xref: /openbmc/linux/drivers/scsi/imm.c (revision 1da177e4)
1 /* imm.c   --  low level driver for the IOMEGA MatchMaker
2  * parallel port SCSI host adapter.
3  *
4  * (The IMM is the embedded controller in the ZIP Plus drive.)
5  *
6  * Current Maintainer: David Campbell (Perth, Western Australia)
7  *                     campbell@torque.net
8  *
9  * My unoffical company acronym list is 21 pages long:
10  *      FLA:    Four letter acronym with built in facility for
11  *              future expansion to five letters.
12  */
13 
14 #include <linux/config.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/blkdev.h>
19 #include <linux/parport.h>
20 #include <linux/workqueue.h>
21 #include <asm/io.h>
22 
23 #include <scsi/scsi.h>
24 #include <scsi/scsi_cmnd.h>
25 #include <scsi/scsi_device.h>
26 #include <scsi/scsi_host.h>
27 
28 /* The following #define is to avoid a clash with hosts.c */
29 #define IMM_PROBE_SPP   0x0001
30 #define IMM_PROBE_PS2   0x0002
31 #define IMM_PROBE_ECR   0x0010
32 #define IMM_PROBE_EPP17 0x0100
33 #define IMM_PROBE_EPP19 0x0200
34 
35 
36 typedef struct {
37 	struct pardevice *dev;	/* Parport device entry         */
38 	int base;		/* Actual port address          */
39 	int base_hi;		/* Hi Base address for ECP-ISA chipset */
40 	int mode;		/* Transfer mode                */
41 	struct scsi_cmnd *cur_cmd;	/* Current queued command       */
42 	struct work_struct imm_tq;	/* Polling interrupt stuff       */
43 	unsigned long jstart;	/* Jiffies at start             */
44 	unsigned failed:1;	/* Failure flag                 */
45 	unsigned dp:1;		/* Data phase present           */
46 	unsigned rd:1;		/* Read data in data phase      */
47 	unsigned wanted:1;	/* Parport sharing busy flag    */
48 	wait_queue_head_t *waiting;
49 	struct Scsi_Host *host;
50 	struct list_head list;
51 } imm_struct;
52 
53 static void imm_reset_pulse(unsigned int base);
54 static int device_check(imm_struct *dev);
55 
56 #include "imm.h"
57 
58 static inline imm_struct *imm_dev(struct Scsi_Host *host)
59 {
60 	return *(imm_struct **)&host->hostdata;
61 }
62 
63 static DEFINE_SPINLOCK(arbitration_lock);
64 
65 static void got_it(imm_struct *dev)
66 {
67 	dev->base = dev->dev->port->base;
68 	if (dev->cur_cmd)
69 		dev->cur_cmd->SCp.phase = 1;
70 	else
71 		wake_up(dev->waiting);
72 }
73 
74 static void imm_wakeup(void *ref)
75 {
76 	imm_struct *dev = (imm_struct *) ref;
77 	unsigned long flags;
78 
79 	spin_lock_irqsave(&arbitration_lock, flags);
80 	if (dev->wanted) {
81 		parport_claim(dev->dev);
82 		got_it(dev);
83 		dev->wanted = 0;
84 	}
85 	spin_unlock_irqrestore(&arbitration_lock, flags);
86 }
87 
88 static int imm_pb_claim(imm_struct *dev)
89 {
90 	unsigned long flags;
91 	int res = 1;
92 	spin_lock_irqsave(&arbitration_lock, flags);
93 	if (parport_claim(dev->dev) == 0) {
94 		got_it(dev);
95 		res = 0;
96 	}
97 	dev->wanted = res;
98 	spin_unlock_irqrestore(&arbitration_lock, flags);
99 	return res;
100 }
101 
102 static void imm_pb_dismiss(imm_struct *dev)
103 {
104 	unsigned long flags;
105 	int wanted;
106 	spin_lock_irqsave(&arbitration_lock, flags);
107 	wanted = dev->wanted;
108 	dev->wanted = 0;
109 	spin_unlock_irqrestore(&arbitration_lock, flags);
110 	if (!wanted)
111 		parport_release(dev->dev);
112 }
113 
114 static inline void imm_pb_release(imm_struct *dev)
115 {
116 	parport_release(dev->dev);
117 }
118 
119 /* This is to give the imm driver a way to modify the timings (and other
120  * parameters) by writing to the /proc/scsi/imm/0 file.
