drivers/staging/greybus/svc.c - kernel/msm-4.9 - Gitiles

 /*
  * SVC Greybus driver.
  *
  * Copyright 2015 Google Inc.
  * Copyright 2015 Linaro Ltd.
  *
  * Released under the GPLv2 only.
  */

 #include <linux/workqueue.h>

 #include "greybus.h"

 #define CPORT_FLAGS_E2EFC       (1)
 #define CPORT_FLAGS_CSD_N       (2)
 #define CPORT_FLAGS_CSV_N       (4)

 enum gb_svc_state {
 	GB_SVC_STATE_RESET,
 	GB_SVC_STATE_PROTOCOL_VERSION,
 	GB_SVC_STATE_SVC_HELLO,
 };

 struct gb_svc {
 	struct gb_connection	*connection;
 	enum gb_svc_state	state;
 };

 struct svc_hotplug {
 	struct work_struct work;
 	struct gb_connection *connection;
 	struct gb_svc_intf_hotplug_request data;
 };

 static struct ida greybus_svc_device_id_map;

 /*
  * AP's SVC cport is required early to get messages from the SVC. This happens
  * even before the Endo is created and hence any modules or interfaces.
  *
  * This is a temporary connection, used only at initial bootup.
  */
 struct gb_connection *
 gb_ap_svc_connection_create(struct greybus_host_device *hd)
 {
 	struct gb_connection *connection;

 	connection = gb_connection_create_range(hd, NULL, hd->parent,
 						GB_SVC_CPORT_ID,
 						GREYBUS_PROTOCOL_SVC,
 						GB_SVC_CPORT_ID,
 						GB_SVC_CPORT_ID + 1);

 	return connection;
 }

 /*
  * We know endo-type and AP's interface id now, lets create a proper svc
  * connection (and its interface/bundle) now and get rid of the initial
  * 'partially' initialized one svc connection.
  */
 static struct gb_interface *
 gb_ap_interface_create(struct greybus_host_device *hd,
 		       struct gb_connection *connection, u8 interface_id)
 {
 	struct gb_interface *intf;
 	struct device *dev = &hd->endo->dev;

 	intf = gb_interface_create(hd, interface_id);
 	if (!intf) {
 		dev_err(dev, "%s: Failed to create interface with id %hhu\n",
 			__func__, interface_id);
 		return NULL;
 	}

 	intf->device_id = GB_DEVICE_ID_AP;
 	svc_update_connection(intf, connection);

 	/* Its no longer a partially initialized connection */
 	hd->initial_svc_connection = NULL;

 	return intf;
 }

 static int gb_svc_intf_device_id(struct gb_svc *svc, u8 intf_id, u8 device_id)
 {
 	struct gb_svc_intf_device_id_request request;

 	request.intf_id = intf_id;
 	request.device_id = device_id;

 	return gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_DEVICE_ID,
 				 &request, sizeof(request), NULL, 0);
 }

 int gb_svc_intf_reset(struct gb_svc *svc, u8 intf_id)
 {
 	struct gb_svc_intf_reset_request request;

 	request.intf_id = intf_id;

 	return gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_RESET,
 				 &request, sizeof(request), NULL, 0);
 }
 EXPORT_SYMBOL_GPL(gb_svc_intf_reset);

 int gb_svc_connection_create(struct gb_svc *svc,
 				u8 intf1_id, u16 cport1_id,
 				u8 intf2_id, u16 cport2_id)
 {
 	struct gb_svc_conn_create_request request;

 	request.intf1_id = intf1_id;
 	request.cport1_id = cport1_id;
 	request.intf2_id = intf2_id;
 	request.cport2_id = cport2_id;
 	/*
 	 * XXX: fix connections paramaters to TC0 and all CPort flags
 	 * for now.
 	 */
 	request.tc = 0;
 	request.flags = CPORT_FLAGS_CSV_N | CPORT_FLAGS_E2EFC;

 	return gb_operation_sync(svc->connection, GB_SVC_TYPE_CONN_CREATE,
 				 &request, sizeof(request), NULL, 0);
 }
 EXPORT_SYMBOL_GPL(gb_svc_connection_create);

 void gb_svc_connection_destroy(struct gb_svc *svc, u8 intf1_id, u16 cport1_id,
 			       u8 intf2_id, u16 cport2_id)
 {
 	struct gb_svc_conn_destroy_request request;
 	struct gb_connection *connection = svc->connection;
 	int ret;

 	request.intf1_id = intf1_id;
 	request.cport1_id = cport1_id;
 	request.intf2_id = intf2_id;
 	request.cport2_id = cport2_id;

