summaryrefslogtreecommitdiffstats
path: root/c/src/lib/libbsp/m68k/gen68360/network/network.c
blob: 12346ed708e67341f35c0f43a96f3153b179b698 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
/*
 * RTEMS driver for M68360 SCC1 Ethernet
 *
 * W. Eric Norum
 * Saskatchewan Accelerator Laboratory
 * University of Saskatchewan
 * Saskatoon, Saskatchewan, CANADA
 * eric@skatter.usask.ca
 *
 *  $Id$
 */
#include <bsp.h>
#include <rtems/m68k/m68360.h>
#include <stdio.h>
#include <errno.h>
#include <rtems/error.h>
#include <rtems/rtems_bsdnet.h>

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

/*
 * Number of SCCs supported by this driver
 */
#define NSCCDRIVER	1

/*
 * Default number of buffer descriptors set aside for this driver.
 * The number of transmit buffer descriptors has to be quite large
 * since a single frame often uses four or more buffer descriptors.
 */
#define RX_BUF_COUNT     15
#define TX_BUF_COUNT     4
#define TX_BD_PER_BUF    4

/*
 * RTEMS event used by interrupt handler to signal driver tasks.
 * This must not be any of the events used by the network task synchronization.
 */
#define INTERRUPT_EVENT	RTEMS_EVENT_1

/*
 * RTEMS event used to start transmit daemon.
 * This must not be the same as INTERRUPT_EVENT.
 */
#define START_TRANSMIT_EVENT	RTEMS_EVENT_2

/*
 * Receive buffer size -- Allow for a full ethernet packet including CRC
 */
#define RBUF_SIZE	1520

#if (MCLBYTES < RBUF_SIZE)
# error "Driver must have MCLBYTES > RBUF_SIZE"
#endif

/*
 * Per-device data
 */
struct scc_softc {
	struct arpcom		arpcom;
	struct mbuf		**rxMbuf;
	struct mbuf		**txMbuf;
	int			acceptBroadcast;
	int			rxBdCount;
	int			txBdCount;
	int			txBdHead;
	int			txBdTail;
	int			txBdActiveCount;
	m360BufferDescriptor_t	*rxBdBase;
	m360BufferDescriptor_t	*txBdBase;
	rtems_id		rxDaemonTid;
	rtems_id		txDaemonTid;

	/*
	 * Statistics
	 */
	unsigned long	rxInterrupts;
	unsigned long	rxNotFirst;
	unsigned long	rxNotLast;
	unsigned long	rxGiant;
	unsigned long	rxNonOctet;
	unsigned long	rxRunt;
	unsigned long	rxBadCRC;
	unsigned long	rxOverrun;
	unsigned long	rxCollision;

	unsigned long	txInterrupts;
	unsigned long	txDeferred;
	unsigned long	txHeartbeat;
	unsigned long	txLateCollision;
	unsigned long	txRetryLimit;
	unsigned long	txUnderrun;
	unsigned long	txLostCarrier;
	unsigned long	txRawWait;
	unsigned long	txCoalesced;
	unsigned long	txCoalesceFailed;
	unsigned long	txRetry;
};
static struct scc_softc scc_softc[NSCCDRIVER];

/*
 * SCC1 interrupt handler
 */
static rtems_isr
m360Enet_interrupt_handler (rtems_vector_number v)
{
	/*
	 * Frame received?
	 */
	if ((m360.scc1.sccm & 0x8) && (m360.scc1.scce & 0x8)) {
		m360.scc1.scce = 0x8;
		m360.scc1.sccm &= ~0x8;
		scc_softc[0].rxInterrupts++;
		rtems_event_send (scc_softc[0].rxDaemonTid, INTERRUPT_EVENT);
	}

	/*
	 * Buffer transmitted or transmitter error?
	 */
	if ((m360.scc1.sccm & 0x12) && (m360.scc1.scce & 0x12)) {
		m360.scc1.scce = 0x12;
		m360.scc1.sccm &= ~0x12;
		scc_softc[0].txInterrupts++;
		rtems_event_send (scc_softc[0].txDaemonTid, INTERRUPT_EVENT);
	}
	m360.cisr = 1UL << 30;	/* Clear SCC1 interrupt-in-service bit */
}

