phy: fix the use of PHY_IGNORE_INTERRUPT

When a PHY device is registered with the special IRQ value
PHY_IGNORE_INTERRUPT (-2) it will not properly be handled by the PHY
library:

- it continues to poll its register, while we do not want this
  because such PHY link events or register changes are serviced by an
  Ethernet MAC
- it will still try to configure PHY interrupts at the PHY level, such
  interrupts do not exist at the PHY but at the MAC level
- the state machine only handles PHY_POLL, but should also handle
  PHY_IGNORE_INTERRUPT similarly

This patch updates the PHY state machine and initialization paths to
account for the specific PHY_IGNORE_INTERRUPT. Based on an earlier patch
by Thomas Petazzoni, and reworked to add the missing bits. Add a helper
phy_interrupt_is_valid() which specifically tests for a PHY interrupt
not to be PHY_POLL or PHY_IGNORE_INTERRUPT and use it throughout the
code.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -682,7 +682,7 @@ void phy_stop(struct phy_device *phydev)
 	if (PHY_HALTED == phydev->state)
 		goto out_unlock;
 
-	if (phydev->irq != PHY_POLL) {
+	if (phy_interrupt_is_valid(phydev)) {
 		/* Disable PHY Interrupts */
 		phy_config_interrupt(phydev, PHY_INTERRUPT_DISABLED);
 
@@ -828,8 +828,9 @@ void phy_state_machine(struct work_struct *work)
 			break;
 		case PHY_RUNNING:
 			/* Only register a CHANGE if we are
-			 * polling */
-			if (PHY_POLL == phydev->irq)
+			 * polling or ignoring interrupts
+			 */
+			if (!phy_interrupt_is_valid(phydev))
 				phydev->state = PHY_CHANGELINK;
 			break;
 		case PHY_CHANGELINK:
@@ -848,7 +849,7 @@ void phy_state_machine(struct work_struct *work)
 
 			phydev->adjust_link(phydev->attached_dev);
 
-			if (PHY_POLL != phydev->irq)
+			if (phy_interrupt_is_valid(phydev))
 				err = phy_config_interrupt(phydev,
 						PHY_INTERRUPT_ENABLED);
 			break;

drivers/net/phy/phy_device.c

@@ -1009,8 +1009,11 @@ static int phy_probe(struct device *dev)
 	phydrv = to_phy_driver(drv);
 	phydev->drv = phydrv;
 
-	/* Disable the interrupt if the PHY doesn't support it */
-	if (!(phydrv->flags & PHY_HAS_INTERRUPT))
+	/* Disable the interrupt if the PHY doesn't support it
+	 * but the interrupt is still a valid one
+	 */
+	if (!(phydrv->flags & PHY_HAS_INTERRUPT) &&
+			phy_interrupt_is_valid(phydev))
 		phydev->irq = PHY_POLL;
 
 	mutex_lock(&phydev->lock);

include/linux/phy.h

@@ -508,6 +508,18 @@ static inline int phy_write(struct phy_device *phydev, u32 regnum, u16 val)
 	return mdiobus_write(phydev->bus, phydev->addr, regnum, val);
 }
 
+/**
+ * phy_interrupt_is_valid - Convenience function for testing a given PHY irq
+ * @phydev: the phy_device struct
+ *
+ * NOTE: must be kept in sync with addition/removal of PHY_POLL and
+ * PHY_IGNORE_INTERRUPT
+ */
+static inline bool phy_interrupt_is_valid(struct phy_device *phydev)
+{
+	return phydev->irq != PHY_POLL && phydev->irq != PHY_IGNORE_INTERRUPT;
+}
+
 struct phy_device *phy_device_create(struct mii_bus *bus, int addr, int phy_id,
 		bool is_c45, struct phy_c45_device_ids *c45_ids);
 struct phy_device *get_phy_device(struct mii_bus *bus, int addr, bool is_c45);