thunderbolt: Add support for XDomain discovery protocol

When two hosts are connected over a Thunderbolt cable, there is a
protocol they can use to communicate capabilities supported by the host.
The discovery protocol uses automatically configured control channel
(ring 0) and is build on top of request/response transactions using
special XDomain primitives provided by the Thunderbolt base protocol.

The capabilities consists of a root directory block of basic properties
used for identification of the host, and then there can be zero or more
directories each describing a Thunderbolt service and its capabilities.

Once both sides have discovered what is supported the two hosts can
setup high-speed DMA paths and transfer data to the other side using
whatever protocol was agreed based on the properties. The software
protocol used to communicate which DMA paths to enable is service
specific.

This patch adds support for the XDomain discovery protocol to the
Thunderbolt bus. We model each remote host connection as a Linux XDomain
device. For each Thunderbolt service found supported on the XDomain
device, we create Linux Thunderbolt service device which Thunderbolt
service drivers can then bind to based on the protocol identification
information retrieved from the property directory describing the
service.

This code is based on the work done by Amir Levy and Michael Jamet.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 2159 insertions, 18 deletions

diff --git a/drivers/thunderbolt/Makefile b/drivers/thunderbolt/Makefile
index 7afd21f5383a..f2f0de27252b 100644
--- a/drivers/thunderbolt/Makefile
+++ b/drivers/thunderbolt/Makefile
@@ -1,3 +1,3 @@
 obj-${CONFIG_THUNDERBOLT} := thunderbolt.o
 thunderbolt-objs := nhi.o ctl.o tb.o switch.o cap.o path.o tunnel_pci.o eeprom.o
-thunderbolt-objs += domain.o dma_port.o icm.o property.o
+thunderbolt-objs += domain.o dma_port.o icm.o property.o xdomain.o
diff --git a/drivers/thunderbolt/ctl.c b/drivers/thunderbolt/ctl.c
index e6a4c9458c76..46e393c5fd1d 100644
--- a/drivers/thunderbolt/ctl.c
+++ b/drivers/thunderbolt/ctl.c
@@ -368,10 +368,10 @@ static int tb_ctl_tx(struct tb_ctl *ctl, const void *data, size_t len,
 /**
  * tb_ctl_handle_event() - acknowledge a plug event, invoke ctl->callback
  */
-static void tb_ctl_handle_event(struct tb_ctl *ctl, enum tb_cfg_pkg_type type,
+static bool tb_ctl_handle_event(struct tb_ctl *ctl, enum tb_cfg_pkg_type type,
 				struct ctl_pkg *pkg, size_t size)
 {
-	ctl->callback(ctl->callback_data, type, pkg->buffer, size);
+	return ctl->callback(ctl->callback_data, type, pkg->buffer, size);
 }
 
 static void tb_ctl_rx_submit(struct ctl_pkg *pkg)
@@ -444,6 +444,8 @@ static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
 		break;
 
 	case TB_CFG_PKG_EVENT:
+	case TB_CFG_PKG_XDOMAIN_RESP:
+	case TB_CFG_PKG_XDOMAIN_REQ:
 		if (*(__be32 *)(pkg->buffer + frame->size) != crc32) {
 			tb_ctl_err(pkg->ctl,
 				   "RX: checksum mismatch, dropping packet\n");
@@ -451,8 +453,9 @@ static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
 		}
 		/* Fall through */
 	case TB_CFG_PKG_ICM_EVENT:
-		tb_ctl_handle_event(pkg->ctl, frame->eof, pkg, frame->size);
-		goto rx;
+		if (tb_ctl_handle_event(pkg->ctl, frame->eof, pkg, frame->size))
+			goto rx;
+		break;
 
 	default:
 		break;
diff --git a/drivers/thunderbolt/ctl.h b/drivers/thunderbolt/ctl.h
index d0f21e1e0b8b..85c49dd301ea 100644
--- a/drivers/thunderbolt/ctl.h
+++ b/drivers/thunderbolt/ctl.h
@@ -16,7 +16,7 @@
 /* control channel */
 struct tb_ctl;
 
-typedef void (*event_cb)(void *data, enum tb_cfg_pkg_type type,
+typedef bool (*event_cb)(void *data, enum tb_cfg_pkg_type type,
 			 const void *buf, size_t size);
 
 struct tb_ctl *tb_ctl_alloc(struct tb_nhi *nhi, event_cb cb, void *cb_data);
diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c
index 9f2dcd48974d..9b90115319ce 100644
--- a/drivers/thunderbolt/domain.c
+++ b/drivers/thunderbolt/domain.c
@@ -20,6 +20,98 @@
 
 static DEFINE_IDA(tb_domain_ida);
 
+static bool match_service_id(const struct tb_service_id *id,
+			     const struct tb_service *svc)
+{
+	if (id->match_flags & TBSVC_MATCH_PROTOCOL_KEY) {
+		if (strcmp(id->protocol_key, svc->key))
+			return false;
+	}
+
+	if (id->match_flags & TBSVC_MATCH_PROTOCOL_ID) {
+		if (id->protocol_id != svc->prtcid)
+			return false;
+	}
+
+	if (id->match_flags & TBSVC_MATCH_PROTOCOL_VERSION) {
+		if (id->protocol_version != svc->prtcvers)
+			return false;
+	}
+
+	if (id->match_flags & TBSVC_MATCH_PROTOCOL_VERSION) {
+		if (id->protocol_revision != svc->prtcrevs)
+			return false;
+	}
+
+	return true;
+}
+
+static const struct tb_service_id *__tb_service_match(struct device *dev,
+						      struct device_driver *drv)
+{
+	struct tb_service_driver *driver;
+	const struct tb_service_id *ids;
+	struct tb_service *svc;
+
+	svc = tb_to_service(dev);
+	if (!svc)
+		return NULL;
+
+	driver = container_of(drv, struct tb_service_driver, driver);
+	if (!driver->id_table)
+		return NULL;
+
+	for (ids = driver->id_table; ids->match_flags != 0; ids++) {
+		if (match_service_id(ids, svc))
+			return ids;
+	}
+
+	return NULL;
+}
+
+static int tb_service_match(struct device *dev, struct device_driver *drv)
+{
+	return !!__tb_service_match(dev, drv);
+}
+
+static int tb_service_probe(struct device *dev)
+{
+	struct tb_service *svc = tb_to_service(dev);
+	struct tb_service_driver *driver;
+	const struct tb_service_id *id;
+
+	driver = container_of(dev->driver, struct tb_service_driver, driver);
+	id = __tb_service_match(dev, &driver->driver);
+
+	return driver->probe(svc, id);
+}
+
+static int tb_service_remove(struct device *dev)
+{
+	struct tb_service *svc = tb_to_service(dev);
+	struct tb_service_driver *driver;
+
+	driver = container_of(dev->driver, struct tb_service_driver, driver);
+	if (driver->remove)
+		driver->remove(svc);
+
+	return 0;
+}
+
+static void tb_service_shutdown(struct device *dev)
+{
+	struct tb_service_driver *driver;
+	struct tb_service *svc;
+
+	svc = tb_to_service(dev);
+	if (!svc || !dev->driver)
+		return;
+
+	driver = container_of(dev->driver, struct tb_service_driver, driver);
+	if (driver->shutdown)
+		driver->shutdown(svc);
+}
+
 static const char * const tb_security_names[] = {
 	[TB_SECURITY_NONE] = "none",
 	[TB_SECURITY_USER] = "user",
@@ -52,6 +144,10 @@ static const struct attribute_group *domain_attr_groups[] = {
 
 struct bus_type tb_bus_type = {
 	.name = "thunderbolt",
+	.match = tb_service_match,
+	.probe = tb_service_probe,
+	.remove = tb_service_remove,
+	.shutdown = tb_service_shutdown,
 };
 
 static void tb_domain_release(struct device *dev)
@@ -128,17 +224,26 @@ err_free:
 	return NULL;
 }
 
-static void tb_domain_event_cb(void *data, enum tb_cfg_pkg_type type,
+static bool tb_domain_event_cb(void *data, enum tb_cfg_pkg_type type,
 			       const void *buf, size_t size)
 {
 	struct tb *tb = data;
 
 	if (!tb->cm_ops->handle_event) {
 		tb_warn(tb, "domain does not have event handler\n");
-		return;
+		return true;
 	}
 
-	tb->cm_ops->handle_event(tb, type, buf, size);
+	switch (type) {
+	case TB_CFG_PKG_XDOMAIN_REQ:
+	case TB_CFG_PKG_XDOMAIN_RESP:
+		return tb_xdomain_handle_request(tb, type, buf, size);
+
+	default:
+		tb->cm_ops->handle_event(tb, type, buf, size);
+	}
+
+	return true;
 }
 
 /**
@@ -443,9 +548,92 @@ int tb_domain_disconnect_pcie_paths(struct tb *tb)
 	return tb->cm_ops->disconnect_pcie_paths(tb);
 }
 
+/**
+ * tb_domain_approve_xdomain_paths() - Enable DMA paths for XDomain
+ * @tb: Domain enabling the DMA paths
+ * @xd: XDomain DMA paths are created to
+ *
+ * Calls connection manager specific method to enable DMA paths to the
+ * XDomain in question.
+ *
+ * Return: 0% in case of success and negative errno otherwise. In
+ * particular returns %-ENOTSUPP if the connection manager
+ * implementation does not support XDomains.
+ */
+int tb_domain_approve_xdomain_paths(struct tb *tb, struct tb_xdomain *xd)
+{
+	if (!tb->cm_ops->approve_xdomain_paths)
+		return -ENOTSUPP;
+
+	return tb->cm_ops->approve_xdomain_paths(tb, xd);
+}
+
+/**
+ * tb_domain_disconnect_xdomain_paths() - Disable DMA paths for XDomain
+ * @tb: Domain disabling the DMA paths
+ * @xd: XDomain whose DMA paths are disconnected
+ *
+ * Calls connection manager specific method to disconnect DMA paths to
+ * the XDomain in question.
+ *
+ * Return: 0% in case of success and negative errno otherwise. In
+ * particular returns %-ENOTSUPP if the connection manager
+ * implementation does not support XDomains.
+ */
+int tb_domain_disconnect_xdomain_paths(struct tb *tb, struct tb_xdomain *xd)
+{
+	if (!tb->cm_ops->disconnect_xdomain_paths)
+		return -ENOTSUPP;
+
+	return tb->cm_ops->disconnect_xdomain_paths(tb, xd);
+}
+
+static int disconnect_xdomain(struct device *dev, void *data)
+{
+	struct tb_xdomain *xd;
+	struct tb *tb = data;
+	int ret = 0;
+
+	xd = tb_to_xdomain(dev);
+	if (xd && xd->tb == tb)
+		ret = tb_xdomain_disable_paths(xd);
+
+	return ret;
+}
+
+/**
+ * tb_domain_disconnect_all_paths() - Disconnect all paths for the domain
+ * @tb: Domain whose paths are disconnected
+ *
+ * This function can be used to disconnect all paths (PCIe, XDomain) for
+ * example in preparation for host NVM firmware upgrade. After this is
+ * called the paths cannot be established without resetting the switch.
+ *
+ * Return: %0 in case of success and negative errno otherwise.
+ */
+int tb_domain_disconnect_all_paths(struct tb *tb)
+{
+	int ret;
+
+	ret = tb_domain_disconnect_pcie_paths(tb);
+	if (ret)
+		return ret;
+
+	return bus_for_each_dev(&tb_bus_type, NULL, tb, disconnect_xdomain);
+}
+
 int tb_domain_init(void)
 {
-	return bus_register(&tb_bus_type);
+	int ret;
+
+	ret = tb_xdomain_init();
+	if (ret)
+		return ret;
+	ret = bus_register(&tb_bus_type);
+	if (ret)
+		tb_xdomain_exit();
+
+	return ret;
 }
 