121  * Very simple method really... (Too simple, no error checking :( )
122  * Reason: Kernel hackers HATE having to unload and reload modules for
123  * testing...
124  * Also gives a method to use a script to obtain optimum timings (TODO)
125  */
126 static inline int imm_proc_write(imm_struct *dev, char *buffer, int length)
127 {
128 	unsigned long x;
129 
130 	if ((length > 5) && (strncmp(buffer, "mode=", 5) == 0)) {
131 		x = simple_strtoul(buffer + 5, NULL, 0);
132 		dev->mode = x;
133 		return length;
134 	}
135 	printk("imm /proc: invalid variable\n");
136 	return (-EINVAL);
137 }
138 
139 static int imm_proc_info(struct Scsi_Host *host, char *buffer, char **start,
140 			off_t offset, int length, int inout)
141 {
142 	imm_struct *dev = imm_dev(host);
143 	int len = 0;
144 
145 	if (inout)
146 		return imm_proc_write(dev, buffer, length);
147 
148 	len += sprintf(buffer + len, "Version : %s\n", IMM_VERSION);
149 	len +=
150 	    sprintf(buffer + len, "Parport : %s\n",
151 		    dev->dev->port->name);
152 	len +=
153 	    sprintf(buffer + len, "Mode    : %s\n",
154 		    IMM_MODE_STRING[dev->mode]);
155 
156 	/* Request for beyond end of buffer */
157 	if (offset > len)
158 		return 0;
159 
160 	*start = buffer + offset;
161 	len -= offset;
162 	if (len > length)
163 		len = length;
164 	return len;
165 }
166 
167 #if IMM_DEBUG > 0
168 #define imm_fail(x,y) printk("imm: imm_fail(%i) from %s at line %d\n",\
169 	   y, __FUNCTION__, __LINE__); imm_fail_func(x,y);
170 static inline void
171 imm_fail_func(imm_struct *dev, int error_code)
172 #else
173 static inline void
174 imm_fail(imm_struct *dev, int error_code)
175 #endif
176 {
177 	/* If we fail a device then we trash status / message bytes */
178 	if (dev->cur_cmd) {
179 		dev->cur_cmd->result = error_code << 16;
180 		dev->failed = 1;
181 	}
182 }
183 
184 /*
185  * Wait for the high bit to be set.
186  *
187  * In principle, this could be tied to an interrupt, but the adapter
188  * doesn't appear to be designed to support interrupts.  We spin on
189  * the 0x80 ready bit.
190  */
191 static unsigned char imm_wait(imm_struct *dev)
192 {
193 	int k;
194 	unsigned short ppb = dev->base;
195 	unsigned char r;
196 
197 	w_ctr(ppb, 0x0c);
198 
199 	k = IMM_SPIN_TMO;
200 	do {
201 		r = r_str(ppb);
202 		k--;
203 		udelay(1);
204 	}
205 	while (!(r & 0x80) && (k));
206 
207 	/*
208 	 * STR register (LPT base+1) to SCSI mapping:
209 	 *
210 	 * STR      imm     imm
211 	 * ===================================
212 	 * 0x80     S_REQ   S_REQ
213 	 * 0x40     !S_BSY  (????)
214 	 * 0x20     !S_CD   !S_CD
215 	 * 0x10     !S_IO   !S_IO
216 	 * 0x08     (????)  !S_BSY
217 	 *
218 	 * imm      imm     meaning
219 	 * ==================================
220 	 * 0xf0     0xb8    Bit mask
221 	 * 0xc0     0x88    ZIP wants more data
222 	 * 0xd0     0x98    ZIP wants to send more data
223 	 * 0xe0     0xa8    ZIP is expecting SCSI command data
224 	 * 0xf0     0xb8    end of transfer, ZIP is sending status
225 	 */
226 	w_ctr(ppb, 0x04);
227 	if (k)
228 		return (r & 0xb8);
229 
230 	/* Counter expired - Time out occurred */
231 	imm_fail(dev, DID_TIME_OUT);
232 	printk("imm timeout in imm_wait\n");
233 	return 0;		/* command timed out */
234 }
235 
236 static int imm_negotiate(imm_struct * tmp)
237 {
238 	/*
239 	 * The following is supposedly the IEEE 1284-1994 negotiate
240 	 * sequence. I have yet to obtain a copy of the above standard
241 	 * so this is a bit of a guess...
