usb.c

linux core 函数例程

	if (config->bNumInterfaces > USB_MAXINTERFACES) {
		warn("too many interfaces");
		return -1;
	}

	config->interface = (struct usb_interface *)
		kmalloc(config->bNumInterfaces *
		sizeof(struct usb_interface), GFP_KERNEL);
	dbg("kmalloc IF %p, numif %i", config->interface, config->bNumInterfaces);
	if (!config->interface) {
		err("out of memory");
		return -1;	
	}

	memset(config->interface, 0,
	       config->bNumInterfaces * sizeof(struct usb_interface));

	buffer += config->bLength;
	size -= config->bLength;
	
	config->extra = NULL;
	config->extralen = 0;

	for (i = 0; i < config->bNumInterfaces; i++) {
		int numskipped, len;
		char *begin;

		/* Skip over the rest of the Class Specific or Vendor */
		/*  Specific descriptors */
		begin = buffer;
		numskipped = 0;
		while (size >= sizeof(struct usb_descriptor_header)) {
			header = (struct usb_descriptor_header *)buffer;

			if ((header->bLength > size) || (header->bLength < 2)) {
				err("invalid descriptor length of %d", header->bLength);
				return -1;
			}

			/* If we find another "proper" descriptor then we're done  */
			if ((header->bDescriptorType == USB_DT_ENDPOINT) ||
			    (header->bDescriptorType == USB_DT_INTERFACE) ||
			    (header->bDescriptorType == USB_DT_CONFIG) ||
			    (header->bDescriptorType == USB_DT_DEVICE))
				break;

			dbg("skipping descriptor 0x%X", header->bDescriptorType);
			numskipped++;

			buffer += header->bLength;
			size -= header->bLength;
		}
		if (numskipped)
			dbg("skipped %d class/vendor specific endpoint descriptors", numskipped);

		/* Copy any unknown descriptors into a storage area for */
		/*  drivers to later parse */
		len = (int)(buffer - begin);
		if (len) {
			if (config->extralen) {
				warn("extra config descriptor");
			} else {
				config->extra = kmalloc(len, GFP_KERNEL);
				if (!config->extra) {
					err("couldn't allocate memory for config extra descriptors");
					config->extralen = 0;
					return -1;
				}

				memcpy(config->extra, begin, len);
				config->extralen = len;
			}
		}

		retval = usb_parse_interface(config->interface + i, buffer, size);
		if (retval < 0)
			return retval;

		buffer += retval;
		size -= retval;
	}

	return size;
}

// hub-only!! ... and only exported for reset/reinit path.
// otherwise used internally on disconnect/destroy path
void usb_destroy_configuration(struct usb_device *dev)
{
	int c, i, j, k;
	
	if (!dev->config)
		return;

	if (dev->rawdescriptors) {
		for (i = 0; i < dev->descriptor.bNumConfigurations; i++)
			kfree(dev->rawdescriptors[i]);

		kfree(dev->rawdescriptors);
	}

	for (c = 0; c < dev->descriptor.bNumConfigurations; c++) {
		struct usb_config_descriptor *cf = &dev->config[c];

		if (!cf->interface)
			break;

		for (i = 0; i < cf->bNumInterfaces; i++) {
			struct usb_interface *ifp =
				&cf->interface[i];
				
			if (!ifp->altsetting)
				break;

			for (j = 0; j < ifp->num_altsetting; j++) {
				struct usb_interface_descriptor *as =
					&ifp->altsetting[j];
					
				if(as->extra) {
					kfree(as->extra);
				}

				if (!as->endpoint)
					break;
					
				for(k = 0; k < as->bNumEndpoints; k++) {
					if(as->endpoint[k].extra) {
						kfree(as->endpoint[k].extra);
					}
				}	
				kfree(as->endpoint);
			}

			kfree(ifp->altsetting);
		}
		kfree(cf->interface);
	}
	kfree(dev->config);
}

/* for returning string descriptors in UTF-16LE */
static int ascii2utf (char *ascii, __u8 *utf, int utfmax)
{
	int retval;

	for (retval = 0; *ascii && utfmax > 1; utfmax -= 2, retval += 2) {
		*utf++ = *ascii++ & 0x7f;
		*utf++ = 0;
	}
	return retval;
}

