1 #include <linux/module.h> 2 #include <linux/string.h> 3 #include <linux/bitops.h> 4 #include <linux/slab.h> 5 #include <linux/init.h> 6 #include <linux/usb.h> 7 #include "hcd.h" 8 9 #define to_urb(d) container_of(d, struct urb, kref) 10 11 static void urb_destroy(struct kref *kref) 12 { 13 struct urb *urb = to_urb(kref); 14 kfree(urb); 15 } 16 17 /** 18 * usb_init_urb - initializes a urb so that it can be used by a USB driver 19 * @urb: pointer to the urb to initialize 20 * 21 * Initializes a urb so that the USB subsystem can use it properly. 22 * 23 * If a urb is created with a call to usb_alloc_urb() it is not 24 * necessary to call this function. Only use this if you allocate the 25 * space for a struct urb on your own. If you call this function, be 26 * careful when freeing the memory for your urb that it is no longer in 27 * use by the USB core. 28 * 29 * Only use this function if you _really_ understand what you are doing. 30 */ 31 void usb_init_urb(struct urb *urb) 32 { 33 if (urb) { 34 memset(urb, 0, sizeof(*urb)); 35 kref_init(&urb->kref); 36 spin_lock_init(&urb->lock); 37 } 38 } 39 40 /** 41 * usb_alloc_urb - creates a new urb for a USB driver to use 42 * @iso_packets: number of iso packets for this urb 43 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of 44 * valid options for this. 45 * 46 * Creates an urb for the USB driver to use, initializes a few internal 47 * structures, incrementes the usage counter, and returns a pointer to it. 48 * 49 * If no memory is available, NULL is returned. 50 * 51 * If the driver want to use this urb for interrupt, control, or bulk 52 * endpoints, pass '0' as the number of iso packets. 53 * 54 * The driver must call usb_free_urb() when it is finished with the urb. 55 */ 56 struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags) 57 { 58 struct urb *urb; 59 60 urb = kmalloc(sizeof(struct urb) + 61 iso_packets * sizeof(struct usb_iso_packet_descriptor), 62 mem_flags); 63 if (!urb) { 64 err("alloc_urb: kmalloc failed"); 65 return NULL; 66 } 67 usb_init_urb(urb); 68 return urb; 69 } 70 71 /** 72 * usb_free_urb - frees the memory used by a urb when all users of it are finished 73 * @urb: pointer to the urb to free, may be NULL 74 * 75 * Must be called when a user of a urb is finished with it. When the last user 76 * of the urb calls this function, the memory of the urb is freed. 77 * 78 * Note: The transfer buffer associated with the urb is not freed, that must be 79 * done elsewhere. 80 */ 81 void usb_free_urb(struct urb *urb) 82 { 83 if (urb) 84 kref_put(&urb->kref, urb_destroy); 85 } 86 87 /** 88 * usb_get_urb - increments the reference count of the urb 89 * @urb: pointer to the urb to modify, may be NULL 90 * 91 * This must be called whenever a urb is transferred from a device driver to a 92 * host controller driver. This allows proper reference counting to happen 93 * for urbs. 94 * 95 * A pointer to the urb with the incremented reference counter is returned. 96 */ 97 struct urb * usb_get_urb(struct urb *urb) 98 { 99 if (urb) 100 kref_get(&urb->kref); 101 return urb; 102 } 103 104 105 /*-------------------------------------------------------------------*/ 106 107 /** 108 * usb_submit_urb - issue an asynchronous transfer request for an endpoint 109 * @urb: pointer to the urb describing the request 110 * @mem_flags: the type of memory to allocate, see kmalloc() for a list 111 * of valid options for this. 112 * 113 * This submits a transfer request, and transfers control of the URB 114 * describing that request to the USB subsystem. Request completion will 115 * be indicated later, asynchronously, by calling the completion handler. 116 * The three types of completion are success, error, and unlink 117 * (a software-induced fault, also called "request cancellation"). 118 * 119 * URBs may be submitted in interrupt context. 120 * 121 * The caller must have correctly initialized the URB before submitting 122 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are 123 * available to ensure that most fields are correctly initialized, for 124 * the particular kind of transfer, although they will not initialize 125 * any transfer flags. 126 * 127 * Successful submissions return 0; otherwise this routine returns a 128 * negative error number. If the submission is successful, the complete() 129 * callback from the URB will be called exactly once, when the USB core and 130 * Host Controller Driver (HCD) are finished with the URB. When the completion 131 * function is called, control of the URB is returned to the device 132 * driver which issued the request. The completion handler may then 133 * immediately free or reuse that URB. 134 * 135 * With few exceptions, USB device drivers should never access URB fields 136 * provided by usbcore or the HCD until its complete() is called. 