usb.c

基于S3CEB2410平台LINUX操作系统下 USB驱动源代码

/*
 * 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 (kernel hotplug, usb_device_id)
 * (C) Copyright Yggdrasil Computing, Inc. 2000
 *     (usb_device_id matching changes by Adam J. Richter)
 *
 * 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>
#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/devfs_fs_kernel.h>
#include <linux/spinlock.h>

#ifdef CONFIG_USB_DEBUG
	#define DEBUG
#else
	#undef DEBUG
#endif
#include <linux/usb.h>

static const int usb_bandwidth_option =
#ifdef CONFIG_USB_BANDWIDTH
				1;
#else
				0;
#endif

extern int  usb_hub_init(void);
extern void usb_hub_cleanup(void);

/*
 * Prototypes for the device driver probing/loading functions
 */
static void usb_find_drivers(struct usb_device *);
static int  usb_find_interface_driver(struct usb_device *, unsigned int);
static void usb_check_support(struct usb_device *);

/*
 * We have a per-interface "registered driver" list.
 */
LIST_HEAD(usb_driver_list);
LIST_HEAD(usb_bus_list);
struct semaphore usb_bus_list_lock;

devfs_handle_t usb_devfs_handle;	/* /dev/usb dir. */

static struct usb_busmap busmap;

static struct usb_driver *usb_minors[16];

/**
 *	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.
 */
int usb_register(struct usb_driver *new_driver)
{
	if (new_driver->fops != NULL) {
		if (usb_minors[new_driver->minor/16]) {
			 err("error registering %s driver", new_driver->name);
			return -EINVAL;
		}
		usb_minors[new_driver->minor/16] = new_driver;
	}

	info("registered new driver %s", new_driver->name);

	init_MUTEX(&new_driver->serialize);

	/* Add it to the list of known drivers */
	list_add_tail(&new_driver->driver_list, &usb_driver_list);

	usb_scan_devices();

	return 0;
}

/**
 *	usb_scan_devices - scans all unclaimed USB interfaces
 *
 *	Goes through all unclaimed USB interfaces, and offers them to all
 *	registered USB drivers through the 'probe' function.
 *	This will automatically be called after usb_register is called.
 *	It is called by some of the USB subsystems after one of their subdrivers
 *	are registered.
 */
void usb_scan_devices(void)
{
	struct list_head *tmp;

	down (&usb_bus_list_lock);
	tmp = usb_bus_list.next;
	while (tmp != &usb_bus_list) {
		struct usb_bus *bus = list_entry(tmp,struct usb_bus, bus_list);

		tmp = tmp->next;
		usb_check_support(bus->root_hub);
	}
	up (&usb_bus_list_lock);
}

/*
 * This function is part of a depth-first search down the device tree,
 * removing any instances of a device driver.
 */
static void usb_drivers_purge(struct usb_driver *driver,struct usb_device *dev)
{
	int i;

	if (!dev) {
		err("null device being purged!!!");
		return;
	}

	for (i=0; i<USB_MAXCHILDREN; i++)
		if (dev->children[i])
			usb_drivers_purge(driver, dev->children[i]);

	if (!dev->actconfig)
		return;
			
	for (i = 0; i < dev->actconfig->bNumInterfaces; i++) {
		struct usb_interface *interface = &dev->actconfig->interface[i];
		
		if (interface->driver == driver) {
			down(&driver->serialize);
			driver->disconnect(dev, interface->private_data);
			up(&driver->serialize);
			/* if driver->disconnect didn't release the interface */
			if (interface->driver)
				usb_driver_release_interface(driver, interface);
			/*
			 * This will go through the list looking for another
			 * driver that can handle the device
			 */
			usb_find_interface_driver(dev, i);
		}
	}
}

/**
 *	usb_deregister - unregister a USB driver
 *	@driver: USB operations of the driver to unregister
 *
 *	Unlinks the specified driver from the internal USB driver list.
 */
void usb_deregister(struct usb_driver *driver)
{
	struct list_head *tmp;

	info("deregistering driver %s", driver->name);
	if (driver->fops != NULL)
		usb_minors[driver->minor/16] = NULL;

