VServer 1.9.2 (patch-2.6.8.1-vs1.9.2.diff)

[linux-2.6.git] / drivers / usb / core / usb.c

/*
 * drivers/usb/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
 *
 * 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/config.h>

#ifdef CONFIG_USB_DEBUG
        #define DEBUG
#else
        #undef DEBUG
#endif

#include <linux/module.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/smp_lock.h>
#include <linux/usb.h>

#include <asm/io.h>
#include <asm/scatterlist.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>

#include "hcd.h"
#include "usb.h"

extern int  usb_hub_init(void);
extern void usb_hub_cleanup(void);
extern int usb_major_init(void);
extern void usb_major_cleanup(void);
extern int usb_host_init(void);
extern void usb_host_cleanup(void);


const char *usbcore_name = "usbcore";

int nousb;              /* Disable USB when built into kernel image */
                        /* Not honored on modular build */


static int generic_probe (struct device *dev)
{
        return 0;
}
static int generic_remove (struct device *dev)
{
        return 0;
}

static struct device_driver usb_generic_driver = {
        .name = "usb",
        .bus = &usb_bus_type,
        .probe = generic_probe,
        .remove = generic_remove,
};

static int usb_generic_driver_data;

/* called from driver core with usb_bus_type.subsys writelock */
int usb_probe_interface(struct device *dev)
{
        struct usb_interface * intf = to_usb_interface(dev);
        struct usb_driver * driver = to_usb_driver(dev->driver);
        const struct usb_device_id *id;
        int error = -ENODEV;

        dev_dbg(dev, "%s\n", __FUNCTION__);

        if (!driver->probe)
                return error;

        id = usb_match_id (intf, driver->id_table);
        if (id) {
                dev_dbg (dev, "%s - got id\n", __FUNCTION__);
                error = driver->probe (intf, id);
        }

        return error;
}

/* called from driver core with usb_bus_type.subsys writelock */
int usb_unbind_interface(struct device *dev)
{
        struct usb_interface *intf = to_usb_interface(dev);
        struct usb_driver *driver = to_usb_driver(intf->dev.driver);

        /* release all urbs for this interface */
        usb_disable_interface(interface_to_usbdev(intf), intf);

        if (driver && driver->disconnect)
                driver->disconnect(intf);

        /* reset other interface state */
        usb_set_interface(interface_to_usbdev(intf),
                        intf->altsetting[0].desc.bInterfaceNumber,
                        0);
        usb_set_intfdata(intf, NULL);

        return 0;
}

/**
 * usb_register - register a USB driver
 * @new_driver: USB operations for the driver
 *
 * Registers a USB driver with the USB core.  The list of unattached
 * interfaces will be rescanned whenever a new driver is added, allowing
 * the new driver to attach to any recognized devices.
 * Returns a negative error code on failure and 0 on success.
 * 
 * NOTE: if you want your driver to use the USB major number, you must call
 * usb_register_dev() to enable that functionality.  This function no longer
 * takes care of that.
 */
int usb_register(struct usb_driver *new_driver)
{
        int retval = 0;

        if (nousb)
                return -ENODEV;

        new_driver->driver.name = (char *)new_driver->name;
        new_driver->driver.bus = &usb_bus_type;
        new_driver->driver.probe = usb_probe_interface;
        new_driver->driver.remove = usb_unbind_interface;

        retval = driver_register(&new_driver->driver);

        if (!retval) {
                pr_info("%s: registered new driver %s\n",
                        usbcore_name, new_driver->name);
                usbfs_update_special();
        } else {
                printk(KERN_ERR "%s: error %d registering driver %s\n",
                        usbcore_name, retval, new_driver->name);
        }

        return retval;
}

/**
 * usb_deregister - unregister a USB driver
 * @driver: USB operations of the driver to unregister
 * Context: must be able to sleep
 *
 * Unlinks the specified driver from the internal USB driver list.
 * 
 * NOTE: If you called usb_register_dev(), you still need to call
 * usb_deregister_dev() to clean up your driver's allocated minor numbers,
 * this * call will no longer do it for you.
 */
void usb_deregister(struct usb_driver *driver)
{
        pr_info("%s: deregistering driver %s\n", usbcore_name, driver->name);

        driver_unregister (&driver->driver);

        usbfs_update_special();
}

/**
 * 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
 * and returns a pointer to the interface with that particular interface
 * number, or null.
 *
 * 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 own the dev->serialize semaphore!
 */
struct usb_interface *usb_ifnum_to_if(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;
}

