xref: /qemu/hw/usb/core.c (revision 9a77a0f5)

/*
 * QEMU USB emulation
 *
 * Copyright (c) 2005 Fabrice Bellard
 *
 * 2008 Generic packet handler rewrite by Max Krasnyansky
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "qemu-common.h"
#include "hw/usb.h"
#include "iov.h"
#include "trace.h"

void usb_attach(USBPort *port)
{
    USBDevice *dev = port->dev;

    assert(dev != NULL);
    assert(dev->attached);
    assert(dev->state == USB_STATE_NOTATTACHED);
    port->ops->attach(port);
    dev->state = USB_STATE_ATTACHED;
    usb_device_handle_attach(dev);
}

void usb_detach(USBPort *port)
{
    USBDevice *dev = port->dev;

    assert(dev != NULL);
    assert(dev->state != USB_STATE_NOTATTACHED);
    port->ops->detach(port);
    dev->state = USB_STATE_NOTATTACHED;
}

void usb_port_reset(USBPort *port)
{
    USBDevice *dev = port->dev;

    assert(dev != NULL);
    usb_detach(port);
    usb_attach(port);
    usb_device_reset(dev);
}

void usb_device_reset(USBDevice *dev)
{
    if (dev == NULL || !dev->attached) {
        return;
    }
    dev->remote_wakeup = 0;
    dev->addr = 0;
    dev->state = USB_STATE_DEFAULT;
    usb_device_handle_reset(dev);
}

void usb_wakeup(USBEndpoint *ep)
{
    USBDevice *dev = ep->dev;
    USBBus *bus = usb_bus_from_device(dev);

    if (dev->remote_wakeup && dev->port && dev->port->ops->wakeup) {
        dev->port->ops->wakeup(dev->port);
    }
    if (bus->ops->wakeup_endpoint) {
        bus->ops->wakeup_endpoint(bus, ep);
    }
}

/**********************/

/* generic USB device helpers (you are not forced to use them when
   writing your USB device driver, but they help handling the
   protocol)
*/

#define SETUP_STATE_IDLE  0
#define SETUP_STATE_SETUP 1
#define SETUP_STATE_DATA  2
#define SETUP_STATE_ACK   3
#define SETUP_STATE_PARAM 4

static void do_token_setup(USBDevice *s, USBPacket *p)
{
    int request, value, index;

    if (p->iov.size != 8) {
        p->status = USB_RET_STALL;
        return;
    }

    usb_packet_copy(p, s->setup_buf, p->iov.size);
    p->actual_length = 0;
    s->setup_len   = (s->setup_buf[7] << 8) | s->setup_buf[6];
    s->setup_index = 0;

    request = (s->setup_buf[0] << 8) | s->setup_buf[1];
    value   = (s->setup_buf[3] << 8) | s->setup_buf[2];
    index   = (s->setup_buf[5] << 8) | s->setup_buf[4];

    if (s->setup_buf[0] & USB_DIR_IN) {
        usb_device_handle_control(s, p, request, value, index,
                                  s->setup_len, s->data_buf);
        if (p->status == USB_RET_ASYNC) {
            s->setup_state = SETUP_STATE_SETUP;
        }
        if (p->status != USB_RET_SUCCESS) {
            return;
        }

        if (p->actual_length < s->setup_len) {
            s->setup_len = p->actual_length;
        }
        s->setup_state = SETUP_STATE_DATA;
    } else {
        if (s->setup_len > sizeof(s->data_buf)) {
            fprintf(stderr,
                "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
                s->setup_len, sizeof(s->data_buf));
            p->status = USB_RET_STALL;
            return;
        }
        if (s->setup_len == 0)
            s->setup_state = SETUP_STATE_ACK;
        else
            s->setup_state = SETUP_STATE_DATA;
    }

    p->actual_length = 8;
}

static void do_token_in(USBDevice *s, USBPacket *p)
{
    int request, value, index;

    assert(p->ep->nr == 0);

