// SPDX-License-Identifier: GPL-2.0
/*
 * Thunderbolt driver - bus logic (NHI independent)
 *
 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
 * Copyright (C) 2019, Intel Corporation
 */

#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/pm_runtime.h>
#include <linux/platform_data/x86/apple.h>

#include "tb.h"
#include "tb_regs.h"
#include "tunnel.h"

#define TB_TIMEOUT      100 /* ms */

/**
 * struct tb_cm - Simple Thunderbolt connection manager
 * @tunnel_list: List of active tunnels
 * @dp_resources: List of available DP resources for DP tunneling
 * @hotplug_active: tb_handle_hotplug will stop progressing plug
 *                  events and exit if this is not set (it needs to
 *                  acquire the lock one more time). Used to drain wq
 *                  after cfg has been paused.
 * @remove_work: Work used to remove any unplugged routers after
 *               runtime resume
 */
struct tb_cm {
        struct list_head tunnel_list;
        struct list_head dp_resources;
        bool hotplug_active;
        struct delayed_work remove_work;
};

static inline struct tb *tcm_to_tb(struct tb_cm *tcm)
{
        return ((void *)tcm - sizeof(struct tb));
}

struct tb_hotplug_event {
        struct work_struct work;
        struct tb *tb;
        u64 route;
        u8 port;
        bool unplug;
};

static void tb_handle_hotplug(struct work_struct *work);

static void tb_queue_hotplug(struct tb *tb, u64 route, u8 port, bool unplug)
{
        struct tb_hotplug_event *ev;

        ev = kmalloc(sizeof(*ev), GFP_KERNEL);
        if (!ev)
                return;

        ev->tb = tb;
        ev->route = route;
        ev->port = port;
        ev->unplug = unplug;
        INIT_WORK(&ev->work, tb_handle_hotplug);
        queue_work(tb->wq, &ev->work);
}

/* enumeration & hot plug handling */

static void tb_add_dp_resources(struct tb_switch *sw)
{
        struct tb_cm *tcm = tb_priv(sw->tb);
        struct tb_port *port;

        tb_switch_for_each_port(sw, port) {
                if (!tb_port_is_dpin(port))
                        continue;

                if (!tb_switch_query_dp_resource(sw, port))
                        continue;

                list_add_tail(&port->list, &tcm->dp_resources);
                tb_port_dbg(port, "DP IN resource available\n");
        }
}

static void tb_remove_dp_resources(struct tb_switch *sw)
{
        struct tb_cm *tcm = tb_priv(sw->tb);
        struct tb_port *port, *tmp;

        /* Clear children resources first */
        tb_switch_for_each_port(sw, port) {
                if (tb_port_has_remote(port))
                        tb_remove_dp_resources(port->remote->sw);
        }

        list_for_each_entry_safe(port, tmp, &tcm->dp_resources, list) {
                if (port->sw == sw) {
                        tb_port_dbg(port, "DP OUT resource unavailable\n");
                        list_del_init(&port->list);
                }
        }
}

static void tb_discover_tunnels(struct tb_switch *sw)
{
        struct tb *tb = sw->tb;
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_port *port;

        tb_switch_for_each_port(sw, port) {
                struct tb_tunnel *tunnel = NULL;

                switch (port->config.type) {
                case TB_TYPE_DP_HDMI_IN:
                        tunnel = tb_tunnel_discover_dp(tb, port);
                        break;

                case TB_TYPE_PCIE_DOWN:
                        tunnel = tb_tunnel_discover_pci(tb, port);
                        break;

                case TB_TYPE_USB3_DOWN:
                        tunnel = tb_tunnel_discover_usb3(tb, port);
                        break;

                default:
                        break;
                }

                if (!tunnel)
                        continue;

                if (tb_tunnel_is_pci(tunnel)) {
                        struct tb_switch *parent = tunnel->dst_port->sw;

                        while (parent != tunnel->src_port->sw) {
                                parent->boot = true;
                                parent = tb_switch_parent(parent);
                        }
                } else if (tb_tunnel_is_dp(tunnel)) {
                        /* Keep the domain from powering down */
                        pm_runtime_get_sync(&tunnel->src_port->sw->dev);
                        pm_runtime_get_sync(&tunnel->dst_port->sw->dev);
                }

                list_add_tail(&tunnel->list, &tcm->tunnel_list);
        }

        tb_switch_for_each_port(sw, port) {
                if (tb_port_has_remote(port))
                        tb_discover_tunnels(port->remote->sw);
        }
}

static int tb_port_configure_xdomain(struct tb_port *port)
{
        /*
         * XDomain paths currently only support single lane so we must
         * disable the other lane according to USB4 spec.
         */
        tb_port_disable(port->dual_link_port);

        if (tb_switch_is_usb4(port->sw))
                return usb4_port_configure_xdomain(port);
        return tb_lc_configure_xdomain(port);
}

static void tb_port_unconfigure_xdomain(struct tb_port *port)
{
        if (tb_switch_is_usb4(port->sw))
                usb4_port_unconfigure_xdomain(port);
        else
                tb_lc_unconfigure_xdomain(port);

        tb_port_enable(port->dual_link_port);
}

static void tb_scan_xdomain(struct tb_port *port)
{
        struct tb_switch *sw = port->sw;
        struct tb *tb = sw->tb;
        struct tb_xdomain *xd;
        u64 route;

        if (!tb_is_xdomain_enabled())
                return;

        route = tb_downstream_route(port);
        xd = tb_xdomain_find_by_route(tb, route);
        if (xd) {
                tb_xdomain_put(xd);
                return;
        }

        xd = tb_xdomain_alloc(tb, &sw->dev, route, tb->root_switch->uuid,
                              NULL);
        if (xd) {
                tb_port_at(route, sw)->xdomain = xd;
                tb_port_configure_xdomain(port);
                tb_xdomain_add(xd);
        }
}

static int tb_enable_tmu(struct tb_switch *sw)
{
        int ret;

