irda-usb.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

	 * a continuous stream of data but separate packets.
	 * In this case, the USB layer will insert an empty USB frame (TD)
	 * after each of our packets that is exact multiple of the frame size.
	 * This is how the dongle will detect the end of packet - Jean II */
	purb->transfer_flags |= USB_ZERO_PACKET;
	/* Timeout need to be shorter than NET watchdog timer */
	purb->timeout = MSECS_TO_JIFFIES(200);

	/* Generate min turn time. FIXME: can we do better than this? */
	/* Trying to a turnaround time at this level is trying to measure
	 * processor clock cycle with a wrist-watch, approximate at best...
	 *
	 * What we know is the last time we received a frame over USB.
	 * Due to latency over USB that depend on the USB load, we don't
	 * know when this frame was received over IrDA (a few ms before ?)
	 * Then, same story for our outgoing frame...
	 *
	 * In theory, the USB dongle is supposed to handle the turnaround
	 * by itself (spec 1.0, chater 4, page 6). Who knows ??? That's
	 * why this code is enabled only for dongles that doesn't meet
	 * the spec.
	 * Jean II */
	if (self->capability & IUC_NO_TURN) {
		mtt = irda_get_mtt(skb);
		if (mtt) {
			int diff;
			do_gettimeofday(&self->now);
			diff = self->now.tv_usec - self->stamp.tv_usec;
#ifdef IU_USB_MIN_RTT
			/* Factor in USB delays -> Get rid of udelay() that
			 * would be lost in the noise - Jean II */
			diff += IU_USB_MIN_RTT;
#endif /* IU_USB_MIN_RTT */
			if (diff < 0)
				diff += 1000000;

		        /* Check if the mtt is larger than the time we have
			 * already used by all the protocol processing
			 */
			if (mtt > diff) {
				mtt -= diff;
				if (mtt > 1000)
					mdelay(mtt/1000);
				else
					udelay(mtt);
			}
		}
	}
	
	/* Ask USB to send the packet */
	if ((res = usb_submit_urb(purb))) {
		WARNING("%s(), failed Tx URB\n", __FUNCTION__);
		self->stats.tx_errors++;
		/* Let USB recover : We will catch that in the watchdog */
		/*netif_start_queue(netdev);*/
	} else {
		/* Increment packet stats */
		self->stats.tx_packets++;
                self->stats.tx_bytes += skb->len;
		
		netdev->trans_start = jiffies;
	}
	spin_unlock_irqrestore(&self->lock, flags);
	
	return 0;

drop:
	/* Drop silently the skb and exit */
	dev_kfree_skb(skb);
	spin_unlock_irqrestore(&self->lock, flags);
	return 0;
}

/*------------------------------------------------------------------*/
/*
 * Note : this function will be called only for tx_urb...
 */
static void write_bulk_callback(struct urb *purb)
{
	unsigned long flags;
	struct sk_buff *skb = purb->context;
	struct irda_usb_cb *self = ((struct irda_skb_cb *) skb->cb)->context;
	
	IRDA_DEBUG(2, "%s()\n", __FUNCTION__);

	/* We should always have a context */
	if (self == NULL) {
		WARNING("%s(), Bug : self == NULL\n", __FUNCTION__);
		return;
	}

	/* Free up the skb */
	dev_kfree_skb_any(skb);
	purb->context = NULL;

	/* Check for timeout and other USB nasties */
	if(purb->status != USB_ST_NOERROR) {
		/* I get a lot of -ECONNABORTED = -103 here - Jean II */
		IRDA_DEBUG(0, "%s(), URB complete status %d, transfer_flags 0x%04X\n", __FUNCTION__, purb->status, purb->transfer_flags);

		/* Don't do anything here, that might confuse the USB layer,
		 * and we could go in recursion and blow the kernel stack...
		 * Instead, we will wait for irda_usb_net_timeout(), the
		 * network layer watchdog, to fix the situation.
		 * Jean II */
		/* A reset of the dongle might be welcomed here - Jean II */
		return;
	}

