drivers/usb/gadget/legacy/inode.c

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This source file includes following definitions.
get_dev
put_dev
dev_new
get_ep
put_ep
epio_complete
get_ready_ep
ep_io
ep_release
ep_ioctl
ep_aio_cancel
ep_user_copy_worker
ep_aio_complete
ep_aio
ep_read_iter
ep_write_iter
ep_config
ep_open
ep0_readable
clean_req
ep0_complete
setup_req
ep0_read
next_event
ep0_write
ep0_fasync
dev_release
ep0_poll
dev_ioctl
make_qualifier
config_buf
gadgetfs_setup
destroy_ep_files
activate_ep_files
gadgetfs_unbind
gadgetfs_bind
gadgetfs_disconnect
gadgetfs_suspend
is_valid_config
dev_config
dev_open
gadgetfs_make_inode
gadgetfs_create_file
gadgetfs_fill_super
gadgetfs_get_tree
gadgetfs_init_fs_context
gadgetfs_kill_sb
cleanup
   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * inode.c -- user mode filesystem api for usb gadget controllers
   4  *
   5  * Copyright (C) 2003-2004 David Brownell
   6  * Copyright (C) 2003 Agilent Technologies
   7  */
   8 
   9 
  10 /* #define VERBOSE_DEBUG */
  11 
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/fs.h>
  15 #include <linux/fs_context.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/uts.h>
  18 #include <linux/wait.h>
  19 #include <linux/compiler.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/sched.h>
  22 #include <linux/slab.h>
  23 #include <linux/poll.h>
  24 #include <linux/mmu_context.h>
  25 #include <linux/aio.h>
  26 #include <linux/uio.h>
  27 #include <linux/refcount.h>
  28 #include <linux/delay.h>
  29 #include <linux/device.h>
  30 #include <linux/moduleparam.h>
  31 
  32 #include <linux/usb/gadgetfs.h>
  33 #include <linux/usb/gadget.h>
  34 
  35 
  36 /*
  37  * The gadgetfs API maps each endpoint to a file descriptor so that you
  38  * can use standard synchronous read/write calls for I/O.  There's some
  39  * O_NONBLOCK and O_ASYNC/FASYNC style i/o support.  Example usermode
  40  * drivers show how this works in practice.  You can also use AIO to
  41  * eliminate I/O gaps between requests, to help when streaming data.
  42  *
  43  * Key parts that must be USB-specific are protocols defining how the
  44  * read/write operations relate to the hardware state machines.  There
  45  * are two types of files.  One type is for the device, implementing ep0.
  46  * The other type is for each IN or OUT endpoint.  In both cases, the
  47  * user mode driver must configure the hardware before using it.
  48  *
  49  * - First, dev_config() is called when /dev/gadget/$CHIP is configured
  50  *   (by writing configuration and device descriptors).  Afterwards it
  51  *   may serve as a source of device events, used to handle all control
  52  *   requests other than basic enumeration.
  53  *
  54  * - Then, after a SET_CONFIGURATION control request, ep_config() is
  55  *   called when each /dev/gadget/ep* file is configured (by writing
  56  *   endpoint descriptors).  Afterwards these files are used to write()
  57  *   IN data or to read() OUT data.  To halt the endpoint, a "wrong
  58  *   direction" request is issued (like reading an IN endpoint).
  59  *
  60  * Unlike "usbfs" the only ioctl()s are for things that are rare, and maybe
  61  * not possible on all hardware.  For example, precise fault handling with
  62  * respect to data left in endpoint fifos after aborted operations; or
  63  * selective clearing of endpoint halts, to implement SET_INTERFACE.
  64  */
  65 
  66 #define DRIVER_DESC     "USB Gadget filesystem"
  67 #define DRIVER_VERSION  "24 Aug 2004"
  68 
  69 static const char driver_desc [] = DRIVER_DESC;
  70 static const char shortname [] = "gadgetfs";
  71 
  72 MODULE_DESCRIPTION (DRIVER_DESC);
  73 MODULE_AUTHOR ("David Brownell");
  74 MODULE_LICENSE ("GPL");
  75 
  76 static int ep_open(struct inode *, struct file *);
  77 
  78 
  79 /*----------------------------------------------------------------------*/
  80 
  81 #define GADGETFS_MAGIC          0xaee71ee7
  82 
  83 /* /dev/gadget/$CHIP represents ep0 and the whole device */
  84 enum ep0_state {
  85         /* DISABLED is the initial state. */
  86         STATE_DEV_DISABLED = 0,
  87 
  88         /* Only one open() of /dev/gadget/$CHIP; only one file tracks
  89          * ep0/device i/o modes and binding to the controller.  Driver
  90          * must always write descriptors to initialize the device, then
  91          * the device becomes UNCONNECTED until enumeration.
  92          */
  93         STATE_DEV_OPENED,
  94 
  95         /* From then on, ep0 fd is in either of two basic modes:
  96          * - (UN)CONNECTED: read usb_gadgetfs_event(s) from it
  97          * - SETUP: read/write will transfer control data and succeed;
  98          *   or if "wrong direction", performs protocol stall
  99          */
 100         STATE_DEV_UNCONNECTED,
 101         STATE_DEV_CONNECTED,
 102         STATE_DEV_SETUP,
 103 
 104         /* UNBOUND means the driver closed ep0, so the device won't be
 105          * accessible again (DEV_DISABLED) until all fds are closed.
 106          */
 107         STATE_DEV_UNBOUND,
 108 };
 109 
 110 /* enough for the whole queue: most events invalidate others */
 111 #define N_EVENT                 5
 112 
 113 struct dev_data {
 114         spinlock_t                      lock;
 115         refcount_t                      count;
 116         int                             udc_usage;
 117         enum ep0_state                  state;          /* P: lock */
 118         struct usb_gadgetfs_event       event [N_EVENT];
 119         unsigned                        ev_next;
 120         struct fasync_struct            *fasync;
 121         u8                              current_config;
 122 
 123         /* drivers reading ep0 MUST handle control requests (SETUP)
 124          * reported that way; else the host will time out.
 125          */
 126         unsigned                        usermode_setup : 1,
 127                                         setup_in : 1,
 128                                         setup_can_stall : 1,
 129                                         setup_out_ready : 1,
 130                                         setup_out_error : 1,
 131                                         setup_abort : 1,
 132                                         gadget_registered : 1;
 133         unsigned                        setup_wLength;
 134 
 135         /* the rest is basically write-once */
 136         struct usb_config_descriptor    *config, *hs_config;
 137         struct usb_device_descriptor    *dev;
 138         struct usb_request              *req;
 139         struct usb_gadget               *gadget;
 140         struct list_head                epfiles;
 141         void                            *buf;
 142         wait_queue_head_t               wait;
 143         struct super_block              *sb;
 144         struct dentry                   *dentry;
 145 
 146         /* except this scratch i/o buffer for ep0 */
 147         u8                              rbuf [256];
 148 };
 149 
 150 static inline void get_dev (struct dev_data *data)
 151 {
 152         refcount_inc (&data->count);
 153 }
 154 
 155 static void put_dev (struct dev_data *data)
 156 {
 157         if (likely (!refcount_dec_and_test (&data->count)))
 158                 return;
 159         /* needs no more cleanup */
 160         BUG_ON (waitqueue_active (&data->wait));
 161         kfree (data);
 162 }
 163 
 164 static struct dev_data *dev_new (void)
 165 {
 166         struct dev_data         *dev;
 167 
 168         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 169         if (!dev)
 170                 return NULL;
 171         dev->state = STATE_DEV_DISABLED;
 172         refcount_set (&dev->count, 1);
 173         spin_lock_init (&dev->lock);
 174         INIT_LIST_HEAD (&dev->epfiles);
 175         init_waitqueue_head (&dev->wait);
 176         return dev;
 177 }
 178 
 179 /*----------------------------------------------------------------------*/
 180 
 181 /* other /dev/gadget/$ENDPOINT files represent endpoints */
 182 enum ep_state {
 183         STATE_EP_DISABLED = 0,
 184         STATE_EP_READY,
 185         STATE_EP_ENABLED,
 186         STATE_EP_UNBOUND,
 187 };
 188 
 189 struct ep_data {
 190         struct mutex                    lock;
 191         enum ep_state                   state;
 192         refcount_t                      count;
 193         struct dev_data                 *dev;
 194         /* must hold dev->lock before accessing ep or req */
 195         struct usb_ep                   *ep;
 196         struct usb_request              *req;
 197         ssize_t                         status;
 198         char                            name [16];
 199         struct usb_endpoint_descriptor  desc, hs_desc;
 200         struct list_head                epfiles;
 201         wait_queue_head_t               wait;
 202         struct dentry                   *dentry;
 203 };
 204 
 205 static inline void get_ep (struct ep_data *data)
 206 {
 207         refcount_inc (&data->count);
 208 }
 209 
 210 static void put_ep (struct ep_data *data)
 211 {
 212         if (likely (!refcount_dec_and_test (&data->count)))
 213                 return;
 214         put_dev (data->dev);
 215         /* needs no more cleanup */
 216         BUG_ON (!list_empty (&data->epfiles));
 217         BUG_ON (waitqueue_active (&data->wait));
 218         kfree (data);
 219 }
 220 
 221 /*----------------------------------------------------------------------*/
 222 
 223 /* most "how to use the hardware" policy choices are in userspace:
 224  * mapping endpoint roles (which the driver needs) to the capabilities
 225  * which the usb controller has.  most of those capabilities are exposed
 226  * implicitly, starting with the driver name and then endpoint names.
 227  */
 228 
 229 static const char *CHIP;
 230 
 231 /*----------------------------------------------------------------------*/
 232 
 233 /* NOTE:  don't use dev_printk calls before binding to the gadget
 234  * at the end of ep0 configuration, or after unbind.