/*
 * Initialize the ethernet hardware
 */
static void
m360Enet_initialize_hardware (struct scc_softc *sc)
{
	int i;
	unsigned char *hwaddr;
	rtems_status_code status;
	rtems_isr_entry old_handler;

	/*
	 * Configure port A CLK1, CLK2, TXD1 and RXD1 pins
	 */
	m360.papar |=  0x303;
	m360.padir &= ~0x303;
	m360.paodr &= ~0x303;

	/*
	 * Configure port C CTS1* and CD1* pins
	 */
	m360.pcpar &= ~0x30;
	m360.pcdir &= ~0x30;
	m360.pcso  |=  0x30;

	/*
	 * Connect CLK1 and CLK2 to SCC1
	 */
	m360.sicr &= ~0xFF;
	m360.sicr |= (5 << 3) | 4;

	/*
	 * Allocate mbuf pointers
	 */
	sc->rxMbuf = malloc (sc->rxBdCount * sizeof *sc->rxMbuf, M_MBUF, M_NOWAIT);
	sc->txMbuf = malloc (sc->txBdCount * sizeof *sc->txMbuf, M_MBUF, M_NOWAIT);
	if (!sc->rxMbuf || !sc->txMbuf)
		rtems_panic ("No memory for mbuf pointers");

	/*
	 * Set receiver and transmitter buffer descriptor bases
	 */
	sc->rxBdBase = M360AllocateBufferDescriptors(sc->rxBdCount);
	sc->txBdBase = M360AllocateBufferDescriptors(sc->txBdCount);
	m360.scc1p.rbase = (char *)sc->rxBdBase - (char *)&m360;
	m360.scc1p.tbase = (char *)sc->txBdBase - (char *)&m360;

	/*
	 * Send "Init parameters" command
	 */
	M360ExecuteRISC (M360_CR_OP_INIT_RX_TX | M360_CR_CHAN_SCC1);

	/*
	 * Set receive and transmit function codes
	 */
	m360.scc1p.rfcr = M360_RFCR_MOT | M360_RFCR_DMA_SPACE;
	m360.scc1p.tfcr = M360_TFCR_MOT | M360_TFCR_DMA_SPACE;

	/*
	 * Set maximum receive buffer length
	 */
	m360.scc1p.mrblr = RBUF_SIZE;

	/*
	 * Set CRC parameters
	 */
	m360.scc1p.un.ethernet.c_pres = 0xFFFFFFFF;
	m360.scc1p.un.ethernet.c_mask = 0xDEBB20E3;

	/*
	 * Clear diagnostic counters
	 */
	m360.scc1p.un.ethernet.crcec = 0;
	m360.scc1p.un.ethernet.alec = 0;
	m360.scc1p.un.ethernet.disfc = 0;

	/*
	 * Set pad value
	 */
	m360.scc1p.un.ethernet.pads = 0x8888;

	/*
	 * Set retry limit
	 */
	m360.scc1p.un.ethernet.ret_lim = 15;

	/*
	 * Set maximum and minimum frame length
	 */
	m360.scc1p.un.ethernet.mflr = 1518;
	m360.scc1p.un.ethernet.minflr = 64;
	m360.scc1p.un.ethernet.maxd1 = RBUF_SIZE;
	m360.scc1p.un.ethernet.maxd2 = RBUF_SIZE;

	/*
	 * Clear group address hash table
	 */
	m360.scc1p.un.ethernet.gaddr1 = 0;
	m360.scc1p.un.ethernet.gaddr2 = 0;
	m360.scc1p.un.ethernet.gaddr3 = 0;
	m360.scc1p.un.ethernet.gaddr4 = 0;

	/*
	 * Set our physical address
	 */
	hwaddr = sc->arpcom.ac_enaddr;
	m360.scc1p.un.ethernet.paddr_h = (hwaddr[5] << 8) | hwaddr[4];
	m360.scc1p.un.ethernet.paddr_m = (hwaddr[3] << 8) | hwaddr[2];
	m360.scc1p.un.ethernet.paddr_l = (hwaddr[1] << 8) | hwaddr[0];

	/*
	 * Aggressive retry
	 */
	m360.scc1p.un.ethernet.p_per = 0;

