1 #include <linux/config.h> 2 #include <linux/module.h> 3 #include <linux/string.h> 4 #include <linux/bitops.h> 5 #include <linux/slab.h> 6 #include <linux/init.h> 7 8 #ifdef CONFIG_USB_DEBUG 9 #define DEBUG 10 #else 11 #undef DEBUG 12 #endif 13 #include <linux/usb.h> 14 #include "hcd.h" 15 16 #define to_urb(d) container_of(d, struct urb, kref) 17 18 static void urb_destroy(struct kref *kref) 19 { 20 struct urb *urb = to_urb(kref); 21 kfree(urb); 22 } 23 24 /** 25 * usb_init_urb - initializes a urb so that it can be used by a USB driver 26 * @urb: pointer to the urb to initialize 27 * 28 * Initializes a urb so that the USB subsystem can use it properly. 29 * 30 * If a urb is created with a call to usb_alloc_urb() it is not 31 * necessary to call this function. Only use this if you allocate the 32 * space for a struct urb on your own. If you call this function, be 33 * careful when freeing the memory for your urb that it is no longer in 34 * use by the USB core. 35 * 36 * Only use this function if you _really_ understand what you are doing. 37 */ 38 void usb_init_urb(struct urb *urb) 39 { 40 if (urb) { 41 memset(urb, 0, sizeof(*urb)); 42 kref_init(&urb->kref); 43 spin_lock_init(&urb->lock); 44 } 45 } 46 47 /** 48 * usb_alloc_urb - creates a new urb for a USB driver to use 49 * @iso_packets: number of iso packets for this urb 50 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of 51 * valid options for this. 52 * 53 * Creates an urb for the USB driver to use, initializes a few internal 54 * structures, incrementes the usage counter, and returns a pointer to it. 55 * 56 * If no memory is available, NULL is returned. 57 * 58 * If the driver want to use this urb for interrupt, control, or bulk 59 * endpoints, pass '0' as the number of iso packets. 60 * 61 * The driver must call usb_free_urb() when it is finished with the urb. 62 */ 63 struct urb *usb_alloc_urb(int iso_packets, unsigned mem_flags) 64 { 65 struct urb *urb; 66 67 urb = (struct urb *)kmalloc(sizeof(struct urb) + 68 iso_packets * sizeof(struct usb_iso_packet_descriptor), 69 mem_flags); 70 if (!urb) { 71 err("alloc_urb: kmalloc failed"); 72 return NULL; 73 } 74 usb_init_urb(urb); 75 return urb; 76 } 77 78 /** 79 * usb_free_urb - frees the memory used by a urb when all users of it are finished 80 * @urb: pointer to the urb to free, may be NULL 81 * 82 * Must be called when a user of a urb is finished with it. When the last user 83 * of the urb calls this function, the memory of the urb is freed. 84 * 85 * Note: The transfer buffer associated with the urb is not freed, that must be 86 * done elsewhere. 87 */ 88 void usb_free_urb(struct urb *urb) 89 { 90 if (urb) 91 kref_put(&urb->kref, urb_destroy); 92 } 93 94 /** 95 * usb_get_urb - increments the reference count of the urb 96 * @urb: pointer to the urb to modify, may be NULL 97 * 98 * This must be called whenever a urb is transferred from a device driver to a 99 * host controller driver. This allows proper reference counting to happen 100 * for urbs. 101 * 102 * A pointer to the urb with the incremented reference counter is returned. 103 */ 104 struct urb * usb_get_urb(struct urb *urb) 105 { 106 if (urb) 107 kref_get(&urb->kref); 108 return urb; 109 } 110 111 112 /*-------------------------------------------------------------------*/ 113 114 /** 115 * usb_submit_urb - issue an asynchronous transfer request for an endpoint 116 * @urb: pointer to the urb describing the request 117 * @mem_flags: the type of memory to allocate, see kmalloc() for a list 118 * of valid options for this. 119 * 120 * This submits a transfer request, and transfers control of the URB 121 * describing that request to the USB subsystem. Request completion will 122 * be indicated later, asynchronously, by calling the completion handler. 123 * The three types of completion are success, error, and unlink 124 * (a software-induced fault, also called "request cancellation"). 125 * 126 * URBs may be submitted in interrupt context. 127 * 128 * The caller must have correctly initialized the URB before submitting 129 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are 130 * available to ensure that most fields are correctly initialized, for 131 * the particular kind of transfer, although they will not initialize 132 * any transfer flags. 133 * 134 * Successful submissions return 0; otherwise this routine returns a 135 * negative error number. If the submission is successful, the complete() 136 * callback from the URB will be called exactly once, when the USB core and 137 * Host Controller Driver (HCD) are finished with the URB. When the completion 138 * function is called, control of the URB is returned to the device 139 * driver which issued the request. The completion handler may then 140 * immediately free or reuse that URB. 141 * 142 * With few exceptions, USB device drivers should never access URB fields 143 * provided by usbcore or the HCD until its complete() is called. 