xref: /openbmc/linux/drivers/usb/core/usb.c (revision 643d1f7f)
1 /*
2  * drivers/usb/core/usb.c
3  *
4  * (C) Copyright Linus Torvalds 1999
5  * (C) Copyright Johannes Erdfelt 1999-2001
6  * (C) Copyright Andreas Gal 1999
7  * (C) Copyright Gregory P. Smith 1999
8  * (C) Copyright Deti Fliegl 1999 (new USB architecture)
9  * (C) Copyright Randy Dunlap 2000
10  * (C) Copyright David Brownell 2000-2004
11  * (C) Copyright Yggdrasil Computing, Inc. 2000
12  *     (usb_device_id matching changes by Adam J. Richter)
13  * (C) Copyright Greg Kroah-Hartman 2002-2003
14  *
15  * NOTE! This is not actually a driver at all, rather this is
16  * just a collection of helper routines that implement the
17  * generic USB things that the real drivers can use..
18  *
19  * Think of this as a "USB library" rather than anything else.
20  * It should be considered a slave, with no callbacks. Callbacks
21  * are evil.
22  */
23 
24 #include <linux/module.h>
25 #include <linux/moduleparam.h>
26 #include <linux/string.h>
27 #include <linux/bitops.h>
28 #include <linux/slab.h>
29 #include <linux/interrupt.h>  /* for in_interrupt() */
30 #include <linux/kmod.h>
31 #include <linux/init.h>
32 #include <linux/spinlock.h>
33 #include <linux/errno.h>
34 #include <linux/usb.h>
35 #include <linux/mutex.h>
36 #include <linux/workqueue.h>
37 
38 #include <asm/io.h>
39 #include <linux/scatterlist.h>
40 #include <linux/mm.h>
41 #include <linux/dma-mapping.h>
42 
43 #include "hcd.h"
44 #include "usb.h"
45 
46 
47 const char *usbcore_name = "usbcore";
48 
49 static int nousb;	/* Disable USB when built into kernel image */
50 
51 /* Workqueue for autosuspend and for remote wakeup of root hubs */
52 struct workqueue_struct *ksuspend_usb_wq;
53 
54 #ifdef	CONFIG_USB_SUSPEND
55 static int usb_autosuspend_delay = 2;		/* Default delay value,
56 						 * in seconds */
57 module_param_named(autosuspend, usb_autosuspend_delay, int, 0644);
58 MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
59 
60 #else
61 #define usb_autosuspend_delay		0
62 #endif
63 
64 
65 /**
66  * usb_ifnum_to_if - get the interface object with a given interface number
67  * @dev: the device whose current configuration is considered
68  * @ifnum: the desired interface
69  *
70  * This walks the device descriptor for the currently active configuration
71  * and returns a pointer to the interface with that particular interface
72  * number, or null.
73  *
74  * Note that configuration descriptors are not required to assign interface
75  * numbers sequentially, so that it would be incorrect to assume that
76  * the first interface in that descriptor corresponds to interface zero.
77  * This routine helps device drivers avoid such mistakes.
78  * However, you should make sure that you do the right thing with any
79  * alternate settings available for this interfaces.
80  *
81  * Don't call this function unless you are bound to one of the interfaces
82  * on this device or you have locked the device!
83  */
84 struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev,
85 				      unsigned ifnum)
86 {
87 	struct usb_host_config *config = dev->actconfig;
88 	int i;
89 
90 	if (!config)
91 		return NULL;
92 	for (i = 0; i < config->desc.bNumInterfaces; i++)
93 		if (config->interface[i]->altsetting[0]
94 				.desc.bInterfaceNumber == ifnum)
95 			return config->interface[i];
96 
97 	return NULL;
98 }
99 EXPORT_SYMBOL_GPL(usb_ifnum_to_if);
100 
101 /**
102  * usb_altnum_to_altsetting - get the altsetting structure with a given
103  *	alternate setting number.
104  * @intf: the interface containing the altsetting in question
105  * @altnum: the desired alternate setting number
106  *
107  * This searches the altsetting array of the specified interface for
108  * an entry with the correct bAlternateSetting value and returns a pointer
109  * to that entry, or null.
110  *
111  * Note that altsettings need not be stored sequentially by number, so
112  * it would be incorrect to assume that the first altsetting entry in
113  * the array corresponds to altsetting zero.  This routine helps device
114  * drivers avoid such mistakes.
115  *
116  * Don't call this function unless you are bound to the intf interface
117  * or you have locked the device!