    request = (s->setup_buf[0] << 8) | s->setup_buf[1];
    value   = (s->setup_buf[3] << 8) | s->setup_buf[2];
    index   = (s->setup_buf[5] << 8) | s->setup_buf[4];

    switch(s->setup_state) {
    case SETUP_STATE_ACK:
        if (!(s->setup_buf[0] & USB_DIR_IN)) {
            usb_device_handle_control(s, p, request, value, index,
                                      s->setup_len, s->data_buf);
            if (p->status == USB_RET_ASYNC) {
                return;
            }
            s->setup_state = SETUP_STATE_IDLE;
            p->actual_length = 0;
        }
        break;

    case SETUP_STATE_DATA:
        if (s->setup_buf[0] & USB_DIR_IN) {
            int len = s->setup_len - s->setup_index;
            if (len > p->iov.size) {
                len = p->iov.size;
            }
            usb_packet_copy(p, s->data_buf + s->setup_index, len);
            s->setup_index += len;
            if (s->setup_index >= s->setup_len) {
                s->setup_state = SETUP_STATE_ACK;
            }
            return;
        }
        s->setup_state = SETUP_STATE_IDLE;
        p->status = USB_RET_STALL;
        break;

    default:
        p->status = USB_RET_STALL;
    }
}

static void do_token_out(USBDevice *s, USBPacket *p)
{
    assert(p->ep->nr == 0);

    switch(s->setup_state) {
    case SETUP_STATE_ACK:
        if (s->setup_buf[0] & USB_DIR_IN) {
            s->setup_state = SETUP_STATE_IDLE;
            /* transfer OK */
        } else {
            /* ignore additional output */
        }
        break;

    case SETUP_STATE_DATA:
        if (!(s->setup_buf[0] & USB_DIR_IN)) {
            int len = s->setup_len - s->setup_index;
            if (len > p->iov.size) {
                len = p->iov.size;
            }
            usb_packet_copy(p, s->data_buf + s->setup_index, len);
            s->setup_index += len;
            if (s->setup_index >= s->setup_len) {
                s->setup_state = SETUP_STATE_ACK;
            }
            return;
        }
        s->setup_state = SETUP_STATE_IDLE;
        p->status = USB_RET_STALL;
        break;

    default:
        p->status = USB_RET_STALL;
    }
}

static void do_parameter(USBDevice *s, USBPacket *p)
{
    int i, request, value, index;

    for (i = 0; i < 8; i++) {
        s->setup_buf[i] = p->parameter >> (i*8);
    }

    s->setup_state = SETUP_STATE_PARAM;
    s->setup_len   = (s->setup_buf[7] << 8) | s->setup_buf[6];
    s->setup_index = 0;

    request = (s->setup_buf[0] << 8) | s->setup_buf[1];
    value   = (s->setup_buf[3] << 8) | s->setup_buf[2];
    index   = (s->setup_buf[5] << 8) | s->setup_buf[4];

    if (s->setup_len > sizeof(s->data_buf)) {
        fprintf(stderr,
                "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
                s->setup_len, sizeof(s->data_buf));
        p->status = USB_RET_STALL;
        return;
    }

    if (p->pid == USB_TOKEN_OUT) {
        usb_packet_copy(p, s->data_buf, s->setup_len);
    }

    usb_device_handle_control(s, p, request, value, index,
                              s->setup_len, s->data_buf);
    if (p->status == USB_RET_ASYNC) {
        return;
    }

    if (p->actual_length < s->setup_len) {
        s->setup_len = p->actual_length;
    }
    if (p->pid == USB_TOKEN_IN) {
        p->actual_length = 0;
        usb_packet_copy(p, s->data_buf, s->setup_len);
    }
}

