aboutsummaryrefslogtreecommitdiff
path: root/drivers/net/ethernet/3com/3c501.c
blob: 5420f6de27dfa1bdd9ee4fb626e7c6537792b854 (plain)
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
/* 3c501.c: A 3Com 3c501 Ethernet driver for Linux. */
/*
    Written 1992,1993,1994  Donald Becker

    Copyright 1993 United States Government as represented by the
    Director, National Security Agency.  This software may be used and
    distributed according to the terms of the GNU General Public License,
    incorporated herein by reference.

    This is a device driver for the 3Com Etherlink 3c501.
    Do not purchase this card, even as a joke.  It's performance is horrible,
    and it breaks in many ways.

    The original author may be reached as becker@scyld.com, or C/O
	Scyld Computing Corporation
	410 Severn Ave., Suite 210
	Annapolis MD 21403

    Fixed (again!) the missing interrupt locking on TX/RX shifting.
	Alan Cox <alan@lxorguk.ukuu.org.uk>

    Removed calls to init_etherdev since they are no longer needed, and
    cleaned up modularization just a bit. The driver still allows only
    the default address for cards when loaded as a module, but that's
    really less braindead than anyone using a 3c501 board. :)
		    19950208 (invid@msen.com)

    Added traps for interrupts hitting the window as we clear and TX load
    the board. Now getting 150K/second FTP with a 3c501 card. Still playing
    with a TX-TX optimisation to see if we can touch 180-200K/second as seems
    theoretically maximum.
		19950402 Alan Cox <alan@lxorguk.ukuu.org.uk>

    Cleaned up for 2.3.x because we broke SMP now.
		20000208 Alan Cox <alan@lxorguk.ukuu.org.uk>

    Check up pass for 2.5. Nothing significant changed
		20021009 Alan Cox <alan@lxorguk.ukuu.org.uk>

    Fixed zero fill corner case
		20030104 Alan Cox <alan@lxorguk.ukuu.org.uk>


   For the avoidance of doubt the "preferred form" of this code is one which
   is in an open non patent encumbered format. Where cryptographic key signing
   forms part of the process of creating an executable the information
   including keys needed to generate an equivalently functional executable
   are deemed to be part of the source code.

*/


/**
 * DOC: 3c501 Card Notes
 *
 *  Some notes on this thing if you have to hack it.  [Alan]
 *
 *  Some documentation is available from 3Com. Due to the boards age
 *  standard responses when you ask for this will range from 'be serious'
 *  to 'give it to a museum'. The documentation is incomplete and mostly
 *  of historical interest anyway.
 *
 *  The basic system is a single buffer which can be used to receive or
 *  transmit a packet. A third command mode exists when you are setting
 *  things up.
 *
 *  If it's transmitting it's not receiving and vice versa. In fact the
 *  time to get the board back into useful state after an operation is
 *  quite large.
 *
 *  The driver works by keeping the board in receive mode waiting for a
 *  packet to arrive. When one arrives it is copied out of the buffer
 *  and delivered to the kernel. The card is reloaded and off we go.
 *
 *  When transmitting lp->txing is set and the card is reset (from
 *  receive mode) [possibly losing a packet just received] to command
 *  mode. A packet is loaded and transmit mode triggered. The interrupt
 *  handler runs different code for transmit interrupts and can handle
 *  returning to receive mode or retransmissions (yes you have to help
 *  out with those too).
 *
 * DOC: Problems
 *
 *  There are a wide variety of undocumented error returns from the card
 *  and you basically have to kick the board and pray if they turn up. Most
 *  only occur under extreme load or if you do something the board doesn't
 *  like (eg touching a register at the wrong time).
 *
 *  The driver is less efficient than it could be. It switches through
 *  receive mode even if more transmits are queued. If this worries you buy
 *  a real Ethernet card.
 *
 *  The combination of slow receive restart and no real multicast
 *  filter makes the board unusable with a kernel compiled for IP
 *  multicasting in a real multicast environment. That's down to the board,
 *  but even with no multicast programs running a multicast IP kernel is
 *  in group 224.0.0.1 and you will therefore be listening to all multicasts.
 *  One nv conference running over that Ethernet and you can give up.
 *
 */

