Archipelago » qemu

/*

 * USB UHCI controller emulation

 *

 * Copyright (c) 2005 Fabrice Bellard

 *

 * Copyright (c) 2008 Max Krasnyansky

 *     Magor rewrite of the UHCI data structures parser and frame processor

 *     Support for fully async operation and multiple outstanding transactions

 *

 * 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 "hw/hw.h"

#include "hw/usb.h"

#include "hw/pci/pci.h"

#include "qemu/timer.h"

#include "qemu/iov.h"

#include "sysemu/dma.h"

#include "trace.h"

//#define DEBUG

//#define DEBUG_DUMP_DATA

#define UHCI_CMD_FGR      (1 << 4)

#define UHCI_CMD_EGSM     (1 << 3)

#define UHCI_CMD_GRESET   (1 << 2)

#define UHCI_CMD_HCRESET  (1 << 1)

#define UHCI_CMD_RS       (1 << 0)

#define UHCI_STS_HCHALTED (1 << 5)

#define UHCI_STS_HCPERR   (1 << 4)

#define UHCI_STS_HSERR    (1 << 3)

#define UHCI_STS_RD       (1 << 2)

#define UHCI_STS_USBERR   (1 << 1)

#define UHCI_STS_USBINT   (1 << 0)

#define TD_CTRL_SPD     (1 << 29)

#define TD_CTRL_ERROR_SHIFT  27

#define TD_CTRL_IOS     (1 << 25)

#define TD_CTRL_IOC     (1 << 24)

#define TD_CTRL_ACTIVE  (1 << 23)

#define TD_CTRL_STALL   (1 << 22)

#define TD_CTRL_BABBLE  (1 << 20)

#define TD_CTRL_NAK     (1 << 19)

#define TD_CTRL_TIMEOUT (1 << 18)

#define UHCI_PORT_SUSPEND (1 << 12)

#define UHCI_PORT_RESET (1 << 9)

#define UHCI_PORT_LSDA  (1 << 8)

#define UHCI_PORT_RD    (1 << 6)

#define UHCI_PORT_ENC   (1 << 3)

#define UHCI_PORT_EN    (1 << 2)

#define UHCI_PORT_CSC   (1 << 1)

#define UHCI_PORT_CCS   (1 << 0)

#define UHCI_PORT_READ_ONLY    (0x1bb)

#define UHCI_PORT_WRITE_CLEAR  (UHCI_PORT_CSC | UHCI_PORT_ENC)

#define FRAME_TIMER_FREQ 1000

#define FRAME_MAX_LOOPS  256

/* Must be large enough to handle 10 frame delay for initial isoc requests */

#define QH_VALID         32

#define MAX_FRAMES_PER_TICK    (QH_VALID / 2)

#define NB_PORTS 2

enum {

    TD_RESULT_STOP_FRAME = 10,

    TD_RESULT_COMPLETE,

    TD_RESULT_NEXT_QH,

    TD_RESULT_ASYNC_START,

    TD_RESULT_ASYNC_CONT,

};

typedef struct UHCIState UHCIState;

typedef struct UHCIAsync UHCIAsync;

typedef struct UHCIQueue UHCIQueue;

typedef struct UHCIInfo UHCIInfo;

typedef struct UHCIPCIDeviceClass UHCIPCIDeviceClass;

struct UHCIInfo {

    const char *name;

    uint16_t   vendor_id;

    uint16_t   device_id;

    uint8_t    revision;

    uint8_t    irq_pin;

    int        (*initfn)(PCIDevice *dev);

    bool       unplug;

};

struct UHCIPCIDeviceClass {

    PCIDeviceClass parent_class;

    UHCIInfo       info;

};

/* 

 * Pending async transaction.

 * 'packet' must be the first field because completion

 * handler does "(UHCIAsync *) pkt" cast.