/* ctrl complete function for devices which use usb_generic_handle_packet and
   may return USB_RET_ASYNC from their handle_control callback. Device code
   which does this *must* call this function instead of the normal
   usb_packet_complete to complete their async control packets. */
void usb_generic_async_ctrl_complete(USBDevice *s, USBPacket *p)
{
    if (p->status < 0) {
        s->setup_state = SETUP_STATE_IDLE;
    }

    switch (s->setup_state) {
    case SETUP_STATE_SETUP:
        if (p->actual_length < s->setup_len) {
            s->setup_len = p->actual_length;
        }
        s->setup_state = SETUP_STATE_DATA;
        p->actual_length = 8;
        break;

    case SETUP_STATE_ACK:
        s->setup_state = SETUP_STATE_IDLE;
        p->actual_length = 0;
        break;

    case SETUP_STATE_PARAM:
        if (p->actual_length < s->setup_len) {
            s->setup_len = p->actual_length;
        }
        if (p->pid == USB_TOKEN_IN) {
            p->actual_length = 0;
            usb_packet_copy(p, s->data_buf, s->setup_len);
        }
        break;

    default:
        break;
    }
    usb_packet_complete(s, p);
}

/* XXX: fix overflow */
int set_usb_string(uint8_t *buf, const char *str)
{
    int len, i;
    uint8_t *q;

    q = buf;
    len = strlen(str);
    *q++ = 2 * len + 2;
    *q++ = 3;
    for(i = 0; i < len; i++) {
        *q++ = str[i];
        *q++ = 0;
    }
    return q - buf;
}

USBDevice *usb_find_device(USBPort *port, uint8_t addr)
{
    USBDevice *dev = port->dev;

    if (dev == NULL || !dev->attached || dev->state != USB_STATE_DEFAULT) {
        return NULL;
    }
    if (dev->addr == addr) {
        return dev;
    }
    return usb_device_find_device(dev, addr);
}

static void usb_process_one(USBPacket *p)
{
    USBDevice *dev = p->ep->dev;

    /*
     * Handlers expect status to be initialized to USB_RET_SUCCESS, but it
     * can be USB_RET_NAK here from a previous usb_process_one() call,
     * or USB_RET_ASYNC from going through usb_queue_one().
     */
    p->status = USB_RET_SUCCESS;

    if (p->ep->nr == 0) {
        /* control pipe */
        if (p->parameter) {
            do_parameter(dev, p);
            return;
        }
        switch (p->pid) {
        case USB_TOKEN_SETUP:
            do_token_setup(dev, p);
            break;
        case USB_TOKEN_IN:
            do_token_in(dev, p);
            break;
        case USB_TOKEN_OUT:
            do_token_out(dev, p);
            break;
        default:
            p->status = USB_RET_STALL;
        }
    } else {
        /* data pipe */
        usb_device_handle_data(dev, p);
    }
}

static void usb_queue_one(USBPacket *p)
{
    usb_packet_set_state(p, USB_PACKET_QUEUED);
    QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
    p->status = USB_RET_ASYNC;
}

/* Hand over a packet to a device for processing.  p->status ==
   USB_RET_ASYNC indicates the processing isn't finished yet, the
   driver will call usb_packet_complete() when done processing it. */
void usb_handle_packet(USBDevice *dev, USBPacket *p)
{
    if (dev == NULL) {
        p->status = USB_RET_NODEV;
        return;
    }
    assert(dev == p->ep->dev);
    assert(dev->state == USB_STATE_DEFAULT);
    usb_packet_check_state(p, USB_PACKET_SETUP);
    assert(p->ep != NULL);

    /* Submitting a new packet clears halt */
    if (p->ep->halted) {
        assert(QTAILQ_EMPTY(&p->ep->queue));
        p->ep->halted = false;
    }

    if (QTAILQ_EMPTY(&p->ep->queue) || p->ep->pipeline) {
        usb_process_one(p);
        if (p->status == USB_RET_ASYNC) {
            assert(p->ep->type != USB_ENDPOINT_XFER_ISOC);
            usb_packet_set_state(p, USB_PACKET_ASYNC);
            QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
        } else if (p->status == USB_RET_ADD_TO_QUEUE) {
            usb_queue_one(p);
        } else {
            /*
             * When pipelining is enabled usb-devices must always return async,
             * otherwise packets can complete out of order!
             */
            assert(!p->ep->pipeline || QTAILQ_EMPTY(&p->ep->queue));
            if (p->status != USB_RET_NAK) {
                usb_packet_set_state(p, USB_PACKET_COMPLETE);
            }
        }
    } else {
        usb_queue_one(p);
    }
}

