xref: /linux/drivers/net/ethernet/realtek/atp.c (revision da1d9caf95def6f0320819cf941c9fd1069ba9e1)
1 /* atp.c: Attached (pocket) ethernet adapter driver for linux. */
2 /*
3 	This is a driver for commonly OEM pocket (parallel port)
4 	ethernet adapters based on the Realtek RTL8002 and RTL8012 chips.
5 
6 	Written 1993-2000 by Donald Becker.
7 
8 	This software may be used and distributed according to the terms of
9 	the GNU General Public License (GPL), incorporated herein by reference.
10 	Drivers based on or derived from this code fall under the GPL and must
11 	retain the authorship, copyright and license notice.  This file is not
12 	a complete program and may only be used when the entire operating
13 	system is licensed under the GPL.
14 
15 	Copyright 1993 United States Government as represented by the Director,
16 	National Security Agency.  Copyright 1994-2000 retained by the original
17 	author, Donald Becker. The timer-based reset code was supplied in 1995
18 	by Bill Carlson, wwc@super.org.
19 
20 	The author may be reached as becker@scyld.com, or C/O
21 	Scyld Computing Corporation
22 	410 Severn Ave., Suite 210
23 	Annapolis MD 21403
24 
25 	Support information and updates available at
26 	http://www.scyld.com/network/atp.html
27 
28 
29 	Modular support/softnet added by Alan Cox.
30 	_bit abuse fixed up by Alan Cox
31 
32 */
33 
34 static const char version[] =
35 "atp.c:v1.09=ac 2002/10/01 Donald Becker <becker@scyld.com>\n";
36 
37 /* The user-configurable values.
38    These may be modified when a driver module is loaded.*/
39 
40 static int debug = 1; 			/* 1 normal messages, 0 quiet .. 7 verbose. */
41 #define net_debug debug
42 
43 /* Maximum events (Rx packets, etc.) to handle at each interrupt. */
44 static int max_interrupt_work = 15;
45 
46 #define NUM_UNITS 2
47 /* The standard set of ISA module parameters. */
48 static int io[NUM_UNITS];
49 static int irq[NUM_UNITS];
50 static int xcvr[NUM_UNITS]; 			/* The data transfer mode. */
51 
52 /* Operational parameters that are set at compile time. */
53 
54 /* Time in jiffies before concluding the transmitter is hung. */
55 #define TX_TIMEOUT  (400*HZ/1000)
56 
57 /*
58 	This file is a device driver for the RealTek (aka AT-Lan-Tec) pocket
59 	ethernet adapter.  This is a common low-cost OEM pocket ethernet
60 	adapter, sold under many names.
61 
62   Sources:
63 	This driver was written from the packet driver assembly code provided by
64 	Vincent Bono of AT-Lan-Tec.	 Ever try to figure out how a complicated
65 	device works just from the assembly code?  It ain't pretty.  The following
66 	description is written based on guesses and writing lots of special-purpose
67 	code to test my theorized operation.
68 
69 	In 1997 Realtek made available the documentation for the second generation
70 	RTL8012 chip, which has lead to several driver improvements.
71 	  http://www.realtek.com.tw/
72 
73 					Theory of Operation
74 
75 	The RTL8002 adapter seems to be built around a custom spin of the SEEQ
76 	controller core.  It probably has a 16K or 64K internal packet buffer, of
77 	which the first 4K is devoted to transmit and the rest to receive.
78 	The controller maintains the queue of received packet and the packet buffer
79 	access pointer internally, with only 'reset to beginning' and 'skip to next
80 	packet' commands visible.  The transmit packet queue holds two (or more?)
81 	packets: both 'retransmit this packet' (due to collision) and 'transmit next
82 	packet' commands must be started by hand.
83 
84 	The station address is stored in a standard bit-serial EEPROM which must be
85 	read (ughh) by the device driver.  (Provisions have been made for
86 	substituting a 74S288 PROM, but I haven't gotten reports of any models
87 	using it.)  Unlike built-in devices, a pocket adapter can temporarily lose
88 	power without indication to the device driver.  The major effect is that
89 	the station address, receive filter (promiscuous, etc.) and transceiver
90 	must be reset.
91 
92 	The controller itself has 16 registers, some of which use only the lower
93 	bits.  The registers are read and written 4 bits at a time.  The four bit
94 	register address is presented on the data lines along with a few additional
95 	timing and control bits.  The data is then read from status port or written
96 	to the data port.
97 
98 	Correction: the controller has two banks of 16 registers.  The second
99 	bank contains only the multicast filter table (now used) and the EEPROM
100 	access registers.