118  */
119 struct usb_host_interface *usb_altnum_to_altsetting(
120 					const struct usb_interface *intf,
121 					unsigned int altnum)
122 {
123 	int i;
124 
125 	for (i = 0; i < intf->num_altsetting; i++) {
126 		if (intf->altsetting[i].desc.bAlternateSetting == altnum)
127 			return &intf->altsetting[i];
128 	}
129 	return NULL;
130 }
131 EXPORT_SYMBOL_GPL(usb_altnum_to_altsetting);
132 
133 struct find_interface_arg {
134 	int minor;
135 	struct usb_interface *interface;
136 };
137 
138 static int __find_interface(struct device *dev, void *data)
139 {
140 	struct find_interface_arg *arg = data;
141 	struct usb_interface *intf;
142 
143 	/* can't look at usb devices, only interfaces */
144 	if (is_usb_device(dev))
145 		return 0;
146 
147 	intf = to_usb_interface(dev);
148 	if (intf->minor != -1 && intf->minor == arg->minor) {
149 		arg->interface = intf;
150 		return 1;
151 	}
152 	return 0;
153 }
154 
155 /**
156  * usb_find_interface - find usb_interface pointer for driver and device
157  * @drv: the driver whose current configuration is considered
158  * @minor: the minor number of the desired device
159  *
160  * This walks the driver device list and returns a pointer to the interface
161  * with the matching minor.  Note, this only works for devices that share the
162  * USB major number.
163  */
164 struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
165 {
166 	struct find_interface_arg argb;
167 	int retval;
168 
169 	argb.minor = minor;
170 	argb.interface = NULL;
171 	/* eat the error, it will be in argb.interface */
172 	retval = driver_for_each_device(&drv->drvwrap.driver, NULL, &argb,
173 					__find_interface);
174 	return argb.interface;
175 }
176 EXPORT_SYMBOL_GPL(usb_find_interface);
177 
178 /**
179  * usb_release_dev - free a usb device structure when all users of it are finished.
180  * @dev: device that's been disconnected
181  *
182  * Will be called only by the device core when all users of this usb device are
183  * done.
184  */
185 static void usb_release_dev(struct device *dev)
186 {
187 	struct usb_device *udev;
188 
189 	udev = to_usb_device(dev);
190 
191 	usb_destroy_configuration(udev);
192 	usb_put_hcd(bus_to_hcd(udev->bus));
193 	kfree(udev->product);
194 	kfree(udev->manufacturer);
195 	kfree(udev->serial);
196 	kfree(udev);
197 }
198 
199 #ifdef	CONFIG_HOTPLUG
200 static int usb_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
201 {
202 	struct usb_device *usb_dev;
203 
204 	usb_dev = to_usb_device(dev);
205 
206 	if (add_uevent_var(env, "BUSNUM=%03d", usb_dev->bus->busnum))
207 		return -ENOMEM;
208 
209 	if (add_uevent_var(env, "DEVNUM=%03d", usb_dev->devnum))
210 		return -ENOMEM;
211 
212 	return 0;
213 }
214 
215 #else
216 
217 static int usb_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
218 {
219 	return -ENODEV;
220 }
221 #endif	/* CONFIG_HOTPLUG */
222 
223 struct device_type usb_device_type = {
224 	.name =		"usb_device",
225 	.release =	usb_release_dev,
226 	.uevent =	usb_dev_uevent,
227 };
228 
229 #ifdef	CONFIG_PM
230 
231 static int ksuspend_usb_init(void)
232 {
233 	/* This workqueue is supposed to be both freezable and
234 	 * singlethreaded.  Its job doesn't justify running on more
235 	 * than one CPU.
236 	 */
237 	ksuspend_usb_wq = create_singlethread_workqueue("ksuspend_usbd");
238 	if (!ksuspend_usb_wq)
239 		return -ENOMEM;
240 	return 0;
241 }
242 
243 static void ksuspend_usb_cleanup(void)
244 {
245 	destroy_workqueue(ksuspend_usb_wq);
246 }
247 
248 #else
249 
250 #define ksuspend_usb_init()	0
251 #define ksuspend_usb_cleanup()	do {} while (0)
252 
253 #endif	/* CONFIG_PM */
254 
255 
256 /* Returns 1 if @usb_bus is WUSB, 0 otherwise */
257 static unsigned usb_bus_is_wusb(struct usb_bus *bus)
258 {
259 	struct usb_hcd *hcd = container_of(bus, struct usb_hcd, self);
260 	return hcd->wireless;
261 }
262 
263 
264 /**
265  * usb_alloc_dev - usb device constructor (usbcore-internal)
266  * @parent: hub to which device is connected; null to allocate a root hub
267  * @bus: bus used to access the device
268  * @port1: one-based index of port; ignored for root hubs
269  * Context: !in_interrupt()
270  *
271  * Only hub drivers (including virtual root hub drivers for host
272  * controllers) should ever call this.