 void tb_domain_exit(void)
@@ -453,4 +641,5 @@ void tb_domain_exit(void)
 	bus_unregister(&tb_bus_type);
 	ida_destroy(&tb_domain_ida);
 	tb_switch_exit();
+	tb_xdomain_exit();
 }
diff --git a/drivers/thunderbolt/icm.c b/drivers/thunderbolt/icm.c
index 8c22b91ed040..ab02d13f40b7 100644
--- a/drivers/thunderbolt/icm.c
+++ b/drivers/thunderbolt/icm.c
@@ -60,6 +60,8 @@
  * @get_route: Find a route string for given switch
  * @device_connected: Handle device connected ICM message
  * @device_disconnected: Handle device disconnected ICM message
+ * @xdomain_connected - Handle XDomain connected ICM message
+ * @xdomain_disconnected - Handle XDomain disconnected ICM message
  */
 struct icm {
 	struct mutex request_lock;
@@ -74,6 +76,10 @@ struct icm {
 				 const struct icm_pkg_header *hdr);
 	void (*device_disconnected)(struct tb *tb,
 				    const struct icm_pkg_header *hdr);
+	void (*xdomain_connected)(struct tb *tb,
+				  const struct icm_pkg_header *hdr);
+	void (*xdomain_disconnected)(struct tb *tb,
+				     const struct icm_pkg_header *hdr);
 };
 
 struct icm_notification {
@@ -89,7 +95,10 @@ static inline struct tb *icm_to_tb(struct icm *icm)
 
 static inline u8 phy_port_from_route(u64 route, u8 depth)
 {
-	return tb_phy_port_from_link(route >> ((depth - 1) * 8));
+	u8 link;
+
+	link = depth ? route >> ((depth - 1) * 8) : route;
+	return tb_phy_port_from_link(link);
 }
 
 static inline u8 dual_link_from_link(u8 link)
@@ -320,6 +329,51 @@ static int icm_fr_challenge_switch_key(struct tb *tb, struct tb_switch *sw,
 	return 0;
 }
 
+static int icm_fr_approve_xdomain_paths(struct tb *tb, struct tb_xdomain *xd)
+{
+	struct icm_fr_pkg_approve_xdomain_response reply;
+	struct icm_fr_pkg_approve_xdomain request;
+	int ret;
+
+	memset(&request, 0, sizeof(request));
+	request.hdr.code = ICM_APPROVE_XDOMAIN;
+	request.link_info = xd->depth << ICM_LINK_INFO_DEPTH_SHIFT | xd->link;
+	memcpy(&request.remote_uuid, xd->remote_uuid, sizeof(*xd->remote_uuid));
+
+	request.transmit_path = xd->transmit_path;
+	request.transmit_ring = xd->transmit_ring;
+	request.receive_path = xd->receive_path;
+	request.receive_ring = xd->receive_ring;
+
+	memset(&reply, 0, sizeof(reply));
+	ret = icm_request(tb, &request, sizeof(request), &reply, sizeof(reply),
+			  1, ICM_TIMEOUT);
+	if (ret)
+		return ret;
+
+	if (reply.hdr.flags & ICM_FLAGS_ERROR)
+		return -EIO;
+
+	return 0;
+}
+
+static int icm_fr_disconnect_xdomain_paths(struct tb *tb, struct tb_xdomain *xd)
+{
+	u8 phy_port;
+	u8 cmd;
+
+	phy_port = tb_phy_port_from_link(xd->link);
+	if (phy_port == 0)
+		cmd = NHI_MAILBOX_DISCONNECT_PA;
+	else
+		cmd = NHI_MAILBOX_DISCONNECT_PB;
+
+	nhi_mailbox_cmd(tb->nhi, cmd, 1);
+	usleep_range(10, 50);
+	nhi_mailbox_cmd(tb->nhi, cmd, 2);
+	return 0;
+}
+
 static void remove_switch(struct tb_switch *sw)
 {
 	struct tb_switch *parent_sw;
@@ -475,6 +529,141 @@ icm_fr_device_disconnected(struct tb *tb, const struct icm_pkg_header *hdr)
 	tb_switch_put(sw);
 }
 
+static void remove_xdomain(struct tb_xdomain *xd)
+{
+	struct tb_switch *sw;
+
+	sw = tb_to_switch(xd->dev.parent);
+	tb_port_at(xd->route, sw)->xdomain = NULL;
+	tb_xdomain_remove(xd);
+}
+
+static void
+icm_fr_xdomain_connected(struct tb *tb, const struct icm_pkg_header *hdr)
+{
+	const struct icm_fr_event_xdomain_connected *pkg =
+		(const struct icm_fr_event_xdomain_connected *)hdr;
+	struct tb_xdomain *xd;
+	struct tb_switch *sw;
+	u8 link, depth;
+	bool approved;
+	u64 route;
+
+	/*
+	 * After NVM upgrade adding root switch device fails because we
+	 * initiated reset. During that time ICM might still send
+	 * XDomain connected message which we ignore here.
+	 */
+	if (!tb->root_switch)
+		return;
+
+	link = pkg->link_info & ICM_LINK_INFO_LINK_MASK;
+	depth = (pkg->link_info & ICM_LINK_INFO_DEPTH_MASK) >>
+		ICM_LINK_INFO_DEPTH_SHIFT;
+	approved = pkg->link_info & ICM_LINK_INFO_APPROVED;
+
+	if (link > ICM_MAX_LINK || depth > ICM_MAX_DEPTH) {
+		tb_warn(tb, "invalid topology %u.%u, ignoring\n", link, depth);
+		return;
+	}
+
+	route = get_route(pkg->local_route_hi, pkg->local_route_lo);
+
+	xd = tb_xdomain_find_by_uuid(tb, &pkg->remote_uuid);
+	if (xd) {
+		u8 xd_phy_port, phy_port;
+
+		xd_phy_port = phy_port_from_route(xd->route, xd->depth);
+		phy_port = phy_port_from_route(route, depth);
+
+		if (xd->depth == depth && xd_phy_port == phy_port) {
+			xd->link = link;
+			xd->route = route;
+			xd->is_unplugged = false;
+			tb_xdomain_put(xd);
+			return;
+		}
+
+		/*
+		 * If we find an existing XDomain connection remove it
+		 * now. We need to go through login handshake and
+		 * everything anyway to be able to re-establish the
+		 * connection.
+		 */
+		remove_xdomain(xd);
+		tb_xdomain_put(xd);
+	}
+
+	/*
+	 * Look if there already exists an XDomain in the same place
+	 * than the new one and in that case remove it because it is
+	 * most likely another host that got disconnected.
+	 */
+	xd = tb_xdomain_find_by_link_depth(tb, link, depth);
+	if (!xd) {
+		u8 dual_link;
+
+		dual_link = dual_link_from_link(link);
+		if (dual_link)
+			xd = tb_xdomain_find_by_link_depth(tb, dual_link,
+							   depth);
+	}
+	if (xd) {
+		remove_xdomain(xd);
+		tb_xdomain_put(xd);
+	}
+
+	/*
+	 * If the user disconnected a switch during suspend and
+	 * connected another host to the same port, remove the switch
+	 * first.
+	 */
+	sw = get_switch_at_route(tb->root_switch, route);
+	if (sw)
+		remove_switch(sw);
+
+	sw = tb_switch_find_by_link_depth(tb, link, depth);
+	if (!sw) {
+		tb_warn(tb, "no switch exists at %u.%u, ignoring\n", link,
+			depth);
+		return;
+	}
+
+	xd = tb_xdomain_alloc(sw->tb, &sw->dev, route,
+			      &pkg->local_uuid, &pkg->remote_uuid);
+	if (!xd) {
+		tb_switch_put(sw);
+		return;
+	}
+
+	xd->link = link;
+	xd->depth = depth;
+
+	tb_port_at(route, sw)->xdomain = xd;
+
+	tb_xdomain_add(xd);
+	tb_switch_put(sw);
+}
+
+static void
+icm_fr_xdomain_disconnected(struct tb *tb, const struct icm_pkg_header *hdr)
+{
+	const struct icm_fr_event_xdomain_disconnected *pkg =
+		(const struct icm_fr_event_xdomain_disconnected *)hdr;
+	struct tb_xdomain *xd;
+
+	/*
+	 * If the connection is through one or multiple devices, the
+	 * XDomain device is removed along with them so it is fine if we
+	 * cannot find it here.
+	 */
+	xd = tb_xdomain_find_by_uuid(tb, &pkg->remote_uuid);
+	if (xd) {
+		remove_xdomain(xd);
+		tb_xdomain_put(xd);
+	}
+}
+
 static struct pci_dev *get_upstream_port(struct pci_dev *pdev)
 {
 	struct pci_dev *parent;
@@ -594,6 +783,12 @@ static void icm_handle_notification(struct work_struct *work)
 	case ICM_EVENT_DEVICE_DISCONNECTED:
 		icm->device_disconnected(tb, n->pkg);
 		break;
+	case ICM_EVENT_XDOMAIN_CONNECTED:
+		icm->xdomain_connected(tb, n->pkg);
+		break;
+	case ICM_EVENT_XDOMAIN_DISCONNECTED:
+		icm->xdomain_disconnected(tb, n->pkg);
+		break;
 	}
 
 	mutex_unlock(&tb->lock);
@@ -927,6 +1122,10 @@ static void icm_unplug_children(struct tb_switch *sw)
 
 		if (tb_is_upstream_port(port))
 			continue;
+		if (port->xdomain) {
+			port->xdomain->is_unplugged = true;
+			continue;
+		}
 		if (!port->remote)
 			continue;
 