	/*
	 * first we remove the driver, to be sure it doesn't get used by
	 * another thread while we are stepping through removing entries
	 */
	list_del(&driver->driver_list);

	down (&usb_bus_list_lock);
	tmp = usb_bus_list.next;
	while (tmp != &usb_bus_list) {
		struct usb_bus *bus = list_entry(tmp,struct usb_bus,bus_list);

		tmp = tmp->next;
		usb_drivers_purge(driver, bus->root_hub);
	}
	up (&usb_bus_list_lock);
}

struct usb_interface *usb_ifnum_to_if(struct usb_device *dev, unsigned ifnum)
{
	int i;

	for (i = 0; i < dev->actconfig->bNumInterfaces; i++)
		if (dev->actconfig->interface[i].altsetting[0].bInterfaceNumber == ifnum)
			return &dev->actconfig->interface[i];

	return NULL;
}

struct usb_endpoint_descriptor *usb_epnum_to_ep_desc(struct usb_device *dev, unsigned epnum)
{
	int i, j, k;

	for (i = 0; i < dev->actconfig->bNumInterfaces; i++)
		for (j = 0; j < dev->actconfig->interface[i].num_altsetting; j++)
			for (k = 0; k < dev->actconfig->interface[i].altsetting[j].bNumEndpoints; k++)
				if (epnum == dev->actconfig->interface[i].altsetting[j].endpoint[k].bEndpointAddress)
					return &dev->actconfig->interface[i].altsetting[j].endpoint[k];

	return NULL;
}

/*
 * usb_calc_bus_time:
 *
 * returns (approximate) USB bus time in nanoseconds for a USB transaction.
 */
static long usb_calc_bus_time (int low_speed, int input_dir, int isoc, int bytecount)
{
	unsigned long	tmp;

	if (low_speed)		/* no isoc. here */
	{
		if (input_dir)
		{
			tmp = (67667L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (64060L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
		}
		else
		{
			tmp = (66700L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (64107L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
		}
	}

	/* for full-speed: */

	if (!isoc)		/* Input or Output */
	{
		tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
		return (9107L + BW_HOST_DELAY + tmp);
	} /* end not Isoc */

	/* for isoc: */

	tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
	return (((input_dir) ? 7268L : 6265L) + BW_HOST_DELAY + tmp);
}

/*
 * usb_check_bandwidth():
 *
 * old_alloc is from host_controller->bandwidth_allocated in microseconds;
 * bustime is from calc_bus_time(), but converted to microseconds.
 *
 * returns <bustime in us> if successful,
 * or USB_ST_BANDWIDTH_ERROR if bandwidth request fails.
 *
 * FIXME:
 * This initial implementation does not use Endpoint.bInterval
 * in managing bandwidth allocation.
 * It probably needs to be expanded to use Endpoint.bInterval.
 * This can be done as a later enhancement (correction).
 * This will also probably require some kind of
 * frame allocation tracking...meaning, for example,
 * that if multiple drivers request interrupts every 10 USB frames,
 * they don't all have to be allocated at
 * frame numbers N, N+10, N+20, etc.  Some of them could be at
 * N+11, N+21, N+31, etc., and others at
 * N+12, N+22, N+32, etc.
 * However, this first cut at USB bandwidth allocation does not
 * contain any frame allocation tracking.
 */
int usb_check_bandwidth (struct usb_device *dev, struct urb *urb)
{
	int		new_alloc;
	int		old_alloc = dev->bus->bandwidth_allocated;
	unsigned int	pipe = urb->pipe;
	long		bustime;

	bustime = usb_calc_bus_time (usb_pipeslow(pipe), usb_pipein(pipe),
			usb_pipeisoc(pipe), usb_maxpacket(dev, pipe, usb_pipeout(pipe)));
	if (usb_pipeisoc(pipe))
		bustime = NS_TO_US(bustime) / urb->number_of_packets;
	else
		bustime = NS_TO_US(bustime);

	new_alloc = old_alloc + (int)bustime;
		/* what new total allocated bus time would be */

	if (new_alloc > FRAME_TIME_MAX_USECS_ALLOC)
		dbg("usb-check-bandwidth %sFAILED: was %u, would be %u, bustime = %ld us",
			usb_bandwidth_option ? "" : "would have ",
			old_alloc, new_alloc, bustime);

	if (!usb_bandwidth_option)	/* don't enforce it */
		return (bustime);
	return (new_alloc <= FRAME_TIME_MAX_USECS_ALLOC) ? bustime : USB_ST_BANDWIDTH_ERROR;
}

void usb_claim_bandwidth (struct usb_device *dev, struct urb *urb, int bustime, int isoc)
{
	dev->bus->bandwidth_allocated += bustime;
	if (isoc)
		dev->bus->bandwidth_isoc_reqs++;
	else
		dev->bus->bandwidth_int_reqs++;
	urb->bandwidth = bustime;

