1 files changed, 118 insertions, 9 deletions

diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
index 7d6aad287f84..cdea028d1328 100644
--- a/drivers/net/phy/phy-core.c
+++ b/drivers/net/phy/phy-core.c
@@ -531,7 +531,7 @@ int phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
 EXPORT_SYMBOL(phy_write_mmd);
 
 /**
- * __phy_modify() - Convenience function for modifying a PHY register
+ * __phy_modify_changed() - Convenience function for modifying a PHY register
  * @phydev: a pointer to a &struct phy_device
  * @regnum: register number
  * @mask: bit mask of bits to clear
@@ -539,16 +539,69 @@ EXPORT_SYMBOL(phy_write_mmd);
  *
  * Unlocked helper function which allows a PHY register to be modified as
  * new register value = (old register value & ~mask) | set
+ *
+ * Returns negative errno, 0 if there was no change, and 1 in case of change
  */
-int __phy_modify(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
+int __phy_modify_changed(struct phy_device *phydev, u32 regnum, u16 mask,
+			 u16 set)
 {
-	int ret;
+	int new, ret;
 
 	ret = __phy_read(phydev, regnum);
 	if (ret < 0)
 		return ret;
 
-	ret = __phy_write(phydev, regnum, (ret & ~mask) | set);
+	new = (ret & ~mask) | set;
+	if (new == ret)
+		return 0;
+
+	ret = __phy_write(phydev, regnum, new);
+
+	return ret < 0 ? ret : 1;
+}
+EXPORT_SYMBOL_GPL(__phy_modify_changed);
+
+/**
+ * phy_modify_changed - Function for modifying a PHY register
+ * @phydev: the phy_device struct
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: new value of bits set in mask to write to @regnum
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ *
+ * Returns negative errno, 0 if there was no change, and 1 in case of change
+ */
+int phy_modify_changed(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
+{
+	int ret;
+
+	mutex_lock(&phydev->mdio.bus->mdio_lock);
+	ret = __phy_modify_changed(phydev, regnum, mask, set);
+	mutex_unlock(&phydev->mdio.bus->mdio_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phy_modify_changed);
+
+/**
+ * __phy_modify - Convenience function for modifying a PHY register
+ * @phydev: the phy_device struct
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: new value of bits set in mask to write to @regnum
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ */
+int __phy_modify(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
+{
+	int ret;
+
+	ret = __phy_modify_changed(phydev, regnum, mask, set);
 
 	return ret < 0 ? ret : 0;
 }
@@ -578,7 +631,7 @@ int phy_modify(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
 EXPORT_SYMBOL_GPL(phy_modify);
 
 /**
- * __phy_modify_mmd - Convenience function for modifying a register on MMD
+ * __phy_modify_mmd_changed - Function for modifying a register on MMD
  * @phydev: the phy_device struct
  * @devad: the MMD containing register to modify
  * @regnum: register number to modify
@@ -587,17 +640,73 @@ EXPORT_SYMBOL_GPL(phy_modify);
  *
  * Unlocked helper function which allows a MMD register to be modified as
  * new register value = (old register value & ~mask) | set
+ *
+ * Returns negative errno, 0 if there was no change, and 1 in case of change
  */
-int __phy_modify_mmd(struct phy_device *phydev, int devad, u32 regnum,
-		     u16 mask, u16 set)
+int __phy_modify_mmd_changed(struct phy_device *phydev, int devad, u32 regnum,
+			     u16 mask, u16 set)
 {
-	int ret;
+	int new, ret;
 
 	ret = __phy_read_mmd(phydev, devad, regnum);
 	if (ret < 0)
 		return ret;
 
-	ret = __phy_write_mmd(phydev, devad, regnum, (ret & ~mask) | set);
+	new = (ret & ~mask) | set;
+	if (new == ret)
+		return 0;
+
+	ret = __phy_write_mmd(phydev, devad, regnum, new);
+
+	return ret < 0 ? ret : 1;
+}
+EXPORT_SYMBOL_GPL(__phy_modify_mmd_changed);
+
+/**
+ * phy_modify_mmd_changed - Function for modifying a register on MMD
+ * @phydev: the phy_device struct
+ * @devad: the MMD containing register to modify
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: new value of bits set in mask to write to @regnum
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ *
+ * Returns negative errno, 0 if there was no change, and 1 in case of change
+ */
+int phy_modify_mmd_changed(struct phy_device *phydev, int devad, u32 regnum,
+			   u16 mask, u16 set)
+{
+	int ret;
+
+	mutex_lock(&phydev->mdio.bus->mdio_lock);
+	ret = __phy_modify_mmd_changed(phydev, devad, regnum, mask, set);
+	mutex_unlock(&phydev->mdio.bus->mdio_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phy_modify_mmd_changed);
+
+/**
+ * __phy_modify_mmd - Convenience function for modifying a register on MMD
+ * @phydev: the phy_device struct
+ * @devad: the MMD containing register to modify
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: new value of bits set in mask to write to @regnum
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ */
+int __phy_modify_mmd(struct phy_device *phydev, int devad, u32 regnum,
+		     u16 mask, u16 set)
+{
+	int ret;
+
+	ret = __phy_modify_mmd_changed(phydev, devad, regnum, mask, set);
 
 	return ret < 0 ? ret : 0;
 }