@@ -943,6 +1142,13 @@ static void icm_free_unplugged_children(struct tb_switch *sw)
 
 		if (tb_is_upstream_port(port))
 			continue;
+
+		if (port->xdomain && port->xdomain->is_unplugged) {
+			tb_xdomain_remove(port->xdomain);
+			port->xdomain = NULL;
+			continue;
+		}
+
 		if (!port->remote)
 			continue;
 
@@ -1009,8 +1215,10 @@ static int icm_start(struct tb *tb)
 	tb->root_switch->no_nvm_upgrade = x86_apple_machine;
 
 	ret = tb_switch_add(tb->root_switch);
-	if (ret)
+	if (ret) {
 		tb_switch_put(tb->root_switch);
+		tb->root_switch = NULL;
+	}
 
 	return ret;
 }
@@ -1042,6 +1250,8 @@ static const struct tb_cm_ops icm_fr_ops = {
 	.add_switch_key = icm_fr_add_switch_key,
 	.challenge_switch_key = icm_fr_challenge_switch_key,
 	.disconnect_pcie_paths = icm_disconnect_pcie_paths,
+	.approve_xdomain_paths = icm_fr_approve_xdomain_paths,
+	.disconnect_xdomain_paths = icm_fr_disconnect_xdomain_paths,
 };
 
 struct tb *icm_probe(struct tb_nhi *nhi)
@@ -1064,6 +1274,8 @@ struct tb *icm_probe(struct tb_nhi *nhi)
 		icm->get_route = icm_fr_get_route;
 		icm->device_connected = icm_fr_device_connected;
 		icm->device_disconnected = icm_fr_device_disconnected;
+		icm->xdomain_connected = icm_fr_xdomain_connected;
+		icm->xdomain_disconnected = icm_fr_xdomain_disconnected;
 		tb->cm_ops = &icm_fr_ops;
 		break;
 
@@ -1077,6 +1289,8 @@ struct tb *icm_probe(struct tb_nhi *nhi)
 		icm->get_route = icm_ar_get_route;
 		icm->device_connected = icm_fr_device_connected;
 		icm->device_disconnected = icm_fr_device_disconnected;
+		icm->xdomain_connected = icm_fr_xdomain_connected;
+		icm->xdomain_disconnected = icm_fr_xdomain_disconnected;
 		tb->cm_ops = &icm_fr_ops;
 		break;
 	}
diff --git a/drivers/thunderbolt/nhi.h b/drivers/thunderbolt/nhi.h
index 5b5bb2c436be..0e05828983db 100644
--- a/drivers/thunderbolt/nhi.h
+++ b/drivers/thunderbolt/nhi.h
@@ -157,6 +157,8 @@ enum nhi_mailbox_cmd {
 	NHI_MAILBOX_SAVE_DEVS = 0x05,
 	NHI_MAILBOX_DISCONNECT_PCIE_PATHS = 0x06,
 	NHI_MAILBOX_DRV_UNLOADS = 0x07,
+	NHI_MAILBOX_DISCONNECT_PA = 0x10,
+	NHI_MAILBOX_DISCONNECT_PB = 0x11,
 	NHI_MAILBOX_ALLOW_ALL_DEVS = 0x23,
 };
 
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 53f40c57df59..dfc357d33e1e 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -171,11 +171,11 @@ static int nvm_authenticate_host(struct tb_switch *sw)
 
 	/*
 	 * Root switch NVM upgrade requires that we disconnect the
-	 * existing PCIe paths first (in case it is not in safe mode
+	 * existing paths first (in case it is not in safe mode
 	 * already).
 	 */
 	if (!sw->safe_mode) {
-		ret = tb_domain_disconnect_pcie_paths(sw->tb);
+		ret = tb_domain_disconnect_all_paths(sw->tb);
 		if (ret)
 			return ret;
 		/*
@@ -1363,6 +1363,9 @@ void tb_switch_remove(struct tb_switch *sw)
 		if (sw->ports[i].remote)
 			tb_switch_remove(sw->ports[i].remote->sw);
 		sw->ports[i].remote = NULL;
+		if (sw->ports[i].xdomain)
+			tb_xdomain_remove(sw->ports[i].xdomain);
+		sw->ports[i].xdomain = NULL;
 	}
 
 	if (!sw->is_unplugged)
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index ea21d927bd09..74af9d4929ab 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -9,6 +9,7 @@
 
 #include <linux/nvmem-provider.h>
 #include <linux/pci.h>
+#include <linux/thunderbolt.h>
 #include <linux/uuid.h>
 
 #include "tb_regs.h"
@@ -109,14 +110,25 @@ struct tb_switch {
 
 /**
  * struct tb_port - a thunderbolt port, part of a tb_switch
+ * @config: Cached port configuration read from registers
+ * @sw: Switch the port belongs to
+ * @remote: Remote port (%NULL if not connected)
+ * @xdomain: Remote host (%NULL if not connected)
+ * @cap_phy: Offset, zero if not found
+ * @port: Port number on switch
+ * @disabled: Disabled by eeprom
+ * @dual_link_port: If the switch is connected using two ports, points
+ *		    to the other port.
+ * @link_nr: Is this primary or secondary port on the dual_link.
  */
 struct tb_port {
 	struct tb_regs_port_header config;
 	struct tb_switch *sw;
-	struct tb_port *remote; /* remote port, NULL if not connected */
-	int cap_phy; /* offset, zero if not found */
-	u8 port; /* port number on switch */
-	bool disabled; /* disabled by eeprom */
+	struct tb_port *remote;
+	struct tb_xdomain *xdomain;
+	int cap_phy;
+	u8 port;
+	bool disabled;
 	struct tb_port *dual_link_port;
 	u8 link_nr:1;
 };
@@ -189,6 +201,8 @@ struct tb_path {
  * @add_switch_key: Add key to switch
  * @challenge_switch_key: Challenge switch using key
  * @disconnect_pcie_paths: Disconnects PCIe paths before NVM update
+ * @approve_xdomain_paths: Approve (establish) XDomain DMA paths
+ * @disconnect_xdomain_paths: Disconnect XDomain DMA paths
  */
 struct tb_cm_ops {
 	int (*driver_ready)(struct tb *tb);
@@ -205,6 +219,8 @@ struct tb_cm_ops {
 	int (*challenge_switch_key)(struct tb *tb, struct tb_switch *sw,
 				    const u8 *challenge, u8 *response);
 	int (*disconnect_pcie_paths)(struct tb *tb);
+	int (*approve_xdomain_paths)(struct tb *tb, struct tb_xdomain *xd);
+	int (*disconnect_xdomain_paths)(struct tb *tb, struct tb_xdomain *xd);
 };
 
 static inline void *tb_priv(struct tb *tb)
@@ -331,6 +347,8 @@ extern struct device_type tb_switch_type;
 int tb_domain_init(void);
 void tb_domain_exit(void);
 void tb_switch_exit(void);
+int tb_xdomain_init(void);
+void tb_xdomain_exit(void);
 
 struct tb *tb_domain_alloc(struct tb_nhi *nhi, size_t privsize);
 int tb_domain_add(struct tb *tb);
@@ -343,6 +361,9 @@ int tb_domain_approve_switch(struct tb *tb, struct tb_switch *sw);
 int tb_domain_approve_switch_key(struct tb *tb, struct tb_switch *sw);
 int tb_domain_challenge_switch_key(struct tb *tb, struct tb_switch *sw);
 int tb_domain_disconnect_pcie_paths(struct tb *tb);
+int tb_domain_approve_xdomain_paths(struct tb *tb, struct tb_xdomain *xd);
+int tb_domain_disconnect_xdomain_paths(struct tb *tb, struct tb_xdomain *xd);
+int tb_domain_disconnect_all_paths(struct tb *tb);
 
 static inline void tb_domain_put(struct tb *tb)
 {
@@ -422,4 +443,14 @@ static inline u64 tb_downstream_route(struct tb_port *port)
 	       | ((u64) port->port << (port->sw->config.depth * 8));
 }
 
+bool tb_xdomain_handle_request(struct tb *tb, enum tb_cfg_pkg_type type,
+			       const void *buf, size_t size);
+struct tb_xdomain *tb_xdomain_alloc(struct tb *tb, struct device *parent,
+				    u64 route, const uuid_t *local_uuid,
+				    const uuid_t *remote_uuid);
+void tb_xdomain_add(struct tb_xdomain *xd);
+void tb_xdomain_remove(struct tb_xdomain *xd);
+struct tb_xdomain *tb_xdomain_find_by_link_depth(struct tb *tb, u8 link,
+						 u8 depth);
+
 #endif
diff --git a/drivers/thunderbolt/tb_msgs.h b/drivers/thunderbolt/tb_msgs.h
index f2b2550cd97c..b0a092baa605 100644
--- a/drivers/thunderbolt/tb_msgs.h
+++ b/drivers/thunderbolt/tb_msgs.h
@@ -101,11 +101,14 @@ enum icm_pkg_code {
 	ICM_CHALLENGE_DEVICE = 0x5,
 	ICM_ADD_DEVICE_KEY = 0x6,
 	ICM_GET_ROUTE = 0xa,
+	ICM_APPROVE_XDOMAIN = 0x10,
 };
 
 enum icm_event_code {
 	ICM_EVENT_DEVICE_CONNECTED = 3,
 	ICM_EVENT_DEVICE_DISCONNECTED = 4,
+	ICM_EVENT_XDOMAIN_CONNECTED = 6,
+	ICM_EVENT_XDOMAIN_DISCONNECTED = 7,
 };
 
 struct icm_pkg_header {
@@ -188,6 +191,25 @@ struct icm_fr_event_device_disconnected {
 	u16 link_info;
 };
 
+struct icm_fr_event_xdomain_connected {
+	struct icm_pkg_header hdr;
+	u16 reserved;
+	u16 link_info;
+	uuid_t remote_uuid;
+	uuid_t local_uuid;
+	u32 local_route_hi;
+	u32 local_route_lo;
+	u32 remote_route_hi;
+	u32 remote_route_lo;
+};
+
+struct icm_fr_event_xdomain_disconnected {
+	struct icm_pkg_header hdr;
+	u16 reserved;
+	u16 link_info;
+	uuid_t remote_uuid;
+};
+
 struct icm_fr_pkg_add_device_key {
 	struct icm_pkg_header hdr;
 	uuid_t ep_uuid;
@@ -224,6 +246,28 @@ struct icm_fr_pkg_challenge_device_response {
 	u32 response[8];
 };
 
+struct icm_fr_pkg_approve_xdomain {
+	struct icm_pkg_header hdr;
+	u16 reserved;
+	u16 link_info;
+	uuid_t remote_uuid;
+	u16 transmit_path;
+	u16 transmit_ring;
+	u16 receive_path;
+	u16 receive_ring;
+};
+
+struct icm_fr_pkg_approve_xdomain_response {
+	struct icm_pkg_header hdr;
+	u16 reserved;
+	u16 link_info;
+	uuid_t remote_uuid;
+	u16 transmit_path;
+	u16 transmit_ring;
+	u16 receive_path;
+	u16 receive_ring;
+};
+
 /* Alpine Ridge only messages */
 
 struct icm_ar_pkg_get_route {
@@ -240,4 +284,83 @@ struct icm_ar_pkg_get_route_response {
 	u32 route_lo;
 };
 