	/* urb is now available */
	//purb->status = USB_ST_NOERROR; -> tested above

	/* Make sure we read self->present properly */
	spin_lock_irqsave(&self->lock, flags);

	/* If the network is closed, stop everything */
	if ((!self->netopen) || (!self->present)) {
		IRDA_DEBUG(0, "%s(), Network is gone...\n", __FUNCTION__);
		spin_unlock_irqrestore(&self->lock, flags);
		return;
	}

	/* If we need to change the speed or xbofs, do it now */
	if ((self->new_speed != -1) || (self->new_xbofs != -1)) {
		IRDA_DEBUG(1, "%s(), Changing speed now...\n", __FUNCTION__);
		irda_usb_change_speed_xbofs(self);
	} else {
		/* Otherwise, allow the stack to send more packets */
		netif_wake_queue(self->netdev);
	}
	spin_unlock_irqrestore(&self->lock, flags);
}

/*------------------------------------------------------------------*/
/*
 * Watchdog timer from the network layer.
 * After a predetermined timeout, if we don't give confirmation that
 * the packet has been sent (i.e. no call to netif_wake_queue()),
 * the network layer will call this function.
 * Note that URB that we submit have also a timeout. When the URB timeout
 * expire, the normal URB callback is called (write_bulk_callback()).
 */
static void irda_usb_net_timeout(struct net_device *netdev)
{
	unsigned long flags;
	struct irda_usb_cb *self = netdev->priv;
	struct urb *purb;
	int	done = 0;	/* If we have made any progress */

	IRDA_DEBUG(0, "%s(), Network layer thinks we timed out!\n", __FUNCTION__);

	/* Protect us from USB callbacks, net Tx and else. */
	spin_lock_irqsave(&self->lock, flags);

	if ((!self) || (!self->present)) {
		WARNING("%s(), device not present!\n", __FUNCTION__);
		netif_stop_queue(netdev);
		spin_unlock_irqrestore(&self->lock, flags);
		return;
	}

	/* Check speed URB */
	purb = &(self->speed_urb);
	if (purb->status != USB_ST_NOERROR) {
		IRDA_DEBUG(0, "%s: Speed change timed out, urb->status=%d, urb->transfer_flags=0x%04X\n", netdev->name, purb->status, purb->transfer_flags);

		switch (purb->status) {
		case USB_ST_URB_PENDING:	/* -EINPROGRESS == -115 */
			usb_unlink_urb(purb);
			/* Note : above will  *NOT* call netif_wake_queue()
			 * in completion handler, we will come back here.
			 * Jean II */
			done = 1;
			break;
		case -ECONNABORTED:		/* -103 */
		case -ECONNRESET:		/* -104 */
		case -ETIMEDOUT:		/* -110 */
		case -ENOENT:			/* -2 (urb unlinked by us)  */
		default:			/* ??? - Play safe */
			purb->status = USB_ST_NOERROR;
			netif_wake_queue(self->netdev);
			done = 1;
			break;
		}
	}

	/* Check Tx URB */
	purb = &(self->tx_urb);
	if (purb->status != USB_ST_NOERROR) {
		struct sk_buff *skb = purb->context;

		IRDA_DEBUG(0, "%s: Tx timed out, urb->status=%d, urb->transfer_flags=0x%04X\n", netdev->name, purb->status, purb->transfer_flags);

		/* Increase error count */
		self->stats.tx_errors++;