#define DRV_NAME	"3c501"
#define DRV_VERSION	"2002/10/09"


static const char version[] =
	DRV_NAME ".c: " DRV_VERSION " Alan Cox (alan@lxorguk.ukuu.org.uk).\n";

/*
 *	Braindamage remaining:
 *	The 3c501 board.
 */

#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/ethtool.h>
#include <linux/delay.h>
#include <linux/bitops.h>

#include <asm/uaccess.h>
#include <asm/io.h>

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/init.h>

#include "3c501.h"

/*
 *	The boilerplate probe code.
 */

static int io = 0x280;
static int irq = 5;
static int mem_start;

/**
 * el1_probe:		-	probe for a 3c501
 * @dev: The device structure passed in to probe.
 *
 * This can be called from two places. The network layer will probe using
 * a device structure passed in with the probe information completed. For a
 * modular driver we use #init_module to fill in our own structure and probe
 * for it.
 *
 * Returns 0 on success. ENXIO if asked not to probe and ENODEV if asked to
 * probe and failing to find anything.
 */

struct net_device * __init el1_probe(int unit)
{
	struct net_device *dev = alloc_etherdev(sizeof(struct net_local));
	static const unsigned ports[] = { 0x280, 0x300, 0};
	const unsigned *port;
	int err = 0;

	if (!dev)
		return ERR_PTR(-ENOMEM);

	if (unit >= 0) {
		sprintf(dev->name, "eth%d", unit);
		netdev_boot_setup_check(dev);
		io = dev->base_addr;
		irq = dev->irq;
		mem_start = dev->mem_start & 7;
	}

	if (io > 0x1ff) {	/* Check a single specified location. */
		err = el1_probe1(dev, io);
	} else if (io != 0) {
		err = -ENXIO;		/* Don't probe at all. */
	} else {
		for (port = ports; *port && el1_probe1(dev, *port); port++)
			;
		if (!*port)
			err = -ENODEV;
	}
	if (err)
		goto out;
	err = register_netdev(dev);
	if (err)
		goto out1;
	return dev;
out1:
	release_region(dev->base_addr, EL1_IO_EXTENT);
out:
	free_netdev(dev);
	return ERR_PTR(err);
}

static const struct net_device_ops el_netdev_ops = {
	.ndo_open		= el_open,
	.ndo_stop		= el1_close,
	.ndo_start_xmit 	= el_start_xmit,
	.ndo_tx_timeout		= el_timeout,
	.ndo_set_multicast_list = set_multicast_list,
	.ndo_change_mtu		= eth_change_mtu,
	.ndo_set_mac_address 	= eth_mac_addr,
	.ndo_validate_addr	= eth_validate_addr,
};

/**
 *	el1_probe1:
 *	@dev: The device structure to use
 *	@ioaddr: An I/O address to probe at.
 *
 *	The actual probe. This is iterated over by #el1_probe in order to
 *	check all the applicable device locations.
 *
 *	Returns 0 for a success, in which case the device is activated,
 *	EAGAIN if the IRQ is in use by another driver, and ENODEV if the
 *	board cannot be found.
 */

static int __init el1_probe1(struct net_device *dev, int ioaddr)
{
	struct net_local *lp;
	const char *mname;		/* Vendor name */
	unsigned char station_addr[6];
	int autoirq = 0;
	int i;

	/*
	 *	Reserve I/O resource for exclusive use by this driver
	 */

	if (!request_region(ioaddr, EL1_IO_EXTENT, DRV_NAME))
		return -ENODEV;