273  *
274  * This call may not be used in a non-sleeping context.
275  */
276 struct usb_device *usb_alloc_dev(struct usb_device *parent,
277 				 struct usb_bus *bus, unsigned port1)
278 {
279 	struct usb_device *dev;
280 	struct usb_hcd *usb_hcd = container_of(bus, struct usb_hcd, self);
281 	unsigned root_hub = 0;
282 
283 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
284 	if (!dev)
285 		return NULL;
286 
287 	if (!usb_get_hcd(bus_to_hcd(bus))) {
288 		kfree(dev);
289 		return NULL;
290 	}
291 
292 	device_initialize(&dev->dev);
293 	dev->dev.bus = &usb_bus_type;
294 	dev->dev.type = &usb_device_type;
295 	dev->dev.dma_mask = bus->controller->dma_mask;
296 	set_dev_node(&dev->dev, dev_to_node(bus->controller));
297 	dev->state = USB_STATE_ATTACHED;
298 	atomic_set(&dev->urbnum, 0);
299 
300 	INIT_LIST_HEAD(&dev->ep0.urb_list);
301 	dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
302 	dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
303 	/* ep0 maxpacket comes later, from device descriptor */
304 	usb_enable_endpoint(dev, &dev->ep0);
305 	dev->can_submit = 1;
306 
307 	/* Save readable and stable topology id, distinguishing devices
308 	 * by location for diagnostics, tools, driver model, etc.  The
309 	 * string is a path along hub ports, from the root.  Each device's
310 	 * dev->devpath will be stable until USB is re-cabled, and hubs
311 	 * are often labeled with these port numbers.  The bus_id isn't
312 	 * as stable:  bus->busnum changes easily from modprobe order,
313 	 * cardbus or pci hotplugging, and so on.
314 	 */
315 	if (unlikely(!parent)) {
316 		dev->devpath[0] = '0';
317 
318 		dev->dev.parent = bus->controller;
319 		sprintf(&dev->dev.bus_id[0], "usb%d", bus->busnum);
320 		root_hub = 1;
321 	} else {
322 		/* match any labeling on the hubs; it's one-based */
323 		if (parent->devpath[0] == '0')
324 			snprintf(dev->devpath, sizeof dev->devpath,
325 				"%d", port1);
326 		else
327 			snprintf(dev->devpath, sizeof dev->devpath,
328 				"%s.%d", parent->devpath, port1);
329 
330 		dev->dev.parent = &parent->dev;
331 		sprintf(&dev->dev.bus_id[0], "%d-%s",
332 			bus->busnum, dev->devpath);
333 
334 		/* hub driver sets up TT records */
335 	}
336 
337 	dev->portnum = port1;
338 	dev->bus = bus;
339 	dev->parent = parent;
340 	INIT_LIST_HEAD(&dev->filelist);
341 
342 #ifdef	CONFIG_PM
343 	mutex_init(&dev->pm_mutex);
344 	INIT_DELAYED_WORK(&dev->autosuspend, usb_autosuspend_work);
345 	dev->autosuspend_delay = usb_autosuspend_delay * HZ;
346 	dev->connect_time = jiffies;
347 	dev->active_duration = -jiffies;
348 #endif
349 	if (root_hub)	/* Root hub always ok [and always wired] */
350 		dev->authorized = 1;
351 	else {
352 		dev->authorized = usb_hcd->authorized_default;
353 		dev->wusb = usb_bus_is_wusb(bus)? 1 : 0;
354 	}
355 	return dev;
356 }
357 
358 /**
359  * usb_get_dev - increments the reference count of the usb device structure
360  * @dev: the device being referenced
361  *
362  * Each live reference to a device should be refcounted.
363  *
364  * Drivers for USB interfaces should normally record such references in
365  * their probe() methods, when they bind to an interface, and release
366  * them by calling usb_put_dev(), in their disconnect() methods.
367  *
368  * A pointer to the device with the incremented reference counter is returned.
369  */
370 struct usb_device *usb_get_dev(struct usb_device *dev)
371 {
372 	if (dev)
373 		get_device(&dev->dev);
374 	return dev;
375 }
376 EXPORT_SYMBOL_GPL(usb_get_dev);
377 
378 /**
379  * usb_put_dev - release a use of the usb device structure
380  * @dev: device that's been disconnected
381  *
382  * Must be called when a user of a device is finished with it.  When the last
383  * user of the device calls this function, the memory of the device is freed.