 */

struct UHCIAsync {

    USBPacket packet;

    QEMUSGList sgl;

    UHCIQueue *queue;

    QTAILQ_ENTRY(UHCIAsync) next;

    uint32_t  td_addr;

    uint8_t   done;

};

struct UHCIQueue {

    uint32_t  qh_addr;

    uint32_t  token;

    UHCIState *uhci;

    USBEndpoint *ep;

    QTAILQ_ENTRY(UHCIQueue) next;

    QTAILQ_HEAD(asyncs_head, UHCIAsync) asyncs;

    int8_t    valid;

};

typedef struct UHCIPort {

    USBPort port;

    uint16_t ctrl;

} UHCIPort;

struct UHCIState {

    PCIDevice dev;

    MemoryRegion io_bar;

    USBBus bus; /* Note unused when we're a companion controller */

    uint16_t cmd; /* cmd register */

    uint16_t status;

    uint16_t intr; /* interrupt enable register */

    uint16_t frnum; /* frame number */

    uint32_t fl_base_addr; /* frame list base address */

    uint8_t sof_timing;

    uint8_t status2; /* bit 0 and 1 are used to generate UHCI_STS_USBINT */

    int64_t expire_time;

    QEMUTimer *frame_timer;

    QEMUBH *bh;

    uint32_t frame_bytes;

    uint32_t frame_bandwidth;

    bool completions_only;

    UHCIPort ports[NB_PORTS];

    /* Interrupts that should be raised at the end of the current frame.  */

    uint32_t pending_int_mask;

    int irq_pin;

    /* Active packets */

    QTAILQ_HEAD(, UHCIQueue) queues;

    uint8_t num_ports_vmstate;

    /* Properties */

    char *masterbus;

    uint32_t firstport;

    uint32_t maxframes;

};

typedef struct UHCI_TD {

    uint32_t link;

    uint32_t ctrl; /* see TD_CTRL_xxx */

    uint32_t token;

    uint32_t buffer;

} UHCI_TD;

typedef struct UHCI_QH {

    uint32_t link;

    uint32_t el_link;

} UHCI_QH;

static void uhci_async_cancel(UHCIAsync *async);

static void uhci_queue_fill(UHCIQueue *q, UHCI_TD *td);

static inline int32_t uhci_queue_token(UHCI_TD *td)

{

    if ((td->token & (0xf << 15)) == 0) {

        /* ctrl ep, cover ep and dev, not pid! */

        return td->token & 0x7ff00;

    } else {

        /* covers ep, dev, pid -> identifies the endpoint */

        return td->token & 0x7ffff;

    }

}

static UHCIQueue *uhci_queue_new(UHCIState *s, uint32_t qh_addr, UHCI_TD *td,

                                 USBEndpoint *ep)

{

    UHCIQueue *queue;

    queue = g_new0(UHCIQueue, 1);

    queue->uhci = s;

    queue->qh_addr = qh_addr;

    queue->token = uhci_queue_token(td);

    queue->ep = ep;

    QTAILQ_INIT(&queue->asyncs);

    QTAILQ_INSERT_HEAD(&s->queues, queue, next);

    queue->valid = QH_VALID;

    trace_usb_uhci_queue_add(queue->token);

    return queue;

}

static void uhci_queue_free(UHCIQueue *queue, const char *reason)

{

    UHCIState *s = queue->uhci;

    UHCIAsync *async;

    while (!QTAILQ_EMPTY(&queue->asyncs)) {

        async = QTAILQ_FIRST(&queue->asyncs);

        uhci_async_cancel(async);

    }

    usb_device_ep_stopped(queue->ep->dev, queue->ep);

    trace_usb_uhci_queue_del(queue->token, reason);

    QTAILQ_REMOVE(&s->queues, queue, next);

    g_free(queue);

}

static UHCIQueue *uhci_queue_find(UHCIState *s, UHCI_TD *td)

{

    uint32_t token = uhci_queue_token(td);

    UHCIQueue *queue;

    QTAILQ_FOREACH(queue, &s->queues, next) {

        if (queue->token == token) {

            return queue;

        }

    }

    return NULL;

}

static bool uhci_queue_verify(UHCIQueue *queue, uint32_t qh_addr, UHCI_TD *td,

                              uint32_t td_addr, bool queuing)

{

    UHCIAsync *first = QTAILQ_FIRST(&queue->asyncs);

    return queue->qh_addr == qh_addr &&

           queue->token == uhci_queue_token(td) &&

           (queuing || !(td->ctrl & TD_CTRL_ACTIVE) || first == NULL ||

            first->td_addr == td_addr);