	/*
	 *	Read the station address PROM data from the special port.
	 */

	for (i = 0; i < 6; i++) {
		outw(i, ioaddr + EL1_DATAPTR);
		station_addr[i] = inb(ioaddr + EL1_SAPROM);
	}
	/*
	 *	Check the first three octets of the S.A. for 3Com's prefix, or
	 *	for the Sager NP943 prefix.
	 */

	if (station_addr[0] == 0x02 && station_addr[1] == 0x60 &&
	    station_addr[2] == 0x8c)
		mname = "3c501";
	else if (station_addr[0] == 0x00 && station_addr[1] == 0x80 &&
		 station_addr[2] == 0xC8)
		mname = "NP943";
	else {
		release_region(ioaddr, EL1_IO_EXTENT);
		return -ENODEV;
	}

	/*
	 *	We auto-IRQ by shutting off the interrupt line and letting it
	 *	float high.
	 */

	dev->irq = irq;

	if (dev->irq < 2) {
		unsigned long irq_mask;

		irq_mask = probe_irq_on();
		inb(RX_STATUS);		/* Clear pending interrupts. */
		inb(TX_STATUS);
		outb(AX_LOOP + 1, AX_CMD);

		outb(0x00, AX_CMD);

		mdelay(20);
		autoirq = probe_irq_off(irq_mask);

		if (autoirq == 0) {
			pr_warning("%s probe at %#x failed to detect IRQ line.\n",
				mname, ioaddr);
			release_region(ioaddr, EL1_IO_EXTENT);
			return -EAGAIN;
		}
	}

	outb(AX_RESET+AX_LOOP, AX_CMD);			/* Loopback mode. */
	dev->base_addr = ioaddr;
	memcpy(dev->dev_addr, station_addr, ETH_ALEN);

	if (mem_start & 0xf)
		el_debug = mem_start & 0x7;
	if (autoirq)
		dev->irq = autoirq;

	pr_info("%s: %s EtherLink at %#lx, using %sIRQ %d.\n",
			dev->name, mname, dev->base_addr,
			autoirq ? "auto":"assigned ", dev->irq);

#ifdef CONFIG_IP_MULTICAST
	pr_warning("WARNING: Use of the 3c501 in a multicast kernel is NOT recommended.\n");
#endif

	if (el_debug)
		pr_debug("%s", version);

	lp = netdev_priv(dev);
	memset(lp, 0, sizeof(struct net_local));
	spin_lock_init(&lp->lock);

	/*
	 *	The EL1-specific entries in the device structure.
	 */

	dev->netdev_ops = &el_netdev_ops;
	dev->watchdog_timeo = HZ;
	dev->ethtool_ops = &netdev_ethtool_ops;
	return 0;
}

/**
 *	el1_open:
 *	@dev: device that is being opened
 *
 *	When an ifconfig is issued which changes the device flags to include
 *	IFF_UP this function is called. It is only called when the change
 *	occurs, not when the interface remains up. #el1_close will be called
 *	when it goes down.
 *
 *	Returns 0 for a successful open, or -EAGAIN if someone has run off
 *	with our interrupt line.
 */

static int el_open(struct net_device *dev)
{
	int retval;
	int ioaddr = dev->base_addr;
	struct net_local *lp = netdev_priv(dev);
	unsigned long flags;

	if (el_debug > 2)
		pr_debug("%s: Doing el_open()...\n", dev->name);

	retval = request_irq(dev->irq, el_interrupt, 0, dev->name, dev);
	if (retval)
		return retval;

	spin_lock_irqsave(&lp->lock, flags);
	el_reset(dev);
	spin_unlock_irqrestore(&lp->lock, flags);

	lp->txing = 0;		/* Board in RX mode */
	outb(AX_RX, AX_CMD);	/* Aux control, irq and receive enabled */
	netif_start_queue(dev);
	return 0;
}

/**
 * el_timeout:
 * @dev: The 3c501 card that has timed out
 *
 * Attempt to restart the board. This is basically a mixture of extreme
 * violence and prayer
 *
 */

static void el_timeout(struct net_device *dev)
{
	struct net_local *lp = netdev_priv(dev);
	int ioaddr = dev->base_addr;

	if (el_debug)
		pr_debug("%s: transmit timed out, txsr %#2x axsr=%02x rxsr=%02x.\n",
			dev->name, inb(TX_STATUS),
			inb(AX_STATUS), inb(RX_STATUS));
	dev->stats.tx_errors++;
	outb(TX_NORM, TX_CMD);
	outb(RX_NORM, RX_CMD);
	outb(AX_OFF, AX_CMD);	/* Just trigger a false interrupt. */
	outb(AX_RX, AX_CMD);	/* Aux control, irq and receive enabled */
	lp->txing = 0;		/* Ripped back in to RX */
	netif_wake_queue(dev);
}