242 	 *
243 	 * A fair chunk of this is based on the Linux parport implementation
244 	 * of IEEE 1284.
245 	 *
246 	 * Return 0 if data available
247 	 *        1 if no data available
248 	 */
249 
250 	unsigned short base = tmp->base;
251 	unsigned char a, mode;
252 
253 	switch (tmp->mode) {
254 	case IMM_NIBBLE:
255 		mode = 0x00;
256 		break;
257 	case IMM_PS2:
258 		mode = 0x01;
259 		break;
260 	default:
261 		return 0;
262 	}
263 
264 	w_ctr(base, 0x04);
265 	udelay(5);
266 	w_dtr(base, mode);
267 	udelay(100);
268 	w_ctr(base, 0x06);
269 	udelay(5);
270 	a = (r_str(base) & 0x20) ? 0 : 1;
271 	udelay(5);
272 	w_ctr(base, 0x07);
273 	udelay(5);
274 	w_ctr(base, 0x06);
275 
276 	if (a) {
277 		printk
278 		    ("IMM: IEEE1284 negotiate indicates no data available.\n");
279 		imm_fail(tmp, DID_ERROR);
280 	}
281 	return a;
282 }
283 
284 /*
285  * Clear EPP timeout bit.
286  */
287 static inline void epp_reset(unsigned short ppb)
288 {
289 	int i;
290 
291 	i = r_str(ppb);
292 	w_str(ppb, i);
293 	w_str(ppb, i & 0xfe);
294 }
295 
296 /*
297  * Wait for empty ECP fifo (if we are in ECP fifo mode only)
298  */
299 static inline void ecp_sync(imm_struct *dev)
300 {
301 	int i, ppb_hi = dev->base_hi;
302 
303 	if (ppb_hi == 0)
304 		return;
305 
306 	if ((r_ecr(ppb_hi) & 0xe0) == 0x60) {	/* mode 011 == ECP fifo mode */
307 		for (i = 0; i < 100; i++) {
308 			if (r_ecr(ppb_hi) & 0x01)
309 				return;
310 			udelay(5);
311 		}
312 		printk("imm: ECP sync failed as data still present in FIFO.\n");
313 	}
314 }
315 
316 static int imm_byte_out(unsigned short base, const char *buffer, int len)
317 {
318 	int i;
319 
320 	w_ctr(base, 0x4);	/* apparently a sane mode */
321 	for (i = len >> 1; i; i--) {
322 		w_dtr(base, *buffer++);
323 		w_ctr(base, 0x5);	/* Drop STROBE low */
324 		w_dtr(base, *buffer++);
325 		w_ctr(base, 0x0);	/* STROBE high + INIT low */
326 	}
327 	w_ctr(base, 0x4);	/* apparently a sane mode */
328 	return 1;		/* All went well - we hope! */
329 }
330 
331 static int imm_nibble_in(unsigned short base, char *buffer, int len)
332 {
333 	unsigned char l;
334 	int i;
335 
336 	/*
337 	 * The following is based on documented timing signals
338 	 */
339 	w_ctr(base, 0x4);
340 	for (i = len; i; i--) {
341 		w_ctr(base, 0x6);
342 		l = (r_str(base) & 0xf0) >> 4;
343 		w_ctr(base, 0x5);
344 		*buffer++ = (r_str(base) & 0xf0) | l;
345 		w_ctr(base, 0x4);
346 	}
347 	return 1;		/* All went well - we hope! */
348 }
349 
350 static int imm_byte_in(unsigned short base, char *buffer, int len)
351 {
352 	int i;
353 
354 	/*
355 	 * The following is based on documented timing signals
356 	 */
357 	w_ctr(base, 0x4);
358 	for (i = len; i; i--) {
359 		w_ctr(base, 0x26);
360 		*buffer++ = r_dtr(base);
361 		w_ctr(base, 0x25);
362 	}
363 	return 1;		/* All went well - we hope! */
364 }
365 
366 static int imm_out(imm_struct *dev, char *buffer, int len)
367 {
368 	unsigned short ppb = dev->base;
369 	int r = imm_wait(dev);
370 
371 	/*
372 	 * Make sure that:
373 	 * a) the SCSI bus is BUSY (device still listening)
374 	 * b) the device is listening
375 	 */
376 	if ((r & 0x18) != 0x08) {
377 		imm_fail(dev, DID_ERROR);
378 		printk("IMM: returned SCSI status %2x\n", r);
379 		return 0;
380 	}
381 	switch (dev->mode) {
382 	case IMM_EPP_32:
383 	case IMM_EPP_16:
384 	case IMM_EPP_8:
385 		epp_reset(ppb);
386 		w_ctr(ppb, 0x4);
387 #ifdef CONFIG_SCSI_IZIP_EPP16
