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 // SPDX-License-Identifier: GPL-2.0
 /*
  * drivers/usb/core/usb.c
  *
  * (C) Copyright Linus Torvalds 1999
  * (C) Copyright Johannes Erdfelt 1999-2001
  * (C) Copyright Andreas Gal 1999
  * (C) Copyright Gregory P. Smith 1999
  * (C) Copyright Deti Fliegl 1999 (new USB architecture)
  * (C) Copyright Randy Dunlap 2000
  * (C) Copyright David Brownell 2000-2004
  * (C) Copyright Yggdrasil Computing, Inc. 2000
  *     (usb_device_id matching changes by Adam J. Richter)
  * (C) Copyright Greg Kroah-Hartman 2002-2003
  *
  * Released under the GPLv2 only.
  *
  * NOTE! This is not actually a driver at all, rather this is
  * just a collection of helper routines that implement the
  * generic USB things that the real drivers can use..
  *
  * Think of this as a "USB library" rather than anything else,
  * with no callbacks.  Callbacks are evil.
  */
 
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/string.h>
 #include <linux/bitops.h>
 #include <linux/slab.h>
 #include <linux/kmod.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/errno.h>
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 #include <linux/debugfs.h>
 #include <linux/usb/of.h>
 
 #include <asm/io.h>
 #include <linux/scatterlist.h>
 #include <linux/mm.h>
 #include <linux/dma-mapping.h>
 
 #include "hub.h"
 
 const char *usbcore_name = "usbcore";
 
 static bool nousb;  /* Disable USB when built into kernel image */
 
 module_param(nousb, bool, 0444);
 
 /*
  * for external read access to <nousb>
  */
 int usb_disabled(void)
 {
     return nousb;
 }
 EXPORT_SYMBOL_GPL(usb_disabled);
 
 #ifdef  CONFIG_PM
 /* Default delay value, in seconds */
 static int usb_autosuspend_delay = CONFIG_USB_AUTOSUSPEND_DELAY;
 module_param_named(autosuspend, usb_autosuspend_delay, int, 0644);
 MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
 
 #else
 #define usb_autosuspend_delay       0
 #endif
 
 static bool match_endpoint(struct usb_endpoint_descriptor *epd,
         struct usb_endpoint_descriptor **bulk_in,
         struct usb_endpoint_descriptor **bulk_out,
         struct usb_endpoint_descriptor **int_in,
         struct usb_endpoint_descriptor **int_out)
 {
     switch (usb_endpoint_type(epd)) {
     case USB_ENDPOINT_XFER_BULK:
         if (usb_endpoint_dir_in(epd)) {
             if (bulk_in && !*bulk_in) {
                 *bulk_in = epd;
                 break;
             }
         } else {
             if (bulk_out && !*bulk_out) {
                 *bulk_out = epd;
                 break;
             }
         }
 
         return false;
     case USB_ENDPOINT_XFER_INT:
         if (usb_endpoint_dir_in(epd)) {
             if (int_in && !*int_in) {
                 *int_in = epd;
                 break;
             }
         } else {
             if (int_out && !*int_out) {
                 *int_out = epd;
                 break;
             }
         }
 
         return false;
     default:
         return false;
     }
 
     return (!bulk_in || *bulk_in) && (!bulk_out || *bulk_out) &&
             (!int_in || *int_in) && (!int_out || *int_out);
 }
 
 /**
  * usb_find_common_endpoints() -- look up common endpoint descriptors
  * @alt:    alternate setting to search
  * @bulk_in:    pointer to descriptor pointer, or NULL
  * @bulk_out:   pointer to descriptor pointer, or NULL
  * @int_in: pointer to descriptor pointer, or NULL
  * @int_out:    pointer to descriptor pointer, or NULL
  *
  * Search the alternate setting's endpoint descriptors for the first bulk-in,
  * bulk-out, interrupt-in and interrupt-out endpoints and return them in the
  * provided pointers (unless they are NULL).
  *
  * If a requested endpoint is not found, the corresponding pointer is set to
  * NULL.
  *
  * Return: Zero if all requested descriptors were found, or -ENXIO otherwise.
  */
 int usb_find_common_endpoints(struct usb_host_interface *alt,
         struct usb_endpoint_descriptor **bulk_in,
         struct usb_endpoint_descriptor **bulk_out,
         struct usb_endpoint_descriptor **int_in,
         struct usb_endpoint_descriptor **int_out)
 {
     struct usb_endpoint_descriptor *epd;
     int i;
 
     if (bulk_in)
         *bulk_in = NULL;
     if (bulk_out)
         *bulk_out = NULL;
     if (int_in)
         *int_in = NULL;
     if (int_out)
         *int_out = NULL;
 
     for (i = 0; i < alt->desc.bNumEndpoints; ++i) {
         epd = &alt->endpoint[i].desc;
 
         if (match_endpoint(epd, bulk_in, bulk_out, int_in, int_out))
             return 0;
     }
 
     return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(usb_find_common_endpoints);
 