/**
 * el_start_xmit:
 * @skb: The packet that is queued to be sent
 * @dev: The 3c501 card we want to throw it down
 *
 * Attempt to send a packet to a 3c501 card. There are some interesting
 * catches here because the 3c501 is an extremely old and therefore
 * stupid piece of technology.
 *
 * If we are handling an interrupt on the other CPU we cannot load a packet
 * as we may still be attempting to retrieve the last RX packet buffer.
 *
 * When a transmit times out we dump the card into control mode and just
 * start again. It happens enough that it isn't worth logging.
 *
 * We avoid holding the spin locks when doing the packet load to the board.
 * The device is very slow, and its DMA mode is even slower. If we held the
 * lock while loading 1500 bytes onto the controller we would drop a lot of
 * serial port characters. This requires we do extra locking, but we have
 * no real choice.
 */

static netdev_tx_t el_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct net_local *lp = netdev_priv(dev);
	int ioaddr = dev->base_addr;
	unsigned long flags;

	/*
	 *	Avoid incoming interrupts between us flipping txing and flipping
	 *	mode as the driver assumes txing is a faithful indicator of card
	 *	state
	 */

	spin_lock_irqsave(&lp->lock, flags);

	/*
	 *	Avoid timer-based retransmission conflicts.
	 */

	netif_stop_queue(dev);

	do {
		int len = skb->len;
		int pad = 0;
		int gp_start;
		unsigned char *buf = skb->data;

		if (len < ETH_ZLEN)
			pad = ETH_ZLEN - len;

		gp_start = 0x800 - (len + pad);

		lp->tx_pkt_start = gp_start;
		lp->collisions = 0;

		dev->stats.tx_bytes += skb->len;

		/*
		 *	Command mode with status cleared should [in theory]
		 *	mean no more interrupts can be pending on the card.
		 */

		outb_p(AX_SYS, AX_CMD);
		inb_p(RX_STATUS);
		inb_p(TX_STATUS);

		lp->loading = 1;
		lp->txing = 1;

		/*
		 *	Turn interrupts back on while we spend a pleasant
		 *	afternoon loading bytes into the board
		 */

		spin_unlock_irqrestore(&lp->lock, flags);

		/* Set rx packet area to 0. */
		outw(0x00, RX_BUF_CLR);
		/* aim - packet will be loaded into buffer start */
		outw(gp_start, GP_LOW);
		/* load buffer (usual thing each byte increments the pointer) */
		outsb(DATAPORT, buf, len);
		if (pad) {
			while (pad--)		/* Zero fill buffer tail */
				outb(0, DATAPORT);
		}
		/* the board reuses the same register */
		outw(gp_start, GP_LOW);

		if (lp->loading != 2) {
			/* fire ... Trigger xmit.  */
			outb(AX_XMIT, AX_CMD);
			lp->loading = 0;
			if (el_debug > 2)
				pr_debug(" queued xmit.\n");
			dev_kfree_skb(skb);
			return NETDEV_TX_OK;
		}
		/* A receive upset our load, despite our best efforts */
		if (el_debug > 2)
			pr_debug("%s: burped during tx load.\n", dev->name);
		spin_lock_irqsave(&lp->lock, flags);
	} while (1);
}

