1 // SPDX-License-Identifier: GPL-2.0
3 * drivers/usb/core/usb.c
5 * (C) Copyright Linus Torvalds 1999
6 * (C) Copyright Johannes Erdfelt 1999-2001
7 * (C) Copyright Andreas Gal 1999
8 * (C) Copyright Gregory P. Smith 1999
9 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
10 * (C) Copyright Randy Dunlap 2000
11 * (C) Copyright David Brownell 2000-2004
12 * (C) Copyright Yggdrasil Computing, Inc. 2000
13 * (usb_device_id matching changes by Adam J. Richter)
14 * (C) Copyright Greg Kroah-Hartman 2002-2003
16 * Released under the GPLv2 only.
18 * NOTE! This is not actually a driver at all, rather this is
19 * just a collection of helper routines that implement the
20 * generic USB things that the real drivers can use..
22 * Think of this as a "USB library" rather than anything else,
23 * with no callbacks. Callbacks are evil.
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/string.h>
29 #include <linux/bitops.h>
30 #include <linux/slab.h>
31 #include <linux/interrupt.h> /* for in_interrupt() */
32 #include <linux/kmod.h>
33 #include <linux/init.h>
34 #include <linux/spinlock.h>
35 #include <linux/errno.h>
36 #include <linux/usb.h>
37 #include <linux/usb/hcd.h>
38 #include <linux/mutex.h>
39 #include <linux/workqueue.h>
40 #include <linux/debugfs.h>
41 #include <linux/usb/of.h>
44 #include <linux/scatterlist.h>
46 #include <linux/dma-mapping.h>
50 const char *usbcore_name = "usbcore";
52 static bool nousb; /* Disable USB when built into kernel image */
54 module_param(nousb, bool, 0444);
57 * for external read access to <nousb>
59 int usb_disabled(void)
63 EXPORT_SYMBOL_GPL(usb_disabled);
66 /* Default delay value, in seconds */
67 static int usb_autosuspend_delay = CONFIG_USB_AUTOSUSPEND_DELAY;
68 module_param_named(autosuspend, usb_autosuspend_delay, int, 0644);
69 MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
72 #define usb_autosuspend_delay 0
75 static bool match_endpoint(struct usb_endpoint_descriptor *epd,
76 struct usb_endpoint_descriptor **bulk_in,
77 struct usb_endpoint_descriptor **bulk_out,
78 struct usb_endpoint_descriptor **int_in,
79 struct usb_endpoint_descriptor **int_out)
81 switch (usb_endpoint_type(epd)) {
82 case USB_ENDPOINT_XFER_BULK:
83 if (usb_endpoint_dir_in(epd)) {
84 if (bulk_in && !*bulk_in) {
89 if (bulk_out && !*bulk_out) {
96 case USB_ENDPOINT_XFER_INT:
97 if (usb_endpoint_dir_in(epd)) {
98 if (int_in && !*int_in) {
103 if (int_out && !*int_out) {
114 return (!bulk_in || *bulk_in) && (!bulk_out || *bulk_out) &&
115 (!int_in || *int_in) && (!int_out || *int_out);
119 * usb_find_common_endpoints() -- look up common endpoint descriptors
120 * @alt: alternate setting to search
121 * @bulk_in: pointer to descriptor pointer, or NULL
122 * @bulk_out: pointer to descriptor pointer, or NULL
123 * @int_in: pointer to descriptor pointer, or NULL
124 * @int_out: pointer to descriptor pointer, or NULL
126 * Search the alternate setting's endpoint descriptors for the first bulk-in,
127 * bulk-out, interrupt-in and interrupt-out endpoints and return them in the
128 * provided pointers (unless they are NULL).
130 * If a requested endpoint is not found, the corresponding pointer is set to
133 * Return: Zero if all requested descriptors were found, or -ENXIO otherwise.
