6 files changed, 554 insertions, 25 deletions

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 9462e6982061..1de1afa24182 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -747,6 +747,10 @@ bool tb_port_is_enabled(struct tb_port *port)
 	case TB_TYPE_PCIE_DOWN:
 		return tb_pci_port_is_enabled(port);
 
+	case TB_TYPE_DP_HDMI_IN:
+	case TB_TYPE_DP_HDMI_OUT:
+		return tb_dp_port_is_enabled(port);
+
 	default:
 		return false;
 	}
@@ -779,6 +783,113 @@ int tb_pci_port_enable(struct tb_port *port, bool enable)
 	return tb_port_write(port, &word, TB_CFG_PORT, port->cap_adap, 1);
 }
 
+/**
+ * tb_dp_port_hpd_is_active() - Is HPD already active
+ * @port: DP out port to check
+ *
+ * Checks if the DP OUT adapter port has HDP bit already set.
+ */
+int tb_dp_port_hpd_is_active(struct tb_port *port)
+{
+	u32 data;
+	int ret;
+
+	ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap + 2, 1);
+	if (ret)
+		return ret;
+
+	return !!(data & TB_DP_HDP);
+}
+
+/**
+ * tb_dp_port_hpd_clear() - Clear HPD from DP IN port
+ * @port: Port to clear HPD
+ *
+ * If the DP IN port has HDP set, this function can be used to clear it.
+ */
+int tb_dp_port_hpd_clear(struct tb_port *port)
+{
+	u32 data;
+	int ret;
+
+	ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap + 3, 1);
+	if (ret)
+		return ret;
+
+	data |= TB_DP_HPDC;
+	return tb_port_write(port, &data, TB_CFG_PORT, port->cap_adap + 3, 1);
+}
+
+/**
+ * tb_dp_port_set_hops() - Set video/aux Hop IDs for DP port
+ * @port: DP IN/OUT port to set hops
+ * @video: Video Hop ID
+ * @aux_tx: AUX TX Hop ID
+ * @aux_rx: AUX RX Hop ID
+ *
+ * Programs specified Hop IDs for DP IN/OUT port.
+ */
+int tb_dp_port_set_hops(struct tb_port *port, unsigned int video,
+			unsigned int aux_tx, unsigned int aux_rx)
+{
+	u32 data[2];
+	int ret;
+
+	ret = tb_port_read(port, data, TB_CFG_PORT, port->cap_adap,
+			   ARRAY_SIZE(data));
+	if (ret)
+		return ret;
+
+	data[0] &= ~TB_DP_VIDEO_HOPID_MASK;
+	data[1] &= ~(TB_DP_AUX_RX_HOPID_MASK | TB_DP_AUX_TX_HOPID_MASK);
+
+	data[0] |= (video << TB_DP_VIDEO_HOPID_SHIFT) & TB_DP_VIDEO_HOPID_MASK;
+	data[1] |= aux_tx & TB_DP_AUX_TX_HOPID_MASK;
+	data[1] |= (aux_rx << TB_DP_AUX_RX_HOPID_SHIFT) & TB_DP_AUX_RX_HOPID_MASK;
+
+	return tb_port_write(port, data, TB_CFG_PORT, port->cap_adap,
+			     ARRAY_SIZE(data));
+}
+
+/**
+ * tb_dp_port_is_enabled() - Is DP adapter port enabled
+ * @port: DP adapter port to check
+ */
+bool tb_dp_port_is_enabled(struct tb_port *port)
+{
+	u32 data;
+
+	if (tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap, 1))
+		return false;
+
+	return !!(data & (TB_DP_VIDEO_EN | TB_DP_AUX_EN));
+}
+
+/**
+ * tb_dp_port_enable() - Enables/disables DP paths of a port
+ * @port: DP IN/OUT port
+ * @enable: Enable/disable DP path
+ *
+ * Once Hop IDs are programmed DP paths can be enabled or disabled by
+ * calling this function.
+ */
+int tb_dp_port_enable(struct tb_port *port, bool enable)
+{
+	u32 data;
+	int ret;
+
+	ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap, 1);
+	if (ret)
+		return ret;
+
+	if (enable)
+		data |= TB_DP_VIDEO_EN | TB_DP_AUX_EN;
+	else
+		data &= ~(TB_DP_VIDEO_EN | TB_DP_AUX_EN);
+
+	return tb_port_write(port, &data, TB_CFG_PORT, port->cap_adap, 1);
+}
+
 /* switch utility functions */
 
 static void tb_dump_switch(struct tb *tb, struct tb_regs_switch_header *sw)
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 903922a16d64..c5e96e7ac37a 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -28,6 +28,32 @@ struct tb_cm {
 	bool hotplug_active;
 };
 
