irlap.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

 */
#ifdef CONFIG_IRDA_ULTRA
void irlap_unitdata_indication(struct irlap_cb *self, struct sk_buff *skb)
{
	IRDA_DEBUG(1, __FUNCTION__ "()\n"); 

	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);
	ASSERT(skb != NULL, return;);

	/* Hide LAP header from IrLMP layer */
	skb_pull(skb, LAP_ADDR_HEADER+LAP_CTRL_HEADER);

	skb_get(skb); /*LEVEL4*/
	irlmp_link_unitdata_indication(self->notify.instance, skb);
}
#endif /* CONFIG_IRDA_ULTRA */

/*
 * Function irlap_disconnect_request (void)
 *
 *    Request to disconnect connection by service user
 */
void irlap_disconnect_request(struct irlap_cb *self) 
{
	IRDA_DEBUG(3, __FUNCTION__ "()\n");

	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);
	
	/* Don't disconnect until all data frames are successfully sent */
	if (skb_queue_len(&self->txq) > 0) {
		self->disconnect_pending = TRUE;
		
		return;
	}

	/* Check if we are in the right state for disconnecting */
	switch (self->state) {
	case LAP_XMIT_P:        /* FALLTROUGH */
	case LAP_XMIT_S:        /* FALLTROUGH */
 	case LAP_CONN:          /* FALLTROUGH */
 	case LAP_RESET_WAIT:    /* FALLTROUGH */
 	case LAP_RESET_CHECK:   
		irlap_do_event(self, DISCONNECT_REQUEST, NULL, NULL);
		break;
	default:
		IRDA_DEBUG(2, __FUNCTION__ "(), disconnect pending!\n");
		self->disconnect_pending = TRUE;
		break;
	}
}

/*
 * Function irlap_disconnect_indication (void)
 *
 *    Disconnect request from other device
 *
 */
void irlap_disconnect_indication(struct irlap_cb *self, LAP_REASON reason) 
{
	IRDA_DEBUG(1, __FUNCTION__ "(), reason=%s\n", lap_reasons[reason]); 

	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);

	/* Flush queues */
	irlap_flush_all_queues(self);
	
	switch (reason) {
	case LAP_RESET_INDICATION:
		IRDA_DEBUG(1, __FUNCTION__ "(), Sending reset request!\n");
		irlap_do_event(self, RESET_REQUEST, NULL, NULL);
		break;
	case LAP_NO_RESPONSE:	   /* FALLTROUGH */	
	case LAP_DISC_INDICATION:  /* FALLTROUGH */
	case LAP_FOUND_NONE:       /* FALLTROUGH */
	case LAP_MEDIA_BUSY:
		irlmp_link_disconnect_indication(self->notify.instance, self, 
						 reason, NULL);
		break;
	default:
		ERROR(__FUNCTION__ "(), Unknown reason %d\n", reason);
	}
}

/*
 * Function irlap_discovery_request (gen_addr_bit)
 *
 *    Start one single discovery operation.
 *
 */
void irlap_discovery_request(struct irlap_cb *self, discovery_t *discovery) 
{
	struct irlap_info info;
	
	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);
	ASSERT(discovery != NULL, return;);
	
	IRDA_DEBUG(4, __FUNCTION__ "(), nslots = %d\n", discovery->nslots);

	ASSERT((discovery->nslots == 1) || (discovery->nslots == 6) ||
	       (discovery->nslots == 8) || (discovery->nslots == 16), 
	       return;);
	
  	/* Discovery is only possible in NDM mode */
	if (self->state != LAP_NDM) {
		IRDA_DEBUG(4, __FUNCTION__ 
			   "(), discovery only possible in NDM mode\n");
		irlap_discovery_confirm(self, NULL);
		/* Note : in theory, if we are not in NDM, we could postpone
		 * the discovery like we do for connection request.
		 * In practice, it's not worth it. If the media was busy,
		 * it's likely next time around it won't be busy. If we are
		 * in REPLY state, we will get passive discovery info & event.
		 * Jean II */
		return;
	}