/**
 * 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 and returns a pointer
 * to that entry, or null.
 *
 * 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 own the device's ->serialize semaphore!
 */
struct usb_host_interface *usb_altnum_to_altsetting(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;
}

/**
 * usb_epnum_to_ep_desc - get the endpoint object with a given endpoint number
 * @dev: the device whose current configuration+altsettings is considered
 * @epnum: the desired endpoint, masked with USB_DIR_IN as appropriate.
 *
 * This walks the device descriptor for the currently active configuration,
 * and returns a pointer to the endpoint with that particular endpoint
 * number, or null.
 *
 * Note that interface descriptors are not required to list endpoint
 * numbers in any standardized order, so that it would be wrong to
 * assume that ep2in precedes either ep5in, ep2out, or even ep1out.
 * This routine helps device drivers avoid such mistakes.
 */
struct usb_endpoint_descriptor *
usb_epnum_to_ep_desc(struct usb_device *dev, unsigned epnum)
{
        struct usb_host_config *config = dev->actconfig;
        int i, k;

        if (!config)
                return NULL;
        for (i = 0; i < config->desc.bNumInterfaces; i++) {
                struct usb_interface            *intf;
                struct usb_host_interface       *alt;

                /* only endpoints in current altsetting are active */
                intf = config->interface[i];
                alt = intf->cur_altsetting;

                for (k = 0; k < alt->desc.bNumEndpoints; k++)
                        if (epnum == alt->endpoint[k].desc.bEndpointAddress)
                                return &alt->endpoint[k].desc;
        }

        return NULL;
}

/**
 * usb_driver_claim_interface - bind a driver to an interface
 * @driver: the driver to be bound
 * @iface: the interface to which it will be bound; must be in the
 *      usb device's active configuration
 * @priv: driver data associated with that interface
 *
 * This is used by usb device drivers that need to claim more than one
 * interface on a device when probing (audio and acm are current examples).
 * No device driver should directly modify internal usb_interface or
 * usb_device structure members.
 *
 * Few drivers should need to use this routine, since the most natural
 * way to bind to an interface is to return the private data from
 * the driver's probe() method.
 *
 * Callers must own the driver model's usb bus writelock.  So driver
 * probe() entries don't need extra locking, but other call contexts
 * may need to explicitly claim that lock.
 */
int usb_driver_claim_interface(struct usb_driver *driver, struct usb_interface *iface, void* priv)
{
        struct device *dev = &iface->dev;

        if (dev->driver)
                return -EBUSY;

        dev->driver = &driver->driver;
        usb_set_intfdata(iface, priv);

        /* if interface was already added, bind now; else let
         * the future device_add() bind it, bypassing probe()
         */
        if (!list_empty (&dev->bus_list))
                device_bind_driver(dev);

        return 0;
}

/**
 * usb_driver_release_interface - unbind a driver from an interface
 * @driver: the driver to be unbound
 * @iface: the interface from which it will be unbound
 *
 * This can be used by drivers to release an interface without waiting
 * for their disconnect() methods to be called.  In typical cases this
 * also causes the driver disconnect() method to be called.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 * Callers must own the usb_device serialize semaphore and the driver model's
 * usb bus writelock.  So driver disconnect() entries don't need extra locking,
 * but other call contexts may need to explicitly claim those locks.
 */
void usb_driver_release_interface(struct usb_driver *driver,
                                        struct usb_interface *iface)
{
        struct device *dev = &iface->dev;

        /* this should never happen, don't release something that's not ours */
        if (!dev->driver || dev->driver != &driver->driver)
                return;

