usb.c

linux core 函数例程

	add_wait_queue(&awd.wqh, &wait);

	urb->context = &awd;
	status = usb_submit_urb(urb, GFP_KERNEL);
	if (status) {
		// something went wrong
		usb_free_urb(urb);
		set_current_state(TASK_RUNNING);
		remove_wait_queue(&awd.wqh, &wait);
		return status;
	}

	while (timeout && !awd.done)
	{
		timeout = schedule_timeout(timeout);
		set_current_state(TASK_UNINTERRUPTIBLE);
		rmb();
	}

	set_current_state(TASK_RUNNING);
	remove_wait_queue(&awd.wqh, &wait);

	if (!timeout && !awd.done) {
		if (urb->status != -EINPROGRESS) {	/* No callback?!! */
			printk(KERN_ERR "usb: raced timeout, "
			    "pipe 0x%x status %d time left %d\n",
			    urb->pipe, urb->status, timeout);
			status = urb->status;
		} else {
			printk("usb_control/bulk_msg: timeout\n");
			usb_unlink_urb(urb);  // remove urb safely
			status = -ETIMEDOUT;
		}
	} else
		status = urb->status;

	if (actual_length)
		*actual_length = urb->actual_length;

	usb_free_urb(urb);
  	return status;
}

/*-------------------------------------------------------------------*/
// returns status (negative) or length (positive)
int usb_internal_control_msg(struct usb_device *usb_dev, unsigned int pipe, 
			    struct usb_ctrlrequest *cmd,  void *data, int len, int timeout)
{
	struct urb *urb;
	int retv;
	int length;

	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;
  
	FILL_CONTROL_URB(urb, usb_dev, pipe, (unsigned char*)cmd, data, len,
		   usb_api_blocking_completion, 0);

	retv = usb_start_wait_urb(urb, timeout, &length);
	if (retv < 0)
		return retv;
	else
		return length;
}

/**
 *	usb_control_msg - Builds a control urb, sends it off and waits for completion
 *	@dev: pointer to the usb device to send the message to
 *	@pipe: endpoint "pipe" to send the message to
 *	@request: USB message request value
 *	@requesttype: USB message request type value
 *	@value: USB message value
 *	@index: USB message index value
 *	@data: pointer to the data to send
 *	@size: length in bytes of the data to send
 *	@timeout: time in jiffies to wait for the message to complete before
 *		timing out (if 0 the wait is forever)
 *	Context: !in_interrupt ()
 *
 *	This function sends a simple control message to a specified endpoint
 *	and waits for the message to complete, or timeout.
 *	
 *	If successful, it returns the number of bytes transferred, otherwise a negative error number.
 *
 *	Don't use this function from within an interrupt context, like a
 *	bottom half handler.  If you need an asynchronous message, or need to send
 *	a message from within interrupt context, use usb_submit_urb()
 */
int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype,
			 __u16 value, __u16 index, void *data, __u16 size, int timeout)
{
	struct usb_ctrlrequest *dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
	int ret;
	
	if (!dr)
		return -ENOMEM;

	dr->bRequestType= requesttype;
	dr->bRequest = request;
	dr->wValue = cpu_to_le16p(&value);
	dr->wIndex = cpu_to_le16p(&index);
	dr->wLength = cpu_to_le16p(&size);

	//dbg("usb_control_msg");	

	ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);

	kfree(dr);

	return ret;
}


/**
 *	usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion
 *	@usb_dev: pointer to the usb device to send the message to
 *	@pipe: endpoint "pipe" to send the message to
 *	@data: pointer to the data to send
 *	@len: length in bytes of the data to send
 *	@actual_length: pointer to a location to put the actual length transferred in bytes
 *	@timeout: time in jiffies to wait for the message to complete before
 *		timing out (if 0 the wait is forever)
 *	Context: !in_interrupt ()
 *
 *	This function sends a simple bulk message to a specified endpoint
 *	and waits for the message to complete, or timeout.
 *	
 *	If successful, it returns 0, otherwise a negative error number.
 *	The number of actual bytes transferred will be stored in the 
 *	actual_length paramater.
 *
 *	Don't use this function from within an interrupt context, like a
 *	bottom half handler.  If you need an asynchronous message, or need to
 *	send a message from within interrupt context, use usb_submit_urb()
 */
int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe, 
			void *data, int len, int *actual_length, int timeout)
{
	struct urb *urb;

	if (len < 0)
		return -EINVAL;

	urb=usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;