+struct tb_hotplug_event {
+	struct work_struct work;
+	struct tb *tb;
+	u64 route;
+	u8 port;
+	bool unplug;
+};
+
+static void tb_handle_hotplug(struct work_struct *work);
+
+static void tb_queue_hotplug(struct tb *tb, u64 route, u8 port, bool unplug)
+{
+	struct tb_hotplug_event *ev;
+
+	ev = kmalloc(sizeof(*ev), GFP_KERNEL);
+	if (!ev)
+		return;
+
+	ev->tb = tb;
+	ev->route = route;
+	ev->port = port;
+	ev->unplug = unplug;
+	INIT_WORK(&ev->work, tb_handle_hotplug);
+	queue_work(tb->wq, &ev->work);
+}
+
 /* enumeration & hot plug handling */
 
 static void tb_discover_tunnels(struct tb_switch *sw)
@@ -42,6 +68,10 @@ static void tb_discover_tunnels(struct tb_switch *sw)
 
 		port = &sw->ports[i];
 		switch (port->config.type) {
+		case TB_TYPE_DP_HDMI_IN:
+			tunnel = tb_tunnel_discover_dp(tb, port);
+			break;
+
 		case TB_TYPE_PCIE_DOWN:
 			tunnel = tb_tunnel_discover_pci(tb, port);
 			break;
@@ -50,16 +80,19 @@ static void tb_discover_tunnels(struct tb_switch *sw)
 			break;
 		}
 
-		if (tunnel) {
+		if (!tunnel)
+			continue;
+
+		if (tb_tunnel_is_pci(tunnel)) {
 			struct tb_switch *parent = tunnel->dst_port->sw;
 
 			while (parent != tunnel->src_port->sw) {
 				parent->boot = true;
 				parent = tb_switch_parent(parent);
 			}
-
-			list_add_tail(&tunnel->list, &tcm->tunnel_list);
 		}
+
+		list_add_tail(&tunnel->list, &tcm->tunnel_list);
 	}
 
 	for (i = 1; i <= sw->config.max_port_number; i++) {
@@ -91,6 +124,15 @@ static void tb_scan_port(struct tb_port *port)
 
 	if (tb_is_upstream_port(port))
 		return;
+
+	if (tb_port_is_dpout(port) && tb_dp_port_hpd_is_active(port) == 1 &&
+	    !tb_dp_port_is_enabled(port)) {
+		tb_port_dbg(port, "DP adapter HPD set, queuing hotplug\n");
+		tb_queue_hotplug(port->sw->tb, tb_route(port->sw), port->port,
+				 false);
+		return;
+	}
+
 	if (port->config.type != TB_TYPE_PORT)
 		return;
 	if (port->dual_link_port && port->link_nr)
@@ -139,6 +181,26 @@ static void tb_scan_port(struct tb_port *port)
 	tb_scan_switch(sw);
 }
 
+static int tb_free_tunnel(struct tb *tb, enum tb_tunnel_type type,
+			  struct tb_port *src_port, struct tb_port *dst_port)
+{
+	struct tb_cm *tcm = tb_priv(tb);
+	struct tb_tunnel *tunnel;
+
+	list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
+		if (tunnel->type == type &&
+		    ((src_port && src_port == tunnel->src_port) ||
+		     (dst_port && dst_port == tunnel->dst_port))) {
+			tb_tunnel_deactivate(tunnel);
+			list_del(&tunnel->list);
+			tb_tunnel_free(tunnel);
+			return 0;
+		}
+	}
+
+	return -ENODEV;
+}
+
 /**
  * tb_free_invalid_tunnels() - destroy tunnels of devices that have gone away
  */
@@ -257,6 +319,44 @@ out:
 	return tb_find_unused_port(sw, TB_TYPE_PCIE_DOWN);
 }
 