 	ret = gb_operation_sync(connection, GB_SVC_TYPE_CONN_DESTROY,
 				&request, sizeof(request), NULL, 0);
 	if (ret) {
 		dev_err(&connection->dev,
 			"failed to destroy connection (%hhx:%hx %hhx:%hx) %d\n",
 			intf1_id, cport1_id, intf2_id, cport2_id, ret);
 	}
 }
 EXPORT_SYMBOL_GPL(gb_svc_connection_destroy);

 static int gb_svc_route_create(struct gb_svc *svc, u8 intf1_id, u8 dev1_id,
 			       u8 intf2_id, u8 dev2_id)
 {
 	struct gb_svc_route_create_request request;

 	request.intf1_id = intf1_id;
 	request.dev1_id = dev1_id;
 	request.intf2_id = intf2_id;
 	request.dev2_id = dev2_id;

 	return gb_operation_sync(svc->connection, GB_SVC_TYPE_ROUTE_CREATE,
 				 &request, sizeof(request), NULL, 0);
 }

 static int gb_svc_version_request(struct gb_operation *op)
 {
 	struct gb_connection *connection = op->connection;
 	struct gb_protocol_version_response *version;
 	struct device *dev = &connection->dev;

 	version = op->request->payload;

 	if (version->major > GB_SVC_VERSION_MAJOR) {
 		dev_err(&connection->dev,
 			"unsupported major version (%hhu > %hhu)\n",
 			version->major, GB_SVC_VERSION_MAJOR);
 		return -ENOTSUPP;
 	}

 	connection->module_major = version->major;
 	connection->module_minor = version->minor;

 	if (!gb_operation_response_alloc(op, sizeof(*version), GFP_KERNEL)) {
 		dev_err(dev, "%s: error allocating response\n",
 				__func__);
 		return -ENOMEM;
 	}

 	version = op->response->payload;
 	version->major = GB_SVC_VERSION_MAJOR;
 	version->minor = GB_SVC_VERSION_MINOR;
 	return 0;
 }

 static int gb_svc_hello(struct gb_operation *op)
 {
 	struct gb_connection *connection = op->connection;
 	struct greybus_host_device *hd = connection->hd;
 	struct gb_svc_hello_request *hello_request;
 	struct device *dev = &connection->dev;
 	struct gb_interface *intf;
 	u16 endo_id;
 	u8 interface_id;
 	int ret;

 	/*
 	 * SVC sends information about the endo and interface-id on the hello
 	 * request, use that to create an endo.
 	 */
 	if (op->request->payload_size < sizeof(*hello_request)) {
 		dev_err(dev, "%s: Illegal size of hello request (%zu < %zu)\n",
 			__func__, op->request->payload_size,
 			sizeof(*hello_request));
 		return -EINVAL;
 	}

 	hello_request = op->request->payload;
 	endo_id = le16_to_cpu(hello_request->endo_id);
 	interface_id = hello_request->interface_id;

 	/* Setup Endo */
 	ret = greybus_endo_setup(hd, endo_id, interface_id);
 	if (ret)
 		return ret;

 	/*
 	 * Endo and its modules are ready now, fix AP's partially initialized
 	 * svc protocol and its connection.
 	 */
 	intf = gb_ap_interface_create(hd, connection, interface_id);
 	if (!intf) {
 		gb_endo_remove(hd->endo);
 		return ret;
 	}

 	return 0;
 }

 /*
  * 'struct svc_hotplug' should be freed by svc_process_hotplug() before it
  * returns, irrespective of success or Failure in bringing up the module.
  */
 static void svc_process_hotplug(struct work_struct *work)
 {
 	struct svc_hotplug *svc_hotplug = container_of(work, struct svc_hotplug,
 						       work);
 	struct gb_svc_intf_hotplug_request *hotplug = &svc_hotplug->data;
 	struct gb_connection *connection = svc_hotplug->connection;
 	struct gb_svc *svc = connection->private;
 	struct greybus_host_device *hd = connection->hd;
 	struct device *dev = &connection->dev;
 	struct gb_interface *intf;
 	u8 intf_id, device_id;
 	int ret;

 	/*
 	 * Grab the information we need.
 	 */
 	intf_id = hotplug->intf_id;

 	intf = gb_interface_create(hd, intf_id);
 	if (!intf) {
 		dev_err(dev, "%s: Failed to create interface with id %hhu\n",
 			__func__, intf_id);
 		goto free_svc_hotplug;
 	}

 	intf->unipro_mfg_id = le32_to_cpu(hotplug->data.unipro_mfg_id);
 	intf->unipro_prod_id = le32_to_cpu(hotplug->data.unipro_prod_id);
 	intf->ara_vend_id = le32_to_cpu(hotplug->data.ara_vend_id);
 	intf->ara_prod_id = le32_to_cpu(hotplug->data.ara_prod_id);

