powerpc/fadump: Do not allow hot-remove memory from fadump reserved area.

[linux/fpc-iii.git] / drivers / thunderbolt / switch.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Thunderbolt Cactus Ridge driver - switch/port utility functions
 *
 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
 */

#include <linux/delay.h>
#include <linux/idr.h>
#include <linux/nvmem-provider.h>
#include <linux/pm_runtime.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include "tb.h"

/* Switch authorization from userspace is serialized by this lock */
static DEFINE_MUTEX(switch_lock);

/* Switch NVM support */

#define NVM_DEVID               0x05
#define NVM_VERSION             0x08
#define NVM_CSS                 0x10
#define NVM_FLASH_SIZE          0x45

#define NVM_MIN_SIZE            SZ_32K
#define NVM_MAX_SIZE            SZ_512K

static DEFINE_IDA(nvm_ida);

struct nvm_auth_status {
        struct list_head list;
        uuid_t uuid;
        u32 status;
};

/*
 * Hold NVM authentication failure status per switch This information
 * needs to stay around even when the switch gets power cycled so we
 * keep it separately.
 */
static LIST_HEAD(nvm_auth_status_cache);
static DEFINE_MUTEX(nvm_auth_status_lock);

static struct nvm_auth_status *__nvm_get_auth_status(const struct tb_switch *sw)
{
        struct nvm_auth_status *st;

        list_for_each_entry(st, &nvm_auth_status_cache, list) {
                if (uuid_equal(&st->uuid, sw->uuid))
                        return st;
        }

        return NULL;
}

static void nvm_get_auth_status(const struct tb_switch *sw, u32 *status)
{
        struct nvm_auth_status *st;

        mutex_lock(&nvm_auth_status_lock);
        st = __nvm_get_auth_status(sw);
        mutex_unlock(&nvm_auth_status_lock);

        *status = st ? st->status : 0;
}

static void nvm_set_auth_status(const struct tb_switch *sw, u32 status)
{
        struct nvm_auth_status *st;

        if (WARN_ON(!sw->uuid))
                return;

        mutex_lock(&nvm_auth_status_lock);
        st = __nvm_get_auth_status(sw);

        if (!st) {
                st = kzalloc(sizeof(*st), GFP_KERNEL);
                if (!st)
                        goto unlock;

                memcpy(&st->uuid, sw->uuid, sizeof(st->uuid));
                INIT_LIST_HEAD(&st->list);
                list_add_tail(&st->list, &nvm_auth_status_cache);
        }

        st->status = status;
unlock:
        mutex_unlock(&nvm_auth_status_lock);
}

static void nvm_clear_auth_status(const struct tb_switch *sw)
{
        struct nvm_auth_status *st;

        mutex_lock(&nvm_auth_status_lock);
        st = __nvm_get_auth_status(sw);
        if (st) {
                list_del(&st->list);
                kfree(st);
        }
        mutex_unlock(&nvm_auth_status_lock);
}

static int nvm_validate_and_write(struct tb_switch *sw)
{
        unsigned int image_size, hdr_size;
        const u8 *buf = sw->nvm->buf;
        u16 ds_size;
        int ret;

        if (!buf)
                return -EINVAL;

        image_size = sw->nvm->buf_data_size;
        if (image_size < NVM_MIN_SIZE || image_size > NVM_MAX_SIZE)
                return -EINVAL;

        /*
         * FARB pointer must point inside the image and must at least
         * contain parts of the digital section we will be reading here.
         */
        hdr_size = (*(u32 *)buf) & 0xffffff;
        if (hdr_size + NVM_DEVID + 2 >= image_size)
                return -EINVAL;

        /* Digital section start should be aligned to 4k page */
        if (!IS_ALIGNED(hdr_size, SZ_4K))
                return -EINVAL;

        /*
         * Read digital section size and check that it also fits inside
         * the image.
         */
        ds_size = *(u16 *)(buf + hdr_size);
        if (ds_size >= image_size)
                return -EINVAL;

        if (!sw->safe_mode) {
                u16 device_id;

                /*
                 * Make sure the device ID in the image matches the one
                 * we read from the switch config space.
                 */
                device_id = *(u16 *)(buf + hdr_size + NVM_DEVID);
                if (device_id != sw->config.device_id)
                        return -EINVAL;

                if (sw->generation < 3) {
                        /* Write CSS headers first */
                        ret = dma_port_flash_write(sw->dma_port,
                                DMA_PORT_CSS_ADDRESS, buf + NVM_CSS,
                                DMA_PORT_CSS_MAX_SIZE);
                        if (ret)
                                return ret;
                }

                /* Skip headers in the image */
                buf += hdr_size;
                image_size -= hdr_size;
        }

        return dma_port_flash_write(sw->dma_port, 0, buf, image_size);
}

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

        /*
         * Root switch NVM upgrade requires that we disconnect the
         * existing paths first (in case it is not in safe mode
         * already).
         */
        if (!sw->safe_mode) {
                ret = tb_domain_disconnect_all_paths(sw->tb);
                if (ret)
                        return ret;
                /*
                 * The host controller goes away pretty soon after this if
                 * everything goes well so getting timeout is expected.
                 */
                ret = dma_port_flash_update_auth(sw->dma_port);
                return ret == -ETIMEDOUT ? 0 : ret;
        }

        /*
         * From safe mode we can get out by just power cycling the
         * switch.
         */
        dma_port_power_cycle(sw->dma_port);
        return 0;
}

static int nvm_authenticate_device(struct tb_switch *sw)
{
        int ret, retries = 10;

        ret = dma_port_flash_update_auth(sw->dma_port);
        if (ret && ret != -ETIMEDOUT)
                return ret;

        /*
         * Poll here for the authentication status. It takes some time
         * for the device to respond (we get timeout for a while). Once
         * we get response the device needs to be power cycled in order
         * to the new NVM to be taken into use.
         */
        do {
                u32 status;

                ret = dma_port_flash_update_auth_status(sw->dma_port, &status);
                if (ret < 0 && ret != -ETIMEDOUT)
                        return ret;
                if (ret > 0) {
                        if (status) {
                                tb_sw_warn(sw, "failed to authenticate NVM\n");
                                nvm_set_auth_status(sw, status);
                        }

                        tb_sw_info(sw, "power cycling the switch now\n");
                        dma_port_power_cycle(sw->dma_port);
                        return 0;
                }

                msleep(500);
        } while (--retries);

        return -ETIMEDOUT;
}

static int tb_switch_nvm_read(void *priv, unsigned int offset, void *val,
                              size_t bytes)
{
        struct tb_switch *sw = priv;
        int ret;

        pm_runtime_get_sync(&sw->dev);
        ret = dma_port_flash_read(sw->dma_port, offset, val, bytes);
        pm_runtime_mark_last_busy(&sw->dev);
        pm_runtime_put_autosuspend(&sw->dev);

        return ret;
}

static int tb_switch_nvm_write(void *priv, unsigned int offset, void *val,
                               size_t bytes)
{
        struct tb_switch *sw = priv;
        int ret = 0;

        if (mutex_lock_interruptible(&switch_lock))
                return -ERESTARTSYS;

        /*
         * Since writing the NVM image might require some special steps,
         * for example when CSS headers are written, we cache the image
         * locally here and handle the special cases when the user asks
         * us to authenticate the image.
         */
        if (!sw->nvm->buf) {
                sw->nvm->buf = vmalloc(NVM_MAX_SIZE);
                if (!sw->nvm->buf) {
                        ret = -ENOMEM;
                        goto unlock;
                }
        }

        sw->nvm->buf_data_size = offset + bytes;
        memcpy(sw->nvm->buf + offset, val, bytes);

unlock:
        mutex_unlock(&switch_lock);

        return ret;
}

static struct nvmem_device *register_nvmem(struct tb_switch *sw, int id,
                                           size_t size, bool active)
{
        struct nvmem_config config;

        memset(&config, 0, sizeof(config));

        if (active) {
                config.name = "nvm_active";
                config.reg_read = tb_switch_nvm_read;
                config.read_only = true;
        } else {
                config.name = "nvm_non_active";
                config.reg_write = tb_switch_nvm_write;
                config.root_only = true;
        }

        config.id = id;
        config.stride = 4;
        config.word_size = 4;
        config.size = size;
        config.dev = &sw->dev;
        config.owner = THIS_MODULE;
        config.priv = sw;

        return nvmem_register(&config);
}

static int tb_switch_nvm_add(struct tb_switch *sw)
{
        struct nvmem_device *nvm_dev;
        struct tb_switch_nvm *nvm;
        u32 val;
        int ret;

        if (!sw->dma_port)
                return 0;

        nvm = kzalloc(sizeof(*nvm), GFP_KERNEL);
        if (!nvm)
                return -ENOMEM;

        nvm->id = ida_simple_get(&nvm_ida, 0, 0, GFP_KERNEL);

        /*
         * If the switch is in safe-mode the only accessible portion of
         * the NVM is the non-active one where userspace is expected to
         * write new functional NVM.
         */
        if (!sw->safe_mode) {
                u32 nvm_size, hdr_size;

                ret = dma_port_flash_read(sw->dma_port, NVM_FLASH_SIZE, &val,
                                          sizeof(val));
                if (ret)
                        goto err_ida;

                hdr_size = sw->generation < 3 ? SZ_8K : SZ_16K;
                nvm_size = (SZ_1M << (val & 7)) / 8;
                nvm_size = (nvm_size - hdr_size) / 2;

                ret = dma_port_flash_read(sw->dma_port, NVM_VERSION, &val,
                                          sizeof(val));
                if (ret)
                        goto err_ida;

                nvm->major = val >> 16;
                nvm->minor = val >> 8;

                nvm_dev = register_nvmem(sw, nvm->id, nvm_size, true);
                if (IS_ERR(nvm_dev)) {
                        ret = PTR_ERR(nvm_dev);
                        goto err_ida;
                }
                nvm->active = nvm_dev;
        }

        nvm_dev = register_nvmem(sw, nvm->id, NVM_MAX_SIZE, false);
        if (IS_ERR(nvm_dev)) {
                ret = PTR_ERR(nvm_dev);
                goto err_nvm_active;
        }
        nvm->non_active = nvm_dev;

        mutex_lock(&switch_lock);
        sw->nvm = nvm;
        mutex_unlock(&switch_lock);

        return 0;

err_nvm_active:
        if (nvm->active)
                nvmem_unregister(nvm->active);
err_ida:
        ida_simple_remove(&nvm_ida, nvm->id);
        kfree(nvm);

        return ret;
}

static void tb_switch_nvm_remove(struct tb_switch *sw)
{
        struct tb_switch_nvm *nvm;

        mutex_lock(&switch_lock);
        nvm = sw->nvm;
        sw->nvm = NULL;
        mutex_unlock(&switch_lock);

        if (!nvm)
                return;

        /* Remove authentication status in case the switch is unplugged */
        if (!nvm->authenticating)
                nvm_clear_auth_status(sw);

        nvmem_unregister(nvm->non_active);
        if (nvm->active)
                nvmem_unregister(nvm->active);
        ida_simple_remove(&nvm_ida, nvm->id);
        vfree(nvm->buf);
        kfree(nvm);
}

/* port utility functions */

static const char *tb_port_type(struct tb_regs_port_header *port)
{
        switch (port->type >> 16) {
        case 0:
                switch ((u8) port->type) {
                case 0:
                        return "Inactive";
                case 1:
                        return "Port";
                case 2:
                        return "NHI";
                default:
                        return "unknown";
                }
        case 0x2:
                return "Ethernet";
        case 0x8:
                return "SATA";
        case 0xe:
                return "DP/HDMI";
        case 0x10:
                return "PCIe";
        case 0x20:
                return "USB";
        default:
                return "unknown";
        }
}

static void tb_dump_port(struct tb *tb, struct tb_regs_port_header *port)
{
        tb_info(tb,
                " Port %d: %x:%x (Revision: %d, TB Version: %d, Type: %s (%#x))\n",
                port->port_number, port->vendor_id, port->device_id,
                port->revision, port->thunderbolt_version, tb_port_type(port),
                port->type);
        tb_info(tb, "  Max hop id (in/out): %d/%d\n",
                port->max_in_hop_id, port->max_out_hop_id);
        tb_info(tb, "  Max counters: %d\n", port->max_counters);
        tb_info(tb, "  NFC Credits: %#x\n", port->nfc_credits);
}

/**
 * tb_port_state() - get connectedness state of a port
 *
 * The port must have a TB_CAP_PHY (i.e. it should be a real port).
 *
 * Return: Returns an enum tb_port_state on success or an error code on failure.
 */
static int tb_port_state(struct tb_port *port)
{
        struct tb_cap_phy phy;
        int res;
        if (port->cap_phy == 0) {
                tb_port_WARN(port, "does not have a PHY\n");
                return -EINVAL;
        }
        res = tb_port_read(port, &phy, TB_CFG_PORT, port->cap_phy, 2);
        if (res)
                return res;
        return phy.state;
}

/**
 * tb_wait_for_port() - wait for a port to become ready
 *
 * Wait up to 1 second for a port to reach state TB_PORT_UP. If
 * wait_if_unplugged is set then we also wait if the port is in state
 * TB_PORT_UNPLUGGED (it takes a while for the device to be registered after
 * switch resume). Otherwise we only wait if a device is registered but the link
 * has not yet been established.
 *
 * Return: Returns an error code on failure. Returns 0 if the port is not
 * connected or failed to reach state TB_PORT_UP within one second. Returns 1
 * if the port is connected and in state TB_PORT_UP.
 */
int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged)
{
        int retries = 10;
        int state;
        if (!port->cap_phy) {
                tb_port_WARN(port, "does not have PHY\n");
                return -EINVAL;
        }
        if (tb_is_upstream_port(port)) {
                tb_port_WARN(port, "is the upstream port\n");
                return -EINVAL;
        }

        while (retries--) {
                state = tb_port_state(port);
                if (state < 0)
                        return state;
                if (state == TB_PORT_DISABLED) {
                        tb_port_info(port, "is disabled (state: 0)\n");
                        return 0;
                }
                if (state == TB_PORT_UNPLUGGED) {
                        if (wait_if_unplugged) {
                                /* used during resume */
                                tb_port_info(port,
                                             "is unplugged (state: 7), retrying...\n");
                                msleep(100);
                                continue;
                        }
                        tb_port_info(port, "is unplugged (state: 7)\n");
                        return 0;
                }
                if (state == TB_PORT_UP) {
                        tb_port_info(port,
                                     "is connected, link is up (state: 2)\n");
                        return 1;
                }

                /*
                 * After plug-in the state is TB_PORT_CONNECTING. Give it some
                 * time.
                 */
                tb_port_info(port,
                             "is connected, link is not up (state: %d), retrying...\n",
                             state);
                msleep(100);
        }
        tb_port_warn(port,
                     "failed to reach state TB_PORT_UP. Ignoring port...\n");
        return 0;
}

/**
 * tb_port_add_nfc_credits() - add/remove non flow controlled credits to port
 *
 * Change the number of NFC credits allocated to @port by @credits. To remove
 * NFC credits pass a negative amount of credits.
 *
 * Return: Returns 0 on success or an error code on failure.
 */
int tb_port_add_nfc_credits(struct tb_port *port, int credits)
{
        if (credits == 0)
                return 0;
        tb_port_info(port,
                     "adding %#x NFC credits (%#x -> %#x)",
                     credits,
                     port->config.nfc_credits,
                     port->config.nfc_credits + credits);
        port->config.nfc_credits += credits;
        return tb_port_write(port, &port->config.nfc_credits,
                             TB_CFG_PORT, 4, 1);
}

/**
 * tb_port_clear_counter() - clear a counter in TB_CFG_COUNTER
 *
 * Return: Returns 0 on success or an error code on failure.
 */
int tb_port_clear_counter(struct tb_port *port, int counter)
{
        u32 zero[3] = { 0, 0, 0 };
        tb_port_info(port, "clearing counter %d\n", counter);
        return tb_port_write(port, zero, TB_CFG_COUNTERS, 3 * counter, 3);
}

/**
 * tb_init_port() - initialize a port
 *
 * This is a helper method for tb_switch_alloc. Does not check or initialize
 * any downstream switches.
 *
 * Return: Returns 0 on success or an error code on failure.
 */
static int tb_init_port(struct tb_port *port)
{
        int res;
        int cap;

        res = tb_port_read(port, &port->config, TB_CFG_PORT, 0, 8);
        if (res)
                return res;

        /* Port 0 is the switch itself and has no PHY. */
        if (port->config.type == TB_TYPE_PORT && port->port != 0) {
                cap = tb_port_find_cap(port, TB_PORT_CAP_PHY);

                if (cap > 0)
                        port->cap_phy = cap;
                else
                        tb_port_WARN(port, "non switch port without a PHY\n");
        }

        tb_dump_port(port->sw->tb, &port->config);

        /* TODO: Read dual link port, DP port and more from EEPROM. */
        return 0;

}

/* switch utility functions */

static void tb_dump_switch(struct tb *tb, struct tb_regs_switch_header *sw)
{
        tb_info(tb,
                " Switch: %x:%x (Revision: %d, TB Version: %d)\n",
                sw->vendor_id, sw->device_id, sw->revision,
                sw->thunderbolt_version);
        tb_info(tb, "  Max Port Number: %d\n", sw->max_port_number);
        tb_info(tb, "  Config:\n");
        tb_info(tb,
                "   Upstream Port Number: %d Depth: %d Route String: %#llx Enabled: %d, PlugEventsDelay: %dms\n",
                sw->upstream_port_number, sw->depth,
                (((u64) sw->route_hi) << 32) | sw->route_lo,
                sw->enabled, sw->plug_events_delay);
        tb_info(tb,
                "   unknown1: %#x unknown4: %#x\n",
                sw->__unknown1, sw->__unknown4);
}

/**
 * reset_switch() - reconfigure route, enable and send TB_CFG_PKG_RESET
 *
 * Return: Returns 0 on success or an error code on failure.
 */
int tb_switch_reset(struct tb *tb, u64 route)
{
        struct tb_cfg_result res;
        struct tb_regs_switch_header header = {
                header.route_hi = route >> 32,
                header.route_lo = route,
                header.enabled = true,
        };
        tb_info(tb, "resetting switch at %llx\n", route);
        res.err = tb_cfg_write(tb->ctl, ((u32 *) &header) + 2, route,
                        0, 2, 2, 2);
        if (res.err)
                return res.err;
        res = tb_cfg_reset(tb->ctl, route, TB_CFG_DEFAULT_TIMEOUT);
        if (res.err > 0)
                return -EIO;
        return res.err;
}

struct tb_switch *get_switch_at_route(struct tb_switch *sw, u64 route)
{
        u8 next_port = route; /*
                               * Routes use a stride of 8 bits,
                               * eventhough a port index has 6 bits at most.
                               * */
        if (route == 0)
                return sw;
        if (next_port > sw->config.max_port_number)
                return NULL;
        if (tb_is_upstream_port(&sw->ports[next_port]))
                return NULL;
        if (!sw->ports[next_port].remote)
                return NULL;
        return get_switch_at_route(sw->ports[next_port].remote->sw,
                                   route >> TB_ROUTE_SHIFT);
}

/**
 * tb_plug_events_active() - enable/disable plug events on a switch
 *
 * Also configures a sane plug_events_delay of 255ms.
 *
 * Return: Returns 0 on success or an error code on failure.
 */
static int tb_plug_events_active(struct tb_switch *sw, bool active)
{
        u32 data;
        int res;

        if (!sw->config.enabled)
                return 0;

        sw->config.plug_events_delay = 0xff;
        res = tb_sw_write(sw, ((u32 *) &sw->config) + 4, TB_CFG_SWITCH, 4, 1);
        if (res)
                return res;

        res = tb_sw_read(sw, &data, TB_CFG_SWITCH, sw->cap_plug_events + 1, 1);
        if (res)
                return res;

        if (active) {
                data = data & 0xFFFFFF83;
                switch (sw->config.device_id) {
                case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
                case PCI_DEVICE_ID_INTEL_EAGLE_RIDGE:
                case PCI_DEVICE_ID_INTEL_PORT_RIDGE:
                        break;
                default:
                        data |= 4;
                }
        } else {
                data = data | 0x7c;
        }
        return tb_sw_write(sw, &data, TB_CFG_SWITCH,
                           sw->cap_plug_events + 1, 1);
}

static ssize_t authorized_show(struct device *dev,
                               struct device_attribute *attr,
                               char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%u\n", sw->authorized);
}

static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
{
        int ret = -EINVAL;

        if (mutex_lock_interruptible(&switch_lock))
                return -ERESTARTSYS;

        if (sw->authorized)
                goto unlock;

        /*
         * Make sure there is no PCIe rescan ongoing when a new PCIe
         * tunnel is created. Otherwise the PCIe rescan code might find
         * the new tunnel too early.
         */
        pci_lock_rescan_remove();
        pm_runtime_get_sync(&sw->dev);

        switch (val) {
        /* Approve switch */
        case 1:
                if (sw->key)
                        ret = tb_domain_approve_switch_key(sw->tb, sw);
                else
                        ret = tb_domain_approve_switch(sw->tb, sw);
                break;

        /* Challenge switch */
        case 2:
                if (sw->key)
                        ret = tb_domain_challenge_switch_key(sw->tb, sw);
                break;

        default:
                break;
        }

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

        if (!ret) {
                sw->authorized = val;
                /* Notify status change to the userspace */
                kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
        }

unlock:
        mutex_unlock(&switch_lock);
        return ret;
}

static ssize_t authorized_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct tb_switch *sw = tb_to_switch(dev);
        unsigned int val;
        ssize_t ret;

        ret = kstrtouint(buf, 0, &val);
        if (ret)
                return ret;
        if (val > 2)
                return -EINVAL;

        ret = tb_switch_set_authorized(sw, val);

        return ret ? ret : count;
}
static DEVICE_ATTR_RW(authorized);

static ssize_t boot_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%u\n", sw->boot);
}
static DEVICE_ATTR_RO(boot);

static ssize_t device_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%#x\n", sw->device);
}
static DEVICE_ATTR_RO(device);

static ssize_t
device_name_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%s\n", sw->device_name ? sw->device_name : "");
}
static DEVICE_ATTR_RO(device_name);

static ssize_t key_show(struct device *dev, struct device_attribute *attr,
                        char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);
        ssize_t ret;

        if (mutex_lock_interruptible(&switch_lock))
                return -ERESTARTSYS;

        if (sw->key)
                ret = sprintf(buf, "%*phN\n", TB_SWITCH_KEY_SIZE, sw->key);
        else
                ret = sprintf(buf, "\n");

        mutex_unlock(&switch_lock);
        return ret;
}

static ssize_t key_store(struct device *dev, struct device_attribute *attr,
                         const char *buf, size_t count)
{
        struct tb_switch *sw = tb_to_switch(dev);
        u8 key[TB_SWITCH_KEY_SIZE];
        ssize_t ret = count;
        bool clear = false;

        if (!strcmp(buf, "\n"))
                clear = true;
        else if (hex2bin(key, buf, sizeof(key)))
                return -EINVAL;

        if (mutex_lock_interruptible(&switch_lock))
                return -ERESTARTSYS;

        if (sw->authorized) {
                ret = -EBUSY;
        } else {
                kfree(sw->key);
                if (clear) {
                        sw->key = NULL;
                } else {
                        sw->key = kmemdup(key, sizeof(key), GFP_KERNEL);
                        if (!sw->key)
                                ret = -ENOMEM;
                }
        }

        mutex_unlock(&switch_lock);
        return ret;
}
static DEVICE_ATTR(key, 0600, key_show, key_store);

static void nvm_authenticate_start(struct tb_switch *sw)
{
        struct pci_dev *root_port;

        /*
         * During host router NVM upgrade we should not allow root port to
         * go into D3cold because some root ports cannot trigger PME
         * itself. To be on the safe side keep the root port in D0 during
         * the whole upgrade process.
         */
        root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
        if (root_port)
                pm_runtime_get_noresume(&root_port->dev);
}

static void nvm_authenticate_complete(struct tb_switch *sw)
{
        struct pci_dev *root_port;

        root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
        if (root_port)
                pm_runtime_put(&root_port->dev);
}

static ssize_t nvm_authenticate_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);
        u32 status;

        nvm_get_auth_status(sw, &status);
        return sprintf(buf, "%#x\n", status);
}

static ssize_t nvm_authenticate_store(struct device *dev,
        struct device_attribute *attr, const char *buf, size_t count)
{
        struct tb_switch *sw = tb_to_switch(dev);
        bool val;
        int ret;

        if (mutex_lock_interruptible(&switch_lock))
                return -ERESTARTSYS;

        /* If NVMem devices are not yet added */
        if (!sw->nvm) {
                ret = -EAGAIN;
                goto exit_unlock;
        }

        ret = kstrtobool(buf, &val);
        if (ret)
                goto exit_unlock;

        /* Always clear the authentication status */
        nvm_clear_auth_status(sw);

        if (val) {
                if (!sw->nvm->buf) {
                        ret = -EINVAL;
                        goto exit_unlock;
                }

                pm_runtime_get_sync(&sw->dev);
                ret = nvm_validate_and_write(sw);
                if (ret) {
                        pm_runtime_mark_last_busy(&sw->dev);
                        pm_runtime_put_autosuspend(&sw->dev);
                        goto exit_unlock;
                }

                sw->nvm->authenticating = true;

                if (!tb_route(sw)) {
                        /*
                         * Keep root port from suspending as long as the
                         * NVM upgrade process is running.
                         */
                        nvm_authenticate_start(sw);
                        ret = nvm_authenticate_host(sw);
                        if (ret)
                                nvm_authenticate_complete(sw);
                } else {
                        ret = nvm_authenticate_device(sw);
                }
                pm_runtime_mark_last_busy(&sw->dev);
                pm_runtime_put_autosuspend(&sw->dev);
        }

exit_unlock:
        mutex_unlock(&switch_lock);

        if (ret)
                return ret;
        return count;
}
static DEVICE_ATTR_RW(nvm_authenticate);

static ssize_t nvm_version_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);
        int ret;

        if (mutex_lock_interruptible(&switch_lock))
                return -ERESTARTSYS;

        if (sw->safe_mode)
                ret = -ENODATA;
        else if (!sw->nvm)
                ret = -EAGAIN;
        else
                ret = sprintf(buf, "%x.%x\n", sw->nvm->major, sw->nvm->minor);

        mutex_unlock(&switch_lock);

        return ret;
}
static DEVICE_ATTR_RO(nvm_version);

static ssize_t vendor_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%#x\n", sw->vendor);
}
static DEVICE_ATTR_RO(vendor);

static ssize_t
vendor_name_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%s\n", sw->vendor_name ? sw->vendor_name : "");
}
static DEVICE_ATTR_RO(vendor_name);

static ssize_t unique_id_show(struct device *dev, struct device_attribute *attr,
                              char *buf)
{
        struct tb_switch *sw = tb_to_switch(dev);

        return sprintf(buf, "%pUb\n", sw->uuid);
}
static DEVICE_ATTR_RO(unique_id);

static struct attribute *switch_attrs[] = {
        &dev_attr_authorized.attr,
        &dev_attr_boot.attr,
        &dev_attr_device.attr,
        &dev_attr_device_name.attr,
        &dev_attr_key.attr,
        &dev_attr_nvm_authenticate.attr,
        &dev_attr_nvm_version.attr,
        &dev_attr_vendor.attr,
        &dev_attr_vendor_name.attr,
        &dev_attr_unique_id.attr,
        NULL,
};

static umode_t switch_attr_is_visible(struct kobject *kobj,
                                      struct attribute *attr, int n)
{
        struct device *dev = container_of(kobj, struct device, kobj);
        struct tb_switch *sw = tb_to_switch(dev);

        if (attr == &dev_attr_key.attr) {
                if (tb_route(sw) &&
                    sw->tb->security_level == TB_SECURITY_SECURE &&
                    sw->security_level == TB_SECURITY_SECURE)
                        return attr->mode;
                return 0;
        } else if (attr == &dev_attr_nvm_authenticate.attr ||
                   attr == &dev_attr_nvm_version.attr) {
                if (sw->dma_port)
                        return attr->mode;
                return 0;
        } else if (attr == &dev_attr_boot.attr) {
                if (tb_route(sw))
                        return attr->mode;
                return 0;
        }

        return sw->safe_mode ? 0 : attr->mode;
}

static struct attribute_group switch_group = {
        .is_visible = switch_attr_is_visible,
        .attrs = switch_attrs,
};

static const struct attribute_group *switch_groups[] = {
        &switch_group,
        NULL,
};

static void tb_switch_release(struct device *dev)
{
        struct tb_switch *sw = tb_to_switch(dev);

        dma_port_free(sw->dma_port);

        kfree(sw->uuid);
        kfree(sw->device_name);
        kfree(sw->vendor_name);
        kfree(sw->ports);
        kfree(sw->drom);
        kfree(sw->key);
        kfree(sw);
}

/*
 * Currently only need to provide the callbacks. Everything else is handled
 * in the connection manager.
 */
static int __maybe_unused tb_switch_runtime_suspend(struct device *dev)
{
        return 0;
}

static int __maybe_unused tb_switch_runtime_resume(struct device *dev)
{
        return 0;
}

static const struct dev_pm_ops tb_switch_pm_ops = {
        SET_RUNTIME_PM_OPS(tb_switch_runtime_suspend, tb_switch_runtime_resume,
                           NULL)
};

struct device_type tb_switch_type = {
        .name = "thunderbolt_device",
        .release = tb_switch_release,
        .pm = &tb_switch_pm_ops,
};

static int tb_switch_get_generation(struct tb_switch *sw)
{
        switch (sw->config.device_id) {
        case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
        case PCI_DEVICE_ID_INTEL_EAGLE_RIDGE:
        case PCI_DEVICE_ID_INTEL_LIGHT_PEAK:
        case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_2C:
        case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C:
        case PCI_DEVICE_ID_INTEL_PORT_RIDGE:
        case PCI_DEVICE_ID_INTEL_REDWOOD_RIDGE_2C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_REDWOOD_RIDGE_4C_BRIDGE:
                return 1;

        case PCI_DEVICE_ID_INTEL_WIN_RIDGE_2C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_2C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_4C_BRIDGE:
                return 2;

        case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_LP_BRIDGE:
        case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_2C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_4C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_2C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_4C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_2C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_4C_BRIDGE:
        case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_DD_BRIDGE:
                return 3;

        default:
                /*
                 * For unknown switches assume generation to be 1 to be
                 * on the safe side.
                 */
                tb_sw_warn(sw, "unsupported switch device id %#x\n",
                           sw->config.device_id);
                return 1;
        }
}

/**
 * tb_switch_alloc() - allocate a switch
 * @tb: Pointer to the owning domain
 * @parent: Parent device for this switch
 * @route: Route string for this switch
 *
 * Allocates and initializes a switch. Will not upload configuration to
 * the switch. For that you need to call tb_switch_configure()
 * separately. The returned switch should be released by calling
 * tb_switch_put().
 *
 * Return: Pointer to the allocated switch or %NULL in case of failure
 */
struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
                                  u64 route)
{
        int i;
        int cap;
        struct tb_switch *sw;
        int upstream_port = tb_cfg_get_upstream_port(tb->ctl, route);
        if (upstream_port < 0)
                return NULL;

        sw = kzalloc(sizeof(*sw), GFP_KERNEL);
        if (!sw)
                return NULL;

        sw->tb = tb;
        if (tb_cfg_read(tb->ctl, &sw->config, route, 0, TB_CFG_SWITCH, 0, 5))
                goto err_free_sw_ports;

        tb_info(tb, "current switch config:\n");
        tb_dump_switch(tb, &sw->config);

        /* configure switch */
        sw->config.upstream_port_number = upstream_port;
        sw->config.depth = tb_route_length(route);
        sw->config.route_lo = route;
        sw->config.route_hi = route >> 32;
        sw->config.enabled = 0;

        /* initialize ports */
        sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),
                                GFP_KERNEL);
        if (!sw->ports)
                goto err_free_sw_ports;

        for (i = 0; i <= sw->config.max_port_number; i++) {
                /* minimum setup for tb_find_cap and tb_drom_read to work */
                sw->ports[i].sw = sw;
                sw->ports[i].port = i;
        }

        sw->generation = tb_switch_get_generation(sw);

        cap = tb_switch_find_vse_cap(sw, TB_VSE_CAP_PLUG_EVENTS);
        if (cap < 0) {
                tb_sw_warn(sw, "cannot find TB_VSE_CAP_PLUG_EVENTS aborting\n");
                goto err_free_sw_ports;
        }
        sw->cap_plug_events = cap;

        /* Root switch is always authorized */
        if (!route)
                sw->authorized = true;

        device_initialize(&sw->dev);
        sw->dev.parent = parent;
        sw->dev.bus = &tb_bus_type;
        sw->dev.type = &tb_switch_type;
        sw->dev.groups = switch_groups;
        dev_set_name(&sw->dev, "%u-%llx", tb->index, tb_route(sw));

        return sw;

err_free_sw_ports:
        kfree(sw->ports);
        kfree(sw);

        return NULL;
}

/**
 * tb_switch_alloc_safe_mode() - allocate a switch that is in safe mode
 * @tb: Pointer to the owning domain
 * @parent: Parent device for this switch
 * @route: Route string for this switch
 *
 * This creates a switch in safe mode. This means the switch pretty much
 * lacks all capabilities except DMA configuration port before it is
 * flashed with a valid NVM firmware.
 *
 * The returned switch must be released by calling tb_switch_put().
 *
 * Return: Pointer to the allocated switch or %NULL in case of failure
 */
struct tb_switch *
tb_switch_alloc_safe_mode(struct tb *tb, struct device *parent, u64 route)
{
        struct tb_switch *sw;

        sw = kzalloc(sizeof(*sw), GFP_KERNEL);
        if (!sw)
                return NULL;

        sw->tb = tb;
        sw->config.depth = tb_route_length(route);
        sw->config.route_hi = upper_32_bits(route);
        sw->config.route_lo = lower_32_bits(route);
        sw->safe_mode = true;

        device_initialize(&sw->dev);
        sw->dev.parent = parent;
        sw->dev.bus = &tb_bus_type;
        sw->dev.type = &tb_switch_type;
        sw->dev.groups = switch_groups;
        dev_set_name(&sw->dev, "%u-%llx", tb->index, tb_route(sw));

        return sw;
}

/**
 * tb_switch_configure() - Uploads configuration to the switch
 * @sw: Switch to configure
 *
 * Call this function before the switch is added to the system. It will
 * upload configuration to the switch and makes it available for the
 * connection manager to use.
 *
 * Return: %0 in case of success and negative errno in case of failure
 */
int tb_switch_configure(struct tb_switch *sw)
{
        struct tb *tb = sw->tb;
        u64 route;
        int ret;

        route = tb_route(sw);
        tb_info(tb,
                "initializing Switch at %#llx (depth: %d, up port: %d)\n",
                route, tb_route_length(route), sw->config.upstream_port_number);

        if (sw->config.vendor_id != PCI_VENDOR_ID_INTEL)
                tb_sw_warn(sw, "unknown switch vendor id %#x\n",
                           sw->config.vendor_id);

        sw->config.enabled = 1;

        /* upload configuration */
        ret = tb_sw_write(sw, 1 + (u32 *)&sw->config, TB_CFG_SWITCH, 1, 3);
        if (ret)
                return ret;

        return tb_plug_events_active(sw, true);
}

static void tb_switch_set_uuid(struct tb_switch *sw)
{
        u32 uuid[4];
        int cap;

        if (sw->uuid)
                return;

        /*
         * The newer controllers include fused UUID as part of link
         * controller specific registers
         */
        cap = tb_switch_find_vse_cap(sw, TB_VSE_CAP_LINK_CONTROLLER);
        if (cap > 0) {
                tb_sw_read(sw, uuid, TB_CFG_SWITCH, cap + 3, 4);
        } else {
                /*
                 * ICM generates UUID based on UID and fills the upper
                 * two words with ones. This is not strictly following
                 * UUID format but we want to be compatible with it so
                 * we do the same here.
                 */
                uuid[0] = sw->uid & 0xffffffff;
                uuid[1] = (sw->uid >> 32) & 0xffffffff;
                uuid[2] = 0xffffffff;
                uuid[3] = 0xffffffff;
        }

        sw->uuid = kmemdup(uuid, sizeof(uuid), GFP_KERNEL);
}

static int tb_switch_add_dma_port(struct tb_switch *sw)
{
        u32 status;
        int ret;

        switch (sw->generation) {
        case 3:
                break;

        case 2:
                /* Only root switch can be upgraded */
                if (tb_route(sw))
                        return 0;
                break;

        default:
                /*
                 * DMA port is the only thing available when the switch
                 * is in safe mode.
                 */
                if (!sw->safe_mode)
                        return 0;
                break;
        }

        if (sw->no_nvm_upgrade)
                return 0;

        sw->dma_port = dma_port_alloc(sw);
        if (!sw->dma_port)
                return 0;

        /*
         * Check status of the previous flash authentication. If there
         * is one we need to power cycle the switch in any case to make
         * it functional again.
         */
        ret = dma_port_flash_update_auth_status(sw->dma_port, &status);
        if (ret <= 0)
                return ret;

        /* Now we can allow root port to suspend again */
        if (!tb_route(sw))
                nvm_authenticate_complete(sw);

        if (status) {
                tb_sw_info(sw, "switch flash authentication failed\n");
                tb_switch_set_uuid(sw);
                nvm_set_auth_status(sw, status);
        }

        tb_sw_info(sw, "power cycling the switch now\n");
        dma_port_power_cycle(sw->dma_port);

        /*
         * We return error here which causes the switch adding failure.
         * It should appear back after power cycle is complete.
         */
        return -ESHUTDOWN;
}

/**
 * tb_switch_add() - Add a switch to the domain
 * @sw: Switch to add
 *
 * This is the last step in adding switch to the domain. It will read
 * identification information from DROM and initializes ports so that
 * they can be used to connect other switches. The switch will be
 * exposed to the userspace when this function successfully returns. To
 * remove and release the switch, call tb_switch_remove().
 *
 * Return: %0 in case of success and negative errno in case of failure
 */
int tb_switch_add(struct tb_switch *sw)
{
        int i, ret;

        /*
         * Initialize DMA control port now before we read DROM. Recent
         * host controllers have more complete DROM on NVM that includes
         * vendor and model identification strings which we then expose
         * to the userspace. NVM can be accessed through DMA
         * configuration based mailbox.
         */
        ret = tb_switch_add_dma_port(sw);
        if (ret)
                return ret;

        if (!sw->safe_mode) {
                /* read drom */
                ret = tb_drom_read(sw);
                if (ret) {
                        tb_sw_warn(sw, "tb_eeprom_read_rom failed\n");
                        return ret;
                }
                tb_sw_info(sw, "uid: %#llx\n", sw->uid);

                tb_switch_set_uuid(sw);

                for (i = 0; i <= sw->config.max_port_number; i++) {
                        if (sw->ports[i].disabled) {
                                tb_port_info(&sw->ports[i], "disabled by eeprom\n");
                                continue;
                        }
                        ret = tb_init_port(&sw->ports[i]);
                        if (ret)
                                return ret;
                }
        }

        ret = device_add(&sw->dev);
        if (ret)
                return ret;

        ret = tb_switch_nvm_add(sw);
        if (ret) {
                device_del(&sw->dev);
                return ret;
        }

        pm_runtime_set_active(&sw->dev);
        if (sw->rpm) {
                pm_runtime_set_autosuspend_delay(&sw->dev, TB_AUTOSUSPEND_DELAY);
                pm_runtime_use_autosuspend(&sw->dev);
                pm_runtime_mark_last_busy(&sw->dev);
                pm_runtime_enable(&sw->dev);
                pm_request_autosuspend(&sw->dev);
        }

        return 0;
}

/**
 * tb_switch_remove() - Remove and release a switch
 * @sw: Switch to remove
 *
 * This will remove the switch from the domain and release it after last
 * reference count drops to zero. If there are switches connected below
 * this switch, they will be removed as well.
 */
void tb_switch_remove(struct tb_switch *sw)
{
        int i;

        if (sw->rpm) {
                pm_runtime_get_sync(&sw->dev);
                pm_runtime_disable(&sw->dev);
        }