 /**
  * usb_find_common_endpoints_reverse() -- look up common endpoint descriptors
  * @alt:    alternate setting to search
  * @bulk_in:    pointer to descriptor pointer, or NULL
  * @bulk_out:   pointer to descriptor pointer, or NULL
  * @int_in: pointer to descriptor pointer, or NULL
  * @int_out:    pointer to descriptor pointer, or NULL
  *
  * Search the alternate setting's endpoint descriptors for the last bulk-in,
  * bulk-out, interrupt-in and interrupt-out endpoints and return them in the
  * provided pointers (unless they are NULL).
  *
  * If a requested endpoint is not found, the corresponding pointer is set to
  * NULL.
  *
  * Return: Zero if all requested descriptors were found, or -ENXIO otherwise.
  */
 int usb_find_common_endpoints_reverse(struct usb_host_interface *alt,
         struct usb_endpoint_descriptor **bulk_in,
         struct usb_endpoint_descriptor **bulk_out,
         struct usb_endpoint_descriptor **int_in,
         struct usb_endpoint_descriptor **int_out)
 {
     struct usb_endpoint_descriptor *epd;
     int i;
 
     if (bulk_in)
         *bulk_in = NULL;
     if (bulk_out)
         *bulk_out = NULL;
     if (int_in)
         *int_in = NULL;
     if (int_out)
         *int_out = NULL;
 
     for (i = alt->desc.bNumEndpoints - 1; i >= 0; --i) {
         epd = &alt->endpoint[i].desc;
 
         if (match_endpoint(epd, bulk_in, bulk_out, int_in, int_out))
             return 0;
     }
 
     return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(usb_find_common_endpoints_reverse);
 
 /**
  * usb_find_alt_setting() - Given a configuration, find the alternate setting
  * for the given interface.
  * @config: the configuration to search (not necessarily the current config).
  * @iface_num: interface number to search in
  * @alt_num: alternate interface setting number to search for.
  *
  * Search the configuration's interface cache for the given alt setting.
  *
  * Return: The alternate setting, if found. %NULL otherwise.
  */
 struct usb_host_interface *usb_find_alt_setting(
         struct usb_host_config *config,
         unsigned int iface_num,
         unsigned int alt_num)
 {
     struct usb_interface_cache *intf_cache = NULL;
     int i;
 
     if (!config)
         return NULL;
     for (i = 0; i < config->desc.bNumInterfaces; i++) {
         if (config->intf_cache[i]->altsetting[0].desc.bInterfaceNumber
                 == iface_num) {
             intf_cache = config->intf_cache[i];
             break;
         }
     }
     if (!intf_cache)
         return NULL;
     for (i = 0; i < intf_cache->num_altsetting; i++)
         if (intf_cache->altsetting[i].desc.bAlternateSetting == alt_num)
             return &intf_cache->altsetting[i];
 
     printk(KERN_DEBUG "Did not find alt setting %u for intf %u, "
             "config %u\n", alt_num, iface_num,
             config->desc.bConfigurationValue);
     return NULL;
 }
 EXPORT_SYMBOL_GPL(usb_find_alt_setting);
 
 /**
  * usb_ifnum_to_if - get the interface object with a given interface number
  * @dev: the device whose current configuration is considered
  * @ifnum: the desired interface
  *
  * This walks the device descriptor for the currently active configuration
  * to find the interface object with the particular interface number.
  *
  * Note that configuration descriptors are not required to assign interface
  * numbers sequentially, so that it would be incorrect to assume that
  * the first interface in that descriptor corresponds to interface zero.
  * This routine helps device drivers avoid such mistakes.
  * However, you should make sure that you do the right thing with any
  * alternate settings available for this interfaces.
  *
  * Don't call this function unless you are bound to one of the interfaces
  * on this device or you have locked the device!
  *
  * Return: A pointer to the interface that has @ifnum as interface number,
  * if found. %NULL otherwise.
  */
 struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev,
                       unsigned ifnum)
 {
     struct usb_host_config *config = dev->actconfig;
     int i;
 
     if (!config)
         return NULL;
     for (i = 0; i < config->desc.bNumInterfaces; i++)
         if (config->interface[i]->altsetting[0]
                 .desc.bInterfaceNumber == ifnum)
             return config->interface[i];
 
     return NULL;
 }
 EXPORT_SYMBOL_GPL(usb_ifnum_to_if);
 
