drivers/block/ub.c

   1 /*
   2  * The low performance USB storage driver (ub).
   3  *
   4  * Copyright (c) 1999, 2000 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
   5  * Copyright (C) 2004 Pete Zaitcev (zaitcev@yahoo.com)
   6  *
   7  * This work is a part of Linux kernel, is derived from it,
   8  * and is not licensed separately. See file COPYING for details.
   9  *
  10  * TODO (sorted by decreasing priority)
  11  *  -- Return sense now that rq allows it (we always auto-sense anyway).
  12  *  -- set readonly flag for CDs, set removable flag for CF readers
  13  *  -- do inquiry and verify we got a disk and not a tape (for LUN mismatch)
  14  *  -- verify the 13 conditions and do bulk resets
  15  *  -- highmem
  16  *  -- move top_sense and work_bcs into separate allocations (if they survive)
  17  *     for cache purists and esoteric architectures.
  18  *  -- Allocate structure for LUN 0 before the first ub_sync_tur, avoid NULL. ?
  19  *  -- prune comments, they are too volumnous
  20  *  -- Resove XXX's
  21  *  -- CLEAR, CLR2STS, CLRRS seem to be ripe for refactoring.
  22  */
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/usb.h>
  26 #include <linux/usb_usual.h>
  27 #include <linux/blkdev.h>
  28 #include <linux/timer.h>
  29 #include <linux/scatterlist.h>
  30 #include <scsi/scsi.h>
  31
  32 #define DRV_NAME "ub"
  33
  34 #define UB_MAJOR 180
  35
  36 /*
  37  * The command state machine is the key model for understanding of this driver.
  38  *
  39  * The general rule is that all transitions are done towards the bottom
  40  * of the diagram, thus preventing any loops.
  41  *
  42  * An exception to that is how the STAT state is handled. A counter allows it
  43  * to be re-entered along the path marked with [C].
  44  *
  45  *       +--------+
  46  *       ! INIT   !
  47  *       +--------+
  48  *           !
  49  *        ub_scsi_cmd_start fails ->--------------------------------------\
  50  *           !                                                            !
  51  *           V                                                            !
  52  *       +--------+                                                       !
  53  *       ! CMD    !                                                       !
  54  *       +--------+                                                       !
  55  *           !                                            +--------+      !
  56  *         was -EPIPE -->-------------------------------->! CLEAR  !      !
  57  *           !                                            +--------+      !
  58  *           !                                                !           !
  59  *         was error -->------------------------------------- ! --------->\
  60  *           !                                                !           !
  61  *  /--<-- cmd->dir == NONE ?                                 !           !
  62  *  !        !                                                !           !
  63  *  !        V                                                !           !
  64  *  !    +--------+                                           !           !
  65  *  !    ! DATA   !                                           !           !
  66  *  !    +--------+                                           !           !
  67  *  !        !                           +---------+          !           !
  68  *  !      was -EPIPE -->--------------->! CLR2STS !          !           !
  69  *  !        !                           +---------+          !           !
  70  *  !        !                                !               !           !
  71  *  !        !                              was error -->---- ! --------->\
  72  *  !      was error -->--------------------- ! ------------- ! --------->\
  73  *  !        !                                !               !           !
  74  *  !        V                                !               !           !
  75  *  \--->+--------+                           !               !           !
  76  *       ! STAT   !<--------------------------/               !           !
  77  *  /--->+--------+                                           !           !
  78  *  !        !                                                !           !
  79  * [C]     was -EPIPE -->-----------\                         !           !
  80  *  !        !                      !                         !           !
  81  *  +<---- len == 0                 !                         !           !
  82  *  !        !                      !                         !           !
  83  *  !      was error -->--------------------------------------!---------->\
  84  *  !        !                      !                         !           !
  85  *  +<---- bad CSW                  !                         !           !
  86  *  +<---- bad tag                  !                         !           !
  87  *  !        !                      V                         !           !
  88  *  !        !                 +--------+                     !           !
  89  *  !        !                 ! CLRRS  !                     !           !
  90  *  !        !                 +--------+                     !           !
  91  *  !        !                      !                         !           !
  92  *  \------- ! --------------------[C]--------\               !           !
  93  *           !                                !               !           !
  94  *         cmd->error---\                +--------+           !           !
  95  *           !          +--------------->! SENSE  !<----------/           !
  96  *         STAT_FAIL----/                +--------+                       !
  97  *           !                                !                           V
  98  *           !                                V                      +--------+
  99  *           \--------------------------------\--------------------->! DONE   !
 100  *                                                                   +--------+
 101  */
 102
 103 /*
 104  * This many LUNs per USB device.
 105  * Every one of them takes a host, see UB_MAX_HOSTS.
 106  */
 107 #define UB_MAX_LUNS   9
 108
 109 /*
 110  */
 111
 112 #define UB_PARTS_PER_LUN      8
 113
 114 #define UB_MAX_CDB_SIZE      16         /* Corresponds to Bulk */
 115
 116 #define UB_SENSE_SIZE  18
 117
 118 /*
 119  */
 120
 121 /* command block wrapper */
 122 struct bulk_cb_wrap {
 123         __le32  Signature;              /* contains 'USBC' */
 124         u32     Tag;                    /* unique per command id */
 125         __le32  DataTransferLength;     /* size of data */
 126         u8      Flags;                  /* direction in bit 0 */
 127         u8      Lun;                    /* LUN */
 128         u8      Length;                 /* of of the CDB */
 129         u8      CDB[UB_MAX_CDB_SIZE];   /* max command */
 130 };
 131
 132 #define US_BULK_CB_WRAP_LEN     31
 133 #define US_BULK_CB_SIGN         0x43425355      /*spells out USBC */
 134 #define US_BULK_FLAG_IN         1
 135 #define US_BULK_FLAG_OUT        0
 136
 137 /* command status wrapper */
 138 struct bulk_cs_wrap {
 139         __le32  Signature;              /* should = 'USBS' */
 140         u32     Tag;                    /* same as original command */
 141         __le32  Residue;                /* amount not transferred */
 142         u8      Status;                 /* see below */
 143 };
 144
 145 #define US_BULK_CS_WRAP_LEN     13
 146 #define US_BULK_CS_SIGN         0x53425355      /* spells out 'USBS' */
 147 #define US_BULK_STAT_OK         0
 148 #define US_BULK_STAT_FAIL       1
 149 #define US_BULK_STAT_PHASE      2
 150
 151 /* bulk-only class specific requests */
 152 #define US_BULK_RESET_REQUEST   0xff
 153 #define US_BULK_GET_MAX_LUN     0xfe
 154
 155 /*
 156  */
 157 struct ub_dev;
 158
 159 #define UB_MAX_REQ_SG   9       /* cdrecord requires 32KB and maybe a header */
 160 #define UB_MAX_SECTORS 64
 161
 162 /*
 163  * A second is more than enough for a 32K transfer (UB_MAX_SECTORS)
 164  * even if a webcam hogs the bus, but some devices need time to spin up.
 165  */
 166 #define UB_URB_TIMEOUT  (HZ*2)
 167 #define UB_DATA_TIMEOUT (HZ*5)  /* ZIP does spin-ups in the data phase */
 168 #define UB_STAT_TIMEOUT (HZ*5)  /* Same spinups and eject for a dataless cmd. */
 169 #define UB_CTRL_TIMEOUT (HZ/2)  /* 500ms ought to be enough to clear a stall */
 170
 171 /*
 172  * An instance of a SCSI command in transit.
 173  */
 174 #define UB_DIR_NONE     0
 175 #define UB_DIR_READ     1
 176 #define UB_DIR_ILLEGAL2 2
 177 #define UB_DIR_WRITE    3
 178
 179 #define UB_DIR_CHAR(c)  (((c)==UB_DIR_WRITE)? 'w': \
 180                          (((c)==UB_DIR_READ)? 'r': 'n'))
 181
 182 enum ub_scsi_cmd_state {
 183         UB_CMDST_INIT,                  /* Initial state */
 184         UB_CMDST_CMD,                   /* Command submitted */
 185         UB_CMDST_DATA,                  /* Data phase */
 186         UB_CMDST_CLR2STS,               /* Clearing before requesting status */
 187         UB_CMDST_STAT,                  /* Status phase */
 188         UB_CMDST_CLEAR,                 /* Clearing a stall (halt, actually) */
 189         UB_CMDST_CLRRS,                 /* Clearing before retrying status */
 190         UB_CMDST_SENSE,                 /* Sending Request Sense */
 191         UB_CMDST_DONE                   /* Final state */
 192 };
 193
 194 struct ub_scsi_cmd {
 195         unsigned char cdb[UB_MAX_CDB_SIZE];
 196         unsigned char cdb_len;
 197
 198         unsigned char dir;              /* 0 - none, 1 - read, 3 - write. */
 199         enum ub_scsi_cmd_state state;
 200         unsigned int tag;
 201         struct ub_scsi_cmd *next;
 202
 203         int error;                      /* Return code - valid upon done */
 204         unsigned int act_len;           /* Return size */
 205         unsigned char key, asc, ascq;   /* May be valid if error==-EIO */
 206
 207         int stat_count;                 /* Retries getting status. */
 208         unsigned int timeo;             /* jiffies until rq->timeout changes */
 209
 210         unsigned int len;               /* Requested length */
 211         unsigned int current_sg;
 212         unsigned int nsg;               /* sgv[nsg] */
 213         struct scatterlist sgv[UB_MAX_REQ_SG];
 214
 215         struct ub_lun *lun;
 216         void (*done)(struct ub_dev *, struct ub_scsi_cmd *);
 217         void *back;
 218 };
 219
 220 struct ub_request {
 221         struct request *rq;
 222         unsigned int current_try;
 223         unsigned int nsg;               /* sgv[nsg] */
 224         struct scatterlist sgv[UB_MAX_REQ_SG];
 225 };
 226
 227 /*
 228  */
 229 struct ub_capacity {
 230         unsigned long nsec;             /* Linux size - 512 byte sectors */
 231         unsigned int bsize;             /* Linux hardsect_size */
 232         unsigned int bshift;            /* Shift between 512 and hard sects */
 233 };
 234
 235 /*
 236  * This is a direct take-off from linux/include/completion.h
 237  * The difference is that I do not wait on this thing, just poll.
 238  * When I want to wait (ub_probe), I just use the stock completion.
 239  *
 240  * Note that INIT_COMPLETION takes no lock. It is correct. But why
 241  * in the bloody hell that thing takes struct instead of pointer to struct
 242  * is quite beyond me. I just copied it from the stock completion.
 243  */
 244 struct ub_completion {
 245         unsigned int done;
 246         spinlock_t lock;
 247 };
 248
 249 static inline void ub_init_completion(struct ub_completion *x)
 250 {
 251         x->done = 0;
 252         spin_lock_init(&x->lock);
 253 }
 254
 255 #define UB_INIT_COMPLETION(x)   ((x).done = 0)
 256
 257 static void ub_complete(struct ub_completion *x)
 258 {
 259         unsigned long flags;
 260
 261         spin_lock_irqsave(&x->lock, flags);
 262         x->done++;
 263         spin_unlock_irqrestore(&x->lock, flags);
 264 }
 265
 266 static int ub_is_completed(struct ub_completion *x)
 267 {
 268         unsigned long flags;
 269         int ret;
 270
 271         spin_lock_irqsave(&x->lock, flags);
 272         ret = x->done;
 273         spin_unlock_irqrestore(&x->lock, flags);
 274         return ret;
 275 }
 276
 277 /*
 278  */
 279 struct ub_scsi_cmd_queue {
 280         int qlen, qmax;
 281         struct ub_scsi_cmd *head, *tail;
 282 };
 283
 284 /*
 285  * The block device instance (one per LUN).