        /* don't disconnect from disconnect(), or before dev_add() */
        if (!list_empty (&dev->driver_list) && !list_empty (&dev->bus_list))
                device_release_driver(dev);

        dev->driver = NULL;
        usb_set_intfdata(iface, NULL);
}

/**
 * usb_match_id - find first usb_device_id matching device or interface
 * @interface: the interface of interest
 * @id: array of usb_device_id structures, terminated by zero entry
 *
 * usb_match_id searches an array of usb_device_id's and returns
 * the first one matching the device or interface, or null.
 * This is used when binding (or rebinding) a driver to an interface.
 * Most USB device drivers will use this indirectly, through the usb core,
 * but some layered driver frameworks use it directly.
 * These device tables are exported with MODULE_DEVICE_TABLE, through
 * modutils and "modules.usbmap", to support the driver loading
 * functionality of USB hotplugging.
 *
 * What Matches:
 *
 * The "match_flags" element in a usb_device_id controls which
 * members are used.  If the corresponding bit is set, the
 * value in the device_id must match its corresponding member
 * in the device or interface descriptor, or else the device_id
 * does not match.
 *
 * "driver_info" is normally used only by device drivers,
 * but you can create a wildcard "matches anything" usb_device_id
 * as a driver's "modules.usbmap" entry if you provide an id with
 * only a nonzero "driver_info" field.  If you do this, the USB device
 * driver's probe() routine should use additional intelligence to
 * decide whether to bind to the specified interface.
 * 
 * What Makes Good usb_device_id Tables:
 *
 * The match algorithm is very simple, so that intelligence in
 * driver selection must come from smart driver id records.
 * Unless you have good reasons to use another selection policy,
 * provide match elements only in related groups, and order match
 * specifiers from specific to general.  Use the macros provided
 * for that purpose if you can.
 *
 * The most specific match specifiers use device descriptor
 * data.  These are commonly used with product-specific matches;
 * the USB_DEVICE macro lets you provide vendor and product IDs,
 * and you can also match against ranges of product revisions.
 * These are widely used for devices with application or vendor
 * specific bDeviceClass values.
 *
 * Matches based on device class/subclass/protocol specifications
 * are slightly more general; use the USB_DEVICE_INFO macro, or
 * its siblings.  These are used with single-function devices
 * where bDeviceClass doesn't specify that each interface has
 * its own class. 
 *
 * Matches based on interface class/subclass/protocol are the
 * most general; they let drivers bind to any interface on a
 * multiple-function device.  Use the USB_INTERFACE_INFO
 * macro, or its siblings, to match class-per-interface style 
 * devices (as recorded in bDeviceClass).
 *  
 * Within those groups, remember that not all combinations are
 * meaningful.  For example, don't give a product version range
 * without vendor and product IDs; or specify a protocol without
 * its associated class and subclass.
 */   
const struct usb_device_id *
usb_match_id(struct usb_interface *interface, const struct usb_device_id *id)
{
        struct usb_host_interface *intf;
        struct usb_device *dev;

        /* proc_connectinfo in devio.c may call us with id == NULL. */
        if (id == NULL)
                return NULL;

        intf = interface->cur_altsetting;
        dev = interface_to_usbdev(interface);

        /* It is important to check that id->driver_info is nonzero,
           since an entry that is all zeroes except for a nonzero
           id->driver_info is the way to create an entry that
           indicates that the driver want to examine every
           device and interface. */
        for (; id->idVendor || id->bDeviceClass || id->bInterfaceClass ||
               id->driver_info; id++) {

                if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
                    id->idVendor != dev->descriptor.idVendor)
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
                    id->idProduct != dev->descriptor.idProduct)
                        continue;