 /**
  * usb_altnum_to_altsetting - get the altsetting structure with a given alternate setting number.
  * @intf: the interface containing the altsetting in question
  * @altnum: the desired alternate setting number
  *
  * This searches the altsetting array of the specified interface for
  * an entry with the correct bAlternateSetting value.
  *
  * Note that altsettings need not be stored sequentially by number, so
  * it would be incorrect to assume that the first altsetting entry in
  * the array corresponds to altsetting zero.  This routine helps device
  * drivers avoid such mistakes.
  *
  * Don't call this function unless you are bound to the intf interface
  * or you have locked the device!
  *
  * Return: A pointer to the entry of the altsetting array of @intf that
  * has @altnum as the alternate setting number. %NULL if not found.
  */
 struct usb_host_interface *usb_altnum_to_altsetting(
                     const struct usb_interface *intf,
                     unsigned int altnum)
 {
     int i;
 
     for (i = 0; i < intf->num_altsetting; i++) {
         if (intf->altsetting[i].desc.bAlternateSetting == altnum)
             return &intf->altsetting[i];
     }
     return NULL;
 }
 EXPORT_SYMBOL_GPL(usb_altnum_to_altsetting);
 
 struct find_interface_arg {
     int minor;
     struct device_driver *drv;
 };
 
 static int __find_interface(struct device *dev, const void *data)
 {
     const struct find_interface_arg *arg = data;
     struct usb_interface *intf;
 
     if (!is_usb_interface(dev))
         return 0;
 
     if (dev->driver != arg->drv)
         return 0;
     intf = to_usb_interface(dev);
     return intf->minor == arg->minor;
 }
 
 /**
  * usb_find_interface - find usb_interface pointer for driver and device
  * @drv: the driver whose current configuration is considered
  * @minor: the minor number of the desired device
  *
  * This walks the bus device list and returns a pointer to the interface
  * with the matching minor and driver.  Note, this only works for devices
  * that share the USB major number.
  *
  * Return: A pointer to the interface with the matching major and @minor.
  */
 struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
 {
     struct find_interface_arg argb;
     struct device *dev;
 
     argb.minor = minor;
     argb.drv = &drv->drvwrap.driver;
 
     dev = bus_find_device(&usb_bus_type, NULL, &argb, __find_interface);
 
     /* Drop reference count from bus_find_device */
     put_device(dev);
 
     return dev ? to_usb_interface(dev) : NULL;
 }
 EXPORT_SYMBOL_GPL(usb_find_interface);
 
 struct each_dev_arg {
     void *data;
     int (*fn)(struct usb_device *, void *);
 };
 
 static int __each_dev(struct device *dev, void *data)
 {
     struct each_dev_arg *arg = (struct each_dev_arg *)data;
 
     /* There are struct usb_interface on the same bus, filter them out */
     if (!is_usb_device(dev))
         return 0;
 
     return arg->fn(to_usb_device(dev), arg->data);
 }
 
 /**
  * usb_for_each_dev - iterate over all USB devices in the system
  * @data: data pointer that will be handed to the callback function
  * @fn: callback function to be called for each USB device
  *
  * Iterate over all USB devices and call @fn for each, passing it @data. If it
  * returns anything other than 0, we break the iteration prematurely and return
  * that value.
  */
 int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
 {
     struct each_dev_arg arg = {data, fn};
 
     return bus_for_each_dev(&usb_bus_type, NULL, &arg, __each_dev);
 }
 EXPORT_SYMBOL_GPL(usb_for_each_dev);
 