 286  */
 287 struct ub_lun {
 288         struct ub_dev *udev;
 289         struct list_head link;
 290         struct gendisk *disk;
 291         int id;                         /* Host index */
 292         int num;                        /* LUN number */
 293         char name[16];
 294
 295         int changed;                    /* Media was changed */
 296         int removable;
 297         int readonly;
 298
 299         struct ub_request urq;
 300
 301         /* Use Ingo's mempool if or when we have more than one command. */
 302         /*
 303          * Currently we never need more than one command for the whole device.
 304          * However, giving every LUN a command is a cheap and automatic way
 305          * to enforce fairness between them.
 306          */
 307         int cmda[1];
 308         struct ub_scsi_cmd cmdv[1];
 309
 310         struct ub_capacity capacity;
 311 };
 312
 313 /*
 314  * The USB device instance.
 315  */
 316 struct ub_dev {
 317         spinlock_t *lock;
 318         atomic_t poison;                /* The USB device is disconnected */
 319         int openc;                      /* protected by ub_lock! */
 320                                         /* kref is too implicit for our taste */
 321         int reset;                      /* Reset is running */
 322         int bad_resid;
 323         unsigned int tagcnt;
 324         char name[12];
 325         struct usb_device *dev;
 326         struct usb_interface *intf;
 327
 328         struct list_head luns;
 329
 330         unsigned int send_bulk_pipe;    /* cached pipe values */
 331         unsigned int recv_bulk_pipe;
 332         unsigned int send_ctrl_pipe;
 333         unsigned int recv_ctrl_pipe;
 334
 335         struct tasklet_struct tasklet;
 336
 337         struct ub_scsi_cmd_queue cmd_queue;
 338         struct ub_scsi_cmd top_rqs_cmd; /* REQUEST SENSE */
 339         unsigned char top_sense[UB_SENSE_SIZE];
 340
 341         struct ub_completion work_done;
 342         struct urb work_urb;
 343         struct timer_list work_timer;
 344         int last_pipe;                  /* What might need clearing */
 345         __le32 signature;               /* Learned signature */
 346         struct bulk_cb_wrap work_bcb;
 347         struct bulk_cs_wrap work_bcs;
 348         struct usb_ctrlrequest work_cr;
 349
 350         struct work_struct reset_work;
 351         wait_queue_head_t reset_wait;
 352 };
 353
 354 /*
 355  */
 356 static void ub_cleanup(struct ub_dev *sc);
 357 static int ub_request_fn_1(struct ub_lun *lun, struct request *rq);
 358 static void ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
 359     struct ub_scsi_cmd *cmd, struct ub_request *urq);
 360 static void ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
 361     struct ub_scsi_cmd *cmd, struct ub_request *urq);
 362 static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 363 static void ub_end_rq(struct request *rq, unsigned int status);
 364 static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
 365     struct ub_request *urq, struct ub_scsi_cmd *cmd);
 366 static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 367 static void ub_urb_complete(struct urb *urb);
 368 static void ub_scsi_action(unsigned long _dev);
 369 static void ub_scsi_dispatch(struct ub_dev *sc);
 370 static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 371 static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 372 static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc);
 373 static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 374 static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 375 static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 376 static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 377 static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
 378     int stalled_pipe);
 379 static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd);
 380 static void ub_reset_enter(struct ub_dev *sc, int try);
 381 static void ub_reset_task(struct work_struct *work);
 382 static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun);
 383 static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
 384     struct ub_capacity *ret);
 385 static int ub_sync_reset(struct ub_dev *sc);
 386 static int ub_probe_clear_stall(struct ub_dev *sc, int stalled_pipe);
 387 static int ub_probe_lun(struct ub_dev *sc, int lnum);
 388
 389 /*
 390  */
 391 #ifdef CONFIG_USB_LIBUSUAL
 392
 393 #define ub_usb_ids  usb_storage_usb_ids
 394 #else
 395
 396 static struct usb_device_id ub_usb_ids[] = {
 397         { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, US_SC_SCSI, US_PR_BULK) },
 398         { }
 399 };
 400
 401 MODULE_DEVICE_TABLE(usb, ub_usb_ids);
 402 #endif /* CONFIG_USB_LIBUSUAL */
 403
 404 /*
 405  * Find me a way to identify "next free minor" for add_disk(),
 406  * and the array disappears the next day. However, the number of
 407  * hosts has something to do with the naming and /proc/partitions.
 408  * This has to be thought out in detail before changing.
 409  * If UB_MAX_HOST was 1000, we'd use a bitmap. Or a better data structure.
 410  */
 411 #define UB_MAX_HOSTS  26
 412 static char ub_hostv[UB_MAX_HOSTS];
 413
 414 #define UB_QLOCK_NUM 5
 415 static spinlock_t ub_qlockv[UB_QLOCK_NUM];
 416 static int ub_qlock_next = 0;
 417
 418 static DEFINE_SPINLOCK(ub_lock);        /* Locks globals and ->openc */
 419
 420 /*
 421  * The id allocator.
 422  *
 423  * This also stores the host for indexing by minor, which is somewhat dirty.
 424  */
 425 static int ub_id_get(void)
 426 {
 427         unsigned long flags;
 428         int i;
 429
 430         spin_lock_irqsave(&ub_lock, flags);
 431         for (i = 0; i < UB_MAX_HOSTS; i++) {
 432                 if (ub_hostv[i] == 0) {
 433                         ub_hostv[i] = 1;
 434                         spin_unlock_irqrestore(&ub_lock, flags);
 435                         return i;
 436                 }
 437         }
 438         spin_unlock_irqrestore(&ub_lock, flags);
 439         return -1;
 440 }
 441
 442 static void ub_id_put(int id)
 443 {
 444         unsigned long flags;
 445
 446         if (id < 0 || id >= UB_MAX_HOSTS) {
 447                 printk(KERN_ERR DRV_NAME ": bad host ID %d\n", id);
 448                 return;
 449         }
 450
 451         spin_lock_irqsave(&ub_lock, flags);
 452         if (ub_hostv[id] == 0) {
 453                 spin_unlock_irqrestore(&ub_lock, flags);
 454                 printk(KERN_ERR DRV_NAME ": freeing free host ID %d\n", id);
 455                 return;
 456         }
 457         ub_hostv[id] = 0;
 458         spin_unlock_irqrestore(&ub_lock, flags);
 459 }
 460
 461 /*
 462  * This is necessitated by the fact that blk_cleanup_queue does not
 463  * necesserily destroy the queue. Instead, it may merely decrease q->refcnt.
 464  * Since our blk_init_queue() passes a spinlock common with ub_dev,
 465  * we have life time issues when ub_cleanup frees ub_dev.
 466  */
 467 static spinlock_t *ub_next_lock(void)
 468 {
 469         unsigned long flags;
 470         spinlock_t *ret;
 471
 472         spin_lock_irqsave(&ub_lock, flags);
 473         ret = &ub_qlockv[ub_qlock_next];
 474         ub_qlock_next = (ub_qlock_next + 1) % UB_QLOCK_NUM;
 475         spin_unlock_irqrestore(&ub_lock, flags);
 476         return ret;
 477 }
 478
 479 /*
 480  * Downcount for deallocation. This rides on two assumptions:
 481  *  - once something is poisoned, its refcount cannot grow
 482  *  - opens cannot happen at this time (del_gendisk was done)
 483  * If the above is true, we can drop the lock, which we need for
 484  * blk_cleanup_queue(): the silly thing may attempt to sleep.
 485  * [Actually, it never needs to sleep for us, but it calls might_sleep()]
 486  */
 487 static void ub_put(struct ub_dev *sc)
 488 {
 489         unsigned long flags;
 490
 491         spin_lock_irqsave(&ub_lock, flags);
 492         --sc->openc;
 493         if (sc->openc == 0 && atomic_read(&sc->poison)) {
 494                 spin_unlock_irqrestore(&ub_lock, flags);
 495                 ub_cleanup(sc);
 496         } else {
 497                 spin_unlock_irqrestore(&ub_lock, flags);
 498         }
 499 }
 500
 501 /*
 502  * Final cleanup and deallocation.
 503  */
 504 static void ub_cleanup(struct ub_dev *sc)
 505 {
 506         struct list_head *p;
 507         struct ub_lun *lun;
 508         struct request_queue *q;
 509
 510         while (!list_empty(&sc->luns)) {
 511                 p = sc->luns.next;
 512                 lun = list_entry(p, struct ub_lun, link);
 513                 list_del(p);
 514
 515                 /* I don't think queue can be NULL. But... Stolen from sx8.c */
 516                 if ((q = lun->disk->queue) != NULL)
 517                         blk_cleanup_queue(q);
 518                 /*
 519                  * If we zero disk->private_data BEFORE put_disk, we have
 520                  * to check for NULL all over the place in open, release,
 521                  * check_media and revalidate, because the block level
 522                  * semaphore is well inside the put_disk.
 523                  * But we cannot zero after the call, because *disk is gone.
 524                  * The sd.c is blatantly racy in this area.
 525                  */
 526                 /* disk->private_data = NULL; */
 527                 put_disk(lun->disk);
 528                 lun->disk = NULL;
 529
 530                 ub_id_put(lun->id);
 531                 kfree(lun);
 532         }
 533
 534         usb_set_intfdata(sc->intf, NULL);
 535         usb_put_intf(sc->intf);
 536         usb_put_dev(sc->dev);
 537         kfree(sc);
 538 }
 539
 540 /*
 541  * The "command allocator".
 542  */
 543 static struct ub_scsi_cmd *ub_get_cmd(struct ub_lun *lun)
 544 {
 545         struct ub_scsi_cmd *ret;
 546
 547         if (lun->cmda[0])
 548                 return NULL;
 549         ret = &lun->cmdv[0];
 550         lun->cmda[0] = 1;
 551         return ret;
 552 }
 553
 554 static void ub_put_cmd(struct ub_lun *lun, struct ub_scsi_cmd *cmd)
 555 {
 556         if (cmd != &lun->cmdv[0]) {
 557                 printk(KERN_WARNING "%s: releasing a foreign cmd %p\n",
 558                     lun->name, cmd);
 559                 return;
 560         }
 561         if (!lun->cmda[0]) {
 562                 printk(KERN_WARNING "%s: releasing a free cmd\n", lun->name);
 563                 return;
 564         }
 565         lun->cmda[0] = 0;
 566 }
 567
 568 /*
 569  * The command queue.