}

static UHCIAsync *uhci_async_alloc(UHCIQueue *queue, uint32_t td_addr)

{

    UHCIAsync *async = g_new0(UHCIAsync, 1);

    async->queue = queue;

    async->td_addr = td_addr;

    usb_packet_init(&async->packet);

    pci_dma_sglist_init(&async->sgl, &queue->uhci->dev, 1);

    trace_usb_uhci_packet_add(async->queue->token, async->td_addr);

    return async;

}

static void uhci_async_free(UHCIAsync *async)

{

    trace_usb_uhci_packet_del(async->queue->token, async->td_addr);

    usb_packet_cleanup(&async->packet);

    qemu_sglist_destroy(&async->sgl);

    g_free(async);

}

static void uhci_async_link(UHCIAsync *async)

{

    UHCIQueue *queue = async->queue;

    QTAILQ_INSERT_TAIL(&queue->asyncs, async, next);

    trace_usb_uhci_packet_link_async(async->queue->token, async->td_addr);

}

static void uhci_async_unlink(UHCIAsync *async)

{

    UHCIQueue *queue = async->queue;

    QTAILQ_REMOVE(&queue->asyncs, async, next);

    trace_usb_uhci_packet_unlink_async(async->queue->token, async->td_addr);

}

static void uhci_async_cancel(UHCIAsync *async)

{

    uhci_async_unlink(async);

    trace_usb_uhci_packet_cancel(async->queue->token, async->td_addr,

                                 async->done);

    if (!async->done)

        usb_cancel_packet(&async->packet);

    usb_packet_unmap(&async->packet, &async->sgl);

    uhci_async_free(async);

}

/*

 * Mark all outstanding async packets as invalid.

 * This is used for canceling them when TDs are removed by the HCD.

 */

static void uhci_async_validate_begin(UHCIState *s)

{

    UHCIQueue *queue;

    QTAILQ_FOREACH(queue, &s->queues, next) {

        queue->valid--;

    }

}

/*

 * Cancel async packets that are no longer valid

 */

static void uhci_async_validate_end(UHCIState *s)

{

    UHCIQueue *queue, *n;

    QTAILQ_FOREACH_SAFE(queue, &s->queues, next, n) {

        if (!queue->valid) {

            uhci_queue_free(queue, "validate-end");

        }

    }

}

static void uhci_async_cancel_device(UHCIState *s, USBDevice *dev)

{

    UHCIQueue *queue, *n;

    QTAILQ_FOREACH_SAFE(queue, &s->queues, next, n) {

        if (queue->ep->dev == dev) {

            uhci_queue_free(queue, "cancel-device");

        }

    }

}

static void uhci_async_cancel_all(UHCIState *s)

{

    UHCIQueue *queue, *nq;

    QTAILQ_FOREACH_SAFE(queue, &s->queues, next, nq) {

        uhci_queue_free(queue, "cancel-all");

    }

}

static UHCIAsync *uhci_async_find_td(UHCIState *s, uint32_t td_addr)

{

    UHCIQueue *queue;

    UHCIAsync *async;

    QTAILQ_FOREACH(queue, &s->queues, next) {

        QTAILQ_FOREACH(async, &queue->asyncs, next) {

            if (async->td_addr == td_addr) {

                return async;

            }

        }

    }

    return NULL;

}

static void uhci_update_irq(UHCIState *s)

{

    int level;

    if (((s->status2 & 1) && (s->intr & (1 << 2))) ||

        ((s->status2 & 2) && (s->intr & (1 << 3))) ||

        ((s->status & UHCI_STS_USBERR) && (s->intr & (1 << 0))) ||

        ((s->status & UHCI_STS_RD) && (s->intr & (1 << 1))) ||

        (s->status & UHCI_STS_HSERR) ||

        (s->status & UHCI_STS_HCPERR)) {

        level = 1;

    } else {

        level = 0;

    }

    qemu_set_irq(s->dev.irq[s->irq_pin], level);

}

static void uhci_reset(void *opaque)

{

    UHCIState *s = opaque;

    uint8_t *pci_conf;

    int i;