#ifdef USB_BANDWIDTH_MESSAGES
	dbg("bandwidth alloc increased by %d to %d for %d requesters",
		bustime,
		dev->bus->bandwidth_allocated,
		dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
}

/*
 * usb_release_bandwidth():
 *
 * called to release a pipe's bandwidth (in microseconds)
 */
void usb_release_bandwidth(struct usb_device *dev, struct urb *urb, int isoc)
{
	dev->bus->bandwidth_allocated -= urb->bandwidth;
	if (isoc)
		dev->bus->bandwidth_isoc_reqs--;
	else
		dev->bus->bandwidth_int_reqs--;

#ifdef USB_BANDWIDTH_MESSAGES
	dbg("bandwidth alloc reduced by %d to %d for %d requesters",
		urb->bandwidth,
		dev->bus->bandwidth_allocated,
		dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
	urb->bandwidth = 0;
}

static void usb_bus_get(struct usb_bus *bus)
{
	atomic_inc(&bus->refcnt);
}

static void usb_bus_put(struct usb_bus *bus)
{
	if (atomic_dec_and_test(&bus->refcnt))
		kfree(bus);
}

/**
 *	usb_alloc_bus - creates a new USB host controller structure
 *	@op: pointer to a struct usb_operations that this bus structure should use
 *
 *	Creates a USB host controller bus structure with the specified 
 *	usb_operations and initializes all the necessary internal objects.
 *	(For use only by USB Host Controller Drivers.)
 *
 *	If no memory is available, NULL is returned.
 *
 *	The caller should call usb_free_bus() when it is finished with the structure.
 */
struct usb_bus *usb_alloc_bus(struct usb_operations *op)
{
	struct usb_bus *bus;

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

	memset(&bus->devmap, 0, sizeof(struct usb_devmap));

#ifdef DEVNUM_ROUND_ROBIN
	bus->devnum_next = 1;
#endif /* DEVNUM_ROUND_ROBIN */

	bus->op = op;
	bus->root_hub = NULL;
	bus->hcpriv = NULL;
	bus->busnum = -1;
	bus->bandwidth_allocated = 0;
	bus->bandwidth_int_reqs  = 0;
	bus->bandwidth_isoc_reqs = 0;

	INIT_LIST_HEAD(&bus->bus_list);
	INIT_LIST_HEAD(&bus->inodes);

	atomic_set(&bus->refcnt, 1);

	return bus;
}

/**
 *	usb_free_bus - frees the memory used by a bus structure
 *	@bus: pointer to the bus to free
 *
 *	(For use only by USB Host Controller Drivers.)
 */
void usb_free_bus(struct usb_bus *bus)
{
	if (!bus)
		return;

	usb_bus_put(bus);
}

/**
 *	usb_register_bus - registers the USB host controller with the usb core
 *	@bus: pointer to the bus to register
 *
 *	(For use only by USB Host Controller Drivers.)
 */
void usb_register_bus(struct usb_bus *bus)
{
	int busnum;

	down (&usb_bus_list_lock);
	busnum = find_next_zero_bit(busmap.busmap, USB_MAXBUS, 1);
	if (busnum < USB_MAXBUS) {
		set_bit(busnum, busmap.busmap);
		bus->busnum = busnum;
	} else
		warn("too many buses");

	usb_bus_get(bus);

	/* Add it to the list of buses */
	list_add(&bus->bus_list, &usb_bus_list);
	up (&usb_bus_list_lock);

	usbdevfs_add_bus(bus);

	info("new USB bus registered, assigned bus number %d", bus->busnum);
}

/**
 *	usb_deregister_bus - deregisters the USB host controller
 *	@bus: pointer to the bus to deregister
 *
 *	(For use only by USB Host Controller Drivers.)
 */
void usb_deregister_bus(struct usb_bus *bus)
{
	info("USB bus %d deregistered", bus->busnum);

	/*
	 * NOTE: make sure that all the devices are removed by the
	 * controller code, as well as having it call this when cleaning
	 * itself up
	 */
	down (&usb_bus_list_lock);
	list_del(&bus->bus_list);
	up (&usb_bus_list_lock);

	usbdevfs_remove_bus(bus);

	clear_bit(bus->busnum, busmap.busmap);

	usb_bus_put(bus);
}

/*
 * This function is for doing a depth-first search for devices which
 * have support, for dynamic loading of driver modules.
 */