irda-usb.c

《linux驱动程序设计从入门到精通》一书中所有的程序代码含驱动和相应的应用程序

	/* 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 the usec counter did wraparound, the diff will
			 * go negative (tv_usec is a long), so we need to
			 * correct it by one second. Jean II */
			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 - Irq disabled -> GFP_ATOMIC */
	if ((res = usb_submit_urb(urb, GFP_ATOMIC))) {
		IRDA_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 err;		/* Usually 1 */
}

/*------------------------------------------------------------------*/
/*
 * Note : this function will be called only for tx_urb...
 */
static void write_bulk_callback(struct urb *urb)
{
	unsigned long flags;
	struct sk_buff *skb = urb->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 */
	IRDA_ASSERT(self != NULL, return;);
	/* We should always be called for the speed URB */
	IRDA_ASSERT(urb == self->tx_urb, return;);

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

	/* Check for timeout and other USB nasties */
	if (urb->status != 0) {
		/* I get a lot of -ECONNABORTED = -103 here - Jean II */
		IRDA_DEBUG(0, "%s(), URB complete status %d, transfer_flags 0x%04X\n", __FUNCTION__, urb->status, urb->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 */
	//urb->status = 0; -> 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 changes to speed or xbofs is pending... */
	if ((self->new_speed != -1) || (self->new_xbofs != -1)) {
		if ((self->new_speed != self->speed) ||
		    (self->new_xbofs != self->xbofs)) {
			/* We haven't changed speed yet (because of
			 * IUC_SPEED_BUG), so do it now - Jean II */
			IRDA_DEBUG(1, "%s(), Changing speed now...\n", __FUNCTION__);
			irda_usb_change_speed_xbofs(self);
		} else {
			/* New speed and xbof is now commited in hardware */
			self->new_speed = -1;
			self->new_xbofs = -1;
			/* Done, waiting for next packet */
			netif_wake_queue(self->netdev);
		}
	} 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 *urb;
	int	done = 0;	/* If we have made any progress */

	IRDA_DEBUG(0, "%s(), Network layer thinks we timed out!\n", __FUNCTION__);
	IRDA_ASSERT(self != NULL, return;);

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

	/* self->present *MUST* be read under spinlock */
	if (!self->present) {
		IRDA_WARNING("%s(), device not present!\n", __FUNCTION__);
		netif_stop_queue(netdev);
		spin_unlock_irqrestore(&self->lock, flags);
		return;
	}

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

		switch (urb->status) {
		case -EINPROGRESS:
			usb_unlink_urb(urb);
			/* Note : above will  *NOT* call netif_wake_queue()
			 * in completion handler, we will come back here.
			 * Jean II */
			done = 1;
			break;
		case -ECONNRESET:
		case -ENOENT:			/* urb unlinked by us */
		default:			/* ??? - Play safe */
			urb->status = 0;
			netif_wake_queue(self->netdev);
			done = 1;
			break;
		}
	}

	/* Check Tx URB */
	urb = self->tx_urb;
	if (urb->status != 0) {
		struct sk_buff *skb = urb->context;

		IRDA_DEBUG(0, "%s: Tx timed out, urb->status=%d, urb->transfer_flags=0x%04X\n", netdev->name, urb->status, urb->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 (urb->status) {
		case -EINPROGRESS:
			usb_unlink_urb(urb);
			/* Note : above will  *NOT* call netif_wake_queue()
			 * in completion handler, because urb->status will
			 * be -ENOENT. We will fix that at the next watchdog,
			 * leaving more time to USB to recover...
			 * Jean II */
			done = 1;
			break;
		case -ECONNRESET:
		case -ENOENT:			/* urb unlinked by us */
		default:			/* ??? - Play safe */
			if(skb != NULL) {
				dev_kfree_skb_any(skb);
				urb->context = NULL;
			}
			urb->status = 0;
			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
 *
 * Note : don't read the above as what we are currently doing, but as
 * something we could do with KC dongle. Also don't forget that the
 * interrupt pipe is not part of the original standard, so this would
 * need to be optional...
 * Jean II
 */

/*------------------------------------------------------------------*/
/*
 * Submit a Rx URB to the USB layer to handle reception of a frame
 * Mostly called by the completion callback of the previous URB.
 *
 * Jean II
 */
static void irda_usb_submit(struct irda_usb_cb *self, struct sk_buff *skb, struct urb *urb)
{
	struct irda_skb_cb *cb;
	int ret;

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

	/* This should never happen */
	IRDA_ASSERT(skb != NULL, return;);
	IRDA_ASSERT(urb != NULL, return;);

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

	/* Reinitialize URB */
	usb_fill_bulk_urb(urb, self->usbdev, 
		      usb_rcvbulkpipe(self->usbdev, self->bulk_in_ep), 
		      skb->data, IRDA_SKB_MAX_MTU,
                      irda_usb_receive, skb);
	urb->status = 0;

	/* Can be called from irda_usb_receive (irq handler) -> GFP_ATOMIC */
	ret = usb_submit_urb(urb, GFP_ATOMIC);
	if (ret) {
		/* If this ever happen, we are in deep s***.
		 * Basically, the Rx path will stop... */
		IRDA_WARNING("%s(), Failed to submit Rx URB %d\n",
			     __FUNCTION__, ret);
	}
}

/*------------------------------------------------------------------*/
/*
 * Function irda_usb_receive(urb)
 *
 *     Called by the USB subsystem when a frame has been received
 *
 */
static void irda_usb_receive(struct urb *urb)
{
	struct sk_buff *skb = (struct sk_buff *) urb->context;
	struct irda_usb_cb *self; 
	struct irda_skb_cb *cb;
	struct sk_buff *newskb;
	struct sk_buff *dataskb;
	struct urb *next_urb;
	unsigned int len, docopy;