 /**
  * usb_release_dev - free a usb device structure when all users of it are finished.
  * @dev: device that's been disconnected
  *
  * Will be called only by the device core when all users of this usb device are
  * done.
  */
 static void usb_release_dev(struct device *dev)
 {
     struct usb_device *udev;
     struct usb_hcd *hcd;
 
     udev = to_usb_device(dev);
     hcd = bus_to_hcd(udev->bus);
 
     usb_destroy_configuration(udev);
     usb_release_bos_descriptor(udev);
     of_node_put(dev->of_node);
     usb_put_hcd(hcd);
     kfree(udev->product);
     kfree(udev->manufacturer);
     kfree(udev->serial);
     kfree(udev);
 }
 
 static int usb_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
     struct usb_device *usb_dev;
 
     usb_dev = to_usb_device(dev);
 
     if (add_uevent_var(env, "BUSNUM=%03d", usb_dev->bus->busnum))
         return -ENOMEM;
 
     if (add_uevent_var(env, "DEVNUM=%03d", usb_dev->devnum))
         return -ENOMEM;
 
     return 0;
 }
 
 #ifdef  CONFIG_PM
 
 /* USB device Power-Management thunks.
  * There's no need to distinguish here between quiescing a USB device
  * and powering it down; the generic_suspend() routine takes care of
  * it by skipping the usb_port_suspend() call for a quiesce.  And for
  * USB interfaces there's no difference at all.
  */
 
 static int usb_dev_prepare(struct device *dev)
 {
     return 0;       /* Implement eventually? */
 }
 
 static void usb_dev_complete(struct device *dev)
 {
     /* Currently used only for rebinding interfaces */
     usb_resume_complete(dev);
 }
 
 static int usb_dev_suspend(struct device *dev)
 {
     return usb_suspend(dev, PMSG_SUSPEND);
 }
 
 static int usb_dev_resume(struct device *dev)
 {
     return usb_resume(dev, PMSG_RESUME);
 }
 
 static int usb_dev_freeze(struct device *dev)
 {
     return usb_suspend(dev, PMSG_FREEZE);
 }
 
 static int usb_dev_thaw(struct device *dev)
 {
     return usb_resume(dev, PMSG_THAW);
 }
 
 static int usb_dev_poweroff(struct device *dev)
 {
     return usb_suspend(dev, PMSG_HIBERNATE);
 }
 
 static int usb_dev_restore(struct device *dev)
 {
     return usb_resume(dev, PMSG_RESTORE);
 }
 
 static const struct dev_pm_ops usb_device_pm_ops = {
     .prepare =  usb_dev_prepare,
     .complete = usb_dev_complete,
     .suspend =  usb_dev_suspend,
     .resume =   usb_dev_resume,
     .freeze =   usb_dev_freeze,
     .thaw =     usb_dev_thaw,
     .poweroff = usb_dev_poweroff,
     .restore =  usb_dev_restore,
     .runtime_suspend =  usb_runtime_suspend,
     .runtime_resume =   usb_runtime_resume,
     .runtime_idle =     usb_runtime_idle,
 };
 
 #endif  /* CONFIG_PM */
 
 
 static char *usb_devnode(struct device *dev,
              umode_t *mode, kuid_t *uid, kgid_t *gid)
 {
     struct usb_device *usb_dev;
 
     usb_dev = to_usb_device(dev);
     return kasprintf(GFP_KERNEL, "bus/usb/%03d/%03d",
              usb_dev->bus->busnum, usb_dev->devnum);
 }
 
 struct device_type usb_device_type = {
     .name =     "usb_device",
     .release =  usb_release_dev,
     .uevent =   usb_dev_uevent,
     .devnode =  usb_devnode,
 #ifdef CONFIG_PM
     .pm =       &usb_device_pm_ops,
 #endif
 };
 
 
 /* Returns 1 if @usb_bus is WUSB, 0 otherwise */
 static unsigned usb_bus_is_wusb(struct usb_bus *bus)
 {
     struct usb_hcd *hcd = bus_to_hcd(bus);
     return hcd->wireless;
 }
 
 static bool usb_dev_authorized(struct usb_device *dev, struct usb_hcd *hcd)
 {
     struct usb_hub *hub;
 
     if (!dev->parent)
         return true; /* Root hub always ok [and always wired] */
 
     switch (hcd->dev_policy) {
     case USB_DEVICE_AUTHORIZE_NONE:
     default:
         return false;
 
     case USB_DEVICE_AUTHORIZE_ALL:
         return true;
 
     case USB_DEVICE_AUTHORIZE_INTERNAL:
         hub = usb_hub_to_struct_hub(dev->parent);
         return hub->ports[dev->portnum - 1]->connect_type ==
                 USB_PORT_CONNECT_TYPE_HARD_WIRED;
     }
 }
 