/**
 * el_interrupt:
 * @irq: Interrupt number
 * @dev_id: The 3c501 that burped
 *
 * Handle the ether interface interrupts. The 3c501 needs a lot more
 * hand holding than most cards. In particular we get a transmit interrupt
 * with a collision error because the board firmware isn't capable of rewinding
 * its own transmit buffer pointers. It can however count to 16 for us.
 *
 * On the receive side the card is also very dumb. It has no buffering to
 * speak of. We simply pull the packet out of its PIO buffer (which is slow)
 * and queue it for the kernel. Then we reset the card for the next packet.
 *
 * We sometimes get surprise interrupts late both because the SMP IRQ delivery
 * is message passing and because the card sometimes seems to deliver late. I
 * think if it is part way through a receive and the mode is changed it carries
 * on receiving and sends us an interrupt. We have to band aid all these cases
 * to get a sensible 150kBytes/second performance. Even then you want a small
 * TCP window.
 */

static irqreturn_t el_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct net_local *lp;
	int ioaddr;
	int axsr;			/* Aux. status reg. */

	ioaddr = dev->base_addr;
	lp = netdev_priv(dev);

	spin_lock(&lp->lock);

	/*
	 *	What happened ?
	 */

	axsr = inb(AX_STATUS);

	/*
	 *	Log it
	 */

	if (el_debug > 3)
		pr_debug("%s: el_interrupt() aux=%#02x\n", dev->name, axsr);

	if (lp->loading == 1 && !lp->txing)
		pr_warning("%s: Inconsistent state loading while not in tx\n",
			dev->name);

	if (lp->txing) {
		/*
		 *	Board in transmit mode. May be loading. If we are
		 *	loading we shouldn't have got this.
		 */
		int txsr = inb(TX_STATUS);

		if (lp->loading == 1) {
			if (el_debug > 2)
				pr_debug("%s: Interrupt while loading [txsr=%02x gp=%04x rp=%04x]\n",
					dev->name, txsr, inw(GP_LOW), inw(RX_LOW));

			/* Force a reload */
			lp->loading = 2;
			spin_unlock(&lp->lock);
			goto out;
		}
		if (el_debug > 6)
			pr_debug("%s: txsr=%02x gp=%04x rp=%04x\n", dev->name,
					txsr, inw(GP_LOW), inw(RX_LOW));

		if ((axsr & 0x80) && (txsr & TX_READY) == 0) {
			/*
			 *	FIXME: is there a logic to whether to keep
			 *	on trying or reset immediately ?
			 */
			if (el_debug > 1)
				pr_debug("%s: Unusual interrupt during Tx, txsr=%02x axsr=%02x gp=%03x rp=%03x.\n",
					dev->name, txsr, axsr,
					inw(ioaddr + EL1_DATAPTR),
					inw(ioaddr + EL1_RXPTR));
			lp->txing = 0;
			netif_wake_queue(dev);
		} else if (txsr & TX_16COLLISIONS) {
			/*
			 *	Timed out
			 */
			if (el_debug)
				pr_debug("%s: Transmit failed 16 times, Ethernet jammed?\n", dev->name);
			outb(AX_SYS, AX_CMD);
			lp->txing = 0;
			dev->stats.tx_aborted_errors++;
			netif_wake_queue(dev);
		} else if (txsr & TX_COLLISION) {
			/*
			 *	Retrigger xmit.
			 */

			if (el_debug > 6)
				pr_debug("%s: retransmitting after a collision.\n", dev->name);
			/*
			 *	Poor little chip can't reset its own start
			 *	pointer
			 */

			outb(AX_SYS, AX_CMD);
			outw(lp->tx_pkt_start, GP_LOW);
			outb(AX_XMIT, AX_CMD);
			dev->stats.collisions++;
			spin_unlock(&lp->lock);
			goto out;
		} else {
			/*
			 *	It worked.. we will now fall through and receive
			 */
			dev->stats.tx_packets++;
			if (el_debug > 6)
				pr_debug("%s: Tx succeeded %s\n", dev->name,
					(txsr & TX_RDY) ? "." : "but tx is busy!");
			/*
			 *	This is safe the interrupt is atomic WRT itself.
			 */
			lp->txing = 0;
			/* In case more to transmit */
			netif_wake_queue(dev);
		}
	} else {
		/*
		 *	In receive mode.
		 */