 570  */
 571 static void ub_cmdq_add(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 572 {
 573         struct ub_scsi_cmd_queue *t = &sc->cmd_queue;
 574
 575         if (t->qlen++ == 0) {
 576                 t->head = cmd;
 577                 t->tail = cmd;
 578         } else {
 579                 t->tail->next = cmd;
 580                 t->tail = cmd;
 581         }
 582
 583         if (t->qlen > t->qmax)
 584                 t->qmax = t->qlen;
 585 }
 586
 587 static void ub_cmdq_insert(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 588 {
 589         struct ub_scsi_cmd_queue *t = &sc->cmd_queue;
 590
 591         if (t->qlen++ == 0) {
 592                 t->head = cmd;
 593                 t->tail = cmd;
 594         } else {
 595                 cmd->next = t->head;
 596                 t->head = cmd;
 597         }
 598
 599         if (t->qlen > t->qmax)
 600                 t->qmax = t->qlen;
 601 }
 602
 603 static struct ub_scsi_cmd *ub_cmdq_pop(struct ub_dev *sc)
 604 {
 605         struct ub_scsi_cmd_queue *t = &sc->cmd_queue;
 606         struct ub_scsi_cmd *cmd;
 607
 608         if (t->qlen == 0)
 609                 return NULL;
 610         if (--t->qlen == 0)
 611                 t->tail = NULL;
 612         cmd = t->head;
 613         t->head = cmd->next;
 614         cmd->next = NULL;
 615         return cmd;
 616 }
 617
 618 #define ub_cmdq_peek(sc)  ((sc)->cmd_queue.head)
 619
 620 /*
 621  * The request function is our main entry point
 622  */
 623
 624 static void ub_request_fn(struct request_queue *q)
 625 {
 626         struct ub_lun *lun = q->queuedata;
 627         struct request *rq;
 628
 629         while ((rq = blk_peek_request(q)) != NULL) {
 630                 if (ub_request_fn_1(lun, rq) != 0) {
 631                         blk_stop_queue(q);
 632                         break;
 633                 }
 634         }
 635 }
 636
 637 static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
 638 {
 639         struct ub_dev *sc = lun->udev;
 640         struct ub_scsi_cmd *cmd;
 641         struct ub_request *urq;
 642         int n_elem;
 643
 644         if (atomic_read(&sc->poison)) {
 645                 blk_start_request(rq);
 646                 ub_end_rq(rq, DID_NO_CONNECT << 16);
 647                 return 0;
 648         }
 649
 650         if (lun->changed && !blk_pc_request(rq)) {
 651                 blk_start_request(rq);
 652                 ub_end_rq(rq, SAM_STAT_CHECK_CONDITION);
 653                 return 0;
 654         }
 655
 656         if (lun->urq.rq != NULL)
 657                 return -1;
 658         if ((cmd = ub_get_cmd(lun)) == NULL)
 659                 return -1;
 660         memset(cmd, 0, sizeof(struct ub_scsi_cmd));
 661
 662         blk_start_request(rq);
 663
 664         urq = &lun->urq;
 665         memset(urq, 0, sizeof(struct ub_request));
 666         urq->rq = rq;
 667
 668         /*
 669          * get scatterlist from block layer
 670          */
 671         sg_init_table(&urq->sgv[0], UB_MAX_REQ_SG);
 672         n_elem = blk_rq_map_sg(lun->disk->queue, rq, &urq->sgv[0]);
 673         if (n_elem < 0) {
 674                 /* Impossible, because blk_rq_map_sg should not hit ENOMEM. */
 675                 printk(KERN_INFO "%s: failed request map (%d)\n",
 676                     lun->name, n_elem);
 677                 goto drop;
 678         }
 679         if (n_elem > UB_MAX_REQ_SG) {   /* Paranoia */
 680                 printk(KERN_WARNING "%s: request with %d segments\n",
 681                     lun->name, n_elem);
 682                 goto drop;
 683         }
 684         urq->nsg = n_elem;
 685
 686         if (blk_pc_request(rq)) {
 687                 ub_cmd_build_packet(sc, lun, cmd, urq);
 688         } else {
 689                 ub_cmd_build_block(sc, lun, cmd, urq);
 690         }
 691         cmd->state = UB_CMDST_INIT;
 692         cmd->lun = lun;
 693         cmd->done = ub_rw_cmd_done;
 694         cmd->back = urq;
 695
 696         cmd->tag = sc->tagcnt++;
 697         if (ub_submit_scsi(sc, cmd) != 0)
 698                 goto drop;
 699
 700         return 0;
 701
 702 drop:
 703         ub_put_cmd(lun, cmd);
 704         ub_end_rq(rq, DID_ERROR << 16);
 705         return 0;
 706 }
 707
 708 static void ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
 709     struct ub_scsi_cmd *cmd, struct ub_request *urq)
 710 {
 711         struct request *rq = urq->rq;
 712         unsigned int block, nblks;
 713
 714         if (rq_data_dir(rq) == WRITE)
 715                 cmd->dir = UB_DIR_WRITE;
 716         else
 717                 cmd->dir = UB_DIR_READ;
 718
 719         cmd->nsg = urq->nsg;
 720         memcpy(cmd->sgv, urq->sgv, sizeof(struct scatterlist) * cmd->nsg);
 721
 722         /*
 723          * build the command
 724          *
 725          * The call to blk_queue_logical_block_size() guarantees that request
 726          * is aligned, but it is given in terms of 512 byte units, always.
 727          */
 728         block = blk_rq_pos(rq) >> lun->capacity.bshift;
 729         nblks = blk_rq_sectors(rq) >> lun->capacity.bshift;
 730
 731         cmd->cdb[0] = (cmd->dir == UB_DIR_READ)? READ_10: WRITE_10;
 732         /* 10-byte uses 4 bytes of LBA: 2147483648KB, 2097152MB, 2048GB */
 733         cmd->cdb[2] = block >> 24;
 734         cmd->cdb[3] = block >> 16;
 735         cmd->cdb[4] = block >> 8;
 736         cmd->cdb[5] = block;
 737         cmd->cdb[7] = nblks >> 8;
 738         cmd->cdb[8] = nblks;
 739         cmd->cdb_len = 10;
 740
 741         cmd->len = blk_rq_bytes(rq);
 742 }
 743
 744 static void ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
 745     struct ub_scsi_cmd *cmd, struct ub_request *urq)
 746 {
 747         struct request *rq = urq->rq;
 748
 749         if (blk_rq_bytes(rq) == 0) {
 750                 cmd->dir = UB_DIR_NONE;
 751         } else {
 752                 if (rq_data_dir(rq) == WRITE)
 753                         cmd->dir = UB_DIR_WRITE;
 754                 else
 755                         cmd->dir = UB_DIR_READ;
 756         }
 757
 758         cmd->nsg = urq->nsg;
 759         memcpy(cmd->sgv, urq->sgv, sizeof(struct scatterlist) * cmd->nsg);
 760
 761         memcpy(&cmd->cdb, rq->cmd, rq->cmd_len);
 762         cmd->cdb_len = rq->cmd_len;
 763
 764         cmd->len = blk_rq_bytes(rq);
 765
 766         /*
 767          * To reapply this to every URB is not as incorrect as it looks.
 768          * In return, we avoid any complicated tracking calculations.
 769          */
 770         cmd->timeo = rq->timeout;
 771 }
 772
 773 static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 774 {
 775         struct ub_lun *lun = cmd->lun;
 776         struct ub_request *urq = cmd->back;
 777         struct request *rq;
 778         unsigned int scsi_status;
 779
 780         rq = urq->rq;
 781
 782         if (cmd->error == 0) {
 783                 if (blk_pc_request(rq)) {
 784                         if (cmd->act_len >= rq->resid_len)
 785                                 rq->resid_len = 0;
 786                         else
 787                                 rq->resid_len -= cmd->act_len;
 788                         scsi_status = 0;
 789                 } else {
 790                         if (cmd->act_len != cmd->len) {
 791                                 scsi_status = SAM_STAT_CHECK_CONDITION;
 792                         } else {
 793                                 scsi_status = 0;
 794                         }
 795                 }
 796         } else {
 797                 if (blk_pc_request(rq)) {
 798                         /* UB_SENSE_SIZE is smaller than SCSI_SENSE_BUFFERSIZE */
 799                         memcpy(rq->sense, sc->top_sense, UB_SENSE_SIZE);
 800                         rq->sense_len = UB_SENSE_SIZE;
 801                         if (sc->top_sense[0] != 0)
 802                                 scsi_status = SAM_STAT_CHECK_CONDITION;
 803                         else
 804                                 scsi_status = DID_ERROR << 16;
 805                 } else {
 806                         if (cmd->error == -EIO &&
 807                             (cmd->key == 0 ||
 808                              cmd->key == MEDIUM_ERROR ||
 809                              cmd->key == UNIT_ATTENTION)) {
 810                                 if (ub_rw_cmd_retry(sc, lun, urq, cmd) == 0)
 811                                         return;
 812                         }
 813                         scsi_status = SAM_STAT_CHECK_CONDITION;
 814                 }
 815         }
 816
 817         urq->rq = NULL;
 818
 819         ub_put_cmd(lun, cmd);
 820         ub_end_rq(rq, scsi_status);
 821         blk_start_queue(lun->disk->queue);
 822 }
 823
 824 static void ub_end_rq(struct request *rq, unsigned int scsi_status)
 825 {
 826         int error;
 827
 828         if (scsi_status == 0) {
 829                 error = 0;
 830         } else {
 831                 error = -EIO;
 832                 rq->errors = scsi_status;
 833         }
 834         __blk_end_request_all(rq, error);
 835 }
 836
 837 static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
 838     struct ub_request *urq, struct ub_scsi_cmd *cmd)
 839 {
 840
 841         if (atomic_read(&sc->poison))
 842                 return -ENXIO;
 843
 844         ub_reset_enter(sc, urq->current_try);
 845
 846         if (urq->current_try >= 3)
 847                 return -EIO;
 848         urq->current_try++;
 849
 850         /* Remove this if anyone complains of flooding. */
 851         printk(KERN_DEBUG "%s: dir %c len/act %d/%d "
 852             "[sense %x %02x %02x] retry %d\n",
 853             sc->name, UB_DIR_CHAR(cmd->dir), cmd->len, cmd->act_len,
 854             cmd->key, cmd->asc, cmd->ascq, urq->current_try);
 855
 856         memset(cmd, 0, sizeof(struct ub_scsi_cmd));
 857         ub_cmd_build_block(sc, lun, cmd, urq);
 858
 859         cmd->state = UB_CMDST_INIT;
 860         cmd->lun = lun;
 861         cmd->done = ub_rw_cmd_done;
 862         cmd->back = urq;
 863
 864         cmd->tag = sc->tagcnt++;
 865
 866 #if 0 /* Wasteful */
 867         return ub_submit_scsi(sc, cmd);
 868 #else
 869         ub_cmdq_add(sc, cmd);
 870         return 0;
 871 #endif
 872 }
 873
 874 /*
 875  * Submit a regular SCSI operation (not an auto-sense).
 876  *
 877  * The Iron Law of Good Submit Routine is:
 878  * Zero return - callback is done, Nonzero return - callback is not done.
 879  * No exceptions.
 880  *
 881  * Host is assumed locked.
 882  */
 883 static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 884 {
 885
 886         if (cmd->state != UB_CMDST_INIT ||
 887             (cmd->dir != UB_DIR_NONE && cmd->len == 0)) {
 888                 return -EINVAL;
 889         }
 890
 891         ub_cmdq_add(sc, cmd);
 892         /*
 893          * We can call ub_scsi_dispatch(sc) right away here, but it's a little
 894          * safer to jump to a tasklet, in case upper layers do something silly.
 895          */
 896         tasklet_schedule(&sc->tasklet);
 897         return 0;
 898 }
 899
 900 /*
 901  * Submit the first URB for the queued command.