101 
102 	Since the bulk data transfer of the actual packets through the slow
103 	parallel port dominates the driver's running time, four distinct data
104 	(non-register) transfer modes are provided by the adapter, two in each
105 	direction.  In the first mode timing for the nibble transfers is
106 	provided through the data port.  In the second mode the same timing is
107 	provided through the control port.  In either case the data is read from
108 	the status port and written to the data port, just as it is accessing
109 	registers.
110 
111 	In addition to the basic data transfer methods, several more are modes are
112 	created by adding some delay by doing multiple reads of the data to allow
113 	it to stabilize.  This delay seems to be needed on most machines.
114 
115 	The data transfer mode is stored in the 'dev->if_port' field.  Its default
116 	value is '4'.  It may be overridden at boot-time using the third parameter
117 	to the "ether=..." initialization.
118 
119 	The header file <atp.h> provides inline functions that encapsulate the
120 	register and data access methods.  These functions are hand-tuned to
121 	generate reasonable object code.  This header file also documents my
122 	interpretations of the device registers.
123 */
124 
125 #include <linux/kernel.h>
126 #include <linux/module.h>
127 #include <linux/types.h>
128 #include <linux/fcntl.h>
129 #include <linux/interrupt.h>
130 #include <linux/ioport.h>
131 #include <linux/in.h>
132 #include <linux/string.h>
133 #include <linux/errno.h>
134 #include <linux/init.h>
135 #include <linux/crc32.h>
136 #include <linux/netdevice.h>
137 #include <linux/etherdevice.h>
138 #include <linux/skbuff.h>
139 #include <linux/spinlock.h>
140 #include <linux/delay.h>
141 #include <linux/bitops.h>
142 
143 #include <asm/io.h>
144 #include <asm/dma.h>
145 
146 #include "atp.h"
147 
148 MODULE_AUTHOR("Donald Becker <becker@scyld.com>");
149 MODULE_DESCRIPTION("RealTek RTL8002/8012 parallel port Ethernet driver");
150 MODULE_LICENSE("GPL");
151 
152 module_param(max_interrupt_work, int, 0);
153 module_param(debug, int, 0);
154 module_param_hw_array(io, int, ioport, NULL, 0);
155 module_param_hw_array(irq, int, irq, NULL, 0);
156 module_param_array(xcvr, int, NULL, 0);
157 MODULE_PARM_DESC(max_interrupt_work, "ATP maximum events handled per interrupt");
158 MODULE_PARM_DESC(debug, "ATP debug level (0-7)");
159 MODULE_PARM_DESC(io, "ATP I/O base address(es)");
160 MODULE_PARM_DESC(irq, "ATP IRQ number(s)");
161 MODULE_PARM_DESC(xcvr, "ATP transceiver(s) (0=internal, 1=external)");
162 
163 /* The number of low I/O ports used by the ethercard. */
164 #define ETHERCARD_TOTAL_SIZE	3
165 
166 /* Sequence to switch an 8012 from printer mux to ethernet mode. */
167 static char mux_8012[] = { 0xff, 0xf7, 0xff, 0xfb, 0xf3, 0xfb, 0xff, 0xf7,};
168 
169 struct net_local {
170     spinlock_t lock;
171     struct net_device *next_module;
172     struct timer_list timer;	/* Media selection timer. */
173     struct net_device *dev;	/* Timer dev. */
174     unsigned long last_rx_time;	/* Last Rx, in jiffies, to handle Rx hang. */
175     int saved_tx_size;
176     unsigned int tx_unit_busy:1;
177     unsigned char re_tx,	/* Number of packet retransmissions. */
178 		addr_mode,		/* Current Rx filter e.g. promiscuous, etc. */
179 		pac_cnt_in_tx_buf;
180 };
181 
182 /* This code, written by wwc@super.org, resets the adapter every
183    TIMED_CHECKER ticks.  This recovers from an unknown error which
184    hangs the device. */
185 #define TIMED_CHECKER (HZ/4)
186 #ifdef TIMED_CHECKER
187 #include <linux/timer.h>
188 static void atp_timed_checker(struct timer_list *t);
189 #endif
190 
191 /* Index to functions, as function prototypes. */
192 
193 static int atp_probe1(long ioaddr);
194 static void get_node_ID(struct net_device *dev);
195 static unsigned short eeprom_op(long ioaddr, unsigned int cmd);
196 static int net_open(struct net_device *dev);
197 static void hardware_init(struct net_device *dev);
198 static void write_packet(long ioaddr, int length, unsigned char *packet, int pad, int mode);
199 static void trigger_send(long ioaddr, int length);
200 static netdev_tx_t atp_send_packet(struct sk_buff *skb,
201 				   struct net_device *dev);
202 static irqreturn_t atp_interrupt(int irq, void *dev_id);
203 static void net_rx(struct net_device *dev);
204 static void read_block(long ioaddr, int length, unsigned char *buffer, int data_mode);
205 static int net_close(struct net_device *dev);
206 static void set_rx_mode(struct net_device *dev);
207 static void tx_timeout(struct net_device *dev, unsigned int txqueue);
208 
209 
210 /* A list of all installed ATP devices, for removing the driver module. */
211 static struct net_device *root_atp_dev;
212 
213 /* Check for a network adapter of this type, and return '0' iff one exists.