 235  */
 236 
 237 /* too wordy: dev_printk(level , &(d)->gadget->dev , fmt , ## args) */
 238 #define xprintk(d,level,fmt,args...) \
 239         printk(level "%s: " fmt , shortname , ## args)
 240 
 241 #ifdef DEBUG
 242 #define DBG(dev,fmt,args...) \
 243         xprintk(dev , KERN_DEBUG , fmt , ## args)
 244 #else
 245 #define DBG(dev,fmt,args...) \
 246         do { } while (0)
 247 #endif /* DEBUG */
 248 
 249 #ifdef VERBOSE_DEBUG
 250 #define VDEBUG  DBG
 251 #else
 252 #define VDEBUG(dev,fmt,args...) \
 253         do { } while (0)
 254 #endif /* DEBUG */
 255 
 256 #define ERROR(dev,fmt,args...) \
 257         xprintk(dev , KERN_ERR , fmt , ## args)
 258 #define INFO(dev,fmt,args...) \
 259         xprintk(dev , KERN_INFO , fmt , ## args)
 260 
 261 
 262 /*----------------------------------------------------------------------*/
 263 
 264 /* SYNCHRONOUS ENDPOINT OPERATIONS (bulk/intr/iso)
 265  *
 266  * After opening, configure non-control endpoints.  Then use normal
 267  * stream read() and write() requests; and maybe ioctl() to get more
 268  * precise FIFO status when recovering from cancellation.
 269  */
 270 
 271 static void epio_complete (struct usb_ep *ep, struct usb_request *req)
 272 {
 273         struct ep_data  *epdata = ep->driver_data;
 274 
 275         if (!req->context)
 276                 return;
 277         if (req->status)
 278                 epdata->status = req->status;
 279         else
 280                 epdata->status = req->actual;
 281         complete ((struct completion *)req->context);
 282 }
 283 
 284 /* tasklock endpoint, returning when it's connected.
 285  * still need dev->lock to use epdata->ep.
 286  */
 287 static int
 288 get_ready_ep (unsigned f_flags, struct ep_data *epdata, bool is_write)
 289 {
 290         int     val;
 291 
 292         if (f_flags & O_NONBLOCK) {
 293                 if (!mutex_trylock(&epdata->lock))
 294                         goto nonblock;
 295                 if (epdata->state != STATE_EP_ENABLED &&
 296                     (!is_write || epdata->state != STATE_EP_READY)) {
 297                         mutex_unlock(&epdata->lock);
 298 nonblock:
 299                         val = -EAGAIN;
 300                 } else
 301                         val = 0;
 302                 return val;
 303         }
 304 
 305         val = mutex_lock_interruptible(&epdata->lock);
 306         if (val < 0)
 307                 return val;
 308 
 309         switch (epdata->state) {
 310         case STATE_EP_ENABLED:
 311                 return 0;
 312         case STATE_EP_READY:                    /* not configured yet */
 313                 if (is_write)
 314                         return 0;
 315                 // FALLTHRU
 316         case STATE_EP_UNBOUND:                  /* clean disconnect */
 317                 break;
 318         // case STATE_EP_DISABLED:              /* "can't happen" */
 319         default:                                /* error! */
 320                 pr_debug ("%s: ep %p not available, state %d\n",
 321                                 shortname, epdata, epdata->state);
 322         }
 323         mutex_unlock(&epdata->lock);
 324         return -ENODEV;
 325 }
 326 
 327 static ssize_t
 328 ep_io (struct ep_data *epdata, void *buf, unsigned len)
 329 {
 330         DECLARE_COMPLETION_ONSTACK (done);
 331         int value;
 332 
 333         spin_lock_irq (&epdata->dev->lock);
 334         if (likely (epdata->ep != NULL)) {
 335                 struct usb_request      *req = epdata->req;
 336 
 337                 req->context = &done;
 338                 req->complete = epio_complete;
 339                 req->buf = buf;
 340                 req->length = len;
 341                 value = usb_ep_queue (epdata->ep, req, GFP_ATOMIC);
 342         } else
 343                 value = -ENODEV;
 344         spin_unlock_irq (&epdata->dev->lock);
 345 
 346         if (likely (value == 0)) {
 347                 value = wait_event_interruptible (done.wait, done.done);
 348                 if (value != 0) {
 349                         spin_lock_irq (&epdata->dev->lock);
 350                         if (likely (epdata->ep != NULL)) {
 351                                 DBG (epdata->dev, "%s i/o interrupted\n",
 352                                                 epdata->name);
 353                                 usb_ep_dequeue (epdata->ep, epdata->req);
 354                                 spin_unlock_irq (&epdata->dev->lock);
 355 
 356                                 wait_event (done.wait, done.done);
 357                                 if (epdata->status == -ECONNRESET)
 358                                         epdata->status = -EINTR;
 359                         } else {
 360                                 spin_unlock_irq (&epdata->dev->lock);
 361 
 362                                 DBG (epdata->dev, "endpoint gone\n");
 363                                 epdata->status = -ENODEV;
 364                         }
 365                 }
 366                 return epdata->status;
 367         }
 368         return value;
 369 }
 370 
 371 static int
 372 ep_release (struct inode *inode, struct file *fd)
 373 {
 374         struct ep_data          *data = fd->private_data;
 375         int value;
 376 
 377         value = mutex_lock_interruptible(&data->lock);
 378         if (value < 0)
 379                 return value;
 380 
 381         /* clean up if this can be reopened */
 382         if (data->state != STATE_EP_UNBOUND) {
 383                 data->state = STATE_EP_DISABLED;
 384                 data->desc.bDescriptorType = 0;
 385                 data->hs_desc.bDescriptorType = 0;
 386                 usb_ep_disable(data->ep);
 387         }
 388         mutex_unlock(&data->lock);
 389         put_ep (data);
 390         return 0;
 391 }
 392 
 393 static long ep_ioctl(struct file *fd, unsigned code, unsigned long value)
 394 {
 395         struct ep_data          *data = fd->private_data;
 396         int                     status;
 397 
 398         if ((status = get_ready_ep (fd->f_flags, data, false)) < 0)
 399                 return status;
 400 
 401         spin_lock_irq (&data->dev->lock);
 402         if (likely (data->ep != NULL)) {
 403                 switch (code) {
 404                 case GADGETFS_FIFO_STATUS:
 405                         status = usb_ep_fifo_status (data->ep);
 406                         break;
 407                 case GADGETFS_FIFO_FLUSH:
 408                         usb_ep_fifo_flush (data->ep);
 409                         break;
 410                 case GADGETFS_CLEAR_HALT:
 411                         status = usb_ep_clear_halt (data->ep);
 412                         break;
 413                 default:
 414                         status = -ENOTTY;
 415                 }
 416         } else
 417                 status = -ENODEV;
 418         spin_unlock_irq (&data->dev->lock);
 419         mutex_unlock(&data->lock);
 420         return status;
 421 }
 422 
 423 /*----------------------------------------------------------------------*/
 424 
 425 /* ASYNCHRONOUS ENDPOINT I/O OPERATIONS (bulk/intr/iso) */
 426 
 427 struct kiocb_priv {
 428         struct usb_request      *req;
 429         struct ep_data          *epdata;
 430         struct kiocb            *iocb;
 431         struct mm_struct        *mm;
 432         struct work_struct      work;
 433         void                    *buf;
 434         struct iov_iter         to;
 435         const void              *to_free;
 436         unsigned                actual;
 437 };
 438 
 439 static int ep_aio_cancel(struct kiocb *iocb)
 440 {
 441         struct kiocb_priv       *priv = iocb->private;
 442         struct ep_data          *epdata;
 443         int                     value;
 444 
 445         local_irq_disable();
 446         epdata = priv->epdata;
 447         // spin_lock(&epdata->dev->lock);
 448         if (likely(epdata && epdata->ep && priv->req))
 449                 value = usb_ep_dequeue (epdata->ep, priv->req);
 450         else
 451                 value = -EINVAL;
 452         // spin_unlock(&epdata->dev->lock);
 453         local_irq_enable();
 454 
 455         return value;
 456 }
 457 
 458 static void ep_user_copy_worker(struct work_struct *work)
 459 {
 460         struct kiocb_priv *priv = container_of(work, struct kiocb_priv, work);
 461         struct mm_struct *mm = priv->mm;
 462         struct kiocb *iocb = priv->iocb;
 463         size_t ret;
 464 
 465         use_mm(mm);
 466         ret = copy_to_iter(priv->buf, priv->actual, &priv->to);
 467         unuse_mm(mm);
 468         if (!ret)
 469                 ret = -EFAULT;
 470 
 471         /* completing the iocb can drop the ctx and mm, don't touch mm after */
 472         iocb->ki_complete(iocb, ret, ret);
 473 
 474         kfree(priv->buf);
 475         kfree(priv->to_free);
 476         kfree(priv);
 477 }
 478 
 479 static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
 480 {
 481         struct kiocb            *iocb = req->context;
 482         struct kiocb_priv       *priv = iocb->private;
 483         struct ep_data          *epdata = priv->epdata;
 484 
 485         /* lock against disconnect (and ideally, cancel) */
 486         spin_lock(&epdata->dev->lock);
 487         priv->req = NULL;
 488         priv->epdata = NULL;
 489 
 490         /* if this was a write or a read returning no data then we
 491          * don't need to copy anything to userspace, so we can
 492          * complete the aio request immediately.