	/*
	 * Clear individual address hash table
	 */
	m360.scc1p.un.ethernet.iaddr1 = 0;
	m360.scc1p.un.ethernet.iaddr2 = 0;
	m360.scc1p.un.ethernet.iaddr3 = 0;
	m360.scc1p.un.ethernet.iaddr4 = 0;

	/*
	 * Set up receive buffer descriptors
	 */
	for (i = 0 ; i < sc->rxBdCount ; i++)
		(sc->rxBdBase + i)->status = 0;

	/*
	 * Set up transmit buffer descriptors
	 */
	for (i = 0 ; i < sc->txBdCount ; i++) {
		(sc->txBdBase + i)->status = 0;
		sc->txMbuf[i] = NULL;
	}
	sc->txBdHead = sc->txBdTail = 0;
	sc->txBdActiveCount = 0;

	/*
	 * Clear any outstanding events
	 */
	m360.scc1.scce = 0xFFFF;

	/*
	 * Set up interrupts
	 */
	status = rtems_interrupt_catch (m360Enet_interrupt_handler,
						(m360.cicr & 0xE0) | 0x1E,
						&old_handler);
	if (status != RTEMS_SUCCESSFUL)
		rtems_panic ("Can't attach M360 SCC1 interrupt handler: %s\n",
						rtems_status_text (status));
	m360.scc1.sccm = 0;	/* No interrupts unmasked till necessary */
	m360.cimr |= (1UL << 30);	/* Enable SCC1 interrupt */

	/*
	 * Set up General SCC Mode Register
	 * Ethernet configuration
	 */
	m360.scc1.gsmr_h = 0x0;
	m360.scc1.gsmr_l = 0x1088000c;

	/*
	 * Set up data synchronization register
	 * Ethernet synchronization pattern
	 */
	m360.scc1.dsr = 0xd555;

	/*
	 * Set up protocol-specific mode register
	 *	Heartbeat check
	 *	No force collision
	 *	Discard short frames
	 *	Individual address mode
	 *	Ethernet CRC
	 *	Not promisuous
	 *	Ignore/accept broadcast packets as specified
	 *	Normal backoff timer
	 *	No loopback
	 *	No input sample at end of frame
	 *	64-byte limit for late collision
	 *	Wait 22 bits before looking for start of frame delimiter
	 *	Disable full-duplex operation
	 */
	m360.scc1.psmr = 0x880A | (sc->acceptBroadcast ? 0 : 0x100);

	/*
	 * Enable the TENA (RTS1*) pin
	 */
#if (defined (M68360_ATLAS_HSB))
	m360.pbpar |= 0x1000;
	m360.pbdir |= 0x1000;
#else
	m360.pcpar |=  0x1;
	m360.pcdir &= ~0x1;
#endif
}

/*
 * Soak up buffer descriptors that have been sent
 * Note that a buffer descriptor can't be retired as soon as it becomes
 * ready.  The MC68360 Errata (May 96) says that, "If an Ethernet frame is
 *  made up of multiple buffers, the user should not reuse the first buffer
 * descriptor until the last buffer descriptor of the frame has had its
 * ready bit cleared by the CPM".
 */
static void
m360Enet_retire_tx_bd (struct scc_softc *sc)
{
	uint16_t         status;
	int i;
	int nRetired;
	struct mbuf *m, *n;
	int retries = 0;
	int saveStatus = 0;

	i = sc->txBdTail;
	nRetired = 0;
	while ((sc->txBdActiveCount != 0)
	   &&  (((status = (sc->txBdBase + i)->status) & M360_BD_READY) == 0)) {
		/*
		 * Check for errors which stop the transmitter.
		 */
		if (status & (M360_BD_LATE_COLLISION |
				M360_BD_RETRY_LIMIT |
				M360_BD_UNDERRUN)) {
			int j;

			if (status & M360_BD_LATE_COLLISION)
				sc->txLateCollision++;
			if (status & M360_BD_RETRY_LIMIT)
				sc->txRetryLimit++;
			if (status & M360_BD_UNDERRUN)
				sc->txUnderrun++;

