usb.c

是关于linux2.5.1的完全源码

		/* MUST go to zero here, else someone's hanging on to
		 * a device that's supposed to have been cleaned up!!
		 */
		BUG ();
	}

	dev->bus->op->deallocate (dev);
	usb_destroy_configuration (dev);
	usb_bus_put (dev->bus);
	kfree (dev);
}

/**
 * usb_alloc_urb - creates a new urb for a USB driver to use
 * @iso_packets: number of iso packets for this urb
 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
 *	valid options for this.
 *
 * Creates an urb for the USB driver to use, initializes a few internal
 * structures, incrementes the usage counter, and returns a pointer to it.
 *
 * If no memory is available, NULL is returned.
 *
 * If the driver want to use this urb for interrupt, control, or bulk
 * endpoints, pass '0' as the number of iso packets.
 *
 * The driver must call usb_free_urb() when it is finished with the urb.
 */
struct urb *usb_alloc_urb(int iso_packets, int mem_flags)
{
	struct urb *urb;

	urb = (struct urb *)kmalloc(sizeof(struct urb) + 
		iso_packets * sizeof(struct usb_iso_packet_descriptor),
		mem_flags);
	if (!urb) {
		err("alloc_urb: kmalloc failed");
		return NULL;
	}

	memset(urb, 0, sizeof(*urb));
	urb->count = (atomic_t)ATOMIC_INIT(1);
	spin_lock_init(&urb->lock);

	return urb;
}

/**
 * usb_free_urb - frees the memory used by a urb when all users of it are finished
 * @urb: pointer to the urb to free
 *
 * Must be called when a user of a urb is finished with it.  When the last user
 * of the urb calls this function, the memory of the urb is freed.
 *
 * Note: The transfer buffer associated with the urb is not freed, that must be
 * done elsewhere.
 */
void usb_free_urb(struct urb *urb)
{
	if (urb)
		if (atomic_dec_and_test(&urb->count))
			kfree(urb);
}

/**
 * usb_get_urb - incrementes the reference count of the urb
 * @urb: pointer to the urb to modify
 *
 * This must be  called whenever a urb is transfered from a device driver to a
 * host controller driver.  This allows proper reference counting to happen
 * for urbs.
 *
 * A pointer to the urb with the incremented reference counter is returned.
 */
struct urb * usb_get_urb(struct urb *urb)
{
	if (urb) {
		atomic_inc(&urb->count);
		return urb;
	} else
		return NULL;
}
		
