summaryrefslogtreecommitdiff
path: root/hw/usb/dev-storage.c
blob: c434c5680f905e11c149feb801bc6aea8eaec651 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
/*
 * USB Mass Storage Device emulation
 *
 * Copyright (c) 2006 CodeSourcery.
 * Written by Paul Brook
 *
 * This code is licensed under the LGPL.
 */

#include "qemu-common.h"
#include "qemu/option.h"
#include "qemu/config-file.h"
#include "hw/usb.h"
#include "hw/usb/desc.h"
#include "hw/scsi/scsi.h"
#include "ui/console.h"
#include "monitor/monitor.h"
#include "sysemu/sysemu.h"
#include "sysemu/blockdev.h"

//#define DEBUG_MSD

#ifdef DEBUG_MSD
#define DPRINTF(fmt, ...) \
do { printf("usb-msd: " fmt , ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) do {} while(0)
#endif

/* USB requests.  */
#define MassStorageReset  0xff
#define GetMaxLun         0xfe

enum USBMSDMode {
    USB_MSDM_CBW, /* Command Block.  */
    USB_MSDM_DATAOUT, /* Transfer data to device.  */
    USB_MSDM_DATAIN, /* Transfer data from device.  */
    USB_MSDM_CSW /* Command Status.  */
};

struct usb_msd_csw {
    uint32_t sig;
    uint32_t tag;
    uint32_t residue;
    uint8_t status;
};

typedef struct {
    USBDevice dev;
    enum USBMSDMode mode;
    uint32_t scsi_off;
    uint32_t scsi_len;
    uint32_t data_len;
    struct usb_msd_csw csw;
    SCSIRequest *req;
    SCSIBus bus;
    /* For async completion.  */
    USBPacket *packet;
    /* usb-storage only */
    BlockConf conf;
    uint32_t removable;
} MSDState;

struct usb_msd_cbw {
    uint32_t sig;
    uint32_t tag;
    uint32_t data_len;
    uint8_t flags;
    uint8_t lun;
    uint8_t cmd_len;
    uint8_t cmd[16];
};

enum {
    STR_MANUFACTURER = 1,
    STR_PRODUCT,
    STR_SERIALNUMBER,
    STR_CONFIG_FULL,
    STR_CONFIG_HIGH,
    STR_CONFIG_SUPER,
};

static const USBDescStrings desc_strings = {
    [STR_MANUFACTURER] = "QEMU",
    [STR_PRODUCT]      = "QEMU USB HARDDRIVE",
    [STR_SERIALNUMBER] = "1",
    [STR_CONFIG_FULL]  = "Full speed config (usb 1.1)",
    [STR_CONFIG_HIGH]  = "High speed config (usb 2.0)",
    [STR_CONFIG_SUPER] = "Super speed config (usb 3.0)",
};

static const USBDescIface desc_iface_full = {
    .bInterfaceNumber              = 0,
    .bNumEndpoints                 = 2,
    .bInterfaceClass               = USB_CLASS_MASS_STORAGE,
    .bInterfaceSubClass            = 0x06, /* SCSI */
    .bInterfaceProtocol            = 0x50, /* Bulk */
    .eps = (USBDescEndpoint[]) {
        {
            .bEndpointAddress      = USB_DIR_IN | 0x01,
            .bmAttributes          = USB_ENDPOINT_XFER_BULK,
            .wMaxPacketSize        = 64,
        },{
            .bEndpointAddress      = USB_DIR_OUT | 0x02,
            .bmAttributes          = USB_ENDPOINT_XFER_BULK,
            .wMaxPacketSize        = 64,
        },
    }
};

static const USBDescDevice desc_device_full = {
    .bcdUSB                        = 0x0200,
    .bMaxPacketSize0               = 8,
    .bNumConfigurations            = 1,
    .confs = (USBDescConfig[]) {
        {
            .bNumInterfaces        = 1,
            .bConfigurationValue   = 1,
            .iConfiguration        = STR_CONFIG_FULL,
            .bmAttributes          = 0xc0,
            .nif = 1,
            .ifs = &desc_iface_full,
        },
    },
};