388 		if (!(((long) buffer | len) & 0x01))
389 			outsw(ppb + 4, buffer, len >> 1);
390 #else
391 		if (!(((long) buffer | len) & 0x03))
392 			outsl(ppb + 4, buffer, len >> 2);
393 #endif
394 		else
395 			outsb(ppb + 4, buffer, len);
396 		w_ctr(ppb, 0xc);
397 		r = !(r_str(ppb) & 0x01);
398 		w_ctr(ppb, 0xc);
399 		ecp_sync(dev);
400 		break;
401 
402 	case IMM_NIBBLE:
403 	case IMM_PS2:
404 		/* 8 bit output, with a loop */
405 		r = imm_byte_out(ppb, buffer, len);
406 		break;
407 
408 	default:
409 		printk("IMM: bug in imm_out()\n");
410 		r = 0;
411 	}
412 	return r;
413 }
414 
415 static int imm_in(imm_struct *dev, char *buffer, int len)
416 {
417 	unsigned short ppb = dev->base;
418 	int r = imm_wait(dev);
419 
420 	/*
421 	 * Make sure that:
422 	 * a) the SCSI bus is BUSY (device still listening)
423 	 * b) the device is sending data
424 	 */
425 	if ((r & 0x18) != 0x18) {
426 		imm_fail(dev, DID_ERROR);
427 		return 0;
428 	}
429 	switch (dev->mode) {
430 	case IMM_NIBBLE:
431 		/* 4 bit input, with a loop */
432 		r = imm_nibble_in(ppb, buffer, len);
433 		w_ctr(ppb, 0xc);
434 		break;
435 
436 	case IMM_PS2:
437 		/* 8 bit input, with a loop */
438 		r = imm_byte_in(ppb, buffer, len);
439 		w_ctr(ppb, 0xc);
440 		break;
441 
442 	case IMM_EPP_32:
443 	case IMM_EPP_16:
444 	case IMM_EPP_8:
445 		epp_reset(ppb);
446 		w_ctr(ppb, 0x24);
447 #ifdef CONFIG_SCSI_IZIP_EPP16
448 		if (!(((long) buffer | len) & 0x01))
449 			insw(ppb + 4, buffer, len >> 1);
450 #else
451 		if (!(((long) buffer | len) & 0x03))
452 			insl(ppb + 4, buffer, len >> 2);
453 #endif
454 		else
455 			insb(ppb + 4, buffer, len);
456 		w_ctr(ppb, 0x2c);
457 		r = !(r_str(ppb) & 0x01);
458 		w_ctr(ppb, 0x2c);
459 		ecp_sync(dev);
460 		break;
461 
462 	default:
463 		printk("IMM: bug in imm_ins()\n");
464 		r = 0;
465 		break;
466 	}
467 	return r;
468 }
469 
470 static int imm_cpp(unsigned short ppb, unsigned char b)
471 {
472 	/*
473 	 * Comments on udelay values refer to the
474 	 * Command Packet Protocol (CPP) timing diagram.
475 	 */
476 
477 	unsigned char s1, s2, s3;
478 	w_ctr(ppb, 0x0c);
479 	udelay(2);		/* 1 usec - infinite */
480 	w_dtr(ppb, 0xaa);
481 	udelay(10);		/* 7 usec - infinite */
482 	w_dtr(ppb, 0x55);
483 	udelay(10);		/* 7 usec - infinite */
484 	w_dtr(ppb, 0x00);
485 	udelay(10);		/* 7 usec - infinite */
486 	w_dtr(ppb, 0xff);
487 	udelay(10);		/* 7 usec - infinite */
488 	s1 = r_str(ppb) & 0xb8;
489 	w_dtr(ppb, 0x87);
490 	udelay(10);		/* 7 usec - infinite */
491 	s2 = r_str(ppb) & 0xb8;
492 	w_dtr(ppb, 0x78);
493 	udelay(10);		/* 7 usec - infinite */
494 	s3 = r_str(ppb) & 0x38;
495 	/*
496 	 * Values for b are:
497 	 * 0000 00aa    Assign address aa to current device
498 	 * 0010 00aa    Select device aa in EPP Winbond mode
499 	 * 0010 10aa    Select device aa in EPP mode
500 	 * 0011 xxxx    Deselect all devices
501 	 * 0110 00aa    Test device aa
502 	 * 1101 00aa    Select device aa in ECP mode
503 	 * 1110 00aa    Select device aa in Compatible mode
504 	 */
505 	w_dtr(ppb, b);
506 	udelay(2);		/* 1 usec - infinite */
507 	w_ctr(ppb, 0x0c);
508 	udelay(10);		/* 7 usec - infinite */
509 	w_ctr(ppb, 0x0d);
510 	udelay(2);		/* 1 usec - infinite */
511 	w_ctr(ppb, 0x0c);
512 	udelay(10);		/* 7 usec - infinite */
513 	w_dtr(ppb, 0xff);
514 	udelay(10);		/* 7 usec - infinite */
515 
516 	/*
517 	 * The following table is electrical pin values.