 /**
  * usb_alloc_dev - usb device constructor (usbcore-internal)
  * @parent: hub to which device is connected; null to allocate a root hub
  * @bus: bus used to access the device
  * @port1: one-based index of port; ignored for root hubs
  *
  * Context: task context, might sleep.
  *
  * Only hub drivers (including virtual root hub drivers for host
  * controllers) should ever call this.
  *
  * This call may not be used in a non-sleeping context.
  *
  * Return: On success, a pointer to the allocated usb device. %NULL on
  * failure.
  */
 struct usb_device *usb_alloc_dev(struct usb_device *parent,
                  struct usb_bus *bus, unsigned port1)
 {
     struct usb_device *dev;
     struct usb_hcd *usb_hcd = bus_to_hcd(bus);
     unsigned root_hub = 0;
     unsigned raw_port = port1;
 
     dev = kzalloc(sizeof(*dev), GFP_KERNEL);
     if (!dev)
         return NULL;
 
     if (!usb_get_hcd(usb_hcd)) {
         kfree(dev);
         return NULL;
     }
     /* Root hubs aren't true devices, so don't allocate HCD resources */
     if (usb_hcd->driver->alloc_dev && parent &&
         !usb_hcd->driver->alloc_dev(usb_hcd, dev)) {
         usb_put_hcd(bus_to_hcd(bus));
         kfree(dev);
         return NULL;
     }
 
     device_initialize(&dev->dev);
     dev->dev.bus = &usb_bus_type;
     dev->dev.type = &usb_device_type;
     dev->dev.groups = usb_device_groups;
     set_dev_node(&dev->dev, dev_to_node(bus->sysdev));
     dev->state = USB_STATE_ATTACHED;
     dev->lpm_disable_count = 1;
     atomic_set(&dev->urbnum, 0);
 
     INIT_LIST_HEAD(&dev->ep0.urb_list);
     dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
     dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
     /* ep0 maxpacket comes later, from device descriptor */
     usb_enable_endpoint(dev, &dev->ep0, false);
     dev->can_submit = 1;
 
     /* Save readable and stable topology id, distinguishing devices
      * by location for diagnostics, tools, driver model, etc.  The
      * string is a path along hub ports, from the root.  Each device's
      * dev->devpath will be stable until USB is re-cabled, and hubs
      * are often labeled with these port numbers.  The name isn't
      * as stable:  bus->busnum changes easily from modprobe order,
      * cardbus or pci hotplugging, and so on.
      */
     if (unlikely(!parent)) {
         dev->devpath[0] = '0';
         dev->route = 0;
 
         dev->dev.parent = bus->controller;
         device_set_of_node_from_dev(&dev->dev, bus->sysdev);
         dev_set_name(&dev->dev, "usb%d", bus->busnum);
         root_hub = 1;
     } else {
         /* match any labeling on the hubs; it's one-based */
         if (parent->devpath[0] == '0') {
             snprintf(dev->devpath, sizeof dev->devpath,
                 "%d", port1);
             /* Root ports are not counted in route string */
             dev->route = 0;
         } else {
             snprintf(dev->devpath, sizeof dev->devpath,
                 "%s.%d", parent->devpath, port1);
             /* Route string assumes hubs have less than 16 ports */
             if (port1 < 15)
                 dev->route = parent->route +
                     (port1 << ((parent->level - 1)*4));
             else
                 dev->route = parent->route +
                     (15 << ((parent->level - 1)*4));
         }
 
         dev->dev.parent = &parent->dev;
         dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);
 
         if (!parent->parent) {
             /* device under root hub's port */
             raw_port = usb_hcd_find_raw_port_number(usb_hcd,
                 port1);
         }
         dev->dev.of_node = usb_of_get_device_node(parent, raw_port);
 
         /* hub driver sets up TT records */
     }
 
     dev->portnum = port1;
     dev->bus = bus;
     dev->parent = parent;
     INIT_LIST_HEAD(&dev->filelist);
 
 #ifdef  CONFIG_PM
     pm_runtime_set_autosuspend_delay(&dev->dev,
             usb_autosuspend_delay * 1000);
     dev->connect_time = jiffies;
     dev->active_duration = -jiffies;
 #endif
 
     dev->authorized = usb_dev_authorized(dev, usb_hcd);
     if (!root_hub)
         dev->wusb = usb_bus_is_wusb(bus) ? 1 : 0;
 
     return dev;
 }
 EXPORT_SYMBOL_GPL(usb_alloc_dev);
 