static const USBDescIface desc_iface_high = {
    .bInterfaceNumber              = 0,
    .bNumEndpoints                 = 2,
    .bInterfaceClass               = USB_CLASS_MASS_STORAGE,
    .bInterfaceSubClass            = 0x06, /* SCSI */
    .bInterfaceProtocol            = 0x50, /* Bulk */
    .eps = (USBDescEndpoint[]) {
        {
            .bEndpointAddress      = USB_DIR_IN | 0x01,
            .bmAttributes          = USB_ENDPOINT_XFER_BULK,
            .wMaxPacketSize        = 512,
        },{
            .bEndpointAddress      = USB_DIR_OUT | 0x02,
            .bmAttributes          = USB_ENDPOINT_XFER_BULK,
            .wMaxPacketSize        = 512,
        },
    }
};

static const USBDescDevice desc_device_high = {
    .bcdUSB                        = 0x0200,
    .bMaxPacketSize0               = 64,
    .bNumConfigurations            = 1,
    .confs = (USBDescConfig[]) {
        {
            .bNumInterfaces        = 1,
            .bConfigurationValue   = 1,
            .iConfiguration        = STR_CONFIG_HIGH,
            .bmAttributes          = 0xc0,
            .nif = 1,
            .ifs = &desc_iface_high,
        },
    },
};

static const USBDescIface desc_iface_super = {
    .bInterfaceNumber              = 0,
    .bNumEndpoints                 = 2,
    .bInterfaceClass               = USB_CLASS_MASS_STORAGE,
    .bInterfaceSubClass            = 0x06, /* SCSI */
    .bInterfaceProtocol            = 0x50, /* Bulk */
    .eps = (USBDescEndpoint[]) {
        {
            .bEndpointAddress      = USB_DIR_IN | 0x01,
            .bmAttributes          = USB_ENDPOINT_XFER_BULK,
            .wMaxPacketSize        = 1024,
            .bMaxBurst             = 15,
        },{
            .bEndpointAddress      = USB_DIR_OUT | 0x02,
            .bmAttributes          = USB_ENDPOINT_XFER_BULK,
            .wMaxPacketSize        = 1024,
            .bMaxBurst             = 15,
        },
    }
};

static const USBDescDevice desc_device_super = {
    .bcdUSB                        = 0x0300,
    .bMaxPacketSize0               = 9,
    .bNumConfigurations            = 1,
    .confs = (USBDescConfig[]) {
        {
            .bNumInterfaces        = 1,
            .bConfigurationValue   = 1,
            .iConfiguration        = STR_CONFIG_SUPER,
            .bmAttributes          = 0xc0,
            .nif = 1,
            .ifs = &desc_iface_super,
        },
    },
};

static const USBDesc desc = {
    .id = {
        .idVendor          = 0x46f4, /* CRC16() of "QEMU" */
        .idProduct         = 0x0001,
        .bcdDevice         = 0,
        .iManufacturer     = STR_MANUFACTURER,
        .iProduct          = STR_PRODUCT,
        .iSerialNumber     = STR_SERIALNUMBER,
    },
    .full  = &desc_device_full,
    .high  = &desc_device_high,
    .super = &desc_device_super,
    .str   = desc_strings,
};

static void usb_msd_copy_data(MSDState *s, USBPacket *p)
{
    uint32_t len;
    len = p->iov.size - p->actual_length;
    if (len > s->scsi_len)
        len = s->scsi_len;
    usb_packet_copy(p, scsi_req_get_buf(s->req) + s->scsi_off, len);
    s->scsi_len -= len;
    s->scsi_off += len;
    s->data_len -= len;
    if (s->scsi_len == 0 || s->data_len == 0) {
        scsi_req_continue(s->req);
    }
}

static void usb_msd_send_status(MSDState *s, USBPacket *p)
{
    int len;

    DPRINTF("Command status %d tag 0x%x, len %zd\n",
            s->csw.status, le32_to_cpu(s->csw.tag), p->iov.size);

    assert(s->csw.sig == cpu_to_le32(0x53425355));
    len = MIN(sizeof(s->csw), p->iov.size);
    usb_packet_copy(p, &s->csw, len);
    memset(&s->csw, 0, sizeof(s->csw));
}

static void usb_msd_packet_complete(MSDState *s)
{
    USBPacket *p = s->packet;