		int rxsr = inb(RX_STATUS);
		if (el_debug > 5)
			pr_debug("%s: rxsr=%02x txsr=%02x rp=%04x\n",
				dev->name, rxsr, inb(TX_STATUS), inw(RX_LOW));
		/*
		 *	Just reading rx_status fixes most errors.
		 */
		if (rxsr & RX_MISSED)
			dev->stats.rx_missed_errors++;
		else if (rxsr & RX_RUNT) {
			/* Handled to avoid board lock-up. */
			dev->stats.rx_length_errors++;
			if (el_debug > 5)
				pr_debug("%s: runt.\n", dev->name);
		} else if (rxsr & RX_GOOD) {
			/*
			 *	Receive worked.
			 */
			el_receive(dev);
		} else {
			/*
			 *	Nothing?  Something is broken!
			 */
			if (el_debug > 2)
				pr_debug("%s: No packet seen, rxsr=%02x **resetting 3c501***\n",
					dev->name, rxsr);
			el_reset(dev);
		}
	}

	/*
	 *	Move into receive mode
	 */

	outb(AX_RX, AX_CMD);
	outw(0x00, RX_BUF_CLR);
	inb(RX_STATUS);		/* Be certain that interrupts are cleared. */
	inb(TX_STATUS);
	spin_unlock(&lp->lock);
out:
	return IRQ_HANDLED;
}


/**
 * el_receive:
 * @dev: Device to pull the packets from
 *
 * We have a good packet. Well, not really "good", just mostly not broken.
 * We must check everything to see if it is good. In particular we occasionally
 * get wild packet sizes from the card. If the packet seems sane we PIO it
 * off the card and queue it for the protocol layers.
 */

static void el_receive(struct net_device *dev)
{
	int ioaddr = dev->base_addr;
	int pkt_len;
	struct sk_buff *skb;

	pkt_len = inw(RX_LOW);

	if (el_debug > 4)
		pr_debug(" el_receive %d.\n", pkt_len);

	if (pkt_len < 60 || pkt_len > 1536) {
		if (el_debug)
			pr_debug("%s: bogus packet, length=%d\n",
						dev->name, pkt_len);
		dev->stats.rx_over_errors++;
		return;
	}

	/*
	 *	Command mode so we can empty the buffer
	 */

	outb(AX_SYS, AX_CMD);
	skb = dev_alloc_skb(pkt_len+2);

	/*
	 *	Start of frame
	 */

	outw(0x00, GP_LOW);
	if (skb == NULL) {
		pr_info("%s: Memory squeeze, dropping packet.\n", dev->name);
		dev->stats.rx_dropped++;
		return;
	} else {
		skb_reserve(skb, 2);	/* Force 16 byte alignment */
		/*
		 *	The read increments through the bytes. The interrupt
		 *	handler will fix the pointer when it returns to
		 *	receive mode.
		 */
		insb(DATAPORT, skb_put(skb, pkt_len), pkt_len);
		skb->protocol = eth_type_trans(skb, dev);
		netif_rx(skb);
		dev->stats.rx_packets++;
		dev->stats.rx_bytes += pkt_len;
	}
}

/**
 * el_reset: Reset a 3c501 card
 * @dev: The 3c501 card about to get zapped
 *
 * Even resetting a 3c501 isn't simple. When you activate reset it loses all
 * its configuration. You must hold the lock when doing this. The function
 * cannot take the lock itself as it is callable from the irq handler.
 */

static void  el_reset(struct net_device *dev)
{
	struct net_local *lp = netdev_priv(dev);
	int ioaddr = dev->base_addr;

	if (el_debug > 2)
		pr_info("3c501 reset...\n");
	outb(AX_RESET, AX_CMD);		/* Reset the chip */
	/* Aux control, irq and loopback enabled */
	outb(AX_LOOP, AX_CMD);
	{
		int i;
		for (i = 0; i < 6; i++)	/* Set the station address. */
			outb(dev->dev_addr[i], ioaddr + i);
	}

	outw(0, RX_BUF_CLR);		/* Set rx packet area to 0. */
	outb(TX_NORM, TX_CMD);		/* tx irq on done, collision */
	outb(RX_NORM, RX_CMD);		/* Set Rx commands. */
	inb(RX_STATUS);			/* Clear status. */
	inb(TX_STATUS);
	lp->txing = 0;
}

