drivers/usb/misc/legousbtower.c

File Facts

System

Linux kernel

Corpus path

drivers/usb/misc/legousbtower.c

Extension

.c

Size

24772 bytes

Lines

880

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.

• 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.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/kernel.h
• linux/errno.h
• linux/slab.h
• linux/module.h
• linux/completion.h
• linux/mutex.h
• linux/uaccess.h
• linux/usb.h
• linux/poll.h

Detected Declarations

• struct tower_reset_reply
• struct tower_get_version_reply
• struct lego_usb_tower
• function lego_usb_tower_debug_data
• function tower_delete
• function tower_open
• function tower_release
• function tower_check_for_read_packet
• function tower_poll
• function tower_llseek
• function tower_read
• function tower_write
• function tower_interrupt_in_callback
• function tower_interrupt_out_callback
• function tower_probe
• function tower_disconnect

Annotated Snippet

static const struct file_operations tower_fops = {
	.owner =	THIS_MODULE,
	.read  =	tower_read,
	.write =	tower_write,
	.open =		tower_open,
	.release =	tower_release,
	.poll =		tower_poll,
	.llseek =	tower_llseek,
};

static char *legousbtower_devnode(const struct device *dev, umode_t *mode)
{
	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
}

/*
 * 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 tower_class = {
	.name =		"legousbtower%d",
	.devnode = 	legousbtower_devnode,
	.fops =		&tower_fops,
	.minor_base =	LEGO_USB_TOWER_MINOR_BASE,
};


/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver tower_driver = {
	.name =		"legousbtower",
	.probe =	tower_probe,
	.disconnect =	tower_disconnect,
	.id_table =	tower_table,
};


/*
 *	lego_usb_tower_debug_data
 */
static inline void lego_usb_tower_debug_data(struct device *dev,
					     const char *function, int size,
					     const unsigned char *data)
{
	dev_dbg(dev, "%s - length = %d, data = %*ph\n",
		function, size, size, data);
}


/*
 *	tower_delete
 */
static inline void tower_delete(struct lego_usb_tower *dev)
{
	/* free data structures */
	usb_free_urb(dev->interrupt_in_urb);
	usb_free_urb(dev->interrupt_out_urb);
	kfree(dev->read_buffer);
	kfree(dev->interrupt_in_buffer);
	kfree(dev->interrupt_out_buffer);
	usb_put_dev(dev->udev);
	kfree(dev);
}


/*
 *	tower_open
 */
static int tower_open(struct inode *inode, struct file *file)
{
	struct lego_usb_tower *dev = NULL;
	int subminor;
	int retval = 0;
	struct usb_interface *interface;
	struct tower_reset_reply reset_reply;
	int result;

	nonseekable_open(inode, file);
	subminor = iminor(inode);

	interface = usb_find_interface(&tower_driver, subminor);
	if (!interface) {
		pr_err("error, can't find device for minor %d\n", subminor);
		retval = -ENODEV;
		goto exit;
	}

	dev = usb_get_intfdata(interface);
	if (!dev) {
		retval = -ENODEV;
		goto exit;

Annotation

• Immediate include surface: `linux/kernel.h`, `linux/errno.h`, `linux/slab.h`, `linux/module.h`, `linux/completion.h`, `linux/mutex.h`, `linux/uaccess.h`, `linux/usb.h`.
• Detected declarations: `struct tower_reset_reply`, `struct tower_get_version_reply`, `struct lego_usb_tower`, `function lego_usb_tower_debug_data`, `function tower_delete`, `function tower_open`, `function tower_release`, `function tower_check_for_read_packet`, `function tower_poll`, `function tower_llseek`.
• Atlas domain: Driver Families / drivers/usb.
• Implementation status: pattern implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.