518 	 * (BSY is inverted at the CTR register)
519 	 *
520 	 *       BSY  ACK  POut SEL  Fault
521 	 * S1    0    X    1    1    1
522 	 * S2    1    X    0    1    1
523 	 * S3    L    X    1    1    S
524 	 *
525 	 * L => Last device in chain
526 	 * S => Selected
527 	 *
528 	 * Observered values for S1,S2,S3 are:
529 	 * Disconnect => f8/58/78
530 	 * Connect    => f8/58/70
531 	 */
532 	if ((s1 == 0xb8) && (s2 == 0x18) && (s3 == 0x30))
533 		return 1;	/* Connected */
534 	if ((s1 == 0xb8) && (s2 == 0x18) && (s3 == 0x38))
535 		return 0;	/* Disconnected */
536 
537 	return -1;		/* No device present */
538 }
539 
540 static inline int imm_connect(imm_struct *dev, int flag)
541 {
542 	unsigned short ppb = dev->base;
543 
544 	imm_cpp(ppb, 0xe0);	/* Select device 0 in compatible mode */
545 	imm_cpp(ppb, 0x30);	/* Disconnect all devices */
546 
547 	if ((dev->mode == IMM_EPP_8) ||
548 	    (dev->mode == IMM_EPP_16) ||
549 	    (dev->mode == IMM_EPP_32))
550 		return imm_cpp(ppb, 0x28);	/* Select device 0 in EPP mode */
551 	return imm_cpp(ppb, 0xe0);	/* Select device 0 in compatible mode */
552 }
553 
554 static void imm_disconnect(imm_struct *dev)
555 {
556 	imm_cpp(dev->base, 0x30);	/* Disconnect all devices */
557 }
558 
559 static int imm_select(imm_struct *dev, int target)
560 {
561 	int k;
562 	unsigned short ppb = dev->base;
563 
564 	/*
565 	 * Firstly we want to make sure there is nothing
566 	 * holding onto the SCSI bus.
567 	 */
568 	w_ctr(ppb, 0xc);
569 
570 	k = IMM_SELECT_TMO;
571 	do {
572 		k--;
573 	} while ((r_str(ppb) & 0x08) && (k));
574 
575 	if (!k)
576 		return 0;
577 
578 	/*
579 	 * Now assert the SCSI ID (HOST and TARGET) on the data bus
580 	 */
581 	w_ctr(ppb, 0x4);
582 	w_dtr(ppb, 0x80 | (1 << target));
583 	udelay(1);
584 
585 	/*
586 	 * Deassert SELIN first followed by STROBE
587 	 */
588 	w_ctr(ppb, 0xc);
589 	w_ctr(ppb, 0xd);
590 
591 	/*
592 	 * ACK should drop low while SELIN is deasserted.
593 	 * FAULT should drop low when the SCSI device latches the bus.