    /* Set s->packet to NULL before calling usb_packet_complete
       because another request may be issued before
       usb_packet_complete returns.  */
    DPRINTF("Packet complete %p\n", p);
    s->packet = NULL;
    usb_packet_complete(&s->dev, p);
}

static void usb_msd_transfer_data(SCSIRequest *req, uint32_t len)
{
    MSDState *s = DO_UPCAST(MSDState, dev.qdev, req->bus->qbus.parent);
    USBPacket *p = s->packet;

    assert((s->mode == USB_MSDM_DATAOUT) == (req->cmd.mode == SCSI_XFER_TO_DEV));
    s->scsi_len = len;
    s->scsi_off = 0;
    if (p) {
        usb_msd_copy_data(s, p);
        p = s->packet;
        if (p && p->actual_length == p->iov.size) {
            p->status = USB_RET_SUCCESS; /* Clear previous ASYNC status */
            usb_msd_packet_complete(s);
        }
    }
}

static void usb_msd_command_complete(SCSIRequest *req, uint32_t status, size_t resid)
{
    MSDState *s = DO_UPCAST(MSDState, dev.qdev, req->bus->qbus.parent);
    USBPacket *p = s->packet;

    DPRINTF("Command complete %d tag 0x%x\n", status, req->tag);

    s->csw.sig = cpu_to_le32(0x53425355);
    s->csw.tag = cpu_to_le32(req->tag);
    s->csw.residue = cpu_to_le32(s->data_len);
    s->csw.status = status != 0;

    if (s->packet) {
        if (s->data_len == 0 && s->mode == USB_MSDM_DATAOUT) {
            /* A deferred packet with no write data remaining must be
               the status read packet.  */
            usb_msd_send_status(s, p);
            s->mode = USB_MSDM_CBW;
        } else if (s->mode == USB_MSDM_CSW) {
            usb_msd_send_status(s, p);
            s->mode = USB_MSDM_CBW;
        } else {
            if (s->data_len) {
                int len = (p->iov.size - p->actual_length);
                usb_packet_skip(p, len);
                s->data_len -= len;
            }
            if (s->data_len == 0) {
                s->mode = USB_MSDM_CSW;
            }
        }
        p->status = USB_RET_SUCCESS; /* Clear previous ASYNC status */
        usb_msd_packet_complete(s);
    } else if (s->data_len == 0) {
        s->mode = USB_MSDM_CSW;
    }
    scsi_req_unref(req);
    s->req = NULL;
}

static void usb_msd_request_cancelled(SCSIRequest *req)
{
    MSDState *s = DO_UPCAST(MSDState, dev.qdev, req->bus->qbus.parent);

    if (req == s->req) {
        scsi_req_unref(s->req);
        s->req = NULL;
        s->scsi_len = 0;
    }
}

static void usb_msd_handle_reset(USBDevice *dev)
{
    MSDState *s = (MSDState *)dev;

    DPRINTF("Reset\n");
    if (s->req) {
        scsi_req_cancel(s->req);
    }
    assert(s->req == NULL);

    if (s->packet) {
        s->packet->status = USB_RET_STALL;
        usb_msd_packet_complete(s);
    }

    s->mode = USB_MSDM_CBW;
}

static void usb_msd_handle_control(USBDevice *dev, USBPacket *p,
               int request, int value, int index, int length, uint8_t *data)
{
    MSDState *s = (MSDState *)dev;
    SCSIDevice *scsi_dev;
    int ret, maxlun;

    ret = usb_desc_handle_control(dev, p, request, value, index, length, data);
    if (ret >= 0) {
        return;
    }

    switch (request) {
    case EndpointOutRequest | USB_REQ_CLEAR_FEATURE:
        break;
        /* Class specific requests.  */
    case ClassInterfaceOutRequest | MassStorageReset:
        /* Reset state ready for the next CBW.  */
        s->mode = USB_MSDM_CBW;
        break;
    case ClassInterfaceRequest | GetMaxLun:
        maxlun = 0;
        for (;;) {
            scsi_dev = scsi_device_find(&s->bus, 0, 0, maxlun+1);
            if (scsi_dev == NULL) {
                break;
            }
            if (scsi_dev->lun != maxlun+1) {
                break;
            }
            maxlun++;
        }
        DPRINTF("MaxLun %d\n", maxlun);
        data[0] = maxlun;
        p->actual_length = 1;
        break;
    default:
        p->status = USB_RET_STALL;
        break;
    }
}