384  */
385 void usb_put_dev(struct usb_device *dev)
386 {
387 	if (dev)
388 		put_device(&dev->dev);
389 }
390 EXPORT_SYMBOL_GPL(usb_put_dev);
391 
392 /**
393  * usb_get_intf - increments the reference count of the usb interface structure
394  * @intf: the interface being referenced
395  *
396  * Each live reference to a interface must be refcounted.
397  *
398  * Drivers for USB interfaces should normally record such references in
399  * their probe() methods, when they bind to an interface, and release
400  * them by calling usb_put_intf(), in their disconnect() methods.
401  *
402  * A pointer to the interface with the incremented reference counter is
403  * returned.
404  */
405 struct usb_interface *usb_get_intf(struct usb_interface *intf)
406 {
407 	if (intf)
408 		get_device(&intf->dev);
409 	return intf;
410 }
411 EXPORT_SYMBOL_GPL(usb_get_intf);
412 
413 /**
414  * usb_put_intf - release a use of the usb interface structure
415  * @intf: interface that's been decremented
416  *
417  * Must be called when a user of an interface is finished with it.  When the
418  * last user of the interface calls this function, the memory of the interface
419  * is freed.
420  */
421 void usb_put_intf(struct usb_interface *intf)
422 {
423 	if (intf)
424 		put_device(&intf->dev);
425 }
426 EXPORT_SYMBOL_GPL(usb_put_intf);
427 
428 /*			USB device locking
429  *
430  * USB devices and interfaces are locked using the semaphore in their
431  * embedded struct device.  The hub driver guarantees that whenever a
432  * device is connected or disconnected, drivers are called with the
433  * USB device locked as well as their particular interface.
434  *
435  * Complications arise when several devices are to be locked at the same
436  * time.  Only hub-aware drivers that are part of usbcore ever have to
437  * do this; nobody else needs to worry about it.  The rule for locking
438  * is simple:
439  *
440  *	When locking both a device and its parent, always lock the
441  *	the parent first.
442  */
443 
444 /**
445  * usb_lock_device_for_reset - cautiously acquire the lock for a
446  *	usb device structure
447  * @udev: device that's being locked
448  * @iface: interface bound to the driver making the request (optional)
449  *
450  * Attempts to acquire the device lock, but fails if the device is
451  * NOTATTACHED or SUSPENDED, or if iface is specified and the interface
452  * is neither BINDING nor BOUND.  Rather than sleeping to wait for the
453  * lock, the routine polls repeatedly.  This is to prevent deadlock with
454  * disconnect; in some drivers (such as usb-storage) the disconnect()
455  * or suspend() method will block waiting for a device reset to complete.
456  *
457  * Returns a negative error code for failure, otherwise 1 or 0 to indicate
458  * that the device will or will not have to be unlocked.  (0 can be
459  * returned when an interface is given and is BINDING, because in that
460  * case the driver already owns the device lock.)
461  */
462 int usb_lock_device_for_reset(struct usb_device *udev,
463 			      const struct usb_interface *iface)
464 {
465 	unsigned long jiffies_expire = jiffies + HZ;
466 
467 	if (udev->state == USB_STATE_NOTATTACHED)
468 		return -ENODEV;
469 	if (udev->state == USB_STATE_SUSPENDED)
470 		return -EHOSTUNREACH;
471 	if (iface) {
472 		switch (iface->condition) {
473 		case USB_INTERFACE_BINDING:
474 			return 0;
475 		case USB_INTERFACE_BOUND:
476 			break;
477 		default:
478 			return -EINTR;
479 		}
480 	}
481 
482 	while (usb_trylock_device(udev) != 0) {
483 
484 		/* If we can't acquire the lock after waiting one second,
485 		 * we're probably deadlocked */
486 		if (time_after(jiffies, jiffies_expire))
487 			return -EBUSY;
488 
489 		msleep(15);
490 		if (udev->state == USB_STATE_NOTATTACHED)
491 			return -ENODEV;
492 		if (udev->state == USB_STATE_SUSPENDED)
493 			return -EHOSTUNREACH;
494 		if (iface && iface->condition != USB_INTERFACE_BOUND)
495 			return -EINTR;
496 	}
497 	return 1;
498 }
499 EXPORT_SYMBOL_GPL(usb_lock_device_for_reset);
500 
501 static struct usb_device *match_device(struct usb_device *dev,
502 				       u16 vendor_id, u16 product_id)
503 {
504 	struct usb_device *ret_dev = NULL;
505 	int child;
506 
507 	dev_dbg(&dev->dev, "check for vendor %04x, product %04x ...\n",
508 	    le16_to_cpu(dev->descriptor.idVendor),
509 	    le16_to_cpu(dev->descriptor.idProduct));
510 
511 	/* see if this device matches */
512 	if ((vendor_id == le16_to_cpu(dev->descriptor.idVendor)) &&
513 	    (product_id == le16_to_cpu(dev->descriptor.idProduct))) {
514 		dev_dbg(&dev->dev, "matched this device!\n");
515 		ret_dev = usb_get_dev(dev);
516 		goto exit;
517 	}
518 
519 	/* look through all of the children of this device */
520 	for (child = 0; child < dev->maxchild; ++child) {
521 		if (dev->children[child]) {
522 			usb_lock_device(dev->children[child]);
523 			ret_dev = match_device(dev->children[child],
524 					       vendor_id, product_id);
525 			usb_unlock_device(dev->children[child]);
526 			if (ret_dev)
527 				goto exit;
528 		}
529 	}
530 exit:
531 	return ret_dev;
532 }
533 
534 /**
535  * usb_find_device - find a specific usb device in the system
536  * @vendor_id: the vendor id of the device to find
537  * @product_id: the product id of the device to find
538  *
539  * Returns a pointer to a struct usb_device if such a specified usb
540  * device is present in the system currently.  The usage count of the
541  * device will be incremented if a device is found.  Make sure to call
542  * usb_put_dev() when the caller is finished with the device.