			/*
			 * Reenable buffer descriptors
			 */
			j = sc->txBdTail;
			for (;;) {
				status = (sc->txBdBase + j)->status;
				if (status & M360_BD_READY)
					break;
				(sc->txBdBase + j)->status = M360_BD_READY |
					(status & (M360_BD_PAD |
						   M360_BD_WRAP |
						   M360_BD_INTERRUPT |
						   M360_BD_LAST |
						   M360_BD_TX_CRC));
				if (status & M360_BD_LAST)
					break;
				if (++j == sc->txBdCount)
					j = 0;
			}

			/*
			 * Move transmitter back to the first
			 * buffer descriptor in the frame.
			 */
			m360.scc1p._tbptr = m360.scc1p.tbase +
				sc->txBdTail * sizeof (m360BufferDescriptor_t);

			/*
			 * Restart the transmitter
			 */
			M360ExecuteRISC (M360_CR_OP_RESTART_TX | M360_CR_CHAN_SCC1);
			continue;
		}
		saveStatus |= status;
		retries += (status >> 2) & 0xF;
		nRetired++;
		if (status & M360_BD_LAST) {
			/*
			 * A full frame has been transmitted.
			 * Free all the associated buffer descriptors.
			 */
			if (saveStatus & M360_BD_DEFER)
				sc->txDeferred++;
			if (saveStatus & M360_BD_HEARTBEAT)
				sc->txHeartbeat++;
			if (saveStatus & M360_BD_CARRIER_LOST)
				sc->txLostCarrier++;
			saveStatus = 0;
			sc->txRetry += retries;
			retries = 0;
			sc->txBdActiveCount -= nRetired;
			while (nRetired) {
				nRetired--;
				m = sc->txMbuf[sc->txBdTail];
				MFREE (m, n);
				if (++sc->txBdTail == sc->txBdCount)
					sc->txBdTail = 0;
			}
		}
		if (++i == sc->txBdCount)
			i = 0;
	}
}

/*
 * SCC reader task
 */
static void
scc_rxDaemon (void *arg)
{
	struct scc_softc *sc = (struct scc_softc *)arg;
	struct ifnet *ifp = &sc->arpcom.ac_if;
	struct mbuf *m;
	uint16_t         status;
	volatile m360BufferDescriptor_t *rxBd;
	int rxBdIndex;

	/*
	 * Allocate space for incoming packets and start reception
	 */
	for (rxBdIndex = 0 ; ;) {
		rxBd = sc->rxBdBase + rxBdIndex;
		MGETHDR (m, M_WAIT, MT_DATA);
		MCLGET (m, M_WAIT);
		m->m_pkthdr.rcvif = ifp;
		sc->rxMbuf[rxBdIndex] = m;
		rxBd->buffer = mtod (m, void *);
		if (++rxBdIndex == sc->rxBdCount) {
			rxBd->status = M360_BD_EMPTY | M360_BD_INTERRUPT | M360_BD_WRAP;
			break;
		}
		rxBd->status = M360_BD_EMPTY | M360_BD_INTERRUPT;
	}

	/*
	 * Input packet handling loop
	 */
	rxBdIndex = 0;
	for (;;) {
		rxBd = sc->rxBdBase + rxBdIndex;

		/*
		 * Wait for packet if there's not one ready
		 */
		if ((status = rxBd->status) & M360_BD_EMPTY) {
			/*
			 * Clear old events
			 */
			m360.scc1.scce = 0x8;

			/*
			 * Wait for packet
			 * Note that the buffer descriptor is checked
			 * *before* the event wait -- this catches the
			 * possibility that a packet arrived between the
			 * `if' above, and the clearing of the event register.
			 */
			while ((status = rxBd->status) & M360_BD_EMPTY) {
				rtems_interrupt_level level;
				rtems_event_set events;

				/*
				 * Unmask RXF (Full frame received) event
				 */
				rtems_interrupt_disable (level);
				m360.scc1.sccm |= 0x8;
				rtems_interrupt_enable (level);

				rtems_bsdnet_event_receive (INTERRUPT_EVENT,
						RTEMS_WAIT|RTEMS_EVENT_ANY,
						RTEMS_NO_TIMEOUT,
						&events);
			}
		}