	FILL_BULK_URB(urb, usb_dev, pipe, data, len,
		    usb_api_blocking_completion, 0);

	return usb_start_wait_urb(urb,timeout,actual_length);
}

/**
 * usb_get_current_frame_number - return current bus frame number
 * @dev: the device whose bus is being queried
 *
 * Returns the current frame number for the USB host controller
 * used with the given USB device.  This can be used when scheduling
 * isochronous requests.
 *
 * Note that different kinds of host controller have different
 * "scheduling horizons".  While one type might support scheduling only
 * 32 frames into the future, others could support scheduling up to
 * 1024 frames into the future.
 */
int usb_get_current_frame_number(struct usb_device *dev)
{
	return dev->bus->op->get_frame_number (dev);
}

/*-------------------------------------------------------------------*/

static int usb_parse_endpoint(struct usb_endpoint_descriptor *endpoint, unsigned char *buffer, int size)
{
	struct usb_descriptor_header *header;
	unsigned char *begin;
	int parsed = 0, len, numskipped;

	header = (struct usb_descriptor_header *)buffer;

	/* Everything should be fine being passed into here, but we sanity */
	/*  check JIC */
	if (header->bLength > size) {
		err("ran out of descriptors parsing");
		return -1;
	}
		
	if (header->bDescriptorType != USB_DT_ENDPOINT) {
		warn("unexpected descriptor 0x%X, expecting endpoint descriptor, type 0x%X",
			endpoint->bDescriptorType, USB_DT_ENDPOINT);
		return parsed;
	}

	if (header->bLength == USB_DT_ENDPOINT_AUDIO_SIZE)
		memcpy(endpoint, buffer, USB_DT_ENDPOINT_AUDIO_SIZE);
	else
		memcpy(endpoint, buffer, USB_DT_ENDPOINT_SIZE);
	
	le16_to_cpus(&endpoint->wMaxPacketSize);

	buffer += header->bLength;
	size -= header->bLength;
	parsed += header->bLength;

	/* 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 < 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;
		parsed += 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) {
		endpoint->extra = NULL;
		endpoint->extralen = 0;
		return parsed;
	}

	endpoint->extra = kmalloc(len, GFP_KERNEL);

	if (!endpoint->extra) {
		err("couldn't allocate memory for endpoint extra descriptors");
		endpoint->extralen = 0;
		return parsed;
	}

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

	return parsed;
}

static int usb_parse_interface(struct usb_interface *interface, unsigned char *buffer, int size)
{
	int i, len, numskipped, retval, parsed = 0;
	struct usb_descriptor_header *header;
	struct usb_interface_descriptor *ifp;
	unsigned char *begin;

	interface->act_altsetting = 0;
	interface->num_altsetting = 0;
	interface->max_altsetting = USB_ALTSETTINGALLOC;

	interface->altsetting = kmalloc(sizeof(struct usb_interface_descriptor) * interface->max_altsetting, GFP_KERNEL);
	
	if (!interface->altsetting) {
		err("couldn't kmalloc interface->altsetting");
		return -1;
	}

	while (size > 0) {
		if (interface->num_altsetting >= interface->max_altsetting) {
			void *ptr;
			int oldmas;

			oldmas = interface->max_altsetting;
			interface->max_altsetting += USB_ALTSETTINGALLOC;
			if (interface->max_altsetting > USB_MAXALTSETTING) {
				warn("too many alternate settings (max %d)",
					USB_MAXALTSETTING);
				return -1;
			}