 902  * This function does not deal with queueing in any way.
 903  */
 904 static int ub_scsi_cmd_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 905 {
 906         struct bulk_cb_wrap *bcb;
 907         int rc;
 908
 909         bcb = &sc->work_bcb;
 910
 911         /*
 912          * ``If the allocation length is eighteen or greater, and a device
 913          * server returns less than eithteen bytes of data, the application
 914          * client should assume that the bytes not transferred would have been
 915          * zeroes had the device server returned those bytes.''
 916          *
 917          * We zero sense for all commands so that when a packet request
 918          * fails it does not return a stale sense.
 919          */
 920         memset(&sc->top_sense, 0, UB_SENSE_SIZE);
 921
 922         /* set up the command wrapper */
 923         bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
 924         bcb->Tag = cmd->tag;            /* Endianness is not important */
 925         bcb->DataTransferLength = cpu_to_le32(cmd->len);
 926         bcb->Flags = (cmd->dir == UB_DIR_READ) ? 0x80 : 0;
 927         bcb->Lun = (cmd->lun != NULL) ? cmd->lun->num : 0;
 928         bcb->Length = cmd->cdb_len;
 929
 930         /* copy the command payload */
 931         memcpy(bcb->CDB, cmd->cdb, UB_MAX_CDB_SIZE);
 932
 933         UB_INIT_COMPLETION(sc->work_done);
 934
 935         sc->last_pipe = sc->send_bulk_pipe;
 936         usb_fill_bulk_urb(&sc->work_urb, sc->dev, sc->send_bulk_pipe,
 937             bcb, US_BULK_CB_WRAP_LEN, ub_urb_complete, sc);
 938
 939         if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
 940                 /* XXX Clear stalls */
 941                 ub_complete(&sc->work_done);
 942                 return rc;
 943         }
 944
 945         sc->work_timer.expires = jiffies + UB_URB_TIMEOUT;
 946         add_timer(&sc->work_timer);
 947
 948         cmd->state = UB_CMDST_CMD;
 949         return 0;
 950 }
 951
 952 /*
 953  * Timeout handler.
 954  */
 955 static void ub_urb_timeout(unsigned long arg)
 956 {
 957         struct ub_dev *sc = (struct ub_dev *) arg;
 958         unsigned long flags;
 959
 960         spin_lock_irqsave(sc->lock, flags);
 961         if (!ub_is_completed(&sc->work_done))
 962                 usb_unlink_urb(&sc->work_urb);
 963         spin_unlock_irqrestore(sc->lock, flags);
 964 }
 965
 966 /*
 967  * Completion routine for the work URB.
 968  *
 969  * This can be called directly from usb_submit_urb (while we have
 970  * the sc->lock taken) and from an interrupt (while we do NOT have
 971  * the sc->lock taken). Therefore, bounce this off to a tasklet.
 972  */
 973 static void ub_urb_complete(struct urb *urb)
 974 {
 975         struct ub_dev *sc = urb->context;
 976
 977         ub_complete(&sc->work_done);
 978         tasklet_schedule(&sc->tasklet);
 979 }
 980
 981 static void ub_scsi_action(unsigned long _dev)
 982 {
 983         struct ub_dev *sc = (struct ub_dev *) _dev;
 984         unsigned long flags;
 985
 986         spin_lock_irqsave(sc->lock, flags);
 987         ub_scsi_dispatch(sc);
 988         spin_unlock_irqrestore(sc->lock, flags);
 989 }
 990
 991 static void ub_scsi_dispatch(struct ub_dev *sc)
 992 {
 993         struct ub_scsi_cmd *cmd;
 994         int rc;
 995
 996         while (!sc->reset && (cmd = ub_cmdq_peek(sc)) != NULL) {
 997                 if (cmd->state == UB_CMDST_DONE) {
 998                         ub_cmdq_pop(sc);
 999                         (*cmd->done)(sc, cmd);
1000                 } else if (cmd->state == UB_CMDST_INIT) {
1001                         if ((rc = ub_scsi_cmd_start(sc, cmd)) == 0)
1002                                 break;
1003                         cmd->error = rc;
1004                         cmd->state = UB_CMDST_DONE;
1005                 } else {
1006                         if (!ub_is_completed(&sc->work_done))
1007                                 break;
1008                         del_timer(&sc->work_timer);
1009                         ub_scsi_urb_compl(sc, cmd);
1010                 }
1011         }
1012 }
1013
1014 static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1015 {
1016         struct urb *urb = &sc->work_urb;
1017         struct bulk_cs_wrap *bcs;
1018         int endp;
1019         int len;
1020         int rc;
1021
1022         if (atomic_read(&sc->poison)) {
1023                 ub_state_done(sc, cmd, -ENODEV);
1024                 return;
1025         }
1026
1027         endp = usb_pipeendpoint(sc->last_pipe);
1028         if (usb_pipein(sc->last_pipe))
1029                 endp |= USB_DIR_IN;
1030
1031         if (cmd->state == UB_CMDST_CLEAR) {
1032                 if (urb->status == -EPIPE) {
1033                         /*
1034                          * STALL while clearning STALL.
1035                          * The control pipe clears itself - nothing to do.
1036                          */
1037                         printk(KERN_NOTICE "%s: stall on control pipe\n",
1038                             sc->name);
1039                         goto Bad_End;
1040                 }
1041
1042                 /*
1043                  * We ignore the result for the halt clear.
1044                  */
1045
1046                 usb_reset_endpoint(sc->dev, endp);
1047
1048                 ub_state_sense(sc, cmd);
1049
1050         } else if (cmd->state == UB_CMDST_CLR2STS) {
1051                 if (urb->status == -EPIPE) {
1052                         printk(KERN_NOTICE "%s: stall on control pipe\n",
1053                             sc->name);
1054                         goto Bad_End;
1055                 }
1056
1057                 /*
1058                  * We ignore the result for the halt clear.
1059                  */
1060
1061                 usb_reset_endpoint(sc->dev, endp);
1062
1063                 ub_state_stat(sc, cmd);
1064
1065         } else if (cmd->state == UB_CMDST_CLRRS) {
1066                 if (urb->status == -EPIPE) {
1067                         printk(KERN_NOTICE "%s: stall on control pipe\n",
1068                             sc->name);
1069                         goto Bad_End;
1070                 }
1071
1072                 /*
1073                  * We ignore the result for the halt clear.
1074                  */
1075
1076                 usb_reset_endpoint(sc->dev, endp);
1077
1078                 ub_state_stat_counted(sc, cmd);
1079
1080         } else if (cmd->state == UB_CMDST_CMD) {
1081                 switch (urb->status) {
1082                 case 0:
1083                         break;
1084                 case -EOVERFLOW:
1085                         goto Bad_End;
1086                 case -EPIPE:
1087                         rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
1088                         if (rc != 0) {
1089                                 printk(KERN_NOTICE "%s: "
1090                                     "unable to submit clear (%d)\n",
1091                                     sc->name, rc);
1092                                 /*
1093                                  * This is typically ENOMEM or some other such shit.
1094                                  * Retrying is pointless. Just do Bad End on it...
1095                                  */
1096                                 ub_state_done(sc, cmd, rc);
1097                                 return;
1098                         }
1099                         cmd->state = UB_CMDST_CLEAR;
1100                         return;
1101                 case -ESHUTDOWN:        /* unplug */
1102                 case -EILSEQ:           /* unplug timeout on uhci */
1103                         ub_state_done(sc, cmd, -ENODEV);
1104                         return;
1105                 default:
1106                         goto Bad_End;
1107                 }
1108                 if (urb->actual_length != US_BULK_CB_WRAP_LEN) {
1109                         goto Bad_End;
1110                 }
1111
1112                 if (cmd->dir == UB_DIR_NONE || cmd->nsg < 1) {
1113                         ub_state_stat(sc, cmd);
1114                         return;
1115                 }
1116
1117                 // udelay(125);         // usb-storage has this
1118                 ub_data_start(sc, cmd);
1119
1120         } else if (cmd->state == UB_CMDST_DATA) {
1121                 if (urb->status == -EPIPE) {
1122                         rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
1123                         if (rc != 0) {
1124                                 printk(KERN_NOTICE "%s: "
1125                                     "unable to submit clear (%d)\n",
1126                                     sc->name, rc);
1127                                 ub_state_done(sc, cmd, rc);
1128                                 return;
1129                         }
1130                         cmd->state = UB_CMDST_CLR2STS;
1131                         return;
1132                 }
1133                 if (urb->status == -EOVERFLOW) {
1134                         /*
1135                          * A babble? Failure, but we must transfer CSW now.
1136                          */
1137                         cmd->error = -EOVERFLOW;        /* A cheap trick... */
1138                         ub_state_stat(sc, cmd);
1139                         return;
1140                 }
1141
1142                 if (cmd->dir == UB_DIR_WRITE) {
1143                         /*
1144                          * Do not continue writes in case of a failure.
1145                          * Doing so would cause sectors to be mixed up,
1146                          * which is worse than sectors lost.
1147                          *
1148                          * We must try to read the CSW, or many devices
1149                          * get confused.
1150                          */
1151                         len = urb->actual_length;
1152                         if (urb->status != 0 ||
1153                             len != cmd->sgv[cmd->current_sg].length) {
1154                                 cmd->act_len += len;
1155
1156                                 cmd->error = -EIO;
1157                                 ub_state_stat(sc, cmd);
1158                                 return;
1159                         }
1160
1161                 } else {
1162                         /*
1163                          * If an error occurs on read, we record it, and
1164                          * continue to fetch data in order to avoid bubble.
1165                          *
1166                          * As a small shortcut, we stop if we detect that
1167                          * a CSW mixed into data.
1168                          */
1169                         if (urb->status != 0)
1170                                 cmd->error = -EIO;
1171
1172                         len = urb->actual_length;
1173                         if (urb->status != 0 ||
1174                             len != cmd->sgv[cmd->current_sg].length) {
1175                                 if ((len & 0x1FF) == US_BULK_CS_WRAP_LEN)
1176                                         goto Bad_End;
1177                         }
1178                 }
1179
1180                 cmd->act_len += urb->actual_length;
1181
1182                 if (++cmd->current_sg < cmd->nsg) {
1183                         ub_data_start(sc, cmd);
1184                         return;
1185                 }
1186                 ub_state_stat(sc, cmd);
1187
1188         } else if (cmd->state == UB_CMDST_STAT) {
1189                 if (urb->status == -EPIPE) {
1190                         rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
1191                         if (rc != 0) {
1192                                 printk(KERN_NOTICE "%s: "
1193                                     "unable to submit clear (%d)\n",
1194                                     sc->name, rc);
1195                                 ub_state_done(sc, cmd, rc);
1196                                 return;
1197                         }
1198
1199                         /*
1200                          * Having a stall when getting CSW is an error, so
1201                          * make sure uppper levels are not oblivious to it.
1202                          */
1203                         cmd->error = -EIO;              /* A cheap trick... */
1204
1205                         cmd->state = UB_CMDST_CLRRS;
1206                         return;
1207                 }
1208
1209                 /* Catch everything, including -EOVERFLOW and other nasties. */
1210                 if (urb->status != 0)
1211                         goto Bad_End;
1212
1213                 if (urb->actual_length == 0) {
1214                         ub_state_stat_counted(sc, cmd);
1215                         return;
1216                 }
1217
1218                 /*
1219                  * Check the returned Bulk protocol status.
