thunderbolt: Add initial support for USB4

USB4 is the public specification based on Thunderbolt 3 protocol. There
are some differences in register layouts and flows. In addition to PCIe
and DP tunneling, USB4 supports tunneling of USB 3.x. USB4 is also
backward compatible with Thunderbolt 3 (and older generations but the
spec only talks about 3rd generation). USB4 compliant devices can be
identified by checking USB4 version field in router configuration space.

This patch adds initial support for USB4 compliant hosts and devices
which enables following features provided by the existing functionality
in the driver:

  - PCIe tunneling
  - Display Port tunneling
  - Host and device NVM firmware upgrade
  - P2P networking

This brings the USB4 support to the same level that we already have for
Thunderbolt 1, 2 and 3 devices.

Note the spec talks about host and device "routers" but in the driver we
still use term "switch" in most places. Both can be used interchangeably.

Co-developed-by: Rajmohan Mani <rajmohan.mani@intel.com>
Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20191217123345.31850-5-mika.westerberg@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 14 insertions, 6 deletions

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index e54d0d89a32d..6b99dcd1790c 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -365,12 +365,15 @@ static struct tb_port *tb_find_unused_port(struct tb_switch *sw,
 static struct tb_port *tb_find_pcie_down(struct tb_switch *sw,
 					 const struct tb_port *port)
 {
+	struct tb_port *down = NULL;
+
 	/*
 	 * To keep plugging devices consistently in the same PCIe
-	 * hierarchy, do mapping here for root switch downstream PCIe
-	 * ports.
+	 * hierarchy, do mapping here for switch downstream PCIe ports.
 	 */
-	if (!tb_route(sw)) {
+	if (tb_switch_is_usb4(sw)) {
+		down = usb4_switch_map_pcie_down(sw, port);
+	} else if (!tb_route(sw)) {
 		int phy_port = tb_phy_port_from_link(port->port);
 		int index;
 
@@ -391,12 +394,17 @@ static struct tb_port *tb_find_pcie_down(struct tb_switch *sw,
 		/* Validate the hard-coding */
 		if (WARN_ON(index > sw->config.max_port_number))
 			goto out;
-		if (WARN_ON(!tb_port_is_pcie_down(&sw->ports[index])))
+
+		down = &sw->ports[index];
+	}
+
+	if (down) {
+		if (WARN_ON(!tb_port_is_pcie_down(down)))
 			goto out;
-		if (WARN_ON(tb_pci_port_is_enabled(&sw->ports[index])))
+		if (WARN_ON(tb_pci_port_is_enabled(down)))
 			goto out;
 
-		return &sw->ports[index];
+		return down;
 	}
 
 out: