// SPDX-License-Identifier: GPL-2.0
/*
 * Thunderbolt driver - control channel and configuration commands
 *
 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
 * Copyright (C) 2018, Intel Corporation
 */

#include <linux/crc32.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/dmapool.h>
#include <linux/workqueue.h>

#include "ctl.h"

#define CREATE_TRACE_POINTS
#include "trace.h"

#define TB_CTL_RX_PKG_COUNT     10
#define TB_CTL_RETRIES          4

/**
 * struct tb_ctl - Thunderbolt control channel
 * @nhi: Pointer to the NHI structure
 * @tx: Transmit ring
 * @rx: Receive ring
 * @frame_pool: DMA pool for control messages
 * @rx_packets: Received control messages
 * @request_queue_lock: Lock protecting @request_queue
 * @request_queue: List of outstanding requests
 * @running: Is the control channel running at the moment
 * @timeout_msec: Default timeout for non-raw control messages
 * @callback: Callback called when hotplug message is received
 * @callback_data: Data passed to @callback
 * @index: Domain number. This will be output with the trace record.
 */
struct tb_ctl {
        struct tb_nhi *nhi;
        struct tb_ring *tx;
        struct tb_ring *rx;

        struct dma_pool *frame_pool;
        struct ctl_pkg *rx_packets[TB_CTL_RX_PKG_COUNT];
        struct mutex request_queue_lock;
        struct list_head request_queue;
        bool running;

        int timeout_msec;
        event_cb callback;
        void *callback_data;

        int index;
};


#define tb_ctl_WARN(ctl, format, arg...) \
        dev_WARN(&(ctl)->nhi->pdev->dev, format, ## arg)

#define tb_ctl_err(ctl, format, arg...) \
        dev_err(&(ctl)->nhi->pdev->dev, format, ## arg)

#define tb_ctl_warn(ctl, format, arg...) \
        dev_warn(&(ctl)->nhi->pdev->dev, format, ## arg)

#define tb_ctl_info(ctl, format, arg...) \
        dev_info(&(ctl)->nhi->pdev->dev, format, ## arg)

#define tb_ctl_dbg(ctl, format, arg...) \
        dev_dbg(&(ctl)->nhi->pdev->dev, format, ## arg)

#define tb_ctl_dbg_once(ctl, format, arg...) \
        dev_dbg_once(&(ctl)->nhi->pdev->dev, format, ## arg)

static DECLARE_WAIT_QUEUE_HEAD(tb_cfg_request_cancel_queue);
/* Serializes access to request kref_get/put */
static DEFINE_MUTEX(tb_cfg_request_lock);

/**
 * tb_cfg_request_alloc() - Allocates a new config request
 *
 * This is refcounted object so when you are done with this, call
 * tb_cfg_request_put() to it.
 *
 * Return: &struct tb_cfg_request on success, %NULL otherwise.
 */
struct tb_cfg_request *tb_cfg_request_alloc(void)
{
        struct tb_cfg_request *req;

        req = kzalloc_obj(*req);
        if (!req)
                return NULL;

        kref_init(&req->kref);

        return req;
}

/**
 * tb_cfg_request_get() - Increase refcount of a request
 * @req: Request whose refcount is increased
 */
void tb_cfg_request_get(struct tb_cfg_request *req)
{
        mutex_lock(&tb_cfg_request_lock);
        kref_get(&req->kref);
        mutex_unlock(&tb_cfg_request_lock);
}

static void tb_cfg_request_destroy(struct kref *kref)
{
        struct tb_cfg_request *req = container_of(kref, typeof(*req), kref);

        kfree(req);
}

/**
 * tb_cfg_request_put() - Decrease refcount and possibly release the request
 * @req: Request whose refcount is decreased
 *
 * Call this function when you are done with the request. When refcount
 * goes to %0 the object is released.
 */
void tb_cfg_request_put(struct tb_cfg_request *req)
{
        mutex_lock(&tb_cfg_request_lock);
        kref_put(&req->kref, tb_cfg_request_destroy);
        mutex_unlock(&tb_cfg_request_lock);
}

static int tb_cfg_request_enqueue(struct tb_ctl *ctl,
                                  struct tb_cfg_request *req)
{
        WARN_ON(test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags));
        WARN_ON(req->ctl);

        mutex_lock(&ctl->request_queue_lock);
        if (!ctl->running) {
                mutex_unlock(&ctl->request_queue_lock);
                return -ENOTCONN;
        }
        req->ctl = ctl;
        list_add_tail(&req->list, &ctl->request_queue);
        set_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
        mutex_unlock(&ctl->request_queue_lock);
        return 0;
}

static void tb_cfg_request_dequeue(struct tb_cfg_request *req)
{
        struct tb_ctl *ctl = req->ctl;

        mutex_lock(&ctl->request_queue_lock);
        if (!test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags)) {
                mutex_unlock(&ctl->request_queue_lock);
                return;
        }

        list_del(&req->list);
        clear_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
        if (test_bit(TB_CFG_REQUEST_CANCELED, &req->flags))
                wake_up(&tb_cfg_request_cancel_queue);
        mutex_unlock(&ctl->request_queue_lock);
}

static bool tb_cfg_request_is_active(struct tb_cfg_request *req)
{
        return test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
}

static struct tb_cfg_request *
tb_cfg_request_find(struct tb_ctl *ctl, struct ctl_pkg *pkg)
{
        struct tb_cfg_request *req = NULL, *iter;

        mutex_lock(&pkg->ctl->request_queue_lock);
        list_for_each_entry(iter, &pkg->ctl->request_queue, list) {
                tb_cfg_request_get(iter);
                if (iter->match(iter, pkg)) {
                        req = iter;
                        break;
                }
                tb_cfg_request_put(iter);
        }
        mutex_unlock(&pkg->ctl->request_queue_lock);

        return req;
}

/* utility functions */


static int check_header(const struct ctl_pkg *pkg, u32 len,
                        enum tb_cfg_pkg_type type, u64 route)
{
        struct tb_cfg_header *header = pkg->buffer;

        /* check frame, TODO: frame flags */
        if (WARN(len != pkg->frame.size,
                        "wrong framesize (expected %#x, got %#x)\n",
                        len, pkg->frame.size))
                return -EIO;
        if (WARN(type != pkg->frame.eof, "wrong eof (expected %#x, got %#x)\n",
                        type, pkg->frame.eof))
                return -EIO;
        if (WARN(pkg->frame.sof, "wrong sof (expected 0x0, got %#x)\n",
                        pkg->frame.sof))
                return -EIO;

        /* check header */
        if (WARN(header->unknown != 1 << 9,
                        "header->unknown is %#x\n", header->unknown))
                return -EIO;
        if (WARN(route != tb_cfg_get_route(header),
                        "wrong route (expected %llx, got %llx)",
                        route, tb_cfg_get_route(header)))
                return -EIO;
        return 0;
}

static int check_config_address(struct tb_cfg_address addr,
                                enum tb_cfg_space space, u32 offset,
                                u32 length)
{
        if (WARN(addr.zero, "addr.zero is %#x\n", addr.zero))
                return -EIO;
        if (WARN(space != addr.space, "wrong space (expected %x, got %x\n)",
                        space, addr.space))
                return -EIO;
        if (WARN(offset != addr.offset, "wrong offset (expected %x, got %x\n)",
                        offset, addr.offset))
                return -EIO;
        if (WARN(length != addr.length, "wrong space (expected %x, got %x\n)",
                        length, addr.length))
                return -EIO;
        /*
         * We cannot check addr->port as it is set to the upstream port of the
         * sender.
         */
        return 0;
}

static struct tb_cfg_result decode_error(const struct ctl_pkg *response)
{
        struct cfg_error_pkg *pkg = response->buffer;
        struct tb_cfg_result res = { 0 };
        res.response_route = tb_cfg_get_route(&pkg->header);
        res.response_port = 0;
        res.err = check_header(response, sizeof(*pkg), TB_CFG_PKG_ERROR,
                               tb_cfg_get_route(&pkg->header));
        if (res.err)
                return res;

        res.err = 1;
        res.tb_error = pkg->error;
        res.response_port = pkg->port;
        return res;

}

static struct tb_cfg_result parse_header(const struct ctl_pkg *pkg, u32 len,
                                         enum tb_cfg_pkg_type type, u64 route)
{
        struct tb_cfg_header *header = pkg->buffer;
        struct tb_cfg_result res = { 0 };

        if (pkg->frame.eof == TB_CFG_PKG_ERROR)
                return decode_error(pkg);

        res.response_port = 0; /* will be updated later for cfg_read/write */
        res.response_route = tb_cfg_get_route(header);
        res.err = check_header(pkg, len, type, route);
        return res;
}

static void tb_cfg_print_error(struct tb_ctl *ctl, enum tb_cfg_space space,
                               const struct tb_cfg_result *res)
{
        WARN_ON(res->err != 1);
        switch (res->tb_error) {
        case TB_CFG_ERROR_PORT_NOT_CONNECTED:
                /* Port is not connected. This can happen during surprise
                 * removal. Do not warn. */
                return;
        case TB_CFG_ERROR_INVALID_CONFIG_SPACE:
                /*
                 * Invalid cfg_space/offset/length combination in
                 * cfg_read/cfg_write.
                 */
                tb_ctl_dbg_once(ctl, "%llx:%x: invalid config space (%u) or offset\n",
                                res->response_route, res->response_port, space);
                return;
        case TB_CFG_ERROR_NO_SUCH_PORT:
                /*
                 * - The route contains a non-existent port.
                 * - The route contains a non-PHY port (e.g. PCIe).
                 * - The port in cfg_read/cfg_write does not exist.
                 */
                tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Invalid port\n",
                        res->response_route, res->response_port);
                return;
        case TB_CFG_ERROR_LOOP:
                tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Route contains a loop\n",
                        res->response_route, res->response_port);
                return;
        case TB_CFG_ERROR_LOCK:
                tb_ctl_warn(ctl, "%llx:%x: downstream port is locked\n",
                            res->response_route, res->response_port);
                return;
        default:
                /* 5,6,7,9 and 11 are also valid error codes */
                tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Unknown error\n",
                        res->response_route, res->response_port);
                return;
        }
}

static __be32 tb_crc(const void *data, size_t len)
{
        return cpu_to_be32(~crc32c(~0, data, len));
}

static void tb_ctl_pkg_free(struct ctl_pkg *pkg)
{
        if (pkg) {
                dma_pool_free(pkg->ctl->frame_pool,
                              pkg->buffer, pkg->frame.buffer_phy);
                kfree(pkg);
        }
}

static struct ctl_pkg *tb_ctl_pkg_alloc(struct tb_ctl *ctl)
{
        struct ctl_pkg *pkg = kzalloc_obj(*pkg);
        if (!pkg)
                return NULL;
        pkg->ctl = ctl;
        pkg->buffer = dma_pool_alloc(ctl->frame_pool, GFP_KERNEL,
                                     &pkg->frame.buffer_phy);
        if (!pkg->buffer) {
                kfree(pkg);
                return NULL;
        }
        return pkg;
}


/* RX/TX handling */

static void tb_ctl_tx_callback(struct tb_ring *ring, struct ring_frame *frame,
                               bool canceled)
{
        struct ctl_pkg *pkg = container_of(frame, typeof(*pkg), frame);
        tb_ctl_pkg_free(pkg);
}

/*
 * tb_cfg_tx() - transmit a packet on the control channel
 *
 * len must be a multiple of four.
 *
 * Return: %0 on success, negative errno otherwise.
 */
static int tb_ctl_tx(struct tb_ctl *ctl, const void *data, size_t len,
                     enum tb_cfg_pkg_type type)
{
        int res;
        struct ctl_pkg *pkg;
        if (len % 4 != 0) { /* required for le->be conversion */
                tb_ctl_WARN(ctl, "TX: invalid size: %zu\n", len);
                return -EINVAL;
        }
        if (len > TB_FRAME_SIZE - 4) { /* checksum is 4 bytes */
                tb_ctl_WARN(ctl, "TX: packet too large: %zu/%d\n",
                            len, TB_FRAME_SIZE - 4);
                return -EINVAL;
        }
        pkg = tb_ctl_pkg_alloc(ctl);
        if (!pkg)
                return -ENOMEM;
        pkg->frame.callback = tb_ctl_tx_callback;
        pkg->frame.size = len + 4;
        pkg->frame.sof = type;
        pkg->frame.eof = type;

        trace_tb_tx(ctl->index, type, data, len);

        cpu_to_be32_array(pkg->buffer, data, len / 4);
        *(__be32 *) (pkg->buffer + len) = tb_crc(pkg->buffer, len);

        res = tb_ring_tx(ctl->tx, &pkg->frame);
        if (res) /* ring is stopped */
                tb_ctl_pkg_free(pkg);
        return res;
}

/*
 * tb_ctl_handle_event() - acknowledge a plug event, invoke ctl->callback
 */
static bool tb_ctl_handle_event(struct tb_ctl *ctl, enum tb_cfg_pkg_type type,
                                struct ctl_pkg *pkg, size_t size)
{
        trace_tb_event(ctl->index, type, pkg->buffer, size);
        return ctl->callback(ctl->callback_data, type, pkg->buffer, size);
}

static void tb_ctl_rx_submit(struct ctl_pkg *pkg)
{
        tb_ring_rx(pkg->ctl->rx, &pkg->frame); /*
                                             * We ignore failures during stop.
                                             * All rx packets are referenced
                                             * from ctl->rx_packets, so we do
                                             * not lose them.
                                             */
}

static int tb_async_error(const struct ctl_pkg *pkg)
{
        const struct cfg_error_pkg *error = pkg->buffer;

        if (pkg->frame.eof != TB_CFG_PKG_ERROR)
                return false;

        switch (error->error) {
        case TB_CFG_ERROR_LINK_ERROR:
        case TB_CFG_ERROR_HEC_ERROR_DETECTED:
        case TB_CFG_ERROR_FLOW_CONTROL_ERROR:
        case TB_CFG_ERROR_DP_BW:
        case TB_CFG_ERROR_ROP_CMPLT:
        case TB_CFG_ERROR_POP_CMPLT:
        case TB_CFG_ERROR_PCIE_WAKE:
        case TB_CFG_ERROR_DP_CON_CHANGE:
        case TB_CFG_ERROR_DPTX_DISCOVERY:
        case TB_CFG_ERROR_LINK_RECOVERY:
        case TB_CFG_ERROR_ASYM_LINK:
                return true;

        default:
                return false;
        }
}

static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
                               bool canceled)
{
        struct ctl_pkg *pkg = container_of(frame, typeof(*pkg), frame);
        struct tb_cfg_request *req;
        __be32 crc32;

        if (canceled)
                return; /*
                         * ring is stopped, packet is referenced from
                         * ctl->rx_packets.
                         */

        if (frame->size < 4 || frame->size % 4 != 0) {
                tb_ctl_err(pkg->ctl, "RX: invalid size %#x, dropping packet\n",
                           frame->size);
                goto rx;
        }

        frame->size -= 4; /* remove checksum */
        crc32 = tb_crc(pkg->buffer, frame->size);
        be32_to_cpu_array(pkg->buffer, pkg->buffer, frame->size / 4);

        switch (frame->eof) {
        case TB_CFG_PKG_READ:
        case TB_CFG_PKG_WRITE:
        case TB_CFG_PKG_ERROR:
        case TB_CFG_PKG_OVERRIDE:
        case TB_CFG_PKG_RESET:
                if (*(__be32 *)(pkg->buffer + frame->size) != crc32) {
                        tb_ctl_err(pkg->ctl,
                                   "RX: checksum mismatch, dropping packet\n");
                        goto rx;
                }
                if (tb_async_error(pkg)) {
                        tb_ctl_handle_event(pkg->ctl, frame->eof,
                                            pkg, frame->size);
                        goto rx;
                }
                break;

        case TB_CFG_PKG_EVENT:
        case TB_CFG_PKG_XDOMAIN_RESP:
        case TB_CFG_PKG_XDOMAIN_REQ:
                if (*(__be32 *)(pkg->buffer + frame->size) != crc32) {
                        tb_ctl_err(pkg->ctl,
                                   "RX: checksum mismatch, dropping packet\n");
                        goto rx;
                }
                fallthrough;
        case TB_CFG_PKG_ICM_EVENT:
                if (tb_ctl_handle_event(pkg->ctl, frame->eof, pkg, frame->size))
                        goto rx;
                break;

        default:
                break;
        }

        /*
         * The received packet will be processed only if there is an
         * active request and that the packet is what is expected. This
         * prevents packets such as replies coming after timeout has
         * triggered from messing with the active requests.
         */
        req = tb_cfg_request_find(pkg->ctl, pkg);

        trace_tb_rx(pkg->ctl->index, frame->eof, pkg->buffer, frame->size, !req);

        if (req) {
                if (req->copy(req, pkg))
                        schedule_work(&req->work);
                tb_cfg_request_put(req);
        }

rx:
        tb_ctl_rx_submit(pkg);
}

static void tb_cfg_request_work(struct work_struct *work)
{
        struct tb_cfg_request *req = container_of(work, typeof(*req), work);

        if (!test_bit(TB_CFG_REQUEST_CANCELED, &req->flags))
                req->callback(req->callback_data);

        tb_cfg_request_dequeue(req);
        tb_cfg_request_put(req);
}

/**
 * tb_cfg_request() - Start control request not waiting for it to complete
 * @ctl: Control channel to use
 * @req: Request to start
 * @callback: Callback called when the request is completed
 * @callback_data: Data to be passed to @callback
 *
 * This queues @req on the given control channel without waiting for it
 * to complete. When the request completes @callback is called.
 *
 * Return: %0 on success, negative errno otherwise.
 */
int tb_cfg_request(struct tb_ctl *ctl, struct tb_cfg_request *req,
                   void (*callback)(void *), void *callback_data)
{
        int ret;

        req->flags = 0;
        req->callback = callback;
        req->callback_data = callback_data;
        INIT_WORK(&req->work, tb_cfg_request_work);
        INIT_LIST_HEAD(&req->list);

        tb_cfg_request_get(req);
        ret = tb_cfg_request_enqueue(ctl, req);
        if (ret)
                goto err_put;

        ret = tb_ctl_tx(ctl, req->request, req->request_size,
                        req->request_type);
        if (ret)
                goto err_dequeue;

        if (!req->response)
                schedule_work(&req->work);

        return 0;

err_dequeue:
        tb_cfg_request_dequeue(req);
err_put:
        tb_cfg_request_put(req);

        return ret;
}

/**
 * tb_cfg_request_cancel() - Cancel a control request
 * @req: Request to cancel
 * @err: Error to assign to the request
 *
 * This function can be used to cancel ongoing request. It will wait
 * until the request is not active anymore.
 */
void tb_cfg_request_cancel(struct tb_cfg_request *req, int err)
{
        set_bit(TB_CFG_REQUEST_CANCELED, &req->flags);
        schedule_work(&req->work);
        wait_event(tb_cfg_request_cancel_queue, !tb_cfg_request_is_active(req));
        req->result.err = err;
}

static void tb_cfg_request_complete(void *data)
{
        complete(data);
}

/**
 * tb_cfg_request_sync() - Start control request and wait until it completes
 * @ctl: Control channel to use
 * @req: Request to start
 * @timeout_msec: Timeout how long to wait @req to complete
 *
 * Starts a control request and waits until it completes. If timeout
 * triggers the request is canceled before function returns. Note the
 * caller needs to make sure only one message for given switch is active
 * at a time.
 *
 * Return: &struct tb_cfg_result with non-zero @err field if error
 * has occurred.
 */
struct tb_cfg_result tb_cfg_request_sync(struct tb_ctl *ctl,
                                         struct tb_cfg_request *req,
                                         int timeout_msec)
{
        unsigned long timeout = msecs_to_jiffies(timeout_msec);
        struct tb_cfg_result res = { 0 };
        DECLARE_COMPLETION_ONSTACK(done);
        int ret;

        ret = tb_cfg_request(ctl, req, tb_cfg_request_complete, &done);
        if (ret) {
                res.err = ret;
                return res;
        }

        if (!wait_for_completion_timeout(&done, timeout))
                tb_cfg_request_cancel(req, -ETIMEDOUT);

        flush_work(&req->work);

        return req->result;
}

/* public interface, alloc/start/stop/free */

/**
 * tb_ctl_alloc() - allocate a control channel
 * @nhi: Pointer to NHI
 * @index: Domain number
 * @timeout_msec: Default timeout used with non-raw control messages
 * @cb: Callback called for plug events
 * @cb_data: Data passed to @cb
 *
 * cb will be invoked once for every hot plug event.
 *
 * Return: Pointer to &struct tb_ctl, %NULL on failure.
 */
struct tb_ctl *tb_ctl_alloc(struct tb_nhi *nhi, int index, int timeout_msec,
                            event_cb cb, void *cb_data)
{
        int i;
        struct tb_ctl *ctl = kzalloc_obj(*ctl);
        if (!ctl)
                return NULL;

        ctl->nhi = nhi;
        ctl->index = index;
        ctl->timeout_msec = timeout_msec;
        ctl->callback = cb;
        ctl->callback_data = cb_data;

        mutex_init(&ctl->request_queue_lock);
        INIT_LIST_HEAD(&ctl->request_queue);
        ctl->frame_pool = dma_pool_create("thunderbolt_ctl", &nhi->pdev->dev,
                                         TB_FRAME_SIZE, 4, 0);
        if (!ctl->frame_pool)
                goto err;

        ctl->tx = tb_ring_alloc_tx(nhi, 0, 10, RING_FLAG_NO_SUSPEND);
        if (!ctl->tx)
                goto err;

        ctl->rx = tb_ring_alloc_rx(nhi, 0, 10, RING_FLAG_NO_SUSPEND, 0, 0xffff,
                                   0xffff, NULL, NULL);
        if (!ctl->rx)
                goto err;

        for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++) {
                ctl->rx_packets[i] = tb_ctl_pkg_alloc(ctl);
                if (!ctl->rx_packets[i])
                        goto err;
                ctl->rx_packets[i]->frame.callback = tb_ctl_rx_callback;
        }

        tb_ctl_dbg(ctl, "control channel created\n");
        return ctl;
err:
        tb_ctl_free(ctl);
        return NULL;
}

/**
 * tb_ctl_free() - free a control channel
 * @ctl: Control channel to free
 *
 * Must be called after tb_ctl_stop.
 *
 * Must NOT be called from ctl->callback.
 */
void tb_ctl_free(struct tb_ctl *ctl)
{
        int i;

        if (!ctl)
                return;

        if (ctl->rx)
                tb_ring_free(ctl->rx);
        if (ctl->tx)
                tb_ring_free(ctl->tx);

        /* free RX packets */
        for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++)
                tb_ctl_pkg_free(ctl->rx_packets[i]);


        dma_pool_destroy(ctl->frame_pool);
        kfree(ctl);
}

/**
 * tb_ctl_start() - start/resume the control channel
 * @ctl: Control channel to start
 */
void tb_ctl_start(struct tb_ctl *ctl)
{
        int i;
        tb_ctl_dbg(ctl, "control channel starting...\n");
        tb_ring_start(ctl->tx); /* is used to ack hotplug packets, start first */
        tb_ring_start(ctl->rx);
        for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++)
                tb_ctl_rx_submit(ctl->rx_packets[i]);

        ctl->running = true;
}

/**
 * tb_ctl_stop() - pause the control channel
 * @ctl: Control channel to stop
 *
 * All invocations of ctl->callback will have finished after this method
 * returns.
 *
 * Must NOT be called from ctl->callback.
 */
void tb_ctl_stop(struct tb_ctl *ctl)
{
        mutex_lock(&ctl->request_queue_lock);
        ctl->running = false;
        mutex_unlock(&ctl->request_queue_lock);

        tb_ring_stop(ctl->rx);
        tb_ring_stop(ctl->tx);

        if (!list_empty(&ctl->request_queue))
                tb_ctl_WARN(ctl, "dangling request in request_queue\n");
        INIT_LIST_HEAD(&ctl->request_queue);
        tb_ctl_dbg(ctl, "control channel stopped\n");
}

/* public interface, commands */

/**
 * tb_cfg_ack_notification() - Ack notification
 * @ctl: Control channel to use
 * @route: Router that originated the event
 * @error: Pointer to the notification package
 *
 * Call this as a response for non-plug notification to ack it.
 *
 * Return: %0 on success, negative errno otherwise.
 */
int tb_cfg_ack_notification(struct tb_ctl *ctl, u64 route,
                            const struct cfg_error_pkg *error)
{
        struct cfg_ack_pkg pkg = {
                .header = tb_cfg_make_header(route),
        };
        const char *name;

        switch (error->error) {
        case TB_CFG_ERROR_LINK_ERROR:
                name = "link error";
                break;
        case TB_CFG_ERROR_HEC_ERROR_DETECTED:
                name = "HEC error";
                break;
        case TB_CFG_ERROR_FLOW_CONTROL_ERROR:
                name = "flow control error";
                break;
        case TB_CFG_ERROR_DP_BW:
                name = "DP_BW";
                break;
        case TB_CFG_ERROR_ROP_CMPLT:
                name = "router operation completion";
                break;
        case TB_CFG_ERROR_POP_CMPLT:
                name = "port operation completion";
                break;
        case TB_CFG_ERROR_PCIE_WAKE:
                name = "PCIe wake";
                break;
        case TB_CFG_ERROR_DP_CON_CHANGE:
                name = "DP connector change";
                break;
        case TB_CFG_ERROR_DPTX_DISCOVERY:
                name = "DPTX discovery";
                break;
        case TB_CFG_ERROR_LINK_RECOVERY:
                name = "link recovery";
                break;
        case TB_CFG_ERROR_ASYM_LINK:
                name = "asymmetric link";
                break;
        default:
                name = "unknown";
                break;
        }

        tb_ctl_dbg(ctl, "acking %s (%#x) notification on %llx\n", name,
                   error->error, route);

        return tb_ctl_tx(ctl, &pkg, sizeof(pkg), TB_CFG_PKG_NOTIFY_ACK);
}

/**
 * tb_cfg_ack_plug() - Ack hot plug/unplug event
 * @ctl: Control channel to use
 * @route: Router that originated the event
 * @port: Port where the hot plug/unplug happened
 * @unplug: Ack hot plug or unplug
 *
 * Call this as a response for hot plug/unplug event to ack it.
 *
 * Return: %0 on success, negative errno otherwise.
 */
int tb_cfg_ack_plug(struct tb_ctl *ctl, u64 route, u32 port, bool unplug)
{
        struct cfg_error_pkg pkg = {
                .header = tb_cfg_make_header(route),
                .port = port,
                .error = TB_CFG_ERROR_ACK_PLUG_EVENT,
                .pg = unplug ? TB_CFG_ERROR_PG_HOT_UNPLUG
                             : TB_CFG_ERROR_PG_HOT_PLUG,
        };
        tb_ctl_dbg(ctl, "acking hot %splug event on %llx:%u\n",
                   unplug ? "un" : "", route, port);
        return tb_ctl_tx(ctl, &pkg, sizeof(pkg), TB_CFG_PKG_ERROR);
}

static bool tb_cfg_match(const struct tb_cfg_request *req,
                         const struct ctl_pkg *pkg)
{
        u64 route = tb_cfg_get_route(pkg->buffer) & ~BIT_ULL(63);

        if (pkg->frame.eof == TB_CFG_PKG_ERROR)
                return true;

        if (pkg->frame.eof != req->response_type)
                return false;
        if (route != tb_cfg_get_route(req->request))
                return false;
        if (pkg->frame.size != req->response_size)
                return false;

        if (pkg->frame.eof == TB_CFG_PKG_READ ||
            pkg->frame.eof == TB_CFG_PKG_WRITE) {
                const struct cfg_read_pkg *req_hdr = req->request;
                const struct cfg_read_pkg *res_hdr = pkg->buffer;

                if (req_hdr->addr.seq != res_hdr->addr.seq)
                        return false;
        }

        return true;
}

static bool tb_cfg_copy(struct tb_cfg_request *req, const struct ctl_pkg *pkg)
{
        struct tb_cfg_result res;

        /* Now make sure it is in expected format */
        res = parse_header(pkg, req->response_size, req->response_type,
                           tb_cfg_get_route(req->request));
        if (!res.err)
                memcpy(req->response, pkg->buffer, req->response_size);

        req->result = res;

        /* Always complete when first response is received */
        return true;
}

/**
 * tb_cfg_reset() - send a reset packet and wait for a response
 * @ctl: Control channel pointer
 * @route: Router string for the router to send reset
 *
 * If the switch at route is incorrectly configured then we will not receive a
 * reply (even though the switch will reset). The caller should check for
 * -ETIMEDOUT and attempt to reconfigure the switch.
 *
 * Return: &struct tb_cfg_result with non-zero @err field if error
 * has occurred.
 */
struct tb_cfg_result tb_cfg_reset(struct tb_ctl *ctl, u64 route)
{
        struct cfg_reset_pkg request = { .header = tb_cfg_make_header(route) };
        struct tb_cfg_result res = { 0 };
        struct tb_cfg_header reply;
        struct tb_cfg_request *req;

        req = tb_cfg_request_alloc();
        if (!req) {
                res.err = -ENOMEM;
                return res;
        }

        req->match = tb_cfg_match;
        req->copy = tb_cfg_copy;
        req->request = &request;
        req->request_size = sizeof(request);
        req->request_type = TB_CFG_PKG_RESET;
        req->response = &reply;
        req->response_size = sizeof(reply);
        req->response_type = TB_CFG_PKG_RESET;

        res = tb_cfg_request_sync(ctl, req, ctl->timeout_msec);

        tb_cfg_request_put(req);

        return res;
}

/**
 * tb_cfg_read_raw() - read from config space into buffer
 * @ctl: Pointer to the control channel
 * @buffer: Buffer where the data is read
 * @route: Route string of the router
 * @port: Port number when reading from %TB_CFG_PORT, %0 otherwise
 * @space: Config space selector
 * @offset: Dword word offset of the register to start reading
 * @length: Number of dwords to read
 * @timeout_msec: Timeout in ms how long to wait for the response
 *
 * Reads from router config space without translating the possible error.
 *
 * Return: &struct tb_cfg_result with non-zero @err field if error
 * has occurred.
 */
struct tb_cfg_result tb_cfg_read_raw(struct tb_ctl *ctl, void *buffer,
                u64 route, u32 port, enum tb_cfg_space space,
                u32 offset, u32 length, int timeout_msec)
{
        struct tb_cfg_result res = { 0 };
        struct cfg_read_pkg request = {
                .header = tb_cfg_make_header(route),
                .addr = {
                        .port = port,
                        .space = space,
                        .offset = offset,
                        .length = length,
                },
        };
        struct cfg_write_pkg reply;
        int retries = 0;

        while (retries < TB_CTL_RETRIES) {
                struct tb_cfg_request *req;

                req = tb_cfg_request_alloc();
                if (!req) {
                        res.err = -ENOMEM;
                        return res;
                }

                request.addr.seq = retries++;

                req->match = tb_cfg_match;
                req->copy = tb_cfg_copy;
                req->request = &request;
                req->request_size = sizeof(request);
                req->request_type = TB_CFG_PKG_READ;
                req->response = &reply;
                req->response_size = 12 + 4 * length;
                req->response_type = TB_CFG_PKG_READ;

                res = tb_cfg_request_sync(ctl, req, timeout_msec);

                tb_cfg_request_put(req);

                if (res.err != -ETIMEDOUT)
                        break;

                /* Wait a bit (arbitrary time) until we send a retry */
                usleep_range(10, 100);
        }

        if (res.err)
                return res;

        res.response_port = reply.addr.port;
        res.err = check_config_address(reply.addr, space, offset, length);
        if (!res.err)
                memcpy(buffer, &reply.data, 4 * length);
        return res;
}

/**
 * tb_cfg_write_raw() - write from buffer into config space
 * @ctl: Pointer to the control channel
 * @buffer: Data to write
 * @route: Route string of the router
 * @port: Port number when writing to %TB_CFG_PORT, %0 otherwise
 * @space: Config space selector
 * @offset: Dword word offset of the register to start writing
 * @length: Number of dwords to write
 * @timeout_msec: Timeout in ms how long to wait for the response
 *
 * Writes to router config space without translating the possible error.
 *
 * Return: &struct tb_cfg_result with non-zero @err field if error
 * has occurred.
 */
struct tb_cfg_result tb_cfg_write_raw(struct tb_ctl *ctl, const void *buffer,
                u64 route, u32 port, enum tb_cfg_space space,
                u32 offset, u32 length, int timeout_msec)
{
        struct tb_cfg_result res = { 0 };
        struct cfg_write_pkg request = {
                .header = tb_cfg_make_header(route),
                .addr = {
                        .port = port,
                        .space = space,
                        .offset = offset,
                        .length = length,
                },
        };
        struct cfg_read_pkg reply;
        int retries = 0;

        memcpy(&request.data, buffer, length * 4);

        while (retries < TB_CTL_RETRIES) {
                struct tb_cfg_request *req;

                req = tb_cfg_request_alloc();
                if (!req) {
                        res.err = -ENOMEM;
                        return res;
                }

                request.addr.seq = retries++;

                req->match = tb_cfg_match;
                req->copy = tb_cfg_copy;
                req->request = &request;
                req->request_size = 12 + 4 * length;
                req->request_type = TB_CFG_PKG_WRITE;
                req->response = &reply;
                req->response_size = sizeof(reply);
                req->response_type = TB_CFG_PKG_WRITE;

                res = tb_cfg_request_sync(ctl, req, timeout_msec);

                tb_cfg_request_put(req);

                if (res.err != -ETIMEDOUT)
                        break;

                /* Wait a bit (arbitrary time) until we send a retry */
                usleep_range(10, 100);
        }

        if (res.err)
                return res;

        res.response_port = reply.addr.port;
        res.err = check_config_address(reply.addr, space, offset, length);
        return res;
}

static int tb_cfg_get_error(struct tb_ctl *ctl, enum tb_cfg_space space,
                            const struct tb_cfg_result *res)
{
        /*
         * For unimplemented ports access to port config space may return
         * TB_CFG_ERROR_INVALID_CONFIG_SPACE (alternatively their type is
         * set to TB_TYPE_INACTIVE). In the former case return -ENODEV so
         * that the caller can mark the port as disabled.
         */
        if (space == TB_CFG_PORT &&
            res->tb_error == TB_CFG_ERROR_INVALID_CONFIG_SPACE)
                return -ENODEV;

        tb_cfg_print_error(ctl, space, res);

        if (res->tb_error == TB_CFG_ERROR_LOCK)
                return -EACCES;
        if (res->tb_error == TB_CFG_ERROR_PORT_NOT_CONNECTED)
                return -ENOTCONN;

        return -EIO;
}

int tb_cfg_read(struct tb_ctl *ctl, void *buffer, u64 route, u32 port,
                enum tb_cfg_space space, u32 offset, u32 length)
{
        struct tb_cfg_result res = tb_cfg_read_raw(ctl, buffer, route, port,
                        space, offset, length, ctl->timeout_msec);
        switch (res.err) {
        case 0:
                /* Success */
                break;

        case 1:
                /* Thunderbolt error, tb_error holds the actual number */
                return tb_cfg_get_error(ctl, space, &res);

        case -ETIMEDOUT:
                tb_ctl_warn(ctl, "%llx: timeout reading config space %u from %#x\n",
                            route, space, offset);
                break;

        default:
                WARN(1, "tb_cfg_read: %d\n", res.err);
                break;
        }
        return res.err;
}

int tb_cfg_write(struct tb_ctl *ctl, const void *buffer, u64 route, u32 port,
                 enum tb_cfg_space space, u32 offset, u32 length)
{
        struct tb_cfg_result res = tb_cfg_write_raw(ctl, buffer, route, port,
                        space, offset, length, ctl->timeout_msec);
        switch (res.err) {
        case 0:
                /* Success */
                break;

        case 1:
                /* Thunderbolt error, tb_error holds the actual number */
                return tb_cfg_get_error(ctl, space, &res);

        case -ETIMEDOUT:
                tb_ctl_warn(ctl, "%llx: timeout writing config space %u to %#x\n",
                            route, space, offset);
                break;

        default:
                WARN(1, "tb_cfg_write: %d\n", res.err);
                break;
        }
        return res.err;
}

/**
 * tb_cfg_get_upstream_port() - get upstream port number of switch at route
 * @ctl: Pointer to the control channel
 * @route: Route string of the router
 *
 * Reads the first dword from the switches TB_CFG_SWITCH config area and
 * returns the port number from which the reply originated.
 *
 * Return: Upstream port number on success or negative error code on failure.
 */
int tb_cfg_get_upstream_port(struct tb_ctl *ctl, u64 route)
{
        u32 dummy;
        struct tb_cfg_result res = tb_cfg_read_raw(ctl, &dummy, route, 0,
                                                   TB_CFG_SWITCH, 0, 1,
                                                   ctl->timeout_msec);
        if (res.err == 1)
                return -EIO;
        if (res.err)
                return res.err;
        return res.response_port;
}