543  *
544  * If a device with the specified vendor and product id is not found,
545  * NULL is returned.
546  */
547 struct usb_device *usb_find_device(u16 vendor_id, u16 product_id)
548 {
549 	struct list_head *buslist;
550 	struct usb_bus *bus;
551 	struct usb_device *dev = NULL;
552 
553 	mutex_lock(&usb_bus_list_lock);
554 	for (buslist = usb_bus_list.next;
555 	     buslist != &usb_bus_list;
556 	     buslist = buslist->next) {
557 		bus = container_of(buslist, struct usb_bus, bus_list);
558 		if (!bus->root_hub)
559 			continue;
560 		usb_lock_device(bus->root_hub);
561 		dev = match_device(bus->root_hub, vendor_id, product_id);
562 		usb_unlock_device(bus->root_hub);
563 		if (dev)
564 			goto exit;
565 	}
566 exit:
567 	mutex_unlock(&usb_bus_list_lock);
568 	return dev;
569 }
570 
571 /**
572  * usb_get_current_frame_number - return current bus frame number
573  * @dev: the device whose bus is being queried
574  *
575  * Returns the current frame number for the USB host controller
576  * used with the given USB device.  This can be used when scheduling
577  * isochronous requests.
578  *
579  * Note that different kinds of host controller have different
580  * "scheduling horizons".  While one type might support scheduling only
581  * 32 frames into the future, others could support scheduling up to
582  * 1024 frames into the future.
583  */
584 int usb_get_current_frame_number(struct usb_device *dev)
585 {
586 	return usb_hcd_get_frame_number(dev);
587 }
588 EXPORT_SYMBOL_GPL(usb_get_current_frame_number);
589 
590 /*-------------------------------------------------------------------*/
591 /*
592  * __usb_get_extra_descriptor() finds a descriptor of specific type in the
593  * extra field of the interface and endpoint descriptor structs.
594  */
595 
596 int __usb_get_extra_descriptor(char *buffer, unsigned size,
597 			       unsigned char type, void **ptr)
598 {
599 	struct usb_descriptor_header *header;
600 
601 	while (size >= sizeof(struct usb_descriptor_header)) {
602 		header = (struct usb_descriptor_header *)buffer;
603 
604 		if (header->bLength < 2) {
605 			printk(KERN_ERR
606 				"%s: bogus descriptor, type %d length %d\n",
607 				usbcore_name,
608 				header->bDescriptorType,
609 				header->bLength);
610 			return -1;
611 		}
612 
613 		if (header->bDescriptorType == type) {
614 			*ptr = header;
615 			return 0;
616 		}
617 
618 		buffer += header->bLength;
619 		size -= header->bLength;
620 	}
621 	return -1;
622 }
623 EXPORT_SYMBOL_GPL(__usb_get_extra_descriptor);
624 
625 /**
626  * usb_buffer_alloc - allocate dma-consistent buffer for URB_NO_xxx_DMA_MAP
627  * @dev: device the buffer will be used with
628  * @size: requested buffer size
629  * @mem_flags: affect whether allocation may block
630  * @dma: used to return DMA address of buffer
631  *
632  * Return value is either null (indicating no buffer could be allocated), or
633  * the cpu-space pointer to a buffer that may be used to perform DMA to the
634  * specified device.  Such cpu-space buffers are returned along with the DMA
635  * address (through the pointer provided).
