drivers/usb/usb-skeleton.c

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

File Facts

System
Linux kernel
Corpus path
drivers/usb/usb-skeleton.c
Extension
.c
Size
15441 bytes
Lines
646
Domain
Driver Families
Bucket
drivers/usb
Inferred role
Driver Families: operation-table or driver-model contract
Status
pattern 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

static const struct file_operations skel_fops = {
	.owner =	THIS_MODULE,
	.read =		skel_read,
	.write =	skel_write,
	.open =		skel_open,
	.release =	skel_release,
	.flush =	skel_flush,
	.llseek =	noop_llseek,
};

/*
 * usb class driver info in order to get a minor number from the usb core,
 * and to have the device registered with the driver core
 */
static struct usb_class_driver skel_class = {
	.name =		"skel%d",
	.fops =		&skel_fops,
	.minor_base =	USB_SKEL_MINOR_BASE,
};

static int skel_probe(struct usb_interface *interface,
		      const struct usb_device_id *id)
{
	struct usb_skel *dev;
	struct usb_endpoint_descriptor *bulk_in, *bulk_out;
	int retval;

	/* allocate memory for our device state and initialize it */
	dev = kzalloc_obj(*dev);
	if (!dev)
		return -ENOMEM;

	kref_init(&dev->kref);
	sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
	mutex_init(&dev->io_mutex);
	spin_lock_init(&dev->err_lock);
	init_usb_anchor(&dev->submitted);
	init_waitqueue_head(&dev->bulk_in_wait);

	dev->udev = usb_get_dev(interface_to_usbdev(interface));
	dev->interface = usb_get_intf(interface);

	/* set up the endpoint information */
	/* use only the first bulk-in and bulk-out endpoints */
	retval = usb_find_common_endpoints(interface->cur_altsetting,
			&bulk_in, &bulk_out, NULL, NULL);
	if (retval) {
		dev_err(&interface->dev,
			"Could not find both bulk-in and bulk-out endpoints\n");
		goto error;
	}

	dev->bulk_in_size = usb_endpoint_maxp(bulk_in);
	dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
	dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
	if (!dev->bulk_in_buffer) {
		retval = -ENOMEM;
		goto error;
	}
	dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!dev->bulk_in_urb) {
		retval = -ENOMEM;
		goto error;
	}

	dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress;

	/* save our data pointer in this interface device */
	usb_set_intfdata(interface, dev);

	/* we can register the device now, as it is ready */
	retval = usb_register_dev(interface, &skel_class);
	if (retval) {
		/* something prevented us from registering this driver */
		dev_err(&interface->dev,
			"Not able to get a minor for this device.\n");
		usb_set_intfdata(interface, NULL);
		goto error;
	}

	/* let the user know what node this device is now attached to */
	dev_info(&interface->dev,
		 "USB Skeleton device now attached to USBSkel-%d",
		 interface->minor);
	return 0;

error:
	/* this frees allocated memory */
	kref_put(&dev->kref, skel_delete);

Annotation

Implementation Notes