usb: typec: Link enumerated USB devices with Type-C partner

Adding functions that USB hub code can use to inform the
Type-C class about connected USB devices.

Once taken into use, it will allow the Type-C port drivers
to power off components that are not needed, for example if
USB2 device is enumerated, everything that is only relevant
for USB3 (retimers, etc.), can be powered off.

This will also create a symlink "typec" for the USB devices
pointing to the USB Type-C partner device.

Suggested-by: Benson Leung <bleung@chromium.org>
Tested-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20231011105825.320062-2-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 100 insertions, 8 deletions

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 9c1dbf3c00e0..2e0451bd336e 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -13,6 +13,7 @@
 #include <linux/usb/pd_vdo.h>
 #include <linux/usb/typec_mux.h>
 #include <linux/usb/typec_retimer.h>
+#include <linux/usb.h>
 
 #include "bus.h"
 #include "class.h"
@@ -681,6 +682,33 @@ const struct device_type typec_partner_dev_type = {
 	.release = typec_partner_release,
 };
 
+static void typec_partner_link_device(struct typec_partner *partner, struct device *dev)
+{
+	int ret;
+
+	ret = sysfs_create_link(&dev->kobj, &partner->dev.kobj, "typec");
+	if (ret)
+		return;
+
+	ret = sysfs_create_link(&partner->dev.kobj, &dev->kobj, dev_name(dev));
+	if (ret) {
+		sysfs_remove_link(&dev->kobj, "typec");
+		return;
+	}
+
+	if (partner->attach)
+		partner->attach(partner, dev);
+}
+
+static void typec_partner_unlink_device(struct typec_partner *partner, struct device *dev)
+{
+	sysfs_remove_link(&partner->dev.kobj, dev_name(dev));
+	sysfs_remove_link(&dev->kobj, "typec");
+
+	if (partner->deattach)
+		partner->deattach(partner, dev);
+}
+
 /**
  * typec_partner_set_identity - Report result from Discover Identity command
  * @partner: The partner updated identity values
@@ -865,6 +893,8 @@ struct typec_partner *typec_register_partner(struct typec_port *port,
 	partner->num_altmodes = -1;
 	partner->pd_revision = desc->pd_revision;
 	partner->svdm_version = port->cap->svdm_version;
+	partner->attach = desc->attach;
+	partner->deattach = desc->deattach;
 
 	if (desc->identity) {
 		/*
@@ -887,6 +917,11 @@ struct typec_partner *typec_register_partner(struct typec_port *port,
 		return ERR_PTR(ret);
 	}
 
+	if (port->usb2_dev)
+		typec_partner_link_device(partner, port->usb2_dev);
+	if (port->usb3_dev)
+		typec_partner_link_device(partner, port->usb3_dev);
+
 	return partner;
 }
 EXPORT_SYMBOL_GPL(typec_register_partner);
@@ -899,8 +934,19 @@ EXPORT_SYMBOL_GPL(typec_register_partner);
  */
 void typec_unregister_partner(struct typec_partner *partner)
 {
-	if (!IS_ERR_OR_NULL(partner))
-		device_unregister(&partner->dev);
+	struct typec_port *port;
+
+	if (IS_ERR_OR_NULL(partner))
+		return;
+
+	port = to_typec_port(partner->dev.parent);
+
+	if (port->usb2_dev)
+		typec_partner_unlink_device(partner, port->usb2_dev);
+	if (port->usb3_dev)
+		typec_partner_unlink_device(partner, port->usb3_dev);
+
+	device_unregister(&partner->dev);
 }
 EXPORT_SYMBOL_GPL(typec_unregister_partner);
 
@@ -1775,6 +1821,50 @@ static int partner_match(struct device *dev, void *data)
 	return is_typec_partner(dev);
 }
 
+static struct typec_partner *typec_get_partner(struct typec_port *port)
+{
+	struct device *dev;
+
+	dev = device_find_child(&port->dev, NULL, partner_match);
+	if (!dev)
+		return NULL;
+
+	return to_typec_partner(dev);
+}
+
+static void typec_partner_attach(struct typec_connector *con, struct device *dev)
+{
+	struct typec_port *port = container_of(con, struct typec_port, con);
+	struct typec_partner *partner = typec_get_partner(port);
+	struct usb_device *udev = to_usb_device(dev);
+
+	if (udev->speed < USB_SPEED_SUPER)
+		port->usb2_dev = dev;
+	else
+		port->usb3_dev = dev;
+
+	if (partner) {
+		typec_partner_link_device(partner, dev);
+		put_device(&partner->dev);
+	}
+}
+
+static void typec_partner_deattach(struct typec_connector *con, struct device *dev)
+{
+	struct typec_port *port = container_of(con, struct typec_port, con);
+	struct typec_partner *partner = typec_get_partner(port);
+
+	if (partner) {
+		typec_partner_unlink_device(partner, dev);
+		put_device(&partner->dev);
+	}
+
+	if (port->usb2_dev == dev)
+		port->usb2_dev = NULL;
+	else if (port->usb3_dev == dev)
+		port->usb3_dev = NULL;
+}
+
 /**
  * typec_set_data_role - Report data role change
  * @port: The USB Type-C Port where the role was changed
@@ -1784,7 +1874,7 @@ static int partner_match(struct device *dev, void *data)
  */
 void typec_set_data_role(struct typec_port *port, enum typec_data_role role)
 {
-	struct device *partner_dev;
+	struct typec_partner *partner;
 
 	if (port->data_role == role)
 		return;
@@ -1793,14 +1883,14 @@ void typec_set_data_role(struct typec_port *port, enum typec_data_role role)
 	sysfs_notify(&port->dev.kobj, NULL, "data_role");
 	kobject_uevent(&port->dev.kobj, KOBJ_CHANGE);
 
-	partner_dev = device_find_child(&port->dev, NULL, partner_match);
-	if (!partner_dev)
+	partner = typec_get_partner(port);
+	if (!partner)
 		return;
 
-	if (to_typec_partner(partner_dev)->identity)
-		typec_product_type_notify(partner_dev);
+	if (partner->identity)
+		typec_product_type_notify(&partner->dev);
 
-	put_device(partner_dev);
+	put_device(&partner->dev);
 }
 EXPORT_SYMBOL_GPL(typec_set_data_role);
 
@@ -2251,6 +2341,8 @@ struct typec_port *typec_register_port(struct device *parent,
 	port->ops = cap->ops;
 	port->port_type = cap->type;
 	port->prefer_role = cap->prefer_role;
+	port->con.attach = typec_partner_attach;
+	port->con.deattach = typec_partner_deattach;
 
 	device_initialize(&port->dev);
 	port->dev.class = &typec_class;