x86/speculation/mds: Fix documentation typo

[linux/fpc-iii.git] / drivers / usb / core / usb.c

/*
 * 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.
 * SPDX-License-Identifier: GPL-2.0
 *
 * 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.
 * It should be considered a slave, 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/interrupt.h>  /* for in_interrupt() */
#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 "usb.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
static int usb_autosuspend_delay = 2;           /* Default delay value,
                                                 * in seconds */
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, void *data)
{
        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;
}


/**
 * 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: !in_interrupt()
 *
 * 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;
        /*
         * Fake a dma_mask/offset for the USB device:
         * We cannot really use the dma-mapping API (dma_alloc_* and
         * dma_map_*) for USB devices but instead need to use
         * usb_alloc_coherent and pass data in 'urb's, but some subsystems
         * manually look into the mask/offset pair to determine whether
         * they need bounce buffers.
         * Note: calling dma_set_mask() on a USB device would set the
         * mask for the entire HCD, so don't do that.
         */
        dev->dev.dma_mask = bus->sysdev->dma_mask;
        dev->dev.dma_pfn_offset = bus->sysdev->dma_pfn_offset;
        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_child_node(parent->dev.of_node,
                                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
        if (root_hub)   /* Root hub always ok [and always wired] */
                dev->authorized = 1;
        else {
                dev->authorized = !!HCD_DEV_AUTHORIZED(usb_hcd);
                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.
 *
 * 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.
 *
 * 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 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
 *      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);

/**
 * usb_buffer_map - create DMA mapping(s) for an urb
 * @urb: urb whose transfer_buffer/setup_packet will be mapped
 *
 * URB_NO_TRANSFER_DMA_MAP is added to urb->transfer_flags if the operation
 * succeeds. If the device is connected to this system through a non-DMA
 * controller, this operation always succeeds.
 *
 * This call would normally be used for an urb which is reused, perhaps
 * as the target of a large periodic transfer, with usb_buffer_dmasync()
 * calls to synchronize memory and dma state.
 *
 * Reverse the effect of this call with usb_buffer_unmap().
 *
 * Return: Either %NULL (indicating no buffer could be mapped), or @urb.
 *
 */
#if 0
struct urb *usb_buffer_map(struct urb *urb)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!urb
                        || !urb->dev
                        || !(bus = urb->dev->bus)
                        || !(controller = bus->sysdev))
                return NULL;

        if (controller->dma_mask) {
                urb->transfer_dma = dma_map_single(controller,
                        urb->transfer_buffer, urb->transfer_buffer_length,
                        usb_pipein(urb->pipe)
                                ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
        /* FIXME generic api broken like pci, can't report errors */
        /* if (urb->transfer_dma == DMA_ADDR_INVALID) return 0; */
        } else
                urb->transfer_dma = ~0;
        urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
        return urb;
}
EXPORT_SYMBOL_GPL(usb_buffer_map);
#endif  /*  0  */

/* XXX DISABLED, no users currently.  If you wish to re-enable this
 * XXX please determine whether the sync is to transfer ownership of
 * XXX the buffer from device to cpu or vice verse, and thusly use the
 * XXX appropriate _for_{cpu,device}() method.  -DaveM
 */
#if 0

/**
 * usb_buffer_dmasync - synchronize DMA and CPU view of buffer(s)
 * @urb: urb whose transfer_buffer/setup_packet will be synchronized
 */
void usb_buffer_dmasync(struct urb *urb)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!urb
                        || !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
                        || !urb->dev
                        || !(bus = urb->dev->bus)
                        || !(controller = bus->sysdev))
                return;

        if (controller->dma_mask) {
                dma_sync_single_for_cpu(controller,
                        urb->transfer_dma, urb->transfer_buffer_length,
                        usb_pipein(urb->pipe)
                                ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
                if (usb_pipecontrol(urb->pipe))
                        dma_sync_single_for_cpu(controller,
                                        urb->setup_dma,
                                        sizeof(struct usb_ctrlrequest),
                                        DMA_TO_DEVICE);
        }
}
EXPORT_SYMBOL_GPL(usb_buffer_dmasync);
#endif

/**
 * usb_buffer_unmap - free DMA mapping(s) for an urb
 * @urb: urb whose transfer_buffer will be unmapped
 *
 * Reverses the effect of usb_buffer_map().
 */
#if 0
void usb_buffer_unmap(struct urb *urb)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!urb
                        || !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
                        || !urb->dev
                        || !(bus = urb->dev->bus)
                        || !(controller = bus->sysdev))
                return;

        if (controller->dma_mask) {
                dma_unmap_single(controller,
                        urb->transfer_dma, urb->transfer_buffer_length,
                        usb_pipein(urb->pipe)
                                ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
        }
        urb->transfer_flags &= ~URB_NO_TRANSFER_DMA_MAP;
}
EXPORT_SYMBOL_GPL(usb_buffer_unmap);
#endif  /*  0  */