 /**
  * usb_get_dev - increments the reference count of the usb device structure
  * @dev: the device being referenced
  *
  * Each live reference to a device should be refcounted.
  *
  * Drivers for USB interfaces should normally record such references in
  * their probe() methods, when they bind to an interface, and release
  * them by calling usb_put_dev(), in their disconnect() methods.
  * However, if a driver does not access the usb_device structure after
  * its disconnect() method returns then refcounting is not necessary,
  * because the USB core guarantees that a usb_device will not be
  * deallocated until after all of its interface drivers have been unbound.
  *
  * Return: A pointer to the device with the incremented reference counter.
  */
 struct usb_device *usb_get_dev(struct usb_device *dev)
 {
     if (dev)
         get_device(&dev->dev);
     return dev;
 }
 EXPORT_SYMBOL_GPL(usb_get_dev);
 
 /**
  * usb_put_dev - release a use of the usb device structure
  * @dev: device that's been disconnected
  *
  * Must be called when a user of a device is finished with it.  When the last
  * user of the device calls this function, the memory of the device is freed.
  */
 void usb_put_dev(struct usb_device *dev)
 {
     if (dev)
         put_device(&dev->dev);
 }
 EXPORT_SYMBOL_GPL(usb_put_dev);
 
 /**
  * usb_get_intf - increments the reference count of the usb interface structure
  * @intf: the interface being referenced
  *
  * Each live reference to a interface must be refcounted.
  *
  * Drivers for USB interfaces should normally record such references in
  * their probe() methods, when they bind to an interface, and release
  * them by calling usb_put_intf(), in their disconnect() methods.
  * However, if a driver does not access the usb_interface structure after
  * its disconnect() method returns then refcounting is not necessary,
  * because the USB core guarantees that a usb_interface will not be
  * deallocated until after its driver has been unbound.
  *
  * Return: A pointer to the interface with the incremented reference counter.
  */
 struct usb_interface *usb_get_intf(struct usb_interface *intf)
 {
     if (intf)
         get_device(&intf->dev);
     return intf;
 }
 EXPORT_SYMBOL_GPL(usb_get_intf);
 
 /**
  * usb_put_intf - release a use of the usb interface structure
  * @intf: interface that's been decremented
  *
  * Must be called when a user of an interface is finished with it.  When the
  * last user of the interface calls this function, the memory of the interface
  * is freed.
  */
 void usb_put_intf(struct usb_interface *intf)
 {
     if (intf)
         put_device(&intf->dev);
 }
 EXPORT_SYMBOL_GPL(usb_put_intf);
 
 /**
  * usb_intf_get_dma_device - acquire a reference on the usb interface's DMA endpoint
  * @intf: the usb interface
  *
  * While a USB device cannot perform DMA operations by itself, many USB
  * controllers can. A call to usb_intf_get_dma_device() returns the DMA endpoint
  * for the given USB interface, if any. The returned device structure must be
  * released with put_device().
  *
  * See also usb_get_dma_device().
  *
  * Returns: A reference to the usb interface's DMA endpoint; or NULL if none
  *          exists.
  */
 struct device *usb_intf_get_dma_device(struct usb_interface *intf)
 {
     struct usb_device *udev = interface_to_usbdev(intf);
     struct device *dmadev;
 
     if (!udev->bus)
         return NULL;
 
     dmadev = get_device(udev->bus->sysdev);
     if (!dmadev || !dmadev->dma_mask) {
         put_device(dmadev);
         return NULL;
     }
 
     return dmadev;
 }
 EXPORT_SYMBOL_GPL(usb_intf_get_dma_device);
 
 /*          USB device locking
  *
  * USB devices and interfaces are locked using the semaphore in their
  * embedded struct device.  The hub driver guarantees that whenever a
  * device is connected or disconnected, drivers are called with the
  * USB device locked as well as their particular interface.
  *
  * Complications arise when several devices are to be locked at the same
  * time.  Only hub-aware drivers that are part of usbcore ever have to
  * do this; nobody else needs to worry about it.  The rule for locking
  * is simple:
  *
  *  When locking both a device and its parent, always lock the
  *  parent first.
  */
 