                /* No need to test id->bcdDevice_lo != 0, since 0 is never
                   greater than any unsigned number. */
                if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
                    (id->bcdDevice_lo > dev->descriptor.bcdDevice))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
                    (id->bcdDevice_hi < dev->descriptor.bcdDevice))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
                    (id->bDeviceClass != dev->descriptor.bDeviceClass))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
                    (id->bDeviceSubClass!= dev->descriptor.bDeviceSubClass))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
                    (id->bDeviceProtocol != dev->descriptor.bDeviceProtocol))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
                    (id->bInterfaceClass != intf->desc.bInterfaceClass))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
                    (id->bInterfaceSubClass != intf->desc.bInterfaceSubClass))
                        continue;

                if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
                    (id->bInterfaceProtocol != intf->desc.bInterfaceProtocol))
                        continue;

                return id;
        }

        return NULL;
}

/**
 * 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 driver device list and returns a pointer to the interface 
 * with the matching minor.  Note, this only works for devices that share the
 * USB major number.
 */
struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
{
        struct list_head *entry;
        struct device *dev;
        struct usb_interface *intf;

        list_for_each(entry, &drv->driver.devices) {
                dev = container_of(entry, struct device, driver_list);

                /* can't look at usb devices, only interfaces */
                if (dev->driver == &usb_generic_driver)
                        continue;

                intf = to_usb_interface(dev);
                if (intf->minor == -1)
                        continue;
                if (intf->minor == minor)
                        return intf;
        }

        /* no device found that matches */
        return NULL;    
}

static int usb_device_match (struct device *dev, struct device_driver *drv)
{
        struct usb_interface *intf;
        struct usb_driver *usb_drv;
        const struct usb_device_id *id;

        /* check for generic driver, which we don't match any device with */
        if (drv == &usb_generic_driver)
                return 0;

        intf = to_usb_interface(dev);

        usb_drv = to_usb_driver(drv);
        id = usb_drv->id_table;
        
        id = usb_match_id (intf, usb_drv->id_table);
        if (id)
                return 1;

        return 0;
}


#ifdef  CONFIG_HOTPLUG

/*
 * USB hotplugging invokes what /proc/sys/kernel/hotplug says
 * (normally /sbin/hotplug) when USB devices get added or removed.
 *
 * This invokes a user mode policy agent, typically helping to load driver
 * or other modules, configure the device, and more.  Drivers can provide
 * a MODULE_DEVICE_TABLE to help with module loading subtasks.
 *
 * We're called either from khubd (the typical case) or from root hub
 * (init, kapmd, modprobe, rmmod, etc), but the agents need to handle
 * delays in event delivery.  Use sysfs (and DEVPATH) to make sure the
 * device (and this configuration!) are still present.
 */
static int usb_hotplug (struct device *dev, char **envp, int num_envp,
                        char *buffer, int buffer_size)
{
        struct usb_interface *intf;
        struct usb_device *usb_dev;
        char *scratch;
        int i = 0;
        int length = 0;

        if (!dev)
                return -ENODEV;

        /* driver is often null here; dev_dbg() would oops */
        pr_debug ("usb %s: hotplug\n", dev->bus_id);

        /* Must check driver_data here, as on remove driver is always NULL */
        if ((dev->driver == &usb_generic_driver) || 
            (dev->driver_data == &usb_generic_driver_data))
                return 0;

        intf = to_usb_interface(dev);
        usb_dev = interface_to_usbdev (intf);
        
        if (usb_dev->devnum < 0) {
                pr_debug ("usb %s: already deleted?\n", dev->bus_id);
                return -ENODEV;
        }
        if (!usb_dev->bus) {
                pr_debug ("usb %s: bus removed?\n", dev->bus_id);
                return -ENODEV;
        }

        scratch = buffer;

#ifdef  CONFIG_USB_DEVICEFS
        /* If this is available, userspace programs can directly read
         * all the device descriptors we don't tell them about.  Or
         * even act as usermode drivers.
         *
         * FIXME reduce hardwired intelligence here
         */
        envp [i++] = scratch;
        length += snprintf (scratch, buffer_size - length,
                            "DEVICE=/proc/bus/usb/%03d/%03d",
                            usb_dev->bus->busnum, usb_dev->devnum);
        if ((buffer_size - length <= 0) || (i >= num_envp))
                return -ENOMEM;
        ++length;
        scratch += length;
#endif

        /* per-device configurations are common */
        envp [i++] = scratch;
        length += snprintf (scratch, buffer_size - length, "PRODUCT=%x/%x/%x",
                            usb_dev->descriptor.idVendor,
                            usb_dev->descriptor.idProduct,
                            usb_dev->descriptor.bcdDevice);
        if ((buffer_size - length <= 0) || (i >= num_envp))
                return -ENOMEM;
        ++length;
        scratch += length;