void usb_packet_complete_one(USBDevice *dev, USBPacket *p)
{
    USBEndpoint *ep = p->ep;

    assert(QTAILQ_FIRST(&ep->queue) == p);
    assert(p->status != USB_RET_ASYNC && p->status != USB_RET_NAK);

    if (p->status != USB_RET_SUCCESS ||
            (p->short_not_ok && (p->actual_length < p->iov.size))) {
        ep->halted = true;
    }
    usb_packet_set_state(p, USB_PACKET_COMPLETE);
    QTAILQ_REMOVE(&ep->queue, p, queue);
    dev->port->ops->complete(dev->port, p);
}

/* Notify the controller that an async packet is complete.  This should only
   be called for packets previously deferred by returning USB_RET_ASYNC from
   handle_packet. */
void usb_packet_complete(USBDevice *dev, USBPacket *p)
{
    USBEndpoint *ep = p->ep;

    usb_packet_check_state(p, USB_PACKET_ASYNC);
    usb_packet_complete_one(dev, p);

    while (!QTAILQ_EMPTY(&ep->queue)) {
        p = QTAILQ_FIRST(&ep->queue);
        if (ep->halted) {
            /* Empty the queue on a halt */
            p->status = USB_RET_REMOVE_FROM_QUEUE;
            dev->port->ops->complete(dev->port, p);
            continue;
        }
        if (p->state == USB_PACKET_ASYNC) {
            break;
        }
        usb_packet_check_state(p, USB_PACKET_QUEUED);
        usb_process_one(p);
        if (p->status == USB_RET_ASYNC) {
            usb_packet_set_state(p, USB_PACKET_ASYNC);
            break;
        }
        usb_packet_complete_one(ep->dev, p);
    }
}

/* Cancel an active packet.  The packed must have been deferred by
   returning USB_RET_ASYNC from handle_packet, and not yet
   completed.  */
void usb_cancel_packet(USBPacket * p)
{
    bool callback = (p->state == USB_PACKET_ASYNC);
    assert(usb_packet_is_inflight(p));
    usb_packet_set_state(p, USB_PACKET_CANCELED);
    QTAILQ_REMOVE(&p->ep->queue, p, queue);
    if (callback) {
        usb_device_cancel_packet(p->ep->dev, p);
    }
}


void usb_packet_init(USBPacket *p)
{
    qemu_iovec_init(&p->iov, 1);
}

static const char *usb_packet_state_name(USBPacketState state)
{
    static const char *name[] = {
        [USB_PACKET_UNDEFINED] = "undef",
        [USB_PACKET_SETUP]     = "setup",
        [USB_PACKET_QUEUED]    = "queued",
        [USB_PACKET_ASYNC]     = "async",
        [USB_PACKET_COMPLETE]  = "complete",
        [USB_PACKET_CANCELED]  = "canceled",
    };
    if (state < ARRAY_SIZE(name)) {
        return name[state];
    }
    return "INVALID";
}

void usb_packet_check_state(USBPacket *p, USBPacketState expected)
{
    USBDevice *dev;
    USBBus *bus;

    if (p->state == expected) {
        return;
    }
    dev = p->ep->dev;
    bus = usb_bus_from_device(dev);
    trace_usb_packet_state_fault(bus->busnr, dev->port->path, p->ep->nr, p,
                                 usb_packet_state_name(p->state),
                                 usb_packet_state_name(expected));
    assert(!"usb packet state check failed");
}