+/* XDomain messages */
+
+struct tb_xdomain_header {
+	u32 route_hi;
+	u32 route_lo;
+	u32 length_sn;
+};
+
+#define TB_XDOMAIN_LENGTH_MASK	GENMASK(5, 0)
+#define TB_XDOMAIN_SN_MASK	GENMASK(28, 27)
+#define TB_XDOMAIN_SN_SHIFT	27
+
+enum tb_xdp_type {
+	UUID_REQUEST_OLD = 1,
+	UUID_RESPONSE = 2,
+	PROPERTIES_REQUEST,
+	PROPERTIES_RESPONSE,
+	PROPERTIES_CHANGED_REQUEST,
+	PROPERTIES_CHANGED_RESPONSE,
+	ERROR_RESPONSE,
+	UUID_REQUEST = 12,
+};
+
+struct tb_xdp_header {
+	struct tb_xdomain_header xd_hdr;
+	uuid_t uuid;
+	u32 type;
+};
+
+struct tb_xdp_properties {
+	struct tb_xdp_header hdr;
+	uuid_t src_uuid;
+	uuid_t dst_uuid;
+	u16 offset;
+	u16 reserved;
+};
+
+struct tb_xdp_properties_response {
+	struct tb_xdp_header hdr;
+	uuid_t src_uuid;
+	uuid_t dst_uuid;
+	u16 offset;
+	u16 data_length;
+	u32 generation;
+	u32 data[0];
+};
+
+/*
+ * Max length of data array single XDomain property response is allowed
+ * to carry.
+ */
+#define TB_XDP_PROPERTIES_MAX_DATA_LENGTH	\
+	(((256 - 4 - sizeof(struct tb_xdp_properties_response))) / 4)
+
+/* Maximum size of the total property block in dwords we allow */
+#define TB_XDP_PROPERTIES_MAX_LENGTH		500
+
+struct tb_xdp_properties_changed {
+	struct tb_xdp_header hdr;
+	uuid_t src_uuid;
+};
+
+struct tb_xdp_properties_changed_response {
+	struct tb_xdp_header hdr;
+};
+
+enum tb_xdp_error {
+	ERROR_SUCCESS,
+	ERROR_UNKNOWN_PACKET,
+	ERROR_UNKNOWN_DOMAIN,
+	ERROR_NOT_SUPPORTED,
+	ERROR_NOT_READY,
+};
+
+struct tb_xdp_error_response {
+	struct tb_xdp_header hdr;
+	u32 error;
+};
+
 #endif
diff --git a/drivers/thunderbolt/xdomain.c b/drivers/thunderbolt/xdomain.c
new file mode 100644
index 000000000000..f2d06f6f7be9
--- /dev/null
+++ b/drivers/thunderbolt/xdomain.c
@@ -0,0 +1,1576 @@
+/*
+ * Thunderbolt XDomain discovery protocol support
+ *
+ * Copyright (C) 2017, Intel Corporation
+ * Authors: Michael Jamet <michael.jamet@intel.com>
+ *          Mika Westerberg <mika.westerberg@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/kmod.h>
+#include <linux/module.h>
+#include <linux/utsname.h>
+#include <linux/uuid.h>
+#include <linux/workqueue.h>
+
+#include "tb.h"
+
+#define XDOMAIN_DEFAULT_TIMEOUT			5000 /* ms */
+#define XDOMAIN_PROPERTIES_RETRIES		60
+#define XDOMAIN_PROPERTIES_CHANGED_RETRIES	10
+
+struct xdomain_request_work {
+	struct work_struct work;
+	struct tb_xdp_header *pkg;
+	struct tb *tb;
+};
+
+/* Serializes access to the properties and protocol handlers below */
+static DEFINE_MUTEX(xdomain_lock);
+
+/* Properties exposed to the remote domains */
+static struct tb_property_dir *xdomain_property_dir;
+static u32 *xdomain_property_block;
+static u32 xdomain_property_block_len;
+static u32 xdomain_property_block_gen;
+
+/* Additional protocol handlers */
+static LIST_HEAD(protocol_handlers);
+
+/* UUID for XDomain discovery protocol: b638d70e-42ff-40bb-97c2-90e2c0b2ff07 */
+static const uuid_t tb_xdp_uuid =
+	UUID_INIT(0xb638d70e, 0x42ff, 0x40bb,
+		  0x97, 0xc2, 0x90, 0xe2, 0xc0, 0xb2, 0xff, 0x07);
+
+static bool tb_xdomain_match(const struct tb_cfg_request *req,
+			     const struct ctl_pkg *pkg)
+{
+	switch (pkg->frame.eof) {
+	case TB_CFG_PKG_ERROR:
+		return true;
+
+	case TB_CFG_PKG_XDOMAIN_RESP: {
+		const struct tb_xdp_header *res_hdr = pkg->buffer;
+		const struct tb_xdp_header *req_hdr = req->request;
+		u8 req_seq, res_seq;
+
+		if (pkg->frame.size < req->response_size / 4)
+			return false;
+
+		/* Make sure route matches */
+		if ((res_hdr->xd_hdr.route_hi & ~BIT(31)) !=
+		     req_hdr->xd_hdr.route_hi)
+			return false;
+		if ((res_hdr->xd_hdr.route_lo) != req_hdr->xd_hdr.route_lo)
+			return false;
+
+		/* Then check that the sequence number matches */
+		res_seq = res_hdr->xd_hdr.length_sn & TB_XDOMAIN_SN_MASK;
+		res_seq >>= TB_XDOMAIN_SN_SHIFT;
+		req_seq = req_hdr->xd_hdr.length_sn & TB_XDOMAIN_SN_MASK;
+		req_seq >>= TB_XDOMAIN_SN_SHIFT;
+		if (res_seq != req_seq)
+			return false;
+
+		/* Check that the XDomain protocol matches */
+		if (!uuid_equal(&res_hdr->uuid, &req_hdr->uuid))
+			return false;
+
+		return true;
+	}
+
+	default:
+		return false;
+	}
+}
+
+static bool tb_xdomain_copy(struct tb_cfg_request *req,
+			    const struct ctl_pkg *pkg)
+{
+	memcpy(req->response, pkg->buffer, req->response_size);
+	req->result.err = 0;
+	return true;
+}
+
+static void response_ready(void *data)
+{
+	tb_cfg_request_put(data);
+}
+
+static int __tb_xdomain_response(struct tb_ctl *ctl, const void *response,
+				 size_t size, enum tb_cfg_pkg_type type)
+{
+	struct tb_cfg_request *req;
+
+	req = tb_cfg_request_alloc();
+	if (!req)
+		return -ENOMEM;
+
+	req->match = tb_xdomain_match;
+	req->copy = tb_xdomain_copy;
+	req->request = response;
+	req->request_size = size;
+	req->request_type = type;
+
+	return tb_cfg_request(ctl, req, response_ready, req);
+}
+
+/**
+ * tb_xdomain_response() - Send a XDomain response message
+ * @xd: XDomain to send the message
+ * @response: Response to send
+ * @size: Size of the response
+ * @type: PDF type of the response
+ *
+ * This can be used to send a XDomain response message to the other
+ * domain. No response for the message is expected.
+ *
+ * Return: %0 in case of success and negative errno in case of failure
+ */
+int tb_xdomain_response(struct tb_xdomain *xd, const void *response,
+			size_t size, enum tb_cfg_pkg_type type)
+{
+	return __tb_xdomain_response(xd->tb->ctl, response, size, type);
+}
+EXPORT_SYMBOL_GPL(tb_xdomain_response);
+
+static int __tb_xdomain_request(struct tb_ctl *ctl, const void *request,
+	size_t request_size, enum tb_cfg_pkg_type request_type, void *response,
+	size_t response_size, enum tb_cfg_pkg_type response_type,
+	unsigned int timeout_msec)
+{
+	struct tb_cfg_request *req;
+	struct tb_cfg_result res;
+
+	req = tb_cfg_request_alloc();
+	if (!req)
+		return -ENOMEM;
+
+	req->match = tb_xdomain_match;
+	req->copy = tb_xdomain_copy;
+	req->request = request;
+	req->request_size = request_size;
+	req->request_type = request_type;
+	req->response = response;
+	req->response_size = response_size;
+	req->response_type = response_type;
+
+	res = tb_cfg_request_sync(ctl, req, timeout_msec);
+
+	tb_cfg_request_put(req);
+
+	return res.err == 1 ? -EIO : res.err;
+}
+
+/**
+ * tb_xdomain_request() - Send a XDomain request
+ * @xd: XDomain to send the request
+ * @request: Request to send
+ * @request_size: Size of the request in bytes
+ * @request_type: PDF type of the request
+ * @response: Response is copied here
+ * @response_size: Expected size of the response in bytes
+ * @response_type: Expected PDF type of the response
+ * @timeout_msec: Timeout in milliseconds to wait for the response
+ *
+ * This function can be used to send XDomain control channel messages to
+ * the other domain. The function waits until the response is received
+ * or when timeout triggers. Whichever comes first.
+ *
+ * Return: %0 in case of success and negative errno in case of failure
+ */
+int tb_xdomain_request(struct tb_xdomain *xd, const void *request,
+	size_t request_size, enum tb_cfg_pkg_type request_type,
+	void *response, size_t response_size,
+	enum tb_cfg_pkg_type response_type, unsigned int timeout_msec)
+{
+	return __tb_xdomain_request(xd->tb->ctl, request, request_size,
+				    request_type, response, response_size,
+				    response_type, timeout_msec);
+}
+EXPORT_SYMBOL_GPL(tb_xdomain_request);
+
+static inline void tb_xdp_fill_header(struct tb_xdp_header *hdr, u64 route,
+	u8 sequence, enum tb_xdp_type type, size_t size)
+{
+	u32 length_sn;
+
+	length_sn = (size - sizeof(hdr->xd_hdr)) / 4;
+	length_sn |= (sequence << TB_XDOMAIN_SN_SHIFT) & TB_XDOMAIN_SN_MASK;
+
+	hdr->xd_hdr.route_hi = upper_32_bits(route);
+	hdr->xd_hdr.route_lo = lower_32_bits(route);
+	hdr->xd_hdr.length_sn = length_sn;
+	hdr->type = type;
+	memcpy(&hdr->uuid, &tb_xdp_uuid, sizeof(tb_xdp_uuid));
+}
+
+static int tb_xdp_handle_error(const struct tb_xdp_header *hdr)
+{
+	const struct tb_xdp_error_response *error;
+
+	if (hdr->type != ERROR_RESPONSE)
+		return 0;
+
+	error = (const struct tb_xdp_error_response *)hdr;
+
+	switch (error->error) {
+	case ERROR_UNKNOWN_PACKET:
+	case ERROR_UNKNOWN_DOMAIN:
+		return -EIO;
+	case ERROR_NOT_SUPPORTED:
+		return -ENOTSUPP;
+	case ERROR_NOT_READY:
+		return -EAGAIN;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int tb_xdp_error_response(struct tb_ctl *ctl, u64 route, u8 sequence,
+				 enum tb_xdp_error error)
+{
+	struct tb_xdp_error_response res;