    UHCIPort *port;

    trace_usb_uhci_reset();

    pci_conf = s->dev.config;

    pci_conf[0x6a] = 0x01; /* usb clock */

    pci_conf[0x6b] = 0x00;

    s->cmd = 0;

    s->status = 0;

    s->status2 = 0;

    s->intr = 0;

    s->fl_base_addr = 0;

    s->sof_timing = 64;

    for(i = 0; i < NB_PORTS; i++) {

        port = &s->ports[i];

        port->ctrl = 0x0080;

        if (port->port.dev && port->port.dev->attached) {

            usb_port_reset(&port->port);

        }

    }

    uhci_async_cancel_all(s);

    qemu_bh_cancel(s->bh);

    uhci_update_irq(s);

}

static const VMStateDescription vmstate_uhci_port = {

    .name = "uhci port",

    .version_id = 1,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .fields      = (VMStateField []) {

        VMSTATE_UINT16(ctrl, UHCIPort),

        VMSTATE_END_OF_LIST()

    }

};

static int uhci_post_load(void *opaque, int version_id)

{

    UHCIState *s = opaque;

    if (version_id < 2) {

        s->expire_time = qemu_get_clock_ns(vm_clock) +

            (get_ticks_per_sec() / FRAME_TIMER_FREQ);

    }

    return 0;

}

static const VMStateDescription vmstate_uhci = {

    .name = "uhci",

    .version_id = 3,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .post_load = uhci_post_load,

    .fields      = (VMStateField []) {

        VMSTATE_PCI_DEVICE(dev, UHCIState),

        VMSTATE_UINT8_EQUAL(num_ports_vmstate, UHCIState),

        VMSTATE_STRUCT_ARRAY(ports, UHCIState, NB_PORTS, 1,

                             vmstate_uhci_port, UHCIPort),

        VMSTATE_UINT16(cmd, UHCIState),

        VMSTATE_UINT16(status, UHCIState),

        VMSTATE_UINT16(intr, UHCIState),

        VMSTATE_UINT16(frnum, UHCIState),

        VMSTATE_UINT32(fl_base_addr, UHCIState),

        VMSTATE_UINT8(sof_timing, UHCIState),

        VMSTATE_UINT8(status2, UHCIState),

        VMSTATE_TIMER(frame_timer, UHCIState),

        VMSTATE_INT64_V(expire_time, UHCIState, 2),

        VMSTATE_UINT32_V(pending_int_mask, UHCIState, 3),

        VMSTATE_END_OF_LIST()

    }

};

static void uhci_port_write(void *opaque, hwaddr addr,

                            uint64_t val, unsigned size)

{

    UHCIState *s = opaque;

    trace_usb_uhci_mmio_writew(addr, val);

    switch(addr) {

    case 0x00:

        if ((val & UHCI_CMD_RS) && !(s->cmd & UHCI_CMD_RS)) {

            /* start frame processing */

            trace_usb_uhci_schedule_start();

            s->expire_time = qemu_get_clock_ns(vm_clock) +

                (get_ticks_per_sec() / FRAME_TIMER_FREQ);

            qemu_mod_timer(s->frame_timer, s->expire_time);

            s->status &= ~UHCI_STS_HCHALTED;

        } else if (!(val & UHCI_CMD_RS)) {

            s->status |= UHCI_STS_HCHALTED;

        }

        if (val & UHCI_CMD_GRESET) {

            UHCIPort *port;

            int i;

            /* send reset on the USB bus */

            for(i = 0; i < NB_PORTS; i++) {

                port = &s->ports[i];

                usb_device_reset(port->port.dev);

            }

            uhci_reset(s);

            return;

        }

        if (val & UHCI_CMD_HCRESET) {

            uhci_reset(s);

            return;

        }

        s->cmd = val;

        break;

    case 0x02:

        s->status &= ~val;

        /* XXX: the chip spec is not coherent, so we add a hidden

           register to distinguish between IOC and SPD */

        if (val & UHCI_STS_USBINT)

            s->status2 = 0;

        uhci_update_irq(s);

        break;

    case 0x04:

        s->intr = val;

        uhci_update_irq(s);

        break;

    case 0x06:

        if (s->status & UHCI_STS_HCHALTED)

            s->frnum = val & 0x7ff;

        break;

    case 0x08:

        s->fl_base_addr &= 0xffff0000;

        s->fl_base_addr |= val & ~0xfff;

        break;

    case 0x0a:

        s->fl_base_addr &= 0x0000ffff;

        s->fl_base_addr |= (val << 16);

        break;

    case 0x0c:

        s->sof_timing = val & 0xff;

        break;

    case 0x10 ... 0x1f:

        {

            UHCIPort *port;

            USBDevice *dev;

            int n;

            n = (addr >> 1) & 7;

            if (n >= NB_PORTS)

                return;

            port = &s->ports[n];

            dev = port->port.dev;

            if (dev && dev->attached) {

                /* port reset */

                if ( (val & UHCI_PORT_RESET) &&

                     !(port->ctrl & UHCI_PORT_RESET) ) {

                    usb_device_reset(dev);

                }

            }

            port->ctrl &= UHCI_PORT_READ_ONLY;

            /* enabled may only be set if a device is connected */

            if (!(port->ctrl & UHCI_PORT_CCS)) {

                val &= ~UHCI_PORT_EN;

            }

            port->ctrl |= (val & ~UHCI_PORT_READ_ONLY);

            /* some bits are reset when a '1' is written to them */

            port->ctrl &= ~(val & UHCI_PORT_WRITE_CLEAR);

        }

        break;

    }

}

static uint64_t uhci_port_read(void *opaque, hwaddr addr, unsigned size)

{

    UHCIState *s = opaque;

    uint32_t val;

    switch(addr) {

    case 0x00:

        val = s->cmd;

        break;

    case 0x02:

        val = s->status;

        break;

    case 0x04:

        val = s->intr;

        break;

    case 0x06:

        val = s->frnum;

        break;

    case 0x08:

        val = s->fl_base_addr & 0xffff;

        break;

    case 0x0a:

        val = (s->fl_base_addr >> 16) & 0xffff;

        break;

    case 0x0c:

        val = s->sof_timing;

        break;

    case 0x10 ... 0x1f:

        {

            UHCIPort *port;

            int n;

            n = (addr >> 1) & 7;

            if (n >= NB_PORTS)

                goto read_default;

            port = &s->ports[n];

            val = port->ctrl;

        }

        break;

    default:

    read_default:

        val = 0xff7f; /* disabled port */

        break;

    }

    trace_usb_uhci_mmio_readw(addr, val);

    return val;

}

/* signal resume if controller suspended */

static void uhci_resume (void *opaque)

{

    UHCIState *s = (UHCIState *)opaque;

    if (!s)

        return;

    if (s->cmd & UHCI_CMD_EGSM) {

        s->cmd |= UHCI_CMD_FGR;

        s->status |= UHCI_STS_RD;

        uhci_update_irq(s);

    }

}

static void uhci_attach(USBPort *port1)

{

    UHCIState *s = port1->opaque;

    UHCIPort *port = &s->ports[port1->index];

    /* set connect status */

    port->ctrl |= UHCI_PORT_CCS | UHCI_PORT_CSC;

    /* update speed */

    if (port->port.dev->speed == USB_SPEED_LOW) {

        port->ctrl |= UHCI_PORT_LSDA;

    } else {

        port->ctrl &= ~UHCI_PORT_LSDA;

    }

    uhci_resume(s);

}

static void uhci_detach(USBPort *port1)

{

    UHCIState *s = port1->opaque;

    UHCIPort *port = &s->ports[port1->index];

    uhci_async_cancel_device(s, port1->dev);

    /* set connect status */

    if (port->ctrl & UHCI_PORT_CCS) {

        port->ctrl &= ~UHCI_PORT_CCS;

        port->ctrl |= UHCI_PORT_CSC;

    }

    /* disable port */

    if (port->ctrl & UHCI_PORT_EN) {

        port->ctrl &= ~UHCI_PORT_EN;

        port->ctrl |= UHCI_PORT_ENC;

    }

    uhci_resume(s);

}

static void uhci_child_detach(USBPort *port1, USBDevice *child)

{

    UHCIState *s = port1->opaque;

    uhci_async_cancel_device(s, child);

}

static void uhci_wakeup(USBPort *port1)

{

    UHCIState *s = port1->opaque;

    UHCIPort *port = &s->ports[port1->index];

    if (port->ctrl & UHCI_PORT_SUSPEND && !(port->ctrl & UHCI_PORT_RD)) {

        port->ctrl |= UHCI_PORT_RD;

        uhci_resume(s);