 493          */
 494         if (priv->to_free == NULL || unlikely(req->actual == 0)) {
 495                 kfree(req->buf);
 496                 kfree(priv->to_free);
 497                 kfree(priv);
 498                 iocb->private = NULL;
 499                 /* aio_complete() reports bytes-transferred _and_ faults */
 500 
 501                 iocb->ki_complete(iocb, req->actual ? req->actual : req->status,
 502                                 req->status);
 503         } else {
 504                 /* ep_copy_to_user() won't report both; we hide some faults */
 505                 if (unlikely(0 != req->status))
 506                         DBG(epdata->dev, "%s fault %d len %d\n",
 507                                 ep->name, req->status, req->actual);
 508 
 509                 priv->buf = req->buf;
 510                 priv->actual = req->actual;
 511                 INIT_WORK(&priv->work, ep_user_copy_worker);
 512                 schedule_work(&priv->work);
 513         }
 514 
 515         usb_ep_free_request(ep, req);
 516         spin_unlock(&epdata->dev->lock);
 517         put_ep(epdata);
 518 }
 519 
 520 static ssize_t ep_aio(struct kiocb *iocb,
 521                       struct kiocb_priv *priv,
 522                       struct ep_data *epdata,
 523                       char *buf,
 524                       size_t len)
 525 {
 526         struct usb_request *req;
 527         ssize_t value;
 528 
 529         iocb->private = priv;
 530         priv->iocb = iocb;
 531 
 532         kiocb_set_cancel_fn(iocb, ep_aio_cancel);
 533         get_ep(epdata);
 534         priv->epdata = epdata;
 535         priv->actual = 0;
 536         priv->mm = current->mm; /* mm teardown waits for iocbs in exit_aio() */
 537 
 538         /* each kiocb is coupled to one usb_request, but we can't
 539          * allocate or submit those if the host disconnected.
 540          */
 541         spin_lock_irq(&epdata->dev->lock);
 542         value = -ENODEV;
 543         if (unlikely(epdata->ep == NULL))
 544                 goto fail;
 545 
 546         req = usb_ep_alloc_request(epdata->ep, GFP_ATOMIC);
 547         value = -ENOMEM;
 548         if (unlikely(!req))
 549                 goto fail;
 550 
 551         priv->req = req;
 552         req->buf = buf;
 553         req->length = len;
 554         req->complete = ep_aio_complete;
 555         req->context = iocb;
 556         value = usb_ep_queue(epdata->ep, req, GFP_ATOMIC);
 557         if (unlikely(0 != value)) {
 558                 usb_ep_free_request(epdata->ep, req);
 559                 goto fail;
 560         }
 561         spin_unlock_irq(&epdata->dev->lock);
 562         return -EIOCBQUEUED;
 563 
 564 fail:
 565         spin_unlock_irq(&epdata->dev->lock);
 566         kfree(priv->to_free);
 567         kfree(priv);
 568         put_ep(epdata);
 569         return value;
 570 }
 571 
 572 static ssize_t
 573 ep_read_iter(struct kiocb *iocb, struct iov_iter *to)
 574 {
 575         struct file *file = iocb->ki_filp;
 576         struct ep_data *epdata = file->private_data;
 577         size_t len = iov_iter_count(to);
 578         ssize_t value;
 579         char *buf;
 580 
 581         if ((value = get_ready_ep(file->f_flags, epdata, false)) < 0)
 582                 return value;
 583 
 584         /* halt any endpoint by doing a "wrong direction" i/o call */
 585         if (usb_endpoint_dir_in(&epdata->desc)) {
 586                 if (usb_endpoint_xfer_isoc(&epdata->desc) ||
 587                     !is_sync_kiocb(iocb)) {
 588                         mutex_unlock(&epdata->lock);
 589                         return -EINVAL;
 590                 }
 591                 DBG (epdata->dev, "%s halt\n", epdata->name);
 592                 spin_lock_irq(&epdata->dev->lock);
 593                 if (likely(epdata->ep != NULL))
 594                         usb_ep_set_halt(epdata->ep);
 595                 spin_unlock_irq(&epdata->dev->lock);
 596                 mutex_unlock(&epdata->lock);
 597                 return -EBADMSG;
 598         }
 599 
 600         buf = kmalloc(len, GFP_KERNEL);
 601         if (unlikely(!buf)) {
 602                 mutex_unlock(&epdata->lock);
 603                 return -ENOMEM;
 604         }
 605         if (is_sync_kiocb(iocb)) {
 606                 value = ep_io(epdata, buf, len);
 607                 if (value >= 0 && (copy_to_iter(buf, value, to) != value))
 608                         value = -EFAULT;
 609         } else {
 610                 struct kiocb_priv *priv = kzalloc(sizeof *priv, GFP_KERNEL);
 611                 value = -ENOMEM;
 612                 if (!priv)
 613                         goto fail;
 614                 priv->to_free = dup_iter(&priv->to, to, GFP_KERNEL);
 615                 if (!priv->to_free) {
 616                         kfree(priv);
 617                         goto fail;
 618                 }
 619                 value = ep_aio(iocb, priv, epdata, buf, len);
 620                 if (value == -EIOCBQUEUED)
 621                         buf = NULL;
 622         }
 623 fail:
 624         kfree(buf);
 625         mutex_unlock(&epdata->lock);
 626         return value;
 627 }
 628 
 629 static ssize_t ep_config(struct ep_data *, const char *, size_t);
 630 
 631 static ssize_t
 632 ep_write_iter(struct kiocb *iocb, struct iov_iter *from)
 633 {
 634         struct file *file = iocb->ki_filp;
 635         struct ep_data *epdata = file->private_data;
 636         size_t len = iov_iter_count(from);
 637         bool configured;
 638         ssize_t value;
 639         char *buf;
 640 
 641         if ((value = get_ready_ep(file->f_flags, epdata, true)) < 0)
 642                 return value;
 643 
 644         configured = epdata->state == STATE_EP_ENABLED;
 645 
 646         /* halt any endpoint by doing a "wrong direction" i/o call */
 647         if (configured && !usb_endpoint_dir_in(&epdata->desc)) {
 648                 if (usb_endpoint_xfer_isoc(&epdata->desc) ||
 649                     !is_sync_kiocb(iocb)) {
 650                         mutex_unlock(&epdata->lock);
 651                         return -EINVAL;
 652                 }
 653                 DBG (epdata->dev, "%s halt\n", epdata->name);
 654                 spin_lock_irq(&epdata->dev->lock);
 655                 if (likely(epdata->ep != NULL))
 656                         usb_ep_set_halt(epdata->ep);
 657                 spin_unlock_irq(&epdata->dev->lock);
 658                 mutex_unlock(&epdata->lock);
 659                 return -EBADMSG;
 660         }
 661 
 662         buf = kmalloc(len, GFP_KERNEL);
 663         if (unlikely(!buf)) {
 664                 mutex_unlock(&epdata->lock);
 665                 return -ENOMEM;
 666         }
 667 
 668         if (unlikely(!copy_from_iter_full(buf, len, from))) {
 669                 value = -EFAULT;
 670                 goto out;
 671         }
 672 
 673         if (unlikely(!configured)) {
 674                 value = ep_config(epdata, buf, len);
 675         } else if (is_sync_kiocb(iocb)) {
 676                 value = ep_io(epdata, buf, len);
 677         } else {
 678                 struct kiocb_priv *priv = kzalloc(sizeof *priv, GFP_KERNEL);
 679                 value = -ENOMEM;
 680                 if (priv) {
 681                         value = ep_aio(iocb, priv, epdata, buf, len);
 682                         if (value == -EIOCBQUEUED)
 683                                 buf = NULL;
 684                 }
 685         }
 686 out:
 687         kfree(buf);
 688         mutex_unlock(&epdata->lock);
 689         return value;
 690 }
 691 
 692 /*----------------------------------------------------------------------*/
 693 
 694 /* used after endpoint configuration */
 695 static const struct file_operations ep_io_operations = {
 696         .owner =        THIS_MODULE,
 697 
 698         .open =         ep_open,
 699         .release =      ep_release,
 700         .llseek =       no_llseek,
 701         .unlocked_ioctl = ep_ioctl,
 702         .read_iter =    ep_read_iter,
 703         .write_iter =   ep_write_iter,
 704 };
 705 
 706 /* ENDPOINT INITIALIZATION
 707  *
 708  *     fd = open ("/dev/gadget/$ENDPOINT", O_RDWR)
 709  *     status = write (fd, descriptors, sizeof descriptors)
 710  *
 711  * That write establishes the endpoint configuration, configuring
 712  * the controller to process bulk, interrupt, or isochronous transfers
 713  * at the right maxpacket size, and so on.
 714  *
 715  * The descriptors are message type 1, identified by a host order u32
 716  * at the beginning of what's written.  Descriptor order is: full/low
 717  * speed descriptor, then optional high speed descriptor.
 718  */
 719 static ssize_t
 720 ep_config (struct ep_data *data, const char *buf, size_t len)
 721 {
 722         struct usb_ep           *ep;
 723         u32                     tag;
 724         int                     value, length = len;
 725 
 726         if (data->state != STATE_EP_READY) {
 727                 value = -EL2HLT;
 728                 goto fail;
 729         }
 730 
 731         value = len;
 732         if (len < USB_DT_ENDPOINT_SIZE + 4)
 733                 goto fail0;
 734 
 735         /* we might need to change message format someday */
 736         memcpy(&tag, buf, 4);
 737         if (tag != 1) {
 738                 DBG(data->dev, "config %s, bad tag %d\n", data->name, tag);
 739                 goto fail0;
 740         }
 741         buf += 4;
 742         len -= 4;
 743 
 744         /* NOTE:  audio endpoint extensions not accepted here;
 745          * just don't include the extra bytes.
