usb: typec: altmode: Remove the notification chain

Using the generic notification chain is not reasonable with
the alternate modes because it would require dependencies
between the drivers of the components that need the
notifications, and the typec drivers.

There are no users for the alternate mode notifications, so
removing the chain and the API for it completely.

Signed-off-by: Heikki Krogerus <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/driver-api/usb/typec_bus.rst

···
 needs to notify the bus using :c:func:`typec_altmode_notify()`. The driver
 passes the negotiated SVID specific pin configuration value to the function as
 parameter. The bus driver will then configure the mux behind the connector using
-that value as the state value for the mux, and also call blocking notification
-chain to notify the external drivers about the state of the connector that need
-to know it.
+that value as the state value for the mux.
 
 NOTE: The SVID specific pin configuration values must always start from
 ``TYPEC_STATE_MODAL``. USB Type-C specification defines two default states for
···
 
 #define ALTMODEX_CONF_A = TYPEC_MODAL_STATE(0);
 #define ALTMODEX_CONF_B = TYPEC_MODAL_STATE(1);
-
-Notification chain
-~~~~~~~~~~~~~~~~~~
-
-The drivers for the components that the alternate modes are designed for need to
-get details regarding the results of the negotiation with the partner, and the
-pin configuration of the connector. In case of DisplayPort alternate mode for
-example, the GPU drivers will need to know those details. In case of
-Thunderbolt alternate mode, the thunderbolt drivers will need to know them, and
-so on.
-
-The notification chain is designed for this purpose. The drivers can register
-notifiers with :c:func:`typec_altmode_register_notifier()`.
 
 Cable plug alternate modes
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
···
 
 .. kernel-doc:: drivers/usb/typec/bus.c
    :functions: typec_altmode_get_plug typec_altmode_put_plug
-
-Notifications
-~~~~~~~~~~~~~
-.. kernel-doc:: drivers/usb/typec/class.c
-   :functions: typec_altmode_register_notifier typec_altmode_unregister_notifier

drivers/usb/typec/bus.c

···
 {
 	bool is_port = is_typec_port(adev->dev.parent);
 	struct altmode *port_altmode;
-	int ret;
 
 	port_altmode = is_port ? to_altmode(adev) : to_altmode(adev)->partner;
 
-	ret = typec_altmode_set_mux(port_altmode, conf, data);
-	if (ret)
-		return ret;
-
-	blocking_notifier_call_chain(&port_altmode->nh, conf, NULL);
-
-	return 0;
+	return typec_altmode_set_mux(port_altmode, conf, data);
 }
 
 /* -------------------------------------------------------------------------- */
···
 	ret = typec_altmode_set_mux(is_port ? altmode : partner, conf, data);
 	if (ret)
 		return ret;
-
-	blocking_notifier_call_chain(is_port ? &altmode->nh : &partner->nh,
-				     conf, data);
 
 	if (partner->adev.ops && partner->adev.ops->notify)
 		return partner->adev.ops->notify(&partner->adev, conf, data);

drivers/usb/typec/bus.h

···
 
 	struct altmode			*partner;
 	struct altmode			*plug[2];
-
-	struct blocking_notifier_head	nh;
 };
 
 #define to_altmode(d) container_of(d, struct altmode, adev)

drivers/usb/typec/class.c

···
 	put_device(&adev->dev);
 }
 
-static void *typec_port_match(struct device_connection *con, int ep, void *data)
-{
-	struct device *dev;
-
-	/*
-	 * FIXME: Check does the fwnode supports the requested SVID. If it does
-	 * we need to return ERR_PTR(-PROBE_DEFER) when there is no device.
-	 */
-	if (con->fwnode)
-		return class_find_device_by_fwnode(typec_class, con->fwnode);
-
-	dev = class_find_device_by_name(typec_class, con->endpoint[ep]);
-
-	return dev ? dev : ERR_PTR(-EPROBE_DEFER);
-}
-
-struct typec_altmode *
-typec_altmode_register_notifier(struct device *dev, u16 svid, u8 mode,
-				struct notifier_block *nb)
-{
-	struct typec_device_id id = { svid, mode, };
-	struct device *altmode_dev;
-	struct device *port_dev;
-	struct altmode *altmode;
-	int ret;
-
-	/* Find the port linked to the caller */
-	port_dev = device_connection_find_match(dev, NULL, NULL,
-						typec_port_match);
-	if (IS_ERR_OR_NULL(port_dev))
-		return port_dev ? ERR_CAST(port_dev) : ERR_PTR(-ENODEV);
-
-	/* Find the altmode with matching svid */
-	altmode_dev = device_find_child(port_dev, &id, altmode_match);
-
-	put_device(port_dev);
-
-	if (!altmode_dev)
-		return ERR_PTR(-ENODEV);
-
-	altmode = to_altmode(to_typec_altmode(altmode_dev));
-
-	/* Register notifier */
-	ret = blocking_notifier_chain_register(&altmode->nh, nb);
-	if (ret) {
-		put_device(altmode_dev);
-		return ERR_PTR(ret);
-	}
-
-	return &altmode->adev;
-}
-EXPORT_SYMBOL_GPL(typec_altmode_register_notifier);
-
-void typec_altmode_unregister_notifier(struct typec_altmode *adev,
-				       struct notifier_block *nb)
-{
-	struct altmode *altmode = to_altmode(adev);
-
-	blocking_notifier_chain_unregister(&altmode->nh, nb);
-	put_device(&adev->dev);
-}
-EXPORT_SYMBOL_GPL(typec_altmode_unregister_notifier);
-
 /**
  * typec_altmode_update_active - Report Enter/Exit mode
  * @adev: Handle to the alternate mode
···
 	dev_set_name(&alt->adev.dev, "%s.%u", dev_name(parent), id);
 
 	/* Link partners and plugs with the ports */
-	if (is_port)
-		BLOCKING_INIT_NOTIFIER_HEAD(&alt->nh);
-	else
+	if (!is_port)
 		typec_altmode_set_partner(alt);
 
 	/* The partners are bind to drivers */

include/linux/usb/typec_altmode.h

···
 struct typec_altmode *typec_match_altmode(struct typec_altmode **altmodes,
 					  size_t n, u16 svid, u8 mode);
 
-struct typec_altmode *
-typec_altmode_register_notifier(struct device *dev, u16 svid, u8 mode,
-				struct notifier_block *nb);
-
-void typec_altmode_unregister_notifier(struct typec_altmode *adev,
-				       struct notifier_block *nb);
-
 /**
  * typec_altmode_get_orientation - Get cable plug orientation
  * altmode: Handle to the alternate mode