phylib: Allow early-out in phy_change

Marvell 88E1121R Dual PHY device can be hardware-configured
to use shared interrupt pin for both PHY ports. For such
PHY configurations using shared PHY interrupt phy_interrupt()
handler will also schedule a work for PHY port which didn't
cause an interrupt.

This patch adds a possibility for PHY drivers to provide
did_interrupt() function which reports if the PHY (or a PHY
port in a multi-PHY device) generated an interrupt. This
function is called in phy_change() as phy_change() shouldn't
proceed if it is invoked for a PHY which didn't cause an
interrupt. So check for interrupt originator in phy_change()
to allow early-out.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -655,6 +655,10 @@ static void phy_change(struct work_struct *work)
 	struct phy_device *phydev =
 		container_of(work, struct phy_device, phy_queue);
 
+	if (phydev->drv->did_interrupt &&
+	    !phydev->drv->did_interrupt(phydev))
+		goto ignore;
+
 	err = phy_disable_interrupts(phydev);
 
 	if (err)
@@ -681,6 +685,11 @@ static void phy_change(struct work_struct *work)
 
 	return;
 
+ignore:
+	atomic_dec(&phydev->irq_disable);
+	enable_irq(phydev->irq);
+	return;
+
 irq_enable_err:
 	disable_irq(phydev->irq);
 	atomic_inc(&phydev->irq_disable);

include/linux/phy.h

@@ -388,6 +388,12 @@ struct phy_driver {
 	/* Enables or disables interrupts */
 	int (*config_intr)(struct phy_device *phydev);
 
+	/*
+	 * Checks if the PHY generated an interrupt.
+	 * For multi-PHY devices with shared PHY interrupt pin
+	 */
+	int (*did_interrupt)(struct phy_device *phydev);
+
 	/* Clears up any memory if needed */
 	void (*remove)(struct phy_device *phydev);