 746          */
 747 
 748         /* full/low speed descriptor, then high speed */
 749         memcpy(&data->desc, buf, USB_DT_ENDPOINT_SIZE);
 750         if (data->desc.bLength != USB_DT_ENDPOINT_SIZE
 751                         || data->desc.bDescriptorType != USB_DT_ENDPOINT)
 752                 goto fail0;
 753         if (len != USB_DT_ENDPOINT_SIZE) {
 754                 if (len != 2 * USB_DT_ENDPOINT_SIZE)
 755                         goto fail0;
 756                 memcpy(&data->hs_desc, buf + USB_DT_ENDPOINT_SIZE,
 757                         USB_DT_ENDPOINT_SIZE);
 758                 if (data->hs_desc.bLength != USB_DT_ENDPOINT_SIZE
 759                                 || data->hs_desc.bDescriptorType
 760                                         != USB_DT_ENDPOINT) {
 761                         DBG(data->dev, "config %s, bad hs length or type\n",
 762                                         data->name);
 763                         goto fail0;
 764                 }
 765         }
 766 
 767         spin_lock_irq (&data->dev->lock);
 768         if (data->dev->state == STATE_DEV_UNBOUND) {
 769                 value = -ENOENT;
 770                 goto gone;
 771         } else {
 772                 ep = data->ep;
 773                 if (ep == NULL) {
 774                         value = -ENODEV;
 775                         goto gone;
 776                 }
 777         }
 778         switch (data->dev->gadget->speed) {
 779         case USB_SPEED_LOW:
 780         case USB_SPEED_FULL:
 781                 ep->desc = &data->desc;
 782                 break;
 783         case USB_SPEED_HIGH:
 784                 /* fails if caller didn't provide that descriptor... */
 785                 ep->desc = &data->hs_desc;
 786                 break;
 787         default:
 788                 DBG(data->dev, "unconnected, %s init abandoned\n",
 789                                 data->name);
 790                 value = -EINVAL;
 791                 goto gone;
 792         }
 793         value = usb_ep_enable(ep);
 794         if (value == 0) {
 795                 data->state = STATE_EP_ENABLED;
 796                 value = length;
 797         }
 798 gone:
 799         spin_unlock_irq (&data->dev->lock);
 800         if (value < 0) {
 801 fail:
 802                 data->desc.bDescriptorType = 0;
 803                 data->hs_desc.bDescriptorType = 0;
 804         }
 805         return value;
 806 fail0:
 807         value = -EINVAL;
 808         goto fail;
 809 }
 810 
 811 static int
 812 ep_open (struct inode *inode, struct file *fd)
 813 {
 814         struct ep_data          *data = inode->i_private;
 815         int                     value = -EBUSY;
 816 
 817         if (mutex_lock_interruptible(&data->lock) != 0)
 818                 return -EINTR;
 819         spin_lock_irq (&data->dev->lock);
 820         if (data->dev->state == STATE_DEV_UNBOUND)
 821                 value = -ENOENT;
 822         else if (data->state == STATE_EP_DISABLED) {
 823                 value = 0;
 824                 data->state = STATE_EP_READY;
 825                 get_ep (data);
 826                 fd->private_data = data;
 827                 VDEBUG (data->dev, "%s ready\n", data->name);
 828         } else
 829                 DBG (data->dev, "%s state %d\n",
 830                         data->name, data->state);
 831         spin_unlock_irq (&data->dev->lock);
 832         mutex_unlock(&data->lock);
 833         return value;
 834 }
 835 
 836 /*----------------------------------------------------------------------*/
 837 
 838 /* EP0 IMPLEMENTATION can be partly in userspace.
 839  *
 840  * Drivers that use this facility receive various events, including
 841  * control requests the kernel doesn't handle.  Drivers that don't
 842  * use this facility may be too simple-minded for real applications.
 843  */
 844 
 845 static inline void ep0_readable (struct dev_data *dev)
 846 {
 847         wake_up (&dev->wait);
 848         kill_fasync (&dev->fasync, SIGIO, POLL_IN);
 849 }
 850 
 851 static void clean_req (struct usb_ep *ep, struct usb_request *req)
 852 {
 853         struct dev_data         *dev = ep->driver_data;
 854 
 855         if (req->buf != dev->rbuf) {
 856                 kfree(req->buf);
 857                 req->buf = dev->rbuf;
 858         }
 859         req->complete = epio_complete;
 860         dev->setup_out_ready = 0;
 861 }
 862 
 863 static void ep0_complete (struct usb_ep *ep, struct usb_request *req)
 864 {
 865         struct dev_data         *dev = ep->driver_data;
 866         unsigned long           flags;
 867         int                     free = 1;
 868 
 869         /* for control OUT, data must still get to userspace */
 870         spin_lock_irqsave(&dev->lock, flags);
 871         if (!dev->setup_in) {
 872                 dev->setup_out_error = (req->status != 0);
 873                 if (!dev->setup_out_error)
 874                         free = 0;
 875                 dev->setup_out_ready = 1;
 876                 ep0_readable (dev);
 877         }
 878 
 879         /* clean up as appropriate */
 880         if (free && req->buf != &dev->rbuf)
 881                 clean_req (ep, req);
 882         req->complete = epio_complete;
 883         spin_unlock_irqrestore(&dev->lock, flags);
 884 }
 885 
 886 static int setup_req (struct usb_ep *ep, struct usb_request *req, u16 len)
 887 {
 888         struct dev_data *dev = ep->driver_data;
 889 
 890         if (dev->setup_out_ready) {
 891                 DBG (dev, "ep0 request busy!\n");
 892                 return -EBUSY;
 893         }
 894         if (len > sizeof (dev->rbuf))
 895                 req->buf = kmalloc(len, GFP_ATOMIC);
 896         if (req->buf == NULL) {
 897                 req->buf = dev->rbuf;
 898                 return -ENOMEM;
 899         }
 900         req->complete = ep0_complete;
 901         req->length = len;
 902         req->zero = 0;
 903         return 0;
 904 }
 905 
 906 static ssize_t
 907 ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
 908 {
 909         struct dev_data                 *dev = fd->private_data;
 910         ssize_t                         retval;
 911         enum ep0_state                  state;
 912 
 913         spin_lock_irq (&dev->lock);
 914         if (dev->state <= STATE_DEV_OPENED) {
 915                 retval = -EINVAL;
 916                 goto done;
 917         }
 918 
 919         /* report fd mode change before acting on it */
 920         if (dev->setup_abort) {
 921                 dev->setup_abort = 0;
 922                 retval = -EIDRM;
 923                 goto done;
 924         }
 925 
 926         /* control DATA stage */
 927         if ((state = dev->state) == STATE_DEV_SETUP) {
 928 
 929                 if (dev->setup_in) {            /* stall IN */
 930                         VDEBUG(dev, "ep0in stall\n");
 931                         (void) usb_ep_set_halt (dev->gadget->ep0);
 932                         retval = -EL2HLT;
 933                         dev->state = STATE_DEV_CONNECTED;
 934 
 935                 } else if (len == 0) {          /* ack SET_CONFIGURATION etc */
 936                         struct usb_ep           *ep = dev->gadget->ep0;
 937                         struct usb_request      *req = dev->req;
 938 
 939                         if ((retval = setup_req (ep, req, 0)) == 0) {
 940                                 ++dev->udc_usage;
 941                                 spin_unlock_irq (&dev->lock);
 942                                 retval = usb_ep_queue (ep, req, GFP_KERNEL);
 943                                 spin_lock_irq (&dev->lock);
 944                                 --dev->udc_usage;
 945                         }
 946                         dev->state = STATE_DEV_CONNECTED;
 947 
 948                         /* assume that was SET_CONFIGURATION */
 949                         if (dev->current_config) {
 950                                 unsigned power;
 951 
 952                                 if (gadget_is_dualspeed(dev->gadget)
 953                                                 && (dev->gadget->speed
 954                                                         == USB_SPEED_HIGH))
 955                                         power = dev->hs_config->bMaxPower;
 956                                 else
 957                                         power = dev->config->bMaxPower;
 958                                 usb_gadget_vbus_draw(dev->gadget, 2 * power);
 959                         }
 960 
 961                 } else {                        /* collect OUT data */
 962                         if ((fd->f_flags & O_NONBLOCK) != 0
 963                                         && !dev->setup_out_ready) {
 964                                 retval = -EAGAIN;
 965                                 goto done;
 966                         }
 967                         spin_unlock_irq (&dev->lock);
 968                         retval = wait_event_interruptible (dev->wait,
 969                                         dev->setup_out_ready != 0);
 970 
 971                         /* FIXME state could change from under us */
 972                         spin_lock_irq (&dev->lock);
 973                         if (retval)
 974                                 goto done;
 975 
 976                         if (dev->state != STATE_DEV_SETUP) {
 977                                 retval = -ECANCELED;
 978                                 goto done;
 979                         }
 980                         dev->state = STATE_DEV_CONNECTED;
 981 
 982                         if (dev->setup_out_error)
 983                                 retval = -EIO;
 984                         else {
 985                                 len = min (len, (size_t)dev->req->actual);
 986                                 ++dev->udc_usage;
 987                                 spin_unlock_irq(&dev->lock);
 988                                 if (copy_to_user (buf, dev->req->buf, len))
 989                                         retval = -EFAULT;
 990                                 else
 991                                         retval = len;
 992                                 spin_lock_irq(&dev->lock);
 993                                 --dev->udc_usage;
 994                                 clean_req (dev->gadget->ep0, dev->req);
 995                                 /* NOTE userspace can't yet choose to stall */
 996                         }
 997                 }
 998                 goto done;
 999         }
1000 
1001         /* else normal: return event data */
1002         if (len < sizeof dev->event [0]) {
1003                 retval = -EINVAL;
1004                 goto done;
1005         }
1006         len -= len % sizeof (struct usb_gadgetfs_event);
1007         dev->usermode_setup = 1;
1008 
1009 scan:
1010         /* return queued events right away */
1011         if (dev->ev_next != 0) {
1012                 unsigned                i, n;
1013 
1014                 n = len / sizeof (struct usb_gadgetfs_event);
1015                 if (dev->ev_next < n)
1016                         n = dev->ev_next;
1017 
1018                 /* ep0 i/o has special semantics during STATE_DEV_SETUP */
1019                 for (i = 0; i < n; i++) {
1020                         if (dev->event [i].type == GADGETFS_SETUP) {
1021                                 dev->state = STATE_DEV_SETUP;
1022                                 n = i + 1;
1023                                 break;
1024                         }
1025                 }
1026                 spin_unlock_irq (&dev->lock);
1027                 len = n * sizeof (struct usb_gadgetfs_event);
1028                 if (copy_to_user (buf, &dev->event, len))
1029                         retval = -EFAULT;
1030                 else
1031                         retval = len;
1032                 if (len > 0) {
1033                         /* NOTE this doesn't guard against broken drivers;
1034                          * concurrent ep0 readers may lose events.
