greybus: core: defer connection creation to driver probe

Defer connection creation to bundle driver probe instead of creating
them when initialising the interface and parsing the manifest.

Store copies of the CPorts descriptors in the bundle for the drivers to
use, and update the legacy driver.

This is needed for drivers that need more control over host-device
resource management, for example, when a protocol needs to use a
dedicated host CPort for traffic offloading (e.g. camera data).

This also avoids allocating host CPorts for bundles that are not bound
to a driver or for remote CPorts that a driver does not need.

Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/bundle.c

@@ -81,15 +81,9 @@ static struct gb_bundle *gb_bundle_find(struct gb_interface *intf,
 static void gb_bundle_release(struct device *dev)
 {
 	struct gb_bundle *bundle = to_gb_bundle(dev);
-	struct gb_connection *connection;
-	struct gb_connection *tmp;
-
-	list_for_each_entry_safe(connection, tmp, &bundle->connections,
-								bundle_links) {
-		gb_connection_destroy(connection);
-	}
 
 	kfree(bundle->state);
+	kfree(bundle->cport_desc);
 	kfree(bundle);
 }
 

drivers/staging/greybus/bundle.h

@@ -22,6 +22,9 @@ struct gb_bundle {
 	u8			class_major;
 	u8			class_minor;
 
+	size_t			num_cports;
+	struct greybus_descriptor_cport *cport_desc;
+
 	struct list_head	connections;
 	u8			*state;
 

drivers/staging/greybus/connection.c

@@ -232,6 +232,7 @@ gb_connection_create_dynamic(struct gb_interface *intf,
 	return gb_connection_create(intf->hd, -1, intf, bundle, cport_id,
 								protocol_id);
 }
+EXPORT_SYMBOL_GPL(gb_connection_create_dynamic);
 
 static int gb_connection_hd_cport_enable(struct gb_connection *connection)
 {
@@ -546,6 +547,7 @@ void gb_connection_destroy(struct gb_connection *connection)
 
 	gb_connection_put(connection);
 }
+EXPORT_SYMBOL_GPL(gb_connection_destroy);
 
 void gb_connection_latency_tag_enable(struct gb_connection *connection)
 {

drivers/staging/greybus/core.c

@@ -151,8 +151,14 @@ static int greybus_probe(struct device *dev)
 		return -ENODEV;
 
 	retval = driver->probe(bundle, id);
-	if (retval)
+	if (retval) {
+		/*
+		 * Catch buggy drivers that fail to destroy their connections.
+		 */
+		WARN_ON(!list_empty(&bundle->connections));
+
 		return retval;
+	}
 
 	return 0;
 }
@@ -172,11 +178,8 @@ static int greybus_remove(struct device *dev)
 
 	driver->disconnect(bundle);
 
-	/* Catch buggy drivers that fail to disable their connections. */
-	list_for_each_entry(connection, &bundle->connections, bundle_links) {
-		if (WARN_ON(connection->state != GB_CONNECTION_STATE_DISABLED))
-			gb_connection_disable(connection);
-	}
+	/* Catch buggy drivers that fail to destroy their connections. */
+	WARN_ON(!list_empty(&bundle->connections));
 
 	return 0;
 }

drivers/staging/greybus/legacy.c

@@ -14,6 +14,7 @@
 
 struct legacy_data {
 	size_t num_cports;
+	struct gb_connection **connections;
 };
 
 
@@ -128,25 +129,44 @@ static void legacy_connection_exit(struct gb_connection *connection)
 static int legacy_probe(struct gb_bundle *bundle,
 			const struct greybus_bundle_id *id)
 {
+	struct greybus_descriptor_cport *cport_desc;
 	struct legacy_data *data;
 	struct gb_connection *connection;
-	int ret;
+	int i;
+	int ret = -ENOMEM;
+
+	dev_dbg(&bundle->dev,
+			"%s - bundle class = 0x%02x, num_cports = %zu\n",
+			__func__, bundle->class, bundle->num_cports);
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-	data->num_cports = 0;
-	list_for_each_entry(connection, &bundle->connections, bundle_links)
-		data->num_cports++;
+	data->num_cports = bundle->num_cports;
+	data->connections = kcalloc(data->num_cports,
+						sizeof(*data->connections),
+						GFP_KERNEL);
+	if (!data->connections)
+		goto err_free_data;
 