1220                  * The status block has to be validated first.
1221                  */
1222
1223                 bcs = &sc->work_bcs;
1224
1225                 if (sc->signature == cpu_to_le32(0)) {
1226                         /*
1227                          * This is the first reply, so do not perform the check.
1228                          * Instead, remember the signature the device uses
1229                          * for future checks. But do not allow a nul.
1230                          */
1231                         sc->signature = bcs->Signature;
1232                         if (sc->signature == cpu_to_le32(0)) {
1233                                 ub_state_stat_counted(sc, cmd);
1234                                 return;
1235                         }
1236                 } else {
1237                         if (bcs->Signature != sc->signature) {
1238                                 ub_state_stat_counted(sc, cmd);
1239                                 return;
1240                         }
1241                 }
1242
1243                 if (bcs->Tag != cmd->tag) {
1244                         /*
1245                          * This usually happens when we disagree with the
1246                          * device's microcode about something. For instance,
1247                          * a few of them throw this after timeouts. They buffer
1248                          * commands and reply at commands we timed out before.
1249                          * Without flushing these replies we loop forever.
1250                          */
1251                         ub_state_stat_counted(sc, cmd);
1252                         return;
1253                 }
1254
1255                 if (!sc->bad_resid) {
1256                         len = le32_to_cpu(bcs->Residue);
1257                         if (len != cmd->len - cmd->act_len) {
1258                                 /*
1259                                  * Only start ignoring if this cmd ended well.
1260                                  */
1261                                 if (cmd->len == cmd->act_len) {
1262                                         printk(KERN_NOTICE "%s: "
1263                                             "bad residual %d of %d, ignoring\n",
1264                                             sc->name, len, cmd->len);
1265                                         sc->bad_resid = 1;
1266                                 }
1267                         }
1268                 }
1269
1270                 switch (bcs->Status) {
1271                 case US_BULK_STAT_OK:
1272                         break;
1273                 case US_BULK_STAT_FAIL:
1274                         ub_state_sense(sc, cmd);
1275                         return;
1276                 case US_BULK_STAT_PHASE:
1277                         goto Bad_End;
1278                 default:
1279                         printk(KERN_INFO "%s: unknown CSW status 0x%x\n",
1280                             sc->name, bcs->Status);
1281                         ub_state_done(sc, cmd, -EINVAL);
1282                         return;
1283                 }
1284
1285                 /* Not zeroing error to preserve a babble indicator */
1286                 if (cmd->error != 0) {
1287                         ub_state_sense(sc, cmd);
1288                         return;
1289                 }
1290                 cmd->state = UB_CMDST_DONE;
1291                 ub_cmdq_pop(sc);
1292                 (*cmd->done)(sc, cmd);
1293
1294         } else if (cmd->state == UB_CMDST_SENSE) {
1295                 ub_state_done(sc, cmd, -EIO);
1296
1297         } else {
1298                 printk(KERN_WARNING "%s: wrong command state %d\n",
1299                     sc->name, cmd->state);
1300                 ub_state_done(sc, cmd, -EINVAL);
1301                 return;
1302         }
1303         return;
1304
1305 Bad_End: /* Little Excel is dead */
1306         ub_state_done(sc, cmd, -EIO);
1307 }
1308
1309 /*
1310  * Factorization helper for the command state machine:
1311  * Initiate a data segment transfer.
1312  */
1313 static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1314 {
1315         struct scatterlist *sg = &cmd->sgv[cmd->current_sg];
1316         int pipe;
1317         int rc;
1318
1319         UB_INIT_COMPLETION(sc->work_done);
1320
1321         if (cmd->dir == UB_DIR_READ)
1322                 pipe = sc->recv_bulk_pipe;
1323         else
1324                 pipe = sc->send_bulk_pipe;
1325         sc->last_pipe = pipe;
1326         usb_fill_bulk_urb(&sc->work_urb, sc->dev, pipe, sg_virt(sg),
1327             sg->length, ub_urb_complete, sc);
1328
1329         if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
1330                 /* XXX Clear stalls */
1331                 ub_complete(&sc->work_done);
1332                 ub_state_done(sc, cmd, rc);
1333                 return;
1334         }
1335
1336         if (cmd->timeo)
1337                 sc->work_timer.expires = jiffies + cmd->timeo;
1338         else
1339                 sc->work_timer.expires = jiffies + UB_DATA_TIMEOUT;
1340         add_timer(&sc->work_timer);
1341
1342         cmd->state = UB_CMDST_DATA;
1343 }
1344
1345 /*
1346  * Factorization helper for the command state machine:
1347  * Finish the command.
1348  */
1349 static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc)
1350 {
1351
1352         cmd->error = rc;
1353         cmd->state = UB_CMDST_DONE;
1354         ub_cmdq_pop(sc);
1355         (*cmd->done)(sc, cmd);
1356 }
1357
1358 /*
1359  * Factorization helper for the command state machine:
1360  * Submit a CSW read.
1361  */
1362 static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1363 {
1364         int rc;
1365
1366         UB_INIT_COMPLETION(sc->work_done);
1367
1368         sc->last_pipe = sc->recv_bulk_pipe;
1369         usb_fill_bulk_urb(&sc->work_urb, sc->dev, sc->recv_bulk_pipe,
1370             &sc->work_bcs, US_BULK_CS_WRAP_LEN, ub_urb_complete, sc);
1371
1372         if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
1373                 /* XXX Clear stalls */
1374                 ub_complete(&sc->work_done);
1375                 ub_state_done(sc, cmd, rc);
1376                 return -1;
1377         }
1378
1379         if (cmd->timeo)
1380                 sc->work_timer.expires = jiffies + cmd->timeo;
1381         else
1382                 sc->work_timer.expires = jiffies + UB_STAT_TIMEOUT;
1383         add_timer(&sc->work_timer);
1384         return 0;
1385 }
1386
1387 /*
1388  * Factorization helper for the command state machine:
1389  * Submit a CSW read and go to STAT state.
1390  */
1391 static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1392 {
1393
1394         if (__ub_state_stat(sc, cmd) != 0)
1395                 return;
1396
1397         cmd->stat_count = 0;
1398         cmd->state = UB_CMDST_STAT;
1399 }
1400
1401 /*
1402  * Factorization helper for the command state machine:
1403  * Submit a CSW read and go to STAT state with counter (along [C] path).
1404  */
1405 static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1406 {
1407
1408         if (++cmd->stat_count >= 4) {
1409                 ub_state_sense(sc, cmd);
1410                 return;
1411         }
1412
1413         if (__ub_state_stat(sc, cmd) != 0)
1414                 return;
1415
1416         cmd->state = UB_CMDST_STAT;
1417 }
1418
1419 /*
1420  * Factorization helper for the command state machine:
1421  * Submit a REQUEST SENSE and go to SENSE state.
1422  */
1423 static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1424 {
1425         struct ub_scsi_cmd *scmd;
1426         struct scatterlist *sg;
1427         int rc;
1428
1429         if (cmd->cdb[0] == REQUEST_SENSE) {
1430                 rc = -EPIPE;
1431                 goto error;
1432         }
1433
1434         scmd = &sc->top_rqs_cmd;
1435         memset(scmd, 0, sizeof(struct ub_scsi_cmd));
1436         scmd->cdb[0] = REQUEST_SENSE;
1437         scmd->cdb[4] = UB_SENSE_SIZE;
1438         scmd->cdb_len = 6;
1439         scmd->dir = UB_DIR_READ;
1440         scmd->state = UB_CMDST_INIT;
1441         scmd->nsg = 1;
1442         sg = &scmd->sgv[0];
1443         sg_init_table(sg, UB_MAX_REQ_SG);
1444         sg_set_page(sg, virt_to_page(sc->top_sense), UB_SENSE_SIZE,
1445                         (unsigned long)sc->top_sense & (PAGE_SIZE-1));
1446         scmd->len = UB_SENSE_SIZE;
1447         scmd->lun = cmd->lun;
1448         scmd->done = ub_top_sense_done;
1449         scmd->back = cmd;
1450
1451         scmd->tag = sc->tagcnt++;
1452
1453         cmd->state = UB_CMDST_SENSE;
1454
1455         ub_cmdq_insert(sc, scmd);
1456         return;
1457
1458 error:
1459         ub_state_done(sc, cmd, rc);
1460 }
1461
1462 /*
1463  * A helper for the command's state machine:
1464  * Submit a stall clear.
1465  */
1466 static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
1467     int stalled_pipe)
1468 {
1469         int endp;
1470         struct usb_ctrlrequest *cr;
1471         int rc;
1472
1473         endp = usb_pipeendpoint(stalled_pipe);
1474         if (usb_pipein (stalled_pipe))
1475                 endp |= USB_DIR_IN;
1476
1477         cr = &sc->work_cr;
1478         cr->bRequestType = USB_RECIP_ENDPOINT;
1479         cr->bRequest = USB_REQ_CLEAR_FEATURE;
1480         cr->wValue = cpu_to_le16(USB_ENDPOINT_HALT);
1481         cr->wIndex = cpu_to_le16(endp);
1482         cr->wLength = cpu_to_le16(0);
1483
1484         UB_INIT_COMPLETION(sc->work_done);
1485
1486         usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
1487             (unsigned char*) cr, NULL, 0, ub_urb_complete, sc);
1488
1489         if ((rc = usb_submit_urb(&sc->work_urb, GFP_ATOMIC)) != 0) {
1490                 ub_complete(&sc->work_done);
1491                 return rc;
1492         }
1493
1494         sc->work_timer.expires = jiffies + UB_CTRL_TIMEOUT;
1495         add_timer(&sc->work_timer);
1496         return 0;
1497 }
1498
1499 /*
1500  */
1501 static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd)
1502 {
1503         unsigned char *sense = sc->top_sense;
1504         struct ub_scsi_cmd *cmd;
1505
1506         /*
1507          * Find the command which triggered the unit attention or a check,
1508          * save the sense into it, and advance its state machine.
1509          */
1510         if ((cmd = ub_cmdq_peek(sc)) == NULL) {
1511                 printk(KERN_WARNING "%s: sense done while idle\n", sc->name);
1512                 return;
1513         }
1514         if (cmd != scmd->back) {
1515                 printk(KERN_WARNING "%s: "
1516                     "sense done for wrong command 0x%x\n",
1517                     sc->name, cmd->tag);
1518                 return;
1519         }
1520         if (cmd->state != UB_CMDST_SENSE) {
1521                 printk(KERN_WARNING "%s: sense done with bad cmd state %d\n",
1522                     sc->name, cmd->state);
1523                 return;
1524         }
1525
1526         /*
1527          * Ignoring scmd->act_len, because the buffer was pre-zeroed.