1035                          */
1036                         spin_lock_irq (&dev->lock);
1037                         if (dev->ev_next > n) {
1038                                 memmove(&dev->event[0], &dev->event[n],
1039                                         sizeof (struct usb_gadgetfs_event)
1040                                                 * (dev->ev_next - n));
1041                         }
1042                         dev->ev_next -= n;
1043                         spin_unlock_irq (&dev->lock);
1044                 }
1045                 return retval;
1046         }
1047         if (fd->f_flags & O_NONBLOCK) {
1048                 retval = -EAGAIN;
1049                 goto done;
1050         }
1051 
1052         switch (state) {
1053         default:
1054                 DBG (dev, "fail %s, state %d\n", __func__, state);
1055                 retval = -ESRCH;
1056                 break;
1057         case STATE_DEV_UNCONNECTED:
1058         case STATE_DEV_CONNECTED:
1059                 spin_unlock_irq (&dev->lock);
1060                 DBG (dev, "%s wait\n", __func__);
1061 
1062                 /* wait for events */
1063                 retval = wait_event_interruptible (dev->wait,
1064                                 dev->ev_next != 0);
1065                 if (retval < 0)
1066                         return retval;
1067                 spin_lock_irq (&dev->lock);
1068                 goto scan;
1069         }
1070 
1071 done:
1072         spin_unlock_irq (&dev->lock);
1073         return retval;
1074 }
1075 
1076 static struct usb_gadgetfs_event *
1077 next_event (struct dev_data *dev, enum usb_gadgetfs_event_type type)
1078 {
1079         struct usb_gadgetfs_event       *event;
1080         unsigned                        i;
1081 
1082         switch (type) {
1083         /* these events purge the queue */
1084         case GADGETFS_DISCONNECT:
1085                 if (dev->state == STATE_DEV_SETUP)
1086                         dev->setup_abort = 1;
1087                 // FALL THROUGH
1088         case GADGETFS_CONNECT:
1089                 dev->ev_next = 0;
1090                 break;
1091         case GADGETFS_SETUP:            /* previous request timed out */
1092         case GADGETFS_SUSPEND:          /* same effect */
1093                 /* these events can't be repeated */
1094                 for (i = 0; i != dev->ev_next; i++) {
1095                         if (dev->event [i].type != type)
1096                                 continue;
1097                         DBG(dev, "discard old event[%d] %d\n", i, type);
1098                         dev->ev_next--;
1099                         if (i == dev->ev_next)
1100                                 break;
1101                         /* indices start at zero, for simplicity */
1102                         memmove (&dev->event [i], &dev->event [i + 1],
1103                                 sizeof (struct usb_gadgetfs_event)
1104                                         * (dev->ev_next - i));
1105                 }
1106                 break;
1107         default:
1108                 BUG ();
1109         }
1110         VDEBUG(dev, "event[%d] = %d\n", dev->ev_next, type);
1111         event = &dev->event [dev->ev_next++];
1112         BUG_ON (dev->ev_next > N_EVENT);
1113         memset (event, 0, sizeof *event);
1114         event->type = type;
1115         return event;
1116 }
1117 
1118 static ssize_t
1119 ep0_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
1120 {
1121         struct dev_data         *dev = fd->private_data;
1122         ssize_t                 retval = -ESRCH;
1123 
1124         /* report fd mode change before acting on it */
1125         if (dev->setup_abort) {
1126                 dev->setup_abort = 0;
1127                 retval = -EIDRM;
1128 
1129         /* data and/or status stage for control request */
1130         } else if (dev->state == STATE_DEV_SETUP) {
1131 
1132                 len = min_t(size_t, len, dev->setup_wLength);
1133                 if (dev->setup_in) {
1134                         retval = setup_req (dev->gadget->ep0, dev->req, len);
1135                         if (retval == 0) {
1136                                 dev->state = STATE_DEV_CONNECTED;
1137                                 ++dev->udc_usage;
1138                                 spin_unlock_irq (&dev->lock);
1139                                 if (copy_from_user (dev->req->buf, buf, len))
1140                                         retval = -EFAULT;
1141                                 else {
1142                                         if (len < dev->setup_wLength)
1143                                                 dev->req->zero = 1;
1144                                         retval = usb_ep_queue (
1145                                                 dev->gadget->ep0, dev->req,
1146                                                 GFP_KERNEL);
1147                                 }
1148                                 spin_lock_irq(&dev->lock);
1149                                 --dev->udc_usage;
1150                                 if (retval < 0) {
1151                                         clean_req (dev->gadget->ep0, dev->req);
1152                                 } else
1153                                         retval = len;
1154 
1155                                 return retval;
1156                         }
1157 
1158                 /* can stall some OUT transfers */
1159                 } else if (dev->setup_can_stall) {
1160                         VDEBUG(dev, "ep0out stall\n");
1161                         (void) usb_ep_set_halt (dev->gadget->ep0);
1162                         retval = -EL2HLT;
1163                         dev->state = STATE_DEV_CONNECTED;
1164                 } else {
1165                         DBG(dev, "bogus ep0out stall!\n");
1166                 }
1167         } else
1168                 DBG (dev, "fail %s, state %d\n", __func__, dev->state);
1169 
1170         return retval;
1171 }
1172 
1173 static int
1174 ep0_fasync (int f, struct file *fd, int on)
1175 {
1176         struct dev_data         *dev = fd->private_data;
1177         // caller must F_SETOWN before signal delivery happens
1178         VDEBUG (dev, "%s %s\n", __func__, on ? "on" : "off");
1179         return fasync_helper (f, fd, on, &dev->fasync);
1180 }
1181 
1182 static struct usb_gadget_driver gadgetfs_driver;
1183 
1184 static int
1185 dev_release (struct inode *inode, struct file *fd)
1186 {
1187         struct dev_data         *dev = fd->private_data;
1188 
1189         /* closing ep0 === shutdown all */
1190 
1191         if (dev->gadget_registered) {
1192                 usb_gadget_unregister_driver (&gadgetfs_driver);
1193                 dev->gadget_registered = false;
1194         }
1195 
1196         /* at this point "good" hardware has disconnected the
1197          * device from USB; the host won't see it any more.
1198          * alternatively, all host requests will time out.
1199          */
1200 
1201         kfree (dev->buf);
1202         dev->buf = NULL;
1203 
1204         /* other endpoints were all decoupled from this device */
1205         spin_lock_irq(&dev->lock);
1206         dev->state = STATE_DEV_DISABLED;
1207         spin_unlock_irq(&dev->lock);
1208 
1209         put_dev (dev);
1210         return 0;
1211 }
1212 
1213 static __poll_t
1214 ep0_poll (struct file *fd, poll_table *wait)
1215 {
1216        struct dev_data         *dev = fd->private_data;
1217        __poll_t                mask = 0;
1218 
1219         if (dev->state <= STATE_DEV_OPENED)
1220                 return DEFAULT_POLLMASK;
1221 
1222         poll_wait(fd, &dev->wait, wait);
1223 
1224         spin_lock_irq(&dev->lock);
1225 
1226         /* report fd mode change before acting on it */
1227         if (dev->setup_abort) {
1228                 dev->setup_abort = 0;
1229                 mask = EPOLLHUP;
1230                 goto out;
1231         }
1232 
1233         if (dev->state == STATE_DEV_SETUP) {
1234                 if (dev->setup_in || dev->setup_can_stall)
1235                         mask = EPOLLOUT;
1236         } else {
1237                 if (dev->ev_next != 0)
1238                         mask = EPOLLIN;
1239         }
1240 out:
1241         spin_unlock_irq(&dev->lock);
1242         return mask;
1243 }
1244 
1245 static long dev_ioctl (struct file *fd, unsigned code, unsigned long value)
1246 {
1247         struct dev_data         *dev = fd->private_data;
1248         struct usb_gadget       *gadget = dev->gadget;
1249         long ret = -ENOTTY;
1250 
1251         spin_lock_irq(&dev->lock);
1252         if (dev->state == STATE_DEV_OPENED ||
1253                         dev->state == STATE_DEV_UNBOUND) {
1254                 /* Not bound to a UDC */
1255         } else if (gadget->ops->ioctl) {
1256                 ++dev->udc_usage;
1257                 spin_unlock_irq(&dev->lock);
1258 
1259                 ret = gadget->ops->ioctl (gadget, code, value);
1260 
1261                 spin_lock_irq(&dev->lock);
1262                 --dev->udc_usage;
1263         }
1264         spin_unlock_irq(&dev->lock);
1265 
1266         return ret;
1267 }
1268 
1269 /*----------------------------------------------------------------------*/
1270 
1271 /* The in-kernel gadget driver handles most ep0 issues, in particular
1272  * enumerating the single configuration (as provided from user space).
1273  *
1274  * Unrecognized ep0 requests may be handled in user space.