135 int usb_find_common_endpoints(struct usb_host_interface *alt,
136 struct usb_endpoint_descriptor **bulk_in,
137 struct usb_endpoint_descriptor **bulk_out,
138 struct usb_endpoint_descriptor **int_in,
139 struct usb_endpoint_descriptor **int_out)
141 struct usb_endpoint_descriptor *epd;
153 for (i = 0; i < alt->desc.bNumEndpoints; ++i) {
154 epd = &alt->endpoint[i].desc;
156 if (match_endpoint(epd, bulk_in, bulk_out, int_in, int_out))
162 EXPORT_SYMBOL_GPL(usb_find_common_endpoints);
165 * usb_find_common_endpoints_reverse() -- look up common endpoint descriptors
166 * @alt: alternate setting to search
167 * @bulk_in: pointer to descriptor pointer, or NULL
168 * @bulk_out: pointer to descriptor pointer, or NULL
169 * @int_in: pointer to descriptor pointer, or NULL
170 * @int_out: pointer to descriptor pointer, or NULL
172 * Search the alternate setting's endpoint descriptors for the last bulk-in,
173 * bulk-out, interrupt-in and interrupt-out endpoints and return them in the
174 * provided pointers (unless they are NULL).
176 * If a requested endpoint is not found, the corresponding pointer is set to
179 * Return: Zero if all requested descriptors were found, or -ENXIO otherwise.
181 int usb_find_common_endpoints_reverse(struct usb_host_interface *alt,
182 struct usb_endpoint_descriptor **bulk_in,
183 struct usb_endpoint_descriptor **bulk_out,
184 struct usb_endpoint_descriptor **int_in,
185 struct usb_endpoint_descriptor **int_out)
187 struct usb_endpoint_descriptor *epd;
199 for (i = alt->desc.bNumEndpoints - 1; i >= 0; --i) {
200 epd = &alt->endpoint[i].desc;
202 if (match_endpoint(epd, bulk_in, bulk_out, int_in, int_out))
208 EXPORT_SYMBOL_GPL(usb_find_common_endpoints_reverse);
211 * usb_find_endpoint() - Given an endpoint address, search for the endpoint's
212 * usb_host_endpoint structure in an interface's current altsetting.
213 * @intf: the interface whose current altsetting should be searched
214 * @ep_addr: the endpoint address (number and direction) to find
216 * Search the altsetting's list of endpoints for one with the specified address.
218 * Return: Pointer to the usb_host_endpoint if found, %NULL otherwise.
220 static const struct usb_host_endpoint *usb_find_endpoint(
221 const struct usb_interface *intf, unsigned int ep_addr)
224 const struct usb_host_endpoint *ep;
226 n = intf->cur_altsetting->desc.bNumEndpoints;
227 ep = intf->cur_altsetting->endpoint;
228 for (; n > 0; (--n, ++ep)) {
229 if (ep->desc.bEndpointAddress == ep_addr)
236 * usb_check_bulk_endpoints - Check whether an interface's current altsetting
237 * contains a set of bulk endpoints with the given addresses.
238 * @intf: the interface whose current altsetting should be searched
239 * @ep_addrs: 0-terminated array of the endpoint addresses (number and
240 * direction) to look for
242 * Search for endpoints with the specified addresses and check their types.
244 * Return: %true if all the endpoints are found and are bulk, %false otherwise.
246 bool usb_check_bulk_endpoints(
247 const struct usb_interface *intf, const u8 *ep_addrs)
249 const struct usb_host_endpoint *ep;
251 for (; *ep_addrs; ++ep_addrs) {
252 ep = usb_find_endpoint(intf, *ep_addrs);
253 if (!ep || !usb_endpoint_xfer_bulk(&ep->desc))
258 EXPORT_SYMBOL_GPL(usb_check_bulk_endpoints);
261 * usb_check_int_endpoints - Check whether an interface's current altsetting
262 * contains a set of interrupt endpoints with the given addresses.
263 * @intf: the interface whose current altsetting should be searched
264 * @ep_addrs: 0-terminated array of the endpoint addresses (number and
265 * direction) to look for
267 * Search for endpoints with the specified addresses and check their types.
269 * Return: %true if all the endpoints are found and are interrupt,
272 bool usb_check_int_endpoints(
273 const struct usb_interface *intf, const u8 *ep_addrs)
275 const struct usb_host_endpoint *ep;
277 for (; *ep_addrs; ++ep_addrs) {
278 ep = usb_find_endpoint(intf, *ep_addrs);
279 if (!ep || !usb_endpoint_xfer_int(&ep->desc))
284 EXPORT_SYMBOL_GPL(usb_check_int_endpoints);
287 * usb_find_alt_setting() - Given a configuration, find the alternate setting
288 * for the given interface.
289 * @config: the configuration to search (not necessarily the current config).
290 * @iface_num: interface number to search in
291 * @alt_num: alternate interface setting number to search for.
293 * Search the configuration's interface cache for the given alt setting.
295 * Return: The alternate setting, if found. %NULL otherwise.
297 struct usb_host_interface *usb_find_alt_setting(
298 struct usb_host_config *config,
299 unsigned int iface_num,
300 unsigned int alt_num)
302 struct usb_interface_cache *intf_cache = NULL;
307 for (i = 0; i < config->desc.bNumInterfaces; i++) {
308 if (config->intf_cache[i]->altsetting[0].desc.bInterfaceNumber
310 intf_cache = config->intf_cache[i];
316 for (i = 0; i < intf_cache->num_altsetting; i++)
317 if (intf_cache->altsetting[i].desc.bAlternateSetting == alt_num)
318 return &intf_cache->altsetting[i];
320 printk(KERN_DEBUG "Did not find alt setting %u for intf %u, "
321 "config %u\n", alt_num, iface_num,
322 config->desc.bConfigurationValue);
325 EXPORT_SYMBOL_GPL(usb_find_alt_setting);
328 * usb_ifnum_to_if - get the interface object with a given interface number
329 * @dev: the device whose current configuration is considered
330 * @ifnum: the desired interface
332 * This walks the device descriptor for the currently active configuration
333 * to find the interface object with the particular interface number.
335 * Note that configuration descriptors are not required to assign interface
336 * numbers sequentially, so that it would be incorrect to assume that
337 * the first interface in that descriptor corresponds to interface zero.
338 * This routine helps device drivers avoid such mistakes.
339 * However, you should make sure that you do the right thing with any
340 * alternate settings available for this interfaces.
342 * Don't call this function unless you are bound to one of the interfaces
343 * on this device or you have locked the device!
345 * Return: A pointer to the interface that has @ifnum as interface number,
346 * if found. %NULL otherwise.
348 struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev,
351 struct usb_host_config *config = dev->actconfig;
356 for (i = 0; i < config->desc.bNumInterfaces; i++)
357 if (config->interface[i]->altsetting[0]
358 .desc.bInterfaceNumber == ifnum)
359 return config->interface[i];
363 EXPORT_SYMBOL_GPL(usb_ifnum_to_if);
366 * usb_altnum_to_altsetting - get the altsetting structure with a given alternate setting number.
367 * @intf: the interface containing the altsetting in question
368 * @altnum: the desired alternate setting number
370 * This searches the altsetting array of the specified interface for
371 * an entry with the correct bAlternateSetting value.
373 * Note that altsettings need not be stored sequentially by number, so
374 * it would be incorrect to assume that the first altsetting entry in
375 * the array corresponds to altsetting zero. This routine helps device
376 * drivers avoid such mistakes.
378 * Don't call this function unless you are bound to the intf interface
379 * or you have locked the device!
381 * Return: A pointer to the entry of the altsetting array of @intf that
382 * has @altnum as the alternate setting number. %NULL if not found.
384 struct usb_host_interface *usb_altnum_to_altsetting(
385 const struct usb_interface *intf,
390 for (i = 0; i < intf->num_altsetting; i++) {
391 if (intf->altsetting[i].desc.bAlternateSetting == altnum)
392 return &intf->altsetting[i];
396 EXPORT_SYMBOL_GPL(usb_altnum_to_altsetting);
398 struct find_interface_arg {
400 struct device_driver *drv;
403 static int __find_interface(struct device *dev, const void *data)
405 const struct find_interface_arg *arg = data;
406 struct usb_interface *intf;
408 if (!is_usb_interface(dev))
411 if (dev->driver != arg->drv)
413 intf = to_usb_interface(dev);
414 return intf->minor == arg->minor;
418 * usb_find_interface - find usb_interface pointer for driver and device
419 * @drv: the driver whose current configuration is considered
420 * @minor: the minor number of the desired device
422 * This walks the bus device list and returns a pointer to the interface
423 * with the matching minor and driver. Note, this only works for devices
424 * that share the USB major number.
426 * Return: A pointer to the interface with the matching major and @minor.
428 struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
430 struct find_interface_arg argb;
434 argb.drv = &drv->drvwrap.driver;
436 dev = bus_find_device(&usb_bus_type, NULL, &argb, __find_interface);
438 /* Drop reference count from bus_find_device */
441 return dev ? to_usb_interface(dev) : NULL;
443 EXPORT_SYMBOL_GPL(usb_find_interface);
445 struct each_dev_arg {
447 int (*fn)(struct usb_device *, void *);
450 static int __each_dev(struct device *dev, void *data)
452 struct each_dev_arg *arg = (struct each_dev_arg *)data;
454 /* There are struct usb_interface on the same bus, filter them out */
455 if (!is_usb_device(dev))
458 return arg->fn(to_usb_device(dev), arg->data);
462 * usb_for_each_dev - iterate over all USB devices in the system
463 * @data: data pointer that will be handed to the callback function
464 * @fn: callback function to be called for each USB device
466 * Iterate over all USB devices and call @fn for each, passing it @data. If it
467 * returns anything other than 0, we break the iteration prematurely and return
470 int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
472 struct each_dev_arg arg = {data, fn};
474 return bus_for_each_dev(&usb_bus_type, NULL, &arg, __each_dev);
476 EXPORT_SYMBOL_GPL(usb_for_each_dev);
479 * usb_release_dev - free a usb device structure when all users of it are finished.
480 * @dev: device that's been disconnected
482 * Will be called only by the device core when all users of this usb device are
485 static void usb_release_dev(struct device *dev)
487 struct usb_device *udev;
490 udev = to_usb_device(dev);
491 hcd = bus_to_hcd(udev->bus);
493 usb_destroy_configuration(udev);
494 usb_release_bos_descriptor(udev);
495 of_node_put(dev->of_node);
497 kfree(udev->product);
498 kfree(udev->manufacturer);
503 static int usb_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
505 struct usb_device *usb_dev;
507 usb_dev = to_usb_device(dev);
509 if (add_uevent_var(env, "BUSNUM=%03d", usb_dev->bus->busnum))
512 if (add_uevent_var(env, "DEVNUM=%03d", usb_dev->devnum))
520 /* USB device Power-Management thunks.
521 * There's no need to distinguish here between quiescing a USB device
522 * and powering it down; the generic_suspend() routine takes care of
523 * it by skipping the usb_port_suspend() call for a quiesce. And for
524 * USB interfaces there's no difference at all.
527 static int usb_dev_prepare(struct device *dev)
529 return 0; /* Implement eventually? */
532 static void usb_dev_complete(struct device *dev)
534 /* Currently used only for rebinding interfaces */
535 usb_resume_complete(dev);
538 static int usb_dev_suspend(struct device *dev)
540 return usb_suspend(dev, PMSG_SUSPEND);
543 static int usb_dev_resume(struct device *dev)
545 return usb_resume(dev, PMSG_RESUME);
548 static int usb_dev_freeze(struct device *dev)
550 return usb_suspend(dev, PMSG_FREEZE);
553 static int usb_dev_thaw(struct device *dev)
555 return usb_resume(dev, PMSG_THAW);
558 static int usb_dev_poweroff(struct device *dev)
560 return usb_suspend(dev, PMSG_HIBERNATE);
563 static int usb_dev_restore(struct device *dev)
565 return usb_resume(dev, PMSG_RESTORE);
568 static const struct dev_pm_ops usb_device_pm_ops = {
569 .prepare = usb_dev_prepare,
570 .complete = usb_dev_complete,
571 .suspend = usb_dev_suspend,
572 .resume = usb_dev_resume,