+static int tb_tunnel_dp(struct tb *tb, struct tb_port *out)
+{
+	struct tb_cm *tcm = tb_priv(tb);
+	struct tb_switch *sw = out->sw;
+	struct tb_tunnel *tunnel;
+	struct tb_port *in;
+
+	if (tb_port_is_enabled(out))
+		return 0;
+
+	do {
+		sw = tb_to_switch(sw->dev.parent);
+		if (!sw)
+			return 0;
+		in = tb_find_unused_port(sw, TB_TYPE_DP_HDMI_IN);
+	} while (!in);
+
+	tunnel = tb_tunnel_alloc_dp(tb, in, out);
+	if (!tunnel) {
+		tb_port_dbg(out, "DP tunnel allocation failed\n");
+		return -ENOMEM;
+	}
+
+	if (tb_tunnel_activate(tunnel)) {
+		tb_port_info(out, "DP tunnel activation failed, aborting\n");
+		tb_tunnel_free(tunnel);
+		return -EIO;
+	}
+
+	list_add_tail(&tunnel->list, &tcm->tunnel_list);
+	return 0;
+}
+
+static void tb_teardown_dp(struct tb *tb, struct tb_port *out)
+{
+	tb_free_tunnel(tb, TB_TUNNEL_DP, NULL, out);
+}
+
 static int tb_tunnel_pci(struct tb *tb, struct tb_switch *sw)
 {
 	struct tb_port *up, *down, *port;
@@ -295,14 +395,6 @@ static int tb_tunnel_pci(struct tb *tb, struct tb_switch *sw)
 
 /* hotplug handling */
 
-struct tb_hotplug_event {
-	struct work_struct work;
-	struct tb *tb;
-	u64 route;
-	u8 port;
-	bool unplug;
-};
-
 /**
  * tb_handle_hotplug() - handle hotplug event
  *
@@ -347,6 +439,8 @@ static void tb_handle_hotplug(struct work_struct *work)
 			port->remote = NULL;
 			if (port->dual_link_port)
 				port->dual_link_port->remote = NULL;
+		} else if (tb_port_is_dpout(port)) {
+			tb_teardown_dp(tb, port);
 		} else {
 			tb_port_info(port,
 				     "got unplug event for disconnected port, ignoring\n");
@@ -360,6 +454,8 @@ static void tb_handle_hotplug(struct work_struct *work)
 			tb_scan_port(port);
 			if (!port->remote)
 				tb_port_info(port, "hotplug: no switch found\n");
+		} else if (tb_port_is_dpout(port)) {
+			tb_tunnel_dp(tb, port);
 		}
 	}
 
@@ -379,7 +475,6 @@ static void tb_handle_event(struct tb *tb, enum tb_cfg_pkg_type type,
 			    const void *buf, size_t size)
 {
 	const struct cfg_event_pkg *pkg = buf;
-	struct tb_hotplug_event *ev;
 	u64 route;
 
 	if (type != TB_CFG_PKG_EVENT) {
@@ -395,15 +490,7 @@ static void tb_handle_event(struct tb *tb, enum tb_cfg_pkg_type type,
 			pkg->port);
 	}
 
-	ev = kmalloc(sizeof(*ev), GFP_KERNEL);
-	if (!ev)
-		return;
-	INIT_WORK(&ev->work, tb_handle_hotplug);
-	ev->tb = tb;
-	ev->route = route;
-	ev->port = pkg->port;
-	ev->unplug = pkg->unplug;
-	queue_work(tb->wq, &ev->work);
+	tb_queue_hotplug(tb, route, pkg->port, pkg->unplug);
 }
 
 static void tb_stop(struct tb *tb)
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index e6040c9f68fa..56eed0bc3c2b 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -365,6 +365,16 @@ static inline bool tb_port_is_pcie_up(const struct tb_port *port)
 	return port && port->config.type == TB_TYPE_PCIE_UP;
 }
 
+static inline bool tb_port_is_dpin(const struct tb_port *port)
+{
+	return port && port->config.type == TB_TYPE_DP_HDMI_IN;
+}
+
+static inline bool tb_port_is_dpout(const struct tb_port *port)
+{
+	return port && port->config.type == TB_TYPE_DP_HDMI_OUT;
+}
+
 static inline int tb_sw_read(struct tb_switch *sw, void *buffer,
 			     enum tb_cfg_space space, u32 offset, u32 length)
 {
@@ -581,6 +591,13 @@ bool tb_port_is_enabled(struct tb_port *port);
 bool tb_pci_port_is_enabled(struct tb_port *port);
 int tb_pci_port_enable(struct tb_port *port, bool enable);
 