214    If dev->base_addr == 0, probe all likely locations.
215    If dev->base_addr == 1, always return failure.
216    If dev->base_addr == 2, allocate space for the device and return success
217    (detachable devices only).
218 
219    FIXME: we should use the parport layer for this
220    */
221 static int __init atp_init(void)
222 {
223 	int *port, ports[] = {0x378, 0x278, 0x3bc, 0};
224 	int base_addr = io[0];
225 
226 	if (base_addr > 0x1ff)		/* Check a single specified location. */
227 		return atp_probe1(base_addr);
228 	else if (base_addr == 1)	/* Don't probe at all. */
229 		return -ENXIO;
230 
231 	for (port = ports; *port; port++) {
232 		long ioaddr = *port;
233 		outb(0x57, ioaddr + PAR_DATA);
234 		if (inb(ioaddr + PAR_DATA) != 0x57)
235 			continue;
236 		if (atp_probe1(ioaddr) == 0)
237 			return 0;
238 	}
239 
240 	return -ENODEV;
241 }
242 
243 static const struct net_device_ops atp_netdev_ops = {
244 	.ndo_open		= net_open,
245 	.ndo_stop		= net_close,
246 	.ndo_start_xmit		= atp_send_packet,
247 	.ndo_set_rx_mode	= set_rx_mode,
248 	.ndo_tx_timeout		= tx_timeout,
249 	.ndo_set_mac_address 	= eth_mac_addr,
250 	.ndo_validate_addr	= eth_validate_addr,
251 };
252 
253 static int __init atp_probe1(long ioaddr)
254 {
255 	struct net_device *dev = NULL;
256 	struct net_local *lp;
257 	int saved_ctrl_reg, status, i;
258 	int res;
259 
260 	outb(0xff, ioaddr + PAR_DATA);
261 	/* Save the original value of the Control register, in case we guessed
262 	   wrong. */
263 	saved_ctrl_reg = inb(ioaddr + PAR_CONTROL);
264 	if (net_debug > 3)
265 		printk("atp: Control register was %#2.2x.\n", saved_ctrl_reg);
266 	/* IRQEN=0, SLCTB=high INITB=high, AUTOFDB=high, STBB=high. */
267 	outb(0x04, ioaddr + PAR_CONTROL);
268 #ifndef final_version
269 	if (net_debug > 3) {
270 		/* Turn off the printer multiplexer on the 8012. */
271 		for (i = 0; i < 8; i++)
272 			outb(mux_8012[i], ioaddr + PAR_DATA);
273 		write_reg(ioaddr, MODSEL, 0x00);
274 		printk("atp: Registers are ");
275 		for (i = 0; i < 32; i++)
276 			printk(" %2.2x", read_nibble(ioaddr, i));
277 		printk(".\n");
278 	}
279 #endif
280 	/* Turn off the printer multiplexer on the 8012. */
281 	for (i = 0; i < 8; i++)
282 		outb(mux_8012[i], ioaddr + PAR_DATA);
283 	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
284 	/* udelay() here? */
285 	status = read_nibble(ioaddr, CMR1);
286 
287 	if (net_debug > 3) {
288 		printk(KERN_DEBUG "atp: Status nibble was %#2.2x..", status);
289 		for (i = 0; i < 32; i++)
290 			printk(" %2.2x", read_nibble(ioaddr, i));
291 		printk("\n");
292 	}
293 
294 	if ((status & 0x78) != 0x08) {
295 		/* The pocket adapter probe failed, restore the control register. */
296 		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
297 		return -ENODEV;
298 	}
299 	status = read_nibble(ioaddr, CMR2_h);
300 	if ((status & 0x78) != 0x10) {
301 		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
302 		return -ENODEV;
303 	}
304 
305 	dev = alloc_etherdev(sizeof(struct net_local));
306 	if (!dev)
307 		return -ENOMEM;
308 
309 	/* Find the IRQ used by triggering an interrupt. */
310 	write_reg_byte(ioaddr, CMR2, 0x01);			/* No accept mode, IRQ out. */
311 	write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);	/* Enable Tx and Rx. */
312 
313 	/* Omit autoIRQ routine for now. Use "table lookup" instead.  Uhgggh. */
314 	if (irq[0])
315 		dev->irq = irq[0];
316 	else if (ioaddr == 0x378)
317 		dev->irq = 7;
318 	else
319 		dev->irq = 5;
320 	write_reg_high(ioaddr, CMR1, CMR1h_TxRxOFF); /* Disable Tx and Rx units. */
321 	write_reg(ioaddr, CMR2, CMR2_NULL);
322 
323 	dev->base_addr = ioaddr;
324 
325 	/* Read the station address PROM.  */
326 	get_node_ID(dev);
327 
328 #ifndef MODULE
329 	if (net_debug)
330 		printk(KERN_INFO "%s", version);
331 #endif
332 
333 	printk(KERN_NOTICE "%s: Pocket adapter found at %#3lx, IRQ %d, "
334 	       "SAPROM %pM.\n",
335 	       dev->name, dev->base_addr, dev->irq, dev->dev_addr);
336 
337 	/* Reset the ethernet hardware and activate the printer pass-through. */
338 	write_reg_high(ioaddr, CMR1, CMR1h_RESET | CMR1h_MUX);
339 
340 	lp = netdev_priv(dev);
341 	lp->addr_mode = CMR2h_Normal;
342 	spin_lock_init(&lp->lock);
343 
344 	/* For the ATP adapter the "if_port" is really the data transfer mode. */
345 	if (xcvr[0])
346 		dev->if_port = xcvr[0];
347 	else
348 		dev->if_port = (dev->mem_start & 0xf) ? (dev->mem_start & 0x7) : 4;
349 	if (dev->mem_end & 0xf)
350 		net_debug = dev->mem_end & 7;
351 
352 	dev->netdev_ops 	= &atp_netdev_ops;
353 	dev->watchdog_timeo	= TX_TIMEOUT;
354 
355 	res = register_netdev(dev);
356 	if (res) {
357 		free_netdev(dev);
358 		return res;
359 	}
360 
361 	lp->next_module = root_atp_dev;
362 	root_atp_dev = dev;
363 
364 	return 0;
365 }
366 
367 /* Read the station address PROM, usually a word-wide EEPROM. */
368 static void __init get_node_ID(struct net_device *dev)
369 {
370 	long ioaddr = dev->base_addr;
371 	__be16 addr[ETH_ALEN / 2];
372 	int sa_offset = 0;
373 	int i;
374 
375 	write_reg(ioaddr, CMR2, CMR2_EEPROM);	  /* Point to the EEPROM control registers. */
376 
377 	/* Some adapters have the station address at offset 15 instead of offset
378 	   zero.  Check for it, and fix it if needed. */
379 	if (eeprom_op(ioaddr, EE_READ(0)) == 0xffff)
380 		sa_offset = 15;
381 
382 	for (i = 0; i < 3; i++)
383 		addr[i] =
384 			cpu_to_be16(eeprom_op(ioaddr, EE_READ(sa_offset + i)));
385 	eth_hw_addr_set(dev, (u8 *)addr);
386 
387 	write_reg(ioaddr, CMR2, CMR2_NULL);
388 }
389 
390 /*
391   An EEPROM read command starts by shifting out 0x60+address, and then
392   shifting in the serial data. See the NatSemi databook for details.
393  *		   ________________
394  * CS : __|
395  *			   ___	   ___
396  * CLK: ______|	  |___|	  |
397  *		 __ _______ _______
398  * DI :	 __X_______X_______X
399  * DO :	 _________X_______X
400  */
401 
402 static unsigned short __init eeprom_op(long ioaddr, u32 cmd)
403 {
404 	unsigned eedata_out = 0;
405 	int num_bits = EE_CMD_SIZE;
406 
407 	while (--num_bits >= 0) {
408 		char outval = (cmd & (1<<num_bits)) ? EE_DATA_WRITE : 0;
409 		write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_LOW);
410 		write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_HIGH);
411 		eedata_out <<= 1;
412 		if (read_nibble(ioaddr, PROM_DATA) & EE_DATA_READ)
413 			eedata_out++;
414 	}
415 	write_reg_high(ioaddr, PROM_CMD, EE_CLK_LOW & ~EE_CS);
416 	return eedata_out;
417 }
418 
419 
420 /* Open/initialize the board.  This is called (in the current kernel)
421    sometime after booting when the 'ifconfig' program is run.
422 
423    This routine sets everything up anew at each open, even
424    registers that "should" only need to be set once at boot, so that
425    there is non-reboot way to recover if something goes wrong.
426 
427    This is an attachable device: if there is no private entry then it wasn't
428    probed for at boot-time, and we need to probe for it again.