573 .freeze = usb_dev_freeze,
574 .thaw = usb_dev_thaw,
575 .poweroff = usb_dev_poweroff,
576 .restore = usb_dev_restore,
577 .runtime_suspend = usb_runtime_suspend,
578 .runtime_resume = usb_runtime_resume,
579 .runtime_idle = usb_runtime_idle,
582 #endif /* CONFIG_PM */
585 static char *usb_devnode(struct device *dev,
586 umode_t *mode, kuid_t *uid, kgid_t *gid)
588 struct usb_device *usb_dev;
590 usb_dev = to_usb_device(dev);
591 return kasprintf(GFP_KERNEL, "bus/usb/%03d/%03d",
592 usb_dev->bus->busnum, usb_dev->devnum);
595 struct device_type usb_device_type = {
596 .name = "usb_device",
597 .release = usb_release_dev,
598 .uevent = usb_dev_uevent,
599 .devnode = usb_devnode,
601 .pm = &usb_device_pm_ops,
606 /* Returns 1 if @usb_bus is WUSB, 0 otherwise */
607 static unsigned usb_bus_is_wusb(struct usb_bus *bus)
609 struct usb_hcd *hcd = bus_to_hcd(bus);
610 return hcd->wireless;
613 static bool usb_dev_authorized(struct usb_device *dev, struct usb_hcd *hcd)
618 return true; /* Root hub always ok [and always wired] */
620 switch (hcd->dev_policy) {
621 case USB_DEVICE_AUTHORIZE_NONE:
625 case USB_DEVICE_AUTHORIZE_ALL:
628 case USB_DEVICE_AUTHORIZE_INTERNAL:
629 hub = usb_hub_to_struct_hub(dev->parent);
630 return hub->ports[dev->portnum - 1]->connect_type ==
631 USB_PORT_CONNECT_TYPE_HARD_WIRED;
636 * usb_alloc_dev - usb device constructor (usbcore-internal)
637 * @parent: hub to which device is connected; null to allocate a root hub
638 * @bus: bus used to access the device
639 * @port1: one-based index of port; ignored for root hubs
640 * Context: !in_interrupt()
642 * Only hub drivers (including virtual root hub drivers for host
643 * controllers) should ever call this.
645 * This call may not be used in a non-sleeping context.
647 * Return: On success, a pointer to the allocated usb device. %NULL on
650 struct usb_device *usb_alloc_dev(struct usb_device *parent,
651 struct usb_bus *bus, unsigned port1)
653 struct usb_device *dev;
654 struct usb_hcd *usb_hcd = bus_to_hcd(bus);
655 unsigned root_hub = 0;
656 unsigned raw_port = port1;
658 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
662 if (!usb_get_hcd(usb_hcd)) {
666 /* Root hubs aren't true devices, so don't allocate HCD resources */
667 if (usb_hcd->driver->alloc_dev && parent &&
668 !usb_hcd->driver->alloc_dev(usb_hcd, dev)) {
669 usb_put_hcd(bus_to_hcd(bus));
674 device_initialize(&dev->dev);
675 dev->dev.bus = &usb_bus_type;
676 dev->dev.type = &usb_device_type;
677 dev->dev.groups = usb_device_groups;
678 set_dev_node(&dev->dev, dev_to_node(bus->sysdev));
679 dev->state = USB_STATE_ATTACHED;
680 dev->lpm_disable_count = 1;
681 atomic_set(&dev->urbnum, 0);
683 INIT_LIST_HEAD(&dev->ep0.urb_list);
684 dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
685 dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
686 /* ep0 maxpacket comes later, from device descriptor */
687 usb_enable_endpoint(dev, &dev->ep0, false);
690 /* Save readable and stable topology id, distinguishing devices
691 * by location for diagnostics, tools, driver model, etc. The
692 * string is a path along hub ports, from the root. Each device's
693 * dev->devpath will be stable until USB is re-cabled, and hubs
694 * are often labeled with these port numbers. The name isn't
695 * as stable: bus->busnum changes easily from modprobe order,
696 * cardbus or pci hotplugging, and so on.