636  *
637  * These buffers are used with URB_NO_xxx_DMA_MAP set in urb->transfer_flags
638  * to avoid behaviors like using "DMA bounce buffers", or thrashing IOMMU
639  * hardware during URB completion/resubmit.  The implementation varies between
640  * platforms, depending on details of how DMA will work to this device.
641  * Using these buffers also eliminates cacheline sharing problems on
642  * architectures where CPU caches are not DMA-coherent.  On systems without
643  * bus-snooping caches, these buffers are uncached.
644  *
645  * When the buffer is no longer used, free it with usb_buffer_free().
646  */
647 void *usb_buffer_alloc(struct usb_device *dev, size_t size, gfp_t mem_flags,
648 		       dma_addr_t *dma)
649 {
650 	if (!dev || !dev->bus)
651 		return NULL;
652 	return hcd_buffer_alloc(dev->bus, size, mem_flags, dma);
653 }
654 EXPORT_SYMBOL_GPL(usb_buffer_alloc);
655 
656 /**
657  * usb_buffer_free - free memory allocated with usb_buffer_alloc()
658  * @dev: device the buffer was used with
659  * @size: requested buffer size
660  * @addr: CPU address of buffer
661  * @dma: DMA address of buffer
662  *
663  * This reclaims an I/O buffer, letting it be reused.  The memory must have
664  * been allocated using usb_buffer_alloc(), and the parameters must match
665  * those provided in that allocation request.
666  */
667 void usb_buffer_free(struct usb_device *dev, size_t size, void *addr,
668 		     dma_addr_t dma)
669 {
670 	if (!dev || !dev->bus)
671 		return;
672 	if (!addr)
673 		return;
674 	hcd_buffer_free(dev->bus, size, addr, dma);
675 }
676 EXPORT_SYMBOL_GPL(usb_buffer_free);
677 
678 /**
679  * usb_buffer_map - create DMA mapping(s) for an urb
680  * @urb: urb whose transfer_buffer/setup_packet will be mapped
681  *
682  * Return value is either null (indicating no buffer could be mapped), or
683  * the parameter.  URB_NO_TRANSFER_DMA_MAP and URB_NO_SETUP_DMA_MAP are
684  * added to urb->transfer_flags if the operation succeeds.  If the device
685  * is connected to this system through a non-DMA controller, this operation
686  * always succeeds.
687  *
688  * This call would normally be used for an urb which is reused, perhaps
689  * as the target of a large periodic transfer, with usb_buffer_dmasync()
690  * calls to synchronize memory and dma state.
691  *
692  * Reverse the effect of this call with usb_buffer_unmap().
693  */
694 #if 0
695 struct urb *usb_buffer_map(struct urb *urb)
696 {
697 	struct usb_bus		*bus;
698 	struct device		*controller;
699 
700 	if (!urb
701 			|| !urb->dev
702 			|| !(bus = urb->dev->bus)
703 			|| !(controller = bus->controller))
704 		return NULL;
705 
706 	if (controller->dma_mask) {
707 		urb->transfer_dma = dma_map_single(controller,
708 			urb->transfer_buffer, urb->transfer_buffer_length,
709 			usb_pipein(urb->pipe)
710 				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
711 		if (usb_pipecontrol(urb->pipe))
712 			urb->setup_dma = dma_map_single(controller,
713 					urb->setup_packet,
714 					sizeof(struct usb_ctrlrequest),
715 					DMA_TO_DEVICE);
716 	/* FIXME generic api broken like pci, can't report errors */
717 	/* if (urb->transfer_dma == DMA_ADDR_INVALID) return 0; */
718 	} else
719 		urb->transfer_dma = ~0;
720 	urb->transfer_flags |= (URB_NO_TRANSFER_DMA_MAP
721 				| URB_NO_SETUP_DMA_MAP);
722 	return urb;
723 }
724 EXPORT_SYMBOL_GPL(usb_buffer_map);
725 #endif  /*  0  */
726 
727 /* XXX DISABLED, no users currently.  If you wish to re-enable this
728  * XXX please determine whether the sync is to transfer ownership of
729  * XXX the buffer from device to cpu or vice verse, and thusly use the
730  * XXX appropriate _for_{cpu,device}() method.  -DaveM
731  */
732 #if 0
733 
734 /**
735  * usb_buffer_dmasync - synchronize DMA and CPU view of buffer(s)
736  * @urb: urb whose transfer_buffer/setup_packet will be synchronized
737  */
738 void usb_buffer_dmasync(struct urb *urb)
739 {
740 	struct usb_bus		*bus;
741 	struct device		*controller;
742 
743 	if (!urb
744 			|| !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
745 			|| !urb->dev
746 			|| !(bus = urb->dev->bus)
747 			|| !(controller = bus->controller))
748 		return;
749 
750 	if (controller->dma_mask) {
751 		dma_sync_single(controller,
752 			urb->transfer_dma, urb->transfer_buffer_length,
753 			usb_pipein(urb->pipe)
754 				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
755 		if (usb_pipecontrol(urb->pipe))
756 			dma_sync_single(controller,
757 					urb->setup_dma,
758 					sizeof(struct usb_ctrlrequest),
759 					DMA_TO_DEVICE);
760 	}
761 }
762 EXPORT_SYMBOL_GPL(usb_buffer_dmasync);
763 #endif
764 
765 /**
766  * usb_buffer_unmap - free DMA mapping(s) for an urb
767  * @urb: urb whose transfer_buffer will be unmapped
768  *
769  * Reverses the effect of usb_buffer_map().