+
+	memset(&res, 0, sizeof(res));
+	tb_xdp_fill_header(&res.hdr, route, sequence, ERROR_RESPONSE,
+			   sizeof(res));
+	res.error = error;
+
+	return __tb_xdomain_response(ctl, &res, sizeof(res),
+				     TB_CFG_PKG_XDOMAIN_RESP);
+}
+
+static int tb_xdp_properties_request(struct tb_ctl *ctl, u64 route,
+	const uuid_t *src_uuid, const uuid_t *dst_uuid, int retry,
+	u32 **block, u32 *generation)
+{
+	struct tb_xdp_properties_response *res;
+	struct tb_xdp_properties req;
+	u16 data_len, len;
+	size_t total_size;
+	u32 *data = NULL;
+	int ret;
+
+	total_size = sizeof(*res) + TB_XDP_PROPERTIES_MAX_DATA_LENGTH * 4;
+	res = kzalloc(total_size, GFP_KERNEL);
+	if (!res)
+		return -ENOMEM;
+
+	memset(&req, 0, sizeof(req));
+	tb_xdp_fill_header(&req.hdr, route, retry % 4, PROPERTIES_REQUEST,
+			   sizeof(req));
+	memcpy(&req.src_uuid, src_uuid, sizeof(*src_uuid));
+	memcpy(&req.dst_uuid, dst_uuid, sizeof(*dst_uuid));
+
+	len = 0;
+	data_len = 0;
+
+	do {
+		ret = __tb_xdomain_request(ctl, &req, sizeof(req),
+					   TB_CFG_PKG_XDOMAIN_REQ, res,
+					   total_size, TB_CFG_PKG_XDOMAIN_RESP,
+					   XDOMAIN_DEFAULT_TIMEOUT);
+		if (ret)
+			goto err;
+
+		ret = tb_xdp_handle_error(&res->hdr);
+		if (ret)
+			goto err;
+
+		/*
+		 * Package length includes the whole payload without the
+		 * XDomain header. Validate first that the package is at
+		 * least size of the response structure.
+		 */
+		len = res->hdr.xd_hdr.length_sn & TB_XDOMAIN_LENGTH_MASK;
+		if (len < sizeof(*res) / 4) {
+			ret = -EINVAL;
+			goto err;
+		}
+
+		len += sizeof(res->hdr.xd_hdr) / 4;
+		len -= sizeof(*res) / 4;
+
+		if (res->offset != req.offset) {
+			ret = -EINVAL;
+			goto err;
+		}
+
+		/*
+		 * First time allocate block that has enough space for
+		 * the whole properties block.
+		 */
+		if (!data) {
+			data_len = res->data_length;
+			if (data_len > TB_XDP_PROPERTIES_MAX_LENGTH) {
+				ret = -E2BIG;
+				goto err;
+			}
+
+			data = kcalloc(data_len, sizeof(u32), GFP_KERNEL);
+			if (!data) {
+				ret = -ENOMEM;
+				goto err;
+			}
+		}
+
+		memcpy(data + req.offset, res->data, len * 4);
+		req.offset += len;
+	} while (!data_len || req.offset < data_len);
+
+	*block = data;
+	*generation = res->generation;
+
+	kfree(res);
+
+	return data_len;
+
+err:
+	kfree(data);
+	kfree(res);
+
+	return ret;
+}
+
+static int tb_xdp_properties_response(struct tb *tb, struct tb_ctl *ctl,
+	u64 route, u8 sequence, const uuid_t *src_uuid,
+	const struct tb_xdp_properties *req)
+{
+	struct tb_xdp_properties_response *res;
+	size_t total_size;
+	u16 len;
+	int ret;
+
+	/*
+	 * Currently we expect all requests to be directed to us. The
+	 * protocol supports forwarding, though which we might add
+	 * support later on.
+	 */
+	if (!uuid_equal(src_uuid, &req->dst_uuid)) {
+		tb_xdp_error_response(ctl, route, sequence,
+				      ERROR_UNKNOWN_DOMAIN);
+		return 0;
+	}
+
+	mutex_lock(&xdomain_lock);
+
+	if (req->offset >= xdomain_property_block_len) {
+		mutex_unlock(&xdomain_lock);
+		return -EINVAL;
+	}
+
+	len = xdomain_property_block_len - req->offset;
+	len = min_t(u16, len, TB_XDP_PROPERTIES_MAX_DATA_LENGTH);
+	total_size = sizeof(*res) + len * 4;
+
+	res = kzalloc(total_size, GFP_KERNEL);
+	if (!res) {
+		mutex_unlock(&xdomain_lock);
+		return -ENOMEM;
+	}
+
+	tb_xdp_fill_header(&res->hdr, route, sequence, PROPERTIES_RESPONSE,
+			   total_size);
+	res->generation = xdomain_property_block_gen;
+	res->data_length = xdomain_property_block_len;
+	res->offset = req->offset;
+	uuid_copy(&res->src_uuid, src_uuid);
+	uuid_copy(&res->dst_uuid, &req->src_uuid);
+	memcpy(res->data, &xdomain_property_block[req->offset], len * 4);
+
+	mutex_unlock(&xdomain_lock);
+
+	ret = __tb_xdomain_response(ctl, res, total_size,
+				    TB_CFG_PKG_XDOMAIN_RESP);
+
+	kfree(res);
+	return ret;
+}
+
+static int tb_xdp_properties_changed_request(struct tb_ctl *ctl, u64 route,
+					     int retry, const uuid_t *uuid)
+{
+	struct tb_xdp_properties_changed_response res;
+	struct tb_xdp_properties_changed req;
+	int ret;
+
+	memset(&req, 0, sizeof(req));
+	tb_xdp_fill_header(&req.hdr, route, retry % 4,
+			   PROPERTIES_CHANGED_REQUEST, sizeof(req));
+	uuid_copy(&req.src_uuid, uuid);
+
+	memset(&res, 0, sizeof(res));
+	ret = __tb_xdomain_request(ctl, &req, sizeof(req),
+				   TB_CFG_PKG_XDOMAIN_REQ, &res, sizeof(res),
+				   TB_CFG_PKG_XDOMAIN_RESP,
+				   XDOMAIN_DEFAULT_TIMEOUT);
+	if (ret)
+		return ret;
+
+	return tb_xdp_handle_error(&res.hdr);
+}
+
+static int
+tb_xdp_properties_changed_response(struct tb_ctl *ctl, u64 route, u8 sequence)
+{
+	struct tb_xdp_properties_changed_response res;
+
+	memset(&res, 0, sizeof(res));
+	tb_xdp_fill_header(&res.hdr, route, sequence,
+			   PROPERTIES_CHANGED_RESPONSE, sizeof(res));
+	return __tb_xdomain_response(ctl, &res, sizeof(res),
+				     TB_CFG_PKG_XDOMAIN_RESP);
+}
+
+/**
+ * tb_register_protocol_handler() - Register protocol handler
+ * @handler: Handler to register
+ *
+ * This allows XDomain service drivers to hook into incoming XDomain
+ * messages. After this function is called the service driver needs to
+ * be able to handle calls to callback whenever a package with the
+ * registered protocol is received.
+ */
+int tb_register_protocol_handler(struct tb_protocol_handler *handler)
+{
+	if (!handler->uuid || !handler->callback)
+		return -EINVAL;
+	if (uuid_equal(handler->uuid, &tb_xdp_uuid))
+		return -EINVAL;
+
+	mutex_lock(&xdomain_lock);
+	list_add_tail(&handler->list, &protocol_handlers);
+	mutex_unlock(&xdomain_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tb_register_protocol_handler);
+
+/**
+ * tb_unregister_protocol_handler() - Unregister protocol handler
+ * @handler: Handler to unregister
+ *
+ * Removes the previously registered protocol handler.
+ */
+void tb_unregister_protocol_handler(struct tb_protocol_handler *handler)
+{
+	mutex_lock(&xdomain_lock);
+	list_del_init(&handler->list);
+	mutex_unlock(&xdomain_lock);
+}
+EXPORT_SYMBOL_GPL(tb_unregister_protocol_handler);
+
+static void tb_xdp_handle_request(struct work_struct *work)
+{
+	struct xdomain_request_work *xw = container_of(work, typeof(*xw), work);
+	const struct tb_xdp_header *pkg = xw->pkg;
+	const struct tb_xdomain_header *xhdr = &pkg->xd_hdr;
+	struct tb *tb = xw->tb;
+	struct tb_ctl *ctl = tb->ctl;
+	const uuid_t *uuid;
+	int ret = 0;
+	u8 sequence;
+	u64 route;
+
+	route = ((u64)xhdr->route_hi << 32 | xhdr->route_lo) & ~BIT_ULL(63);
+	sequence = xhdr->length_sn & TB_XDOMAIN_SN_MASK;
+	sequence >>= TB_XDOMAIN_SN_SHIFT;
+
+	mutex_lock(&tb->lock);
+	if (tb->root_switch)
+		uuid = tb->root_switch->uuid;
+	else
+		uuid = NULL;
+	mutex_unlock(&tb->lock);
+
+	if (!uuid) {
+		tb_xdp_error_response(ctl, route, sequence, ERROR_NOT_READY);
+		goto out;
+	}
+
+	switch (pkg->type) {
+	case PROPERTIES_REQUEST:
+		ret = tb_xdp_properties_response(tb, ctl, route, sequence, uuid,
+			(const struct tb_xdp_properties *)pkg);
+		break;
+
+	case PROPERTIES_CHANGED_REQUEST: {
+		const struct tb_xdp_properties_changed *xchg =
+			(const struct tb_xdp_properties_changed *)pkg;
+		struct tb_xdomain *xd;
+
+		ret = tb_xdp_properties_changed_response(ctl, route, sequence);
+
+		/*
+		 * Since the properties have been changed, let's update
+		 * the xdomain related to this connection as well in
+		 * case there is a change in services it offers.
+		 */
+		xd = tb_xdomain_find_by_uuid_locked(tb, &xchg->src_uuid);
+		if (xd) {
+			queue_delayed_work(tb->wq, &xd->get_properties_work,
+					   msecs_to_jiffies(50));
+			tb_xdomain_put(xd);
+		}
+
+		break;
+	}
+
+	default:
+		break;
+	}
+
+	if (ret) {
+		tb_warn(tb, "failed to send XDomain response for %#x\n",
+			pkg->type);
+	}
+
+out:
+	kfree(xw->pkg);
+	kfree(xw);
+}
+
+static void
+tb_xdp_schedule_request(struct tb *tb, const struct tb_xdp_header *hdr,
+			size_t size)
+{
+	struct xdomain_request_work *xw;
+
+	xw = kmalloc(sizeof(*xw), GFP_KERNEL);
+	if (!xw)
+		return;
+
+	INIT_WORK(&xw->work, tb_xdp_handle_request);
+	xw->pkg = kmemdup(hdr, size, GFP_KERNEL);
+	xw->tb = tb;
+
+	queue_work(tb->wq, &xw->work);
+}
+
+/**
+ * tb_register_service_driver() - Register XDomain service driver
+ * @drv: Driver to register
+ *
+ * Registers new service driver from @drv to the bus.
+ */
+int tb_register_service_driver(struct tb_service_driver *drv)
+{
+	drv->driver.bus = &tb_bus_type;
+	return driver_register(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(tb_register_service_driver);