137 * The exceptions relate to periodic transfer scheduling. For both 138 * interrupt and isochronous urbs, as part of successful URB submission 139 * urb->interval is modified to reflect the actual transfer period used 140 * (normally some power of two units). And for isochronous urbs, 141 * urb->start_frame is modified to reflect when the URB's transfers were 142 * scheduled to start. Not all isochronous transfer scheduling policies 143 * will work, but most host controller drivers should easily handle ISO 144 * queues going from now until 10-200 msec into the future. 145 * 146 * For control endpoints, the synchronous usb_control_msg() call is 147 * often used (in non-interrupt context) instead of this call. 148 * That is often used through convenience wrappers, for the requests 149 * that are standardized in the USB 2.0 specification. For bulk 150 * endpoints, a synchronous usb_bulk_msg() call is available. 151 * 152 * Request Queuing: 153 * 154 * URBs may be submitted to endpoints before previous ones complete, to 155 * minimize the impact of interrupt latencies and system overhead on data 156 * throughput. With that queuing policy, an endpoint's queue would never 157 * be empty. This is required for continuous isochronous data streams, 158 * and may also be required for some kinds of interrupt transfers. Such 159 * queuing also maximizes bandwidth utilization by letting USB controllers 160 * start work on later requests before driver software has finished the 161 * completion processing for earlier (successful) requests. 162 * 163 * As of Linux 2.6, all USB endpoint transfer queues support depths greater 164 * than one. This was previously a HCD-specific behavior, except for ISO 165 * transfers. Non-isochronous endpoint queues are inactive during cleanup 166 * after faults (transfer errors or cancellation). 167 * 168 * Reserved Bandwidth Transfers: 169 * 170 * Periodic transfers (interrupt or isochronous) are performed repeatedly, 171 * using the interval specified in the urb. Submitting the first urb to 172 * the endpoint reserves the bandwidth necessary to make those transfers. 173 * If the USB subsystem can't allocate sufficient bandwidth to perform 174 * the periodic request, submitting such a periodic request should fail. 175 * 176 * Device drivers must explicitly request that repetition, by ensuring that 177 * some URB is always on the endpoint's queue (except possibly for short 178 * periods during completion callacks). When there is no longer an urb 179 * queued, the endpoint's bandwidth reservation is canceled. This means 180 * drivers can use their completion handlers to ensure they keep bandwidth 181 * they need, by reinitializing and resubmitting the just-completed urb 182 * until the driver longer needs that periodic bandwidth. 183 * 184 * Memory Flags: 185 * 186 * The general rules for how to decide which mem_flags to use 187 * are the same as for kmalloc. There are four 188 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and 189 * GFP_ATOMIC. 190 * 191 * GFP_NOFS is not ever used, as it has not been implemented yet. 192 * 193 * GFP_ATOMIC is used when 194 * (a) you are inside a completion handler, an interrupt, bottom half, 195 * tasklet or timer, or 196 * (b) you are holding a spinlock or rwlock (does not apply to 197 * semaphores), or 198 * (c) current->state != TASK_RUNNING, this is the case only after 199 * you've changed it. 200 * 201 * GFP_NOIO is used in the block io path and error handling of storage 202 * devices. 203 * 204 * All other situations use GFP_KERNEL. 205 * 206 * Some more specific rules for mem_flags can be inferred, such as 207 * (1) start_xmit, timeout, and receive methods of network drivers must 208 * use GFP_ATOMIC (they are called with a spinlock held); 209 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also 210 * called with a spinlock held); 211 * (3) If you use a kernel thread with a network driver you must use 212 * GFP_NOIO, unless (b) or (c) apply; 213 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c) 214 * apply or your are in a storage driver's block io path; 215 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and 216 * (6) changing firmware on a running storage or net device uses 217 * GFP_NOIO, unless b) or c) apply 218 * 219 */ 220 int usb_submit_urb(struct urb *urb, gfp_t mem_flags) 221 { 222 int pipe, temp, max; 223 struct usb_device *dev; 224 int is_out; 225 226 if (!urb || urb->hcpriv || !urb->complete) 227 return -EINVAL; 228 if (!