1275  */
1276 
1277 static void make_qualifier (struct dev_data *dev)
1278 {
1279         struct usb_qualifier_descriptor         qual;
1280         struct usb_device_descriptor            *desc;
1281 
1282         qual.bLength = sizeof qual;
1283         qual.bDescriptorType = USB_DT_DEVICE_QUALIFIER;
1284         qual.bcdUSB = cpu_to_le16 (0x0200);
1285 
1286         desc = dev->dev;
1287         qual.bDeviceClass = desc->bDeviceClass;
1288         qual.bDeviceSubClass = desc->bDeviceSubClass;
1289         qual.bDeviceProtocol = desc->bDeviceProtocol;
1290 
1291         /* assumes ep0 uses the same value for both speeds ... */
1292         qual.bMaxPacketSize0 = dev->gadget->ep0->maxpacket;
1293 
1294         qual.bNumConfigurations = 1;
1295         qual.bRESERVED = 0;
1296 
1297         memcpy (dev->rbuf, &qual, sizeof qual);
1298 }
1299 
1300 static int
1301 config_buf (struct dev_data *dev, u8 type, unsigned index)
1302 {
1303         int             len;
1304         int             hs = 0;
1305 
1306         /* only one configuration */
1307         if (index > 0)
1308                 return -EINVAL;
1309 
1310         if (gadget_is_dualspeed(dev->gadget)) {
1311                 hs = (dev->gadget->speed == USB_SPEED_HIGH);
1312                 if (type == USB_DT_OTHER_SPEED_CONFIG)
1313                         hs = !hs;
1314         }
1315         if (hs) {
1316                 dev->req->buf = dev->hs_config;
1317                 len = le16_to_cpu(dev->hs_config->wTotalLength);
1318         } else {
1319                 dev->req->buf = dev->config;
1320                 len = le16_to_cpu(dev->config->wTotalLength);
1321         }
1322         ((u8 *)dev->req->buf) [1] = type;
1323         return len;
1324 }
1325 
1326 static int
1327 gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
1328 {
1329         struct dev_data                 *dev = get_gadget_data (gadget);
1330         struct usb_request              *req = dev->req;
1331         int                             value = -EOPNOTSUPP;
1332         struct usb_gadgetfs_event       *event;
1333         u16                             w_value = le16_to_cpu(ctrl->wValue);
1334         u16                             w_length = le16_to_cpu(ctrl->wLength);
1335 
1336         spin_lock (&dev->lock);
1337         dev->setup_abort = 0;
1338         if (dev->state == STATE_DEV_UNCONNECTED) {
1339                 if (gadget_is_dualspeed(gadget)
1340                                 && gadget->speed == USB_SPEED_HIGH
1341                                 && dev->hs_config == NULL) {
1342                         spin_unlock(&dev->lock);
1343                         ERROR (dev, "no high speed config??\n");
1344                         return -EINVAL;
1345                 }
1346 
1347                 dev->state = STATE_DEV_CONNECTED;
1348 
1349                 INFO (dev, "connected\n");
1350                 event = next_event (dev, GADGETFS_CONNECT);
1351                 event->u.speed = gadget->speed;
1352                 ep0_readable (dev);
1353 
1354         /* host may have given up waiting for response.  we can miss control
1355          * requests handled lower down (device/endpoint status and features);
1356          * then ep0_{read,write} will report the wrong status. controller
1357          * driver will have aborted pending i/o.
1358          */
1359         } else if (dev->state == STATE_DEV_SETUP)
1360                 dev->setup_abort = 1;
1361 
1362         req->buf = dev->rbuf;
1363         req->context = NULL;
1364         switch (ctrl->bRequest) {
1365 
1366         case USB_REQ_GET_DESCRIPTOR:
1367                 if (ctrl->bRequestType != USB_DIR_IN)
1368                         goto unrecognized;
1369                 switch (w_value >> 8) {
1370 
1371                 case USB_DT_DEVICE:
1372                         value = min (w_length, (u16) sizeof *dev->dev);
1373                         dev->dev->bMaxPacketSize0 = dev->gadget->ep0->maxpacket;
1374                         req->buf = dev->dev;
1375                         break;
1376                 case USB_DT_DEVICE_QUALIFIER:
1377                         if (!dev->hs_config)
1378                                 break;
1379                         value = min (w_length, (u16)
1380                                 sizeof (struct usb_qualifier_descriptor));
1381                         make_qualifier (dev);
1382                         break;
1383                 case USB_DT_OTHER_SPEED_CONFIG:
1384                         // FALLTHROUGH
1385                 case USB_DT_CONFIG:
1386                         value = config_buf (dev,
1387                                         w_value >> 8,
1388                                         w_value & 0xff);
1389                         if (value >= 0)
1390                                 value = min (w_length, (u16) value);
1391                         break;
1392                 case USB_DT_STRING:
1393                         goto unrecognized;
1394 
1395                 default:                // all others are errors
1396                         break;
1397                 }
1398                 break;
1399 
1400         /* currently one config, two speeds */
1401         case USB_REQ_SET_CONFIGURATION:
1402                 if (ctrl->bRequestType != 0)
1403                         goto unrecognized;
1404                 if (0 == (u8) w_value) {
1405                         value = 0;
1406                         dev->current_config = 0;
1407                         usb_gadget_vbus_draw(gadget, 8 /* mA */ );
1408                         // user mode expected to disable endpoints
1409                 } else {
1410                         u8      config, power;
1411 
1412                         if (gadget_is_dualspeed(gadget)
1413                                         && gadget->speed == USB_SPEED_HIGH) {
1414                                 config = dev->hs_config->bConfigurationValue;
1415                                 power = dev->hs_config->bMaxPower;
1416                         } else {
1417                                 config = dev->config->bConfigurationValue;
1418                                 power = dev->config->bMaxPower;
1419                         }
1420 
1421                         if (config == (u8) w_value) {
1422                                 value = 0;
1423                                 dev->current_config = config;
1424                                 usb_gadget_vbus_draw(gadget, 2 * power);
1425                         }
1426                 }
1427 
1428                 /* report SET_CONFIGURATION like any other control request,
1429                  * except that usermode may not stall this.  the next
1430                  * request mustn't be allowed start until this finishes:
1431                  * endpoints and threads set up, etc.
1432                  *
1433                  * NOTE:  older PXA hardware (before PXA 255: without UDCCFR)
1434                  * has bad/racey automagic that prevents synchronizing here.
1435                  * even kernel mode drivers often miss them.
1436                  */
1437                 if (value == 0) {
1438                         INFO (dev, "configuration #%d\n", dev->current_config);
1439                         usb_gadget_set_state(gadget, USB_STATE_CONFIGURED);
1440                         if (dev->usermode_setup) {
1441                                 dev->setup_can_stall = 0;
1442                                 goto delegate;
1443                         }
1444                 }
1445                 break;
1446 
1447 #ifndef CONFIG_USB_PXA25X
1448         /* PXA automagically handles this request too */
1449         case USB_REQ_GET_CONFIGURATION:
1450                 if (ctrl->bRequestType != 0x80)
1451                         goto unrecognized;
1452                 *(u8 *)req->buf = dev->current_config;
1453                 value = min (w_length, (u16) 1);
1454                 break;
1455 #endif
1456 
1457         default:
1458 unrecognized:
1459                 VDEBUG (dev, "%s req%02x.%02x v%04x i%04x l%d\n",
1460                         dev->usermode_setup ? "delegate" : "fail",
1461                         ctrl->bRequestType, ctrl->bRequest,
1462                         w_value, le16_to_cpu(ctrl->wIndex), w_length);
1463 
1464                 /* if there's an ep0 reader, don't stall */
1465                 if (dev->usermode_setup) {
1466                         dev->setup_can_stall = 1;
1467 delegate:
1468                         dev->setup_in = (ctrl->bRequestType & USB_DIR_IN)
1469                                                 ? 1 : 0;
1470                         dev->setup_wLength = w_length;
1471                         dev->setup_out_ready = 0;
1472                         dev->setup_out_error = 0;
1473 
1474                         /* read DATA stage for OUT right away */
1475                         if (unlikely (!dev->setup_in && w_length)) {
1476                                 value = setup_req (gadget->ep0, dev->req,
1477                                                         w_length);
1478                                 if (value < 0)
1479                                         break;
1480 
1481                                 ++dev->udc_usage;
1482                                 spin_unlock (&dev->lock);
1483                                 value = usb_ep_queue (gadget->ep0, dev->req,
1484                                                         GFP_KERNEL);
1485                                 spin_lock (&dev->lock);
1486                                 --dev->udc_usage;
1487                                 if (value < 0) {
1488                                         clean_req (gadget->ep0, dev->req);
1489                                         break;
1490                                 }
1491 
1492                                 /* we can't currently stall these */
1493                                 dev->setup_can_stall = 0;
1494                         }
1495 
1496                         /* state changes when reader collects event */
1497                         event = next_event (dev, GADGETFS_SETUP);
1498                         event->u.setup = *ctrl;
1499                         ep0_readable (dev);
1500                         spin_unlock (&dev->lock);
1501                         return 0;
1502                 }
1503         }
1504 
1505         /* proceed with data transfer and status phases? */
1506         if (value >= 0 && dev->state != STATE_DEV_SETUP) {
1507                 req->length = value;
1508                 req->zero = value < w_length;
1509 
1510                 ++dev->udc_usage;
1511                 spin_unlock (&dev->lock);
1512                 value = usb_ep_queue (gadget->ep0, req, GFP_KERNEL);
1513                 spin_lock(&dev->lock);
1514                 --dev->udc_usage;
1515                 spin_unlock(&dev->lock);
1516                 if (value < 0) {
1517                         DBG (dev, "ep_queue --> %d\n", value);
1518                         req->status = 0;
1519                 }
1520                 return value;
1521         }
1522 
1523         /* device stalls when value < 0 */
1524         spin_unlock (&dev->lock);
1525         return value;
1526 }
1527 
1528 static void destroy_ep_files (struct dev_data *dev)
1529 {
1530         DBG (dev, "%s %d\n", __func__, dev->state);
1531 
1532         /* dev->state must prevent interference */
1533         spin_lock_irq (&dev->lock);
1534         while (!list_empty(&dev->epfiles)) {
1535                 struct ep_data  *ep;
1536                 struct inode    *parent;
1537                 struct dentry   *dentry;
1538 
1539                 /* break link to FS */
1540                 ep = list_first_entry (&dev->epfiles, struct ep_data, epfiles);
1541                 list_del_init (&ep->epfiles);
1542                 spin_unlock_irq (&dev->lock);
1543 
1544                 dentry = ep->dentry;
1545                 ep->dentry = NULL;
1546                 parent = d_inode(dentry->d_parent);
1547 
1548                 /* break link to controller */
1549                 mutex_lock(&ep->lock);