+
+/**
+ * tb_unregister_service_driver() - Unregister XDomain service driver
+ * @xdrv: Driver to unregister
+ *
+ * Unregisters XDomain service driver from the bus.
+ */
+void tb_unregister_service_driver(struct tb_service_driver *drv)
+{
+	driver_unregister(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(tb_unregister_service_driver);
+
+static ssize_t key_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+
+	/*
+	 * It should be null terminated but anything else is pretty much
+	 * allowed.
+	 */
+	return sprintf(buf, "%*pEp\n", (int)strlen(svc->key), svc->key);
+}
+static DEVICE_ATTR_RO(key);
+
+static int get_modalias(struct tb_service *svc, char *buf, size_t size)
+{
+	return snprintf(buf, size, "tbsvc:k%sp%08Xv%08Xr%08X", svc->key,
+			svc->prtcid, svc->prtcvers, svc->prtcrevs);
+}
+
+static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+
+	/* Full buffer size except new line and null termination */
+	get_modalias(svc, buf, PAGE_SIZE - 2);
+	return sprintf(buf, "%s\n", buf);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static ssize_t prtcid_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+
+	return sprintf(buf, "%u\n", svc->prtcid);
+}
+static DEVICE_ATTR_RO(prtcid);
+
+static ssize_t prtcvers_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+
+	return sprintf(buf, "%u\n", svc->prtcvers);
+}
+static DEVICE_ATTR_RO(prtcvers);
+
+static ssize_t prtcrevs_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+
+	return sprintf(buf, "%u\n", svc->prtcrevs);
+}
+static DEVICE_ATTR_RO(prtcrevs);
+
+static ssize_t prtcstns_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+
+	return sprintf(buf, "0x%08x\n", svc->prtcstns);
+}
+static DEVICE_ATTR_RO(prtcstns);
+
+static struct attribute *tb_service_attrs[] = {
+	&dev_attr_key.attr,
+	&dev_attr_modalias.attr,
+	&dev_attr_prtcid.attr,
+	&dev_attr_prtcvers.attr,
+	&dev_attr_prtcrevs.attr,
+	&dev_attr_prtcstns.attr,
+	NULL,
+};
+
+static struct attribute_group tb_service_attr_group = {
+	.attrs = tb_service_attrs,
+};
+
+static const struct attribute_group *tb_service_attr_groups[] = {
+	&tb_service_attr_group,
+	NULL,
+};
+
+static int tb_service_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+	char modalias[64];
+
+	get_modalias(svc, modalias, sizeof(modalias));
+	return add_uevent_var(env, "MODALIAS=%s", modalias);
+}
+
+static void tb_service_release(struct device *dev)
+{
+	struct tb_service *svc = container_of(dev, struct tb_service, dev);
+	struct tb_xdomain *xd = tb_service_parent(svc);
+
+	ida_simple_remove(&xd->service_ids, svc->id);
+	kfree(svc->key);
+	kfree(svc);
+}
+
+struct device_type tb_service_type = {
+	.name = "thunderbolt_service",
+	.groups = tb_service_attr_groups,
+	.uevent = tb_service_uevent,
+	.release = tb_service_release,
+};
+EXPORT_SYMBOL_GPL(tb_service_type);
+
+static int remove_missing_service(struct device *dev, void *data)
+{
+	struct tb_xdomain *xd = data;
+	struct tb_service *svc;
+
+	svc = tb_to_service(dev);
+	if (!svc)
+		return 0;
+
+	if (!tb_property_find(xd->properties, svc->key,
+			      TB_PROPERTY_TYPE_DIRECTORY))
+		device_unregister(dev);
+
+	return 0;
+}
+
+static int find_service(struct device *dev, void *data)
+{
+	const struct tb_property *p = data;
+	struct tb_service *svc;
+
+	svc = tb_to_service(dev);
+	if (!svc)
+		return 0;
+
+	return !strcmp(svc->key, p->key);
+}
+
+static int populate_service(struct tb_service *svc,
+			    struct tb_property *property)
+{
+	struct tb_property_dir *dir = property->value.dir;
+	struct tb_property *p;
+
+	/* Fill in standard properties */
+	p = tb_property_find(dir, "prtcid", TB_PROPERTY_TYPE_VALUE);
+	if (p)
+		svc->prtcid = p->value.immediate;
+	p = tb_property_find(dir, "prtcvers", TB_PROPERTY_TYPE_VALUE);
+	if (p)
+		svc->prtcvers = p->value.immediate;
+	p = tb_property_find(dir, "prtcrevs", TB_PROPERTY_TYPE_VALUE);
+	if (p)
+		svc->prtcrevs = p->value.immediate;
+	p = tb_property_find(dir, "prtcstns", TB_PROPERTY_TYPE_VALUE);
+	if (p)
+		svc->prtcstns = p->value.immediate;
+
+	svc->key = kstrdup(property->key, GFP_KERNEL);
+	if (!svc->key)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void enumerate_services(struct tb_xdomain *xd)
+{
+	struct tb_service *svc;
+	struct tb_property *p;
+	struct device *dev;
+
+	/*
+	 * First remove all services that are not available anymore in
+	 * the updated property block.
+	 */
+	device_for_each_child_reverse(&xd->dev, xd, remove_missing_service);
+
+	/* Then re-enumerate properties creating new services as we go */
+	tb_property_for_each(xd->properties, p) {
+		if (p->type != TB_PROPERTY_TYPE_DIRECTORY)
+			continue;
+
+		/* If the service exists already we are fine */
+		dev = device_find_child(&xd->dev, p, find_service);
+		if (dev) {
+			put_device(dev);
+			continue;
+		}
+
+		svc = kzalloc(sizeof(*svc), GFP_KERNEL);
+		if (!svc)
+			break;
+
+		if (populate_service(svc, p)) {
+			kfree(svc);
+			break;
+		}
+
+		svc->id = ida_simple_get(&xd->service_ids, 0, 0, GFP_KERNEL);
+		svc->dev.bus = &tb_bus_type;
+		svc->dev.type = &tb_service_type;
+		svc->dev.parent = &xd->dev;
+		dev_set_name(&svc->dev, "%s.%d", dev_name(&xd->dev), svc->id);
+
+		if (device_register(&svc->dev)) {
+			put_device(&svc->dev);
+			break;
+		}
+	}
+}
+
+static int populate_properties(struct tb_xdomain *xd,
+			       struct tb_property_dir *dir)
+{
+	const struct tb_property *p;
+
+	/* Required properties */
+	p = tb_property_find(dir, "deviceid", TB_PROPERTY_TYPE_VALUE);
+	if (!p)
+		return -EINVAL;
+	xd->device = p->value.immediate;
+
+	p = tb_property_find(dir, "vendorid", TB_PROPERTY_TYPE_VALUE);
+	if (!p)
+		return -EINVAL;
+	xd->vendor = p->value.immediate;
+
+	kfree(xd->device_name);
+	xd->device_name = NULL;
+	kfree(xd->vendor_name);
+	xd->vendor_name = NULL;
+
+	/* Optional properties */
+	p = tb_property_find(dir, "deviceid", TB_PROPERTY_TYPE_TEXT);
+	if (p)
+		xd->device_name = kstrdup(p->value.text, GFP_KERNEL);
+	p = tb_property_find(dir, "vendorid", TB_PROPERTY_TYPE_TEXT);
+	if (p)
+		xd->vendor_name = kstrdup(p->value.text, GFP_KERNEL);
+
+	return 0;
+}
+
+/* Called with @xd->lock held */
+static void tb_xdomain_restore_paths(struct tb_xdomain *xd)
+{
+	if (!xd->resume)
+		return;
+
+	xd->resume = false;
+	if (xd->transmit_path) {
+		dev_dbg(&xd->dev, "re-establishing DMA path\n");
+		tb_domain_approve_xdomain_paths(xd->tb, xd);
+	}
+}
+
+static void tb_xdomain_get_properties(struct work_struct *work)
+{
+	struct tb_xdomain *xd = container_of(work, typeof(*xd),
+					     get_properties_work.work);
+	struct tb_property_dir *dir;
+	struct tb *tb = xd->tb;
+	bool update = false;
+	u32 *block = NULL;
+	u32 gen = 0;
+	int ret;
+
+	ret = tb_xdp_properties_request(tb->ctl, xd->route, xd->local_uuid,
+					xd->remote_uuid, xd->properties_retries,
+					&block, &gen);
+	if (ret < 0) {
+		if (xd->properties_retries-- > 0) {
+			queue_delayed_work(xd->tb->wq, &xd->get_properties_work,
+					   msecs_to_jiffies(1000));
+		} else {
+			/* Give up now */
+			dev_err(&xd->dev,
+				"failed read XDomain properties from %pUb\n",
+				xd->remote_uuid);
+		}
+		return;
+	}
+
+	xd->properties_retries = XDOMAIN_PROPERTIES_RETRIES;
+
+	mutex_lock(&xd->lock);
+
+	/* Only accept newer generation properties */
+	if (xd->properties && gen <= xd->property_block_gen) {
+		/*
+		 * On resume it is likely that the properties block is
+		 * not changed (unless the other end added or removed
+		 * services). However, we need to make sure the existing
+		 * DMA paths are restored properly.
+		 */
+		tb_xdomain_restore_paths(xd);
+		goto err_free_block;
+	}
+
+	dir = tb_property_parse_dir(block, ret);
+	if (!dir) {
+		dev_err(&xd->dev, "failed to parse XDomain properties\n");
+		goto err_free_block;
+	}
+
+	ret = populate_properties(xd, dir);
+	if (ret) {
+		dev_err(&xd->dev, "missing XDomain properties in response\n");
+		goto err_free_dir;
+	}
+
+	/* Release the existing one */
+	if (xd->properties) {
+		tb_property_free_dir(xd->properties);
+		update = true;
+	}
+
+	xd->properties = dir;
+	xd->property_block_gen = gen;
+
+	tb_xdomain_restore_paths(xd);
+
+	mutex_unlock(&xd->lock);
+
+	kfree(block);
+
+	/*
+	 * Now the device should be ready enough so we can add it to the
+	 * bus and let userspace know about it. If the device is already
+	 * registered, we notify the userspace that it has changed.
+	 */
+	if (!update) {
+		if (device_add(&xd->dev)) {
+			dev_err(&xd->dev, "failed to add XDomain device\n");
