thunderbolt: Add support for simple pci tunnels

A pci downstream and pci upstream port can be connected through a
tunnel. To establish the tunnel we have to setup two unidirectional
paths between the two ports.

Right now we only support paths with two hops (i.e. no chaining) and at
most one pci device per thunderbolt device.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 232 insertions, 0 deletions

diff --git a/drivers/thunderbolt/tunnel_pci.c b/drivers/thunderbolt/tunnel_pci.c
new file mode 100644
index 000000000000..baf1cd370446
--- /dev/null
+++ b/drivers/thunderbolt/tunnel_pci.c
@@ -0,0 +1,232 @@
+/*
+ * Thunderbolt Cactus Ridge driver - PCIe tunnel
+ *
+ * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/list.h>
+
+#include "tunnel_pci.h"
+#include "tb.h"
+
+#define __TB_TUNNEL_PRINT(level, tunnel, fmt, arg...)                   \
+	do {                                                            \
+		struct tb_pci_tunnel *__tunnel = (tunnel);              \
+		level(__tunnel->tb, "%llx:%x <-> %llx:%x (PCI): " fmt,  \
+		      tb_route(__tunnel->down_port->sw),                \
+		      __tunnel->down_port->port,                        \
+		      tb_route(__tunnel->up_port->sw),                  \
+		      __tunnel->up_port->port,                          \
+		      ## arg);                                          \
+	} while (0)
+
+#define tb_tunnel_WARN(tunnel, fmt, arg...) \
+	__TB_TUNNEL_PRINT(tb_WARN, tunnel, fmt, ##arg)
+#define tb_tunnel_warn(tunnel, fmt, arg...) \
+	__TB_TUNNEL_PRINT(tb_warn, tunnel, fmt, ##arg)
+#define tb_tunnel_info(tunnel, fmt, arg...) \
+	__TB_TUNNEL_PRINT(tb_info, tunnel, fmt, ##arg)
+
+static void tb_pci_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 = 1;
+	path->drop_packages = 0;
+	path->nfc_credits = 0;
+}
+
+/**
+ * tb_pci_alloc() - allocate a pci tunnel
+ *
+ * Allocate a PCI tunnel. The ports must be of type TB_TYPE_PCIE_UP and
+ * TB_TYPE_PCIE_DOWN.
+ *
+ * Currently only paths consisting of two hops are supported (that is the
+ * ports must be on "adjacent" switches).
+ *
+ * The paths are hard-coded to use hop 8 (the only working hop id available on
+ * my thunderbolt devices). Therefore at most ONE path per device may be
+ * activated.
+ *
+ * Return: Returns a tb_pci_tunnel on success or NULL on failure.
+ */
+struct tb_pci_tunnel *tb_pci_alloc(struct tb *tb, struct tb_port *up,
+				   struct tb_port *down)
+{
+	struct tb_pci_tunnel *tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL);
+	if (!tunnel)
+		goto err;
+	tunnel->tb = tb;
+	tunnel->down_port = down;
+	tunnel->up_port = up;
+	INIT_LIST_HEAD(&tunnel->list);
+	tunnel->path_to_up = tb_path_alloc(up->sw->tb, 2);
+	if (!tunnel->path_to_up)
+		goto err;
+	tunnel->path_to_down = tb_path_alloc(up->sw->tb, 2);
+	if (!tunnel->path_to_down)
+		goto err;
+	tb_pci_init_path(tunnel->path_to_up);
+	tb_pci_init_path(tunnel->path_to_down);
+
+	tunnel->path_to_up->hops[0].in_port = down;
+	tunnel->path_to_up->hops[0].in_hop_index = 8;
+	tunnel->path_to_up->hops[0].in_counter_index = -1;
+	tunnel->path_to_up->hops[0].out_port = tb_upstream_port(up->sw)->remote;
+	tunnel->path_to_up->hops[0].next_hop_index = 8;
+
+	tunnel->path_to_up->hops[1].in_port = tb_upstream_port(up->sw);
+	tunnel->path_to_up->hops[1].in_hop_index = 8;
+	tunnel->path_to_up->hops[1].in_counter_index = -1;
+	tunnel->path_to_up->hops[1].out_port = up;
+	tunnel->path_to_up->hops[1].next_hop_index = 8;
+
+	tunnel->path_to_down->hops[0].in_port = up;
+	tunnel->path_to_down->hops[0].in_hop_index = 8;
+	tunnel->path_to_down->hops[0].in_counter_index = -1;