        /* class-based driver binding models */
        envp [i++] = scratch;
        length += snprintf (scratch, buffer_size - length, "TYPE=%d/%d/%d",
                            usb_dev->descriptor.bDeviceClass,
                            usb_dev->descriptor.bDeviceSubClass,
                            usb_dev->descriptor.bDeviceProtocol);
        if ((buffer_size - length <= 0) || (i >= num_envp))
                return -ENOMEM;
        ++length;
        scratch += length;

        if (usb_dev->descriptor.bDeviceClass == 0) {
                struct usb_host_interface *alt = intf->cur_altsetting;

                /* 2.4 only exposed interface zero.  in 2.5, hotplug
                 * agents are called for all interfaces, and can use
                 * $DEVPATH/bInterfaceNumber if necessary.
                 */
                envp [i++] = scratch;
                length += snprintf (scratch, buffer_size - length,
                            "INTERFACE=%d/%d/%d",
                            alt->desc.bInterfaceClass,
                            alt->desc.bInterfaceSubClass,
                            alt->desc.bInterfaceProtocol);
                if ((buffer_size - length <= 0) || (i >= num_envp))
                        return -ENOMEM;
                ++length;
                scratch += length;

        }
        envp[i++] = NULL;

        return 0;
}

#else

static int usb_hotplug (struct device *dev, char **envp,
                        int num_envp, char *buffer, int buffer_size)
{
        return -ENODEV;
}

#endif  /* CONFIG_HOTPLUG */

/**
 * 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;

        udev = to_usb_device(dev);

        if (udev->bus && udev->bus->op && udev->bus->op->deallocate)
                udev->bus->op->deallocate(udev);
        usb_destroy_configuration(udev);
        usb_bus_put(udev->bus);
        kfree (udev);
}

/**
 * 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
 * @port: zero 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.
 */
struct usb_device *
usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port)
{
        struct usb_device *dev;

        dev = kmalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return NULL;

        memset(dev, 0, sizeof(*dev));

        bus = usb_bus_get(bus);
        if (!bus) {
                kfree(dev);
                return NULL;
        }

        device_initialize(&dev->dev);
        dev->dev.bus = &usb_bus_type;
        dev->dev.dma_mask = bus->controller->dma_mask;
        dev->dev.driver_data = &usb_generic_driver_data;
        dev->dev.driver = &usb_generic_driver;
        dev->dev.release = usb_release_dev;
        dev->state = USB_STATE_ATTACHED;

        /* 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 bus_id 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->dev.parent = bus->controller;
                sprintf (&dev->dev.bus_id[0], "usb%d", bus->busnum);
        } else {
                /* match any labeling on the hubs; it's one-based */
                if (parent->devpath [0] == '0')
                        snprintf (dev->devpath, sizeof dev->devpath,
                                "%d", port + 1);
                else
                        snprintf (dev->devpath, sizeof dev->devpath,
                                "%s.%d", parent->devpath, port + 1);

                dev->dev.parent = &parent->dev;
                sprintf (&dev->dev.bus_id[0], "%d-%s",
                        bus->busnum, dev->devpath);

                /* hub driver sets up TT records */
        }

        dev->bus = bus;
        dev->parent = parent;
        INIT_LIST_HEAD(&dev->filelist);

        init_MUTEX(&dev->serialize);

        if (dev->bus->op->allocate)
                dev->bus->op->allocate(dev);

        return 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.
 *
 * A pointer to the device with the incremented reference counter is returned.
 */
struct usb_device *usb_get_dev(struct usb_device *dev)
{
        if (dev)
                get_device(&dev->dev);
        return 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);
}

/**
 * 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.
 *
 * A pointer to the interface with the incremented reference counter is
 * returned.
 */
struct usb_interface *usb_get_intf(struct usb_interface *intf)
{
        if (intf)
                get_device(&intf->dev);
        return 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);
}

static struct usb_device *match_device(struct usb_device *dev,
                                       u16 vendor_id, u16 product_id)
{
        struct usb_device *ret_dev = NULL;
        int child;

        dev_dbg(&dev->dev, "check for vendor %04x, product %04x ...\n",
            dev->descriptor.idVendor,
            dev->descriptor.idProduct);

