thunderbolt: Discover preboot PCIe paths the boot firmware established

In Apple Macs the boot firmware (EFI) connects all devices automatically
when the system is started, before it hands over to the OS. Instead of
ignoring we discover all those PCIe tunnels and record them using our
internal structures, just like we do when a device is connected after
the OS is already up.

By doing this we can properly tear down tunnels when devices are
disconnected. Also this allows us to resume the existing tunnels after
system suspend/resume cycle.

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

1 files changed, 84 insertions, 2 deletions

diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index e109578da175..71c712300326 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -35,6 +35,8 @@
 	__TB_TUNNEL_PRINT(tb_warn, tunnel, fmt, ##arg)
 #define tb_tunnel_info(tunnel, fmt, arg...) \
 	__TB_TUNNEL_PRINT(tb_info, tunnel, fmt, ##arg)
+#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)
 {
@@ -65,7 +67,10 @@ static int tb_pci_activate(struct tb_tunnel *tunnel, bool activate)
 	if (res)
 		return res;
 
-	return tb_pci_port_enable(tunnel->dst_port, activate);
+	if (tb_port_is_pcie_up(tunnel->dst_port))
+		return tb_pci_port_enable(tunnel->dst_port, activate);
+
+	return 0;
 }
 
 static void tb_pci_init_path(struct tb_path *path)
@@ -78,6 +83,83 @@ static void tb_pci_init_path(struct tb_path *path)
 	path->weight = 1;
 	path->drop_packages = 0;
 	path->nfc_credits = 0;
+	path->hops[0].initial_credits = 7;
+	path->hops[1].initial_credits = 16;
+}
+
+/**
+ * tb_tunnel_discover_pci() - Discover existing PCIe tunnels
+ * @tb: Pointer to the domain structure
+ * @down: PCIe downstream adapter
+ *
+ * If @down adapter is active, follows the tunnel to the PCIe upstream
+ * adapter and back. Returns the discovered tunnel or %NULL if there was
+ * no tunnel.
+ */
+struct tb_tunnel *tb_tunnel_discover_pci(struct tb *tb, struct tb_port *down)
+{
+	struct tb_tunnel *tunnel;
+	struct tb_path *path;
+
+	if (!tb_pci_port_is_enabled(down))
+		return NULL;
+
+	tunnel = tb_tunnel_alloc(tb, 2);
+	if (!tunnel)
+		return NULL;
+
+	tunnel->activate = tb_pci_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_PCI_HOPID, NULL, -1,
+				&tunnel->dst_port, "PCIe Up");
+	if (!path) {
+		/* Just disable the downstream port */
+		tb_pci_port_enable(down, false);
+		goto err_free;
+	}
+	tunnel->paths[TB_PCI_PATH_UP] = path;
+	tb_pci_init_path(tunnel->paths[TB_PCI_PATH_UP]);
+
+	path = tb_path_discover(tunnel->dst_port, -1, down, TB_PCI_HOPID, NULL,
+				"PCIe Down");
+	if (!path)
+		goto err_deactivate;
+	tunnel->paths[TB_PCI_PATH_DOWN] = path;
+	tb_pci_init_path(tunnel->paths[TB_PCI_PATH_DOWN]);
+
+	/* Validate that the tunnel is complete */
+	if (!tb_port_is_pcie_up(tunnel->dst_port)) {
+		tb_port_warn(tunnel->dst_port,
+			     "path does not end on a PCIe 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_pci_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;
 }
 
 /**
@@ -253,7 +335,7 @@ void tb_tunnel_deactivate(struct tb_tunnel *tunnel)
 		tunnel->activate(tunnel, false);
 
 	for (i = 0; i < tunnel->npaths; i++) {
-		if (tunnel->paths[i]->activated)
+		if (tunnel->paths[i] && tunnel->paths[i]->activated)
 			tb_path_deactivate(tunnel->paths[i]);
 	}
 }