698 if (unlikely(!parent)) {
699 dev->devpath[0] = '0';
702 dev->dev.parent = bus->controller;
703 device_set_of_node_from_dev(&dev->dev, bus->sysdev);
704 dev_set_name(&dev->dev, "usb%d", bus->busnum);
707 /* match any labeling on the hubs; it's one-based */
708 if (parent->devpath[0] == '0') {
709 snprintf(dev->devpath, sizeof dev->devpath,
711 /* Root ports are not counted in route string */
714 snprintf(dev->devpath, sizeof dev->devpath,
715 "%s.%d", parent->devpath, port1);
716 /* Route string assumes hubs have less than 16 ports */
718 dev->route = parent->route +
719 (port1 << ((parent->level - 1)*4));
721 dev->route = parent->route +
722 (15 << ((parent->level - 1)*4));
725 dev->dev.parent = &parent->dev;
726 dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);
728 if (!parent->parent) {
729 /* device under root hub's port */
730 raw_port = usb_hcd_find_raw_port_number(usb_hcd,
733 dev->dev.of_node = usb_of_get_device_node(parent, raw_port);
735 /* hub driver sets up TT records */
738 dev->portnum = port1;
740 dev->parent = parent;
741 INIT_LIST_HEAD(&dev->filelist);
744 pm_runtime_set_autosuspend_delay(&dev->dev,
745 usb_autosuspend_delay * 1000);
746 dev->connect_time = jiffies;
747 dev->active_duration = -jiffies;
750 dev->authorized = usb_dev_authorized(dev, usb_hcd);
752 dev->wusb = usb_bus_is_wusb(bus) ? 1 : 0;
756 EXPORT_SYMBOL_GPL(usb_alloc_dev);
759 * usb_get_dev - increments the reference count of the usb device structure
760 * @dev: the device being referenced
762 * Each live reference to a device should be refcounted.
764 * Drivers for USB interfaces should normally record such references in
765 * their probe() methods, when they bind to an interface, and release
766 * them by calling usb_put_dev(), in their disconnect() methods.
768 * Return: A pointer to the device with the incremented reference counter.
770 struct usb_device *usb_get_dev(struct usb_device *dev)
773 get_device(&dev->dev);
776 EXPORT_SYMBOL_GPL(usb_get_dev);
779 * usb_put_dev - release a use of the usb device structure
780 * @dev: device that's been disconnected
782 * Must be called when a user of a device is finished with it. When the last
783 * user of the device calls this function, the memory of the device is freed.
785 void usb_put_dev(struct usb_device *dev)
788 put_device(&dev->dev);
790 EXPORT_SYMBOL_GPL(usb_put_dev);
793 * usb_get_intf - increments the reference count of the usb interface structure
794 * @intf: the interface being referenced
796 * Each live reference to a interface must be refcounted.
798 * Drivers for USB interfaces should normally record such references in
799 * their probe() methods, when they bind to an interface, and release
800 * them by calling usb_put_intf(), in their disconnect() methods.
802 * Return: A pointer to the interface with the incremented reference counter.
804 struct usb_interface *usb_get_intf(struct usb_interface *intf)
807 get_device(&intf->dev);
810 EXPORT_SYMBOL_GPL(usb_get_intf);
813 * usb_put_intf - release a use of the usb interface structure
814 * @intf: interface that's been decremented
816 * Must be called when a user of an interface is finished with it. When the
817 * last user of the interface calls this function, the memory of the interface
820 void usb_put_intf(struct usb_interface *intf)
823 put_device(&intf->dev);
825 EXPORT_SYMBOL_GPL(usb_put_intf);
828 * usb_intf_get_dma_device - acquire a reference on the usb interface's DMA endpoint
829 * @intf: the usb interface
831 * While a USB device cannot perform DMA operations by itself, many USB
832 * controllers can. A call to usb_intf_get_dma_device() returns the DMA endpoint
833 * for the given USB interface, if any. The returned device structure must be
834 * released with put_device().
836 * See also usb_get_dma_device().
838 * Returns: A reference to the usb interface's DMA endpoint; or NULL if none
841 struct device *usb_intf_get_dma_device(struct usb_interface *intf)
843 struct usb_device *udev = interface_to_usbdev(intf);
844 struct device *dmadev;
849 dmadev = get_device(udev->bus->sysdev);
850 if (!dmadev || !dmadev->dma_mask) {
857 EXPORT_SYMBOL_GPL(usb_intf_get_dma_device);
859 /* USB device locking
861 * USB devices and interfaces are locked using the semaphore in their
862 * embedded struct device. The hub driver guarantees that whenever a
863 * device is connected or disconnected, drivers are called with the
864 * USB device locked as well as their particular interface.