 	/*
 	 * Create a device id for the interface:
 	 * - device id 0 (GB_DEVICE_ID_SVC) belongs to the SVC
 	 * - device id 1 (GB_DEVICE_ID_AP) belongs to the AP
 	 *
 	 * XXX Do we need to allocate device ID for SVC or the AP here? And what
 	 * XXX about an AP with multiple interface blocks?
 	 */
 	device_id = ida_simple_get(&greybus_svc_device_id_map,
 				   GB_DEVICE_ID_MODULES_START, 0, GFP_KERNEL);
 	if (device_id < 0) {
 		ret = device_id;
 		dev_err(dev, "%s: Failed to allocate device id for interface with id %hhu (%d)\n",
 			__func__, intf_id, ret);
 		goto destroy_interface;
 	}

 	ret = gb_svc_intf_device_id(svc, intf_id, device_id);
 	if (ret) {
 		dev_err(dev, "%s: Device id operation failed, interface %hhu device_id %hhu (%d)\n",
 			__func__, intf_id, device_id, ret);
 		goto ida_put;
 	}

 	/*
 	 * Create a two-way route between the AP and the new interface
 	 */
 	ret = gb_svc_route_create(svc, hd->endo->ap_intf_id, GB_DEVICE_ID_AP,
 				  intf_id, device_id);
 	if (ret) {
 		dev_err(dev, "%s: Route create operation failed, interface %hhu device_id %hhu (%d)\n",
 			__func__, intf_id, device_id, ret);
 		goto ida_put;
 	}

 	ret = gb_svc_route_create(svc, intf_id, device_id, hd->endo->ap_intf_id,
 				  GB_DEVICE_ID_AP);
 	if (ret) {
 		dev_err(dev, "%s: Route create operation failed, interface %hhu device_id %hhu (%d)\n",
 			__func__, intf_id, device_id, ret);
 		goto ida_put;
 	}

 	ret = gb_interface_init(intf, device_id);
 	if (ret) {
 		dev_err(dev, "%s: Failed to initialize interface, interface %hhu device_id %hhu (%d)\n",
 			__func__, intf_id, device_id, ret);
 		goto svc_id_free;
 	}

 	goto free_svc_hotplug;

 svc_id_free:
 	/*
 	 * XXX Should we tell SVC that this id doesn't belong to interface
 	 * XXX anymore.
 	 */
 ida_put:
 	ida_simple_remove(&greybus_svc_device_id_map, device_id);
 destroy_interface:
 	gb_interface_remove(hd, intf_id);
 free_svc_hotplug:
 	kfree(svc_hotplug);
 }

 /*
  * Bringing up a module can be time consuming, as that may require lots of
  * initialization on the module side. Over that, we may also need to download
  * the firmware first and flash that on the module.
  *
  * In order to make other hotplug events to not wait for all this to finish,
  * handle most of module hotplug stuff outside of the hotplug callback, with
  * help of a workqueue.
  */
 static int gb_svc_intf_hotplug_recv(struct gb_operation *op)
 {
 	struct gb_message *request = op->request;
 	struct svc_hotplug *svc_hotplug;

 	if (request->payload_size < sizeof(svc_hotplug->data)) {
 		dev_err(&op->connection->dev,
 			"%s: short hotplug request received (%zu < %zu)\n",
 			__func__, request->payload_size,
 			sizeof(svc_hotplug->data));
 		return -EINVAL;
 	}

 	svc_hotplug = kmalloc(sizeof(*svc_hotplug), GFP_KERNEL);
 	if (!svc_hotplug)
 		return -ENOMEM;

 	svc_hotplug->connection = op->connection;
 	memcpy(&svc_hotplug->data, op->request->payload, sizeof(svc_hotplug->data));

 	INIT_WORK(&svc_hotplug->work, svc_process_hotplug);
 	queue_work(system_unbound_wq, &svc_hotplug->work);

 	return 0;
 }

 static int gb_svc_intf_hot_unplug_recv(struct gb_operation *op)
 {
 	struct gb_message *request = op->request;
 	struct gb_svc_intf_hot_unplug_request *hot_unplug = request->payload;
 	struct greybus_host_device *hd = op->connection->hd;
 	struct device *dev = &op->connection->dev;
 	u8 device_id;
 	struct gb_interface *intf;
 	u8 intf_id;