#ifdef IU_BUG_KICK_TIMEOUT
		/* Can't be a bad idea to reset the speed ;-) - Jean II */
		if(self->new_speed == -1)
			self->new_speed = self->speed;
		if(self->new_xbofs == -1)
			self->new_xbofs = self->xbofs;
		irda_usb_change_speed_xbofs(self);
#endif /* IU_BUG_KICK_TIMEOUT */

		switch (purb->status) {
		case USB_ST_URB_PENDING:	/* -EINPROGRESS == -115 */
			usb_unlink_urb(purb);
			/* Note : above will  *NOT* call netif_wake_queue()
			 * in completion handler, because purb->status will
			 * be -ENOENT. We will fix that at the next watchdog,
			 * leaving more time to USB to recover...
			 * Also, we are in interrupt, so we need to have
			 * USB_ASYNC_UNLINK to work properly...
			 * Jean II */
			done = 1;
			break;
		case -ECONNABORTED:		/* -103 */
		case -ECONNRESET:		/* -104 */
		case -ETIMEDOUT:		/* -110 */
		case -ENOENT:			/* -2 (urb unlinked by us)  */
		default:			/* ??? - Play safe */
			if(skb != NULL) {
				dev_kfree_skb_any(skb);
				purb->context = NULL;
			}
			purb->status = USB_ST_NOERROR;
			netif_wake_queue(self->netdev);
			done = 1;
			break;
		}
	}
	spin_unlock_irqrestore(&self->lock, flags);

	/* Maybe we need a reset */
	/* Note : Some drivers seem to use a usb_set_interface() when they
	 * need to reset the hardware. Hum...
	 */

	/* if(done == 0) */
}

/************************* RECEIVE ROUTINES *************************/
/*
 * Receive packets from the USB layer stack and pass them to the IrDA stack.
 * Try to work around USB failures...
 */

/*
 * Note :
 * Some of you may have noticed that most dongle have an interrupt in pipe
 * that we don't use. Here is the little secret...
 * When we hang a Rx URB on the bulk in pipe, it generates some USB traffic
 * in every USB frame. This is unnecessary overhead.
 * The interrupt in pipe will generate an event every time a packet is
 * received. Reading an interrupt pipe adds minimal overhead, but has some
 * latency (~1ms).
 * If we are connected (speed != 9600), we want to minimise latency, so
 * we just always hang the Rx URB and ignore the interrupt.
 * If we are not connected (speed == 9600), there is usually no Rx traffic,
 * and we want to minimise the USB overhead. In this case we should wait
 * on the interrupt pipe and hang the Rx URB only when an interrupt is
 * received.
 * Jean II
 */

/*------------------------------------------------------------------*/
/*
 * Submit a Rx URB to the USB layer to handle reception of a frame
 *
 * Important note :
 * The function process_urb() in usb-uhci.c contains the following code :
 * >	urb->complete ((struct urb *) urb);
 * >	// Re-submit the URB if ring-linked
 * >	if (is_ring && (urb->status != -ENOENT) && !contains_killed) {
 * >		urb->dev=usb_dev;
 * >		uhci_submit_urb (urb);
 * >	}
 * The way I see it is that if we submit more than one Rx URB at a
 * time, the Rx URB can be automatically re-submitted after the
 * completion handler is called.
 * We make sure to disable this feature by setting urb->next to NULL
 *
 * My take is that it's a questionable feature, and quite difficult
 * to control and to make work effectively.
 * The outcome (re-submited or not) depend on various complex
 * test ('is_ring' and 'contains_killed'), and the completion handler
 * don't have this information, so basically the driver has no way
 * to know if URB are resubmitted or not. Yuck !
 * If everything is perfect, it's cool, but the problem is when
 * an URB is killed (timeout, call to unlink_urb(), ...), things get
 * messy...
 * The other problem is that this scheme deal only with the URB
 * and ignore everything about the associated buffer. So, it would
 * resubmit URB even if the buffer is still in use or non-existent.
 * On the other hand, submitting ourself in the completion callback
 * is quite trivial and work well (this function).
 * Moreover, this scheme doesn't allow to have an idle URB, which is
 * necessary to overcome some URB failures.
 *
 * Jean II
 */
static void irda_usb_submit(struct irda_usb_cb *self, struct sk_buff *skb, struct urb *purb)
{
	struct irda_skb_cb *cb;
	int ret;