 /**
  * usb_lock_device_for_reset - cautiously acquire the lock for a usb device structure
  * @udev: device that's being locked
  * @iface: interface bound to the driver making the request (optional)
  *
  * Attempts to acquire the device lock, but fails if the device is
  * NOTATTACHED or SUSPENDED, or if iface is specified and the interface
  * is neither BINDING nor BOUND.  Rather than sleeping to wait for the
  * lock, the routine polls repeatedly.  This is to prevent deadlock with
  * disconnect; in some drivers (such as usb-storage) the disconnect()
  * or suspend() method will block waiting for a device reset to complete.
  *
  * Return: A negative error code for failure, otherwise 0.
  */
 int usb_lock_device_for_reset(struct usb_device *udev,
                   const struct usb_interface *iface)
 {
     unsigned long jiffies_expire = jiffies + HZ;
 
     if (udev->state == USB_STATE_NOTATTACHED)
         return -ENODEV;
     if (udev->state == USB_STATE_SUSPENDED)
         return -EHOSTUNREACH;
     if (iface && (iface->condition == USB_INTERFACE_UNBINDING ||
             iface->condition == USB_INTERFACE_UNBOUND))
         return -EINTR;
 
     while (!usb_trylock_device(udev)) {
 
         /* If we can't acquire the lock after waiting one second,
          * we're probably deadlocked */
         if (time_after(jiffies, jiffies_expire))
             return -EBUSY;
 
         msleep(15);
         if (udev->state == USB_STATE_NOTATTACHED)
             return -ENODEV;
         if (udev->state == USB_STATE_SUSPENDED)
             return -EHOSTUNREACH;
         if (iface && (iface->condition == USB_INTERFACE_UNBINDING ||
                 iface->condition == USB_INTERFACE_UNBOUND))
             return -EINTR;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(usb_lock_device_for_reset);
 
 /**
  * usb_get_current_frame_number - return current bus frame number
  * @dev: the device whose bus is being queried
  *
  * Return: The current frame number for the USB host controller used
  * with the given USB device. This can be used when scheduling
  * isochronous requests.
  *
  * Note: Different kinds of host controller have different "scheduling
  * horizons". While one type might support scheduling only 32 frames
  * into the future, others could support scheduling up to 1024 frames
  * into the future.
  *
  */
 int usb_get_current_frame_number(struct usb_device *dev)
 {
     return usb_hcd_get_frame_number(dev);
 }
 EXPORT_SYMBOL_GPL(usb_get_current_frame_number);
 
 /*-------------------------------------------------------------------*/
 /*
  * __usb_get_extra_descriptor() finds a descriptor of specific type in the
  * extra field of the interface and endpoint descriptor structs.
  */
 
 int __usb_get_extra_descriptor(char *buffer, unsigned size,
                    unsigned char type, void **ptr, size_t minsize)
 {
     struct usb_descriptor_header *header;
 
     while (size >= sizeof(struct usb_descriptor_header)) {
         header = (struct usb_descriptor_header *)buffer;
 
         if (header->bLength < 2 || header->bLength > size) {
             printk(KERN_ERR
                 "%s: bogus descriptor, type %d length %d\n",
                 usbcore_name,
                 header->bDescriptorType,
                 header->bLength);
             return -1;
         }
 
         if (header->bDescriptorType == type && header->bLength >= minsize) {
             *ptr = header;
             return 0;
         }
 
         buffer += header->bLength;
         size -= header->bLength;
     }
     return -1;
 }
 EXPORT_SYMBOL_GPL(__usb_get_extra_descriptor);
 
 /**
  * usb_alloc_coherent - allocate dma-consistent buffer for URB_NO_xxx_DMA_MAP
  * @dev: device the buffer will be used with
  * @size: requested buffer size
  * @mem_flags: affect whether allocation may block
  * @dma: used to return DMA address of buffer
  *
  * Return: Either null (indicating no buffer could be allocated), or the
  * cpu-space pointer to a buffer that may be used to perform DMA to the
  * specified device.  Such cpu-space buffers are returned along with the DMA
  * address (through the pointer provided).
  *
  * Note:
  * These buffers are used with URB_NO_xxx_DMA_MAP set in urb->transfer_flags
  * to avoid behaviors like using "DMA bounce buffers", or thrashing IOMMU
  * hardware during URB completion/resubmit.  The implementation varies between
  * platforms, depending on details of how DMA will work to this device.
  * Using these buffers also eliminates cacheline sharing problems on
  * architectures where CPU caches are not DMA-coherent.  On systems without
  * bus-snooping caches, these buffers are uncached.
  *
  * When the buffer is no longer used, free it with usb_free_coherent().
  */
 void *usb_alloc_coherent(struct usb_device *dev, size_t size, gfp_t mem_flags,
              dma_addr_t *dma)
 {
     if (!dev || !dev->bus)
         return NULL;
     return hcd_buffer_alloc(dev->bus, size, mem_flags, dma);
 }
 EXPORT_SYMBOL_GPL(usb_alloc_coherent);
 