        /* If it is already enabled in correct mode, don't touch it */
        if (tb_switch_tmu_is_enabled(sw))
                return 0;

        ret = tb_switch_tmu_disable(sw);
        if (ret)
                return ret;

        ret = tb_switch_tmu_post_time(sw);
        if (ret)
                return ret;

        return tb_switch_tmu_enable(sw);
}

/**
 * tb_find_unused_port() - return the first inactive port on @sw
 * @sw: Switch to find the port on
 * @type: Port type to look for
 */
static struct tb_port *tb_find_unused_port(struct tb_switch *sw,
                                           enum tb_port_type type)
{
        struct tb_port *port;

        tb_switch_for_each_port(sw, port) {
                if (tb_is_upstream_port(port))
                        continue;
                if (port->config.type != type)
                        continue;
                if (!port->cap_adap)
                        continue;
                if (tb_port_is_enabled(port))
                        continue;
                return port;
        }
        return NULL;
}

static struct tb_port *tb_find_usb3_down(struct tb_switch *sw,
                                         const struct tb_port *port)
{
        struct tb_port *down;

        down = usb4_switch_map_usb3_down(sw, port);
        if (down && !tb_usb3_port_is_enabled(down))
                return down;
        return NULL;
}

static struct tb_tunnel *tb_find_tunnel(struct tb *tb, enum tb_tunnel_type type,
                                        struct tb_port *src_port,
                                        struct tb_port *dst_port)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel;

        list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
                if (tunnel->type == type &&
                    ((src_port && src_port == tunnel->src_port) ||
                     (dst_port && dst_port == tunnel->dst_port))) {
                        return tunnel;
                }
        }

        return NULL;
}

static struct tb_tunnel *tb_find_first_usb3_tunnel(struct tb *tb,
                                                   struct tb_port *src_port,
                                                   struct tb_port *dst_port)
{
        struct tb_port *port, *usb3_down;
        struct tb_switch *sw;

        /* Pick the router that is deepest in the topology */
        if (dst_port->sw->config.depth > src_port->sw->config.depth)
                sw = dst_port->sw;
        else
                sw = src_port->sw;

        /* Can't be the host router */
        if (sw == tb->root_switch)
                return NULL;

        /* Find the downstream USB4 port that leads to this router */
        port = tb_port_at(tb_route(sw), tb->root_switch);
        /* Find the corresponding host router USB3 downstream port */
        usb3_down = usb4_switch_map_usb3_down(tb->root_switch, port);
        if (!usb3_down)
                return NULL;

        return tb_find_tunnel(tb, TB_TUNNEL_USB3, usb3_down, NULL);
}

static int tb_available_bandwidth(struct tb *tb, struct tb_port *src_port,
        struct tb_port *dst_port, int *available_up, int *available_down)
{
        int usb3_consumed_up, usb3_consumed_down, ret;
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel;
        struct tb_port *port;

        tb_port_dbg(dst_port, "calculating available bandwidth\n");

        tunnel = tb_find_first_usb3_tunnel(tb, src_port, dst_port);
        if (tunnel) {
                ret = tb_tunnel_consumed_bandwidth(tunnel, &usb3_consumed_up,
                                                   &usb3_consumed_down);
                if (ret)
                        return ret;
        } else {
                usb3_consumed_up = 0;
                usb3_consumed_down = 0;
        }

        *available_up = *available_down = 40000;

        /* Find the minimum available bandwidth over all links */
        tb_for_each_port_on_path(src_port, dst_port, port) {
                int link_speed, link_width, up_bw, down_bw;

                if (!tb_port_is_null(port))
                        continue;

                if (tb_is_upstream_port(port)) {
                        link_speed = port->sw->link_speed;
                } else {
                        link_speed = tb_port_get_link_speed(port);
                        if (link_speed < 0)
                                return link_speed;
                }

                link_width = port->bonded ? 2 : 1;

                up_bw = link_speed * link_width * 1000; /* Mb/s */
                /* Leave 10% guard band */
                up_bw -= up_bw / 10;
                down_bw = up_bw;

                tb_port_dbg(port, "link total bandwidth %d Mb/s\n", up_bw);

                /*
                 * Find all DP tunnels that cross the port and reduce
                 * their consumed bandwidth from the available.
                 */
                list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
                        int dp_consumed_up, dp_consumed_down;

                        if (!tb_tunnel_is_dp(tunnel))
                                continue;

                        if (!tb_tunnel_port_on_path(tunnel, port))
                                continue;

                        ret = tb_tunnel_consumed_bandwidth(tunnel,
                                                           &dp_consumed_up,
                                                           &dp_consumed_down);
                        if (ret)
                                return ret;

                        up_bw -= dp_consumed_up;
                        down_bw -= dp_consumed_down;
                }

                /*
                 * If USB3 is tunneled from the host router down to the
                 * branch leading to port we need to take USB3 consumed
                 * bandwidth into account regardless whether it actually
                 * crosses the port.
                 */
                up_bw -= usb3_consumed_up;
                down_bw -= usb3_consumed_down;

                if (up_bw < *available_up)
                        *available_up = up_bw;
                if (down_bw < *available_down)
                        *available_down = down_bw;
        }

        if (*available_up < 0)
                *available_up = 0;
        if (*available_down < 0)
                *available_down = 0;

        return 0;
}

static int tb_release_unused_usb3_bandwidth(struct tb *tb,
                                            struct tb_port *src_port,
                                            struct tb_port *dst_port)
{
        struct tb_tunnel *tunnel;

        tunnel = tb_find_first_usb3_tunnel(tb, src_port, dst_port);
        return tunnel ? tb_tunnel_release_unused_bandwidth(tunnel) : 0;
}

static void tb_reclaim_usb3_bandwidth(struct tb *tb, struct tb_port *src_port,
                                      struct tb_port *dst_port)
{
        int ret, available_up, available_down;
        struct tb_tunnel *tunnel;

        tunnel = tb_find_first_usb3_tunnel(tb, src_port, dst_port);
        if (!tunnel)
                return;

        tb_dbg(tb, "reclaiming unused bandwidth for USB3\n");