/*
 * root_hub_string is used by each host controller's root hub code,
 * so that they're identified consistently throughout the system.
 */
int usb_root_hub_string (int id, int serial, char *type, __u8 *data, int len)
{
	char buf [30];

	// assert (len > (2 * (sizeof (buf) + 1)));
	// assert (strlen (type) <= 8);

	// language ids
	if (id == 0) {
		*data++ = 4; *data++ = 3;	/* 4 bytes data */
		*data++ = 0; *data++ = 0;	/* some language id */
		return 4;

	// serial number
	} else if (id == 1) {
		sprintf (buf, "%x", serial);

	// product description
	} else if (id == 2) {
		sprintf (buf, "USB %s Root Hub", type);

	// id 3 == vendor description

	// unsupported IDs --> "stall"
	} else
	    return 0;

	data [0] = 2 + ascii2utf (buf, data + 2, len - 2);
	data [1] = 3;
	return data [0];
}

/*
 * __usb_get_extra_descriptor() finds a descriptor of specific type in the
 * extra field of the interface and endpoint descriptor structs.
 */

int __usb_get_extra_descriptor(char *buffer, unsigned size, unsigned char type, void **ptr)
{
	struct usb_descriptor_header *header;

	while (size >= sizeof(struct usb_descriptor_header)) {
		header = (struct usb_descriptor_header *)buffer;

		if (header->bLength < 2) {
			err("invalid descriptor length of %d", header->bLength);
			return -1;
		}

		if (header->bDescriptorType == type) {
			*ptr = header;
			return 0;
		}

		buffer += header->bLength;
		size -= header->bLength;
	}
	return -1;
}

/**
 * usb_disconnect - disconnect a device (usbcore-internal)
 * @pdev: pointer to device being disconnected
 * Context: !in_interrupt ()
 *
 * Something got disconnected. Get rid of it, and all of its children.
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 */
void usb_disconnect(struct usb_device **pdev)
{
	struct usb_device * dev = *pdev;
	int i;

	if (!dev)
		return;

	*pdev = NULL;

	info("USB disconnect on device %d", dev->devnum);

	if (dev->actconfig) {
		for (i = 0; i < dev->actconfig->bNumInterfaces; i++) {
			struct usb_interface *interface = &dev->actconfig->interface[i];
			struct usb_driver *driver = interface->driver;
			if (driver) {
				if (driver->owner)
					__MOD_INC_USE_COUNT(driver->owner);
				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);
				/* we don't need the driver any longer */
				if (driver->owner)
					__MOD_DEC_USE_COUNT(driver->owner);
			}
			/* remove our device node for this interface */
			put_device(&interface->dev);
		}
	}

	/* Free up all the children.. */
	for (i = 0; i < USB_MAXCHILDREN; i++) {
		struct usb_device **child = dev->children + i;
		if (*child)
			usb_disconnect(child);
	}

	/* Let policy agent unload modules etc */
	call_policy ("remove", dev);

	/* Free the device number and remove the /proc/bus/usb entry */
	if (dev->devnum > 0) {
		clear_bit(dev->devnum, dev->bus->devmap.devicemap);
		usbfs_remove_device(dev);
		put_device(&dev->dev);
	}

	/* Decrement the reference count, it'll auto free everything when */
	/* it hits 0 which could very well be now */
	usb_put_dev(dev);
}

/**
 * usb_connect - connects a new device during enumeration (usbcore-internal)
 * @dev: partially enumerated device
 *
 * Connect a new USB device. This basically just initializes
 * the USB device information and sets up the topology - it's
 * up to the low-level driver to reset the port and actually
 * do the setup (the upper levels don't know how to do that).
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 */
void usb_connect(struct usb_device *dev)
{
	int devnum;
	// FIXME needs locking for SMP!!
	/* why? this is called only from the hub thread, 
	 * which hopefully doesn't run on multiple CPU's simultaneously 8-)
	 * ... it's also called from modprobe/rmmod/apmd threads as part
	 * of virtual root hub init/reinit.  In the init case, the hub code 
	 * won't have seen this, but not so for reinit ... 
	 */
	dev->descriptor.bMaxPacketSize0 = 8;  /* Start off at 8 bytes  */
#ifndef DEVNUM_ROUND_ROBIN
	devnum = find_next_zero_bit(dev->bus->devmap.devicemap, 128, 1);
#else	/* round_robin alloc of devnums */
	/* Try to allocate the next devnum beginning at bus->devnum_next. */
	devnum = find_next_zero_bit(dev->bus->devmap.devicemap, 128, dev->bus->devnum_next);
	if (devnum >= 128)
		devnum = find_next_zero_bit(dev->bus->devmap.devicemap, 128, 1);