	/* Check if last discovery request finished in time, or if
	 * it was aborted due to the media busy flag. */
	if (self->discovery_log != NULL) {
		hashbin_delete(self->discovery_log, (FREE_FUNC) kfree);
		self->discovery_log = NULL;
	}
	
	self->discovery_log= hashbin_new(HB_LOCAL);
	
	info.S = discovery->nslots; /* Number of slots */
	info.s = 0; /* Current slot */
	
	self->discovery_cmd = discovery;
	info.discovery = discovery;
	
	/* sysctl_slot_timeout bounds are checked in irsysctl.c - Jean II */
	self->slot_timeout = sysctl_slot_timeout * HZ / 1000;
	
	irlap_do_event(self, DISCOVERY_REQUEST, NULL, &info);
}

/*
 * Function irlap_discovery_confirm (log)
 *
 *    A device has been discovered in front of this station, we
 *    report directly to LMP.
 */
void irlap_discovery_confirm(struct irlap_cb *self, hashbin_t *discovery_log) 
{
	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);
	
	ASSERT(self->notify.instance != NULL, return;);
	
	/* 
	 * Check for successful discovery, since we are then allowed to clear 
	 * the media busy condition (IrLAP 6.13.4 - p.94). This should allow
	 * us to make connection attempts much faster and easier (i.e. no
	 * collisions).
	 * Setting media busy to false will also generate an event allowing
	 * to process pending events in NDM state machine.
	 * Note : the spec doesn't define what's a successful discovery is.
	 * If we want Ultra to work, it's successful even if there is
	 * nobody discovered - Jean II
	 */
	if (discovery_log)
		irda_device_set_media_busy(self->netdev, FALSE);
	
	/* Inform IrLMP */
	irlmp_link_discovery_confirm(self->notify.instance, discovery_log);
}

/*
 * Function irlap_discovery_indication (log)
 *
 *    Somebody is trying to discover us!
 *
 */
void irlap_discovery_indication(struct irlap_cb *self, discovery_t *discovery) 
{
	IRDA_DEBUG(4, __FUNCTION__ "()\n");

	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);
	ASSERT(discovery != NULL, return;);

	ASSERT(self->notify.instance != NULL, return;);

	/* A device is very likely to connect immediately after it performs
	 * a successful discovery. This means that in our case, we are much
	 * more likely to receive a connection request over the medium.
	 * So, we backoff to avoid collisions.
	 * IrLAP spec 6.13.4 suggest 100ms...
	 * Note : this little trick actually make a *BIG* difference. If I set
	 * my Linux box with discovery enabled and one Ultra frame sent every
	 * second, my Palm has no trouble connecting to it every time !
	 * Jean II */
	irda_device_set_media_busy(self->netdev, SMALL);

	irlmp_link_discovery_indication(self->notify.instance, discovery);
}

/*
 * Function irlap_status_indication (quality_of_link)
 *
 *    
 *
 */
void irlap_status_indication(struct irlap_cb *self, int quality_of_link) 
{
	switch (quality_of_link) {
	case STATUS_NO_ACTIVITY:
		MESSAGE("IrLAP, no activity on link!\n");
		break;
	case STATUS_NOISY:
		MESSAGE("IrLAP, noisy link!\n");
		break;
	default:
		break;
	}
	irlmp_status_indication(self->notify.instance,
				quality_of_link, LOCK_NO_CHANGE);
}

/*
 * Function irlap_reset_indication (void)
 *
 *    
 *
 */
void irlap_reset_indication(struct irlap_cb *self)
{
	IRDA_DEBUG(1, __FUNCTION__ "()\n");

	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);
	
	if (self->state == LAP_RESET_WAIT)
		irlap_do_event(self, RESET_REQUEST, NULL, NULL);
	else
		irlap_do_event(self, RESET_RESPONSE, NULL, NULL);
}

/*
 * Function irlap_reset_confirm (void)
 *
 *    
 *
 */
void irlap_reset_confirm(void)
{
 	IRDA_DEBUG(1, __FUNCTION__ "()\n");
}