 	if (request->payload_size < sizeof(*hot_unplug)) {
 		dev_err(&op->connection->dev,
 			"short hot unplug request received (%zu < %zu)\n",
 			request->payload_size, sizeof(*hot_unplug));
 		return -EINVAL;
 	}

 	intf_id = hot_unplug->intf_id;

 	intf = gb_interface_find(hd, intf_id);
 	if (!intf) {
 		dev_err(dev, "%s: Couldn't find interface for id %hhu\n",
 			__func__, intf_id);
 		return -EINVAL;
 	}

 	device_id = intf->device_id;
 	gb_interface_remove(hd, intf_id);
 	ida_simple_remove(&greybus_svc_device_id_map, device_id);

 	return 0;
 }

 static int gb_svc_intf_reset_recv(struct gb_operation *op)
 {
 	struct gb_message *request = op->request;
 	struct gb_svc_intf_reset_request *reset;
 	u8 intf_id;

 	if (request->payload_size < sizeof(*reset)) {
 		dev_err(&op->connection->dev,
 			"short reset request received (%zu < %zu)\n",
 			request->payload_size, sizeof(*reset));
 		return -EINVAL;
 	}
 	reset = request->payload;

 	intf_id = reset->intf_id;

 	/* FIXME Reset the interface here */

 	return 0;
 }

 static int gb_svc_request_recv(u8 type, struct gb_operation *op)
 {
 	struct gb_connection *connection = op->connection;
 	struct gb_svc *svc = connection->private;
 	int ret = 0;

 	/*
 	 * SVC requests need to follow a specific order (at least initially) and
 	 * below code takes care of enforcing that. The expected order is:
 	 * - PROTOCOL_VERSION
 	 * - SVC_HELLO
 	 * - Any other request, but the earlier two.
 	 *
 	 * Incoming requests are guaranteed to be serialized and so we don't
 	 * need to protect 'state' for any races.
 	 */
 	switch (type) {
 	case GB_REQUEST_TYPE_PROTOCOL_VERSION:
 		if (svc->state != GB_SVC_STATE_RESET)
 			ret = -EINVAL;
 		break;
 	case GB_SVC_TYPE_SVC_HELLO:
 		if (svc->state != GB_SVC_STATE_PROTOCOL_VERSION)
 			ret = -EINVAL;
 		break;
 	default:
 		if (svc->state != GB_SVC_STATE_SVC_HELLO)
 			ret = -EINVAL;
 		break;
 	}

 	if (ret) {
 		dev_warn(&connection->dev,
 			 "unexpected SVC request 0x%02x received (state %u)\n",
 			 type, svc->state);
 		return ret;
 	}

 	switch (type) {
 	case GB_REQUEST_TYPE_PROTOCOL_VERSION:
 		ret = gb_svc_version_request(op);
 		if (!ret)
 			svc->state = GB_SVC_STATE_PROTOCOL_VERSION;
 		return ret;
 	case GB_SVC_TYPE_SVC_HELLO:
 		ret = gb_svc_hello(op);
 		if (!ret)
 			svc->state = GB_SVC_STATE_SVC_HELLO;
 		return ret;
 	case GB_SVC_TYPE_INTF_HOTPLUG:
 		return gb_svc_intf_hotplug_recv(op);
 	case GB_SVC_TYPE_INTF_HOT_UNPLUG:
 		return gb_svc_intf_hot_unplug_recv(op);
 	case GB_SVC_TYPE_INTF_RESET:
 		return gb_svc_intf_reset_recv(op);
 	default:
 		dev_err(&op->connection->dev,
 			"unsupported request: %hhu\n", type);
 		return -EINVAL;
 	}
 }

 static int gb_svc_connection_init(struct gb_connection *connection)
 {
 	struct gb_svc *svc;

 	svc = kzalloc(sizeof(*svc), GFP_KERNEL);
 	if (!svc)
 		return -ENOMEM;

 	connection->hd->svc = svc;
 	svc->state = GB_SVC_STATE_RESET;
 	svc->connection = connection;
 	connection->private = svc;