static void usb_msd_cancel_io(USBDevice *dev, USBPacket *p)
{
    MSDState *s = DO_UPCAST(MSDState, dev, dev);

    assert(s->packet == p);
    s->packet = NULL;

    if (s->req) {
        scsi_req_cancel(s->req);
    }
}

static void usb_msd_handle_data(USBDevice *dev, USBPacket *p)
{
    MSDState *s = (MSDState *)dev;
    uint32_t tag;
    struct usb_msd_cbw cbw;
    uint8_t devep = p->ep->nr;
    SCSIDevice *scsi_dev;
    uint32_t len;

    switch (p->pid) {
    case USB_TOKEN_OUT:
        if (devep != 2)
            goto fail;

        switch (s->mode) {
        case USB_MSDM_CBW:
            if (p->iov.size != 31) {
                fprintf(stderr, "usb-msd: Bad CBW size");
                goto fail;
            }
            usb_packet_copy(p, &cbw, 31);
            if (le32_to_cpu(cbw.sig) != 0x43425355) {
                fprintf(stderr, "usb-msd: Bad signature %08x\n",
                        le32_to_cpu(cbw.sig));
                goto fail;
            }
            DPRINTF("Command on LUN %d\n", cbw.lun);
            scsi_dev = scsi_device_find(&s->bus, 0, 0, cbw.lun);
            if (scsi_dev == NULL) {
                fprintf(stderr, "usb-msd: Bad LUN %d\n", cbw.lun);
                goto fail;
            }
            tag = le32_to_cpu(cbw.tag);
            s->data_len = le32_to_cpu(cbw.data_len);
            if (s->data_len == 0) {
                s->mode = USB_MSDM_CSW;
            } else if (cbw.flags & 0x80) {
                s->mode = USB_MSDM_DATAIN;
            } else {
                s->mode = USB_MSDM_DATAOUT;
            }
            DPRINTF("Command tag 0x%x flags %08x len %d data %d\n",
                    tag, cbw.flags, cbw.cmd_len, s->data_len);
            assert(le32_to_cpu(s->csw.residue) == 0);
            s->scsi_len = 0;
            s->req = scsi_req_new(scsi_dev, tag, cbw.lun, cbw.cmd, NULL);
#ifdef DEBUG_MSD
            scsi_req_print(s->req);
#endif
            len = scsi_req_enqueue(s->req);
            if (len) {
                scsi_req_continue(s->req);
            }
            break;

        case USB_MSDM_DATAOUT:
            DPRINTF("Data out %zd/%d\n", p->iov.size, s->data_len);
            if (p->iov.size > s->data_len) {
                goto fail;
            }

            if (s->scsi_len) {
                usb_msd_copy_data(s, p);
            }
            if (le32_to_cpu(s->csw.residue)) {
                int len = p->iov.size - p->actual_length;
                if (len) {
                    usb_packet_skip(p, len);
                    s->data_len -= len;
                    if (s->data_len == 0) {
                        s->mode = USB_MSDM_CSW;
                    }
                }
            }
            if (p->actual_length < p->iov.size) {
                DPRINTF("Deferring packet %p [wait data-out]\n", p);
                s->packet = p;
                p->status = USB_RET_ASYNC;
            }
            break;

        default:
            DPRINTF("Unexpected write (len %zd)\n", p->iov.size);
            goto fail;
        }
        break;

    case USB_TOKEN_IN:
        if (devep != 1)
            goto fail;

        switch (s->mode) {
        case USB_MSDM_DATAOUT:
            if (s->data_len != 0 || p->iov.size < 13) {
                goto fail;
            }
            /* Waiting for SCSI write to complete.  */
            s->packet = p;
            p->status = USB_RET_ASYNC;
            break;

        case USB_MSDM_CSW:
            if (p->iov.size < 13) {
                goto fail;
            }

            if (s->req) {
                /* still in flight */
                DPRINTF("Deferring packet %p [wait status]\n", p);
                s->packet = p;
                p->status = USB_RET_ASYNC;
            } else {
                usb_msd_send_status(s, p);
                s->mode = USB_MSDM_CBW;
            }
            break;