void usb_packet_set_state(USBPacket *p, USBPacketState state)
{
    if (p->ep) {
        USBDevice *dev = p->ep->dev;
        USBBus *bus = usb_bus_from_device(dev);
        trace_usb_packet_state_change(bus->busnr, dev->port->path, p->ep->nr, p,
                                      usb_packet_state_name(p->state),
                                      usb_packet_state_name(state));
    } else {
        trace_usb_packet_state_change(-1, "", -1, p,
                                      usb_packet_state_name(p->state),
                                      usb_packet_state_name(state));
    }
    p->state = state;
}

void usb_packet_setup(USBPacket *p, int pid, USBEndpoint *ep, uint64_t id,
                      bool short_not_ok, bool int_req)
{
    assert(!usb_packet_is_inflight(p));
    assert(p->iov.iov != NULL);
    p->id = id;
    p->pid = pid;
    p->ep = ep;
    p->status = USB_RET_SUCCESS;
    p->actual_length = 0;
    p->parameter = 0;
    p->short_not_ok = short_not_ok;
    p->int_req = int_req;
    p->combined = NULL;
    qemu_iovec_reset(&p->iov);
    usb_packet_set_state(p, USB_PACKET_SETUP);
}

void usb_packet_addbuf(USBPacket *p, void *ptr, size_t len)
{
    qemu_iovec_add(&p->iov, ptr, len);
}

void usb_packet_copy(USBPacket *p, void *ptr, size_t bytes)
{
    assert(p->actual_length >= 0);
    assert(p->actual_length + bytes <= p->iov.size);
    switch (p->pid) {
    case USB_TOKEN_SETUP:
    case USB_TOKEN_OUT:
        iov_to_buf(p->iov.iov, p->iov.niov, p->actual_length, ptr, bytes);
        break;
    case USB_TOKEN_IN:
        iov_from_buf(p->iov.iov, p->iov.niov, p->actual_length, ptr, bytes);
        break;
    default:
        fprintf(stderr, "%s: invalid pid: %x\n", __func__, p->pid);
        abort();
    }
    p->actual_length += bytes;
}

void usb_packet_skip(USBPacket *p, size_t bytes)
{
    assert(p->actual_length >= 0);
    assert(p->actual_length + bytes <= p->iov.size);
    if (p->pid == USB_TOKEN_IN) {
        iov_memset(p->iov.iov, p->iov.niov, p->actual_length, 0, bytes);
    }
    p->actual_length += bytes;
}

void usb_packet_cleanup(USBPacket *p)
{
    assert(!usb_packet_is_inflight(p));
    qemu_iovec_destroy(&p->iov);
}

void usb_ep_reset(USBDevice *dev)
{
    int ep;

    dev->ep_ctl.nr = 0;
    dev->ep_ctl.type = USB_ENDPOINT_XFER_CONTROL;
    dev->ep_ctl.ifnum = 0;
    dev->ep_ctl.dev = dev;
    dev->ep_ctl.pipeline = false;
    for (ep = 0; ep < USB_MAX_ENDPOINTS; ep++) {
        dev->ep_in[ep].nr = ep + 1;
        dev->ep_out[ep].nr = ep + 1;
        dev->ep_in[ep].pid = USB_TOKEN_IN;
        dev->ep_out[ep].pid = USB_TOKEN_OUT;
        dev->ep_in[ep].type = USB_ENDPOINT_XFER_INVALID;
        dev->ep_out[ep].type = USB_ENDPOINT_XFER_INVALID;
        dev->ep_in[ep].ifnum = USB_INTERFACE_INVALID;
        dev->ep_out[ep].ifnum = USB_INTERFACE_INVALID;
        dev->ep_in[ep].dev = dev;
        dev->ep_out[ep].dev = dev;
        dev->ep_in[ep].pipeline = false;
        dev->ep_out[ep].pipeline = false;
    }
}

void usb_ep_init(USBDevice *dev)
{
    int ep;

    usb_ep_reset(dev);
    QTAILQ_INIT(&dev->ep_ctl.queue);
    for (ep = 0; ep < USB_MAX_ENDPOINTS; ep++) {
        QTAILQ_INIT(&dev->ep_in[ep].queue);
        QTAILQ_INIT(&dev->ep_out[ep].queue);
    }
}