+	tunnel->path_to_down->hops[0].out_port = tb_upstream_port(up->sw);
+	tunnel->path_to_down->hops[0].next_hop_index = 8;
+
+	tunnel->path_to_down->hops[1].in_port =
+		tb_upstream_port(up->sw)->remote;
+	tunnel->path_to_down->hops[1].in_hop_index = 8;
+	tunnel->path_to_down->hops[1].in_counter_index = -1;
+	tunnel->path_to_down->hops[1].out_port = down;
+	tunnel->path_to_down->hops[1].next_hop_index = 8;
+	return tunnel;
+
+err:
+	if (tunnel) {
+		if (tunnel->path_to_down)
+			tb_path_free(tunnel->path_to_down);
+		if (tunnel->path_to_up)
+			tb_path_free(tunnel->path_to_up);
+		kfree(tunnel);
+	}
+	return NULL;
+}
+
+/**
+ * tb_pci_free() - free a tunnel
+ *
+ * The tunnel must have been deactivated.
+ */
+void tb_pci_free(struct tb_pci_tunnel *tunnel)
+{
+	if (tunnel->path_to_up->activated || tunnel->path_to_down->activated) {
+		tb_tunnel_WARN(tunnel, "trying to free an activated tunnel\n");
+		return;
+	}
+	tb_path_free(tunnel->path_to_up);
+	tb_path_free(tunnel->path_to_down);
+	kfree(tunnel);
+}
+
+/**
+ * tb_pci_is_invalid - check whether an activated path is still valid
+ */
+bool tb_pci_is_invalid(struct tb_pci_tunnel *tunnel)
+{
+	WARN_ON(!tunnel->path_to_up->activated);
+	WARN_ON(!tunnel->path_to_down->activated);
+
+	return tb_path_is_invalid(tunnel->path_to_up)
+	       || tb_path_is_invalid(tunnel->path_to_down);
+}
+
+/**
+ * tb_pci_port_active() - activate/deactivate PCI capability
+ *
+ * Return: Returns 0 on success or an error code on failure.
+ */
+static int tb_pci_port_active(struct tb_port *port, bool active)
+{
+	u32 word = active ? 0x80000000 : 0x0;
+	int cap = tb_find_cap(port, TB_CFG_PORT, TB_CAP_PCIE);
+	if (cap <= 0) {
+		tb_port_warn(port, "TB_CAP_PCIE not found: %d\n", cap);
+		return cap ? cap : -ENXIO;
+	}
+	return tb_port_write(port, &word, TB_CFG_PORT, cap, 1);
+}
+
+/**
+ * tb_pci_restart() - activate a tunnel after a hardware reset
+ */
+int tb_pci_restart(struct tb_pci_tunnel *tunnel)
+{
+	int res;
+	tunnel->path_to_up->activated = false;
+	tunnel->path_to_down->activated = false;
+
+	tb_tunnel_info(tunnel, "activating\n");
+
+	res = tb_path_activate(tunnel->path_to_up);
+	if (res)
+		goto err;
+	res = tb_path_activate(tunnel->path_to_down);
+	if (res)
+		goto err;
+
+	res = tb_pci_port_active(tunnel->down_port, true);
+	if (res)
+		goto err;
+
+	res = tb_pci_port_active(tunnel->up_port, true);
+	if (res)
+		goto err;
+	return 0;
+err:
+	tb_tunnel_warn(tunnel, "activation failed\n");
+	tb_pci_deactivate(tunnel);
+	return res;
+}
+
+/**
+ * tb_pci_activate() - activate a tunnel
+ *
+ * Return: Returns 0 on success or an error code on failure.
+ */
+int tb_pci_activate(struct tb_pci_tunnel *tunnel)
+{
+	int res;
+	if (tunnel->path_to_up->activated || tunnel->path_to_down->activated) {
+		tb_tunnel_WARN(tunnel,
+			       "trying to activate an already activated tunnel\n");
+		return -EINVAL;
+	}
+
+	res = tb_pci_restart(tunnel);
+	if (res)
+		return res;
+
+	list_add(&tunnel->list, &tunnel->tb->tunnel_list);
+	return 0;
+}
+
+
+
+/**
+ * tb_pci_deactivate() - deactivate a tunnel
+ */
+void tb_pci_deactivate(struct tb_pci_tunnel *tunnel)
+{
+	tb_tunnel_info(tunnel, "deactivating\n");
+	/*
+	 * TODO: enable reset by writing 0x04000000 to TB_CAP_PCIE + 1 on up
+	 * port. Seems to have no effect?
+	 */
+	tb_pci_port_active(tunnel->up_port, false);
+	tb_pci_port_active(tunnel->down_port, false);
+	if (tunnel->path_to_down->activated)
+		tb_path_deactivate(tunnel->path_to_down);
+	if (tunnel->path_to_up->activated)
+		tb_path_deactivate(tunnel->path_to_up);
+	list_del_init(&tunnel->list);
+}
+