 	WARN_ON(connection->hd->initial_svc_connection);
 	connection->hd->initial_svc_connection = connection;

 	ida_init(&greybus_svc_device_id_map);

 	return 0;
 }

 static void gb_svc_connection_exit(struct gb_connection *connection)
 {
 	struct gb_svc *svc = connection->private;

 	connection->hd->svc = NULL;
 	connection->private = NULL;
 	kfree(svc);
 }

 static struct gb_protocol svc_protocol = {
 	.name			= "svc",
 	.id			= GREYBUS_PROTOCOL_SVC,
 	.major			= GB_SVC_VERSION_MAJOR,
 	.minor			= GB_SVC_VERSION_MINOR,
 	.connection_init	= gb_svc_connection_init,
 	.connection_exit	= gb_svc_connection_exit,
 	.request_recv		= gb_svc_request_recv,
 	.flags			= GB_PROTOCOL_SKIP_CONTROL_CONNECTED |
 				  GB_PROTOCOL_SKIP_CONTROL_DISCONNECTED |
 				  GB_PROTOCOL_NO_BUNDLE |
 				  GB_PROTOCOL_SKIP_VERSION |
 				  GB_PROTOCOL_SKIP_SVC_CONNECTION,
 };
 gb_builtin_protocol_driver(svc_protocol);
	/*
	* SVC Greybus driver.
	*
	* Copyright 2015 Google Inc.
	* Copyright 2015 Linaro Ltd.
	*
	* Released under the GPLv2 only.
	*/

	#include <linux/workqueue.h>

	#include "greybus.h"

	#define CPORT_FLAGS_E2EFC (1)
	#define CPORT_FLAGS_CSD_N (2)
	#define CPORT_FLAGS_CSV_N (4)

	enum gb_svc_state {
	GB_SVC_STATE_RESET,
	GB_SVC_STATE_PROTOCOL_VERSION,
	GB_SVC_STATE_SVC_HELLO,
	};

	struct gb_svc {
	struct gb_connection *connection;
	enum gb_svc_state state;
	};

	struct svc_hotplug {
	struct work_struct work;
	struct gb_connection *connection;
	struct gb_svc_intf_hotplug_request data;
	};

	static struct ida greybus_svc_device_id_map;

	/*
	* AP's SVC cport is required early to get messages from the SVC. This happens
	* even before the Endo is created and hence any modules or interfaces.
	*
	* This is a temporary connection, used only at initial bootup.
	*/
	struct gb_connection *
	gb_ap_svc_connection_create(struct greybus_host_device *hd)
	{
	struct gb_connection *connection;

	connection = gb_connection_create_range(hd, NULL, hd->parent,
	GB_SVC_CPORT_ID,
	GREYBUS_PROTOCOL_SVC,
	GB_SVC_CPORT_ID,
	GB_SVC_CPORT_ID + 1);

	return connection;
	}

	/*
	* We know endo-type and AP's interface id now, lets create a proper svc
	* connection (and its interface/bundle) now and get rid of the initial
	* 'partially' initialized one svc connection.
	*/
	static struct gb_interface *
	gb_ap_interface_create(struct greybus_host_device *hd,
	struct gb_connection *connection, u8 interface_id)
	{
	struct gb_interface *intf;
	struct device *dev = &hd->endo->dev;

	intf = gb_interface_create(hd, interface_id);
	if (!intf) {
	dev_err(dev, "%s: Failed to create interface with id %hhu\n",
	__func__, interface_id);
	return NULL;
	}

	intf->device_id = GB_DEVICE_ID_AP;
	svc_update_connection(intf, connection);

	/* Its no longer a partially initialized connection */
	hd->initial_svc_connection = NULL;

	return intf;
	}

	static int gb_svc_intf_device_id(struct gb_svc *svc, u8 intf_id, u8 device_id)
	{
	struct gb_svc_intf_device_id_request request;

	request.intf_id = intf_id;
	request.device_id = device_id;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_DEVICE_ID,
	&request, sizeof(request), NULL, 0);
	}

	int gb_svc_intf_reset(struct gb_svc *svc, u8 intf_id)
	{
	struct gb_svc_intf_reset_request request;

	request.intf_id = intf_id;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_RESET,
	&request, sizeof(request), NULL, 0);
	}
	EXPORT_SYMBOL_GPL(gb_svc_intf_reset);

	int gb_svc_connection_create(struct gb_svc *svc,
	u8 intf1_id, u16 cport1_id,
	u8 intf2_id, u16 cport2_id)
	{
	struct gb_svc_conn_create_request request;

	request.intf1_id = intf1_id;
	request.cport1_id = cport1_id;
	request.intf2_id = intf2_id;
	request.cport2_id = cport2_id;
	/*
	* XXX: fix connections paramaters to TC0 and all CPort flags
	* for now.
	*/
	request.tc = 0;
	request.flags = CPORT_FLAGS_CSV_N \| CPORT_FLAGS_E2EFC;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_CONN_CREATE,
	&request, sizeof(request), NULL, 0);
	}
	EXPORT_SYMBOL_GPL(gb_svc_connection_create);

	void gb_svc_connection_destroy(struct gb_svc *svc, u8 intf1_id, u16 cport1_id,
	u8 intf2_id, u16 cport2_id)
	{
	struct gb_svc_conn_destroy_request request;
	struct gb_connection *connection = svc->connection;
	int ret;