+			return;
+		}
+	} else {
+		kobject_uevent(&xd->dev.kobj, KOBJ_CHANGE);
+	}
+
+	enumerate_services(xd);
+	return;
+
+err_free_dir:
+	tb_property_free_dir(dir);
+err_free_block:
+	kfree(block);
+	mutex_unlock(&xd->lock);
+}
+
+static void tb_xdomain_properties_changed(struct work_struct *work)
+{
+	struct tb_xdomain *xd = container_of(work, typeof(*xd),
+					     properties_changed_work.work);
+	int ret;
+
+	ret = tb_xdp_properties_changed_request(xd->tb->ctl, xd->route,
+				xd->properties_changed_retries, xd->local_uuid);
+	if (ret) {
+		if (xd->properties_changed_retries-- > 0)
+			queue_delayed_work(xd->tb->wq,
+					   &xd->properties_changed_work,
+					   msecs_to_jiffies(1000));
+		return;
+	}
+
+	xd->properties_changed_retries = XDOMAIN_PROPERTIES_CHANGED_RETRIES;
+}
+
+static ssize_t device_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct tb_xdomain *xd = container_of(dev, struct tb_xdomain, dev);
+
+	return sprintf(buf, "%#x\n", xd->device);
+}
+static DEVICE_ATTR_RO(device);
+
+static ssize_t
+device_name_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct tb_xdomain *xd = container_of(dev, struct tb_xdomain, dev);
+	int ret;
+
+	if (mutex_lock_interruptible(&xd->lock))
+		return -ERESTARTSYS;
+	ret = sprintf(buf, "%s\n", xd->device_name ? xd->device_name : "");
+	mutex_unlock(&xd->lock);
+
+	return ret;
+}
+static DEVICE_ATTR_RO(device_name);
+
+static ssize_t vendor_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct tb_xdomain *xd = container_of(dev, struct tb_xdomain, dev);
+
+	return sprintf(buf, "%#x\n", xd->vendor);
+}
+static DEVICE_ATTR_RO(vendor);
+
+static ssize_t
+vendor_name_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct tb_xdomain *xd = container_of(dev, struct tb_xdomain, dev);
+	int ret;
+
+	if (mutex_lock_interruptible(&xd->lock))
+		return -ERESTARTSYS;
+	ret = sprintf(buf, "%s\n", xd->vendor_name ? xd->vendor_name : "");
+	mutex_unlock(&xd->lock);
+
+	return ret;
+}
+static DEVICE_ATTR_RO(vendor_name);
+
+static ssize_t unique_id_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct tb_xdomain *xd = container_of(dev, struct tb_xdomain, dev);
+
+	return sprintf(buf, "%pUb\n", xd->remote_uuid);
+}
+static DEVICE_ATTR_RO(unique_id);
+
+static struct attribute *xdomain_attrs[] = {
+	&dev_attr_device.attr,
+	&dev_attr_device_name.attr,
+	&dev_attr_unique_id.attr,
+	&dev_attr_vendor.attr,
+	&dev_attr_vendor_name.attr,
+	NULL,
+};
+
+static struct attribute_group xdomain_attr_group = {
+	.attrs = xdomain_attrs,
+};
+
+static const struct attribute_group *xdomain_attr_groups[] = {
+	&xdomain_attr_group,
+	NULL,
+};
+
+static void tb_xdomain_release(struct device *dev)
+{
+	struct tb_xdomain *xd = container_of(dev, struct tb_xdomain, dev);
+
+	put_device(xd->dev.parent);
+
+	tb_property_free_dir(xd->properties);
+	ida_destroy(&xd->service_ids);
+
+	kfree(xd->local_uuid);
+	kfree(xd->remote_uuid);
+	kfree(xd->device_name);
+	kfree(xd->vendor_name);
+	kfree(xd);
+}
+
+static void start_handshake(struct tb_xdomain *xd)
+{
+	xd->properties_retries = XDOMAIN_PROPERTIES_RETRIES;
+	xd->properties_changed_retries = XDOMAIN_PROPERTIES_CHANGED_RETRIES;
+
+	/* Start exchanging properties with the other host */
+	queue_delayed_work(xd->tb->wq, &xd->properties_changed_work,
+			   msecs_to_jiffies(100));
+	queue_delayed_work(xd->tb->wq, &xd->get_properties_work,
+			   msecs_to_jiffies(1000));
+}
+
+static void stop_handshake(struct tb_xdomain *xd)
+{
+	xd->properties_retries = 0;
+	xd->properties_changed_retries = 0;
+
+	cancel_delayed_work_sync(&xd->get_properties_work);
+	cancel_delayed_work_sync(&xd->properties_changed_work);
+}
+
+static int __maybe_unused tb_xdomain_suspend(struct device *dev)
+{
+	stop_handshake(tb_to_xdomain(dev));
+	return 0;
+}
+
+static int __maybe_unused tb_xdomain_resume(struct device *dev)
+{
+	struct tb_xdomain *xd = tb_to_xdomain(dev);
+
+	/*
+	 * Ask tb_xdomain_get_properties() restore any existing DMA
+	 * paths after properties are re-read.
+	 */
+	xd->resume = true;
+	start_handshake(xd);
+
+	return 0;
+}
+
+static const struct dev_pm_ops tb_xdomain_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(tb_xdomain_suspend, tb_xdomain_resume)
+};
+
+struct device_type tb_xdomain_type = {
+	.name = "thunderbolt_xdomain",
+	.release = tb_xdomain_release,
+	.pm = &tb_xdomain_pm_ops,
+};
+EXPORT_SYMBOL_GPL(tb_xdomain_type);
+
+/**
+ * tb_xdomain_alloc() - Allocate new XDomain object
+ * @tb: Domain where the XDomain belongs
+ * @parent: Parent device (the switch through the connection to the
+ *	    other domain is reached).
+ * @route: Route string used to reach the other domain
+ * @local_uuid: Our local domain UUID
+ * @remote_uuid: UUID of the other domain
+ *
+ * Allocates new XDomain structure and returns pointer to that. The
+ * object must be released by calling tb_xdomain_put().
+ */
+struct tb_xdomain *tb_xdomain_alloc(struct tb *tb, struct device *parent,
+				    u64 route, const uuid_t *local_uuid,
+				    const uuid_t *remote_uuid)
+{
+	struct tb_xdomain *xd;
+
+	xd = kzalloc(sizeof(*xd), GFP_KERNEL);
+	if (!xd)
+		return NULL;
+
+	xd->tb = tb;
+	xd->route = route;
+	ida_init(&xd->service_ids);
+	mutex_init(&xd->lock);
+	INIT_DELAYED_WORK(&xd->get_properties_work, tb_xdomain_get_properties);
+	INIT_DELAYED_WORK(&xd->properties_changed_work,
+			  tb_xdomain_properties_changed);
+
+	xd->local_uuid = kmemdup(local_uuid, sizeof(uuid_t), GFP_KERNEL);
+	if (!xd->local_uuid)
+		goto err_free;
+
+	xd->remote_uuid = kmemdup(remote_uuid, sizeof(uuid_t), GFP_KERNEL);
+	if (!xd->remote_uuid)
+		goto err_free_local_uuid;
+
+	device_initialize(&xd->dev);
+	xd->dev.parent = get_device(parent);
+	xd->dev.bus = &tb_bus_type;
+	xd->dev.type = &tb_xdomain_type;
+	xd->dev.groups = xdomain_attr_groups;
+	dev_set_name(&xd->dev, "%u-%llx", tb->index, route);
+
+	return xd;
+
+err_free_local_uuid:
+	kfree(xd->local_uuid);
+err_free:
+	kfree(xd);
+
+	return NULL;
+}
+
+/**
+ * tb_xdomain_add() - Add XDomain to the bus
+ * @xd: XDomain to add
+ *
+ * This function starts XDomain discovery protocol handshake and
+ * eventually adds the XDomain to the bus. After calling this function
+ * the caller needs to call tb_xdomain_remove() in order to remove and
+ * release the object regardless whether the handshake succeeded or not.
+ */
+void tb_xdomain_add(struct tb_xdomain *xd)
+{
+	/* Start exchanging properties with the other host */
+	start_handshake(xd);
+}
+
+static int unregister_service(struct device *dev, void *data)
+{
+	device_unregister(dev);
+	return 0;
+}
+
+/**
+ * tb_xdomain_remove() - Remove XDomain from the bus
+ * @xd: XDomain to remove
+ *
+ * This will stop all ongoing configuration work and remove the XDomain
+ * along with any services from the bus. When the last reference to @xd
+ * is released the object will be released as well.
+ */
+void tb_xdomain_remove(struct tb_xdomain *xd)
+{
+	stop_handshake(xd);
+
+	device_for_each_child_reverse(&xd->dev, xd, unregister_service);
+
+	if (!device_is_registered(&xd->dev))
+		put_device(&xd->dev);
+	else
+		device_unregister(&xd->dev);
+}
+
+/**
+ * tb_xdomain_enable_paths() - Enable DMA paths for XDomain connection
+ * @xd: XDomain connection
+ * @transmit_path: HopID of the transmit path the other end is using to
+ *		   send packets
+ * @transmit_ring: DMA ring used to receive packets from the other end
+ * @receive_path: HopID of the receive path the other end is using to
+ *		  receive packets
+ * @receive_ring: DMA ring used to send packets to the other end
+ *
+ * The function enables DMA paths accordingly so that after successful
+ * return the caller can send and receive packets using high-speed DMA
+ * path.
+ *
+ * Return: %0 in case of success and negative errno in case of error
+ */
+int tb_xdomain_enable_paths(struct tb_xdomain *xd, u16 transmit_path,
+			    u16 transmit_ring, u16 receive_path,
+			    u16 receive_ring)
+{
+	int ret;
+
+	mutex_lock(&xd->lock);
+
+	if (xd->transmit_path) {
+		ret = xd->transmit_path == transmit_path ? 0 : -EBUSY;
+		goto exit_unlock;
+	}
+
+	xd->transmit_path = transmit_path;
+	xd->transmit_ring = transmit_ring;
+	xd->receive_path = receive_path;
+	xd->receive_ring = receive_ring;
+
+	ret = tb_domain_approve_xdomain_paths(xd->tb, xd);
+
+exit_unlock:
+	mutex_unlock(&xd->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tb_xdomain_enable_paths);
+
+/**
+ * tb_xdomain_disable_paths() - Disable DMA paths for XDomain connection