144 * The exceptions relate to periodic transfer scheduling. For both 145 * interrupt and isochronous urbs, as part of successful URB submission 146 * urb->interval is modified to reflect the actual transfer period used 147 * (normally some power of two units). And for isochronous urbs, 148 * urb->start_frame is modified to reflect when the URB's transfers were 149 * scheduled to start. Not all isochronous transfer scheduling policies 150 * will work, but most host controller drivers should easily handle ISO 151 * queues going from now until 10-200 msec into the future. 152 * 153 * For control endpoints, the synchronous usb_control_msg() call is 154 * often used (in non-interrupt context) instead of this call. 155 * That is often used through convenience wrappers, for the requests 156 * that are standardized in the USB 2.0 specification. For bulk 157 * endpoints, a synchronous usb_bulk_msg() call is available. 158 * 159 * Request Queuing: 160 * 161 * URBs may be submitted to endpoints before previous ones complete, to 162 * minimize the impact of interrupt latencies and system overhead on data 163 * throughput. With that queuing policy, an endpoint's queue would never 164 * be empty. This is required for continuous isochronous data streams, 165 * and may also be required for some kinds of interrupt transfers. Such 166 * queuing also maximizes bandwidth utilization by letting USB controllers 167 * start work on later requests before driver software has finished the 168 * completion processing for earlier (successful) requests. 169 * 170 * As of Linux 2.6, all USB endpoint transfer queues support depths greater 171 * than one. This was previously a HCD-specific behavior, except for ISO 172 * transfers. Non-isochronous endpoint queues are inactive during cleanup 173 * after faults (transfer errors or cancellation). 174 * 175 * Reserved Bandwidth Transfers: 176 * 177 * Periodic transfers (interrupt or isochronous) are performed repeatedly, 178 * using the interval specified in the urb. Submitting the first urb to 179 * the endpoint reserves the bandwidth necessary to make those transfers. 180 * If the USB subsystem can't allocate sufficient bandwidth to perform 181 * the periodic request, submitting such a periodic request should fail. 182 * 183 * Device drivers must explicitly request that repetition, by ensuring that 184 * some URB is always on the endpoint's queue (except possibly for short 185 * periods during completion callacks). When there is no longer an urb 186 * queued, the endpoint's bandwidth reservation is canceled. This means 187 * drivers can use their completion handlers to ensure they keep bandwidth 188 * they need, by reinitializing and resubmitting the just-completed urb 189 * until the driver longer needs that periodic bandwidth. 190 * 191 * Memory Flags: 192 * 193 * The general rules for how to decide which mem_flags to use 194 * are the same as for kmalloc. There are four 195 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and 196 * GFP_ATOMIC. 197 * 198 * GFP_NOFS is not ever used, as it has not been implemented yet. 199 * 200 * GFP_ATOMIC is used when 201 * (a) you are inside a completion handler, an interrupt, bottom half, 202 * tasklet or timer, or 203 * (b) you are holding a spinlock or rwlock (does not apply to 204 * semaphores), or 205 * (c) current->state != TASK_RUNNING, this is the case only after 206 * you've changed it. 207 * 208 * GFP_NOIO is used in the block io path and error handling of storage 209 * devices. 210 * 211 * All other situations use GFP_KERNEL. 212 * 213 * Some more specific rules for mem_flags can be inferred, such as 214 * (1) start_xmit, timeout, and receive methods of network drivers must 215 * use GFP_ATOMIC (they are called with a spinlock held); 216 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also 217 * called with a spinlock held); 218 * (3) If you use a kernel thread with a network driver you must use 219 * GFP_NOIO, unless (b) or (c) apply; 220 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c) 221 * apply or your are in a storage driver's block io path; 222 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and 223 * (6) changing firmware on a running storage or net device uses 224 * GFP_NOIO, unless b) or c) apply 225 * 226 */ 227 int usb_submit_urb(struct urb *urb, unsigned mem_flags) 228 { 229 int pipe, temp, max; 230 struct usb_device *dev; 231 struct usb_operations *op; 232 int is_out; 233 234 if (!urb || urb->hcpriv || !urb->complete) 235 return -EINVAL; 236 if (!