net: phy: Add nested variants of mdiobus read/write

Since nested variants of mdiobus_read/write are used in multiple
drivers, add nested variants in the mdiobus core.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 12f44c53cc8ebca7cba92119c26b01b249e31846..88cb4592b6fbbc6cc1ed6812b0fad2d17885a17e 100644 (file)
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -371,6 +371,33 @@ 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
@@ -395,6 +422,34 @@ 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

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 4c477e6ece33356530da3d38210df2820d2be04d..05fde31b6dc6dbe2f97356cea09a961dc1cd3af0 100644 (file)
--- 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