Merge branch 'mdiobus_nested_read_write'

Neil Armstrong says:

====================
Refactor nested mdiobus read/write functions

In order to avoid locked signal false positive for nested mdiobus
read/write calls, nested code was introduced in mv88e6xxx and
mdio-mux.
But mv88e6060 also needs such nested mdiobus read/write calls.
For sake of refactoring, introduce nested variants of mdiobus read/write
and make them used by mv88e6xxx and mv88e6060.
In a next patch, mdio-mux should also use these variant calls.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 68 insertions, 39 deletions

diff --git a/drivers/net/dsa/mv88e6060.c b/drivers/net/dsa/mv88e6060.c
index c29aebe1e62b..9093577755f6 100644
--- a/drivers/net/dsa/mv88e6060.c
+++ b/drivers/net/dsa/mv88e6060.c
@@ -26,7 +26,7 @@ static int reg_read(struct dsa_switch *ds, int addr, int reg)
 	if (bus == NULL)
 		return -EINVAL;
 
-	return mdiobus_read(bus, ds->pd->sw_addr + addr, reg);
+	return mdiobus_read_nested(bus, ds->pd->sw_addr + addr, reg);
 }
 
 #define REG_READ(addr, reg)					\
@@ -47,7 +47,7 @@ static int reg_write(struct dsa_switch *ds, int addr, int reg, u16 val)
 	if (bus == NULL)
 		return -EINVAL;
 
-	return mdiobus_write(bus, ds->pd->sw_addr + addr, reg, val);
+	return mdiobus_write_nested(bus, ds->pd->sw_addr + addr, reg, val);
 }
 
 #define REG_WRITE(addr, reg, val)				\
diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
index 7af96309bc07..b1b14f519d8b 100644
--- a/drivers/net/dsa/mv88e6xxx.c
+++ b/drivers/net/dsa/mv88e6xxx.c
@@ -24,34 +24,6 @@
 #include <net/switchdev.h>
 #include "mv88e6xxx.h"
 
-/* MDIO bus access can be nested in the case of PHYs connected to the
- * internal MDIO bus of the switch, which is accessed via MDIO bus of
- * the Ethernet interface. Avoid lockdep false positives by using
- * mutex_lock_nested().
- */
-static int mv88e6xxx_mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
-{
-	int ret;
-
-	mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING);
-	ret = bus->read(bus, addr, regnum);
-	mutex_unlock(&bus->mdio_lock);
-
-	return ret;
-}
-
-static int mv88e6xxx_mdiobus_write(struct mii_bus *bus, int addr, u32 regnum,
-				   u16 val)
-{
-	int ret;
-
-	mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING);
-	ret = bus->write(bus, addr, regnum, val);
-	mutex_unlock(&bus->mdio_lock);
-
-	return ret;
-}
-
 /* If the switch's ADDR[4:0] strap pins are strapped to zero, it will
  * use all 32 SMI bus addresses on its SMI bus, and all switch registers
  * will be directly accessible on some {device address,register address}
@@ -66,7 +38,7 @@ static int mv88e6xxx_reg_wait_ready(struct mii_bus *bus, int sw_addr)
 	int i;
 
 	for (i = 0; i < 16; i++) {
-		ret = mv88e6xxx_mdiobus_read(bus, sw_addr, SMI_CMD);
+		ret = mdiobus_read_nested(bus, sw_addr, SMI_CMD);
 		if (ret < 0)
 			return ret;
 
@@ -82,7 +54,7 @@ int __mv88e6xxx_reg_read(struct mii_bus *bus, int sw_addr, int addr, int reg)
 	int ret;
 
 	if (sw_addr == 0)
-		return mv88e6xxx_mdiobus_read(bus, addr, reg);
+		return mdiobus_read_nested(bus, addr, reg);
 
 	/* Wait for the bus to become free. */
 	ret = mv88e6xxx_reg_wait_ready(bus, sw_addr);
@@ -90,8 +62,8 @@ int __mv88e6xxx_reg_read(struct mii_bus *bus, int sw_addr, int addr, int reg)
 		return ret;
 