429    */
430 static int net_open(struct net_device *dev)
431 {
432 	struct net_local *lp = netdev_priv(dev);
433 	int ret;
434 
435 	/* The interrupt line is turned off (tri-stated) when the device isn't in
436 	   use.  That's especially important for "attached" interfaces where the
437 	   port or interrupt may be shared. */
438 	ret = request_irq(dev->irq, atp_interrupt, 0, dev->name, dev);
439 	if (ret)
440 		return ret;
441 
442 	hardware_init(dev);
443 
444 	lp->dev = dev;
445 	timer_setup(&lp->timer, atp_timed_checker, 0);
446 	lp->timer.expires = jiffies + TIMED_CHECKER;
447 	add_timer(&lp->timer);
448 
449 	netif_start_queue(dev);
450 	return 0;
451 }
452 
453 /* This routine resets the hardware.  We initialize everything, assuming that
454    the hardware may have been temporarily detached. */
455 static void hardware_init(struct net_device *dev)
456 {
457 	struct net_local *lp = netdev_priv(dev);
458 	long ioaddr = dev->base_addr;
459 	int i;
460 
461 	/* Turn off the printer multiplexer on the 8012. */
462 	for (i = 0; i < 8; i++)
463 		outb(mux_8012[i], ioaddr + PAR_DATA);
464 	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
465 
466 	for (i = 0; i < 6; i++)
467 		write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);
468 
469 	write_reg_high(ioaddr, CMR2, lp->addr_mode);
470 
471 	if (net_debug > 2) {
472 		printk(KERN_DEBUG "%s: Reset: current Rx mode %d.\n", dev->name,
473 			   (read_nibble(ioaddr, CMR2_h) >> 3) & 0x0f);
474 	}
475 
476 	write_reg(ioaddr, CMR2, CMR2_IRQOUT);
477 	write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);
478 
479 	/* Enable the interrupt line from the serial port. */
480 	outb(Ctrl_SelData + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
481 
482 	/* Unmask the interesting interrupts. */
483 	write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);
484 	write_reg_high(ioaddr, IMR, ISRh_RxErr);
485 
486 	lp->tx_unit_busy = 0;
487 	lp->pac_cnt_in_tx_buf = 0;
488 	lp->saved_tx_size = 0;
489 }
490 
491 static void trigger_send(long ioaddr, int length)
492 {
493 	write_reg_byte(ioaddr, TxCNT0, length & 0xff);
494 	write_reg(ioaddr, TxCNT1, length >> 8);
495 	write_reg(ioaddr, CMR1, CMR1_Xmit);
496 }
497 
498 static void write_packet(long ioaddr, int length, unsigned char *packet, int pad_len, int data_mode)
499 {
500     if (length & 1)
501     {
502 	length++;
503 	pad_len++;
504     }
505 
506     outb(EOC+MAR, ioaddr + PAR_DATA);
507     if ((data_mode & 1) == 0) {
508 		/* Write the packet out, starting with the write addr. */
509 		outb(WrAddr+MAR, ioaddr + PAR_DATA);
510 		do {
511 			write_byte_mode0(ioaddr, *packet++);
512 		} while (--length > pad_len) ;
513 		do {
514 			write_byte_mode0(ioaddr, 0);
515 		} while (--length > 0) ;
516     } else {
517 		/* Write the packet out in slow mode. */
518 		unsigned char outbyte = *packet++;
519 
520 		outb(Ctrl_LNibWrite + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
521 		outb(WrAddr+MAR, ioaddr + PAR_DATA);
522 
523 		outb((outbyte & 0x0f)|0x40, ioaddr + PAR_DATA);
524 		outb(outbyte & 0x0f, ioaddr + PAR_DATA);
525 		outbyte >>= 4;
526 		outb(outbyte & 0x0f, ioaddr + PAR_DATA);
527 		outb(Ctrl_HNibWrite + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
528 		while (--length > pad_len)
529 			write_byte_mode1(ioaddr, *packet++);
530 		while (--length > 0)
531 			write_byte_mode1(ioaddr, 0);
532     }
533     /* Terminate the Tx frame.  End of write: ECB. */
534     outb(0xff, ioaddr + PAR_DATA);
535     outb(Ctrl_HNibWrite | Ctrl_SelData | Ctrl_IRQEN, ioaddr + PAR_CONTROL);
536 }
537 
538 static void tx_timeout(struct net_device *dev, unsigned int txqueue)
539 {
540 	long ioaddr = dev->base_addr;
541 
542 	printk(KERN_WARNING "%s: Transmit timed out, %s?\n", dev->name,
543 		   inb(ioaddr + PAR_CONTROL) & 0x10 ? "network cable problem"
544 		   :  "IRQ conflict");
545 	dev->stats.tx_errors++;
546 	/* Try to restart the adapter. */
547 	hardware_init(dev);
548 	netif_trans_update(dev); /* prevent tx timeout */
549 	netif_wake_queue(dev);
550 	dev->stats.tx_errors++;
551 }
552 
553 static netdev_tx_t atp_send_packet(struct sk_buff *skb,
554 				   struct net_device *dev)
555 {
556 	struct net_local *lp = netdev_priv(dev);
557 	long ioaddr = dev->base_addr;
558 	int length;
559 	unsigned long flags;
560 
561 	length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;
562 
563 	netif_stop_queue(dev);
564 
565 	/* Disable interrupts by writing 0x00 to the Interrupt Mask Register.
566 	   This sequence must not be interrupted by an incoming packet. */
567 
568 	spin_lock_irqsave(&lp->lock, flags);
569 	write_reg(ioaddr, IMR, 0);
570 	write_reg_high(ioaddr, IMR, 0);
571 	spin_unlock_irqrestore(&lp->lock, flags);
572 
573 	write_packet(ioaddr, length, skb->data, length-skb->len, dev->if_port);
574 
575 	lp->pac_cnt_in_tx_buf++;
576 	if (lp->tx_unit_busy == 0) {
577 		trigger_send(ioaddr, length);
578 		lp->saved_tx_size = 0; 				/* Redundant */
579 		lp->re_tx = 0;
580 		lp->tx_unit_busy = 1;
581 	} else
582 		lp->saved_tx_size = length;
583 	/* Re-enable the LPT interrupts. */
584 	write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);
585 	write_reg_high(ioaddr, IMR, ISRh_RxErr);
586 
587 	dev_kfree_skb (skb);
588 	return NETDEV_TX_OK;
589 }
590 
591 
592 /* The typical workload of the driver:
593    Handle the network interface interrupts. */
594 static irqreturn_t atp_interrupt(int irq, void *dev_instance)
595 {
596 	struct net_device *dev = dev_instance;
597 	struct net_local *lp;
598 	long ioaddr;
599 	static int num_tx_since_rx;
600 	int boguscount = max_interrupt_work;
601 	int handled = 0;
602 
603 	ioaddr = dev->base_addr;
604 	lp = netdev_priv(dev);
605 
606 	spin_lock(&lp->lock);
607 
608 	/* Disable additional spurious interrupts. */
609 	outb(Ctrl_SelData, ioaddr + PAR_CONTROL);
610 
611 	/* The adapter's output is currently the IRQ line, switch it to data. */
612 	write_reg(ioaddr, CMR2, CMR2_NULL);
613 	write_reg(ioaddr, IMR, 0);
614 
615 	if (net_debug > 5)
616 		printk(KERN_DEBUG "%s: In interrupt ", dev->name);
617 	while (--boguscount > 0) {
618 		int status = read_nibble(ioaddr, ISR);
619 		if (net_debug > 5)
620 			printk("loop status %02x..", status);
621 
622 		if (status & (ISR_RxOK<<3)) {
623 			handled = 1;
624 			write_reg(ioaddr, ISR, ISR_RxOK); /* Clear the Rx interrupt. */
625 			do {
626 				int read_status = read_nibble(ioaddr, CMR1);
627 				if (net_debug > 6)
628 					printk("handling Rx packet %02x..", read_status);
629 				/* We acknowledged the normal Rx interrupt, so if the interrupt
630 				   is still outstanding we must have a Rx error. */
631 				if (read_status & (CMR1_IRQ << 3)) { /* Overrun. */
632 					dev->stats.rx_over_errors++;
633 					/* Set to no-accept mode long enough to remove a packet. */
634 					write_reg_high(ioaddr, CMR2, CMR2h_OFF);
635 					net_rx(dev);
636 					/* Clear the interrupt and return to normal Rx mode. */
637 					write_reg_high(ioaddr, ISR, ISRh_RxErr);
638 					write_reg_high(ioaddr, CMR2, lp->addr_mode);
639 				} else if ((read_status & (CMR1_BufEnb << 3)) == 0) {
640 					net_rx(dev);
641 					num_tx_since_rx = 0;
642 				} else
643 					break;
644 			} while (--boguscount > 0);
645 		} else if (status & ((ISR_TxErr + ISR_TxOK)<<3)) {
646 			handled = 1;
647 			if (net_debug > 6)
648 				printk("handling Tx done..");
649 			/* Clear the Tx interrupt.  We should check for too many failures
650 			   and reinitialize the adapter. */
651 			write_reg(ioaddr, ISR, ISR_TxErr + ISR_TxOK);
652 			if (status & (ISR_TxErr<<3)) {
653 				dev->stats.collisions++;
654 				if (++lp->re_tx > 15) {
655 					dev->stats.tx_aborted_errors++;
656 					hardware_init(dev);
657 					break;
658 				}
659 				/* Attempt to retransmit. */
660 				if (net_debug > 6)  printk("attempting to ReTx");
661 				write_reg(ioaddr, CMR1, CMR1_ReXmit + CMR1_Xmit);
662 			} else {
663 				/* Finish up the transmit. */
664 				dev->stats.tx_packets++;
665 				lp->pac_cnt_in_tx_buf--;
666 				if ( lp->saved_tx_size) {
667 					trigger_send(ioaddr, lp->saved_tx_size);
668 					lp->saved_tx_size = 0;
669 					lp->re_tx = 0;