        case USB_MSDM_DATAIN:
            DPRINTF("Data in %zd/%d, scsi_len %d\n",
                    p->iov.size, s->data_len, s->scsi_len);
            if (s->scsi_len) {
                usb_msd_copy_data(s, p);
            }
            if (le32_to_cpu(s->csw.residue)) {
                int len = p->iov.size - p->actual_length;
                if (len) {
                    usb_packet_skip(p, len);
                    s->data_len -= len;
                    if (s->data_len == 0) {
                        s->mode = USB_MSDM_CSW;
                    }
                }
            }
            if (p->actual_length < p->iov.size) {
                DPRINTF("Deferring packet %p [wait data-in]\n", p);
                s->packet = p;
                p->status = USB_RET_ASYNC;
            }
            break;

        default:
            DPRINTF("Unexpected read (len %zd)\n", p->iov.size);
            goto fail;
        }
        break;

    default:
        DPRINTF("Bad token\n");
    fail:
        p->status = USB_RET_STALL;
        break;
    }
}

static void usb_msd_password_cb(void *opaque, int err)
{
    MSDState *s = opaque;

    if (!err)
        err = usb_device_attach(&s->dev);

    if (err)
        qdev_unplug(&s->dev.qdev, NULL);
}

static void *usb_msd_load_request(QEMUFile *f, SCSIRequest *req)
{
    MSDState *s = DO_UPCAST(MSDState, dev.qdev, req->bus->qbus.parent);

    /* nothing to load, just store req in our state struct */
    assert(s->req == NULL);
    scsi_req_ref(req);
    s->req = req;
    return NULL;
}

static const struct SCSIBusInfo usb_msd_scsi_info_storage = {
    .tcq = false,
    .max_target = 0,
    .max_lun = 0,

    .transfer_data = usb_msd_transfer_data,
    .complete = usb_msd_command_complete,
    .cancel = usb_msd_request_cancelled,
    .load_request = usb_msd_load_request,
};

static const struct SCSIBusInfo usb_msd_scsi_info_bot = {
    .tcq = false,
    .max_target = 0,
    .max_lun = 15,

    .transfer_data = usb_msd_transfer_data,
    .complete = usb_msd_command_complete,
    .cancel = usb_msd_request_cancelled,
    .load_request = usb_msd_load_request,
};

static int usb_msd_initfn_storage(USBDevice *dev)
{
    MSDState *s = DO_UPCAST(MSDState, dev, dev);
    BlockDriverState *bs = s->conf.bs;
    SCSIDevice *scsi_dev;
    Error *err = NULL;

    if (!bs) {
        error_report("drive property not set");
        return -1;
    }

    blkconf_serial(&s->conf, &dev->serial);

    /*
     * Hack alert: this pretends to be a block device, but it's really
     * a SCSI bus that can serve only a single device, which it
     * creates automatically.  But first it needs to detach from its
     * blockdev, or else scsi_bus_legacy_add_drive() dies when it
     * attaches again.
     *
     * The hack is probably a bad idea.
     */
    bdrv_detach_dev(bs, &s->dev.qdev);
    s->conf.bs = NULL;

    usb_desc_create_serial(dev);
    usb_desc_init(dev);
    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(dev),
                 &usb_msd_scsi_info_storage, NULL);
    scsi_dev = scsi_bus_legacy_add_drive(&s->bus, bs, 0, !!s->removable,
                                         s->conf.bootindex, dev->serial,
                                         &err);
    if (!scsi_dev) {
        return -1;
    }
    s->bus.qbus.allow_hotplug = 0;
    usb_msd_handle_reset(dev);

    if (bdrv_key_required(bs)) {
        if (cur_mon) {
            monitor_read_bdrv_key_start(cur_mon, bs, usb_msd_password_cb, s);
            s->dev.auto_attach = 0;
        } else {
            autostart = 0;
        }
    }

    return 0;
}

static int usb_msd_initfn_bot(USBDevice *dev)
{
    MSDState *s = DO_UPCAST(MSDState, dev, dev);

    usb_desc_create_serial(dev);
    usb_desc_init(dev);
    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(dev),
                 &usb_msd_scsi_info_bot, NULL);
    s->bus.qbus.allow_hotplug = 0;
    usb_msd_handle_reset(dev);

    return 0;
}

static USBDevice *usb_msd_init(USBBus *bus, const char *filename)
{
    static int nr=0;
    char id[8];
    QemuOpts *opts;
    DriveInfo *dinfo;
    USBDevice *dev;
    const char *p1;
    char fmt[32];