 	/* Transmit the read command. */
-	ret = mv88e6xxx_mdiobus_write(bus, sw_addr, SMI_CMD,
-				      SMI_CMD_OP_22_READ | (addr << 5) | reg);
+	ret = mdiobus_write_nested(bus, sw_addr, SMI_CMD,
+				   SMI_CMD_OP_22_READ | (addr << 5) | reg);
 	if (ret < 0)
 		return ret;
 
@@ -101,7 +73,7 @@ int __mv88e6xxx_reg_read(struct mii_bus *bus, int sw_addr, int addr, int reg)
 		return ret;
 
 	/* Read the data. */
-	ret = mv88e6xxx_mdiobus_read(bus, sw_addr, SMI_DATA);
+	ret = mdiobus_read_nested(bus, sw_addr, SMI_DATA);
 	if (ret < 0)
 		return ret;
 
@@ -145,7 +117,7 @@ int __mv88e6xxx_reg_write(struct mii_bus *bus, int sw_addr, int addr,
 	int ret;
 
 	if (sw_addr == 0)
-		return mv88e6xxx_mdiobus_write(bus, addr, reg, val);
+		return mdiobus_write_nested(bus, addr, reg, val);
 
 	/* Wait for the bus to become free. */
 	ret = mv88e6xxx_reg_wait_ready(bus, sw_addr);
@@ -153,13 +125,13 @@ int __mv88e6xxx_reg_write(struct mii_bus *bus, int sw_addr, int addr,
 		return ret;
 
 	/* Transmit the data to write. */
-	ret = mv88e6xxx_mdiobus_write(bus, sw_addr, SMI_DATA, val);
+	ret = mdiobus_write_nested(bus, sw_addr, SMI_DATA, val);
 	if (ret < 0)
 		return ret;
 
 	/* Transmit the write command. */
-	ret = mv88e6xxx_mdiobus_write(bus, sw_addr, SMI_CMD,
-				      SMI_CMD_OP_22_WRITE | (addr << 5) | reg);
+	ret = mdiobus_write_nested(bus, sw_addr, SMI_CMD,
+				   SMI_CMD_OP_22_WRITE | (addr << 5) | reg);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 12f44c53cc8e..88cb4592b6fb 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -372,6 +372,33 @@ struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
 EXPORT_SYMBOL(mdiobus_scan);
 
 /**
+ * mdiobus_read_nested - Nested version of the mdiobus_read function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to read
+ *
+ * In case of nested MDIO bus access avoid lockdep false positives by
+ * using mutex_lock_nested().
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ */
+int mdiobus_read_nested(struct mii_bus *bus, int addr, u32 regnum)
+{
+	int retval;
+
+	BUG_ON(in_interrupt());
+
+	mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING);
+	retval = bus->read(bus, addr, regnum);
+	mutex_unlock(&bus->mdio_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL(mdiobus_read_nested);
+
+/**
  * mdiobus_read - Convenience function for reading a given MII mgmt register
  * @bus: the mii_bus struct
  * @addr: the phy address
@@ -396,6 +423,34 @@ int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 EXPORT_SYMBOL(mdiobus_read);
 
 /**
+ * mdiobus_write_nested - Nested version of the mdiobus_write function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @val: value to write to @regnum
+ *
+ * In case of nested MDIO bus access avoid lockdep false positives by
+ * using mutex_lock_nested().
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ */
+int mdiobus_write_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val)
+{
+	int err;
+
+	BUG_ON(in_interrupt());
+
+	mutex_lock_nested(&bus->mdio_lock, SINGLE_DEPTH_NESTING);
+	err = bus->write(bus, addr, regnum, val);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(mdiobus_write_nested);
+
+/**
  * mdiobus_write - Convenience function for writing a given MII mgmt register
  * @bus: the mii_bus struct
  * @addr: the phy address
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 4c477e6ece33..05fde31b6dc6 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -213,7 +213,9 @@ static inline struct mii_bus *devm_mdiobus_alloc(struct device *dev)
 void devm_mdiobus_free(struct device *dev, struct mii_bus *bus);
 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
 int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum);
+int mdiobus_read_nested(struct mii_bus *bus, int addr, u32 regnum);
 int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val);
+int mdiobus_write_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val);
 
 
 #define PHY_INTERRUPT_DISABLED	0x0