        /* see if this device matches */
        if ((dev->descriptor.idVendor == vendor_id) &&
            (dev->descriptor.idProduct == product_id)) {
                dev_dbg (&dev->dev, "matched this device!\n");
                ret_dev = usb_get_dev(dev);
                goto exit;
        }

        /* look through all of the children of this device */
        for (child = 0; child < dev->maxchild; ++child) {
                if (dev->children[child]) {
                        ret_dev = match_device(dev->children[child],
                                               vendor_id, product_id);
                        if (ret_dev)
                                goto exit;
                }
        }
exit:
        return ret_dev;
}

/**
 * usb_find_device - find a specific usb device in the system
 * @vendor_id: the vendor id of the device to find
 * @product_id: the product id of the device to find
 *
 * Returns a pointer to a struct usb_device if such a specified usb
 * device is present in the system currently.  The usage count of the
 * device will be incremented if a device is found.  Make sure to call
 * usb_put_dev() when the caller is finished with the device.
 *
 * If a device with the specified vendor and product id is not found,
 * NULL is returned.
 */
struct usb_device *usb_find_device(u16 vendor_id, u16 product_id)
{
        struct list_head *buslist;
        struct usb_bus *bus;
        struct usb_device *dev = NULL;
        
        down(&usb_bus_list_lock);
        for (buslist = usb_bus_list.next;
             buslist != &usb_bus_list; 
             buslist = buslist->next) {
                bus = container_of(buslist, struct usb_bus, bus_list);
                if (!bus->root_hub)
                        continue;
                dev = match_device(bus->root_hub, vendor_id, product_id);
                if (dev)
                        goto exit;
        }
exit:
        up(&usb_bus_list_lock);
        return dev;
}

/**
 * usb_get_current_frame_number - return current bus frame number
 * @dev: the device whose bus is being queried
 *
 * Returns the current frame number for the USB host controller
 * used with the given USB device.  This can be used when scheduling
 * isochronous requests.
 *
 * Note that 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 dev->bus->op->get_frame_number (dev);
}

/*-------------------------------------------------------------------*/
/*
 * __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)
{
        struct usb_descriptor_header *header;

        while (size >= sizeof(struct usb_descriptor_header)) {
                header = (struct usb_descriptor_header *)buffer;

                if (header->bLength < 2) {
                        printk(KERN_ERR
                                "%s: bogus descriptor, type %d length %d\n",
                                usbcore_name,
                                header->bDescriptorType, 
                                header->bLength);
                        return -1;
                }

                if (header->bDescriptorType == type) {
                        *ptr = header;
                        return 0;
                }

                buffer += header->bLength;
                size -= header->bLength;
        }
        return -1;
}

/**
 * usb_buffer_alloc - 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 value is 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).
 *
 * These buffers are used with URB_NO_xxx_DMA_MAP set in urb->transfer_flags
 * to avoid behaviors like using "DMA bounce buffers", or tying down I/O
 * mapping hardware for long idle periods.  The implementation varies between
 * platforms, depending on details of how DMA will work to this device.
 * Using these buffers also helps prevent cacheline sharing problems on
 * architectures where CPU caches are not DMA-coherent.
 *
 * When the buffer is no longer used, free it with usb_buffer_free().
 */
void *usb_buffer_alloc (
        struct usb_device *dev,
        size_t size,
        int mem_flags,
        dma_addr_t *dma
)
{
        if (!dev || !dev->bus || !dev->bus->op || !dev->bus->op->buffer_alloc)
                return NULL;
        return dev->bus->op->buffer_alloc (dev->bus, size, mem_flags, dma);
}

/**
 * usb_buffer_free - free memory allocated with usb_buffer_alloc()
 * @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_buffer_alloc(), and the parameters must match
 * those provided in that allocation request. 
 */
void usb_buffer_free (
        struct usb_device *dev,
        size_t size,
        void *addr,
        dma_addr_t dma
)
{
        if (!dev || !dev->bus || !dev->bus->op || !dev->bus->op->buffer_free)
                return;
        dev->bus->op->buffer_free (dev->bus, size, addr, dma);
}