        /*
         * Calculate available bandwidth for the first hop USB3 tunnel.
         * That determines the whole USB3 bandwidth for this branch.
         */
        ret = tb_available_bandwidth(tb, tunnel->src_port, tunnel->dst_port,
                                     &available_up, &available_down);
        if (ret) {
                tb_warn(tb, "failed to calculate available bandwidth\n");
                return;
        }

        tb_dbg(tb, "available bandwidth for USB3 %d/%d Mb/s\n",
               available_up, available_down);

        tb_tunnel_reclaim_available_bandwidth(tunnel, &available_up, &available_down);
}

static int tb_tunnel_usb3(struct tb *tb, struct tb_switch *sw)
{
        struct tb_switch *parent = tb_switch_parent(sw);
        int ret, available_up, available_down;
        struct tb_port *up, *down, *port;
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel;

        if (!tb_acpi_may_tunnel_usb3()) {
                tb_dbg(tb, "USB3 tunneling disabled, not creating tunnel\n");
                return 0;
        }

        up = tb_switch_find_port(sw, TB_TYPE_USB3_UP);
        if (!up)
                return 0;

        if (!sw->link_usb4)
                return 0;

        /*
         * Look up available down port. Since we are chaining it should
         * be found right above this switch.
         */
        port = tb_port_at(tb_route(sw), parent);
        down = tb_find_usb3_down(parent, port);
        if (!down)
                return 0;

        if (tb_route(parent)) {
                struct tb_port *parent_up;
                /*
                 * Check first that the parent switch has its upstream USB3
                 * port enabled. Otherwise the chain is not complete and
                 * there is no point setting up a new tunnel.
                 */
                parent_up = tb_switch_find_port(parent, TB_TYPE_USB3_UP);
                if (!parent_up || !tb_port_is_enabled(parent_up))
                        return 0;

                /* Make all unused bandwidth available for the new tunnel */
                ret = tb_release_unused_usb3_bandwidth(tb, down, up);
                if (ret)
                        return ret;
        }

        ret = tb_available_bandwidth(tb, down, up, &available_up,
                                     &available_down);
        if (ret)
                goto err_reclaim;

        tb_port_dbg(up, "available bandwidth for new USB3 tunnel %d/%d Mb/s\n",
                    available_up, available_down);

        tunnel = tb_tunnel_alloc_usb3(tb, up, down, available_up,
                                      available_down);
        if (!tunnel) {
                ret = -ENOMEM;
                goto err_reclaim;
        }

        if (tb_tunnel_activate(tunnel)) {
                tb_port_info(up,
                             "USB3 tunnel activation failed, aborting\n");
                ret = -EIO;
                goto err_free;
        }

        list_add_tail(&tunnel->list, &tcm->tunnel_list);
        if (tb_route(parent))
                tb_reclaim_usb3_bandwidth(tb, down, up);

        return 0;

err_free:
        tb_tunnel_free(tunnel);
err_reclaim:
        if (tb_route(parent))
                tb_reclaim_usb3_bandwidth(tb, down, up);

        return ret;
}

static int tb_create_usb3_tunnels(struct tb_switch *sw)
{
        struct tb_port *port;
        int ret;

        if (!tb_acpi_may_tunnel_usb3())
                return 0;

        if (tb_route(sw)) {
                ret = tb_tunnel_usb3(sw->tb, sw);
                if (ret)
                        return ret;
        }

        tb_switch_for_each_port(sw, port) {
                if (!tb_port_has_remote(port))
                        continue;
                ret = tb_create_usb3_tunnels(port->remote->sw);
                if (ret)
                        return ret;
        }

        return 0;
}

static void tb_scan_port(struct tb_port *port);

/*
 * tb_scan_switch() - scan for and initialize downstream switches
 */
static void tb_scan_switch(struct tb_switch *sw)
{
        struct tb_port *port;

        pm_runtime_get_sync(&sw->dev);

        tb_switch_for_each_port(sw, port)
                tb_scan_port(port);

        pm_runtime_mark_last_busy(&sw->dev);
        pm_runtime_put_autosuspend(&sw->dev);
}

/*
 * tb_scan_port() - check for and initialize switches below port
 */
static void tb_scan_port(struct tb_port *port)
{
        struct tb_cm *tcm = tb_priv(port->sw->tb);
        struct tb_port *upstream_port;
        struct tb_switch *sw;

        if (tb_is_upstream_port(port))
                return;

        if (tb_port_is_dpout(port) && tb_dp_port_hpd_is_active(port) == 1 &&
            !tb_dp_port_is_enabled(port)) {
                tb_port_dbg(port, "DP adapter HPD set, queuing hotplug\n");
                tb_queue_hotplug(port->sw->tb, tb_route(port->sw), port->port,
                                 false);
                return;
        }

        if (port->config.type != TB_TYPE_PORT)
                return;
        if (port->dual_link_port && port->link_nr)
                return; /*
                         * Downstream switch is reachable through two ports.
                         * Only scan on the primary port (link_nr == 0).
                         */
        if (tb_wait_for_port(port, false) <= 0)
                return;
        if (port->remote) {
                tb_port_dbg(port, "port already has a remote\n");
                return;
        }

        tb_retimer_scan(port, true);

        sw = tb_switch_alloc(port->sw->tb, &port->sw->dev,
                             tb_downstream_route(port));
        if (IS_ERR(sw)) {
                /*
                 * If there is an error accessing the connected switch
                 * it may be connected to another domain. Also we allow
                 * the other domain to be connected to a max depth switch.
                 */
                if (PTR_ERR(sw) == -EIO || PTR_ERR(sw) == -EADDRNOTAVAIL)
                        tb_scan_xdomain(port);
                return;
        }

        if (tb_switch_configure(sw)) {
                tb_switch_put(sw);
                return;
        }

        /*
         * If there was previously another domain connected remove it
         * first.
         */
        if (port->xdomain) {
                tb_xdomain_remove(port->xdomain);
                tb_port_unconfigure_xdomain(port);
                port->xdomain = NULL;
        }

        /*
         * Do not send uevents until we have discovered all existing
         * tunnels and know which switches were authorized already by
         * the boot firmware.
         */
        if (!tcm->hotplug_active)
                dev_set_uevent_suppress(&sw->dev, true);

        /*
         * At the moment Thunderbolt 2 and beyond (devices with LC) we
         * can support runtime PM.
         */
        sw->rpm = sw->generation > 1;

        if (tb_switch_add(sw)) {
                tb_switch_put(sw);
                return;
        }