		
/*-------------------------------------------------------------------*/

/**
 * usb_submit_urb - asynchronously issue a transfer request for an endpoint
 * @urb: pointer to the urb describing the request
 * @mem_flags: the type of memory to allocate, see kmalloc() for a list
 *	of valid options for this.
 *
 * This submits a transfer request, and transfers control of the URB
 * describing that request to the USB subsystem.  Request completion will
 * indicated later, asynchronously, by calling the completion handler.
 * This call may be issued in interrupt context.
 *
 * The caller must have correctly initialized the URB before submitting
 * it.  Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
 * available to ensure that most fields are correctly initialized, for
 * the particular kind of transfer, although they will not initialize
 * any transfer flags.
 *
 * Successful submissions return 0; otherwise this routine returns a
 * negative error number.  If the submission is successful, the complete
 * fuction of the urb will be called when the USB host driver is
 * finished with the urb (either a successful transmission, or some
 * error case.)
 *
 * Unreserved Bandwidth Transfers:
 *
 * Bulk or control requests complete only once.  When the completion
 * function is called, control of the URB is returned to the device
 * driver which issued the request.  The completion handler may then
 * immediately free or reuse that URB.
 *
 * Bulk URBs will be queued if the USB_QUEUE_BULK transfer flag is set
 * in the URB.  This can be used to maximize bandwidth utilization by
 * letting the USB controller start work on the next URB without any
 * delay to report completion (scheduling and processing an interrupt)
 * and then submit that next request.
 *
 * For control endpoints, the synchronous usb_control_msg() call is
 * often used (in non-interrupt context) instead of this call.
 *
 * Reserved Bandwidth Transfers:
 *
 * Periodic URBs (interrupt or isochronous) are completed repeatedly,
 * until the original request is aborted.  When the completion callback
 * indicates the URB has been unlinked (with a special status code),
 * control of that URB returns to the device driver.  Otherwise, the
 * completion handler does not control the URB, and should not change
 * any of its fields.
 *
 * Note that isochronous URBs should be submitted in a "ring" data
 * structure (using urb->next) to ensure that they are resubmitted
 * appropriately.
 *
 * If the USB subsystem can't reserve sufficient bandwidth to perform
 * the periodic request, and bandwidth reservation is being done for
 * this controller, submitting such a periodic request will fail.
 *
 * Memory Flags:
 *
 * General rules for how to decide which mem_flags to use:
 * 
 * Basically the rules are the same as for kmalloc.  There are four
 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
 * GFP_ATOMIC.
 *
 * GFP_NOFS is not ever used, as it has not been implemented yet.
 *
 * There are three situations you must use GFP_ATOMIC.
 *    a) you are inside a completion handler, an interrupt, bottom half,
 *       tasklet or timer.
 *    b) you are holding a spinlock or rwlock (does not apply to
 *       semaphores)
 *    c) current->state != TASK_RUNNING, this is the case only after
 *       you've changed it.
 * 
 * GFP_NOIO is used in the block io path and error handling of storage
 * devices.
 *
 * All other situations use GFP_KERNEL.
 *
 * Specfic rules for how to decide which mem_flags to use:
 *
 *    - start_xmit, timeout, and receive methods of network drivers must
 *      use GFP_ATOMIC (spinlock)
 *    - queuecommand methods of scsi drivers must use GFP_ATOMIC (spinlock)
 *    - If you use a kernel thread with a network driver you must use
 *      GFP_NOIO, unless b) or c) apply
 *    - After you have done a down() you use GFP_KERNEL, unless b) or c)
 *      apply or your are in a storage driver's block io path
 *    - probe and disconnect use GFP_KERNEL unless b) or c) apply
 *    - Changing firmware on a running storage or net device uses
 *      GFP_NOIO, unless b) or c) apply
 *
 */
int usb_submit_urb(struct urb *urb, int mem_flags)
{
	if (urb && urb->dev && urb->dev->bus && urb->dev->bus->op)
		return urb->dev->bus->op->submit_urb(urb, mem_flags);
	else
		return -ENODEV;
}

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

/**
 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
 * @urb: pointer to urb describing a previously submitted request
 *
 * This routine cancels an in-progress request.  The requests's
 * completion handler will be called with a status code indicating
 * that the request has been canceled, and that control of the URB
 * has been returned to that device driver.  This is the only way
 * to stop an interrupt transfer, so long as the device is connected.
 *
 * When the USB_ASYNC_UNLINK transfer flag for the URB is clear, this
 * request is synchronous.  Success is indicated by returning zero,
 * at which time the urb will have been unlinked,
 * and the completion function will see status -ENOENT.  Failure is
 * indicated by any other return value.  This mode may not be used
 * when unlinking an urb from an interrupt context, such as a bottom
 * half or a completion handler,
 *
 * When the USB_ASYNC_UNLINK transfer flag for the URB is set, this
 * request is asynchronous.  Success is indicated by returning -EINPROGRESS,
 * at which time the urb will normally not have been unlinked,
 * and the completion function will see status -ECONNRESET.  Failure is
 * indicated by any other return value.
 */
int usb_unlink_urb(struct urb *urb)
{
	if (urb && urb->dev && urb->dev->bus && urb->dev->bus->op)
		return urb->dev->bus->op->unlink_urb(urb);
	else
		return -ENODEV;
}
/*-------------------------------------------------------------------*
 *                         SYNCHRONOUS CALLS                         *
 *-------------------------------------------------------------------*/

struct usb_api_data {
	wait_queue_head_t wqh;
	int done;
};

static void usb_api_blocking_completion(struct urb *urb)
{
	struct usb_api_data *awd = (struct usb_api_data *)urb->context;

	awd->done = 1;
	wmb();
	wake_up(&awd->wqh);
}

// Starts urb and waits for completion or timeout
static int usb_start_wait_urb(struct urb *urb, int timeout, int* actual_length)
{ 
	DECLARE_WAITQUEUE(wait, current);
	struct usb_api_data awd;
	int status;

	init_waitqueue_head(&awd.wqh); 	
	awd.done = 0;

	set_current_state(TASK_UNINTERRUPTIBLE);
	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;