/**
 * el1_close:
 * @dev: 3c501 card to shut down
 *
 * Close a 3c501 card. The IFF_UP flag has been cleared by the user via
 * the SIOCSIFFLAGS ioctl. We stop any further transmissions being queued,
 * and then disable the interrupts. Finally we reset the chip. The effects
 * of the rest will be cleaned up by #el1_open. Always returns 0 indicating
 * a success.
 */

static int el1_close(struct net_device *dev)
{
	int ioaddr = dev->base_addr;

	if (el_debug > 2)
		pr_info("%s: Shutting down Ethernet card at %#x.\n",
						dev->name, ioaddr);

	netif_stop_queue(dev);

	/*
	 *	Free and disable the IRQ.
	 */

	free_irq(dev->irq, dev);
	outb(AX_RESET, AX_CMD);		/* Reset the chip */

	return 0;
}

/**
 * set_multicast_list:
 * @dev: The device to adjust
 *
 * Set or clear the multicast filter for this adaptor to use the best-effort
 * filtering supported. The 3c501 supports only three modes of filtering.
 * It always receives broadcasts and packets for itself. You can choose to
 * optionally receive all packets, or all multicast packets on top of this.
 */

static void set_multicast_list(struct net_device *dev)
{
	int ioaddr = dev->base_addr;

	if (dev->flags & IFF_PROMISC) {
		outb(RX_PROM, RX_CMD);
		inb(RX_STATUS);
	} else if (!netdev_mc_empty(dev) || dev->flags & IFF_ALLMULTI) {
		/* Multicast or all multicast is the same */
		outb(RX_MULT, RX_CMD);
		inb(RX_STATUS);		/* Clear status. */
	} else {
		outb(RX_NORM, RX_CMD);
		inb(RX_STATUS);
	}
}


static void netdev_get_drvinfo(struct net_device *dev,
			       struct ethtool_drvinfo *info)
{
	strcpy(info->driver, DRV_NAME);
	strcpy(info->version, DRV_VERSION);
	sprintf(info->bus_info, "ISA 0x%lx", dev->base_addr);
}

static u32 netdev_get_msglevel(struct net_device *dev)
{
	return debug;
}

static void netdev_set_msglevel(struct net_device *dev, u32 level)
{
	debug = level;
}

static const struct ethtool_ops netdev_ethtool_ops = {
	.get_drvinfo		= netdev_get_drvinfo,
	.get_msglevel		= netdev_get_msglevel,
	.set_msglevel		= netdev_set_msglevel,
};

#ifdef MODULE

static struct net_device *dev_3c501;

module_param(io, int, 0);
module_param(irq, int, 0);
MODULE_PARM_DESC(io, "EtherLink I/O base address");
MODULE_PARM_DESC(irq, "EtherLink IRQ number");

/**
 * init_module:
 *
 * When the driver is loaded as a module this function is called. We fake up
 * a device structure with the base I/O and interrupt set as if it were being
 * called from Space.c. This minimises the extra code that would otherwise
 * be required.
 *
 * Returns 0 for success or -EIO if a card is not found. Returning an error
 * here also causes the module to be unloaded
 */

int __init init_module(void)
{
	dev_3c501 = el1_probe(-1);
	if (IS_ERR(dev_3c501))
		return PTR_ERR(dev_3c501);
	return 0;
}

/**
 * cleanup_module:
 *
 * The module is being unloaded. We unhook our network device from the system
 * and then free up the resources we took when the card was found.
 */

void __exit cleanup_module(void)
{
	struct net_device *dev = dev_3c501;
	unregister_netdev(dev);
	release_region(dev->base_addr, EL1_IO_EXTENT);
	free_netdev(dev);
}

#endif /* MODULE */

MODULE_AUTHOR("Donald Becker, Alan Cox");
MODULE_DESCRIPTION("Support for the ancient 3Com 3c501 ethernet card");
MODULE_LICENSE("GPL");