(dev = urb->dev) || 229 (dev->state < USB_STATE_DEFAULT) || 230 (!dev->bus) || (dev->devnum <= 0)) 231 return -ENODEV; 232 if (dev->bus->controller->power.power_state.event != PM_EVENT_ON 233 || dev->state == USB_STATE_SUSPENDED) 234 return -EHOSTUNREACH; 235 236 urb->status = -EINPROGRESS; 237 urb->actual_length = 0; 238 239 /* Lots of sanity checks, so HCDs can rely on clean data 240 * and don't need to duplicate tests 241 */ 242 pipe = urb->pipe; 243 temp = usb_pipetype(pipe); 244 is_out = usb_pipeout(pipe); 245 246 if (!usb_pipecontrol(pipe) && dev->state < USB_STATE_CONFIGURED) 247 return -ENODEV; 248 249 /* FIXME there should be a sharable lock protecting us against 250 * config/altsetting changes and disconnects, kicking in here. 251 * (here == before maxpacket, and eventually endpoint type, 252 * checks get made.) 253 */ 254 255 max = usb_maxpacket(dev, pipe, is_out); 256 if (max <= 0) { 257 dev_dbg(&dev->dev, 258 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n", 259 usb_pipeendpoint(pipe), is_out ? "out" : "in", 260 __FUNCTION__, max); 261 return -EMSGSIZE; 262 } 263 264 /* periodic transfers limit size per frame/uframe, 265 * but drivers only control those sizes for ISO. 266 * while we're checking, initialize return status. 267 */ 268 if (temp == PIPE_ISOCHRONOUS) { 269 int n, len; 270 271 /* "high bandwidth" mode, 1-3 packets/uframe? */ 272 if (dev->speed == USB_SPEED_HIGH) { 273 int mult = 1 + ((max >> 11) & 0x03); 274 max &= 0x07ff; 275 max *= mult; 276 } 277 278 if (urb->number_of_packets <= 0) 279 return -EINVAL; 280 for (n = 0; n < urb->number_of_packets; n++) { 281 len = urb->iso_frame_desc[n].length; 282 if (len < 0 || len > max) 283 return -EMSGSIZE; 284 urb->iso_frame_desc[n].status = -EXDEV; 285 urb->iso_frame_desc[n].actual_length = 0; 286 } 287 } 288 289 /* the I/O buffer must be mapped/unmapped, except when length=0 */ 290 if (urb->transfer_buffer_length < 0) 291 return -EMSGSIZE; 292 293 #ifdef DEBUG 294 /* stuff that drivers shouldn't do, but which shouldn't 295 * cause problems in HCDs if they get it wrong. 296 */ 297 { 298 unsigned int orig_flags = urb->transfer_flags; 299 unsigned int allowed; 300 301 /* enforce simple/standard policy */ 302 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP | 303 URB_NO_INTERRUPT); 304 switch (temp) { 305 case PIPE_BULK: 306 if (is_out) 307 allowed |= URB_ZERO_PACKET; 308 /* FALLTHROUGH */ 309 case PIPE_CONTROL: 310 allowed |= URB_NO_FSBR; /* only affects UHCI */ 311 /* FALLTHROUGH */ 312 default: /* all non-iso endpoints */ 313 if (!is_out) 314 allowed |= URB_SHORT_NOT_OK; 315 break; 316 case PIPE_ISOCHRONOUS: 317 allowed |= URB_ISO_ASAP; 318 break; 319 } 320 urb->transfer_flags &= allowed; 321 322 /* fail if submitter gave bogus flags */ 323 if (urb->transfer_flags != orig_flags) { 324 err("BOGUS urb flags, %x --> %x", 325 orig_flags, urb->transfer_flags); 326 return -EINVAL; 327 } 328 } 329 #endif 330 /* 331 * Force periodic transfer intervals to be legal values that are 332 * a power of two (so HCDs don't need to). 333 * 334 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC 335 * supports different values... this uses EHCI/UHCI defaults (and 336 * EHCI can use smaller non-default values). 337 */ 338 switch (temp) { 339 case PIPE_ISOCHRONOUS: 340 case PIPE_INTERRUPT: 341 /* too small? */ 342 if (urb->interval <= 0) 343 return -EINVAL; 344 /* too big? */ 345 switch (dev->speed) { 346 case USB_SPEED_HIGH: /* units are microframes */ 347 // NOTE usb handles 2^15 348 if (urb->interval > (1024 * 8)) 349 urb->interval = 1024 * 8; 350 temp = 1024 * 8; 351 break; 352 case USB_SPEED_FULL: /* units are frames/msec */ 353 case USB_SPEED_LOW: 354 if (temp == PIPE_INTERRUPT) { 355 if (urb->interval > 255) 356 return -EINVAL; 357 // NOTE ohci only handles up to 32 358 temp = 128; 359 } else { 360 if (urb->interval > 1024) 361 urb->interval = 1024; 362 // NOTE usb and ohci handle up to 2^15 363 temp = 1024; 364 } 365 break; 366 default: 367 return -EINVAL; 368 } 369 /* power of two? */ 370 while (temp > urb->interval) 371 temp >>= 1; 372 urb->interval = temp; 373 } 374 375 return usb_hcd_submit_urb(urb, mem_flags); 376 } 377 378 /*-------------------------------------------------------------------*/ 379 380 /** 381 * usb_unlink_urb - abort/cancel a transfer request for an endpoint 382 * @urb: pointer to urb describing a previously submitted request, 383 * may be NULL 384 * 385 * This routine cancels an in-progress request. URBs complete only 386 * once per submission, and may be canceled only once per submission. 