[RFC PATCH net 1/2] net: mdio: introduce a shutdown method to mdio device drivers

[Vladimir Oltean]

MDIO devices might have interrupts and other things that might need
quiesced when we kexec into a new kernel. Things are even more creepy
when those interrupt lines are shared, and in that case it is absolutely
mandatory to disable all interrupt sources.

Moreover, MDIO devices might be DSA switches, and DSA needs its own
shutdown method to unlink from the DSA master.

So introduce a ->shutdown method in the MDIO device driver structure.

Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
---
 drivers/net/phy/mdio_device.c | 11 +++++++++++
 include/linux/mdio.h          |  3 +++
 2 files changed, 14 insertions(+)

diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
index c94cb5382dc9..250742ffdfd9 100644
--- a/drivers/net/phy/mdio_device.c
+++ b/drivers/net/phy/mdio_device.c
@@ -179,6 +179,16 @@ static int mdio_remove(struct device *dev)
 	return 0;
 }
 
+static void mdio_shutdown(struct device *dev)
+{
+	struct mdio_device *mdiodev = to_mdio_device(dev);
+	struct device_driver *drv = mdiodev->dev.driver;
+	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
+
+	if (mdiodrv->shutdown)
+		mdiodrv->shutdown(mdiodev);
+}
+
 /**
  * mdio_driver_register - register an mdio_driver with the MDIO layer
  * @drv: new mdio_driver to register
@@ -193,6 +203,7 @@ int mdio_driver_register(struct mdio_driver *drv)
 	mdiodrv->driver.bus = &mdio_bus_type;
 	mdiodrv->driver.probe = mdio_probe;
 	mdiodrv->driver.remove = mdio_remove;
+	mdiodrv->driver.shutdown = mdio_shutdown;
 
 	retval = driver_register(&mdiodrv->driver);
 	if (retval) {
diff --git a/include/linux/mdio.h b/include/linux/mdio.h
index ffb787d5ebde..5e6dc38f418e 100644
--- a/include/linux/mdio.h
+++ b/include/linux/mdio.h
@@ -80,6 +80,9 @@ struct mdio_driver {
 
 	/* Clears up any memory if needed */
 	void (*remove)(struct mdio_device *mdiodev);
+
+	/* Quiesces the device on system shutdown, turns off interrupts etc */
+	void (*shutdown)(struct mdio_device *mdiodev);
 };
 
 static inline struct mdio_driver *
-- 
2.25.1


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