    }

}

static USBDevice *uhci_find_device(UHCIState *s, uint8_t addr)

{

    USBDevice *dev;

    int i;

    for (i = 0; i < NB_PORTS; i++) {

        UHCIPort *port = &s->ports[i];

        if (!(port->ctrl & UHCI_PORT_EN)) {

            continue;

        }

        dev = usb_find_device(&port->port, addr);

        if (dev != NULL) {

            return dev;

        }

    }

    return NULL;

}

static void uhci_read_td(UHCIState *s, UHCI_TD *td, uint32_t link)

{

    pci_dma_read(&s->dev, link & ~0xf, td, sizeof(*td));

    le32_to_cpus(&td->link);

    le32_to_cpus(&td->ctrl);

    le32_to_cpus(&td->token);

    le32_to_cpus(&td->buffer);

}

static int uhci_handle_td_error(UHCIState *s, UHCI_TD *td, uint32_t td_addr,

                                int status, uint32_t *int_mask)

{

    uint32_t queue_token = uhci_queue_token(td);

    int ret;

    switch (status) {

    case USB_RET_NAK:

        td->ctrl |= TD_CTRL_NAK;

        return TD_RESULT_NEXT_QH;

    case USB_RET_STALL:

        td->ctrl |= TD_CTRL_STALL;

        trace_usb_uhci_packet_complete_stall(queue_token, td_addr);

        ret = TD_RESULT_NEXT_QH;

        break;

    case USB_RET_BABBLE:

        td->ctrl |= TD_CTRL_BABBLE | TD_CTRL_STALL;

        /* frame interrupted */

        trace_usb_uhci_packet_complete_babble(queue_token, td_addr);

        ret = TD_RESULT_STOP_FRAME;

        break;

    case USB_RET_IOERROR:

    case USB_RET_NODEV:

    default:

        td->ctrl |= TD_CTRL_TIMEOUT;

        td->ctrl &= ~(3 << TD_CTRL_ERROR_SHIFT);

        trace_usb_uhci_packet_complete_error(queue_token, td_addr);

        ret = TD_RESULT_NEXT_QH;

        break;

    }

    td->ctrl &= ~TD_CTRL_ACTIVE;

    s->status |= UHCI_STS_USBERR;

    if (td->ctrl & TD_CTRL_IOC) {

        *int_mask |= 0x01;

    }

    uhci_update_irq(s);

    return ret;

}

static int uhci_complete_td(UHCIState *s, UHCI_TD *td, UHCIAsync *async, uint32_t *int_mask)

{

    int len = 0, max_len;

    uint8_t pid;

    max_len = ((td->token >> 21) + 1) & 0x7ff;

    pid = td->token & 0xff;

    if (td->ctrl & TD_CTRL_IOS)

        td->ctrl &= ~TD_CTRL_ACTIVE;

    if (async->packet.status != USB_RET_SUCCESS) {

        return uhci_handle_td_error(s, td, async->td_addr,

                                    async->packet.status, int_mask);

    }

    len = async->packet.actual_length;

    td->ctrl = (td->ctrl & ~0x7ff) | ((len - 1) & 0x7ff);

    /* The NAK bit may have been set by a previous frame, so clear it

       here.  The docs are somewhat unclear, but win2k relies on this

       behavior.  */

    td->ctrl &= ~(TD_CTRL_ACTIVE | TD_CTRL_NAK);

    if (td->ctrl & TD_CTRL_IOC)

        *int_mask |= 0x01;

    if (pid == USB_TOKEN_IN) {

        if ((td->ctrl & TD_CTRL_SPD) && len < max_len) {

            *int_mask |= 0x02;

            /* short packet: do not update QH */

            trace_usb_uhci_packet_complete_shortxfer(async->queue->token,

                                                     async->td_addr);

            return TD_RESULT_NEXT_QH;

        }

    }

    /* success */

    trace_usb_uhci_packet_complete_success(async->queue->token,

                                           async->td_addr);

    return TD_RESULT_COMPLETE;

}

static int uhci_handle_td(UHCIState *s, UHCIQueue *q, uint32_t qh_addr,

                          UHCI_TD *td, uint32_t td_addr, uint32_t *int_mask)