/*
 * Function irlap_generate_rand_time_slot (S, s)
 *
 *    Generate a random time slot between s and S-1 where
 *    S = Number of slots (0 -> S-1)
 *    s = Current slot
 */
int irlap_generate_rand_time_slot(int S, int s) 
{
	static int rand;
	int slot;
	
	ASSERT((S - s) > 0, return 0;);

	rand += jiffies;
	rand ^= (rand << 12);
	rand ^= (rand >> 20);

	slot = s + rand % (S-s);
	
	ASSERT((slot >= s) || (slot < S), return 0;);
	
	return slot;
}

/*
 * Function irlap_update_nr_received (nr)
 *
 *    Remove all acknowledged frames in current window queue. This code is 
 *    not intuitive and you should not try to change it. If you think it
 *    contains bugs, please mail a patch to the author instead.
 */
void irlap_update_nr_received(struct irlap_cb *self, int nr) 
{
	struct sk_buff *skb = NULL;
	int count = 0;

	/*
         * Remove all the ack-ed frames from the window queue.
         */

	/* 
	 *  Optimize for the common case. It is most likely that the receiver
	 *  will acknowledge all the frames we have sent! So in that case we
	 *  delete all frames stored in window.
	 */
	if (nr == self->vs) {
		while ((skb = skb_dequeue(&self->wx_list)) != NULL) {
			dev_kfree_skb(skb);
		}
		/* The last acked frame is the next to send minus one */
		self->va = nr - 1;
	} else {
		/* Remove all acknowledged frames in current window */
		while ((skb_peek(&self->wx_list) != NULL) && 
		       (((self->va+1) % 8) != nr)) 
		{
			skb = skb_dequeue(&self->wx_list);
			dev_kfree_skb(skb);
			
			self->va = (self->va + 1) % 8;
			count++;
		}
	}
	
	/* Advance window */
	self->window = self->window_size - skb_queue_len(&self->wx_list);
}

/*
 * Function irlap_validate_ns_received (ns)
 *
 *    Validate the next to send (ns) field from received frame.
 */
int irlap_validate_ns_received(struct irlap_cb *self, int ns) 
{
	/*  ns as expected?  */
	if (ns == self->vr)
		return NS_EXPECTED;
	/*
	 *  Stations are allowed to treat invalid NS as unexpected NS
	 *  IrLAP, Recv ... with-invalid-Ns. p. 84
	 */
	return NS_UNEXPECTED;
	
	/* return NR_INVALID; */
}
/*
 * Function irlap_validate_nr_received (nr)
 *
 *    Validate the next to receive (nr) field from received frame.
 *
 */
int irlap_validate_nr_received(struct irlap_cb *self, int nr) 
{
	/*  nr as expected?  */
	if (nr == self->vs) {
		IRDA_DEBUG(4, __FUNCTION__ "(), expected!\n");
		return NR_EXPECTED;
	}

	/*
	 *  unexpected nr? (but within current window), first we check if the 
	 *  ns numbers of the frames in the current window wrap.
	 */
	if (self->va < self->vs) {
		if ((nr >= self->va) && (nr <= self->vs))
			return NR_UNEXPECTED;
	} else {
		if ((nr >= self->va) || (nr <= self->vs)) 
			return NR_UNEXPECTED;
	}
	
	/* Invalid nr!  */
	return NR_INVALID;
}

/*
 * Function irlap_initiate_connection_state ()
 *
 *    Initialize the connection state parameters
 *
 */
void irlap_initiate_connection_state(struct irlap_cb *self) 
{
	IRDA_DEBUG(4, __FUNCTION__ "()\n");
	
	ASSERT(self != NULL, return;);
	ASSERT(self->magic == LAP_MAGIC, return;);

	/* Next to send and next to receive */
	self->vs = self->vr = 0;

	/* Last frame which got acked (0 - 1) % 8 */
	self->va = 7;

	self->window = 1;

	self->remote_busy = FALSE;
	self->retry_count = 0;
}

/*
 * Function irlap_wait_min_turn_around (self, qos)
 *
 *    Wait negotiated minimum turn around time, this function actually sets
 *    the number of BOS's that must be sent before the next transmitted