        /* Link the switches using both links if available */
        upstream_port = tb_upstream_port(sw);
        port->remote = upstream_port;
        upstream_port->remote = port;
        if (port->dual_link_port && upstream_port->dual_link_port) {
                port->dual_link_port->remote = upstream_port->dual_link_port;
                upstream_port->dual_link_port->remote = port->dual_link_port;
        }

        /* Enable lane bonding if supported */
        tb_switch_lane_bonding_enable(sw);
        /* Set the link configured */
        tb_switch_configure_link(sw);

        if (tb_enable_tmu(sw))
                tb_sw_warn(sw, "failed to enable TMU\n");

        /* Scan upstream retimers */
        tb_retimer_scan(upstream_port, true);

        /*
         * Create USB 3.x tunnels only when the switch is plugged to the
         * domain. This is because we scan the domain also during discovery
         * and want to discover existing USB 3.x tunnels before we create
         * any new.
         */
        if (tcm->hotplug_active && tb_tunnel_usb3(sw->tb, sw))
                tb_sw_warn(sw, "USB3 tunnel creation failed\n");

        tb_add_dp_resources(sw);
        tb_scan_switch(sw);
}

static void tb_deactivate_and_free_tunnel(struct tb_tunnel *tunnel)
{
        struct tb_port *src_port, *dst_port;
        struct tb *tb;

        if (!tunnel)
                return;

        tb_tunnel_deactivate(tunnel);
        list_del(&tunnel->list);

        tb = tunnel->tb;
        src_port = tunnel->src_port;
        dst_port = tunnel->dst_port;

        switch (tunnel->type) {
        case TB_TUNNEL_DP:
                /*
                 * In case of DP tunnel make sure the DP IN resource is
                 * deallocated properly.
                 */
                tb_switch_dealloc_dp_resource(src_port->sw, src_port);
                /* Now we can allow the domain to runtime suspend again */
                pm_runtime_mark_last_busy(&dst_port->sw->dev);
                pm_runtime_put_autosuspend(&dst_port->sw->dev);
                pm_runtime_mark_last_busy(&src_port->sw->dev);
                pm_runtime_put_autosuspend(&src_port->sw->dev);
                fallthrough;

        case TB_TUNNEL_USB3:
                tb_reclaim_usb3_bandwidth(tb, src_port, dst_port);
                break;

        default:
                /*
                 * PCIe and DMA tunnels do not consume guaranteed
                 * bandwidth.
                 */
                break;
        }

        tb_tunnel_free(tunnel);
}

/*
 * tb_free_invalid_tunnels() - destroy tunnels of devices that have gone away
 */
static void tb_free_invalid_tunnels(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel;
        struct tb_tunnel *n;

        list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list) {
                if (tb_tunnel_is_invalid(tunnel))
                        tb_deactivate_and_free_tunnel(tunnel);
        }
}

/*
 * tb_free_unplugged_children() - traverse hierarchy and free unplugged switches
 */
static void tb_free_unplugged_children(struct tb_switch *sw)
{
        struct tb_port *port;

        tb_switch_for_each_port(sw, port) {
                if (!tb_port_has_remote(port))
                        continue;

                if (port->remote->sw->is_unplugged) {
                        tb_retimer_remove_all(port);
                        tb_remove_dp_resources(port->remote->sw);
                        tb_switch_unconfigure_link(port->remote->sw);
                        tb_switch_lane_bonding_disable(port->remote->sw);
                        tb_switch_remove(port->remote->sw);
                        port->remote = NULL;
                        if (port->dual_link_port)
                                port->dual_link_port->remote = NULL;
                } else {
                        tb_free_unplugged_children(port->remote->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 switch downstream PCIe ports.
         */
        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;

                /*
                 * Hard-coded Thunderbolt port to PCIe down port mapping
                 * per controller.
                 */
                if (tb_switch_is_cactus_ridge(sw) ||
                    tb_switch_is_alpine_ridge(sw))
                        index = !phy_port ? 6 : 7;
                else if (tb_switch_is_falcon_ridge(sw))
                        index = !phy_port ? 6 : 8;
                else if (tb_switch_is_titan_ridge(sw))
                        index = !phy_port ? 8 : 9;
                else
                        goto out;

                /* Validate the hard-coding */
                if (WARN_ON(index > sw->config.max_port_number))
                        goto out;

                down = &sw->ports[index];
        }

        if (down) {
                if (WARN_ON(!tb_port_is_pcie_down(down)))
                        goto out;
                if (tb_pci_port_is_enabled(down))
                        goto out;

                return down;
        }

out:
        return tb_find_unused_port(sw, TB_TYPE_PCIE_DOWN);
}

static struct tb_port *tb_find_dp_out(struct tb *tb, struct tb_port *in)
{
        struct tb_port *host_port, *port;
        struct tb_cm *tcm = tb_priv(tb);

        host_port = tb_route(in->sw) ?
                tb_port_at(tb_route(in->sw), tb->root_switch) : NULL;

        list_for_each_entry(port, &tcm->dp_resources, list) {
                if (!tb_port_is_dpout(port))
                        continue;

                if (tb_port_is_enabled(port)) {
                        tb_port_dbg(port, "in use\n");
                        continue;
                }

                tb_port_dbg(port, "DP OUT available\n");

                /*
                 * Keep the DP tunnel under the topology starting from
                 * the same host router downstream port.
                 */
                if (host_port && tb_route(port->sw)) {
                        struct tb_port *p;

                        p = tb_port_at(tb_route(port->sw), tb->root_switch);
                        if (p != host_port)
                                continue;
                }

                return port;
        }

        return NULL;
}

static void tb_tunnel_dp(struct tb *tb)
{
        int available_up, available_down, ret;
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_port *port, *in, *out;
        struct tb_tunnel *tunnel;

        if (!tb_acpi_may_tunnel_dp()) {
                tb_dbg(tb, "DP tunneling disabled, not creating tunnel\n");
                return;
        }