 /**
  * usb_free_coherent - free memory allocated with usb_alloc_coherent()
  * @dev: device the buffer was used with
  * @size: requested buffer size
  * @addr: CPU address of buffer
  * @dma: DMA address of buffer
  *
  * This reclaims an I/O buffer, letting it be reused.  The memory must have
  * been allocated using usb_alloc_coherent(), and the parameters must match
  * those provided in that allocation request.
  */
 void usb_free_coherent(struct usb_device *dev, size_t size, void *addr,
                dma_addr_t dma)
 {
     if (!dev || !dev->bus)
         return;
     if (!addr)
         return;
     hcd_buffer_free(dev->bus, size, addr, dma);
 }
 EXPORT_SYMBOL_GPL(usb_free_coherent);
 
 /*
  * Notifications of device and interface registration
  */
 static int usb_bus_notify(struct notifier_block *nb, unsigned long action,
         void *data)
 {
     struct device *dev = data;
 
     switch (action) {
     case BUS_NOTIFY_ADD_DEVICE:
         if (dev->type == &usb_device_type)
             (void) usb_create_sysfs_dev_files(to_usb_device(dev));
         else if (dev->type == &usb_if_device_type)
             usb_create_sysfs_intf_files(to_usb_interface(dev));
         break;
 
     case BUS_NOTIFY_DEL_DEVICE:
         if (dev->type == &usb_device_type)
             usb_remove_sysfs_dev_files(to_usb_device(dev));
         else if (dev->type == &usb_if_device_type)
             usb_remove_sysfs_intf_files(to_usb_interface(dev));
         break;
     }
     return 0;
 }
 
 static struct notifier_block usb_bus_nb = {
     .notifier_call = usb_bus_notify,
 };
 
 static void usb_debugfs_init(void)
 {
     debugfs_create_file("devices", 0444, usb_debug_root, NULL,
                 &usbfs_devices_fops);
 }
 
 static void usb_debugfs_cleanup(void)
 {
     debugfs_remove(debugfs_lookup("devices", usb_debug_root));
 }
 
 /*
  * Init
  */
 static int __init usb_init(void)
 {
     int retval;
     if (usb_disabled()) {
         pr_info("%s: USB support disabled\n", usbcore_name);
         return 0;
     }
     usb_init_pool_max();
 
     usb_debugfs_init();
 
     usb_acpi_register();
     retval = bus_register(&usb_bus_type);
     if (retval)
         goto bus_register_failed;
     retval = bus_register_notifier(&usb_bus_type, &usb_bus_nb);
     if (retval)
         goto bus_notifier_failed;
     retval = usb_major_init();
     if (retval)
         goto major_init_failed;
     retval = usb_register(&usbfs_driver);
     if (retval)
         goto driver_register_failed;
     retval = usb_devio_init();
     if (retval)
         goto usb_devio_init_failed;
     retval = usb_hub_init();
     if (retval)
         goto hub_init_failed;
     retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
     if (!retval)
         goto out;
 
     usb_hub_cleanup();
 hub_init_failed:
     usb_devio_cleanup();
 usb_devio_init_failed:
     usb_deregister(&usbfs_driver);
 driver_register_failed:
     usb_major_cleanup();
 major_init_failed:
     bus_unregister_notifier(&usb_bus_type, &usb_bus_nb);
 bus_notifier_failed:
     bus_unregister(&usb_bus_type);
 bus_register_failed:
     usb_acpi_unregister();
     usb_debugfs_cleanup();
 out:
     return retval;
 }
 
 /*
  * Cleanup
  */
 static void __exit usb_exit(void)
 {
     /* This will matter if shutdown/reboot does exitcalls. */
     if (usb_disabled())
         return;
 
     usb_release_quirk_list();
     usb_deregister_device_driver(&usb_generic_driver);
     usb_major_cleanup();
     usb_deregister(&usbfs_driver);
     usb_devio_cleanup();
     usb_hub_cleanup();
     bus_unregister_notifier(&usb_bus_type, &usb_bus_nb);
     bus_unregister(&usb_bus_type);
     usb_acpi_unregister();
     usb_debugfs_cleanup();
     idr_destroy(&usb_bus_idr);
 }
 
 subsys_initcall(usb_init);
 module_exit(usb_exit);
 MODULE_LICENSE("GPL");

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