		/*
		 * Check that packet is valid
		 */
		if ((status & (M360_BD_LAST |
				M360_BD_FIRST_IN_FRAME |
				M360_BD_LONG |
				M360_BD_NONALIGNED |
				M360_BD_SHORT |
				M360_BD_CRC_ERROR |
				M360_BD_OVERRUN |
				M360_BD_COLLISION)) ==
						(M360_BD_LAST |
						M360_BD_FIRST_IN_FRAME)) {
			/*
			 * Pass the packet up the chain.
			 * FIXME: Packet filtering hook could be done here.
			 */
			struct ether_header *eh;

			m = sc->rxMbuf[rxBdIndex];
			m->m_len = m->m_pkthdr.len = rxBd->length -
						sizeof(uint32_t) -
						sizeof(struct ether_header);
			eh = mtod (m, struct ether_header *);
			m->m_data += sizeof(struct ether_header);
			ether_input (ifp, eh, m);

			/*
			 * Allocate a new mbuf
			 */
			MGETHDR (m, M_WAIT, MT_DATA);
			MCLGET (m, M_WAIT);
			m->m_pkthdr.rcvif = ifp;
			sc->rxMbuf[rxBdIndex] = m;
			rxBd->buffer = mtod (m, void *);
		}
		else {
			/*
			 * Something went wrong with the reception
			 */
			if (!(status & M360_BD_LAST))
				sc->rxNotLast++;
			if (!(status & M360_BD_FIRST_IN_FRAME))
				sc->rxNotFirst++;
			if (status & M360_BD_LONG)
				sc->rxGiant++;
			if (status & M360_BD_NONALIGNED)
				sc->rxNonOctet++;
			if (status & M360_BD_SHORT)
				sc->rxRunt++;
			if (status & M360_BD_CRC_ERROR)
				sc->rxBadCRC++;
			if (status & M360_BD_OVERRUN)
				sc->rxOverrun++;
			if (status & M360_BD_COLLISION)
				sc->rxCollision++;
		}

		/*
		 * Reenable the buffer descriptor
		 */
		rxBd->status = (status & (M360_BD_WRAP | M360_BD_INTERRUPT)) | M360_BD_EMPTY;

		/*
		 * Move to next buffer descriptor
		 */
		if (++rxBdIndex == sc->rxBdCount)
			rxBdIndex = 0;
	}
}

static void
sendpacket (struct ifnet *ifp, struct mbuf *m)
{
	struct scc_softc *sc = ifp->if_softc;
	volatile m360BufferDescriptor_t *firstTxBd, *txBd;
	struct mbuf *l = NULL;
	uint16_t         status;
	int nAdded;

	/*
	 * Free up buffer descriptors
	 */
	m360Enet_retire_tx_bd (sc);

	/*
	 * Set up the transmit buffer descriptors.
	 * No need to pad out short packets since the
	 * hardware takes care of that automatically.
	 * No need to copy the packet to a contiguous buffer
	 * since the hardware is capable of scatter/gather DMA.
	 */
	status = 0;
	nAdded = 0;
	txBd = firstTxBd = sc->txBdBase + sc->txBdHead;
	while (m) {
		/*
		 * There are more mbufs in the packet than there
		 * are transmit buffer descriptors.
		 * Coalesce into a single buffer.
		 */
		if (nAdded == sc->txBdCount) {
			struct mbuf *nm;
			int j;
			char *dest;

			/*
			 * Get the pointer to the first mbuf of the packet
			 */
			if (sc->txBdTail != sc->txBdHead)
				rtems_panic ("sendpacket coalesce");
			m = sc->txMbuf[sc->txBdTail];

			/*
			 * Rescind the buffer descriptor READY bits
			 */
			for (j = 0 ; j < sc->txBdCount ; j++)
				(sc->txBdBase + j)->status = 0;

			/*
			 * Allocate an mbuf cluster
			 * Toss the packet if allocation fails
			 */
			MGETHDR (nm, M_DONTWAIT, MT_DATA);
			if (nm == NULL) {
				sc->txCoalesceFailed++;
				m_freem (m);
				return;
			}
			MCLGET (nm, M_DONTWAIT);
			if (nm->m_ext.ext_buf == NULL) {
				sc->txCoalesceFailed++;
				m_freem (m);
				m_free (nm);
				return;
			}
			nm->m_pkthdr = m->m_pkthdr;
			nm->m_len = nm->m_pkthdr.len;

