drivers/usb/core/message.c

Source file repositories/reference/linux-study-clean/drivers/usb/core/message.c

File Facts

System
Linux kernel
Corpus path
drivers/usb/core/message.c
Extension
.c
Size
77074 bytes
Lines
2522
Domain
Driver Families
Bucket
drivers/usb
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

ret = device_add(&intf->dev);
		if (ret != 0) {
			dev_err(&dev->dev, "device_add(%s) --> %d\n",
				dev_name(&intf->dev), ret);
			continue;
		}
		create_intf_ep_devs(intf);
	}

	usb_autosuspend_device(dev);
	return 0;
}
EXPORT_SYMBOL_GPL(usb_set_configuration);

static LIST_HEAD(set_config_list);
static DEFINE_SPINLOCK(set_config_lock);

struct set_config_request {
	struct usb_device	*udev;
	int			config;
	struct work_struct	work;
	struct list_head	node;
};

/* Worker routine for usb_driver_set_configuration() */
static void driver_set_config_work(struct work_struct *work)
{
	struct set_config_request *req =
		container_of(work, struct set_config_request, work);
	struct usb_device *udev = req->udev;

	usb_lock_device(udev);
	spin_lock(&set_config_lock);
	list_del(&req->node);
	spin_unlock(&set_config_lock);

	if (req->config >= -1)		/* Is req still valid? */
		usb_set_configuration(udev, req->config);
	usb_unlock_device(udev);
	usb_put_dev(udev);
	kfree(req);
}

/* Cancel pending Set-Config requests for a device whose configuration
 * was just changed
 */
static void cancel_async_set_config(struct usb_device *udev)
{
	struct set_config_request *req;

	spin_lock(&set_config_lock);
	list_for_each_entry(req, &set_config_list, node) {
		if (req->udev == udev)
			req->config = -999;	/* Mark as cancelled */
	}
	spin_unlock(&set_config_lock);
}

/**
 * usb_driver_set_configuration - Provide a way for drivers to change device configurations
 * @udev: the device whose configuration is being updated
 * @config: the configuration being chosen.
 * Context: In process context, must be able to sleep
 *
 * Device interface drivers are not allowed to change device configurations.
 * This is because changing configurations will destroy the interface the
 * driver is bound to and create new ones; it would be like a floppy-disk
 * driver telling the computer to replace the floppy-disk drive with a
 * tape drive!
 *
 * Still, in certain specialized circumstances the need may arise.  This
 * routine gets around the normal restrictions by using a work thread to
 * submit the change-config request.
 *
 * Return: 0 if the request was successfully queued, error code otherwise.
 * The caller has no way to know whether the queued request will eventually
 * succeed.
 */
int usb_driver_set_configuration(struct usb_device *udev, int config)
{
	struct set_config_request *req;

	req = kmalloc_obj(*req);
	if (!req)
		return -ENOMEM;
	req->udev = udev;
	req->config = config;
	INIT_WORK(&req->work, driver_set_config_work);

	spin_lock(&set_config_lock);

Annotation

Implementation Notes