usb.c

h内核

	intf = to_usb_interface(dev);
	usb_drv = to_usb_driver(drv);
	
	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;
	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;
	}

#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
	 */
	if (add_hotplug_env_var(envp, num_envp, &i,
				buffer, buffer_size, &length,
				"DEVICE=/proc/bus/usb/%03d/%03d",
				usb_dev->bus->busnum, usb_dev->devnum))
		return -ENOMEM;
#endif

	/* per-device configurations are common */
	if (add_hotplug_env_var(envp, num_envp, &i,
				buffer, buffer_size, &length,
				"PRODUCT=%x/%x/%x",
				le16_to_cpu(usb_dev->descriptor.idVendor),
				le16_to_cpu(usb_dev->descriptor.idProduct),
				le16_to_cpu(usb_dev->descriptor.bcdDevice)))
		return -ENOMEM;

	/* class-based driver binding models */
	if (add_hotplug_env_var(envp, num_envp, &i,
				buffer, buffer_size, &length,
				"TYPE=%d/%d/%d",
				usb_dev->descriptor.bDeviceClass,
				usb_dev->descriptor.bDeviceSubClass,
				usb_dev->descriptor.bDeviceProtocol))
		return -ENOMEM;

	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.
		 */
		if (add_hotplug_env_var(envp, num_envp, &i,
					buffer, buffer_size, &length,
					"INTERFACE=%d/%d/%d",
					alt->desc.bInterfaceClass,
					alt->desc.bInterfaceSubClass,
					alt->desc.bInterfaceProtocol))
			return -ENOMEM;
	}

	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);

	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
 * @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.
 */
struct usb_device *
usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
{
	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;

	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 */
	dev->ep_in[0] = dev->ep_out[0] = &dev->ep0;

	/* 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", port1);
		else
			snprintf (dev->devpath, sizeof dev->devpath,
				"%s.%d", parent->devpath, port1);

		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);

	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);
}


/*			USB device locking
 *
 * Although locking USB devices should be straightforward, it is
 * complicated by the way the driver-model core works.  When a new USB
 * driver is registered or unregistered, the core will automatically
 * probe or disconnect all matching interfaces on all USB devices while
 * holding the USB subsystem writelock.  There's no good way for us to
 * tell which devices will be used or to lock them beforehand; our only
 * option is to effectively lock all the USB devices.
 *
 * We do that by using a private rw-semaphore, usb_all_devices_rwsem.
 * When locking an individual device you must first acquire the rwsem's
 * readlock.  When a driver is registered or unregistered the writelock
 * must be held.  These actions are encapsulated in the subroutines
 * below, so all a driver needs to do is call usb_lock_device() and
 * usb_unlock_device().
 *
 * 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 problem is that
 * usb_lock_device() must not be called to lock a second device since it
 * would acquire the rwsem's readlock reentrantly, leading to deadlock if
 * another thread was waiting for the writelock.  The solution is simple:
 *
 *	When locking more than one device, call usb_lock_device()
 *	to lock the first one.  Lock the others by calling
 *	down(&udev->serialize) directly.
 *
 *	When unlocking multiple devices, use up(&udev->serialize)
 *	to unlock all but the last one.  Unlock the last one by
 *	calling usb_unlock_device().
 *
 *	When locking both a device and its parent, always lock the
 *	the parent first.
 */

/**
 * usb_lock_device - acquire the lock for a usb device structure
 * @udev: device that's being locked
 *
 * Use this routine when you don't hold any other device locks;
 * to acquire nested inner locks call down(&udev->serialize) directly.
 * This is necessary for proper interaction with usb_lock_all_devices().
 */
void usb_lock_device(struct usb_device *udev)
{
	down_read(&usb_all_devices_rwsem);
	down(&udev->serialize);
}

/**
 * usb_trylock_device - attempt to acquire the lock for a usb device structure
 * @udev: device that's being locked
 *
 * Don't use this routine if you already hold a device lock;
 * use down_trylock(&udev->serialize) instead.
 * This is necessary for proper interaction with usb_lock_all_devices().
 *
 * Returns 1 if successful, 0 if contention.
 */
int usb_trylock_device(struct usb_device *udev)
{
	if (!down_read_trylock(&usb_all_devices_rwsem))
		return 0;
	if (down_trylock(&udev->serialize)) {
		up_read(&usb_all_devices_rwsem);
		return 0;
	}
	return 1;
}

/**
 * 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()
 * callback will block waiting for a device reset to complete.
 *
 * Returns a negative error code for failure, otherwise 1 or 0 to indicate
 * that the device will or will not have to be unlocked.  (0 can be
 * returned when an interface is given and is BINDING, because in that
 * case the driver already owns the device lock.)
 */
int usb_lock_device_for_reset(struct usb_device *udev,
		struct usb_interface *iface)
{
	if (udev->state == USB_STATE_NOTATTACHED)
		return -ENODEV;
	if (udev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;
	if (iface) {
		switch (iface->condition) {
		  case USB_INTERFACE_BINDING:
			return 0;
		  case USB_INTERFACE_BOUND:
			break;
		  default:
			return -EINTR;
		}
	}

	while (!usb_trylock_device(udev)) {
		msleep(15);
		if (udev->state == USB_STATE_NOTATTACHED)
			return -ENODEV;
		if (udev->state == USB_STATE_SUSPENDED)
			return -EHOSTUNREACH;
		if (iface && iface->condition != USB_INTERFACE_BOUND)
			return -EINTR;
	}
	return 1;
}

/**
 * usb_unlock_device - release the lock for a usb device structure
 * @udev: device that's being unlocked
 *
 * Use this routine when releasing the only device lock you hold;
 * to release inner nested locks call up(&udev->serialize) directly.
 * This is necessary for proper interaction with usb_lock_all_devices().
 */
void usb_unlock_device(struct usb_device *udev)
{
	up(&udev->serialize);
	up_read(&usb_all_devices_rwsem);
}

/**
 * usb_lock_all_devices - acquire the lock for all usb device structures
 *
 * This is necessary when registering a new driver or probing a bus,
 * since the driver-model core may try to use any usb_device.
 */
void usb_lock_all_devices(void)
{
	down_write(&usb_all_devices_rwsem);
}

/**
 * usb_unlock_all_devices - release the lock for all usb device structures
 */
void usb_unlock_all_devices(void)
{
	up_write(&usb_all_devices_rwsem);
}


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",
	    le16_to_cpu(dev->descriptor.idVendor),
	    le16_to_cpu(dev->descriptor.idProduct));

	/* see if this device matches */
	if ((vendor_id == le16_to_cpu(dev->descriptor.idVendor)) &&
	    (product_id == le16_to_cpu(dev->descriptor.idProduct))) {
		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]) {
			down(&dev->children[child]->serialize);
			ret_dev = match_device(dev->children[child],
					       vendor_id, product_id);
			up(&dev->children[child]->serialize);
			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;
		usb_lock_device(bus->root_hub);
		dev = match_device(bus->root_hub, vendor_id, product_id);
		usb_unlock_device(bus->root_hub);
		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