	request.intf1_id = intf1_id;
	request.cport1_id = cport1_id;
	request.intf2_id = intf2_id;
	request.cport2_id = cport2_id;

	ret = gb_operation_sync(connection, GB_SVC_TYPE_CONN_DESTROY,
	&request, sizeof(request), NULL, 0);
	if (ret) {
	dev_err(&connection->dev,
	"failed to destroy connection (%hhx:%hx %hhx:%hx) %d\n",
	intf1_id, cport1_id, intf2_id, cport2_id, ret);
	}
	}
	EXPORT_SYMBOL_GPL(gb_svc_connection_destroy);

	static int gb_svc_route_create(struct gb_svc *svc, u8 intf1_id, u8 dev1_id,
	u8 intf2_id, u8 dev2_id)
	{
	struct gb_svc_route_create_request request;

	request.intf1_id = intf1_id;
	request.dev1_id = dev1_id;
	request.intf2_id = intf2_id;
	request.dev2_id = dev2_id;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_ROUTE_CREATE,
	&request, sizeof(request), NULL, 0);
	}

	static int gb_svc_version_request(struct gb_operation *op)
	{
	struct gb_connection *connection = op->connection;
	struct gb_protocol_version_response *version;
	struct device *dev = &connection->dev;

	version = op->request->payload;

	if (version->major > GB_SVC_VERSION_MAJOR) {
	dev_err(&connection->dev,
	"unsupported major version (%hhu > %hhu)\n",
	version->major, GB_SVC_VERSION_MAJOR);
	return -ENOTSUPP;
	}

	connection->module_major = version->major;
	connection->module_minor = version->minor;

	if (!gb_operation_response_alloc(op, sizeof(*version), GFP_KERNEL)) {
	dev_err(dev, "%s: error allocating response\n",
	__func__);
	return -ENOMEM;
	}

	version = op->response->payload;
	version->major = GB_SVC_VERSION_MAJOR;
	version->minor = GB_SVC_VERSION_MINOR;
	return 0;
	}

	static int gb_svc_hello(struct gb_operation *op)
	{
	struct gb_connection *connection = op->connection;
	struct greybus_host_device *hd = connection->hd;
	struct gb_svc_hello_request *hello_request;
	struct device *dev = &connection->dev;
	struct gb_interface *intf;
	u16 endo_id;
	u8 interface_id;
	int ret;

	/*
	* SVC sends information about the endo and interface-id on the hello
	* request, use that to create an endo.
	*/
	if (op->request->payload_size < sizeof(*hello_request)) {
	dev_err(dev, "%s: Illegal size of hello request (%zu < %zu)\n",
	__func__, op->request->payload_size,
	sizeof(*hello_request));
	return -EINVAL;
	}

	hello_request = op->request->payload;
	endo_id = le16_to_cpu(hello_request->endo_id);
	interface_id = hello_request->interface_id;

	/* Setup Endo */
	ret = greybus_endo_setup(hd, endo_id, interface_id);
	if (ret)
	return ret;

	/*
	* Endo and its modules are ready now, fix AP's partially initialized
	* svc protocol and its connection.
	*/
	intf = gb_ap_interface_create(hd, connection, interface_id);
	if (!intf) {
	gb_endo_remove(hd->endo);
	return ret;
	}

	return 0;
	}

	/*
	* 'struct svc_hotplug' should be freed by svc_process_hotplug() before it
	* returns, irrespective of success or Failure in bringing up the module.
	*/
	static void svc_process_hotplug(struct work_struct *work)
	{
	struct svc_hotplug *svc_hotplug = container_of(work, struct svc_hotplug,
	work);
	struct gb_svc_intf_hotplug_request *hotplug = &svc_hotplug->data;
	struct gb_connection *connection = svc_hotplug->connection;
	struct gb_svc *svc = connection->private;
	struct greybus_host_device *hd = connection->hd;
	struct device *dev = &connection->dev;
	struct gb_interface *intf;
	u8 intf_id, device_id;
	int ret;

	/*
	* Grab the information we need.
	*/
	intf_id = hotplug->intf_id;

	intf = gb_interface_create(hd, intf_id);
	if (!intf) {
	dev_err(dev, "%s: Failed to create interface with id %hhu\n",
	__func__, intf_id);
	goto free_svc_hotplug;
	}

	intf->unipro_mfg_id = le32_to_cpu(hotplug->data.unipro_mfg_id);
	intf->unipro_prod_id = le32_to_cpu(hotplug->data.unipro_prod_id);
	intf->ara_vend_id = le32_to_cpu(hotplug->data.ara_vend_id);
	intf->ara_prod_id = le32_to_cpu(hotplug->data.ara_prod_id);