{

    int ret, max_len;

    bool spd;

    bool queuing = (q != NULL);

    uint8_t pid = td->token & 0xff;

    UHCIAsync *async = uhci_async_find_td(s, td_addr);

    if (async) {

        if (uhci_queue_verify(async->queue, qh_addr, td, td_addr, queuing)) {

            assert(q == NULL || q == async->queue);

            q = async->queue;

        } else {

            uhci_queue_free(async->queue, "guest re-used pending td");

            async = NULL;

        }

    }

    if (q == NULL) {

        q = uhci_queue_find(s, td);

        if (q && !uhci_queue_verify(q, qh_addr, td, td_addr, queuing)) {

            uhci_queue_free(q, "guest re-used qh");

            q = NULL;

        }

    }

    if (q) {

        q->valid = QH_VALID;

    }

    /* Is active ? */

    if (!(td->ctrl & TD_CTRL_ACTIVE)) {

        if (async) {

            /* Guest marked a pending td non-active, cancel the queue */

            uhci_queue_free(async->queue, "pending td non-active");

        }

        /*

         * ehci11d spec page 22: "Even if the Active bit in the TD is already

         * cleared when the TD is fetched ... an IOC interrupt is generated"

         */

        if (td->ctrl & TD_CTRL_IOC) {

                *int_mask |= 0x01;

        }

        return TD_RESULT_NEXT_QH;

    }

    if (async) {

        if (queuing) {

            /* we are busy filling the queue, we are not prepared

               to consume completed packages then, just leave them

               in async state */

            return TD_RESULT_ASYNC_CONT;

        }

        if (!async->done) {

            UHCI_TD last_td;

            UHCIAsync *last = QTAILQ_LAST(&async->queue->asyncs, asyncs_head);

            /*

             * While we are waiting for the current td to complete, the guest

             * may have added more tds to the queue. Note we re-read the td

             * rather then caching it, as we want to see guest made changes!

             */

            uhci_read_td(s, &last_td, last->td_addr);

            uhci_queue_fill(async->queue, &last_td);

            return TD_RESULT_ASYNC_CONT;

        }

        uhci_async_unlink(async);

        goto done;

    }

    if (s->completions_only) {

        return TD_RESULT_ASYNC_CONT;

    }

    /* Allocate new packet */

    if (q == NULL) {

        USBDevice *dev = uhci_find_device(s, (td->token >> 8) & 0x7f);

        USBEndpoint *ep = usb_ep_get(dev, pid, (td->token >> 15) & 0xf);

        if (ep == NULL) {

            return uhci_handle_td_error(s, td, td_addr, USB_RET_NODEV,

                                        int_mask);

        }

        q = uhci_queue_new(s, qh_addr, td, ep);

    }

    async = uhci_async_alloc(q, td_addr);

    max_len = ((td->token >> 21) + 1) & 0x7ff;

    spd = (pid == USB_TOKEN_IN && (td->ctrl & TD_CTRL_SPD) != 0);

    usb_packet_setup(&async->packet, pid, q->ep, td_addr, spd,

                     (td->ctrl & TD_CTRL_IOC) != 0);

    qemu_sglist_add(&async->sgl, td->buffer, max_len);

    usb_packet_map(&async->packet, &async->sgl);

    switch(pid) {

    case USB_TOKEN_OUT:

    case USB_TOKEN_SETUP:

        usb_handle_packet(q->ep->dev, &async->packet);

        if (async->packet.status == USB_RET_SUCCESS) {

            async->packet.actual_length = max_len;

        }

        break;

    case USB_TOKEN_IN:

        usb_handle_packet(q->ep->dev, &async->packet);

        break;

    default:

        /* invalid pid : frame interrupted */

        usb_packet_unmap(&async->packet, &async->sgl);

        uhci_async_free(async);

        s->status |= UHCI_STS_HCPERR;

        uhci_update_irq(s);

        return TD_RESULT_STOP_FRAME;

    }

    if (async->packet.status == USB_RET_ASYNC) {

        uhci_async_link(async);

        if (!queuing) {

            uhci_queue_fill(q, td);

        }

        return TD_RESULT_ASYNC_START;

    }