+int tb_dp_port_hpd_is_active(struct tb_port *port);
+int tb_dp_port_hpd_clear(struct tb_port *port);
+int tb_dp_port_set_hops(struct tb_port *port, unsigned int video,
+			unsigned int aux_tx, unsigned int aux_rx);
+bool tb_dp_port_is_enabled(struct tb_port *port);
+int tb_dp_port_enable(struct tb_port *port, bool enable);
+
 struct tb_path *tb_path_discover(struct tb_port *src, int src_hopid,
 				 struct tb_port *dst, int dst_hopid,
 				 struct tb_port **last, const char *name);
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 74c0f4a5606d..3ce705184e2c 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -213,6 +213,28 @@ struct tb_regs_port_header {
 
 /* DWORD 4 */
 #define TB_PORT_NFC_CREDITS_MASK	GENMASK(19, 0)
+#define TB_PORT_MAX_CREDITS_SHIFT	20
+#define TB_PORT_MAX_CREDITS_MASK	GENMASK(26, 20)
+
+/* Display Port adapter registers */
+
+/* DWORD 0 */
+#define TB_DP_VIDEO_HOPID_SHIFT		16
+#define TB_DP_VIDEO_HOPID_MASK		GENMASK(26, 16)
+#define TB_DP_AUX_EN			BIT(30)
+#define TB_DP_VIDEO_EN			BIT(31)
+/* DWORD 1 */
+#define TB_DP_AUX_TX_HOPID_MASK		GENMASK(10, 0)
+#define TB_DP_AUX_RX_HOPID_SHIFT	11
+#define TB_DP_AUX_RX_HOPID_MASK		GENMASK(21, 11)
+/* DWORD 2 */
+#define TB_DP_HDP			BIT(6)
+/* DWORD 3 */
+#define TB_DP_HPDC			BIT(9)
+/* DWORD 4 */
+#define TB_DP_LOCAL_CAP			0x4
+/* DWORD 5 */
+#define TB_DP_REMOTE_CAP		0x5
 
 /* PCIe adapter registers */
 
diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index 71c712300326..21d3393c6e9c 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -18,14 +18,26 @@
 #define TB_PCI_PATH_DOWN		0
 #define TB_PCI_PATH_UP			1
 
+/* DP adapters use HopID 8 for AUX and 9 for Video */
+#define TB_DP_AUX_TX_HOPID		8
+#define TB_DP_AUX_RX_HOPID		8
+#define TB_DP_VIDEO_HOPID		9
+
+#define TB_DP_VIDEO_PATH_OUT		0
+#define TB_DP_AUX_PATH_OUT		1
+#define TB_DP_AUX_PATH_IN		2
+
+static const char * const tb_tunnel_names[] = { "PCI", "DP" };
+
 #define __TB_TUNNEL_PRINT(level, tunnel, fmt, arg...)                   \
 	do {                                                            \
 		struct tb_tunnel *__tunnel = (tunnel);                  \
-		level(__tunnel->tb, "%llx:%x <-> %llx:%x (PCI): " fmt,  \
+		level(__tunnel->tb, "%llx:%x <-> %llx:%x (%s): " fmt,   \
 		      tb_route(__tunnel->src_port->sw),                 \
 		      __tunnel->src_port->port,                         \
 		      tb_route(__tunnel->dst_port->sw),                 \
 		      __tunnel->dst_port->port,                         \
+		      tb_tunnel_names[__tunnel->type],			\
 		      ## arg);                                          \
 	} while (0)
 
@@ -38,7 +50,8 @@
 #define tb_tunnel_dbg(tunnel, fmt, arg...) \
 	__TB_TUNNEL_PRINT(tb_dbg, tunnel, fmt, ##arg)
 
-static struct tb_tunnel *tb_tunnel_alloc(struct tb *tb, size_t npaths)
+static struct tb_tunnel *tb_tunnel_alloc(struct tb *tb, size_t npaths,
+					 enum tb_tunnel_type type)
 {
 	struct tb_tunnel *tunnel;
 
@@ -55,6 +68,7 @@ static struct tb_tunnel *tb_tunnel_alloc(struct tb *tb, size_t npaths)
 	INIT_LIST_HEAD(&tunnel->list);
 	tunnel->tb = tb;
 	tunnel->npaths = npaths;
+	tunnel->type = type;
 
 	return tunnel;
 }
@@ -104,7 +118,7 @@ struct tb_tunnel *tb_tunnel_discover_pci(struct tb *tb, struct tb_port *down)
 	if (!tb_pci_port_is_enabled(down))
 		return NULL;
 