1528          */
1529         cmd->key = sense[2] & 0x0F;
1530         cmd->asc = sense[12];
1531         cmd->ascq = sense[13];
1532
1533         ub_scsi_urb_compl(sc, cmd);
1534 }
1535
1536 /*
1537  * Reset management
1538  */
1539
1540 static void ub_reset_enter(struct ub_dev *sc, int try)
1541 {
1542
1543         if (sc->reset) {
1544                 /* This happens often on multi-LUN devices. */
1545                 return;
1546         }
1547         sc->reset = try + 1;
1548
1549 #if 0 /* Not needed because the disconnect waits for us. */
1550         unsigned long flags;
1551         spin_lock_irqsave(&ub_lock, flags);
1552         sc->openc++;
1553         spin_unlock_irqrestore(&ub_lock, flags);
1554 #endif
1555
1556 #if 0 /* We let them stop themselves. */
1557         struct ub_lun *lun;
1558         list_for_each_entry(lun, &sc->luns, link) {
1559                 blk_stop_queue(lun->disk->queue);
1560         }
1561 #endif
1562
1563         schedule_work(&sc->reset_work);
1564 }
1565
1566 static void ub_reset_task(struct work_struct *work)
1567 {
1568         struct ub_dev *sc = container_of(work, struct ub_dev, reset_work);
1569         unsigned long flags;
1570         struct ub_lun *lun;
1571         int rc;
1572
1573         if (!sc->reset) {
1574                 printk(KERN_WARNING "%s: Running reset unrequested\n",
1575                     sc->name);
1576                 return;
1577         }
1578
1579         if (atomic_read(&sc->poison)) {
1580                 ;
1581         } else if ((sc->reset & 1) == 0) {
1582                 ub_sync_reset(sc);
1583                 msleep(700);    /* usb-storage sleeps 6s (!) */
1584                 ub_probe_clear_stall(sc, sc->recv_bulk_pipe);
1585                 ub_probe_clear_stall(sc, sc->send_bulk_pipe);
1586         } else if (sc->dev->actconfig->desc.bNumInterfaces != 1) {
1587                 ;
1588         } else {
1589                 rc = usb_lock_device_for_reset(sc->dev, sc->intf);
1590                 if (rc < 0) {
1591                         printk(KERN_NOTICE
1592                             "%s: usb_lock_device_for_reset failed (%d)\n",
1593                             sc->name, rc);
1594                 } else {
1595                         rc = usb_reset_device(sc->dev);
1596                         if (rc < 0) {
1597                                 printk(KERN_NOTICE "%s: "
1598                                     "usb_lock_device_for_reset failed (%d)\n",
1599                                     sc->name, rc);
1600                         }
1601                         usb_unlock_device(sc->dev);
1602                 }
1603         }
1604
1605         /*
1606          * In theory, no commands can be running while reset is active,
1607          * so nobody can ask for another reset, and so we do not need any
1608          * queues of resets or anything. We do need a spinlock though,
1609          * to interact with block layer.
1610          */
1611         spin_lock_irqsave(sc->lock, flags);
1612         sc->reset = 0;
1613         tasklet_schedule(&sc->tasklet);
1614         list_for_each_entry(lun, &sc->luns, link) {
1615                 blk_start_queue(lun->disk->queue);
1616         }
1617         wake_up(&sc->reset_wait);
1618         spin_unlock_irqrestore(sc->lock, flags);
1619 }
1620
1621 /*
1622  * XXX Reset brackets are too much hassle to implement, so just stub them
1623  * in order to prevent forced unbinding (which deadlocks solid when our
1624  * ->disconnect method waits for the reset to complete and this kills keventd).
1625  *
1626  * XXX Tell Alan to move usb_unlock_device inside of usb_reset_device,
1627  * or else the post_reset is invoked, and restats I/O on a locked device.
1628  */
1629 static int ub_pre_reset(struct usb_interface *iface) {
1630         return 0;
1631 }
1632
1633 static int ub_post_reset(struct usb_interface *iface) {
1634         return 0;
1635 }
1636
1637 /*
1638  * This is called from a process context.
1639  */
1640 static void ub_revalidate(struct ub_dev *sc, struct ub_lun *lun)
1641 {
1642
1643         lun->readonly = 0;      /* XXX Query this from the device */
1644
1645         lun->capacity.nsec = 0;
1646         lun->capacity.bsize = 512;
1647         lun->capacity.bshift = 0;
1648
1649         if (ub_sync_tur(sc, lun) != 0)
1650                 return;                 /* Not ready */
1651         lun->changed = 0;
1652
1653         if (ub_sync_read_cap(sc, lun, &lun->capacity) != 0) {
1654                 /*
1655                  * The retry here means something is wrong, either with the
1656                  * device, with the transport, or with our code.
1657                  * We keep this because sd.c has retries for capacity.
1658                  */
1659                 if (ub_sync_read_cap(sc, lun, &lun->capacity) != 0) {
1660                         lun->capacity.nsec = 0;
1661                         lun->capacity.bsize = 512;
1662                         lun->capacity.bshift = 0;
1663                 }
1664         }
1665 }
1666
1667 /*
1668  * The open funcion.
1669  * This is mostly needed to keep refcounting, but also to support
1670  * media checks on removable media drives.
1671  */
1672 static int ub_bd_open(struct block_device *bdev, fmode_t mode)
1673 {
1674         struct ub_lun *lun = bdev->bd_disk->private_data;
1675         struct ub_dev *sc = lun->udev;
1676         unsigned long flags;
1677         int rc;
1678
1679         spin_lock_irqsave(&ub_lock, flags);
1680         if (atomic_read(&sc->poison)) {
1681                 spin_unlock_irqrestore(&ub_lock, flags);
1682                 return -ENXIO;
1683         }
1684         sc->openc++;
1685         spin_unlock_irqrestore(&ub_lock, flags);
1686
1687         if (lun->removable || lun->readonly)
1688                 check_disk_change(bdev);
1689
1690         /*
1691          * The sd.c considers ->media_present and ->changed not equivalent,
1692          * under some pretty murky conditions (a failure of READ CAPACITY).
1693          * We may need it one day.
1694          */
1695         if (lun->removable && lun->changed && !(mode & FMODE_NDELAY)) {
1696                 rc = -ENOMEDIUM;
1697                 goto err_open;
1698         }
1699
1700         if (lun->readonly && (mode & FMODE_WRITE)) {
1701                 rc = -EROFS;
1702                 goto err_open;
1703         }
1704
1705         return 0;
1706
1707 err_open:
1708         ub_put(sc);
1709         return rc;
1710 }
1711
1712 /*
1713  */
1714 static int ub_bd_release(struct gendisk *disk, fmode_t mode)
1715 {
1716         struct ub_lun *lun = disk->private_data;
1717         struct ub_dev *sc = lun->udev;
1718
1719         ub_put(sc);
1720         return 0;
1721 }
1722
1723 /*
1724  * The ioctl interface.
1725  */
1726 static int ub_bd_ioctl(struct block_device *bdev, fmode_t mode,
1727     unsigned int cmd, unsigned long arg)
1728 {
1729         struct gendisk *disk = bdev->bd_disk;
1730         void __user *usermem = (void __user *) arg;
1731
1732         return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, usermem);
1733 }
1734
1735 /*
1736  * This is called by check_disk_change if we reported a media change.
1737  * The main onjective here is to discover the features of the media such as
1738  * the capacity, read-only status, etc. USB storage generally does not
1739  * need to be spun up, but if we needed it, this would be the place.
1740  *
1741  * This call can sleep.
1742  *
1743  * The return code is not used.
1744  */
1745 static int ub_bd_revalidate(struct gendisk *disk)
1746 {
1747         struct ub_lun *lun = disk->private_data;
1748
1749         ub_revalidate(lun->udev, lun);
1750
1751         /* XXX Support sector size switching like in sr.c */
1752         blk_queue_logical_block_size(disk->queue, lun->capacity.bsize);
1753         set_capacity(disk, lun->capacity.nsec);
1754         // set_disk_ro(sdkp->disk, lun->readonly);
1755
1756         return 0;
1757 }
1758
1759 /*
1760  * The check is called by the block layer to verify if the media
1761  * is still available. It is supposed to be harmless, lightweight and
1762  * non-intrusive in case the media was not changed.
1763  *
1764  * This call can sleep.
1765  *
1766  * The return code is bool!
1767  */
1768 static int ub_bd_media_changed(struct gendisk *disk)
1769 {
1770         struct ub_lun *lun = disk->private_data;
1771
1772         if (!lun->removable)
1773                 return 0;
1774
1775         /*
1776          * We clean checks always after every command, so this is not
1777          * as dangerous as it looks. If the TEST_UNIT_READY fails here,
1778          * the device is actually not ready with operator or software
1779          * intervention required. One dangerous item might be a drive which
1780          * spins itself down, and come the time to write dirty pages, this
1781          * will fail, then block layer discards the data. Since we never
1782          * spin drives up, such devices simply cannot be used with ub anyway.
1783          */
1784         if (ub_sync_tur(lun->udev, lun) != 0) {
1785                 lun->changed = 1;
1786                 return 1;
1787         }
1788
1789         return lun->changed;
1790 }
1791
1792 static const struct block_device_operations ub_bd_fops = {
1793         .owner          = THIS_MODULE,
1794         .open           = ub_bd_open,
1795         .release        = ub_bd_release,
1796         .locked_ioctl   = ub_bd_ioctl,
1797         .media_changed  = ub_bd_media_changed,
1798         .revalidate_disk = ub_bd_revalidate,
1799 };
1800
1801 /*
1802  * Common ->done routine for commands executed synchronously.
1803  */
1804 static void ub_probe_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
1805 {
1806         struct completion *cop = cmd->back;
1807         complete(cop);
1808 }
1809
1810 /*
1811  * Test if the device has a check condition on it, synchronously.
1812  */
1813 static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun)
1814 {
1815         struct ub_scsi_cmd *cmd;
1816         enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) };
1817         unsigned long flags;
1818         struct completion compl;
1819         int rc;
1820
1821         init_completion(&compl);
1822
1823         rc = -ENOMEM;
1824         if ((cmd = kzalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
1825                 goto err_alloc;
1826
1827         cmd->cdb[0] = TEST_UNIT_READY;
1828         cmd->cdb_len = 6;
1829         cmd->dir = UB_DIR_NONE;
1830         cmd->state = UB_CMDST_INIT;
1831         cmd->lun = lun;                 /* This may be NULL, but that's ok */
1832         cmd->done = ub_probe_done;
1833         cmd->back = &compl;
1834
1835         spin_lock_irqsave(sc->lock, flags);
1836         cmd->tag = sc->tagcnt++;
1837
1838         rc = ub_submit_scsi(sc, cmd);
1839         spin_unlock_irqrestore(sc->lock, flags);
1840
1841         if (rc != 0)
1842                 goto err_submit;
1843
1844         wait_for_completion(&compl);
1845
1846         rc = cmd->error;
1847
1848         if (rc == -EIO && cmd->key != 0)        /* Retries for benh's key */
1849                 rc = cmd->key;
1850
1851 err_submit:
1852         kfree(cmd);
1853 err_alloc:
1854         return rc;
1855 }
1856
1857 /*
1858  * Read the SCSI capacity synchronously (for probing).