        /* port 0 is the switch itself and never has a remote */
        for (i = 1; i <= sw->config.max_port_number; i++) {
                if (tb_is_upstream_port(&sw->ports[i]))
                        continue;
                if (sw->ports[i].remote)
                        tb_switch_remove(sw->ports[i].remote->sw);
                sw->ports[i].remote = NULL;
                if (sw->ports[i].xdomain)
                        tb_xdomain_remove(sw->ports[i].xdomain);
                sw->ports[i].xdomain = NULL;
        }

        if (!sw->is_unplugged)
                tb_plug_events_active(sw, false);

        tb_switch_nvm_remove(sw);
        device_unregister(&sw->dev);
}

/**
 * tb_sw_set_unplugged() - set is_unplugged on switch and downstream switches
 */
void tb_sw_set_unplugged(struct tb_switch *sw)
{
        int i;
        if (sw == sw->tb->root_switch) {
                tb_sw_WARN(sw, "cannot unplug root switch\n");
                return;
        }
        if (sw->is_unplugged) {
                tb_sw_WARN(sw, "is_unplugged already set\n");
                return;
        }
        sw->is_unplugged = true;
        for (i = 0; i <= sw->config.max_port_number; i++) {
                if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
                        tb_sw_set_unplugged(sw->ports[i].remote->sw);
        }
}

int tb_switch_resume(struct tb_switch *sw)
{
        int i, err;
        tb_sw_info(sw, "resuming switch\n");

        /*
         * Check for UID of the connected switches except for root
         * switch which we assume cannot be removed.
         */
        if (tb_route(sw)) {
                u64 uid;

                err = tb_drom_read_uid_only(sw, &uid);
                if (err) {
                        tb_sw_warn(sw, "uid read failed\n");
                        return err;
                }
                if (sw->uid != uid) {
                        tb_sw_info(sw,
                                "changed while suspended (uid %#llx -> %#llx)\n",
                                sw->uid, uid);
                        return -ENODEV;
                }
        }

        /* upload configuration */
        err = tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3);
        if (err)
                return err;

        err = tb_plug_events_active(sw, true);
        if (err)
                return err;

        /* check for surviving downstream switches */
        for (i = 1; i <= sw->config.max_port_number; i++) {
                struct tb_port *port = &sw->ports[i];
                if (tb_is_upstream_port(port))
                        continue;
                if (!port->remote)
                        continue;
                if (tb_wait_for_port(port, true) <= 0
                        || tb_switch_resume(port->remote->sw)) {
                        tb_port_warn(port,
                                     "lost during suspend, disconnecting\n");
                        tb_sw_set_unplugged(port->remote->sw);
                }
        }
        return 0;
}

void tb_switch_suspend(struct tb_switch *sw)
{
        int i, err;
        err = tb_plug_events_active(sw, false);
        if (err)
                return;

        for (i = 1; i <= sw->config.max_port_number; i++) {
                if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
                        tb_switch_suspend(sw->ports[i].remote->sw);
        }
        /*
         * TODO: invoke tb_cfg_prepare_to_sleep here? does not seem to have any
         * effect?
         */
}

struct tb_sw_lookup {
        struct tb *tb;
        u8 link;
        u8 depth;
        const uuid_t *uuid;
        u64 route;
};

static int tb_switch_match(struct device *dev, void *data)
{
        struct tb_switch *sw = tb_to_switch(dev);
        struct tb_sw_lookup *lookup = data;

        if (!sw)
                return 0;
        if (sw->tb != lookup->tb)
                return 0;

        if (lookup->uuid)
                return !memcmp(sw->uuid, lookup->uuid, sizeof(*lookup->uuid));

        if (lookup->route) {
                return sw->config.route_lo == lower_32_bits(lookup->route) &&
                       sw->config.route_hi == upper_32_bits(lookup->route);
        }

        /* Root switch is matched only by depth */
        if (!lookup->depth)
                return !sw->depth;

        return sw->link == lookup->link && sw->depth == lookup->depth;
}

/**
 * tb_switch_find_by_link_depth() - Find switch by link and depth
 * @tb: Domain the switch belongs
 * @link: Link number the switch is connected
 * @depth: Depth of the switch in link
 *
 * Returned switch has reference count increased so the caller needs to
 * call tb_switch_put() when done with the switch.
 */
struct tb_switch *tb_switch_find_by_link_depth(struct tb *tb, u8 link, u8 depth)
{
        struct tb_sw_lookup lookup;
        struct device *dev;

        memset(&lookup, 0, sizeof(lookup));
        lookup.tb = tb;
        lookup.link = link;
        lookup.depth = depth;

        dev = bus_find_device(&tb_bus_type, NULL, &lookup, tb_switch_match);
        if (dev)
                return tb_to_switch(dev);

        return NULL;
}

/**
 * tb_switch_find_by_uuid() - Find switch by UUID
 * @tb: Domain the switch belongs
 * @uuid: UUID to look for
 *
 * Returned switch has reference count increased so the caller needs to
 * call tb_switch_put() when done with the switch.
 */
struct tb_switch *tb_switch_find_by_uuid(struct tb *tb, const uuid_t *uuid)
{
        struct tb_sw_lookup lookup;
        struct device *dev;

        memset(&lookup, 0, sizeof(lookup));
        lookup.tb = tb;
        lookup.uuid = uuid;

        dev = bus_find_device(&tb_bus_type, NULL, &lookup, tb_switch_match);
        if (dev)
                return tb_to_switch(dev);

        return NULL;
}

/**
 * tb_switch_find_by_route() - Find switch by route string
 * @tb: Domain the switch belongs
 * @route: Route string to look for
 *
 * Returned switch has reference count increased so the caller needs to
 * call tb_switch_put() when done with the switch.
 */
struct tb_switch *tb_switch_find_by_route(struct tb *tb, u64 route)
{
        struct tb_sw_lookup lookup;
        struct device *dev;

        if (!route)
                return tb_switch_get(tb->root_switch);

        memset(&lookup, 0, sizeof(lookup));
        lookup.tb = tb;
        lookup.route = route;

        dev = bus_find_device(&tb_bus_type, NULL, &lookup, tb_switch_match);
        if (dev)
                return tb_to_switch(dev);

        return NULL;
}

void tb_switch_exit(void)
{
        ida_destroy(&nvm_ida);
}