+ * @xd: XDomain connection
+ *
+ * This does the opposite of tb_xdomain_enable_paths(). After call to
+ * this the caller is not expected to use the rings anymore.
+ *
+ * Return: %0 in case of success and negative errno in case of error
+ */
+int tb_xdomain_disable_paths(struct tb_xdomain *xd)
+{
+	int ret = 0;
+
+	mutex_lock(&xd->lock);
+	if (xd->transmit_path) {
+		xd->transmit_path = 0;
+		xd->transmit_ring = 0;
+		xd->receive_path = 0;
+		xd->receive_ring = 0;
+
+		ret = tb_domain_disconnect_xdomain_paths(xd->tb, xd);
+	}
+	mutex_unlock(&xd->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tb_xdomain_disable_paths);
+
+struct tb_xdomain_lookup {
+	const uuid_t *uuid;
+	u8 link;
+	u8 depth;
+};
+
+static struct tb_xdomain *switch_find_xdomain(struct tb_switch *sw,
+	const struct tb_xdomain_lookup *lookup)
+{
+	int i;
+
+	for (i = 1; i <= sw->config.max_port_number; i++) {
+		struct tb_port *port = &sw->ports[i];
+		struct tb_xdomain *xd;
+
+		if (tb_is_upstream_port(port))
+			continue;
+
+		if (port->xdomain) {
+			xd = port->xdomain;
+
+			if (lookup->uuid) {
+				if (uuid_equal(xd->remote_uuid, lookup->uuid))
+					return xd;
+			} else if (lookup->link == xd->link &&
+				   lookup->depth == xd->depth) {
+				return xd;
+			}
+		} else if (port->remote) {
+			xd = switch_find_xdomain(port->remote->sw, lookup);
+			if (xd)
+				return xd;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * tb_xdomain_find_by_uuid() - Find an XDomain by UUID
+ * @tb: Domain where the XDomain belongs to
+ * @uuid: UUID to look for
+ *
+ * Finds XDomain by walking through the Thunderbolt topology below @tb.
+ * The returned XDomain will have its reference count increased so the
+ * caller needs to call tb_xdomain_put() when it is done with the
+ * object.
+ *
+ * This will find all XDomains including the ones that are not yet added
+ * to the bus (handshake is still in progress).
+ *
+ * The caller needs to hold @tb->lock.
+ */
+struct tb_xdomain *tb_xdomain_find_by_uuid(struct tb *tb, const uuid_t *uuid)
+{
+	struct tb_xdomain_lookup lookup;
+	struct tb_xdomain *xd;
+
+	memset(&lookup, 0, sizeof(lookup));
+	lookup.uuid = uuid;
+
+	xd = switch_find_xdomain(tb->root_switch, &lookup);
+	if (xd) {
+		get_device(&xd->dev);
+		return xd;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(tb_xdomain_find_by_uuid);
+
+/**
+ * tb_xdomain_find_by_link_depth() - Find an XDomain by link and depth
+ * @tb: Domain where the XDomain belongs to
+ * @link: Root switch link number
+ * @depth: Depth in the link
+ *
+ * Finds XDomain by walking through the Thunderbolt topology below @tb.
+ * The returned XDomain will have its reference count increased so the
+ * caller needs to call tb_xdomain_put() when it is done with the
+ * object.
+ *
+ * This will find all XDomains including the ones that are not yet added
+ * to the bus (handshake is still in progress).
+ *
+ * The caller needs to hold @tb->lock.
+ */
+struct tb_xdomain *tb_xdomain_find_by_link_depth(struct tb *tb, u8 link,
+						 u8 depth)
+{
+	struct tb_xdomain_lookup lookup;
+	struct tb_xdomain *xd;
+
+	memset(&lookup, 0, sizeof(lookup));
+	lookup.link = link;
+	lookup.depth = depth;
+
+	xd = switch_find_xdomain(tb->root_switch, &lookup);
+	if (xd) {
+		get_device(&xd->dev);
+		return xd;
+	}
+
+	return NULL;
+}
+
+bool tb_xdomain_handle_request(struct tb *tb, enum tb_cfg_pkg_type type,
+			       const void *buf, size_t size)
+{
+	const struct tb_protocol_handler *handler, *tmp;
+	const struct tb_xdp_header *hdr = buf;
+	unsigned int length;
+	int ret = 0;
+
+	/* We expect the packet is at least size of the header */
+	length = hdr->xd_hdr.length_sn & TB_XDOMAIN_LENGTH_MASK;
+	if (length != size / 4 - sizeof(hdr->xd_hdr) / 4)
+		return true;
+	if (length < sizeof(*hdr) / 4 - sizeof(hdr->xd_hdr) / 4)
+		return true;
+
+	/*
+	 * Handle XDomain discovery protocol packets directly here. For
+	 * other protocols (based on their UUID) we call registered
+	 * handlers in turn.
+	 */
+	if (uuid_equal(&hdr->uuid, &tb_xdp_uuid)) {
+		if (type == TB_CFG_PKG_XDOMAIN_REQ) {
+			tb_xdp_schedule_request(tb, hdr, size);
+			return true;
+		}
+		return false;
+	}
+
+	mutex_lock(&xdomain_lock);
+	list_for_each_entry_safe(handler, tmp, &protocol_handlers, list) {
+		if (!uuid_equal(&hdr->uuid, handler->uuid))
+			continue;
+
+		mutex_unlock(&xdomain_lock);
+		ret = handler->callback(buf, size, handler->data);
+		mutex_lock(&xdomain_lock);
+
+		if (ret)
+			break;
+	}
+	mutex_unlock(&xdomain_lock);
+
+	return ret > 0;
+}
+
+static int rebuild_property_block(void)
+{
+	u32 *block, len;
+	int ret;
+
+	ret = tb_property_format_dir(xdomain_property_dir, NULL, 0);
+	if (ret < 0)
+		return ret;
+
+	len = ret;
+
+	block = kcalloc(len, sizeof(u32), GFP_KERNEL);
+	if (!block)
+		return -ENOMEM;
+
+	ret = tb_property_format_dir(xdomain_property_dir, block, len);
+	if (ret) {
+		kfree(block);
+		return ret;
+	}
+
+	kfree(xdomain_property_block);
+	xdomain_property_block = block;
+	xdomain_property_block_len = len;
+	xdomain_property_block_gen++;
+
+	return 0;
+}
+
+static int update_xdomain(struct device *dev, void *data)
+{
+	struct tb_xdomain *xd;
+
+	xd = tb_to_xdomain(dev);
+	if (xd) {
+		queue_delayed_work(xd->tb->wq, &xd->properties_changed_work,
+				   msecs_to_jiffies(50));
+	}
+
+	return 0;
+}
+
+static void update_all_xdomains(void)
+{
+	bus_for_each_dev(&tb_bus_type, NULL, NULL, update_xdomain);
+}
+
+static bool remove_directory(const char *key, const struct tb_property_dir *dir)
+{
+	struct tb_property *p;
+
+	p = tb_property_find(xdomain_property_dir, key,
+			     TB_PROPERTY_TYPE_DIRECTORY);
+	if (p && p->value.dir == dir) {
+		tb_property_remove(p);
+		return true;
+	}
+	return false;
+}
+
+/**
+ * tb_register_property_dir() - Register property directory to the host
+ * @key: Key (name) of the directory to add
+ * @dir: Directory to add
+ *
+ * Service drivers can use this function to add new property directory
+ * to the host available properties. The other connected hosts are
+ * notified so they can re-read properties of this host if they are
+ * interested.
+ *
+ * Return: %0 on success and negative errno on failure
+ */
+int tb_register_property_dir(const char *key, struct tb_property_dir *dir)
+{
+	int ret;
+
+	if (!key || strlen(key) > 8)
+		return -EINVAL;
+
+	mutex_lock(&xdomain_lock);
+	if (tb_property_find(xdomain_property_dir, key,
+			     TB_PROPERTY_TYPE_DIRECTORY)) {
+		ret = -EEXIST;
+		goto err_unlock;
+	}
+
+	ret = tb_property_add_dir(xdomain_property_dir, key, dir);
+	if (ret)
+		goto err_unlock;
+
+	ret = rebuild_property_block();
+	if (ret) {
+		remove_directory(key, dir);
+		goto err_unlock;
+	}
+
+	mutex_unlock(&xdomain_lock);
+	update_all_xdomains();
+	return 0;
+
+err_unlock:
+	mutex_unlock(&xdomain_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tb_register_property_dir);
+
+/**
+ * tb_unregister_property_dir() - Removes property directory from host
+ * @key: Key (name) of the directory
+ * @dir: Directory to remove
+ *
+ * This will remove the existing directory from this host and notify the
+ * connected hosts about the change.
+ */
+void tb_unregister_property_dir(const char *key, struct tb_property_dir *dir)
+{
+	int ret = 0;
+
+	mutex_lock(&xdomain_lock);
+	if (remove_directory(key, dir))
+		ret = rebuild_property_block();
+	mutex_unlock(&xdomain_lock);
+
+	if (!ret)
+		update_all_xdomains();
+}
+EXPORT_SYMBOL_GPL(tb_unregister_property_dir);
+
+int tb_xdomain_init(void)
+{
+	int ret;
+
+	xdomain_property_dir = tb_property_create_dir(NULL);
+	if (!xdomain_property_dir)
+		return -ENOMEM;
+
+	/*
+	 * Initialize standard set of properties without any service
+	 * directories. Those will be added by service drivers
+	 * themselves when they are loaded.
+	 */
+	tb_property_add_immediate(xdomain_property_dir, "vendorid",
+				  PCI_VENDOR_ID_INTEL);
+	tb_property_add_text(xdomain_property_dir, "vendorid", "Intel Corp.");
+	tb_property_add_immediate(xdomain_property_dir, "deviceid", 0x1);
+	tb_property_add_text(xdomain_property_dir, "deviceid",
+			     utsname()->nodename);
+	tb_property_add_immediate(xdomain_property_dir, "devicerv", 0x80000100);
+
+	ret = rebuild_property_block();
+	if (ret) {
+		tb_property_free_dir(xdomain_property_dir);
+		xdomain_property_dir = NULL;
+	}
+
+	return ret;
+}
+
+void tb_xdomain_exit(void)
+{
+	kfree(xdomain_property_block);
+	tb_property_free_dir(xdomain_property_dir);
+}