-	tunnel = tb_tunnel_alloc(tb, 2);
+	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);
 	if (!tunnel)
 		return NULL;
 
@@ -179,7 +193,7 @@ struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
 	struct tb_tunnel *tunnel;
 	struct tb_path *path;
 
-	tunnel = tb_tunnel_alloc(tb, 2);
+	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);
 	if (!tunnel)
 		return NULL;
 
@@ -208,6 +222,255 @@ struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
 	return tunnel;
 }
 
+static int tb_dp_xchg_caps(struct tb_tunnel *tunnel)
+{
+	struct tb_port *out = tunnel->dst_port;
+	struct tb_port *in = tunnel->src_port;
+	u32 in_dp_cap, out_dp_cap;
+	int ret;
+
+	/*
+	 * Copy DP_LOCAL_CAP register to DP_REMOTE_CAP register for
+	 * newer generation hardware.
+	 */
+	if (in->sw->generation < 2 || out->sw->generation < 2)
+		return 0;
+
+	/* Read both DP_LOCAL_CAP registers */
+	ret = tb_port_read(in, &in_dp_cap, TB_CFG_PORT,
+			   in->cap_adap + TB_DP_LOCAL_CAP, 1);
+	if (ret)
+		return ret;
+
+	ret = tb_port_read(out, &out_dp_cap, TB_CFG_PORT,
+			   out->cap_adap + TB_DP_LOCAL_CAP, 1);
+	if (ret)
+		return ret;
+
+	/* Write IN local caps to OUT remote caps */
+	ret = tb_port_write(out, &in_dp_cap, TB_CFG_PORT,
+			    out->cap_adap + TB_DP_REMOTE_CAP, 1);
+	if (ret)
+		return ret;
+
+	return tb_port_write(in, &out_dp_cap, TB_CFG_PORT,
+			     in->cap_adap + TB_DP_REMOTE_CAP, 1);
+}
+
+static int tb_dp_activate(struct tb_tunnel *tunnel, bool active)
+{
+	int ret;
+
+	if (active) {
+		struct tb_path **paths;
+		int last;
+
+		paths = tunnel->paths;
+		last = paths[TB_DP_VIDEO_PATH_OUT]->path_length - 1;
+
+		tb_dp_port_set_hops(tunnel->src_port,
+			paths[TB_DP_VIDEO_PATH_OUT]->hops[0].in_hop_index,
+			paths[TB_DP_AUX_PATH_OUT]->hops[0].in_hop_index,
+			paths[TB_DP_AUX_PATH_IN]->hops[last].next_hop_index);
+
+		tb_dp_port_set_hops(tunnel->dst_port,
+			paths[TB_DP_VIDEO_PATH_OUT]->hops[last].next_hop_index,
+			paths[TB_DP_AUX_PATH_IN]->hops[0].in_hop_index,
+			paths[TB_DP_AUX_PATH_OUT]->hops[last].next_hop_index);
+	} else {
+		tb_dp_port_hpd_clear(tunnel->src_port);
+		tb_dp_port_set_hops(tunnel->src_port, 0, 0, 0);
+		if (tb_port_is_dpout(tunnel->dst_port))
+			tb_dp_port_set_hops(tunnel->dst_port, 0, 0, 0);
+	}
+
+	ret = tb_dp_port_enable(tunnel->src_port, active);
+	if (ret)
+		return ret;
+
+	if (tb_port_is_dpout(tunnel->dst_port))
+		return tb_dp_port_enable(tunnel->dst_port, active);
+
+	return 0;
+}
+
+static void tb_dp_init_aux_path(struct tb_path *path)
+{
+	int i;
+
+	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
+	path->egress_shared_buffer = TB_PATH_NONE;
+	path->ingress_fc_enable = TB_PATH_ALL;
+	path->ingress_shared_buffer = TB_PATH_NONE;
+	path->priority = 2;
+	path->weight = 1;
+
+	for (i = 0; i < path->path_length; i++)
+		path->hops[i].initial_credits = 1;
+}
+
+static void tb_dp_init_video_path(struct tb_path *path, bool discover)
+{
+	u32 nfc_credits = path->hops[0].in_port->config.nfc_credits;
+
+	path->egress_fc_enable = TB_PATH_NONE;
+	path->egress_shared_buffer = TB_PATH_NONE;
+	path->ingress_fc_enable = TB_PATH_NONE;
+	path->ingress_shared_buffer = TB_PATH_NONE;
+	path->priority = 1;
+	path->weight = 1;
+
+	if (discover) {
+		path->nfc_credits = nfc_credits & TB_PORT_NFC_CREDITS_MASK;
+	} else {
+		u32 max_credits;
+
+		max_credits = (nfc_credits & TB_PORT_MAX_CREDITS_MASK) >>
+			TB_PORT_MAX_CREDITS_SHIFT;
+		/* Leave some credits for AUX path */
+		path->nfc_credits = min(max_credits - 2, 12U);
+	}
+}
+
+/**
+ * tb_tunnel_discover_dp() - Discover existing Display Port tunnels
+ * @tb: Pointer to the domain structure
+ * @in: DP in adapter