	IRDA_DEBUG(2, "%s(), len=%d\n", __FUNCTION__, urb->actual_length);
	
	/* Find ourselves */
	cb = (struct irda_skb_cb *) skb->cb;
	IRDA_ASSERT(cb != NULL, return;);
	self = (struct irda_usb_cb *) cb->context;
	IRDA_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 (urb->status != 0) {
		switch (urb->status) {
		case -EILSEQ:
			self->stats.rx_crc_errors++;	
			/* Also precursor to a hot-unplug on UHCI. */
			/* Fallthrough... */
		case -ECONNRESET:
			/* Random error, if I remember correctly */
			/* 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 */
		case -ESHUTDOWN:
			/* That's usually a hot-unplug. Submit will fail... */
		case -ETIME:
			/* Usually precursor to a hot-unplug on OHCI. */
		default:
			self->stats.rx_errors++;
			IRDA_DEBUG(0, "%s(), RX status %d, transfer_flags 0x%04X \n", __FUNCTION__, urb->status, urb->transfer_flags);
			break;
		}
		/* If we received an error, we don't want to resubmit the
		 * Rx URB straight away but to give the USB layer a little
		 * bit of breathing room.
		 * We are in the USB thread context, therefore there is a
		 * danger of recursion (new URB we submit fails, we come
		 * back here).
		 * With recent USB stack (2.6.15+), I'm seeing that on
		 * hot unplug of the dongle...
		 * Lowest effective timer is 10ms...
		 * Jean II */
		self->rx_defer_timer.function = &irda_usb_rx_defer_expired;
		self->rx_defer_timer.data = (unsigned long) urb;
		mod_timer(&self->rx_defer_timer, jiffies + (10 * HZ / 1000));
		return;
	}
	
	/* Check for empty frames */
	if (urb->actual_length <= self->header_length) {
		IRDA_WARNING("%s(), empty frame!\n", __FUNCTION__);
		goto done;
	}

	/*  
	 * Remember the time we received this frame, so we can
	 * reduce the min turn time a bit since we will know
	 * how much time we have used for protocol processing
	 */
        do_gettimeofday(&self->stamp);

	/* Check if we need to copy the data to a new skb or not.
	 * For most frames, we use ZeroCopy and pass the already
	 * allocated skb up the stack.
	 * If the frame is small, it is more efficient to copy it
	 * to save memory (copy will be fast anyway - that's
	 * called Rx-copy-break). Jean II */
	docopy = (urb->actual_length < IRDA_RX_COPY_THRESHOLD);

	/* Allocate a new skb */
	if (self->capability & IUC_STIR421X)
		newskb = dev_alloc_skb(docopy ? urb->actual_length :
				       IRDA_SKB_MAX_MTU +
				       USB_IRDA_STIR421X_HEADER);
	else
		newskb = dev_alloc_skb(docopy ? urb->actual_length :
				       IRDA_SKB_MAX_MTU);

	if (!newskb)  {
		self->stats.rx_dropped++;
		/* We could deliver the current skb, but this would stall
		 * the Rx path. Better drop the packet... Jean II */
		goto done;  
	}

	/* Make sure IP header get aligned (IrDA header is 5 bytes) */
	/* But IrDA-USB header is 1 byte. Jean II */
	//skb_reserve(newskb, USB_IRDA_HEADER - 1);

	if(docopy) {
		/* Copy packet, so we can recycle the original */
		memcpy(newskb->data, skb->data, urb->actual_length);
		/* Deliver this new skb */
		dataskb = newskb;
		/* And hook the old skb to the URB
		 * Note : we don't need to "clean up" the old skb,
		 * as we never touched it. Jean II */
	} else {
		/* We are using ZeroCopy. Deliver old skb */
		dataskb = skb;
		/* And hook the new skb to the URB */
		skb = newskb;
	}

	/* Set proper length on skb & remove USB-IrDA header */
	skb_put(dataskb, urb->actual_length);
	skb_pull(dataskb, self->header_length);

	/* Ask the networking layer to queue the packet for the IrDA stack */
	dataskb->dev = self->netdev;
	dataskb->mac.raw  = dataskb->data;
	dataskb->protocol = htons(ETH_P_IRDA);
	len = dataskb->len;
	netif_rx(dataskb);

	/* Keep stats up to date */
	self->stats.rx_bytes += len;
	self->stats.rx_packets++;
	self->netdev->last_rx = jiffies;

done:
	/* Note : at this point, the URB we've just received (urb)
	 * is still referenced by the USB layer. For example, if we
	 * have received a -ECONNRESET, uhci_cleanup_unlink() will
	 * continue to process it (in fact, cleaning it up).
	 * If we were to submit this URB, disaster would ensue.
	 * Therefore, we submit our idle URB, and put this URB in our
	 * idle slot....
	 * Jean II */
	/* Note : with this scheme, we could submit the idle URB before
	 * processing the Rx URB. I don't think it would buy us anything as
	 * we are running in the USB thread context. Jean II */
	next_urb = self->idle_rx_urb;

	/* Recycle Rx URB : Now, the idle URB is the present one */
	urb->context = NULL;
	self->idle_rx_urb = urb;

	/* Submit the idle URB to replace the URB we've just received.
	 * Do it last to avoid race conditions... Jean II */
	irda_usb_submit(self, skb, next_urb);
}

/*------------------------------------------------------------------*/
/*
 * In case of errors, we want the USB layer to have time to recover.
 * Now, it is time to resubmit ouur Rx URB...
 */
static void irda_usb_rx_defer_expired(unsigned long data)