/**
 * usb_buffer_map - create DMA mapping(s) for an urb
 * @urb: urb whose transfer_buffer/setup_packet will be mapped
 *
 * Return value is either null (indicating no buffer could be mapped), or
 * the parameter.  URB_NO_TRANSFER_DMA_MAP and URB_NO_SETUP_DMA_MAP are
 * 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().
 */
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->controller))
                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);
                if (usb_pipecontrol (urb->pipe))
                        urb->setup_dma = dma_map_single (controller,
                                        urb->setup_packet,
                                        sizeof (struct usb_ctrlrequest),
                                        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
                                | URB_NO_SETUP_DMA_MAP);
        return urb;
}

/* 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->controller))
                return;

        if (controller->dma_mask) {
                dma_sync_single (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 (controller,
                                        urb->setup_dma,
                                        sizeof (struct usb_ctrlrequest),
                                        DMA_TO_DEVICE);
        }
}
#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().
 */
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->controller))
                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);
                if (usb_pipecontrol (urb->pipe))
                        dma_unmap_single (controller,
                                        urb->setup_dma,
                                        sizeof (struct usb_ctrlrequest),
                                        DMA_TO_DEVICE);
        }
        urb->transfer_flags &= ~(URB_NO_TRANSFER_DMA_MAP
                                | URB_NO_SETUP_DMA_MAP);
}

/**
 * usb_buffer_map_sg - create scatterlist DMA mapping(s) for an endpoint
 * @dev: device to which the scatterlist will be mapped
 * @pipe: endpoint defining the mapping direction
 * @sg: the scatterlist to map
 * @nents: the number of entries in the scatterlist
 *
 * Return value is either < 0 (indicating no buffers could be mapped), or
 * the number of DMA mapping array entries in the scatterlist.
 *
 * 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 (struct usb_device *dev, unsigned pipe,
                struct scatterlist *sg, int nents)
{
        struct usb_bus          *bus;
        struct device           *controller;

        if (!dev
                        || usb_pipecontrol (pipe)
                        || !(bus = dev->bus)
                        || !(controller = bus->controller)
                        || !controller->dma_mask)
                return -1;

        // FIXME generic api broken like pci, can't report errors
        return dma_map_sg (controller, sg, nents,
                        usb_pipein (pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}

/* 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
 * @pipe: endpoint defining the mapping 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 (struct usb_device *dev, unsigned pipe,
                struct scatterlist *sg, int n_hw_ents)
{
        struct usb_bus          *bus;
        struct device           *controller;

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

        dma_sync_sg (controller, sg, n_hw_ents,
                        usb_pipein (pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}
#endif

/**
 * usb_buffer_unmap_sg - free DMA mapping(s) for a scatterlist
 * @dev: device to which the scatterlist will be mapped
 * @pipe: endpoint defining the mapping 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 (struct usb_device *dev, unsigned pipe,
                struct scatterlist *sg, int n_hw_ents)
{
        struct usb_bus          *bus;
        struct device           *controller;

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

        dma_unmap_sg (controller, sg, n_hw_ents,
                        usb_pipein (pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}

static int usb_generic_suspend(struct device *dev, u32 state)
{
        struct usb_interface *intf;
        struct usb_driver *driver;

        if (dev->driver == &usb_generic_driver)
                return usb_suspend_device (to_usb_device(dev), state);

        if ((dev->driver == NULL) ||
            (dev->driver_data == &usb_generic_driver_data))
                return 0;

        intf = to_usb_interface(dev);
        driver = to_usb_driver(dev->driver);

        if (driver->suspend)
                return driver->suspend(intf, state);
        return 0;
}

static int usb_generic_resume(struct device *dev)
{
        struct usb_interface *intf;
        struct usb_driver *driver;