#if 0
/**
 * usb_buffer_map_sg - create scatterlist DMA mapping(s) for an endpoint
 * @dev: device to which the scatterlist will be mapped
 * @is_in: mapping transfer direction
 * @sg: the scatterlist to map
 * @nents: the number of entries in the scatterlist
 *
 * Return: Either < 0 (indicating no buffers could be mapped), or the
 * number of DMA mapping array entries in the scatterlist.
 *
 * Note:
 * The caller is responsible for placing the resulting DMA addresses from
 * the scatterlist into URB transfer buffer pointers, and for setting the
 * URB_NO_TRANSFER_DMA_MAP transfer flag in each of those URBs.
 *
 * Top I/O rates come from queuing URBs, instead of waiting for each one
 * to complete before starting the next I/O.   This is particularly easy
 * to do with scatterlists.  Just allocate and submit one URB for each DMA
 * mapping entry returned, stopping on the first error or when all succeed.
 * Better yet, use the usb_sg_*() calls, which do that (and more) for you.
 *
 * This call would normally be used when translating scatterlist requests,
 * rather than usb_buffer_map(), since on some hardware (with IOMMUs) it
 * may be able to coalesce mappings for improved I/O efficiency.
 *
 * Reverse the effect of this call with usb_buffer_unmap_sg().
 */
int usb_buffer_map_sg(const struct usb_device *dev, int is_in,
                      struct scatterlist *sg, int nents)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!dev
                        || !(bus = dev->bus)
                        || !(controller = bus->sysdev)
                        || !controller->dma_mask)
                return -EINVAL;

        /* FIXME generic api broken like pci, can't report errors */
        return dma_map_sg(controller, sg, nents,
                        is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE) ? : -ENOMEM;
}
EXPORT_SYMBOL_GPL(usb_buffer_map_sg);
#endif

/* XXX DISABLED, no users currently.  If you wish to re-enable this
 * XXX please determine whether the sync is to transfer ownership of
 * XXX the buffer from device to cpu or vice verse, and thusly use the
 * XXX appropriate _for_{cpu,device}() method.  -DaveM
 */
#if 0

/**
 * usb_buffer_dmasync_sg - synchronize DMA and CPU view of scatterlist buffer(s)
 * @dev: device to which the scatterlist will be mapped
 * @is_in: mapping transfer direction
 * @sg: the scatterlist to synchronize
 * @n_hw_ents: the positive return value from usb_buffer_map_sg
 *
 * Use this when you are re-using a scatterlist's data buffers for
 * another USB request.
 */
void usb_buffer_dmasync_sg(const struct usb_device *dev, int is_in,
                           struct scatterlist *sg, int n_hw_ents)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!dev
                        || !(bus = dev->bus)
                        || !(controller = bus->sysdev)
                        || !controller->dma_mask)
                return;

        dma_sync_sg_for_cpu(controller, sg, n_hw_ents,
                            is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}
EXPORT_SYMBOL_GPL(usb_buffer_dmasync_sg);
#endif

#if 0
/**
 * usb_buffer_unmap_sg - free DMA mapping(s) for a scatterlist
 * @dev: device to which the scatterlist will be mapped
 * @is_in: mapping transfer direction
 * @sg: the scatterlist to unmap
 * @n_hw_ents: the positive return value from usb_buffer_map_sg
 *
 * Reverses the effect of usb_buffer_map_sg().
 */
void usb_buffer_unmap_sg(const struct usb_device *dev, int is_in,
                         struct scatterlist *sg, int n_hw_ents)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!dev
                        || !(bus = dev->bus)
                        || !(controller = bus->sysdev)
                        || !controller->dma_mask)
                return;

        dma_unmap_sg(controller, sg, n_hw_ents,
                        is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}
EXPORT_SYMBOL_GPL(usb_buffer_unmap_sg);
#endif

/*
 * 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,
};

struct dentry *usb_debug_root;
EXPORT_SYMBOL_GPL(usb_debug_root);

static struct dentry *usb_debug_devices;

static int usb_debugfs_init(void)
{
        usb_debug_root = debugfs_create_dir("usb", NULL);
        if (!usb_debug_root)
                return -ENOENT;

        usb_debug_devices = debugfs_create_file("devices", 0444,
                                                usb_debug_root, NULL,
                                                &usbfs_devices_fops);
        if (!usb_debug_devices) {
                debugfs_remove(usb_debug_root);
                usb_debug_root = NULL;
                return -ENOENT;
        }

        return 0;
}

static void usb_debugfs_cleanup(void)
{
        debugfs_remove(usb_debug_devices);
        debugfs_remove(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();

        retval = usb_debugfs_init();
        if (retval)
                goto out;

        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_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");