+ *
+ * If @in adapter is active, follows the tunnel to the DP out adapter
+ * and back. Returns the discovered tunnel or %NULL if there was no
+ * tunnel.
+ *
+ * Return: DP tunnel or %NULL if no tunnel found.
+ */
+struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in)
+{
+	struct tb_tunnel *tunnel;
+	struct tb_port *port;
+	struct tb_path *path;
+
+	if (!tb_dp_port_is_enabled(in))
+		return NULL;
+
+	tunnel = tb_tunnel_alloc(tb, 3, TB_TUNNEL_DP);
+	if (!tunnel)
+		return NULL;
+
+	tunnel->init = tb_dp_xchg_caps;
+	tunnel->activate = tb_dp_activate;
+	tunnel->src_port = in;
+
+	path = tb_path_discover(in, TB_DP_VIDEO_HOPID, NULL, -1,
+				&tunnel->dst_port, "Video");
+	if (!path) {
+		/* Just disable the DP IN port */
+		tb_dp_port_enable(in, false);
+		goto err_free;
+	}
+	tunnel->paths[TB_DP_VIDEO_PATH_OUT] = path;
+	tb_dp_init_video_path(tunnel->paths[TB_DP_VIDEO_PATH_OUT], true);
+
+	path = tb_path_discover(in, TB_DP_AUX_TX_HOPID, NULL, -1, NULL, "AUX TX");
+	if (!path)
+		goto err_deactivate;
+	tunnel->paths[TB_DP_AUX_PATH_OUT] = path;
+	tb_dp_init_aux_path(tunnel->paths[TB_DP_AUX_PATH_OUT]);
+
+	path = tb_path_discover(tunnel->dst_port, -1, in, TB_DP_AUX_RX_HOPID,
+				&port, "AUX RX");
+	if (!path)
+		goto err_deactivate;
+	tunnel->paths[TB_DP_AUX_PATH_IN] = path;
+	tb_dp_init_aux_path(tunnel->paths[TB_DP_AUX_PATH_IN]);
+
+	/* Validate that the tunnel is complete */
+	if (!tb_port_is_dpout(tunnel->dst_port)) {
+		tb_port_warn(in, "path does not end on a DP adapter, cleaning up\n");
+		goto err_deactivate;
+	}
+
+	if (!tb_dp_port_is_enabled(tunnel->dst_port))
+		goto err_deactivate;
+
+	if (!tb_dp_port_hpd_is_active(tunnel->dst_port))
+		goto err_deactivate;
+
+	if (port != tunnel->src_port) {
+		tb_tunnel_warn(tunnel, "path is not complete, cleaning up\n");
+		goto err_deactivate;
+	}
+
+	tb_tunnel_dbg(tunnel, "discovered\n");
+	return tunnel;
+
+err_deactivate:
+	tb_tunnel_deactivate(tunnel);
+err_free:
+	tb_tunnel_free(tunnel);
+
+	return NULL;
+}
+
+/**
+ * tb_tunnel_alloc_dp() - allocate a Display Port tunnel
+ * @tb: Pointer to the domain structure
+ * @in: DP in adapter port
+ * @out: DP out adapter port
+ *
+ * Allocates a tunnel between @in and @out that is capable of tunneling
+ * Display Port traffic.
+ *
+ * Return: Returns a tb_tunnel on success or NULL on failure.
+ */
+struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,
+				     struct tb_port *out)
+{
+	struct tb_tunnel *tunnel;
+	struct tb_path **paths;
+	struct tb_path *path;
+
+	if (WARN_ON(!in->cap_adap || !out->cap_adap))
+		return NULL;
+
+	tunnel = tb_tunnel_alloc(tb, 3, TB_TUNNEL_DP);
+	if (!tunnel)
+		return NULL;
+
+	tunnel->init = tb_dp_xchg_caps;
+	tunnel->activate = tb_dp_activate;
+	tunnel->src_port = in;
+	tunnel->dst_port = out;
+
+	paths = tunnel->paths;
+
+	path = tb_path_alloc(tb, in, TB_DP_VIDEO_HOPID, out, TB_DP_VIDEO_HOPID,
+			     1, "Video");
+	if (!path)
+		goto err_free;
+	tb_dp_init_video_path(path, false);
+	paths[TB_DP_VIDEO_PATH_OUT] = path;
+
+	path = tb_path_alloc(tb, in, TB_DP_AUX_TX_HOPID, out,
+			     TB_DP_AUX_TX_HOPID, 1, "AUX TX");
+	if (!path)
+		goto err_free;
+	tb_dp_init_aux_path(path);
+	paths[TB_DP_AUX_PATH_OUT] = path;
+
+	path = tb_path_alloc(tb, out, TB_DP_AUX_RX_HOPID, in,
+			     TB_DP_AUX_RX_HOPID, 1, "AUX RX");
+	if (!path)
+		goto err_free;
+	tb_dp_init_aux_path(path);
+	paths[TB_DP_AUX_PATH_IN] = path;
+
+	return tunnel;
+
+err_free:
+	tb_tunnel_free(tunnel);
+	return NULL;
+}
+
 /**
  * tb_tunnel_free() - free a tunnel
  * @tunnel: Tunnel to be freed
@@ -278,6 +541,12 @@ int tb_tunnel_restart(struct tb_tunnel *tunnel)
 		}
 	}
 