	/*
	* Create a device id for the interface:
	* - device id 0 (GB_DEVICE_ID_SVC) belongs to the SVC
	* - device id 1 (GB_DEVICE_ID_AP) belongs to the AP
	*
	* XXX Do we need to allocate device ID for SVC or the AP here? And what
	* XXX about an AP with multiple interface blocks?
	*/
	device_id = ida_simple_get(&greybus_svc_device_id_map,
	GB_DEVICE_ID_MODULES_START, 0, GFP_KERNEL);
	if (device_id < 0) {
	ret = device_id;
	dev_err(dev, "%s: Failed to allocate device id for interface with id %hhu (%d)\n",
	__func__, intf_id, ret);
	goto destroy_interface;
	}

	ret = gb_svc_intf_device_id(svc, intf_id, device_id);
	if (ret) {
	dev_err(dev, "%s: Device id operation failed, interface %hhu device_id %hhu (%d)\n",
	__func__, intf_id, device_id, ret);
	goto ida_put;
	}

	/*
	* Create a two-way route between the AP and the new interface
	*/
	ret = gb_svc_route_create(svc, hd->endo->ap_intf_id, GB_DEVICE_ID_AP,
	intf_id, device_id);
	if (ret) {
	dev_err(dev, "%s: Route create operation failed, interface %hhu device_id %hhu (%d)\n",
	__func__, intf_id, device_id, ret);
	goto ida_put;
	}

	ret = gb_svc_route_create(svc, intf_id, device_id, hd->endo->ap_intf_id,
	GB_DEVICE_ID_AP);
	if (ret) {
	dev_err(dev, "%s: Route create operation failed, interface %hhu device_id %hhu (%d)\n",
	__func__, intf_id, device_id, ret);
	goto ida_put;
	}

	ret = gb_interface_init(intf, device_id);
	if (ret) {
	dev_err(dev, "%s: Failed to initialize interface, interface %hhu device_id %hhu (%d)\n",
	__func__, intf_id, device_id, ret);
	goto svc_id_free;
	}

	goto free_svc_hotplug;

	svc_id_free:
	/*
	* XXX Should we tell SVC that this id doesn't belong to interface
	* XXX anymore.
	*/
	ida_put:
	ida_simple_remove(&greybus_svc_device_id_map, device_id);
	destroy_interface:
	gb_interface_remove(hd, intf_id);
	free_svc_hotplug:
	kfree(svc_hotplug);
	}

	/*
	* Bringing up a module can be time consuming, as that may require lots of
	* initialization on the module side. Over that, we may also need to download
	* the firmware first and flash that on the module.
	*
	* In order to make other hotplug events to not wait for all this to finish,
	* handle most of module hotplug stuff outside of the hotplug callback, with
	* help of a workqueue.
	*/
	static int gb_svc_intf_hotplug_recv(struct gb_operation *op)
	{
	struct gb_message *request = op->request;
	struct svc_hotplug *svc_hotplug;

	if (request->payload_size < sizeof(svc_hotplug->data)) {
	dev_err(&op->connection->dev,
	"%s: short hotplug request received (%zu < %zu)\n",
	__func__, request->payload_size,
	sizeof(svc_hotplug->data));
	return -EINVAL;
	}

	svc_hotplug = kmalloc(sizeof(*svc_hotplug), GFP_KERNEL);
	if (!svc_hotplug)
	return -ENOMEM;

	svc_hotplug->connection = op->connection;
	memcpy(&svc_hotplug->data, op->request->payload, sizeof(svc_hotplug->data));

	INIT_WORK(&svc_hotplug->work, svc_process_hotplug);
	queue_work(system_unbound_wq, &svc_hotplug->work);

	return 0;
	}

	static int gb_svc_intf_hot_unplug_recv(struct gb_operation *op)
	{
	struct gb_message *request = op->request;
	struct gb_svc_intf_hot_unplug_request *hot_unplug = request->payload;
	struct greybus_host_device *hd = op->connection->hd;
	struct device *dev = &op->connection->dev;
	u8 device_id;
	struct gb_interface *intf;
	u8 intf_id;

	if (request->payload_size < sizeof(*hot_unplug)) {
	dev_err(&op->connection->dev,
	"short hot unplug request received (%zu < %zu)\n",
	request->payload_size, sizeof(*hot_unplug));
	return -EINVAL;
	}

	intf_id = hot_unplug->intf_id;