670 				} else
671 					lp->tx_unit_busy = 0;
672 				netif_wake_queue(dev);	/* Inform upper layers. */
673 			}
674 			num_tx_since_rx++;
675 		} else if (num_tx_since_rx > 8 &&
676 			   time_after(jiffies, lp->last_rx_time + HZ)) {
677 			if (net_debug > 2)
678 				printk(KERN_DEBUG "%s: Missed packet? No Rx after %d Tx and "
679 					   "%ld jiffies status %02x  CMR1 %02x.\n", dev->name,
680 					   num_tx_since_rx, jiffies - lp->last_rx_time, status,
681 					   (read_nibble(ioaddr, CMR1) >> 3) & 15);
682 			dev->stats.rx_missed_errors++;
683 			hardware_init(dev);
684 			num_tx_since_rx = 0;
685 			break;
686 		} else
687 			break;
688 	}
689 
690 	/* This following code fixes a rare (and very difficult to track down)
691 	   problem where the adapter forgets its ethernet address. */
692 	{
693 		int i;
694 		for (i = 0; i < 6; i++)
695 			write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);
696 #if 0 && defined(TIMED_CHECKER)
697 		mod_timer(&lp->timer, jiffies + TIMED_CHECKER);
698 #endif
699 	}
700 
701 	/* Tell the adapter that it can go back to using the output line as IRQ. */
702 	write_reg(ioaddr, CMR2, CMR2_IRQOUT);
703 	/* Enable the physical interrupt line, which is sure to be low until.. */
704 	outb(Ctrl_SelData + Ctrl_IRQEN, ioaddr + PAR_CONTROL);
705 	/* .. we enable the interrupt sources. */
706 	write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);
707 	write_reg_high(ioaddr, IMR, ISRh_RxErr); 			/* Hmmm, really needed? */
708 
709 	spin_unlock(&lp->lock);
710 
711 	if (net_debug > 5) printk("exiting interrupt.\n");
712 	return IRQ_RETVAL(handled);
713 }
714 
715 #ifdef TIMED_CHECKER
716 /* This following code fixes a rare (and very difficult to track down)
717    problem where the adapter forgets its ethernet address. */
718 static void atp_timed_checker(struct timer_list *t)
719 {
720 	struct net_local *lp = from_timer(lp, t, timer);
721 	struct net_device *dev = lp->dev;
722 	long ioaddr = dev->base_addr;
723 	int tickssofar = jiffies - lp->last_rx_time;
724 	int i;
725 
726 	spin_lock(&lp->lock);
727 	if (tickssofar > 2*HZ) {
728 #if 1
729 		for (i = 0; i < 6; i++)
730 			write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);
731 		lp->last_rx_time = jiffies;
732 #else
733 		for (i = 0; i < 6; i++)
734 			if (read_cmd_byte(ioaddr, PAR0 + i) != atp_timed_dev->dev_addr[i])
735 				{
736 			struct net_local *lp = netdev_priv(atp_timed_dev);
737 			write_reg_byte(ioaddr, PAR0 + i, atp_timed_dev->dev_addr[i]);
738 			if (i == 2)
739 			  dev->stats.tx_errors++;
740 			else if (i == 3)
741 			  dev->stats.tx_dropped++;
742 			else if (i == 4)
743 			  dev->stats.collisions++;
744 			else
745 			  dev->stats.rx_errors++;
746 		  }
747 #endif
748 	}
749 	spin_unlock(&lp->lock);
750 	lp->timer.expires = jiffies + TIMED_CHECKER;
751 	add_timer(&lp->timer);
752 }
753 #endif
754 
755 /* We have a good packet(s), get it/them out of the buffers. */
756 static void net_rx(struct net_device *dev)
757 {
758 	struct net_local *lp = netdev_priv(dev);
759 	long ioaddr = dev->base_addr;
760 	struct rx_header rx_head;
761 
762 	/* Process the received packet. */
763 	outb(EOC+MAR, ioaddr + PAR_DATA);
764 	read_block(ioaddr, 8, (unsigned char*)&rx_head, dev->if_port);
765 	if (net_debug > 5)
766 		printk(KERN_DEBUG " rx_count %04x %04x %04x %04x..", rx_head.pad,
767 			   rx_head.rx_count, rx_head.rx_status, rx_head.cur_addr);
768 	if ((rx_head.rx_status & 0x77) != 0x01) {
769 		dev->stats.rx_errors++;
770 		if (rx_head.rx_status & 0x0004) dev->stats.rx_frame_errors++;
771 		else if (rx_head.rx_status & 0x0002) dev->stats.rx_crc_errors++;