	dev->bus->devnum_next = ( devnum >= 127 ? 1 : devnum + 1);
#endif	/* round_robin alloc of devnums */

	if (devnum < 128) {
		set_bit(devnum, dev->bus->devmap.devicemap);
		dev->devnum = devnum;
	}
}

/*
 * These are the actual routines to send
 * and receive control messages.
 */

// hub-only!! ... and only exported for reset/reinit path.
// otherwise used internally, for usb_new_device()
int usb_set_address(struct usb_device *dev)
{
	return usb_control_msg(dev, usb_snddefctrl(dev), USB_REQ_SET_ADDRESS,
		// FIXME USB_CTRL_SET_TIMEOUT
		0, dev->devnum, 0, NULL, 0, HZ * USB_CTRL_GET_TIMEOUT);
}

/**
 * usb_get_descriptor - issues a generic GET_DESCRIPTOR request
 * @dev: the device whose descriptor is being retrieved
 * @type: the descriptor type (USB_DT_*)
 * @index: the number of the descriptor
 * @buf: where to put the descriptor
 * @size: how big is "buf"?
 * Context: !in_interrupt ()
 *
 * Gets a USB descriptor.  Convenience functions exist to simplify
 * getting some types of descriptors.  Use
 * usb_get_device_descriptor() for USB_DT_DEVICE,
 * and usb_get_string() or usb_string() for USB_DT_STRING.
 * Configuration descriptors (USB_DT_CONFIG) are part of the device
 * structure, at least for the current configuration.
 * In addition to a number of USB-standard descriptors, some
 * devices also use class-specific or vendor-specific descriptors.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns the number of bytes received on success, or else the status code
 * returned by the underlying usb_control_msg() call.
 */
int usb_get_descriptor(struct usb_device *dev, unsigned char type, unsigned char index, void *buf, int size)
{
	int i = 5;
	int result;
	
	memset(buf,0,size);	// Make sure we parse really received data

	while (i--) {
		/* retries if the returned length was 0; flakey device */
		if ((result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
				    USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
				    (type << 8) + index, 0, buf, size,
				    HZ * USB_CTRL_GET_TIMEOUT)) > 0
				|| result == -EPIPE)
			break;
	}
	return result;
}

/**
 * usb_get_string - gets a string descriptor
 * @dev: the device whose string descriptor is being retrieved
 * @langid: code for language chosen (from string descriptor zero)
 * @index: the number of the descriptor
 * @buf: where to put the string
 * @size: how big is "buf"?
 * Context: !in_interrupt ()
 *
 * Retrieves a string, encoded using UTF-16LE (Unicode, 16 bits per character,
 * in little-endian byte order).
 * The usb_string() function will often be a convenient way to turn
 * these strings into kernel-printable form.
 *
 * Strings may be referenced in device, configuration, interface, or other
 * descriptors, and could also be used in vendor-specific ways.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns the number of bytes received on success, or else the status code
 * returned by the underlying usb_control_msg() call.
 */
int usb_get_string(struct usb_device *dev, unsigned short langid, unsigned char index, void *buf, int size)
{
	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
		USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
		(USB_DT_STRING << 8) + index, langid, buf, size,
		HZ * USB_CTRL_GET_TIMEOUT);
}

/**
 * usb_get_device_descriptor - (re)reads the device descriptor
 * @dev: the device whose device descriptor is being updated
 * Context: !in_interrupt ()
 *
 * Updates the copy of the device descriptor stored in the device structure,
 * which dedicates space for this purpose.  Note that several fields are
 * converted to