(dev = urb->dev) || 237 (dev->state < USB_STATE_DEFAULT) || 238 (!dev->bus) || (dev->devnum <= 0)) 239 return -ENODEV; 240 if (dev->state == USB_STATE_SUSPENDED) 241 return -EHOSTUNREACH; 242 if (!(op = dev->bus->op) || !op->submit_urb) 243 return -ENODEV; 244 245 urb->status = -EINPROGRESS; 246 urb->actual_length = 0; 247 urb->bandwidth = 0; 248 249 /* Lots of sanity checks, so HCDs can rely on clean data 250 * and don't need to duplicate tests 251 */ 252 pipe = urb->pipe; 253 temp = usb_pipetype (pipe); 254 is_out = usb_pipeout (pipe); 255 256 if (!usb_pipecontrol (pipe) && dev->state < USB_STATE_CONFIGURED) 257 return -ENODEV; 258 259 /* FIXME there should be a sharable lock protecting us against 260 * config/altsetting changes and disconnects, kicking in here. 261 * (here == before maxpacket, and eventually endpoint type, 262 * checks get made.) 263 */ 264 265 max = usb_maxpacket (dev, pipe, is_out); 266 if (max <= 0) { 267 dev_dbg(&dev->dev, 268 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n", 269 usb_pipeendpoint (pipe), is_out ? "out" : "in", 270 __FUNCTION__, max); 271 return -EMSGSIZE; 272 } 273 274 /* periodic transfers limit size per frame/uframe, 275 * but drivers only control those sizes for ISO. 276 * while we're checking, initialize return status. 277 */ 278 if (temp == PIPE_ISOCHRONOUS) { 279 int n, len; 280 281 /* "high bandwidth" mode, 1-3 packets/uframe? */ 282 if (dev->speed == USB_SPEED_HIGH) { 283 int mult = 1 + ((max >> 11) & 0x03); 284 max &= 0x07ff; 285 max *= mult; 286 } 287 288 if (urb->number_of_packets <= 0) 289 return -EINVAL; 290 for (n = 0; n < urb->number_of_packets; n++) { 291 len = urb->iso_frame_desc [n].length; 292 if (len < 0 || len > max) 293 return -EMSGSIZE; 294 urb->iso_frame_desc [n].status = -EXDEV; 295 urb->iso_frame_desc [n].actual_length = 0; 296 } 297 } 298 299 /* the I/O buffer must be mapped/unmapped, except when length=0 */ 300 if (urb->transfer_buffer_length < 0) 301 return -EMSGSIZE; 302 303 #ifdef DEBUG 304 /* stuff that drivers shouldn't do, but which shouldn't 305 * cause problems in HCDs if they get it wrong. 306 */ 307 { 308 unsigned int orig_flags = urb->transfer_flags; 309 unsigned int allowed; 310 311 /* enforce simple/standard policy */ 312 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP | 313 URB_NO_INTERRUPT); 314 switch (temp) { 315 case PIPE_BULK: 316 if (is_out) 317 allowed |= URB_ZERO_PACKET; 318 /* FALLTHROUGH */ 319 case PIPE_CONTROL: 320 allowed |= URB_NO_FSBR; /* only affects UHCI */ 321 /* FALLTHROUGH */ 322 default: /* all non-iso endpoints */ 323 if (!is_out) 324 allowed |= URB_SHORT_NOT_OK; 325 break; 326 case PIPE_ISOCHRONOUS: 327 allowed |= URB_ISO_ASAP; 328 break; 329 } 330 urb->transfer_flags &= allowed; 331 332 /* fail if submitter gave bogus flags */ 333 if (urb->transfer_flags != orig_flags) { 334 err ("BOGUS urb flags, %x --> %x", 335 orig_flags, urb->transfer_flags); 336 return -EINVAL; 337 } 338 } 339 #endif 340 /* 341 * Force periodic transfer intervals to be legal values that are 342 * a power of two (so HCDs don't need to). 343 * 344 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC 345 * supports different values... this uses EHCI/UHCI defaults (and 346 * EHCI can use smaller non-default values). 347 */ 348 switch (temp) { 349 case PIPE_ISOCHRONOUS: 350 case PIPE_INTERRUPT: 351 /* too small? */ 352 if (urb->interval <= 0) 353 return -EINVAL; 354 /* too big? */ 355 switch (dev->speed) { 356 case USB_SPEED_HIGH: /* units are microframes */ 357 // NOTE usb handles 2^15 358 if (urb->interval > (1024 * 8)) 359 urb->interval = 1024 * 8; 360 temp = 1024 * 8; 361 break; 362 case USB_SPEED_FULL: /* units are frames/msec */ 363 case USB_SPEED_LOW: 364 if (temp == PIPE_INTERRUPT) { 365 if (urb->interval > 255) 366 return -EINVAL; 367 // NOTE ohci only handles up to 32 368 temp = 128; 369 } else { 370 if (urb->interval > 1024) 371 urb->interval = 1024; 372 // NOTE usb and ohci handle up to 2^15 373 temp = 1024; 374 } 375 break; 376 default: 377 return -EINVAL; 378 } 379 /* power of two? */ 380 while (temp > urb->interval) 381 temp >>= 1; 382 urb->interval = temp; 383 } 384 385 return op->submit_urb (urb, mem_flags); 386 } 387 388 /*-------------------------------------------------------------------*/ 389 390 /** 391 * usb_unlink_urb - abort/cancel a transfer request for an endpoint 392 * @urb: pointer to urb describing a previously submitted request, 393 * may be NULL 394 * 395 * This routine cancels an in-progress request. URBs complete only 396 * once per submission, and may be canceled only once per submission. 