thunderbolt: Add support for Display Port tunnels

Display Port tunnels are somewhat more complex than PCIe tunnels as it
requires 3 tunnels (AUX Rx/Tx and Video). In addition we are not
supposed to create the tunnels immediately when a DP OUT is enumerated.
Instead we need to wait until we get hotplug event to that adapter port
or check if the port has HPD set before tunnels can be established. This
adds Display Port tunneling support to the software connection manager.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 273 insertions, 4 deletions

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)