770  */
771 #if 0
772 void usb_buffer_unmap(struct urb *urb)
773 {
774 	struct usb_bus		*bus;
775 	struct device		*controller;
776 
777 	if (!urb
778 			|| !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
779 			|| !urb->dev
780 			|| !(bus = urb->dev->bus)
781 			|| !(controller = bus->controller))
782 		return;
783 
784 	if (controller->dma_mask) {
785 		dma_unmap_single(controller,
786 			urb->transfer_dma, urb->transfer_buffer_length,
787 			usb_pipein(urb->pipe)
788 				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
789 		if (usb_pipecontrol(urb->pipe))
790 			dma_unmap_single(controller,
791 					urb->setup_dma,
792 					sizeof(struct usb_ctrlrequest),
793 					DMA_TO_DEVICE);
794 	}
795 	urb->transfer_flags &= ~(URB_NO_TRANSFER_DMA_MAP
796 				| URB_NO_SETUP_DMA_MAP);
797 }
798 EXPORT_SYMBOL_GPL(usb_buffer_unmap);
799 #endif  /*  0  */
800 
801 /**
802  * usb_buffer_map_sg - create scatterlist DMA mapping(s) for an endpoint
803  * @dev: device to which the scatterlist will be mapped
804  * @is_in: mapping transfer direction
805  * @sg: the scatterlist to map
806  * @nents: the number of entries in the scatterlist
807  *
808  * Return value is either < 0 (indicating no buffers could be mapped), or
809  * the number of DMA mapping array entries in the scatterlist.
810  *
811  * The caller is responsible for placing the resulting DMA addresses from
812  * the scatterlist into URB transfer buffer pointers, and for setting the
813  * URB_NO_TRANSFER_DMA_MAP transfer flag in each of those URBs.
814  *
815  * Top I/O rates come from queuing URBs, instead of waiting for each one
816  * to complete before starting the next I/O.   This is particularly easy
817  * to do with scatterlists.  Just allocate and submit one URB for each DMA
818  * mapping entry returned, stopping on the first error or when all succeed.
819  * Better yet, use the usb_sg_*() calls, which do that (and more) for you.
820  *
821  * This call would normally be used when translating scatterlist requests,
822  * rather than usb_buffer_map(), since on some hardware (with IOMMUs) it
823  * may be able to coalesce mappings for improved I/O efficiency.
824  *
825  * Reverse the effect of this call with usb_buffer_unmap_sg().
826  */
827 int usb_buffer_map_sg(const struct usb_device *dev, int is_in,
828 		      struct scatterlist *sg, int nents)
829 {
830 	struct usb_bus		*bus;
831 	struct device		*controller;
832 
833 	if (!dev
834 			|| !(bus = dev->bus)
835 			|| !(controller = bus->controller)
836 			|| !controller->dma_mask)
837 		return -1;
838 
839 	/* FIXME generic api broken like pci, can't report errors */
840 	return dma_map_sg(controller, sg, nents,
841 			is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
842 }
843 EXPORT_SYMBOL_GPL(usb_buffer_map_sg);
844 
845 /* XXX DISABLED, no users currently.  If you wish to re-enable this
846  * XXX please determine whether the sync is to transfer ownership of
847  * XXX the buffer from device to cpu or vice verse, and thusly use the
848  * XXX appropriate _for_{cpu,device}() method.  -DaveM
849  */
850 #if 0
851 
852 /**
853  * usb_buffer_dmasync_sg - synchronize DMA and CPU view of scatterlist buffer(s)
854  * @dev: device to which the scatterlist will be mapped
855  * @is_in: mapping transfer direction
856  * @sg: the scatterlist to synchronize
857  * @n_hw_ents: the positive return value from usb_buffer_map_sg
858  *
859  * Use this when you are re-using a scatterlist's data buffers for
860  * another USB request.