        /* devices resume through their hub */
        if (dev->driver == &usb_generic_driver)
                return usb_resume_device (to_usb_device(dev));

        if ((dev->driver == NULL) ||
            (dev->driver_data == &usb_generic_driver_data))
                return 0;

        intf = to_usb_interface(dev);
        driver = to_usb_driver(dev->driver);

        if (driver->resume)
                return driver->resume(intf);
        return 0;
}

struct bus_type usb_bus_type = {
        .name =         "usb",
        .match =        usb_device_match,
        .hotplug =      usb_hotplug,
        .suspend =      usb_generic_suspend,
        .resume =       usb_generic_resume,
};

#ifndef MODULE

static int __init usb_setup_disable(char *str)
{
        nousb = 1;
        return 1;
}

/* format to disable USB on kernel command line is: nousb */
__setup("nousb", usb_setup_disable);

#endif

/*
 * for external read access to <nousb>
 */
int usb_disabled(void)
{
        return nousb;
}

/*
 * Init
 */
static int __init usb_init(void)
{
        int retval;
        if (nousb) {
                pr_info ("%s: USB support disabled\n", usbcore_name);
                return 0;
        }

        retval = bus_register(&usb_bus_type);
        if (retval) 
                goto out;
        retval = usb_host_init();
        if (retval)
                goto host_init_failed;
        retval = usb_major_init();
        if (retval)
                goto major_init_failed;
        retval = usbfs_init();
        if (retval)
                goto fs_init_failed;
        retval = usb_hub_init();
        if (retval)
                goto hub_init_failed;

        retval = driver_register(&usb_generic_driver);
        if (!retval)
                goto out;

        usb_hub_cleanup();
hub_init_failed:
        usbfs_cleanup();
fs_init_failed:
        usb_major_cleanup();    
major_init_failed:
        usb_host_cleanup();
host_init_failed:
        bus_unregister(&usb_bus_type);
out:
        return retval;
}

/*
 * Cleanup
 */
static void __exit usb_exit(void)
{
        /* This will matter if shutdown/reboot does exitcalls. */
        if (nousb)
                return;

        driver_unregister(&usb_generic_driver);
        usb_major_cleanup();
        usbfs_cleanup();
        usb_hub_cleanup();
        usb_host_cleanup();
        bus_unregister(&usb_bus_type);
}

subsys_initcall(usb_init);
module_exit(usb_exit);

/*
 * USB may be built into the kernel or be built as modules.
 * These symbols are exported for device (or host controller)
 * driver modules to use.
 */
EXPORT_SYMBOL(usb_epnum_to_ep_desc);

EXPORT_SYMBOL(usb_register);
EXPORT_SYMBOL(usb_deregister);
EXPORT_SYMBOL(usb_disabled);

EXPORT_SYMBOL(usb_alloc_dev);
EXPORT_SYMBOL(usb_put_dev);
EXPORT_SYMBOL(usb_get_dev);
EXPORT_SYMBOL(usb_hub_tt_clear_buffer);

EXPORT_SYMBOL(usb_driver_claim_interface);
EXPORT_SYMBOL(usb_driver_release_interface);
EXPORT_SYMBOL(usb_match_id);
EXPORT_SYMBOL(usb_find_interface);
EXPORT_SYMBOL(usb_ifnum_to_if);
EXPORT_SYMBOL(usb_altnum_to_altsetting);

EXPORT_SYMBOL(usb_reset_device);
EXPORT_SYMBOL(usb_disconnect);

EXPORT_SYMBOL(__usb_get_extra_descriptor);

EXPORT_SYMBOL(usb_find_device);
EXPORT_SYMBOL(usb_get_current_frame_number);

EXPORT_SYMBOL (usb_buffer_alloc);
EXPORT_SYMBOL (usb_buffer_free);

EXPORT_SYMBOL (usb_buffer_map);
#if 0
EXPORT_SYMBOL (usb_buffer_dmasync);
#endif
EXPORT_SYMBOL (usb_buffer_unmap);

EXPORT_SYMBOL (usb_buffer_map_sg);
#if 0
EXPORT_SYMBOL (usb_buffer_dmasync_sg);
#endif
EXPORT_SYMBOL (usb_buffer_unmap_sg);

MODULE_LICENSE("GPL");