1550                 if (ep->state == STATE_EP_ENABLED)
1551                         (void) usb_ep_disable (ep->ep);
1552                 ep->state = STATE_EP_UNBOUND;
1553                 usb_ep_free_request (ep->ep, ep->req);
1554                 ep->ep = NULL;
1555                 mutex_unlock(&ep->lock);
1556 
1557                 wake_up (&ep->wait);
1558                 put_ep (ep);
1559 
1560                 /* break link to dcache */
1561                 inode_lock(parent);
1562                 d_delete (dentry);
1563                 dput (dentry);
1564                 inode_unlock(parent);
1565 
1566                 spin_lock_irq (&dev->lock);
1567         }
1568         spin_unlock_irq (&dev->lock);
1569 }
1570 
1571 
1572 static struct dentry *
1573 gadgetfs_create_file (struct super_block *sb, char const *name,
1574                 void *data, const struct file_operations *fops);
1575 
1576 static int activate_ep_files (struct dev_data *dev)
1577 {
1578         struct usb_ep   *ep;
1579         struct ep_data  *data;
1580 
1581         gadget_for_each_ep (ep, dev->gadget) {
1582 
1583                 data = kzalloc(sizeof(*data), GFP_KERNEL);
1584                 if (!data)
1585                         goto enomem0;
1586                 data->state = STATE_EP_DISABLED;
1587                 mutex_init(&data->lock);
1588                 init_waitqueue_head (&data->wait);
1589 
1590                 strncpy (data->name, ep->name, sizeof (data->name) - 1);
1591                 refcount_set (&data->count, 1);
1592                 data->dev = dev;
1593                 get_dev (dev);
1594 
1595                 data->ep = ep;
1596                 ep->driver_data = data;
1597 
1598                 data->req = usb_ep_alloc_request (ep, GFP_KERNEL);
1599                 if (!data->req)
1600                         goto enomem1;
1601 
1602                 data->dentry = gadgetfs_create_file (dev->sb, data->name,
1603                                 data, &ep_io_operations);
1604                 if (!data->dentry)
1605                         goto enomem2;
1606                 list_add_tail (&data->epfiles, &dev->epfiles);
1607         }
1608         return 0;
1609 
1610 enomem2:
1611         usb_ep_free_request (ep, data->req);
1612 enomem1:
1613         put_dev (dev);
1614         kfree (data);
1615 enomem0:
1616         DBG (dev, "%s enomem\n", __func__);
1617         destroy_ep_files (dev);
1618         return -ENOMEM;
1619 }
1620 
1621 static void
1622 gadgetfs_unbind (struct usb_gadget *gadget)
1623 {
1624         struct dev_data         *dev = get_gadget_data (gadget);
1625 
1626         DBG (dev, "%s\n", __func__);
1627 
1628         spin_lock_irq (&dev->lock);
1629         dev->state = STATE_DEV_UNBOUND;
1630         while (dev->udc_usage > 0) {
1631                 spin_unlock_irq(&dev->lock);
1632                 usleep_range(1000, 2000);
1633                 spin_lock_irq(&dev->lock);
1634         }
1635         spin_unlock_irq (&dev->lock);
1636 
1637         destroy_ep_files (dev);
1638         gadget->ep0->driver_data = NULL;
1639         set_gadget_data (gadget, NULL);
1640 
1641         /* we've already been disconnected ... no i/o is active */
1642         if (dev->req)
1643                 usb_ep_free_request (gadget->ep0, dev->req);
1644         DBG (dev, "%s done\n", __func__);
1645         put_dev (dev);
1646 }
1647 
1648 static struct dev_data          *the_device;
1649 
1650 static int gadgetfs_bind(struct usb_gadget *gadget,
1651                 struct usb_gadget_driver *driver)
1652 {
1653         struct dev_data         *dev = the_device;
1654 
1655         if (!dev)
1656                 return -ESRCH;
1657         if (0 != strcmp (CHIP, gadget->name)) {
1658                 pr_err("%s expected %s controller not %s\n",
1659                         shortname, CHIP, gadget->name);
1660                 return -ENODEV;
1661         }
1662 
1663         set_gadget_data (gadget, dev);
1664         dev->gadget = gadget;
1665         gadget->ep0->driver_data = dev;
1666 
1667         /* preallocate control response and buffer */
1668         dev->req = usb_ep_alloc_request (gadget->ep0, GFP_KERNEL);
1669         if (!dev->req)
1670                 goto enomem;
1671         dev->req->context = NULL;
1672         dev->req->complete = epio_complete;
1673 
1674         if (activate_ep_files (dev) < 0)
1675                 goto enomem;
1676 
1677         INFO (dev, "bound to %s driver\n", gadget->name);
1678         spin_lock_irq(&dev->lock);
1679         dev->state = STATE_DEV_UNCONNECTED;
1680         spin_unlock_irq(&dev->lock);
1681         get_dev (dev);
1682         return 0;
1683 
1684 enomem:
1685         gadgetfs_unbind (gadget);
1686         return -ENOMEM;
1687 }
1688 
1689 static void
1690 gadgetfs_disconnect (struct usb_gadget *gadget)
1691 {
1692         struct dev_data         *dev = get_gadget_data (gadget);
1693         unsigned long           flags;
1694 
1695         spin_lock_irqsave (&dev->lock, flags);
1696         if (dev->state == STATE_DEV_UNCONNECTED)
1697                 goto exit;
1698         dev->state = STATE_DEV_UNCONNECTED;
1699 
1700         INFO (dev, "disconnected\n");
1701         next_event (dev, GADGETFS_DISCONNECT);
1702         ep0_readable (dev);
1703 exit:
1704         spin_unlock_irqrestore (&dev->lock, flags);
1705 }
1706 
1707 static void
1708 gadgetfs_suspend (struct usb_gadget *gadget)
1709 {
1710         struct dev_data         *dev = get_gadget_data (gadget);
1711         unsigned long           flags;
1712 
1713         INFO (dev, "suspended from state %d\n", dev->state);
1714         spin_lock_irqsave(&dev->lock, flags);
1715         switch (dev->state) {
1716         case STATE_DEV_SETUP:           // VERY odd... host died??
1717         case STATE_DEV_CONNECTED:
1718         case STATE_DEV_UNCONNECTED:
1719                 next_event (dev, GADGETFS_SUSPEND);
1720                 ep0_readable (dev);
1721                 /* FALLTHROUGH */
1722         default:
1723                 break;
1724         }
1725         spin_unlock_irqrestore(&dev->lock, flags);
1726 }
1727 
1728 static struct usb_gadget_driver gadgetfs_driver = {
1729         .function       = (char *) driver_desc,
1730         .bind           = gadgetfs_bind,
1731         .unbind         = gadgetfs_unbind,
1732         .setup          = gadgetfs_setup,
1733         .reset          = gadgetfs_disconnect,
1734         .disconnect     = gadgetfs_disconnect,
1735         .suspend        = gadgetfs_suspend,
1736 
1737         .driver = {
1738                 .name           = (char *) shortname,
1739         },
1740 };
1741 
1742 /*----------------------------------------------------------------------*/
1743 /* DEVICE INITIALIZATION
1744  *
1745  *     fd = open ("/dev/gadget/$CHIP", O_RDWR)
1746  *     status = write (fd, descriptors, sizeof descriptors)
1747  *
1748  * That write establishes the device configuration, so the kernel can
1749  * bind to the controller ... guaranteeing it can handle enumeration
1750  * at all necessary speeds.  Descriptor order is:
1751  *
1752  * . message tag (u32, host order) ... for now, must be zero; it
1753  *      would change to support features like multi-config devices
1754  * . full/low speed config ... all wTotalLength bytes (with interface,
1755  *      class, altsetting, endpoint, and other descriptors)
1756  * . high speed config ... all descriptors, for high speed operation;
1757  *      this one's optional except for high-speed hardware
1758  * . device descriptor
1759  *
1760  * Endpoints are not yet enabled. Drivers must wait until device
1761  * configuration and interface altsetting changes create
1762  * the need to configure (or unconfigure) them.
1763  *
1764  * After initialization, the device stays active for as long as that
1765  * $CHIP file is open.  Events must then be read from that descriptor,
1766  * such as configuration notifications.
1767  */
1768 
1769 static int is_valid_config(struct usb_config_descriptor *config,
1770                 unsigned int total)
1771 {
1772         return config->bDescriptorType == USB_DT_CONFIG
1773                 && config->bLength == USB_DT_CONFIG_SIZE
1774                 && total >= USB_DT_CONFIG_SIZE
1775                 && config->bConfigurationValue != 0
1776                 && (config->bmAttributes & USB_CONFIG_ATT_ONE) != 0
1777                 && (config->bmAttributes & USB_CONFIG_ATT_WAKEUP) == 0;
1778         /* FIXME if gadget->is_otg, _must_ include an otg descriptor */
1779         /* FIXME check lengths: walk to end */
1780 }
1781 
1782 static ssize_t
1783 dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
1784 {
1785         struct dev_data         *dev = fd->private_data;
1786         ssize_t                 value, length = len;
1787         unsigned                total;
1788         u32                     tag;
1789         char                    *kbuf;
1790 
1791         spin_lock_irq(&dev->lock);
1792         if (dev->state > STATE_DEV_OPENED) {
1793                 value = ep0_write(fd, buf, len, ptr);
1794                 spin_unlock_irq(&dev->lock);
1795                 return value;
1796         }
1797         spin_unlock_irq(&dev->lock);
1798 
1799         if ((len < (USB_DT_CONFIG_SIZE + USB_DT_DEVICE_SIZE + 4)) ||
1800             (len > PAGE_SIZE * 4))
1801                 return -EINVAL;
1802 
1803         /* we might need to change message format someday */
1804         if (copy_from_user (&tag, buf, 4))
1805                 return -EFAULT;
1806         if (tag != 0)
1807                 return -EINVAL;
1808         buf += 4;
1809         length -= 4;
1810 
1811         kbuf = memdup_user(buf, length);
1812         if (IS_ERR(kbuf))
1813                 return PTR_ERR(kbuf);
1814 
1815         spin_lock_irq (&dev->lock);
1816         value = -EINVAL;
1817         if (dev->buf) {
1818                 kfree(kbuf);
1819                 goto fail;
1820         }
1821         dev->buf = kbuf;
1822 
1823         /* full or low speed config */
1824         dev->config = (void *) kbuf;
1825         total = le16_to_cpu(dev->config->wTotalLength);
1826         if (!is_valid_config(dev->config, total) ||
1827                         total > length - USB_DT_DEVICE_SIZE)
1828                 goto fail;
1829         kbuf += total;
1830         length -= total;
1831 
1832         /* optional high speed config */
1833         if (kbuf [1] == USB_DT_CONFIG) {
1834                 dev->hs_config = (void *) kbuf;
1835                 total = le16_to_cpu(dev->hs_config->wTotalLength);
1836                 if (!is_valid_config(dev->hs_config, total) ||
1837                                 total > length - USB_DT_DEVICE_SIZE)
1838                         goto fail;
1839                 kbuf += total;
1840                 length -= total;
1841         } else {
1842                 dev->hs_config = NULL;
1843         }
1844 
1845         /* could support multiple configs, using another encoding! */
1846 
1847         /* device descriptor (tweaked for paranoia) */
1848         if (length != USB_DT_DEVICE_SIZE)
1849                 goto fail;
1850         dev->dev = (void *)kbuf;
1851         if (dev->dev->bLength != USB_DT_DEVICE_SIZE
1852                         || dev->dev->bDescriptorType != USB_DT_DEVICE
1853                         || dev->dev->bNumConfigurations != 1)
1854                 goto fail;
1855         dev->dev->bcdUSB = cpu_to_le16 (0x0200);
1856 
1857         /* triggers gadgetfs_bind(); then we can enumerate. */
1858         spin_unlock_irq (&dev->lock);
1859         if (dev->hs_config)
1860                 gadgetfs_driver.max_speed = USB_SPEED_HIGH;
1861         else
1862                 gadgetfs_driver.max_speed = USB_SPEED_FULL;
1863 
1864         value = usb_gadget_probe_driver(&gadgetfs_driver);
1865         if (value != 0) {
1866                 kfree (dev->buf);
1867                 dev->buf = NULL;
1868         } else {
1869                 /* at this point "good" hardware has for the first time
1870                  * let the USB the host see us.  alternatively, if users
1871                  * unplug/replug that will clear all the error state.
