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, 157 insertions, 1 deletions

diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index 21d266a76b7d..dbe90bcf4ad4 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -19,6 +19,12 @@
 #define TB_PCI_PATH_DOWN		0
 #define TB_PCI_PATH_UP			1
 
+/* USB3 adapters use always HopID of 8 for both directions */
+#define TB_USB3_HOPID			8
+
+#define TB_USB3_PATH_DOWN		0
+#define TB_USB3_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
@@ -31,7 +37,7 @@
 #define TB_DMA_PATH_OUT			0
 #define TB_DMA_PATH_IN			1
 
-static const char * const tb_tunnel_names[] = { "PCI", "DP", "DMA" };
+static const char * const tb_tunnel_names[] = { "PCI", "DP", "DMA", "USB3" };
 
 #define __TB_TUNNEL_PRINT(level, tunnel, fmt, arg...)                   \
 	do {                                                            \
@@ -848,6 +854,156 @@ struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
 	return tunnel;
 }
 
+static int tb_usb3_activate(struct tb_tunnel *tunnel, bool activate)
+{
+	int res;
+
+	res = tb_usb3_port_enable(tunnel->src_port, activate);
+	if (res)
+		return res;
+
+	if (tb_port_is_usb3_up(tunnel->dst_port))
+		return tb_usb3_port_enable(tunnel->dst_port, activate);
+
+	return 0;
+}
+
+static void tb_usb3_init_path(struct tb_path *path)
+{
+	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 = 3;
+	path->weight = 3;
+	path->drop_packages = 0;
+	path->nfc_credits = 0;
+	path->hops[0].initial_credits = 7;
+	path->hops[1].initial_credits =
+		tb_initial_credits(path->hops[1].in_port->sw);
+}
+
+/**
+ * tb_tunnel_discover_usb3() - Discover existing USB3 tunnels
+ * @tb: Pointer to the domain structure
+ * @down: USB3 downstream adapter
+ *
+ * If @down adapter is active, follows the tunnel to the USB3 upstream
+ * adapter and back. Returns the discovered tunnel or %NULL if there was
+ * no tunnel.
+ */
+struct tb_tunnel *tb_tunnel_discover_usb3(struct tb *tb, struct tb_port *down)
+{
+	struct tb_tunnel *tunnel;
+	struct tb_path *path;
+
+	if (!tb_usb3_port_is_enabled(down))
+		return NULL;
+
+	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_USB3);
+	if (!tunnel)
+		return NULL;
+
+	tunnel->activate = tb_usb3_activate;
+	tunnel->src_port = down;
+
+	/*
+	 * Discover both paths even if they are not complete. We will
+	 * clean them up by calling tb_tunnel_deactivate() below in that
+	 * case.
+	 */
+	path = tb_path_discover(down, TB_USB3_HOPID, NULL, -1,
+				&tunnel->dst_port, "USB3 Up");
+	if (!path) {
+		/* Just disable the downstream port */
+		tb_usb3_port_enable(down, false);
+		goto err_free;
+	}
+	tunnel->paths[TB_USB3_PATH_UP] = path;
+	tb_usb3_init_path(tunnel->paths[TB_USB3_PATH_UP]);
+
+	path = tb_path_discover(tunnel->dst_port, -1, down, TB_USB3_HOPID, NULL,
+				"USB3 Down");
+	if (!path)
+		goto err_deactivate;
+	tunnel->paths[TB_USB3_PATH_DOWN] = path;
+	tb_usb3_init_path(tunnel->paths[TB_USB3_PATH_DOWN]);
+
+	/* Validate that the tunnel is complete */
+	if (!tb_port_is_usb3_up(tunnel->dst_port)) {
+		tb_port_warn(tunnel->dst_port,
+			     "path does not end on an USB3 adapter, cleaning up\n");
+		goto err_deactivate;
+	}
+
+	if (down != tunnel->src_port) {
+		tb_tunnel_warn(tunnel, "path is not complete, cleaning up\n");
+		goto err_deactivate;
+	}
+
+	if (!tb_usb3_port_is_enabled(tunnel->dst_port)) {
+		tb_tunnel_warn(tunnel,
+			       "tunnel is not fully activated, 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_usb3() - allocate a USB3 tunnel
+ * @tb: Pointer to the domain structure
+ * @up: USB3 upstream adapter port
+ * @down: USB3 downstream adapter port
+ *
+ * Allocate an USB3 tunnel. The ports must be of type @TB_TYPE_USB3_UP and
+ * @TB_TYPE_USB3_DOWN.
+ *
+ * Return: Returns a tb_tunnel on success or %NULL on failure.
+ */
+struct tb_tunnel *tb_tunnel_alloc_usb3(struct tb *tb, struct tb_port *up,
+				       struct tb_port *down)
+{
+	struct tb_tunnel *tunnel;
+	struct tb_path *path;
+
+	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_USB3);
+	if (!tunnel)
+		return NULL;
+
+	tunnel->activate = tb_usb3_activate;
+	tunnel->src_port = down;
+	tunnel->dst_port = up;
+
+	path = tb_path_alloc(tb, down, TB_USB3_HOPID, up, TB_USB3_HOPID, 0,
+			     "USB3 Down");
+	if (!path) {
+		tb_tunnel_free(tunnel);
+		return NULL;
+	}
+	tb_usb3_init_path(path);
+	tunnel->paths[TB_USB3_PATH_DOWN] = path;
+
+	path = tb_path_alloc(tb, up, TB_USB3_HOPID, down, TB_USB3_HOPID, 0,
+			     "USB3 Up");
+	if (!path) {
+		tb_tunnel_free(tunnel);
+		return NULL;
+	}
+	tb_usb3_init_path(path);
+	tunnel->paths[TB_USB3_PATH_UP] = path;
+
+	return tunnel;
+}
+
 /**
  * tb_tunnel_free() - free a tunnel
  * @tunnel: Tunnel to be freed