        /*
         * Find pair of inactive DP IN and DP OUT adapters and then
         * establish a DP tunnel between them.
         */
        tb_dbg(tb, "looking for DP IN <-> DP OUT pairs:\n");

        in = NULL;
        out = NULL;
        list_for_each_entry(port, &tcm->dp_resources, list) {
                if (!tb_port_is_dpin(port))
                        continue;

                if (tb_port_is_enabled(port)) {
                        tb_port_dbg(port, "in use\n");
                        continue;
                }

                tb_port_dbg(port, "DP IN available\n");

                out = tb_find_dp_out(tb, port);
                if (out) {
                        in = port;
                        break;
                }
        }

        if (!in) {
                tb_dbg(tb, "no suitable DP IN adapter available, not tunneling\n");
                return;
        }
        if (!out) {
                tb_dbg(tb, "no suitable DP OUT adapter available, not tunneling\n");
                return;
        }

        /*
         * DP stream needs the domain to be active so runtime resume
         * both ends of the tunnel.
         *
         * This should bring the routers in the middle active as well
         * and keeps the domain from runtime suspending while the DP
         * tunnel is active.
         */
        pm_runtime_get_sync(&in->sw->dev);
        pm_runtime_get_sync(&out->sw->dev);

        if (tb_switch_alloc_dp_resource(in->sw, in)) {
                tb_port_dbg(in, "no resource available for DP IN, not tunneling\n");
                goto err_rpm_put;
        }

        /* Make all unused USB3 bandwidth available for the new DP tunnel */
        ret = tb_release_unused_usb3_bandwidth(tb, in, out);
        if (ret) {
                tb_warn(tb, "failed to release unused bandwidth\n");
                goto err_dealloc_dp;
        }

        ret = tb_available_bandwidth(tb, in, out, &available_up,
                                     &available_down);
        if (ret)
                goto err_reclaim;

        tb_dbg(tb, "available bandwidth for new DP tunnel %u/%u Mb/s\n",
               available_up, available_down);

        tunnel = tb_tunnel_alloc_dp(tb, in, out, available_up, available_down);
        if (!tunnel) {
                tb_port_dbg(out, "could not allocate DP tunnel\n");
                goto err_reclaim;
        }

        if (tb_tunnel_activate(tunnel)) {
                tb_port_info(out, "DP tunnel activation failed, aborting\n");
                goto err_free;
        }

        list_add_tail(&tunnel->list, &tcm->tunnel_list);
        tb_reclaim_usb3_bandwidth(tb, in, out);
        return;

err_free:
        tb_tunnel_free(tunnel);
err_reclaim:
        tb_reclaim_usb3_bandwidth(tb, in, out);
err_dealloc_dp:
        tb_switch_dealloc_dp_resource(in->sw, in);
err_rpm_put:
        pm_runtime_mark_last_busy(&out->sw->dev);
        pm_runtime_put_autosuspend(&out->sw->dev);
        pm_runtime_mark_last_busy(&in->sw->dev);
        pm_runtime_put_autosuspend(&in->sw->dev);
}

static void tb_dp_resource_unavailable(struct tb *tb, struct tb_port *port)
{
        struct tb_port *in, *out;
        struct tb_tunnel *tunnel;

        if (tb_port_is_dpin(port)) {
                tb_port_dbg(port, "DP IN resource unavailable\n");
                in = port;
                out = NULL;
        } else {
                tb_port_dbg(port, "DP OUT resource unavailable\n");
                in = NULL;
                out = port;
        }

        tunnel = tb_find_tunnel(tb, TB_TUNNEL_DP, in, out);
        tb_deactivate_and_free_tunnel(tunnel);
        list_del_init(&port->list);

        /*
         * See if there is another DP OUT port that can be used for
         * to create another tunnel.
         */
        tb_tunnel_dp(tb);
}

static void tb_dp_resource_available(struct tb *tb, struct tb_port *port)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_port *p;

        if (tb_port_is_enabled(port))
                return;

        list_for_each_entry(p, &tcm->dp_resources, list) {
                if (p == port)
                        return;
        }

        tb_port_dbg(port, "DP %s resource available\n",
                    tb_port_is_dpin(port) ? "IN" : "OUT");
        list_add_tail(&port->list, &tcm->dp_resources);

        /* Look for suitable DP IN <-> DP OUT pairs now */
        tb_tunnel_dp(tb);
}

static void tb_disconnect_and_release_dp(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel, *n;

        /*
         * Tear down all DP tunnels and release their resources. They
         * will be re-established after resume based on plug events.
         */
        list_for_each_entry_safe_reverse(tunnel, n, &tcm->tunnel_list, list) {
                if (tb_tunnel_is_dp(tunnel))
                        tb_deactivate_and_free_tunnel(tunnel);
        }

        while (!list_empty(&tcm->dp_resources)) {
                struct tb_port *port;

                port = list_first_entry(&tcm->dp_resources,
                                        struct tb_port, list);
                list_del_init(&port->list);
        }
}

static int tb_disconnect_pci(struct tb *tb, struct tb_switch *sw)
{
        struct tb_tunnel *tunnel;
        struct tb_port *up;

        up = tb_switch_find_port(sw, TB_TYPE_PCIE_UP);
        if (WARN_ON(!up))
                return -ENODEV;

        tunnel = tb_find_tunnel(tb, TB_TUNNEL_PCI, NULL, up);
        if (WARN_ON(!tunnel))
                return -ENODEV;

        tb_tunnel_deactivate(tunnel);
        list_del(&tunnel->list);
        tb_tunnel_free(tunnel);
        return 0;
}

static int tb_tunnel_pci(struct tb *tb, struct tb_switch *sw)
{
        struct tb_port *up, *down, *port;
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_switch *parent_sw;
        struct tb_tunnel *tunnel;

        up = tb_switch_find_port(sw, TB_TYPE_PCIE_UP);
        if (!up)
                return 0;