	IRDA_DEBUG(2, "%s()\n", __FUNCTION__);

	/* Check that we have an urb */
	if (!purb) {
		WARNING("%s(), Bug : purb == NULL\n", __FUNCTION__);
		return;
	}

	/* Allocate new skb if it has not been recycled */
	if (!skb) {
		skb = dev_alloc_skb(IRDA_USB_MAX_MTU + 1);
		if (!skb) {
			/* If this ever happen, we are in deep s***.
			 * Basically, the Rx path will stop... */
			WARNING("%s(), Failed to allocate Rx skb\n", __FUNCTION__);
			return;
		}
	} else  {
		/* Reset recycled skb */
		skb->data = skb->tail = skb->head;
		skb->len = 0;
	}
	/* Make sure IP header get aligned (IrDA header is 5 bytes ) */
	skb_reserve(skb, 1);

	/* Save ourselves */
	cb = (struct irda_skb_cb *) skb->cb;
	cb->context = self;

	/* Reinitialize URB */
	FILL_BULK_URB(purb, self->usbdev, 
		      usb_rcvbulkpipe(self->usbdev, self->bulk_in_ep), 
		      skb->data, skb->truesize,
                      irda_usb_receive, skb);
	purb->transfer_flags = USB_QUEUE_BULK;
	/* Note : unlink *must* be synchronous because of the code in 
	 * irda_usb_net_close() -> free the skb - Jean II */
	purb->status = USB_ST_NOERROR;
	purb->next = NULL;	/* Don't auto resubmit URBs */
	
	ret = usb_submit_urb(purb);
	if (ret) {
		/* If this ever happen, we are in deep s***.
		 * Basically, the Rx path will stop... */
		WARNING("%s(), Failed to submit Rx URB %d\n", __FUNCTION__, ret);
	}
}

/*------------------------------------------------------------------*/
/*
 * Function irda_usb_receive(purb)
 *
 *     Called by the USB subsystem when a frame has been received
 *
 */
static void irda_usb_receive(struct urb *purb) 
{
	struct sk_buff *skb = (struct sk_buff *) purb->context;
	struct irda_usb_cb *self; 
	struct irda_skb_cb *cb;
	struct sk_buff *new;
	
	IRDA_DEBUG(2, "%s(), len=%d\n", __FUNCTION__, purb->actual_length);
	
	/* Find ourselves */
	cb = (struct irda_skb_cb *) skb->cb;
	ASSERT(cb != NULL, return;);
	self = (struct irda_usb_cb *) cb->context;
	ASSERT(self != NULL, return;);

	/* If the network is closed or the device gone, stop everything */
	if ((!self->netopen) || (!self->present)) {
		IRDA_DEBUG(0, "%s(), Network is gone!\n", __FUNCTION__);
		/* Don't re-submit the URB : will stall the Rx path */
		return;
	}
	
	/* Check the status */
	if(purb->status != USB_ST_NOERROR) {
		switch (purb->status) {
		case USB_ST_CRC:		/* -EILSEQ */
			self->stats.rx_errors++;
			self->stats.rx_crc_errors++;	
			break;
		case -ECONNRESET:		/* -104 */
			IRDA_DEBUG(0, "%s(), Connection Reset (-104), transfer_flags 0x%04X \n", __FUNCTION__, purb->transfer_flags);
			/* uhci_cleanup_unlink() is going to kill the Rx
			 * URB just after we return. No problem, at this
			 * point the URB will be idle ;-) - Jean II */
			break;
		default:
			IRDA_DEBUG(0, "%s(), RX status %d,transfer_flags 0x%04X \n", __FUNCTION__, purb->status, purb->transfer_flags);
			break;
		}
		goto done;
	}
	
	/* Check for empty frames */
	if (purb->actual_length <= USB_IRDA_HEADER) {
		WARNING("%s(), empty frame!\n", __FUNCTION__);
		goto done;
	}