net: mdiobus: add APIs for modifying a MDIO device register

Add APIs for modifying a MDIO device register, similar to the existing
phy_modify() group of functions, but at mdiobus level instead.  Adapt
__phy_modify_changed() to use the new mdiobus level helper.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 9bb9f37f21dc..587eb5663d34 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -808,6 +808,38 @@ int __mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 EXPORT_SYMBOL(__mdiobus_write);
 
 /**
+ * __mdiobus_modify_changed - Unlocked version of the mdiobus_modify function
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ *
+ * Read, modify, and if any change, write the register value back to the
+ * device. Any error returns a negative number.
+ *
+ * NOTE: MUST NOT be called from interrupt context.
+ */
+int __mdiobus_modify_changed(struct mii_bus *bus, int addr, u32 regnum,
+			     u16 mask, u16 set)
+{
+	int new, ret;
+
+	ret = __mdiobus_read(bus, addr, regnum);
+	if (ret < 0)
+		return ret;
+
+	new = (ret & ~mask) | set;
+	if (new == ret)
+		return 0;
+
+	ret = __mdiobus_write(bus, addr, regnum, new);
+
+	return ret < 0 ? ret : 1;
+}
+EXPORT_SYMBOL_GPL(__mdiobus_modify_changed);
+
+/**
  * mdiobus_read_nested - Nested version of the mdiobus_read function
  * @bus: the mii_bus struct
  * @addr: the phy address
@@ -912,6 +944,29 @@ int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 EXPORT_SYMBOL(mdiobus_write);
 
 /**
+ * mdiobus_modify - Convenience function for modifying a given mdio device
+ *	register
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int mdiobus_modify(struct mii_bus *bus, int addr, u32 regnum, u16 mask, u16 set)
+{
+	int err;
+
+	BUG_ON(in_interrupt());
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_modify_changed(bus, addr, regnum, mask, set);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err < 0 ? err : 0;
+}
+EXPORT_SYMBOL_GPL(mdiobus_modify);
+
+/**
  * mdio_bus_match - determine if given MDIO driver supports the given
  *		    MDIO device
  * @dev: target MDIO device