861  */
862 void usb_buffer_dmasync_sg(const struct usb_device *dev, int is_in,
863 			   struct scatterlist *sg, int n_hw_ents)
864 {
865 	struct usb_bus		*bus;
866 	struct device		*controller;
867 
868 	if (!dev
869 			|| !(bus = dev->bus)
870 			|| !(controller = bus->controller)
871 			|| !controller->dma_mask)
872 		return;
873 
874 	dma_sync_sg(controller, sg, n_hw_ents,
875 			is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
876 }
877 EXPORT_SYMBOL_GPL(usb_buffer_dmasync_sg);
878 #endif
879 
880 /**
881  * usb_buffer_unmap_sg - free DMA mapping(s) for a scatterlist
882  * @dev: device to which the scatterlist will be mapped
883  * @is_in: mapping transfer direction
884  * @sg: the scatterlist to unmap
885  * @n_hw_ents: the positive return value from usb_buffer_map_sg
886  *
887  * Reverses the effect of usb_buffer_map_sg().
888  */
889 void usb_buffer_unmap_sg(const struct usb_device *dev, int is_in,
890 			 struct scatterlist *sg, int n_hw_ents)
891 {
892 	struct usb_bus		*bus;
893 	struct device		*controller;
894 
895 	if (!dev
896 			|| !(bus = dev->bus)
897 			|| !(controller = bus->controller)
898 			|| !controller->dma_mask)
899 		return;
900 
901 	dma_unmap_sg(controller, sg, n_hw_ents,
902 			is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
903 }
904 EXPORT_SYMBOL_GPL(usb_buffer_unmap_sg);
905 
906 /* format to disable USB on kernel command line is: nousb */
907 __module_param_call("", nousb, param_set_bool, param_get_bool, &nousb, 0444);
908 
909 /*
910  * for external read access to <nousb>
911  */
912 int usb_disabled(void)
913 {
914 	return nousb;
915 }
916 EXPORT_SYMBOL_GPL(usb_disabled);
917 
918 /*
919  * Init
920  */
921 static int __init usb_init(void)
922 {
923 	int retval;
924 	if (nousb) {
925 		pr_info("%s: USB support disabled\n", usbcore_name);
926 		return 0;
927 	}
928 
929 	retval = ksuspend_usb_init();
930 	if (retval)
931 		goto out;
932 	retval = bus_register(&usb_bus_type);
933 	if (retval)
934 		goto bus_register_failed;
935 	retval = usb_host_init();
936 	if (retval)
937 		goto host_init_failed;
938 	retval = usb_major_init();
939 	if (retval)
940 		goto major_init_failed;
941 	retval = usb_register(&usbfs_driver);
942 	if (retval)
943 		goto driver_register_failed;
944 	retval = usb_devio_init();
945 	if (retval)
946 		goto usb_devio_init_failed;
947 	retval = usbfs_init();
948 	if (retval)
949 		goto fs_init_failed;
950 	retval = usb_hub_init();
951 	if (retval)
952 		goto hub_init_failed;
953 	retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
954 	if (!retval)
955 		goto out;
956 
957 	usb_hub_cleanup();
958 hub_init_failed:
959 	usbfs_cleanup();
960 fs_init_failed:
961 	usb_devio_cleanup();
962 usb_devio_init_failed:
963 	usb_deregister(&usbfs_driver);
964 driver_register_failed:
965 	usb_major_cleanup();
966 major_init_failed:
967 	usb_host_cleanup();
968 host_init_failed:
969 	bus_unregister(&usb_bus_type);
970 bus_register_failed:
971 	ksuspend_usb_cleanup();
972 out:
973 	return retval;
974 }
975 
976 /*
977  * Cleanup
978  */
979 static void __exit usb_exit(void)
980 {
981 	/* This will matter if shutdown/reboot does exitcalls. */
982 	if (nousb)
983 		return;
984 
985 	usb_deregister_device_driver(&usb_generic_driver);
986 	usb_major_cleanup();
987 	usbfs_cleanup();
988 	usb_deregister(&usbfs_driver);
989 	usb_devio_cleanup();
990 	usb_hub_cleanup();
991 	usb_host_cleanup();
992 	bus_unregister(&usb_bus_type);
993 	ksuspend_usb_cleanup();
994 }
995 
996 subsys_initcall(usb_init);
997 module_exit(usb_exit);
998 MODULE_LICENSE("GPL");
999