1859  */
1860 static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
1861     struct ub_capacity *ret)
1862 {
1863         struct ub_scsi_cmd *cmd;
1864         struct scatterlist *sg;
1865         char *p;
1866         enum { ALLOC_SIZE = sizeof(struct ub_scsi_cmd) + 8 };
1867         unsigned long flags;
1868         unsigned int bsize, shift;
1869         unsigned long nsec;
1870         struct completion compl;
1871         int rc;
1872
1873         init_completion(&compl);
1874
1875         rc = -ENOMEM;
1876         if ((cmd = kzalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
1877                 goto err_alloc;
1878         p = (char *)cmd + sizeof(struct ub_scsi_cmd);
1879
1880         cmd->cdb[0] = 0x25;
1881         cmd->cdb_len = 10;
1882         cmd->dir = UB_DIR_READ;
1883         cmd->state = UB_CMDST_INIT;
1884         cmd->nsg = 1;
1885         sg = &cmd->sgv[0];
1886         sg_init_table(sg, UB_MAX_REQ_SG);
1887         sg_set_page(sg, virt_to_page(p), 8, (unsigned long)p & (PAGE_SIZE-1));
1888         cmd->len = 8;
1889         cmd->lun = lun;
1890         cmd->done = ub_probe_done;
1891         cmd->back = &compl;
1892
1893         spin_lock_irqsave(sc->lock, flags);
1894         cmd->tag = sc->tagcnt++;
1895
1896         rc = ub_submit_scsi(sc, cmd);
1897         spin_unlock_irqrestore(sc->lock, flags);
1898
1899         if (rc != 0)
1900                 goto err_submit;
1901
1902         wait_for_completion(&compl);
1903
1904         if (cmd->error != 0) {
1905                 rc = -EIO;
1906                 goto err_read;
1907         }
1908         if (cmd->act_len != 8) {
1909                 rc = -EIO;
1910                 goto err_read;
1911         }
1912
1913         /* sd.c special-cases sector size of 0 to mean 512. Needed? Safe? */
1914         nsec = be32_to_cpu(*(__be32 *)p) + 1;
1915         bsize = be32_to_cpu(*(__be32 *)(p + 4));
1916         switch (bsize) {
1917         case 512:       shift = 0;      break;
1918         case 1024:      shift = 1;      break;
1919         case 2048:      shift = 2;      break;
1920         case 4096:      shift = 3;      break;
1921         default:
1922                 rc = -EDOM;
1923                 goto err_inv_bsize;
1924         }
1925
1926         ret->bsize = bsize;
1927         ret->bshift = shift;
1928         ret->nsec = nsec << shift;
1929         rc = 0;
1930
1931 err_inv_bsize:
1932 err_read:
1933 err_submit:
1934         kfree(cmd);
1935 err_alloc:
1936         return rc;
1937 }
1938
1939 /*
1940  */
1941 static void ub_probe_urb_complete(struct urb *urb)
1942 {
1943         struct completion *cop = urb->context;
1944         complete(cop);
1945 }
1946
1947 static void ub_probe_timeout(unsigned long arg)
1948 {
1949         struct completion *cop = (struct completion *) arg;
1950         complete(cop);
1951 }
1952
1953 /*
1954  * Reset with a Bulk reset.
1955  */
1956 static int ub_sync_reset(struct ub_dev *sc)
1957 {
1958         int ifnum = sc->intf->cur_altsetting->desc.bInterfaceNumber;
1959         struct usb_ctrlrequest *cr;
1960         struct completion compl;
1961         struct timer_list timer;
1962         int rc;
1963
1964         init_completion(&compl);
1965
1966         cr = &sc->work_cr;
1967         cr->bRequestType = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
1968         cr->bRequest = US_BULK_RESET_REQUEST;
1969         cr->wValue = cpu_to_le16(0);
1970         cr->wIndex = cpu_to_le16(ifnum);
1971         cr->wLength = cpu_to_le16(0);
1972
1973         usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
1974             (unsigned char*) cr, NULL, 0, ub_probe_urb_complete, &compl);
1975
1976         if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0) {
1977                 printk(KERN_WARNING
1978                      "%s: Unable to submit a bulk reset (%d)\n", sc->name, rc);
1979                 return rc;
1980         }
1981
1982         init_timer(&timer);
1983         timer.function = ub_probe_timeout;
1984         timer.data = (unsigned long) &compl;
1985         timer.expires = jiffies + UB_CTRL_TIMEOUT;
1986         add_timer(&timer);
1987
1988         wait_for_completion(&compl);
1989
1990         del_timer_sync(&timer);
1991         usb_kill_urb(&sc->work_urb);
1992
1993         return sc->work_urb.status;
1994 }
1995
1996 /*
1997  * Get number of LUNs by the way of Bulk GetMaxLUN command.
1998  */
1999 static int ub_sync_getmaxlun(struct ub_dev *sc)
2000 {
2001         int ifnum = sc->intf->cur_altsetting->desc.bInterfaceNumber;
2002         unsigned char *p;
2003         enum { ALLOC_SIZE = 1 };
2004         struct usb_ctrlrequest *cr;
2005         struct completion compl;
2006         struct timer_list timer;
2007         int nluns;
2008         int rc;
2009
2010         init_completion(&compl);
2011
2012         rc = -ENOMEM;
2013         if ((p = kmalloc(ALLOC_SIZE, GFP_KERNEL)) == NULL)
2014                 goto err_alloc;
2015         *p = 55;
2016
2017         cr = &sc->work_cr;
2018         cr->bRequestType = USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE;
2019         cr->bRequest = US_BULK_GET_MAX_LUN;
2020         cr->wValue = cpu_to_le16(0);
2021         cr->wIndex = cpu_to_le16(ifnum);
2022         cr->wLength = cpu_to_le16(1);
2023
2024         usb_fill_control_urb(&sc->work_urb, sc->dev, sc->recv_ctrl_pipe,
2025             (unsigned char*) cr, p, 1, ub_probe_urb_complete, &compl);
2026
2027         if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0)
2028                 goto err_submit;
2029
2030         init_timer(&timer);
2031         timer.function = ub_probe_timeout;
2032         timer.data = (unsigned long) &compl;
2033         timer.expires = jiffies + UB_CTRL_TIMEOUT;
2034         add_timer(&timer);
2035
2036         wait_for_completion(&compl);
2037
2038         del_timer_sync(&timer);
2039         usb_kill_urb(&sc->work_urb);
2040
2041         if ((rc = sc->work_urb.status) < 0)
2042                 goto err_io;
2043
2044         if (sc->work_urb.actual_length != 1) {
2045                 nluns = 0;
2046         } else {
2047                 if ((nluns = *p) == 55) {
2048                         nluns = 0;
2049                 } else {
2050                         /* GetMaxLUN returns the maximum LUN number */
2051                         nluns += 1;
2052                         if (nluns > UB_MAX_LUNS)
2053                                 nluns = UB_MAX_LUNS;
2054                 }
2055         }
2056
2057         kfree(p);
2058         return nluns;
2059
2060 err_io:
2061 err_submit:
2062         kfree(p);
2063 err_alloc:
2064         return rc;
2065 }
2066
2067 /*
2068  * Clear initial stalls.
2069  */
2070 static int ub_probe_clear_stall(struct ub_dev *sc, int stalled_pipe)
2071 {
2072         int endp;
2073         struct usb_ctrlrequest *cr;
2074         struct completion compl;
2075         struct timer_list timer;
2076         int rc;
2077
2078         init_completion(&compl);
2079
2080         endp = usb_pipeendpoint(stalled_pipe);
2081         if (usb_pipein (stalled_pipe))
2082                 endp |= USB_DIR_IN;
2083
2084         cr = &sc->work_cr;
2085         cr->bRequestType = USB_RECIP_ENDPOINT;
2086         cr->bRequest = USB_REQ_CLEAR_FEATURE;
2087         cr->wValue = cpu_to_le16(USB_ENDPOINT_HALT);
2088         cr->wIndex = cpu_to_le16(endp);
2089         cr->wLength = cpu_to_le16(0);
2090
2091         usb_fill_control_urb(&sc->work_urb, sc->dev, sc->send_ctrl_pipe,
2092             (unsigned char*) cr, NULL, 0, ub_probe_urb_complete, &compl);
2093
2094         if ((rc = usb_submit_urb(&sc->work_urb, GFP_KERNEL)) != 0) {
2095                 printk(KERN_WARNING
2096                      "%s: Unable to submit a probe clear (%d)\n", sc->name, rc);
2097                 return rc;
2098         }
2099
2100         init_timer(&timer);
2101         timer.function = ub_probe_timeout;
2102         timer.data = (unsigned long) &compl;
2103         timer.expires = jiffies + UB_CTRL_TIMEOUT;
2104         add_timer(&timer);
2105
2106         wait_for_completion(&compl);
2107
2108         del_timer_sync(&timer);
2109         usb_kill_urb(&sc->work_urb);
2110
2111         usb_reset_endpoint(sc->dev, endp);
2112
2113         return 0;
2114 }
2115
2116 /*
2117  * Get the pipe settings.
2118  */
2119 static int ub_get_pipes(struct ub_dev *sc, struct usb_device *dev,
2120     struct usb_interface *intf)
2121 {
2122         struct usb_host_interface *altsetting = intf->cur_altsetting;
2123         struct usb_endpoint_descriptor *ep_in = NULL;
2124         struct usb_endpoint_descriptor *ep_out = NULL;
2125         struct usb_endpoint_descriptor *ep;
2126         int i;
2127
2128         /*
2129          * Find the endpoints we need.
2130          * We are expecting a minimum of 2 endpoints - in and out (bulk).
2131          * We will ignore any others.
2132          */
2133         for (i = 0; i < altsetting->desc.bNumEndpoints; i++) {
2134                 ep = &altsetting->endpoint[i].desc;
2135
2136                 /* Is it a BULK endpoint? */
2137                 if (usb_endpoint_xfer_bulk(ep)) {
2138                         /* BULK in or out? */
2139                         if (usb_endpoint_dir_in(ep)) {
2140                                 if (ep_in == NULL)
2141                                         ep_in = ep;
2142                         } else {
2143                                 if (ep_out == NULL)
2144                                         ep_out = ep;
2145                         }
2146                 }
2147         }
2148
2149         if (ep_in == NULL || ep_out == NULL) {
2150                 printk(KERN_NOTICE "%s: failed endpoint check\n", sc->name);
2151                 return -ENODEV;
2152         }
2153
2154         /* Calculate and store the pipe values */
2155         sc->send_ctrl_pipe = usb_sndctrlpipe(dev, 0);
2156         sc->recv_ctrl_pipe = usb_rcvctrlpipe(dev, 0);
2157         sc->send_bulk_pipe = usb_sndbulkpipe(dev,
2158                 usb_endpoint_num(ep_out));
2159         sc->recv_bulk_pipe = usb_rcvbulkpipe(dev,
2160                 usb_endpoint_num(ep_in));
2161
2162         return 0;
2163 }
2164
2165 /*
2166  * Probing is done in the process context, which allows us to cheat
2167  * and not to build a state machine for the discovery.