        /*
         * Look up available down port. Since we are chaining it should
         * be found right above this switch.
         */
        parent_sw = tb_to_switch(sw->dev.parent);
        port = tb_port_at(tb_route(sw), parent_sw);
        down = tb_find_pcie_down(parent_sw, port);
        if (!down)
                return 0;

        tunnel = tb_tunnel_alloc_pci(tb, up, down);
        if (!tunnel)
                return -ENOMEM;

        if (tb_tunnel_activate(tunnel)) {
                tb_port_info(up,
                             "PCIe tunnel activation failed, aborting\n");
                tb_tunnel_free(tunnel);
                return -EIO;
        }

        list_add_tail(&tunnel->list, &tcm->tunnel_list);
        return 0;
}

static int tb_approve_xdomain_paths(struct tb *tb, struct tb_xdomain *xd,
                                    int transmit_path, int transmit_ring,
                                    int receive_path, int receive_ring)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_port *nhi_port, *dst_port;
        struct tb_tunnel *tunnel;
        struct tb_switch *sw;

        sw = tb_to_switch(xd->dev.parent);
        dst_port = tb_port_at(xd->route, sw);
        nhi_port = tb_switch_find_port(tb->root_switch, TB_TYPE_NHI);

        mutex_lock(&tb->lock);
        tunnel = tb_tunnel_alloc_dma(tb, nhi_port, dst_port, transmit_path,
                                     transmit_ring, receive_path, receive_ring);
        if (!tunnel) {
                mutex_unlock(&tb->lock);
                return -ENOMEM;
        }

        if (tb_tunnel_activate(tunnel)) {
                tb_port_info(nhi_port,
                             "DMA tunnel activation failed, aborting\n");
                tb_tunnel_free(tunnel);
                mutex_unlock(&tb->lock);
                return -EIO;
        }

        list_add_tail(&tunnel->list, &tcm->tunnel_list);
        mutex_unlock(&tb->lock);
        return 0;
}

static void __tb_disconnect_xdomain_paths(struct tb *tb, struct tb_xdomain *xd,
                                          int transmit_path, int transmit_ring,
                                          int receive_path, int receive_ring)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_port *nhi_port, *dst_port;
        struct tb_tunnel *tunnel, *n;
        struct tb_switch *sw;

        sw = tb_to_switch(xd->dev.parent);
        dst_port = tb_port_at(xd->route, sw);
        nhi_port = tb_switch_find_port(tb->root_switch, TB_TYPE_NHI);

        list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list) {
                if (!tb_tunnel_is_dma(tunnel))
                        continue;
                if (tunnel->src_port != nhi_port || tunnel->dst_port != dst_port)
                        continue;

                if (tb_tunnel_match_dma(tunnel, transmit_path, transmit_ring,
                                        receive_path, receive_ring))
                        tb_deactivate_and_free_tunnel(tunnel);
        }
}

static int tb_disconnect_xdomain_paths(struct tb *tb, struct tb_xdomain *xd,
                                       int transmit_path, int transmit_ring,
                                       int receive_path, int receive_ring)
{
        if (!xd->is_unplugged) {
                mutex_lock(&tb->lock);
                __tb_disconnect_xdomain_paths(tb, xd, transmit_path,
                                              transmit_ring, receive_path,
                                              receive_ring);
                mutex_unlock(&tb->lock);
        }
        return 0;
}

/* hotplug handling */

/*
 * tb_handle_hotplug() - handle hotplug event
 *
 * Executes on tb->wq.
 */
static void tb_handle_hotplug(struct work_struct *work)
{
        struct tb_hotplug_event *ev = container_of(work, typeof(*ev), work);
        struct tb *tb = ev->tb;
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_switch *sw;
        struct tb_port *port;

        /* Bring the domain back from sleep if it was suspended */
        pm_runtime_get_sync(&tb->dev);

        mutex_lock(&tb->lock);
        if (!tcm->hotplug_active)
                goto out; /* during init, suspend or shutdown */

        sw = tb_switch_find_by_route(tb, ev->route);
        if (!sw) {
                tb_warn(tb,
                        "hotplug event from non existent switch %llx:%x (unplug: %d)\n",
                        ev->route, ev->port, ev->unplug);
                goto out;
        }
        if (ev->port > sw->config.max_port_number) {
                tb_warn(tb,
                        "hotplug event from non existent port %llx:%x (unplug: %d)\n",
                        ev->route, ev->port, ev->unplug);
                goto put_sw;
        }
        port = &sw->ports[ev->port];
        if (tb_is_upstream_port(port)) {
                tb_dbg(tb, "hotplug event for upstream port %llx:%x (unplug: %d)\n",
                       ev->route, ev->port, ev->unplug);
                goto put_sw;
        }

        pm_runtime_get_sync(&sw->dev);

        if (ev->unplug) {
                tb_retimer_remove_all(port);

                if (tb_port_has_remote(port)) {
                        tb_port_dbg(port, "switch unplugged\n");
                        tb_sw_set_unplugged(port->remote->sw);
                        tb_free_invalid_tunnels(tb);
                        tb_remove_dp_resources(port->remote->sw);
                        tb_switch_tmu_disable(port->remote->sw);
                        tb_switch_unconfigure_link(port->remote->sw);
                        tb_switch_lane_bonding_disable(port->remote->sw);
                        tb_switch_remove(port->remote->sw);
                        port->remote = NULL;
                        if (port->dual_link_port)
                                port->dual_link_port->remote = NULL;
                        /* Maybe we can create another DP tunnel */
                        tb_tunnel_dp(tb);
                } else if (port->xdomain) {
                        struct tb_xdomain *xd = tb_xdomain_get(port->xdomain);

                        tb_port_dbg(port, "xdomain unplugged\n");
                        /*
                         * Service drivers are unbound during
                         * tb_xdomain_remove() so setting XDomain as
                         * unplugged here prevents deadlock if they call
                         * tb_xdomain_disable_paths(). We will tear down
                         * all the tunnels below.
                         */
                        xd->is_unplugged = true;
                        tb_xdomain_remove(xd);
                        port->xdomain = NULL;
                        __tb_disconnect_xdomain_paths(tb, xd, -1, -1, -1, -1);
                        tb_xdomain_put(xd);
                        tb_port_unconfigure_xdomain(port);
                } else if (tb_port_is_dpout(port) || tb_port_is_dpin(port)) {
                        tb_dp_resource_unavailable(tb, port);
                } else {
                        tb_port_dbg(port,
                                   "got unplug event for disconnected port, ignoring\n");
                }
        } else if (port->remote) {
                tb_port_dbg(port, "got plug event for connected port, ignoring\n");
        } else {
                if (tb_port_is_null(port)) {
                        tb_port_dbg(port, "hotplug: scanning\n");
                        tb_scan_port(port);
                        if (!port->remote)
                                tb_port_dbg(port, "hotplug: no switch found\n");
                } else if (tb_port_is_dpout(port) || tb_port_is_dpin(port)) {
                        tb_dp_resource_available(tb, port);
                }
        }

