regmap handling bus locking, the manual mt7530_mutex_lock/unlock
wrappers in mt7530_write(), _mt7530_read(), mt7530_rmw() and
mt7530_port_change_mtu() become redundant and are removed.

The MT7531 indirect PHY access functions need serialization of their
multi-step register sequences, but no longer need to hold bus->mdio_lock
across the whole operation. Switch them to reg_mutex.

core_write()/core_rmw() are the only remaining callers of
mt7530_mutex_lock(). They access TRGMII core PHY registers via the
clause 22 MMD indirect protocol -- a separate register space that
bypasses regmap and needs manual bus->mdio_lock protection.

Generated using the following semantic patch:

// Remove mt7530_mutex_lock/unlock around single regmap-based calls.
@@
expression priv, reg, val;
@@
 {
-	mt7530_mutex_lock(priv);
-
 	mt7530_mii_write(priv, reg, val);
-
-	mt7530_mutex_unlock(priv);
 }

@@
expression priv, reg, mask, set;
@@
 {
-	mt7530_mutex_lock(priv);
-
 	regmap_update_bits(priv->regmap, reg, mask, set);
-
-	mt7530_mutex_unlock(priv);
 }

@@
expression p;
identifier val;
@@
 {
-	u32 val;
-	mt7530_mutex_lock(p->priv);
-	val = mt7530_mii_read(p->priv, p->reg);
-	mt7530_mutex_unlock(p->priv);
-	return val;
+	return mt7530_mii_read(p->priv, p->reg);
 }

@@
expression priv;
@@
-	mt7530_mutex_lock(priv);
 	val = mt7530_mii_read(priv, MT7530_GMACCR);
 	...
 	mt7530_mii_write(priv, MT7530_GMACCR, val);
-	mt7530_mutex_unlock(priv);

@@
expression priv, port;
@@
 	INIT_MT7530_DUMMY_POLL(&p, priv, MT7531_PHY_IAC);
-	mt7530_mutex_lock(priv);
+	mutex_lock(&priv->reg_mutex);

@@
expression priv;
@@
 out:
-	mt7530_mutex_unlock(priv);
+	mutex_unlock(&priv->reg_mutex);

Signed-off-by: Daniel Golle <daniel at makrotopia.org>
Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 drivers/net/dsa/mt7530-mdio.c |  9 ++++++---
 drivers/net/dsa/mt7530.c      | 36 ++++++-----------------------------
 2 files changed, 12 insertions(+), 33 deletions(-)

diff --git a/drivers/net/dsa/mt7530-mdio.c b/drivers/net/dsa/mt7530-mdio.c
index 784dd58a7158..422f785d2143 100644
--- a/drivers/net/dsa/mt7530-mdio.c
+++ b/drivers/net/dsa/mt7530-mdio.c
@@ -148,12 +148,14 @@ static const struct regmap_config regmap_config = {
 	.val_bits = 32,
 	.reg_stride = 4,
 	.max_register = MT7530_CREV,
-	.disable_locking = true,
+	.lock = mt7530_mdio_regmap_lock,
+	.unlock = mt7530_mdio_regmap_unlock,
 };
 
 static int
 mt7530_probe(struct mdio_device *mdiodev)
 {
+	struct regmap_config rc = regmap_config;
 	struct mt7530_priv *priv;
 	struct device_node *dn;
 	int ret;
@@ -207,8 +209,9 @@ mt7530_probe(struct mdio_device *mdiodev)
 			return PTR_ERR(priv->io_pwr);
 	}
 
-	priv->regmap = devm_regmap_init(priv->dev, &mt7530_regmap_bus, priv,
-					&regmap_config);
+	rc.lock_arg = &priv->bus->mdio_lock;
+	priv->regmap = devm_regmap_init(priv->dev, &mt7530_regmap_bus,
+					priv, &rc);
 	if (IS_ERR(priv->regmap))
 		return PTR_ERR(priv->regmap);
 
diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 2b7be091c056..d01772cfe3a2 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -188,29 +188,13 @@ mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
 static int
 mt7530_write(struct mt7530_priv *priv, u32 reg, u32 val)
 {
-	int ret;
-
-	mt7530_mutex_lock(priv);
-
-	ret = mt7530_mii_write(priv, reg, val);
-
-	mt7530_mutex_unlock(priv);
-
-	return ret;
+	return mt7530_mii_write(priv, reg, val);
 }
 
 static u32
 _mt7530_read(struct mt7530_dummy_poll *p)
 {
-	u32 val;
-
-	mt7530_mutex_lock(p->priv);
-
-	val = mt7530_mii_read(p->priv, p->reg);
-
-	mt7530_mutex_unlock(p->priv);
-
-	return val;
+	return mt7530_mii_read(p->priv, p->reg);
 }
 
 static u32
@@ -226,11 +210,7 @@ static void
 mt7530_rmw(struct mt7530_priv *priv, u32 reg,
 	   u32 mask, u32 set)
 {
-	mt7530_mutex_lock(priv);
-
 	regmap_update_bits(priv->regmap, reg, mask, set);
-
-	mt7530_mutex_unlock(priv);
 }
 
 static void
@@ -597,7 +577,7 @@ mt7531_ind_c45_phy_read(struct mt7530_priv *priv, int port, int devad,
 
 	ret = val & MT7531_MDIO_RW_DATA_MASK;
 out:
-	mt7530_mutex_unlock(priv);
+	mutex_unlock(&priv->reg_mutex);
 
 	return ret;
 }
@@ -645,7 +625,7 @@ mt7531_ind_c45_phy_write(struct mt7530_priv *priv, int port, int devad,
 	}
 
 out:
-	mt7530_mutex_unlock(priv);
+	mutex_unlock(&priv->reg_mutex);
 
 	return ret;
 }
@@ -681,7 +661,7 @@ mt7531_ind_c22_phy_read(struct mt7530_priv *priv, int port, int regnum)
 
 	ret = val & MT7531_MDIO_RW_DATA_MASK;
 out:
-	mt7530_mutex_unlock(priv);
+	mutex_unlock(&priv->reg_mutex);
 
 	return ret;
 }
@@ -717,7 +697,7 @@ mt7531_ind_c22_phy_write(struct mt7530_priv *priv, int port, int regnum,
 	}
 
 out:
-	mt7530_mutex_unlock(priv);
+	mutex_unlock(&priv->reg_mutex);
 
 	return ret;
 }
@@ -1452,8 +1432,6 @@ mt7530_port_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
 	if (!dsa_is_cpu_port(ds, port))
 		return 0;
 
-	mt7530_mutex_lock(priv);
-
 	val = mt7530_mii_read(priv, MT7530_GMACCR);
 	val &= ~MAX_RX_PKT_LEN_MASK;
 
@@ -1473,8 +1451,6 @@ mt7530_port_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
 
 	mt7530_mii_write(priv, MT7530_GMACCR, val);
 
-	mt7530_mutex_unlock(priv);
-
 	return 0;
 }
 
-- 
2.53.0