772 		if (net_debug > 3)
773 			printk(KERN_DEBUG "%s: Unknown ATP Rx error %04x.\n",
774 				   dev->name, rx_head.rx_status);
775 		if  (rx_head.rx_status & 0x0020) {
776 			dev->stats.rx_fifo_errors++;
777 			write_reg_high(ioaddr, CMR1, CMR1h_TxENABLE);
778 			write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);
779 		} else if (rx_head.rx_status & 0x0050)
780 			hardware_init(dev);
781 		return;
782 	} else {
783 		/* Malloc up new buffer. The "-4" omits the FCS (CRC). */
784 		int pkt_len = (rx_head.rx_count & 0x7ff) - 4;
785 		struct sk_buff *skb;
786 
787 		skb = netdev_alloc_skb(dev, pkt_len + 2);
788 		if (skb == NULL) {
789 			dev->stats.rx_dropped++;
790 			goto done;
791 		}
792 
793 		skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */
794 		read_block(ioaddr, pkt_len, skb_put(skb,pkt_len), dev->if_port);
795 		skb->protocol = eth_type_trans(skb, dev);
796 		netif_rx(skb);
797 		dev->stats.rx_packets++;
798 		dev->stats.rx_bytes += pkt_len;
799 	}
800  done:
801 	write_reg(ioaddr, CMR1, CMR1_NextPkt);
802 	lp->last_rx_time = jiffies;
803 }
804 
805 static void read_block(long ioaddr, int length, unsigned char *p, int data_mode)
806 {
807 	if (data_mode <= 3) { /* Mode 0 or 1 */
808 		outb(Ctrl_LNibRead, ioaddr + PAR_CONTROL);
809 		outb(length == 8  ?  RdAddr | HNib | MAR  :  RdAddr | MAR,
810 			 ioaddr + PAR_DATA);
811 		if (data_mode <= 1) { /* Mode 0 or 1 */
812 			do { *p++ = read_byte_mode0(ioaddr); } while (--length > 0);
813 		} else { /* Mode 2 or 3 */
814 			do { *p++ = read_byte_mode2(ioaddr); } while (--length > 0);
815 		}
816 	} else if (data_mode <= 5) {
817 		do { *p++ = read_byte_mode4(ioaddr); } while (--length > 0);
818 	} else {
819 		do { *p++ = read_byte_mode6(ioaddr); } while (--length > 0);
820 	}
821 
822 	outb(EOC+HNib+MAR, ioaddr + PAR_DATA);
823 	outb(Ctrl_SelData, ioaddr + PAR_CONTROL);
824 }
825 
826 /* The inverse routine to net_open(). */
827 static int
828 net_close(struct net_device *dev)
829 {
830 	struct net_local *lp = netdev_priv(dev);
831 	long ioaddr = dev->base_addr;
832 
833 	netif_stop_queue(dev);
834 
835 	del_timer_sync(&lp->timer);
836 
837 	/* Flush the Tx and disable Rx here. */
838 	lp->addr_mode = CMR2h_OFF;
839 	write_reg_high(ioaddr, CMR2, CMR2h_OFF);
840 
841 	/* Free the IRQ line. */
842 	outb(0x00, ioaddr + PAR_CONTROL);
843 	free_irq(dev->irq, dev);
844 
845 	/* Reset the ethernet hardware and activate the printer pass-through. */
846 	write_reg_high(ioaddr, CMR1, CMR1h_RESET | CMR1h_MUX);
847 	return 0;
848 }
849 
850 /*
851  *	Set or clear the multicast filter for this adapter.
852  */
853 
854 static void set_rx_mode(struct net_device *dev)
855 {
856 	struct net_local *lp = netdev_priv(dev);
857 	long ioaddr = dev->base_addr;
858 
859 	if (!netdev_mc_empty(dev) || (dev->flags & (IFF_ALLMULTI|IFF_PROMISC)))
860 		lp->addr_mode = CMR2h_PROMISC;
861 	else
862 		lp->addr_mode = CMR2h_Normal;
863 	write_reg_high(ioaddr, CMR2, lp->addr_mode);
864 }
865 
866 static int __init atp_init_module(void) {
867 	if (debug)					/* Emit version even if no cards detected. */
868 		printk(KERN_INFO "%s", version);
869 	return atp_init();
870 }
871 
872 static void __exit atp_cleanup_module(void) {
873 	struct net_device *next_dev;
874 
875 	while (root_atp_dev) {
876 		struct net_local *atp_local = netdev_priv(root_atp_dev);
877 		next_dev = atp_local->next_module;
878 		unregister_netdev(root_atp_dev);
879 		/* No need to release_region(), since we never snarf it. */
880 		free_netdev(root_atp_dev);
881 		root_atp_dev = next_dev;
882 	}
883 }
884 
885 module_init(atp_init_module);
886 module_exit(atp_cleanup_module);
887