+	if (tunnel->init) {
+		res = tunnel->init(tunnel);
+		if (res)
+			return res;
+	}
+
 	for (i = 0; i < tunnel->npaths; i++) {
 		res = tb_path_activate(tunnel->paths[i]);
 		if (res)
diff --git a/drivers/thunderbolt/tunnel.h b/drivers/thunderbolt/tunnel.h
index 07bf587bed80..0373779f43ba 100644
--- a/drivers/thunderbolt/tunnel.h
+++ b/drivers/thunderbolt/tunnel.h
@@ -11,6 +11,11 @@
 
 #include "tb.h"
 
+enum tb_tunnel_type {
+	TB_TUNNEL_PCI,
+	TB_TUNNEL_DP,
+};
+
 /**
  * struct tb_tunnel - Tunnel between two ports
  * @tb: Pointer to the domain
@@ -19,8 +24,10 @@
  *	      tunnels may be %NULL or null adapter port instead.
  * @paths: All paths required by the tunnel
  * @npaths: Number of paths in @paths
+ * @init: Optional tunnel specific initialization
  * @activate: Optional tunnel specific activation/deactivation
  * @list: Tunnels are linked using this field
+ * @type: Type of the tunnel
  */
 struct tb_tunnel {
 	struct tb *tb;
@@ -28,18 +35,34 @@ struct tb_tunnel {
 	struct tb_port *dst_port;
 	struct tb_path **paths;
 	size_t npaths;
+	int (*init)(struct tb_tunnel *tunnel);
 	int (*activate)(struct tb_tunnel *tunnel, bool activate);
 	struct list_head list;
+	enum tb_tunnel_type type;
 };
 
 struct tb_tunnel *tb_tunnel_discover_pci(struct tb *tb, struct tb_port *down);
 struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
 				      struct tb_port *down);
+struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in);
+struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,
+				     struct tb_port *out);
+
 void tb_tunnel_free(struct tb_tunnel *tunnel);
 int tb_tunnel_activate(struct tb_tunnel *tunnel);
 int tb_tunnel_restart(struct tb_tunnel *tunnel);
 void tb_tunnel_deactivate(struct tb_tunnel *tunnel);
 bool tb_tunnel_is_invalid(struct tb_tunnel *tunnel);
 
+static inline bool tb_tunnel_is_pci(const struct tb_tunnel *tunnel)
+{
+	return tunnel->type == TB_TUNNEL_PCI;
+}
+
+static inline bool tb_tunnel_is_dp(const struct tb_tunnel *tunnel)
+{
+	return tunnel->type == TB_TUNNEL_DP;
+}
+
 #endif