1872                  *
1873                  * note:  everything running before here was guaranteed
1874                  * to choke driver model style diagnostics.  from here
1875                  * on, they can work ... except in cleanup paths that
1876                  * kick in after the ep0 descriptor is closed.
1877                  */
1878                 value = len;
1879                 dev->gadget_registered = true;
1880         }
1881         return value;
1882 
1883 fail:
1884         spin_unlock_irq (&dev->lock);
1885         pr_debug ("%s: %s fail %zd, %p\n", shortname, __func__, value, dev);
1886         kfree (dev->buf);
1887         dev->buf = NULL;
1888         return value;
1889 }
1890 
1891 static int
1892 dev_open (struct inode *inode, struct file *fd)
1893 {
1894         struct dev_data         *dev = inode->i_private;
1895         int                     value = -EBUSY;
1896 
1897         spin_lock_irq(&dev->lock);
1898         if (dev->state == STATE_DEV_DISABLED) {
1899                 dev->ev_next = 0;
1900                 dev->state = STATE_DEV_OPENED;
1901                 fd->private_data = dev;
1902                 get_dev (dev);
1903                 value = 0;
1904         }
1905         spin_unlock_irq(&dev->lock);
1906         return value;
1907 }
1908 
1909 static const struct file_operations ep0_operations = {
1910         .llseek =       no_llseek,
1911 
1912         .open =         dev_open,
1913         .read =         ep0_read,
1914         .write =        dev_config,
1915         .fasync =       ep0_fasync,
1916         .poll =         ep0_poll,
1917         .unlocked_ioctl = dev_ioctl,
1918         .release =      dev_release,
1919 };
1920 
1921 /*----------------------------------------------------------------------*/
1922 
1923 /* FILESYSTEM AND SUPERBLOCK OPERATIONS
1924  *
1925  * Mounting the filesystem creates a controller file, used first for
1926  * device configuration then later for event monitoring.
1927  */
1928 
1929 
1930 /* FIXME PAM etc could set this security policy without mount options
1931  * if epfiles inherited ownership and permissons from ep0 ...
1932  */
1933 
1934 static unsigned default_uid;
1935 static unsigned default_gid;
1936 static unsigned default_perm = S_IRUSR | S_IWUSR;
1937 
1938 module_param (default_uid, uint, 0644);
1939 module_param (default_gid, uint, 0644);
1940 module_param (default_perm, uint, 0644);
1941 
1942 
1943 static struct inode *
1944 gadgetfs_make_inode (struct super_block *sb,
1945                 void *data, const struct file_operations *fops,
1946                 int mode)
1947 {
1948         struct inode *inode = new_inode (sb);
1949 
1950         if (inode) {
1951                 inode->i_ino = get_next_ino();
1952                 inode->i_mode = mode;
1953                 inode->i_uid = make_kuid(&init_user_ns, default_uid);
1954                 inode->i_gid = make_kgid(&init_user_ns, default_gid);
1955                 inode->i_atime = inode->i_mtime = inode->i_ctime
1956                                 = current_time(inode);
1957                 inode->i_private = data;
1958                 inode->i_fop = fops;
1959         }
1960         return inode;
1961 }
1962 
1963 /* creates in fs root directory, so non-renamable and non-linkable.
1964  * so inode and dentry are paired, until device reconfig.
1965  */
1966 static struct dentry *
1967 gadgetfs_create_file (struct super_block *sb, char const *name,
1968                 void *data, const struct file_operations *fops)
1969 {
1970         struct dentry   *dentry;
1971         struct inode    *inode;
1972 
1973         dentry = d_alloc_name(sb->s_root, name);
1974         if (!dentry)
1975                 return NULL;
1976 
1977         inode = gadgetfs_make_inode (sb, data, fops,
1978                         S_IFREG | (default_perm & S_IRWXUGO));
1979         if (!inode) {
1980                 dput(dentry);
1981                 return NULL;
1982         }
1983         d_add (dentry, inode);
1984         return dentry;
1985 }
1986 
1987 static const struct super_operations gadget_fs_operations = {
1988         .statfs =       simple_statfs,
1989         .drop_inode =   generic_delete_inode,
1990 };
1991 
1992 static int
1993 gadgetfs_fill_super (struct super_block *sb, struct fs_context *fc)
1994 {
1995         struct inode    *inode;
1996         struct dev_data *dev;
1997 
1998         if (the_device)
1999                 return -ESRCH;
2000 
2001         CHIP = usb_get_gadget_udc_name();
2002         if (!CHIP)
2003                 return -ENODEV;
2004 
2005         /* superblock */
2006         sb->s_blocksize = PAGE_SIZE;
2007         sb->s_blocksize_bits = PAGE_SHIFT;
2008         sb->s_magic = GADGETFS_MAGIC;
2009         sb->s_op = &gadget_fs_operations;
2010         sb->s_time_gran = 1;
2011 
2012         /* root inode */
2013         inode = gadgetfs_make_inode (sb,
2014                         NULL, &simple_dir_operations,
2015                         S_IFDIR | S_IRUGO | S_IXUGO);
2016         if (!inode)
2017                 goto Enomem;
2018         inode->i_op = &simple_dir_inode_operations;
2019         if (!(sb->s_root = d_make_root (inode)))
2020                 goto Enomem;
2021 
2022         /* the ep0 file is named after the controller we expect;
2023          * user mode code can use it for sanity checks, like we do.
2024          */
2025         dev = dev_new ();
2026         if (!dev)
2027                 goto Enomem;
2028 
2029         dev->sb = sb;
2030         dev->dentry = gadgetfs_create_file(sb, CHIP, dev, &ep0_operations);
2031         if (!dev->dentry) {
2032                 put_dev(dev);
2033                 goto Enomem;
2034         }
2035 
2036         /* other endpoint files are available after hardware setup,
2037          * from binding to a controller.
2038          */
2039         the_device = dev;
2040         return 0;
2041 
2042 Enomem:
2043         return -ENOMEM;
2044 }
2045 
2046 /* "mount -t gadgetfs path /dev/gadget" ends up here */
2047 static int gadgetfs_get_tree(struct fs_context *fc)
2048 {
2049         return get_tree_single(fc, gadgetfs_fill_super);
2050 }
2051 
2052 static const struct fs_context_operations gadgetfs_context_ops = {
2053         .get_tree       = gadgetfs_get_tree,
2054 };
2055 
2056 static int gadgetfs_init_fs_context(struct fs_context *fc)
2057 {
2058         fc->ops = &gadgetfs_context_ops;
2059         return 0;
2060 }
2061 
2062 static void
2063 gadgetfs_kill_sb (struct super_block *sb)
2064 {
2065         kill_litter_super (sb);
2066         if (the_device) {
2067                 put_dev (the_device);
2068                 the_device = NULL;
2069         }
2070         kfree(CHIP);
2071         CHIP = NULL;
2072 }
2073 
2074 /*----------------------------------------------------------------------*/
2075 
2076 static struct file_system_type gadgetfs_type = {
2077         .owner          = THIS_MODULE,
2078         .name           = shortname,
2079         .init_fs_context = gadgetfs_init_fs_context,
2080         .kill_sb        = gadgetfs_kill_sb,
2081 };
2082 MODULE_ALIAS_FS("gadgetfs");
2083 
2084 /*----------------------------------------------------------------------*/
2085 
2086 static int __init init (void)
2087 {
2088         int status;
2089 
2090         status = register_filesystem (&gadgetfs_type);
2091         if (status == 0)
2092                 pr_info ("%s: %s, version " DRIVER_VERSION "\n",
2093                         shortname, driver_desc);
2094         return status;
2095 }
2096 module_init (init);
2097 
2098 static void __exit cleanup (void)
2099 {
2100         pr_debug ("unregister %s\n", shortname);
2101         unregister_filesystem (&gadgetfs_type);
2102 }
2103 module_exit (cleanup);
2104
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root/drivers/usb/gadget/legacy/inode.c

DEFINITIONS
