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>

1 files changed, 216 insertions, 2 deletions

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;
 	}