thunderbolt: Add support for USB 3.x tunnels

USB4 added a capability to tunnel USB 3.x protocol over the USB4
fabric. USB4 device routers may include integrated SuperSpeed HUB or a
function or both. USB tunneling follows PCIe so that the tunnel is
created between the parent and the child router from USB3 downstream
adapter port to USB3 upstream adapter port over a single USB4 link.

This adds support for USB 3.x tunneling and also capability to discover
existing USB 3.x tunnels (for example created by connection manager in
boot firmware).

Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
Co-developed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20191217123345.31850-9-mika.westerberg@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 130 insertions, 24 deletions

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index e446624dd3e7..107cd232f486 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -111,6 +111,10 @@ static void tb_discover_tunnels(struct tb_switch *sw)
 			tunnel = tb_tunnel_discover_pci(tb, port);
 			break;
 
+		case TB_TYPE_USB3_DOWN:
+			tunnel = tb_tunnel_discover_usb3(tb, port);
+			break;
+
 		default:
 			break;
 		}
@@ -177,6 +181,118 @@ static int tb_enable_tmu(struct tb_switch *sw)
 	return tb_switch_tmu_enable(sw);
 }
 
+/**
+ * tb_find_unused_port() - return the first inactive port on @sw
+ * @sw: Switch to find the port on
+ * @type: Port type to look for
+ */
+static struct tb_port *tb_find_unused_port(struct tb_switch *sw,
+					   enum tb_port_type type)
+{
+	struct tb_port *port;
+
+	tb_switch_for_each_port(sw, port) {
+		if (tb_is_upstream_port(port))
+			continue;
+		if (port->config.type != type)
+			continue;
+		if (!port->cap_adap)
+			continue;
+		if (tb_port_is_enabled(port))
+			continue;
+		return port;
+	}
+	return NULL;
+}
+
+static struct tb_port *tb_find_usb3_down(struct tb_switch *sw,
+					const struct tb_port *port)
+{
+	struct tb_port *down;
+
+	down = usb4_switch_map_usb3_down(sw, port);
+	if (down) {
+		if (WARN_ON(!tb_port_is_usb3_down(down)))
+			goto out;
+		if (WARN_ON(tb_usb3_port_is_enabled(down)))
+			goto out;
+
+		return down;
+	}
+
+out:
+	return tb_find_unused_port(sw, TB_TYPE_USB3_DOWN);
+}
+
+static int tb_tunnel_usb3(struct tb *tb, struct tb_switch *sw)
+{
+	struct tb_switch *parent = tb_switch_parent(sw);
+	struct tb_port *up, *down, *port;
+	struct tb_cm *tcm = tb_priv(tb);
+	struct tb_tunnel *tunnel;
+
+	up = tb_switch_find_port(sw, TB_TYPE_USB3_UP);
+	if (!up)
+		return 0;
+
+	/*
+	 * Look up available down port. Since we are chaining it should
+	 * be found right above this switch.
+	 */
+	port = tb_port_at(tb_route(sw), parent);
+	down = tb_find_usb3_down(parent, port);
+	if (!down)
+		return 0;
+
+	if (tb_route(parent)) {
+		struct tb_port *parent_up;
+		/*
+		 * Check first that the parent switch has its upstream USB3
+		 * port enabled. Otherwise the chain is not complete and
+		 * there is no point setting up a new tunnel.
+		 */
+		parent_up = tb_switch_find_port(parent, TB_TYPE_USB3_UP);
+		if (!parent_up || !tb_port_is_enabled(parent_up))
+			return 0;
+	}
+
+	tunnel = tb_tunnel_alloc_usb3(tb, up, down);
+	if (!tunnel)
+		return -ENOMEM;
+
+	if (tb_tunnel_activate(tunnel)) {
+		tb_port_info(up,
+			     "USB3 tunnel activation failed, aborting\n");
+		tb_tunnel_free(tunnel);
+		return -EIO;
+	}
+
+	list_add_tail(&tunnel->list, &tcm->tunnel_list);
+	return 0;
+}
+
+static int tb_create_usb3_tunnels(struct tb_switch *sw)
+{
+	struct tb_port *port;
+	int ret;
+
+	if (tb_route(sw)) {
+		ret = tb_tunnel_usb3(sw->tb, sw);
+		if (ret)
+			return ret;
+	}
+
+	tb_switch_for_each_port(sw, port) {
+		if (!tb_port_has_remote(port))
+			continue;
+		ret = tb_create_usb3_tunnels(port->remote->sw);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static void tb_scan_port(struct tb_port *port);
 
 /**
@@ -279,6 +395,15 @@ static void tb_scan_port(struct tb_port *port)
 	if (tb_enable_tmu(sw))
 		tb_sw_warn(sw, "failed to enable TMU\n");
 
+	/*
+	 * Create USB 3.x tunnels only when the switch is plugged to the
+	 * domain. This is because we scan the domain also during discovery
+	 * and want to discover existing USB 3.x tunnels before we create
+	 * any new.
+	 */
+	if (tcm->hotplug_active && tb_tunnel_usb3(sw->tb, sw))
+		tb_sw_warn(sw, "USB3 tunnel creation failed\n");
+
 	tb_scan_switch(sw);
 }
 
@@ -360,30 +485,6 @@ static void tb_free_unplugged_children(struct tb_switch *sw)
 	}
 }
 
-/**
- * tb_find_unused_port() - return the first inactive port on @sw
- * @sw: Switch to find the port on
- * @type: Port type to look for
- */
-static struct tb_port *tb_find_unused_port(struct tb_switch *sw,
-					   enum tb_port_type type)
-{
-	struct tb_port *port;
-
-	tb_switch_for_each_port(sw, port) {
-		if (tb_is_upstream_port(port))
-			continue;
-		if (port->config.type != type)
-			continue;
-		if (port->cap_adap)
-			continue;
-		if (tb_port_is_enabled(port))
-			continue;
-		return port;
-	}
-	return NULL;
-}
-
 static struct tb_port *tb_find_pcie_down(struct tb_switch *sw,
 					 const struct tb_port *port)
 {
@@ -884,6 +985,11 @@ static int tb_start(struct tb *tb)
 	tb_scan_switch(tb->root_switch);
 	/* Find out tunnels created by the boot firmware */
 	tb_discover_tunnels(tb->root_switch);
+	/*
+	 * If the boot firmware did not create USB 3.x tunnels create them
+	 * now for the whole topology.
+	 */
+	tb_create_usb3_tunnels(tb->root_switch);
 	/* Add DP IN resources for the root switch */
 	tb_add_dp_resources(tb->root_switch);
 	/* Make the discovered switches available to the userspace */