866 * Complications arise when several devices are to be locked at the same
867 * time. Only hub-aware drivers that are part of usbcore ever have to
868 * do this; nobody else needs to worry about it. The rule for locking
871 * When locking both a device and its parent, always lock the
876 * usb_lock_device_for_reset - cautiously acquire the lock for a usb device structure
877 * @udev: device that's being locked
878 * @iface: interface bound to the driver making the request (optional)
880 * Attempts to acquire the device lock, but fails if the device is
881 * NOTATTACHED or SUSPENDED, or if iface is specified and the interface
882 * is neither BINDING nor BOUND. Rather than sleeping to wait for the
883 * lock, the routine polls repeatedly. This is to prevent deadlock with
884 * disconnect; in some drivers (such as usb-storage) the disconnect()
885 * or suspend() method will block waiting for a device reset to complete.
887 * Return: A negative error code for failure, otherwise 0.
889 int usb_lock_device_for_reset(struct usb_device *udev,
890 const struct usb_interface *iface)
892 unsigned long jiffies_expire = jiffies + HZ;
894 if (udev->state == USB_STATE_NOTATTACHED)
896 if (udev->state == USB_STATE_SUSPENDED)
897 return -EHOSTUNREACH;
898 if (iface && (iface->condition == USB_INTERFACE_UNBINDING ||
899 iface->condition == USB_INTERFACE_UNBOUND))
902 while (!usb_trylock_device(udev)) {
904 /* If we can't acquire the lock after waiting one second,
905 * we're probably deadlocked */
906 if (time_after(jiffies, jiffies_expire))
910 if (udev->state == USB_STATE_NOTATTACHED)
912 if (udev->state == USB_STATE_SUSPENDED)
913 return -EHOSTUNREACH;
914 if (iface && (iface->condition == USB_INTERFACE_UNBINDING ||
915 iface->condition == USB_INTERFACE_UNBOUND))
920 EXPORT_SYMBOL_GPL(usb_lock_device_for_reset);
923 * usb_get_current_frame_number - return current bus frame number
924 * @dev: the device whose bus is being queried
926 * Return: The current frame number for the USB host controller used
927 * with the given USB device. This can be used when scheduling
928 * isochronous requests.
930 * Note: Different kinds of host controller have different "scheduling
931 * horizons". While one type might support scheduling only 32 frames
932 * into the future, others could support scheduling up to 1024 frames
936 int usb_get_current_frame_number(struct usb_device *dev)
938 return usb_hcd_get_frame_number(dev);
940 EXPORT_SYMBOL_GPL(usb_get_current_frame_number);
942 /*-------------------------------------------------------------------*/
944 * __usb_get_extra_descriptor() finds a descriptor of specific type in the
945 * extra field of the interface and endpoint descriptor structs.
948 int __usb_get_extra_descriptor(char *buffer, unsigned size,
949 unsigned char type, void **ptr, size_t minsize)
951 struct usb_descriptor_header *header;
953 while (size >= sizeof(struct usb_descriptor_header)) {
954 header = (struct usb_descriptor_header *)buffer;
956 if (header->bLength < 2 || header->bLength > size) {
958 "%s: bogus descriptor, type %d length %d\n",
960 header->bDescriptorType,
965 if (header->bDescriptorType == type && header->bLength >= minsize) {
970 buffer += header->bLength;
971 size -= header->bLength;
975 EXPORT_SYMBOL_GPL(__usb_get_extra_descriptor);
978 * usb_alloc_coherent - allocate dma-consistent buffer for URB_NO_xxx_DMA_MAP
979 * @dev: device the buffer will be used with
980 * @size: requested buffer size
981 * @mem_flags: affect whether allocation may block
982 * @dma: used to return DMA address of buffer
984 * Return: Either null (indicating no buffer could be allocated), or the
985 * cpu-space pointer to a buffer that may be used to perform DMA to the
986 * specified device. Such cpu-space buffers are returned along with the DMA
987 * address (through the pointer provided).
990 * These buffers are used with URB_NO_xxx_DMA_MAP set in urb->transfer_flags
991 * to avoid behaviors like using "DMA bounce buffers", or thrashing IOMMU
992 * hardware during URB completion/resubmit. The implementation varies between
993 * platforms, depending on details of how DMA will work to this device.
994 * Using these buffers also eliminates cacheline sharing problems on
995 * architectures where CPU caches are not DMA-coherent. On systems without
996 * bus-snooping caches, these buffers are uncached.
998 * When the buffer is no longer used, free it with usb_free_coherent().