			/*
			 * Copy data from packet chain to mbuf cluster
			 */
			sc->txCoalesced++;
			dest = nm->m_ext.ext_buf;
			while (m) {
				struct mbuf *n;

				if (m->m_len) {
					memcpy (dest, mtod(m, caddr_t), m->m_len);
					dest += m->m_len;
				}
				MFREE (m, n);
				m = n;
			}

			/*
			 * Redo the send with the new mbuf cluster
			 */
			m = nm;
			nAdded = 0;
			status = 0;
			continue;
		}

		/*
		 * Wait for buffer descriptor to become available.
		 */
		if ((sc->txBdActiveCount + nAdded) == sc->txBdCount) {
			/*
			 * Clear old events
			 */
			m360.scc1.scce = 0x12;

			/*
			 * Wait for buffer descriptor to become available.
			 * Note that the buffer descriptors are checked
			 * *before* entering the wait loop -- this catches
			 * the possibility that a buffer descriptor became
			 * available between the `if' above, and the clearing
			 * of the event register.
			 * This is to catch the case where the transmitter
			 * stops in the middle of a frame -- and only the
			 * last buffer descriptor in a frame can generate
			 * an interrupt.
			 */
			m360Enet_retire_tx_bd (sc);
			while ((sc->txBdActiveCount + nAdded) == sc->txBdCount) {
				rtems_interrupt_level level;
				rtems_event_set events;

				/*
				 * Unmask TXB (buffer transmitted) and
				 * TXE (transmitter error) events.
				 */
				rtems_interrupt_disable (level);
				m360.scc1.sccm |= 0x12;
				rtems_interrupt_enable (level);
				rtems_bsdnet_event_receive (INTERRUPT_EVENT,
						RTEMS_WAIT|RTEMS_EVENT_ANY,
						RTEMS_NO_TIMEOUT,
						&events);
				m360Enet_retire_tx_bd (sc);
			}
		}

		/*
		 * The IP fragmentation routine in ip_output
		 * can produce packet fragments with zero length.
		 */
		if (m->m_len) {
			/*
			 * Fill in the buffer descriptor.
			 * Don't set the READY flag in the first buffer
			 * descriptor till the whole packet has been readied.
			 */
			txBd = sc->txBdBase + sc->txBdHead;
			txBd->buffer = mtod (m, void *);
			txBd->length = m->m_len;
			sc->txMbuf[sc->txBdHead] = m;
			status = nAdded ? M360_BD_READY : 0;
			if (++sc->txBdHead == sc->txBdCount) {
				status |= M360_BD_WRAP;
				sc->txBdHead = 0;
			}
			txBd->status = status;
			l = m;
			m = m->m_next;
			nAdded++;
		}
		else {
			/*
			 * Just toss empty mbufs
			 */
			struct mbuf *n;
			MFREE (m, n);
			m = n;
			if (l != NULL)
				l->m_next = m;
		}
	}
	if (nAdded) {
		/*
		 * Send the packet
		 */
		txBd->status = status | M360_BD_PAD | M360_BD_LAST | M360_BD_TX_CRC | M360_BD_INTERRUPT;
		firstTxBd->status |= M360_BD_READY;
		sc->txBdActiveCount += nAdded;
	}
}

/*
 * Driver transmit daemon
 */
void
scc_txDaemon (void *arg)
{
	struct scc_softc *sc = (struct scc_softc *)arg;
	struct ifnet *ifp = &sc->arpcom.ac_if;
	struct mbuf *m;
	rtems_event_set events;

	for (;;) {
		/*
		 * Wait for packet
		 */
		rtems_bsdnet_event_receive (START_TRANSMIT_EVENT, RTEMS_EVENT_ANY | RTEMS_WAIT, RTEMS_NO_TIMEOUT, &events);

		/*
		 * Send packets till queue is empty
		 */
		for (;;) {
			/*
			 * Get the next mbuf chain to transmit.
			 */
			IF_DEQUEUE(&ifp->if_snd, m);
			if (!m)
				break;
			sendpacket (ifp, m);
		}
		ifp->if_flags &= ~IFF_OACTIVE;
	}
}

