path: root/drivers/usb/core/usb.c

/*
 * drivers/usb/core/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 2000-2004
 * (C) Copyright Yggdrasil Computing, Inc. 2000
 *     (usb_device_id matching changes by Adam J. Richter)
 * (C) Copyright Greg Kroah-Hartman 2002-2003
 *
 * 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/module.h>
#include <linux/moduleparam.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/spinlock.h>
#include <linux/errno.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>

#include <asm/io.h>
#include <linux/scatterlist.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>

#include "usb.h"


const char *usbcore_name = "usbcore";

static int nousb;	/* Disable USB when built into kernel image */

#ifdef	CONFIG_USB_SUSPEND
static int usb_autosuspend_delay = 2;		/* Default delay value,
						 * in seconds */
module_param_named(autosuspend, usb_autosuspend_delay, int, 0644);
MODULE_PARM_DESC(autosuspend, "default autosuspend delay");

#else
#define usb_autosuspend_delay		0
#endif


/**
 * usb_find_alt_setting() - Given a configuration, find the alternate setting
 * for the given interface.
 * @config: the configuration to search (not necessarily the current config).
 * @iface_num: interface number to search in
 * @alt_num: alternate interface setting number to search for.
 *
 * Search the configuration's interface cache for the given alt setting.
 */
struct usb_host_interface *usb_find_alt_setting(
		struct usb_host_config *config,
		unsigned int iface_num,
		unsigned int alt_num)
{
	struct usb_interface_cache *intf_cache = NULL;
	int i;

	for (i = 0; i < config->desc.bNumInterfaces; i++) {
		if (config->intf_cache[i]->altsetting[0].desc.bInterfaceNumber
				== iface_num) {
			intf_cache = config->intf_cache[i];
			break;
		}
	}
	if (!intf_cache)
		return NULL;
	for (i = 0; i < intf_cache->num_altsetting; i++)
		if (intf_cache->altsetting[i].desc.bAlternateSetting == alt_num)
			return &intf_cache->altsetting[i];

	printk(KERN_DEBUG "Did not find alt setting %u for intf %u, "
			"config %u\n", alt_num, iface_num,
			config->desc.bConfigurationValue);
	return NULL;
}
EXPORT_SYMBOL_GPL(usb_find_alt_setting);

/**
 * usb_ifnum_to_if - get the interface object with a given interface number
 * @dev: the device whose current configuration is considered
 * @ifnum: the desired interface
 *
 * This walks the device descriptor for the currently active configuration
 * and returns a pointer to the interface with that particular interface
 * number, or null.
 *
 * Note that configuration descriptors are not required to assign interface
 * numbers sequentially, so that it would be incorrect to assume that
 * the first interface in that descriptor corresponds to interface zero.
 * This routine helps device drivers avoid such mistakes.
 * However, you should make sure that you do the right thing with any
 * alternate settings available for this interfaces.
 *
 * Don't call this function unless you are bound to one of the interfaces
 * on this device or you have locked the device!
 */
struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev,
				      unsigned ifnum)
{
	struct usb_host_config *config = dev->actconfig;
	int i;

	if (!config)
		return NULL;
	for (i = 0; i < config->desc.bNumInterfaces; i++)
		if (config->interface[i]->altsetting[0]
				.desc.bInterfaceNumber == ifnum)
			return config->interface[i];

	return NULL;
}
EXPORT_SYMBOL_GPL(usb_ifnum_to_if);

/**
 * usb_altnum_to_altsetting - get the altsetting structure with a given alternate setting number.
 * @intf: the interface containing the altsetting in question
 * @altnum: the desired alternate setting number
 *
 * This searches the altsetting array of the specified interface for
 * an entry with the correct bAlternateSetting value and returns a pointer
 * to that entry, or null.
 *
 * Note that altsettings need not be stored sequentially by number, so
 * it would be incorrect to assume that the first altsetting entry in
 * the array corresponds to altsetting zero.  This routine helps device
 * drivers avoid such mistakes.
 *
 * Don't call this function unless you are bound to the intf interface
 * or you have locked the device!
 */
struct usb_host_interface *usb_altnum_to_altsetting(
					const struct usb_interface *intf,
					unsigned int altnum)
{
	int i;

	for (i = 0; i < intf->num_altsetting; i++) {
		if (intf->altsetting[i].desc.bAlternateSetting == altnum)
			return &intf->altsetting[i];
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(usb_altnum_to_altsetting);

struct find_interface_arg {
	int minor;
	struct device