        pm_runtime_mark_last_busy(&sw->dev);
        pm_runtime_put_autosuspend(&sw->dev);

put_sw:
        tb_switch_put(sw);
out:
        mutex_unlock(&tb->lock);

        pm_runtime_mark_last_busy(&tb->dev);
        pm_runtime_put_autosuspend(&tb->dev);

        kfree(ev);
}

/*
 * tb_schedule_hotplug_handler() - callback function for the control channel
 *
 * Delegates to tb_handle_hotplug.
 */
static void tb_handle_event(struct tb *tb, enum tb_cfg_pkg_type type,
                            const void *buf, size_t size)
{
        const struct cfg_event_pkg *pkg = buf;
        u64 route;

        if (type != TB_CFG_PKG_EVENT) {
                tb_warn(tb, "unexpected event %#x, ignoring\n", type);
                return;
        }

        route = tb_cfg_get_route(&pkg->header);

        if (tb_cfg_ack_plug(tb->ctl, route, pkg->port, pkg->unplug)) {
                tb_warn(tb, "could not ack plug event on %llx:%x\n", route,
                        pkg->port);
        }

        tb_queue_hotplug(tb, route, pkg->port, pkg->unplug);
}

static void tb_stop(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel;
        struct tb_tunnel *n;

        cancel_delayed_work(&tcm->remove_work);
        /* tunnels are only present after everything has been initialized */
        list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list) {
                /*
                 * DMA tunnels require the driver to be functional so we
                 * tear them down. Other protocol tunnels can be left
                 * intact.
                 */
                if (tb_tunnel_is_dma(tunnel))
                        tb_tunnel_deactivate(tunnel);
                tb_tunnel_free(tunnel);
        }
        tb_switch_remove(tb->root_switch);
        tcm->hotplug_active = false; /* signal tb_handle_hotplug to quit */
}

static int tb_scan_finalize_switch(struct device *dev, void *data)
{
        if (tb_is_switch(dev)) {
                struct tb_switch *sw = tb_to_switch(dev);

                /*
                 * If we found that the switch was already setup by the
                 * boot firmware, mark it as authorized now before we
                 * send uevent to userspace.
                 */
                if (sw->boot)
                        sw->authorized = 1;

                dev_set_uevent_suppress(dev, false);
                kobject_uevent(&dev->kobj, KOBJ_ADD);
                device_for_each_child(dev, NULL, tb_scan_finalize_switch);
        }

        return 0;
}

static int tb_start(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        int ret;

        tb->root_switch = tb_switch_alloc(tb, &tb->dev, 0);
        if (IS_ERR(tb->root_switch))
                return PTR_ERR(tb->root_switch);

        /*
         * ICM firmware upgrade needs running firmware and in native
         * mode that is not available so disable firmware upgrade of the
         * root switch.
         */
        tb->root_switch->no_nvm_upgrade = true;
        /* All USB4 routers support runtime PM */
        tb->root_switch->rpm = tb_switch_is_usb4(tb->root_switch);

        ret = tb_switch_configure(tb->root_switch);
        if (ret) {
                tb_switch_put(tb->root_switch);
                return ret;
        }

        /* Announce the switch to the world */
        ret = tb_switch_add(tb->root_switch);
        if (ret) {
                tb_switch_put(tb->root_switch);
                return ret;
        }

        /* Enable TMU if it is off */
        tb_switch_tmu_enable(tb->root_switch);
        /* Full scan to discover devices added before the driver was loaded. */
        tb_scan_switch(tb->root_switch);
        /* Find out tunnels created by the boot firmware */
        tb_discover_tunnels(tb->root_switch);
        /*
         * If the boot firmware did not create USB 3.x tunnels create them
         * now for the whole topology.
         */
        tb_create_usb3_tunnels(tb->root_switch);
        /* Add DP IN resources for the root switch */
        tb_add_dp_resources(tb->root_switch);
        /* Make the discovered switches available to the userspace */
        device_for_each_child(&tb->root_switch->dev, NULL,
                              tb_scan_finalize_switch);

        /* Allow tb_handle_hotplug to progress events */
        tcm->hotplug_active = true;
        return 0;
}

static int tb_suspend_noirq(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);

        tb_dbg(tb, "suspending...\n");
        tb_disconnect_and_release_dp(tb);
        tb_switch_suspend(tb->root_switch, false);
        tcm->hotplug_active = false; /* signal tb_handle_hotplug to quit */
        tb_dbg(tb, "suspend finished\n");

        return 0;
}

static void tb_restore_children(struct tb_switch *sw)
{
        struct tb_port *port;

        /* No need to restore if the router is already unplugged */
        if (sw->is_unplugged)
                return;

        if (tb_enable_tmu(sw))
                tb_sw_warn(sw, "failed to restore TMU configuration\n");

        tb_switch_for_each_port(sw, port) {
                if (!tb_port_has_remote(port) && !port->xdomain)
                        continue;

                if (port->remote) {
                        tb_switch_lane_bonding_enable(port->remote->sw);
                        tb_switch_configure_link(port->remote->sw);

                        tb_restore_children(port->remote->sw);
                } else if (port->xdomain) {
                        tb_port_configure_xdomain(port);
                }
        }
}

static int tb_resume_noirq(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel, *n;

        tb_dbg(tb, "resuming...\n");