2168  */
2169 static int ub_probe(struct usb_interface *intf,
2170     const struct usb_device_id *dev_id)
2171 {
2172         struct ub_dev *sc;
2173         int nluns;
2174         int rc;
2175         int i;
2176
2177         if (usb_usual_check_type(dev_id, USB_US_TYPE_UB))
2178                 return -ENXIO;
2179
2180         rc = -ENOMEM;
2181         if ((sc = kzalloc(sizeof(struct ub_dev), GFP_KERNEL)) == NULL)
2182                 goto err_core;
2183         sc->lock = ub_next_lock();
2184         INIT_LIST_HEAD(&sc->luns);
2185         usb_init_urb(&sc->work_urb);
2186         tasklet_init(&sc->tasklet, ub_scsi_action, (unsigned long)sc);
2187         atomic_set(&sc->poison, 0);
2188         INIT_WORK(&sc->reset_work, ub_reset_task);
2189         init_waitqueue_head(&sc->reset_wait);
2190
2191         init_timer(&sc->work_timer);
2192         sc->work_timer.data = (unsigned long) sc;
2193         sc->work_timer.function = ub_urb_timeout;
2194
2195         ub_init_completion(&sc->work_done);
2196         sc->work_done.done = 1;         /* A little yuk, but oh well... */
2197
2198         sc->dev = interface_to_usbdev(intf);
2199         sc->intf = intf;
2200         // sc->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
2201         usb_set_intfdata(intf, sc);
2202         usb_get_dev(sc->dev);
2203         /*
2204          * Since we give the interface struct to the block level through
2205          * disk->driverfs_dev, we have to pin it. Otherwise, block_uevent
2206          * oopses on close after a disconnect (kernels 2.6.16 and up).
2207          */
2208         usb_get_intf(sc->intf);
2209
2210         snprintf(sc->name, 12, DRV_NAME "(%d.%d)",
2211             sc->dev->bus->busnum, sc->dev->devnum);
2212
2213         /* XXX Verify that we can handle the device (from descriptors) */
2214
2215         if (ub_get_pipes(sc, sc->dev, intf) != 0)
2216                 goto err_dev_desc;
2217
2218         /*
2219          * At this point, all USB initialization is done, do upper layer.
2220          * We really hate halfway initialized structures, so from the
2221          * invariants perspective, this ub_dev is fully constructed at
2222          * this point.
2223          */
2224
2225         /*
2226          * This is needed to clear toggles. It is a problem only if we do
2227          * `rmmod ub && modprobe ub` without disconnects, but we like that.
2228          */
2229 #if 0 /* iPod Mini fails if we do this (big white iPod works) */
2230         ub_probe_clear_stall(sc, sc->recv_bulk_pipe);
2231         ub_probe_clear_stall(sc, sc->send_bulk_pipe);
2232 #endif
2233
2234         /*
2235          * The way this is used by the startup code is a little specific.
2236          * A SCSI check causes a USB stall. Our common case code sees it
2237          * and clears the check, after which the device is ready for use.
2238          * But if a check was not present, any command other than
2239          * TEST_UNIT_READY ends with a lockup (including REQUEST_SENSE).
2240          *
2241          * If we neglect to clear the SCSI check, the first real command fails
2242          * (which is the capacity readout). We clear that and retry, but why
2243          * causing spurious retries for no reason.
2244          *
2245          * Revalidation may start with its own TEST_UNIT_READY, but that one
2246          * has to succeed, so we clear checks with an additional one here.
2247          * In any case it's not our business how revaliadation is implemented.
2248          */
2249         for (i = 0; i < 3; i++) {  /* Retries for the schwag key from KS'04 */
2250                 if ((rc = ub_sync_tur(sc, NULL)) <= 0) break;
2251                 if (rc != 0x6) break;
2252                 msleep(10);
2253         }
2254
2255         nluns = 1;
2256         for (i = 0; i < 3; i++) {
2257                 if ((rc = ub_sync_getmaxlun(sc)) < 0)
2258                         break;
2259                 if (rc != 0) {
2260                         nluns = rc;
2261                         break;
2262                 }
2263                 msleep(100);
2264         }
2265
2266         for (i = 0; i < nluns; i++) {
2267                 ub_probe_lun(sc, i);
2268         }
2269         return 0;
2270
2271 err_dev_desc:
2272         usb_set_intfdata(intf, NULL);
2273         usb_put_intf(sc->intf);
2274         usb_put_dev(sc->dev);
2275         kfree(sc);
2276 err_core:
2277         return rc;
2278 }
2279
2280 static int ub_probe_lun(struct ub_dev *sc, int lnum)
2281 {
2282         struct ub_lun *lun;
2283         struct request_queue *q;
2284         struct gendisk *disk;
2285         int rc;
2286
2287         rc = -ENOMEM;
2288         if ((lun = kzalloc(sizeof(struct ub_lun), GFP_KERNEL)) == NULL)
2289                 goto err_alloc;
2290         lun->num = lnum;
2291
2292         rc = -ENOSR;
2293         if ((lun->id = ub_id_get()) == -1)
2294                 goto err_id;
2295
2296         lun->udev = sc;
2297
2298         snprintf(lun->name, 16, DRV_NAME "%c(%d.%d.%d)",
2299             lun->id + 'a', sc->dev->bus->busnum, sc->dev->devnum, lun->num);
2300
2301         lun->removable = 1;             /* XXX Query this from the device */
2302         lun->changed = 1;               /* ub_revalidate clears only */
2303         ub_revalidate(sc, lun);
2304
2305         rc = -ENOMEM;
2306         if ((disk = alloc_disk(UB_PARTS_PER_LUN)) == NULL)
2307                 goto err_diskalloc;
2308
2309         sprintf(disk->disk_name, DRV_NAME "%c", lun->id + 'a');
2310         disk->major = UB_MAJOR;
2311         disk->first_minor = lun->id * UB_PARTS_PER_LUN;
2312         disk->fops = &ub_bd_fops;
2313         disk->private_data = lun;
2314         disk->driverfs_dev = &sc->intf->dev;
2315
2316         rc = -ENOMEM;
2317         if ((q = blk_init_queue(ub_request_fn, sc->lock)) == NULL)
2318                 goto err_blkqinit;
2319
2320         disk->queue = q;
2321
2322         blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
2323         blk_queue_max_hw_segments(q, UB_MAX_REQ_SG);
2324         blk_queue_max_phys_segments(q, UB_MAX_REQ_SG);
2325         blk_queue_segment_boundary(q, 0xffffffff);      /* Dubious. */
2326         blk_queue_max_sectors(q, UB_MAX_SECTORS);
2327         blk_queue_logical_block_size(q, lun->capacity.bsize);
2328
2329         lun->disk = disk;
2330         q->queuedata = lun;
2331         list_add(&lun->link, &sc->luns);
2332
2333         set_capacity(disk, lun->capacity.nsec);
2334         if (lun->removable)
2335                 disk->flags |= GENHD_FL_REMOVABLE;
2336
2337         add_disk(disk);
2338
2339         return 0;
2340
2341 err_blkqinit:
2342         put_disk(disk);
2343 err_diskalloc:
2344         ub_id_put(lun->id);
2345 err_id:
2346         kfree(lun);
2347 err_alloc:
2348         return rc;
2349 }
2350
2351 static void ub_disconnect(struct usb_interface *intf)
2352 {
2353         struct ub_dev *sc = usb_get_intfdata(intf);
2354         struct ub_lun *lun;
2355         unsigned long flags;
2356
2357         /*
2358          * Prevent ub_bd_release from pulling the rug from under us.
2359          * XXX This is starting to look like a kref.
2360          * XXX Why not to take this ref at probe time?
2361          */
2362         spin_lock_irqsave(&ub_lock, flags);
2363         sc->openc++;
2364         spin_unlock_irqrestore(&ub_lock, flags);
2365
2366         /*
2367          * Fence stall clearings, operations triggered by unlinkings and so on.
2368          * We do not attempt to unlink any URBs, because we do not trust the
2369          * unlink paths in HC drivers. Also, we get -84 upon disconnect anyway.
2370          */
2371         atomic_set(&sc->poison, 1);
2372
2373         /*
2374          * Wait for reset to end, if any.
2375          */
2376         wait_event(sc->reset_wait, !sc->reset);
2377
2378         /*
2379          * Blow away queued commands.
2380          *
2381          * Actually, this never works, because before we get here
2382          * the HCD terminates outstanding URB(s). It causes our
2383          * SCSI command queue to advance, commands fail to submit,
2384          * and the whole queue drains. So, we just use this code to
2385          * print warnings.
2386          */
2387         spin_lock_irqsave(sc->lock, flags);
2388         {
2389                 struct ub_scsi_cmd *cmd;
2390                 int cnt = 0;
2391                 while ((cmd = ub_cmdq_peek(sc)) != NULL) {
2392                         cmd->error = -ENOTCONN;
2393                         cmd->state = UB_CMDST_DONE;
2394                         ub_cmdq_pop(sc);
2395                         (*cmd->done)(sc, cmd);
2396                         cnt++;
2397                 }
2398                 if (cnt != 0) {
2399                         printk(KERN_WARNING "%s: "
2400                             "%d was queued after shutdown\n", sc->name, cnt);
2401                 }
2402         }
2403         spin_unlock_irqrestore(sc->lock, flags);
2404
2405         /*
2406          * Unregister the upper layer.
2407          */
2408         list_for_each_entry(lun, &sc->luns, link) {
2409                 del_gendisk(lun->disk);
2410                 /*
2411                  * I wish I could do:
2412                  *    queue_flag_set(QUEUE_FLAG_DEAD, q);
2413                  * As it is, we rely on our internal poisoning and let
2414                  * the upper levels to spin furiously failing all the I/O.
2415                  */
2416         }
2417
2418         /*
2419          * Testing for -EINPROGRESS is always a bug, so we are bending
2420          * the rules a little.
2421          */
2422         spin_lock_irqsave(sc->lock, flags);
2423         if (sc->work_urb.status == -EINPROGRESS) {      /* janitors: ignore */
2424                 printk(KERN_WARNING "%s: "
2425                     "URB is active after disconnect\n", sc->name);
2426         }
2427         spin_unlock_irqrestore(sc->lock, flags);
2428
2429         /*
2430          * There is virtually no chance that other CPU runs a timeout so long
2431          * after ub_urb_complete should have called del_timer, but only if HCD
2432          * didn't forget to deliver a callback on unlink.
2433          */
2434         del_timer_sync(&sc->work_timer);
2435
2436         /*
2437          * At this point there must be no commands coming from anyone
2438          * and no URBs left in transit.
2439          */
2440
2441         ub_put(sc);
2442 }
2443
2444 static struct usb_driver ub_driver = {
2445         .name =         "ub",
2446         .probe =        ub_probe,
2447         .disconnect =   ub_disconnect,
2448         .id_table =     ub_usb_ids,
2449         .pre_reset =    ub_pre_reset,
2450         .post_reset =   ub_post_reset,
2451 };
2452
2453 static int __init ub_init(void)
2454 {
2455         int rc;
2456         int i;
2457
2458         for (i = 0; i < UB_QLOCK_NUM; i++)
2459                 spin_lock_init(&ub_qlockv[i]);
2460
2461         if ((rc = register_blkdev(UB_MAJOR, DRV_NAME)) != 0)
2462                 goto err_regblkdev;
2463
2464         if ((rc = usb_register(&ub_driver)) != 0)
2465                 goto err_register;
2466
2467         usb_usual_set_present(USB_US_TYPE_UB);
2468         return 0;
2469
2470 err_register:
2471         unregister_blkdev(UB_MAJOR, DRV_NAME);
2472 err_regblkdev:
2473         return rc;
2474 }
2475
2476 static void __exit ub_exit(void)
2477 {
2478         usb_deregister(&ub_driver);
2479
2480         unregister_blkdev(UB_MAJOR, DRV_NAME);
2481         usb_usual_clear_present(USB_US_TYPE_UB);
2482 }
2483
2484 module_init(ub_init);
2485 module_exit(ub_exit);
2486
2487 MODULE_LICENSE("GPL");