	intf = gb_interface_find(hd, intf_id);
	if (!intf) {
	dev_err(dev, "%s: Couldn't find interface for id %hhu\n",
	__func__, intf_id);
	return -EINVAL;
	}

	device_id = intf->device_id;
	gb_interface_remove(hd, intf_id);
	ida_simple_remove(&greybus_svc_device_id_map, device_id);

	return 0;
	}

	static int gb_svc_intf_reset_recv(struct gb_operation *op)
	{
	struct gb_message *request = op->request;
	struct gb_svc_intf_reset_request *reset;
	u8 intf_id;

	if (request->payload_size < sizeof(*reset)) {
	dev_err(&op->connection->dev,
	"short reset request received (%zu < %zu)\n",
	request->payload_size, sizeof(*reset));
	return -EINVAL;
	}
	reset = request->payload;

	intf_id = reset->intf_id;

	/* FIXME Reset the interface here */

	return 0;
	}

	static int gb_svc_request_recv(u8 type, struct gb_operation *op)
	{
	struct gb_connection *connection = op->connection;
	struct gb_svc *svc = connection->private;
	int ret = 0;

	/*
	* SVC requests need to follow a specific order (at least initially) and
	* below code takes care of enforcing that. The expected order is:
	* - PROTOCOL_VERSION
	* - SVC_HELLO
	* - Any other request, but the earlier two.
	*
	* Incoming requests are guaranteed to be serialized and so we don't
	* need to protect 'state' for any races.
	*/
	switch (type) {
	case GB_REQUEST_TYPE_PROTOCOL_VERSION:
	if (svc->state != GB_SVC_STATE_RESET)
	ret = -EINVAL;
	break;
	case GB_SVC_TYPE_SVC_HELLO:
	if (svc->state != GB_SVC_STATE_PROTOCOL_VERSION)
	ret = -EINVAL;
	break;
	default:
	if (svc->state != GB_SVC_STATE_SVC_HELLO)
	ret = -EINVAL;
	break;
	}

	if (ret) {
	dev_warn(&connection->dev,
	"unexpected SVC request 0x%02x received (state %u)\n",
	type, svc->state);
	return ret;
	}

	switch (type) {
	case GB_REQUEST_TYPE_PROTOCOL_VERSION:
	ret = gb_svc_version_request(op);
	if (!ret)
	svc->state = GB_SVC_STATE_PROTOCOL_VERSION;
	return ret;
	case GB_SVC_TYPE_SVC_HELLO:
	ret = gb_svc_hello(op);
	if (!ret)
	svc->state = GB_SVC_STATE_SVC_HELLO;
	return ret;
	case GB_SVC_TYPE_INTF_HOTPLUG:
	return gb_svc_intf_hotplug_recv(op);
	case GB_SVC_TYPE_INTF_HOT_UNPLUG:
	return gb_svc_intf_hot_unplug_recv(op);
	case GB_SVC_TYPE_INTF_RESET:
	return gb_svc_intf_reset_recv(op);
	default:
	dev_err(&op->connection->dev,
	"unsupported request: %hhu\n", type);
	return -EINVAL;
	}
	}

	static int gb_svc_connection_init(struct gb_connection *connection)
	{
	struct gb_svc *svc;

	svc = kzalloc(sizeof(*svc), GFP_KERNEL);
	if (!svc)
	return -ENOMEM;

	connection->hd->svc = svc;
	svc->state = GB_SVC_STATE_RESET;
	svc->connection = connection;
	connection->private = svc;

	WARN_ON(connection->hd->initial_svc_connection);
	connection->hd->initial_svc_connection = connection;

	ida_init(&greybus_svc_device_id_map);

	return 0;
	}

	static void gb_svc_connection_exit(struct gb_connection *connection)
	{
	struct gb_svc *svc = connection->private;

	connection->hd->svc = NULL;
	connection->private = NULL;
	kfree(svc);
	}

	static struct gb_protocol svc_protocol = {
	.name = "svc",
	.id = GREYBUS_PROTOCOL_SVC,
	.major = GB_SVC_VERSION_MAJOR,
	.minor = GB_SVC_VERSION_MINOR,
	.connection_init = gb_svc_connection_init,
	.connection_exit = gb_svc_connection_exit,
	.request_recv = gb_svc_request_recv,
	.flags = GB_PROTOCOL_SKIP_CONTROL_CONNECTED \|
	GB_PROTOCOL_SKIP_CONTROL_DISCONNECTED \|
	GB_PROTOCOL_NO_BUNDLE \|
	GB_PROTOCOL_SKIP_VERSION \|
	GB_PROTOCOL_SKIP_SVC_CONNECTION,
	};
	gb_builtin_protocol_driver(svc_protocol);