-	dev_dbg(&bundle->dev,
-			"%s - bundle class = 0x%02x, num_cports = %zu\n",
-			__func__, bundle->class, data->num_cports);
+	for (i = 0; i < data->num_cports; ++i) {
+		cport_desc = &bundle->cport_desc[i];
+
+		connection = gb_connection_create_dynamic(bundle->intf,
+						bundle,
+						le16_to_cpu(cport_desc->id),
+						cport_desc->protocol_id);
+		if (!connection)
+			goto err_connections_destroy;
+
+		data->connections[i] = connection;
+	}
 
 	greybus_set_drvdata(bundle, data);
 
-	list_for_each_entry(connection, &bundle->connections, bundle_links) {
+	for (i = 0; i < data->num_cports; ++i) {
+		connection = data->connections[i];
 		dev_dbg(&bundle->dev, "enabling connection %s\n",
 				connection->name);
 
@@ -158,10 +178,13 @@ static int legacy_probe(struct gb_bundle *bundle,
 	return 0;
 
 err_connections_disable:
-	list_for_each_entry_reverse(connection, &bundle->connections,
-							bundle_links) {
-		legacy_connection_exit(connection);
-	}
+	for (--i; i >= 0; --i)
+		legacy_connection_exit(data->connections[i]);
+err_connections_destroy:
+	for (i = 0; i < data->num_cports; ++i)
+		gb_connection_destroy(data->connections[i]);
+	kfree(data->connections);
+err_free_data:
 	kfree(data);
 
 	return ret;
@@ -170,16 +193,17 @@ err_connections_disable:
 static void legacy_disconnect(struct gb_bundle *bundle)
 {
 	struct legacy_data *data = greybus_get_drvdata(bundle);
-	struct gb_connection *connection;
+	int i;
 
 	dev_dbg(&bundle->dev, "%s - bundle class = 0x%02x\n", __func__,
 			bundle->class);
 
-	list_for_each_entry_reverse(connection, &bundle->connections,
-							bundle_links) {
-		legacy_connection_exit(connection);
+	for (i = 0; i < data->num_cports; ++i) {
+		legacy_connection_exit(data->connections[i]);
+		gb_connection_destroy(data->connections[i]);
 	}
 
+	kfree(data->connections);
 	kfree(data);
 }
 

drivers/staging/greybus/manifest.c

@@ -228,19 +228,18 @@ static char *gb_string_get(struct gb_interface *intf, u8 string_id)
  */
 static u32 gb_manifest_parse_cports(struct gb_bundle *bundle)
 {
-	struct gb_connection *connection;
 	struct gb_interface *intf = bundle->intf;
+	struct greybus_descriptor_cport *desc_cport;
 	struct manifest_desc *desc;
 	struct manifest_desc *next;
+	LIST_HEAD(list);
 	u8 bundle_id = bundle->id;
-	u8 protocol_id;
 	u16 cport_id;
 	u32 count = 0;
+	int i;
 
 	/* Set up all cport descriptors associated with this bundle */
 	list_for_each_entry_safe(desc, next, &intf->manifest_descs, links) {
-		struct greybus_descriptor_cport *desc_cport;
-
 		if (desc->type != GREYBUS_TYPE_CPORT)
 			continue;
 
@@ -252,16 +251,26 @@ static u32 gb_manifest_parse_cports(struct gb_bundle *bundle)
 		if (cport_id > CPORT_ID_MAX)
 			goto exit;
 
-		/* Found one.  Set up its function structure */
-		protocol_id = desc_cport->protocol_id;
-
-		connection = gb_connection_create_dynamic(intf, bundle,
-								cport_id,
-								protocol_id);
-		if (!connection)
-			goto exit;
-
+		/* Found one, move it to our temporary list. */
+		list_move(&desc->links, &list);
 		count++;
+	}
+
+	if (!count)
+		return 0;
+
+	bundle->cport_desc = kcalloc(count, sizeof(*bundle->cport_desc),
+					GFP_KERNEL);
+	if (!bundle->cport_desc)
+		goto exit;
+
+	bundle->num_cports = count;
+
+	i = 0;
+	list_for_each_entry_safe(desc, next, &list, links) {
+		desc_cport = desc->data;
+		memcpy(&bundle->cport_desc[i++], desc_cport,
+				sizeof(*desc_cport));
 
 		/* Release the cport descriptor */
 		release_manifest_descriptor(desc);
@@ -269,7 +278,7 @@ static u32 gb_manifest_parse_cports(struct gb_bundle *bundle)
 
 	return count;
 exit:
-
+	release_cport_descriptors(&list, bundle_id);
 	/*
 	 * Free all cports for this bundle to avoid 'excess descriptors'
 	 * warnings.