/*
 * Send packet (caller provides header).
 */
static void
scc_start (struct ifnet *ifp)
{
	struct scc_softc *sc = ifp->if_softc;

	rtems_event_send (sc->txDaemonTid, START_TRANSMIT_EVENT);
	ifp->if_flags |= IFF_OACTIVE;
}

/*
 * Initialize and start the device
 */
static void
scc_init (void *arg)
{
	struct scc_softc *sc = arg;
	struct ifnet *ifp = &sc->arpcom.ac_if;

	if (sc->txDaemonTid == 0) {

		/*
		 * Set up SCC hardware
		 */
		m360Enet_initialize_hardware (sc);

		/*
		 * Start driver tasks
		 */
		sc->txDaemonTid = rtems_bsdnet_newproc ("SCtx", 4096, scc_txDaemon, sc);
		sc->rxDaemonTid = rtems_bsdnet_newproc ("SCrx", 4096, scc_rxDaemon, sc);

	}

	/*
	 * Set flags appropriately
	 */
	if (ifp->if_flags & IFF_PROMISC)
		m360.scc1.psmr |= 0x200;
	else
		m360.scc1.psmr &= ~0x200;

	/*
	 * Tell the world that we're running.
	 */
	ifp->if_flags |= IFF_RUNNING;

	/*
	 * Enable receiver and transmitter
	 */
	m360.scc1.gsmr_l |= 0x30;
}

/*
 * Stop the device
 */
static void
scc_stop (struct scc_softc *sc)
{
	struct ifnet *ifp = &sc->arpcom.ac_if;

	ifp->if_flags &= ~IFF_RUNNING;

	/*
	 * Shut down receiver and transmitter
	 */
	m360.scc1.gsmr_l &= ~0x30;
}

/*
 * Show interface statistics
 */
static void
scc_stats (struct scc_softc *sc)
{
	printf ("      Rx Interrupts:%-8lu", sc->rxInterrupts);
	printf ("       Not First:%-8lu", sc->rxNotFirst);
	printf ("        Not Last:%-8lu\n", sc->rxNotLast);
	printf ("              Giant:%-8lu", sc->rxGiant);
	printf ("            Runt:%-8lu", sc->rxRunt);
	printf ("       Non-octet:%-8lu\n", sc->rxNonOctet);
	printf ("            Bad CRC:%-8lu", sc->rxBadCRC);
	printf ("         Overrun:%-8lu", sc->rxOverrun);
	printf ("       Collision:%-8lu\n", sc->rxCollision);
	printf ("          Discarded:%-8lu\n", (unsigned long)m360.scc1p.un.ethernet.disfc);

	printf ("      Tx Interrupts:%-8lu", sc->txInterrupts);
	printf ("        Deferred:%-8lu", sc->txDeferred);
	printf (" Missed Hearbeat:%-8lu\n", sc->txHeartbeat);
	printf ("         No Carrier:%-8lu", sc->txLostCarrier);
	printf ("Retransmit Limit:%-8lu", sc->txRetryLimit);
	printf ("  Late Collision:%-8lu\n", sc->txLateCollision);
	printf ("           Underrun:%-8lu", sc->txUnderrun);
	printf (" Raw output wait:%-8lu", sc->txRawWait);
	printf ("       Coalesced:%-8lu\n", sc->txCoalesced);
	printf ("    Coalesce failed:%-8lu", sc->txCoalesceFailed);
	printf ("         Retries:%-8lu\n", sc->txRetry);
}

/*
 * Driver ioctl handler
 */
static int
scc_ioctl (struct ifnet *ifp, ioctl_command_t command, caddr_t data)
{
	struct scc_softc *sc = ifp->if_softc;
	int error = 0;

	switch (command) {
	case SIOCGIFADDR:
	case SIOCSIFADDR:
		ether_ioctl (ifp, command, data);
		break;

	case SIOCSIFFLAGS:
		switch (ifp->if_flags & (IFF_UP | IFF_RUNNING)) {
		case IFF_RUNNING:
			scc_stop (sc);
			break;

		case IFF_UP:
			scc_init (sc);
			break;

		case IFF_UP | IFF_RUNNING:
			scc_stop (sc);
			scc_init (sc);
			break;

		default:
			break;
		}
		break;

	case SIO_RTEMS_SHOW_STATS:
		scc_stats (sc);
		break;