        /* remove any pci devices the firmware might have setup */
        tb_switch_reset(tb->root_switch);

        tb_switch_resume(tb->root_switch);
        tb_free_invalid_tunnels(tb);
        tb_free_unplugged_children(tb->root_switch);
        tb_restore_children(tb->root_switch);
        list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list)
                tb_tunnel_restart(tunnel);
        if (!list_empty(&tcm->tunnel_list)) {
                /*
                 * the pcie links need some time to get going.
                 * 100ms works for me...
                 */
                tb_dbg(tb, "tunnels restarted, sleeping for 100ms\n");
                msleep(100);
        }
         /* Allow tb_handle_hotplug to progress events */
        tcm->hotplug_active = true;
        tb_dbg(tb, "resume finished\n");

        return 0;
}

static int tb_free_unplugged_xdomains(struct tb_switch *sw)
{
        struct tb_port *port;
        int ret = 0;

        tb_switch_for_each_port(sw, port) {
                if (tb_is_upstream_port(port))
                        continue;
                if (port->xdomain && port->xdomain->is_unplugged) {
                        tb_retimer_remove_all(port);
                        tb_xdomain_remove(port->xdomain);
                        tb_port_unconfigure_xdomain(port);
                        port->xdomain = NULL;
                        ret++;
                } else if (port->remote) {
                        ret += tb_free_unplugged_xdomains(port->remote->sw);
                }
        }

        return ret;
}

static int tb_freeze_noirq(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);

        tcm->hotplug_active = false;
        return 0;
}

static int tb_thaw_noirq(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);

        tcm->hotplug_active = true;
        return 0;
}

static void tb_complete(struct tb *tb)
{
        /*
         * Release any unplugged XDomains and if there is a case where
         * another domain is swapped in place of unplugged XDomain we
         * need to run another rescan.
         */
        mutex_lock(&tb->lock);
        if (tb_free_unplugged_xdomains(tb->root_switch))
                tb_scan_switch(tb->root_switch);
        mutex_unlock(&tb->lock);
}

static int tb_runtime_suspend(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);

        mutex_lock(&tb->lock);
        tb_switch_suspend(tb->root_switch, true);
        tcm->hotplug_active = false;
        mutex_unlock(&tb->lock);

        return 0;
}

static void tb_remove_work(struct work_struct *work)
{
        struct tb_cm *tcm = container_of(work, struct tb_cm, remove_work.work);
        struct tb *tb = tcm_to_tb(tcm);

        mutex_lock(&tb->lock);
        if (tb->root_switch) {
                tb_free_unplugged_children(tb->root_switch);
                tb_free_unplugged_xdomains(tb->root_switch);
        }
        mutex_unlock(&tb->lock);
}

static int tb_runtime_resume(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel, *n;

        mutex_lock(&tb->lock);
        tb_switch_resume(tb->root_switch);
        tb_free_invalid_tunnels(tb);
        tb_restore_children(tb->root_switch);
        list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list)
                tb_tunnel_restart(tunnel);
        tcm->hotplug_active = true;
        mutex_unlock(&tb->lock);

        /*
         * Schedule cleanup of any unplugged devices. Run this in a
         * separate thread to avoid possible deadlock if the device
         * removal runtime resumes the unplugged device.
         */
        queue_delayed_work(tb->wq, &tcm->remove_work, msecs_to_jiffies(50));
        return 0;
}

static const struct tb_cm_ops tb_cm_ops = {
        .start = tb_start,
        .stop = tb_stop,
        .suspend_noirq = tb_suspend_noirq,
        .resume_noirq = tb_resume_noirq,
        .freeze_noirq = tb_freeze_noirq,
        .thaw_noirq = tb_thaw_noirq,
        .complete = tb_complete,
        .runtime_suspend = tb_runtime_suspend,
        .runtime_resume = tb_runtime_resume,
        .handle_event = tb_handle_event,
        .disapprove_switch = tb_disconnect_pci,
        .approve_switch = tb_tunnel_pci,
        .approve_xdomain_paths = tb_approve_xdomain_paths,
        .disconnect_xdomain_paths = tb_disconnect_xdomain_paths,
};

/*
 * During suspend the Thunderbolt controller is reset and all PCIe
 * tunnels are lost. The NHI driver will try to reestablish all tunnels
 * during resume. This adds device links between the tunneled PCIe
 * downstream ports and the NHI so that the device core will make sure
 * NHI is resumed first before the rest.
 */
static void tb_apple_add_links(struct tb_nhi *nhi)
{
        struct pci_dev *upstream, *pdev;

        if (!x86_apple_machine)
                return;

        switch (nhi->pdev->device) {
        case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
        case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C:
        case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_2C_NHI:
        case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_4C_NHI:
                break;
        default:
                return;
        }

        upstream = pci_upstream_bridge(nhi->pdev);
        while (upstream) {
                if (!pci_is_pcie(upstream))
                        return;
                if (pci_pcie_type(upstream) == PCI_EXP_TYPE_UPSTREAM)
                        break;
                upstream = pci_upstream_bridge(upstream);
        }

        if (!upstream)
                return;

        /*
         * For each hotplug downstream port, create add device link
         * back to NHI so that PCIe tunnels can be re-established after
         * sleep.
         */
        for_each_pci_bridge(pdev, upstream->subordinate) {
                const struct device_link *link;

                if (!pci_is_pcie(pdev))
                        continue;
                if (pci_pcie_type(pdev) != PCI_EXP_TYPE_DOWNSTREAM ||
                    !pdev->is_hotplug_bridge)
                        continue;

                link = device_link_add(&pdev->dev, &nhi->pdev->dev,
                                       DL_FLAG_AUTOREMOVE_SUPPLIER |
                                       DL_FLAG_PM_RUNTIME);
                if (link) {
                        dev_dbg(&nhi->pdev->dev, "created link from %s\n",
                                dev_name(&pdev->dev));
                } else {
                        dev_warn(&nhi->pdev->dev, "device link creation from %s failed\n",
                                 dev_name(&pdev->dev));
                }
        }
}

struct tb *tb_probe(struct tb_nhi *nhi)
{
        struct tb_cm *tcm;
        struct tb *tb;

        tb = tb_domain_alloc(nhi, TB_TIMEOUT, sizeof(*tcm));
        if (!tb)
                return NULL;

        if (tb_acpi_may_tunnel_pcie())
                tb->security_level = TB_SECURITY_USER;
        else
                tb->security_level = TB_SECURITY_NOPCIE;

        tb->cm_ops = &tb_cm_ops;

        tcm = tb_priv(tb);
        INIT_LIST_HEAD(&tcm->tunnel_list);
        INIT_LIST_HEAD(&tcm->dp_resources);
        INIT_DELAYED_WORK(&tcm->remove_work, tb_remove_work);

        tb_dbg(tb, "using software connection manager\n");

        tb_apple_add_links(nhi);
        tb_acpi_add_links(nhi);

        return tb;
}