			ptr = interface->altsetting;
			interface->altsetting = kmalloc(sizeof(struct usb_interface_descriptor) * interface->max_altsetting, GFP_KERNEL);
			if (!interface->altsetting) {
				err("couldn't kmalloc interface->altsetting");
				interface->altsetting = ptr;
				return -1;
			}
			memcpy(interface->altsetting, ptr, sizeof(struct usb_interface_descriptor) * oldmas);

			kfree(ptr);
		}

		ifp = interface->altsetting + interface->num_altsetting;
		ifp->endpoint = NULL;
		ifp->extra = NULL;
		ifp->extralen = 0;
		interface->num_altsetting++;

		memcpy(ifp, buffer, USB_DT_INTERFACE_SIZE);

		/* Skip over the interface */
		buffer += ifp->bLength;
		parsed += ifp->bLength;
		size -= ifp->bLength;

		begin = buffer;
		numskipped = 0;

		/* Skip over any interface, class or vendor descriptors */
		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 we find another "proper" descriptor then we're done  */
			if ((header->bDescriptorType == USB_DT_INTERFACE) ||
			    (header->bDescriptorType == USB_DT_ENDPOINT) ||
			    (header->bDescriptorType == USB_DT_CONFIG) ||
			    (header->bDescriptorType == USB_DT_DEVICE))
				break;

			numskipped++;

			buffer += header->bLength;
			parsed += header->bLength;
			size -= header->bLength;
		}

		if (numskipped)
			dbg("skipped %d class/vendor specific interface descriptors", numskipped);

		/* Copy any unknown descriptors into a storage area for */
		/*  drivers to later parse */
		len = (int)(buffer - begin);
		if (len) {
			ifp->extra = kmalloc(len, GFP_KERNEL);

			if (!ifp->extra) {
				err("couldn't allocate memory for interface extra descriptors");
				ifp->extralen = 0;
				return -1;
			}
			memcpy(ifp->extra, begin, len);
			ifp->extralen = len;
		}

		/* Did we hit an unexpected descriptor? */
		header = (struct usb_descriptor_header *)buffer;
		if ((size >= sizeof(struct usb_descriptor_header)) &&
		    ((header->bDescriptorType == USB_DT_CONFIG) ||
		     (header->bDescriptorType == USB_DT_DEVICE)))
			return parsed;

		if (ifp->bNumEndpoints > USB_MAXENDPOINTS) {
			warn("too many endpoints");
			return -1;
		}

		ifp->endpoint = (struct usb_endpoint_descriptor *)
			kmalloc(ifp->bNumEndpoints *
			sizeof(struct usb_endpoint_descriptor), GFP_KERNEL);
		if (!ifp->endpoint) {
			err("out of memory");
			return -1;	
		}

		memset(ifp->endpoint, 0, ifp->bNumEndpoints *
			sizeof(struct usb_endpoint_descriptor));
	
		for (i = 0; i < ifp->bNumEndpoints; i++) {
			header = (struct usb_descriptor_header *)buffer;

			if (header->bLength > size) {
				err("ran out of descriptors parsing");
				return -1;
			}
		
			retval = usb_parse_endpoint(ifp->endpoint + i, buffer, size);
			if (retval < 0)
				return retval;

			buffer += retval;
			parsed += retval;
			size -= retval;
		}

		/* We check to see if it's an alternate to this one */
		ifp = (struct usb_interface_descriptor *)buffer;
		if (size < USB_DT_INTERFACE_SIZE ||
		    ifp->bDescriptorType != USB_DT_INTERFACE ||
		    !ifp->bAlternateSetting)
			return parsed;
	}

	return parsed;
}

int usb_parse_configuration(struct usb_config_descriptor *config, char *buffer)
{
	int i, retval, size;
	struct usb_descriptor_header *header;

	memcpy(config, buffer, USB_DT_CONFIG_SIZE);
	le16_to_cpus(&config->wTotalLength);
	size = config->wTotalLength;