net: sfp: Stop SFP polling and interrupt handling during shutdown

SFP device polling can cause problems during the shutdown process if the
parent devices of the network controller have been shut down already.
This problem was seen on the iMX6 platform with PCIe devices, where
accessing the device after the bus is shut down causes a hang.

Free any acquired GPIO interrupts and stop all delayed work in the SFP
driver during the shutdown process, so that we ensure that no pending
operations are still occurring after the SFP shutdown completes.
Signed-off-by: Robert Hancock <hancock@sedsystems.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/sfp.c

@@ -185,6 +185,7 @@ struct sfp {
 	int (*write)(struct sfp *, bool, u8, void *, size_t);
 
 	struct gpio_desc *gpio[GPIO_MAX];
+	int gpio_irq[GPIO_MAX];
 
 	bool attached;
 	unsigned int state;
@@ -1802,7 +1803,7 @@ static int sfp_probe(struct platform_device *pdev)
 	struct i2c_adapter *i2c;
 	struct sfp *sfp;
 	bool poll = false;
-	int irq, err, i;
+	int err, i;
 
 	sfp = sfp_alloc(&pdev->dev);
 	if (IS_ERR(sfp))
@@ -1901,19 +1902,22 @@ static int sfp_probe(struct platform_device *pdev)
 		if (gpio_flags[i] != GPIOD_IN || !sfp->gpio[i])
 			continue;
 
-		irq = gpiod_to_irq(sfp->gpio[i]);
-		if (!irq) {
+		sfp->gpio_irq[i] = gpiod_to_irq(sfp->gpio[i]);
+		if (!sfp->gpio_irq[i]) {
 			poll = true;
 			continue;
 		}
 
-		err = devm_request_threaded_irq(sfp->dev, irq, NULL, sfp_irq,
+		err = devm_request_threaded_irq(sfp->dev, sfp->gpio_irq[i],
+						NULL, sfp_irq,
 						IRQF_ONESHOT |
 						IRQF_TRIGGER_RISING |
 						IRQF_TRIGGER_FALLING,
 						dev_name(sfp->dev), sfp);
-		if (err)
+		if (err) {
+			sfp->gpio_irq[i] = 0;
 			poll = true;
+		}
 	}
 
 	if (poll)
@@ -1944,9 +1948,26 @@ static int sfp_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void sfp_shutdown(struct platform_device *pdev)
+{
+	struct sfp *sfp = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < GPIO_MAX; i++) {
+		if (!sfp->gpio_irq[i])
+			continue;
+
+		devm_free_irq(sfp->dev, sfp->gpio_irq[i], sfp);
+	}
+
+	cancel_delayed_work_sync(&sfp->poll);
+	cancel_delayed_work_sync(&sfp->timeout);
+}
+
 static struct platform_driver sfp_driver = {
 	.probe = sfp_probe,
 	.remove = sfp_remove,
+	.shutdown = sfp_shutdown,
 	.driver = {
 		.name = "sfp",
 		.of_match_table = sfp_of_match,