    /* parse -usbdevice disk: syntax into drive opts */
    snprintf(id, sizeof(id), "usb%d", nr++);
    opts = qemu_opts_create(qemu_find_opts("drive"), id, 0, NULL);

    p1 = strchr(filename, ':');
    if (p1++) {
        const char *p2;

        if (strstart(filename, "format=", &p2)) {
            int len = MIN(p1 - p2, sizeof(fmt));
            pstrcpy(fmt, len, p2);
            qemu_opt_set(opts, "format", fmt);
        } else if (*filename != ':') {
            printf("unrecognized USB mass-storage option %s\n", filename);
            return NULL;
        }
        filename = p1;
    }
    if (!*filename) {
        printf("block device specification needed\n");
        return NULL;
    }
    qemu_opt_set(opts, "file", filename);
    qemu_opt_set(opts, "if", "none");

    /* create host drive */
    dinfo = drive_init(opts, 0);
    if (!dinfo) {
        qemu_opts_del(opts);
        return NULL;
    }

    /* create guest device */
    dev = usb_create(bus, "usb-storage");
    if (!dev) {
        return NULL;
    }
    if (qdev_prop_set_drive(&dev->qdev, "drive", dinfo->bdrv) < 0) {
        object_unparent(OBJECT(dev));
        return NULL;
    }
    if (qdev_init(&dev->qdev) < 0)
        return NULL;

    return dev;
}

static const VMStateDescription vmstate_usb_msd = {
    .name = "usb-storage",
    .version_id = 1,
    .minimum_version_id = 1,
    .fields = (VMStateField []) {
        VMSTATE_USB_DEVICE(dev, MSDState),
        VMSTATE_UINT32(mode, MSDState),
        VMSTATE_UINT32(scsi_len, MSDState),
        VMSTATE_UINT32(scsi_off, MSDState),
        VMSTATE_UINT32(data_len, MSDState),
        VMSTATE_UINT32(csw.sig, MSDState),
        VMSTATE_UINT32(csw.tag, MSDState),
        VMSTATE_UINT32(csw.residue, MSDState),
        VMSTATE_UINT8(csw.status, MSDState),
        VMSTATE_END_OF_LIST()
    }
};

static Property msd_properties[] = {
    DEFINE_BLOCK_PROPERTIES(MSDState, conf),
    DEFINE_PROP_BIT("removable", MSDState, removable, 0, false),
    DEFINE_PROP_END_OF_LIST(),
};

static void usb_msd_class_initfn_common(ObjectClass *klass)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    USBDeviceClass *uc = USB_DEVICE_CLASS(klass);

    uc->product_desc   = "QEMU USB MSD";
    uc->usb_desc       = &desc;
    uc->cancel_packet  = usb_msd_cancel_io;
    uc->handle_attach  = usb_desc_attach;
    uc->handle_reset   = usb_msd_handle_reset;
    uc->handle_control = usb_msd_handle_control;
    uc->handle_data    = usb_msd_handle_data;
    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
    dc->fw_name = "storage";
    dc->vmsd = &vmstate_usb_msd;
}

static void usb_msd_class_initfn_storage(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    USBDeviceClass *uc = USB_DEVICE_CLASS(klass);

    uc->init = usb_msd_initfn_storage;
    dc->props = msd_properties;
    usb_msd_class_initfn_common(klass);
}

static void usb_msd_class_initfn_bot(ObjectClass *klass, void *data)
{
    USBDeviceClass *uc = USB_DEVICE_CLASS(klass);

    uc->init = usb_msd_initfn_bot;
    usb_msd_class_initfn_common(klass);
}

static const TypeInfo msd_info = {
    .name          = "usb-storage",
    .parent        = TYPE_USB_DEVICE,
    .instance_size = sizeof(MSDState),
    .class_init    = usb_msd_class_initfn_storage,
};

static const TypeInfo bot_info = {
    .name          = "usb-bot",
    .parent        = TYPE_USB_DEVICE,
    .instance_size = sizeof(MSDState),
    .class_init    = usb_msd_class_initfn_bot,
};

static void usb_msd_register_types(void)
{
    type_register_static(&msd_info);
    type_register_static(&bot_info);
    usb_legacy_register("usb-storage", "disk", usb_msd_init);
}

type_init(usb_msd_register_types)