void usb_ep_dump(USBDevice *dev)
{
    static const char *tname[] = {
        [USB_ENDPOINT_XFER_CONTROL] = "control",
        [USB_ENDPOINT_XFER_ISOC]    = "isoc",
        [USB_ENDPOINT_XFER_BULK]    = "bulk",
        [USB_ENDPOINT_XFER_INT]     = "int",
    };
    int ifnum, ep, first;

    fprintf(stderr, "Device \"%s\", config %d\n",
            dev->product_desc, dev->configuration);
    for (ifnum = 0; ifnum < 16; ifnum++) {
        first = 1;
        for (ep = 0; ep < USB_MAX_ENDPOINTS; ep++) {
            if (dev->ep_in[ep].type != USB_ENDPOINT_XFER_INVALID &&
                dev->ep_in[ep].ifnum == ifnum) {
                if (first) {
                    first = 0;
                    fprintf(stderr, "  Interface %d, alternative %d\n",
                            ifnum, dev->altsetting[ifnum]);
                }
                fprintf(stderr, "    Endpoint %d, IN, %s, %d max\n", ep,
                        tname[dev->ep_in[ep].type],
                        dev->ep_in[ep].max_packet_size);
            }
            if (dev->ep_out[ep].type != USB_ENDPOINT_XFER_INVALID &&
                dev->ep_out[ep].ifnum == ifnum) {
                if (first) {
                    first = 0;
                    fprintf(stderr, "  Interface %d, alternative %d\n",
                            ifnum, dev->altsetting[ifnum]);
                }
                fprintf(stderr, "    Endpoint %d, OUT, %s, %d max\n", ep,
                        tname[dev->ep_out[ep].type],
                        dev->ep_out[ep].max_packet_size);
            }
        }
    }
    fprintf(stderr, "--\n");
}

struct USBEndpoint *usb_ep_get(USBDevice *dev, int pid, int ep)
{
    struct USBEndpoint *eps;

    if (dev == NULL) {
        return NULL;
    }
    eps = (pid == USB_TOKEN_IN) ? dev->ep_in : dev->ep_out;
    if (ep == 0) {
        return &dev->ep_ctl;
    }
    assert(pid == USB_TOKEN_IN || pid == USB_TOKEN_OUT);
    assert(ep > 0 && ep <= USB_MAX_ENDPOINTS);
    return eps + ep - 1;
}

uint8_t usb_ep_get_type(USBDevice *dev, int pid, int ep)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    return uep->type;
}

void usb_ep_set_type(USBDevice *dev, int pid, int ep, uint8_t type)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    uep->type = type;
}

uint8_t usb_ep_get_ifnum(USBDevice *dev, int pid, int ep)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    return uep->ifnum;
}

void usb_ep_set_ifnum(USBDevice *dev, int pid, int ep, uint8_t ifnum)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    uep->ifnum = ifnum;
}

void usb_ep_set_max_packet_size(USBDevice *dev, int pid, int ep,
                                uint16_t raw)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    int size, microframes;

    size = raw & 0x7ff;
    switch ((raw >> 11) & 3) {
    case 1:
        microframes = 2;
        break;
    case 2:
        microframes = 3;
        break;
    default:
        microframes = 1;
        break;
    }
    uep->max_packet_size = size * microframes;
}

int usb_ep_get_max_packet_size(USBDevice *dev, int pid, int ep)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    return uep->max_packet_size;
}

void usb_ep_set_pipeline(USBDevice *dev, int pid, int ep, bool enabled)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    uep->pipeline = enabled;
}

USBPacket *usb_ep_find_packet_by_id(USBDevice *dev, int pid, int ep,
                                    uint64_t id)
{
    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
    USBPacket *p;

    while ((p = QTAILQ_FIRST(&uep->queue)) != NULL) {
        if (p->id == id) {
            return p;
        }
    }

    return NULL;
}