397 * Successful cancellation means the requests's completion handler will 398 * be called with a status code indicating that the request has been 399 * canceled (rather than any other code) and will quickly be removed 400 * from host controller data structures. 401 * 402 * This request is always asynchronous. 403 * Success is indicated by returning -EINPROGRESS, 404 * at which time the URB will normally have been unlinked but not yet 405 * given back to the device driver. When it is called, the completion 406 * function will see urb->status == -ECONNRESET. Failure is indicated 407 * by any other return value. Unlinking will fail when the URB is not 408 * currently "linked" (i.e., it was never submitted, or it was unlinked 409 * before, or the hardware is already finished with it), even if the 410 * completion handler has not yet run. 411 * 412 * Unlinking and Endpoint Queues: 413 * 414 * Host Controller Drivers (HCDs) place all the URBs for a particular 415 * endpoint in a queue. Normally the queue advances as the controller 416 * hardware processes each request. But when an URB terminates with an 417 * error its queue stops, at least until that URB's completion routine 418 * returns. It is guaranteed that the queue will not restart until all 419 * its unlinked URBs have been fully retired, with their completion 420 * routines run, even if that's not until some time after the original 421 * completion handler returns. Normally the same behavior and guarantees 422 * apply when an URB terminates because it was unlinked; however if an 423 * URB is unlinked before the hardware has started to execute it, then 424 * its queue is not guaranteed to stop until all the preceding URBs have 425 * completed. 426 * 427 * This means that USB device drivers can safely build deep queues for 428 * large or complex transfers, and clean them up reliably after any sort 429 * of aborted transfer by unlinking all pending URBs at the first fault. 430 * 431 * Note that an URB terminating early because a short packet was received 432 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set. 433 * Also, that all unlinks performed in any URB completion handler must 434 * be asynchronous. 435 * 436 * Queues for isochronous endpoints are treated differently, because they 437 * advance at fixed rates. Such queues do not stop when an URB is unlinked. 438 * An unlinked URB may leave a gap in the stream of packets. It is undefined 439 * whether such gaps can be filled in. 440 * 441 * When a control URB terminates with an error, it is likely that the 442 * status stage of the transfer will not take place, even if it is merely 443 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set. 444 */ 445 int usb_unlink_urb(struct urb *urb) 446 { 447 if (!urb) 448 return -EINVAL; 449 if (!(urb->dev && urb->dev->bus && urb->dev->bus->op)) 450 return -ENODEV; 451 return urb->dev->bus->op->unlink_urb(urb, -ECONNRESET); 452 } 453 454 /** 455 * usb_kill_urb - cancel a transfer request and wait for it to finish 456 * @urb: pointer to URB describing a previously submitted request, 457 * may be NULL 458 * 459 * This routine cancels an in-progress request. It is guaranteed that 460 * upon return all completion handlers will have finished and the URB 461 * will be totally idle and available for reuse. These features make 462 * this an ideal way to stop I/O in a disconnect() callback or close() 463 * function. If the request has not already finished or been unlinked 464 * the completion handler will see urb->status == -ENOENT. 465 * 466 * While the routine is running, attempts to resubmit the URB will fail 467 * with error -EPERM. Thus even if the URB's completion handler always 468 * tries to resubmit, it will not succeed and the URB will become idle. 469 * 470 * This routine may not be used in an interrupt context (such as a bottom 471 * half or a completion handler), or when holding a spinlock, or in other 472 * situations where the caller can't schedule(). 473 */ 474 void usb_kill_urb(struct urb *urb) 475 { 476 if (!(urb && urb->dev && urb->dev->bus && urb->dev->bus->op)) 477 return; 478 spin_lock_irq(&urb->lock); 479 ++urb->reject; 480 spin_unlock_irq(&urb->lock); 481 482 urb->dev->bus->op->unlink_urb(urb, -ENOENT); 483 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); 484 485 spin_lock_irq(&urb->lock); 486 --urb->reject; 487 spin_unlock_irq(&urb->lock); 488 } 489 490 EXPORT_SYMBOL(usb_init_urb); 491 EXPORT_SYMBOL(usb_alloc_urb); 492 EXPORT_SYMBOL(usb_free_urb); 493 EXPORT_SYMBOL(usb_get_urb); 494 EXPORT_SYMBOL(usb_submit_urb); 495 EXPORT_SYMBOL(usb_unlink_urb); 496 EXPORT_SYMBOL(usb_kill_urb); 497 498