1000 void *usb_alloc_coherent(struct usb_device *dev, size_t size, gfp_t mem_flags,
1003 if (!dev || !dev->bus)
1005 return hcd_buffer_alloc(dev->bus, size, mem_flags, dma);
1007 EXPORT_SYMBOL_GPL(usb_alloc_coherent);
1010 * usb_free_coherent - free memory allocated with usb_alloc_coherent()
1011 * @dev: device the buffer was used with
1012 * @size: requested buffer size
1013 * @addr: CPU address of buffer
1014 * @dma: DMA address of buffer
1016 * This reclaims an I/O buffer, letting it be reused. The memory must have
1017 * been allocated using usb_alloc_coherent(), and the parameters must match
1018 * those provided in that allocation request.
1020 void usb_free_coherent(struct usb_device *dev, size_t size, void *addr,
1023 if (!dev || !dev->bus)
1027 hcd_buffer_free(dev->bus, size, addr, dma);
1029 EXPORT_SYMBOL_GPL(usb_free_coherent);
1032 * Notifications of device and interface registration
1034 static int usb_bus_notify(struct notifier_block *nb, unsigned long action,
1037 struct device *dev = data;
1040 case BUS_NOTIFY_ADD_DEVICE:
1041 if (dev->type == &usb_device_type)
1042 (void) usb_create_sysfs_dev_files(to_usb_device(dev));
1043 else if (dev->type == &usb_if_device_type)
1044 usb_create_sysfs_intf_files(to_usb_interface(dev));
1047 case BUS_NOTIFY_DEL_DEVICE:
1048 if (dev->type == &usb_device_type)
1049 usb_remove_sysfs_dev_files(to_usb_device(dev));
1050 else if (dev->type == &usb_if_device_type)
1051 usb_remove_sysfs_intf_files(to_usb_interface(dev));
1057 static struct notifier_block usb_bus_nb = {
1058 .notifier_call = usb_bus_notify,
1061 static struct dentry *usb_devices_root;
1063 static void usb_debugfs_init(void)
1065 usb_devices_root = debugfs_create_file("devices", 0444, usb_debug_root,
1066 NULL, &usbfs_devices_fops);
1069 static void usb_debugfs_cleanup(void)
1071 debugfs_remove(usb_devices_root);
1077 static int __init usb_init(void)
1080 if (usb_disabled()) {
1081 pr_info("%s: USB support disabled\n", usbcore_name);
1084 usb_init_pool_max();
1088 usb_acpi_register();
1089 retval = bus_register(&usb_bus_type);
1091 goto bus_register_failed;
1092 retval = bus_register_notifier(&usb_bus_type, &usb_bus_nb);
1094 goto bus_notifier_failed;
1095 retval = usb_major_init();
1097 goto major_init_failed;
1098 retval = usb_register(&usbfs_driver);
1100 goto driver_register_failed;
1101 retval = usb_devio_init();
1103 goto usb_devio_init_failed;
1104 retval = usb_hub_init();
1106 goto hub_init_failed;
1107 retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
1113 usb_devio_cleanup();
1114 usb_devio_init_failed:
1115 usb_deregister(&usbfs_driver);
1116 driver_register_failed:
1117 usb_major_cleanup();
1119 bus_unregister_notifier(&usb_bus_type, &usb_bus_nb);
1120 bus_notifier_failed:
1121 bus_unregister(&usb_bus_type);
1122 bus_register_failed:
1123 usb_acpi_unregister();
1124 usb_debugfs_cleanup();
1132 static void __exit usb_exit(void)
1134 /* This will matter if shutdown/reboot does exitcalls. */
1138 usb_release_quirk_list();
1139 usb_deregister_device_driver(&usb_generic_driver);
1140 usb_major_cleanup();
1141 usb_deregister(&usbfs_driver);
1142 usb_devio_cleanup();
1144 bus_unregister_notifier(&usb_bus_type, &usb_bus_nb);
1145 bus_unregister(&usb_bus_type);
1146 usb_acpi_unregister();
1147 usb_debugfs_cleanup();
1148 idr_destroy(&usb_bus_idr);
1151 subsys_initcall(usb_init);
1152 module_exit(usb_exit);
1153 MODULE_LICENSE("GPL");