387 * Successful cancellation means the requests's completion handler will 388 * be called with a status code indicating that the request has been 389 * canceled (rather than any other code) and will quickly be removed 390 * from host controller data structures. 391 * 392 * This request is always asynchronous. 393 * Success is indicated by returning -EINPROGRESS, 394 * at which time the URB will normally have been unlinked but not yet 395 * given back to the device driver. When it is called, the completion 396 * function will see urb->status == -ECONNRESET. Failure is indicated 397 * by any other return value. Unlinking will fail when the URB is not 398 * currently "linked" (i.e., it was never submitted, or it was unlinked 399 * before, or the hardware is already finished with it), even if the 400 * completion handler has not yet run. 401 * 402 * Unlinking and Endpoint Queues: 403 * 404 * Host Controller Drivers (HCDs) place all the URBs for a particular 405 * endpoint in a queue. Normally the queue advances as the controller 406 * hardware processes each request. But when an URB terminates with an 407 * error its queue stops, at least until that URB's completion routine 408 * returns. It is guaranteed that the queue will not restart until all 409 * its unlinked URBs have been fully retired, with their completion 410 * routines run, even if that's not until some time after the original 411 * completion handler returns. Normally the same behavior and guarantees 412 * apply when an URB terminates because it was unlinked; however if an 413 * URB is unlinked before the hardware has started to execute it, then 414 * its queue is not guaranteed to stop until all the preceding URBs have 415 * completed. 416 * 417 * This means that USB device drivers can safely build deep queues for 418 * large or complex transfers, and clean them up reliably after any sort 419 * of aborted transfer by unlinking all pending URBs at the first fault. 420 * 421 * Note that an URB terminating early because a short packet was received 422 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set. 423 * Also, that all unlinks performed in any URB completion handler must 424 * be asynchronous. 425 * 426 * Queues for isochronous endpoints are treated differently, because they 427 * advance at fixed rates. Such queues do not stop when an URB is unlinked. 428 * An unlinked URB may leave a gap in the stream of packets. It is undefined 429 * whether such gaps can be filled in. 430 * 431 * When a control URB terminates with an error, it is likely that the 432 * status stage of the transfer will not take place, even if it is merely 433 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set. 434 */ 435 int usb_unlink_urb(struct urb *urb) 436 { 437 if (!urb) 438 return -EINVAL; 439 if (!(urb->dev && urb->dev->bus)) 440 return -ENODEV; 441 return usb_hcd_unlink_urb(urb, -ECONNRESET); 442 } 443 444 /** 445 * usb_kill_urb - cancel a transfer request and wait for it to finish 446 * @urb: pointer to URB describing a previously submitted request, 447 * may be NULL 448 * 449 * This routine cancels an in-progress request. It is guaranteed that 450 * upon return all completion handlers will have finished and the URB 451 * will be totally idle and available for reuse. These features make 452 * this an ideal way to stop I/O in a disconnect() callback or close() 453 * function. If the request has not already finished or been unlinked 454 * the completion handler will see urb->status == -ENOENT. 455 * 456 * While the routine is running, attempts to resubmit the URB will fail 457 * with error -EPERM. Thus even if the URB's completion handler always 458 * tries to resubmit, it will not succeed and the URB will become idle. 459 * 460 * This routine may not be used in an interrupt context (such as a bottom 461 * half or a completion handler), or when holding a spinlock, or in other 462 * situations where the caller can't schedule(). 463 */ 464 void usb_kill_urb(struct urb *urb) 465 { 466 might_sleep(); 467 if (!(urb && urb->dev && urb->dev->bus)) 468 return; 469 spin_lock_irq(&urb->lock); 470 ++urb->reject; 471 spin_unlock_irq(&urb->lock); 472 473 usb_hcd_unlink_urb(urb, -ENOENT); 474 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); 475 476 spin_lock_irq(&urb->lock); 477 --urb->reject; 478 spin_unlock_irq(&urb->lock); 479 } 480 481 EXPORT_SYMBOL(usb_init_urb); 482 EXPORT_SYMBOL(usb_alloc_urb); 483 EXPORT_SYMBOL(usb_free_urb); 484 EXPORT_SYMBOL(usb_get_urb); 485 EXPORT_SYMBOL(usb_submit_urb); 486 EXPORT_SYMBOL(usb_unlink_urb); 487 EXPORT_SYMBOL(usb_kill_urb); 488 489