	/*
	 * FIXME: All sorts of multicast commands need to be added here!
	 */
	default:
		error = EINVAL;
		break;
	}
	return error;
}

/*
 * Attach an SCC driver to the system
 */
int
rtems_scc1_driver_attach (struct rtems_bsdnet_ifconfig *config, int attaching)
{
	struct scc_softc *sc;
	struct ifnet *ifp;
	int mtu;
	int unitNumber;
	char *unitName;

	/*
	 * Make sure we're really being attached
	 */
	if (!attaching) {
		printf ("SCC1 driver can not be detached.\n");
		return 0;
	}

	/*
 	 * Parse driver name
	 */
	if ((unitNumber = rtems_bsdnet_parse_driver_name (config, &unitName)) < 0)
		return 0;

	/*
	 * Is driver free?
	 */
	if ((unitNumber <= 0) || (unitNumber > NSCCDRIVER)) {
		printf ("Bad SCC unit number.\n");
		return 0;
	}
	sc = &scc_softc[unitNumber - 1];
	ifp = &sc->arpcom.ac_if;
	if (ifp->if_softc != NULL) {
		printf ("Driver already in use.\n");
		return 0;
	}

	/*
	 * Process options
	 */
	if (config->hardware_address) {
		memcpy (sc->arpcom.ac_enaddr, config->hardware_address, ETHER_ADDR_LEN);
	}
	else {
		/*
		 * The first 4 bytes of the bootstrap prom
		 * contain the value loaded into the stack
		 * pointer as part of the CPU32's hardware
		 * reset exception handler.  The following
		 * 4 bytes contain the value loaded into the
		 * program counter.  The boards' Ethernet
		 * address is stored in the six bytes
		 * immediately preceding this initial
		 * program counter value.
		 *
		 * See start360/start360.s.
		 */
		extern void *_RomBase;	/* From linkcmds */
		const unsigned long *ExceptionVectors;
		const unsigned char *entryPoint;

		/*
		 * Sanity check -- assume entry point must be
		 * within 1 MByte of beginning of boot ROM.
		 */
		ExceptionVectors = (const unsigned long *)&_RomBase;
		entryPoint = (const unsigned char *)ExceptionVectors[1];
		if (((unsigned long)entryPoint - (unsigned long)ExceptionVectors)
					>= (1 * 1024 * 1024)) {
			printf ("Warning -- Ethernet address can not be found in bootstrap PROM.\n");
			sc->arpcom.ac_enaddr[0] = 0x08;
			sc->arpcom.ac_enaddr[1] = 0xF3;
			sc->arpcom.ac_enaddr[2] = 0x3E;
			sc->arpcom.ac_enaddr[3] = 0xC2;
			sc->arpcom.ac_enaddr[4] = 0x7E;
			sc->arpcom.ac_enaddr[5] = 0x38;
		}
		else {
			memcpy (sc->arpcom.ac_enaddr, entryPoint - ETHER_ADDR_LEN, ETHER_ADDR_LEN);
		}
	}
	if (config->mtu)
		mtu = config->mtu;
	else
		mtu = ETHERMTU;
	if (config->rbuf_count)
		sc->rxBdCount = config->rbuf_count;
	else
		sc->rxBdCount = RX_BUF_COUNT;
	if (config->xbuf_count)
		sc->txBdCount = config->xbuf_count;
	else
		sc->txBdCount = TX_BUF_COUNT * TX_BD_PER_BUF;
	sc->acceptBroadcast = !config->ignore_broadcast;

	/*
	 * Set up network interface values
	 */
	ifp->if_softc = sc;
	ifp->if_unit = unitNumber;
	ifp->if_name = unitName;
	ifp->if_mtu = mtu;
	ifp->if_init = scc_init;
	ifp->if_ioctl = scc_ioctl;
	ifp->if_start = scc_start;
	ifp->if_output = ether_output;
	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX;
	if (ifp->if_snd.ifq_maxlen == 0)
		ifp->if_snd.ifq_maxlen = ifqmaxlen;

	/*
	 * Attach the interface
	 */
	if_attach (ifp);
	ether_ifattach (ifp);
	return 1;
}