594 	 */
595 	k = IMM_SELECT_TMO;
596 	do {
597 		k--;
598 	}
599 	while (!(r_str(ppb) & 0x08) && (k));
600 
601 	/*
602 	 * Place the interface back into a sane state (status mode)
603 	 */
604 	w_ctr(ppb, 0xc);
605 	return (k) ? 1 : 0;
606 }
607 
608 static int imm_init(imm_struct *dev)
609 {
610 	if (imm_connect(dev, 0) != 1)
611 		return -EIO;
612 	imm_reset_pulse(dev->base);
613 	udelay(1000);	/* Delay to allow devices to settle */
614 	imm_disconnect(dev);
615 	udelay(1000);	/* Another delay to allow devices to settle */
616 	return device_check(dev);
617 }
618 
619 static inline int imm_send_command(struct scsi_cmnd *cmd)
620 {
621 	imm_struct *dev = imm_dev(cmd->device->host);
622 	int k;
623 
624 	/* NOTE: IMM uses byte pairs */
625 	for (k = 0; k < cmd->cmd_len; k += 2)
626 		if (!imm_out(dev, &cmd->cmnd[k], 2))
627 			return 0;
628 	return 1;
629 }
630 
631 /*
632  * The bulk flag enables some optimisations in the data transfer loops,
633  * it should be true for any command that transfers data in integral
634  * numbers of sectors.
635  *
636  * The driver appears to remain stable if we speed up the parallel port
637  * i/o in this function, but not elsewhere.
638  */
639 static int imm_completion(struct scsi_cmnd *cmd)
640 {
641 	/* Return codes:
642 	 * -1     Error
643 	 *  0     Told to schedule
644 	 *  1     Finished data transfer
645 	 */
646 	imm_struct *dev = imm_dev(cmd->device->host);
647 	unsigned short ppb = dev->base;
648 	unsigned long start_jiffies = jiffies;
649 
650 	unsigned char r, v;
651 	int fast, bulk, status;
652 
653 	v = cmd->cmnd[0];
654 	bulk = ((v == READ_6) ||
655 		(v == READ_10) || (v == WRITE_6) || (v == WRITE_10));
656 
657 	/*
658 	 * We only get here if the drive is ready to comunicate,
659 	 * hence no need for a full imm_wait.
660 	 */
661 	w_ctr(ppb, 0x0c);
662 	r = (r_str(ppb) & 0xb8);
663 
664 	/*
665 	 * while (device is not ready to send status byte)
666 	 *     loop;
667 	 */
668 	while (r != (unsigned char) 0xb8) {
669 		/*
670 		 * If we have been running for more than a full timer tick
671 		 * then take a rest.
672 		 */
673 		if (time_after(jiffies, start_jiffies + 1))
674 			return 0;
675 
676 		/*
677 		 * FAIL if:
678 		 * a) Drive status is screwy (!ready && !present)
679 		 * b) Drive is requesting/sending more data than expected
680 		 */
681 		if (((r & 0x88) != 0x88) || (cmd->SCp.this_residual <= 0)) {
682 			imm_fail(dev, DID_ERROR);
683 			return -1;	/* ERROR_RETURN */
684 		}
685 		/* determine if we should use burst I/O */
686 		if (dev->rd == 0) {
687 			fast = (bulk
688 				&& (cmd->SCp.this_residual >=
689 				    IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 2;
690 			status = imm_out(dev, cmd->SCp.ptr, fast);
691 		} else {
692 			fast = (bulk
693 				&& (cmd->SCp.this_residual >=
694 				    IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 1;
695 			status = imm_in(dev, cmd->SCp.ptr, fast);
696 		}
697 
698 		cmd->SCp.ptr += fast;
699 		cmd->SCp.this_residual -= fast;
700 
701 		if (!status) {
702 			imm_fail(dev, DID_BUS_BUSY);
703 			return -1;	/* ERROR_RETURN */
704 		}
705 		if (cmd->SCp.buffer && !cmd->SCp.this_residual) {
706 			/* if scatter/gather, advance to the next segment */
707 			if (cmd->SCp.buffers_residual--) {
708 				cmd->SCp.buffer++;
709 				cmd->SCp.this_residual =
710 				    cmd->SCp.buffer->length;
711 				cmd->SCp.ptr =
712 				    page_address(cmd->SCp.buffer->page) +
713 				    cmd->SCp.buffer->offset;
714 
715 				/*
716 				 * Make sure that we transfer even number of bytes
717 				 * otherwise it makes imm_byte_out() messy.
718 				 */
719 				if (cmd->SCp.this_residual & 0x01)
720 					cmd->SCp.this_residual++;
721 			}
722 		}
723 		/* Now check to see if the drive is ready to comunicate */
724 		w_ctr(ppb, 0x0c);
725 		r = (r_str(ppb) & 0xb8);
726 
727 		/* If not, drop back down to the scheduler and wait a timer tick */
728 		if (!(r & 0x80))
729 			return 0;
730 	}
731 	return 1;		/* FINISH_RETURN */
732 }
733 
734 /*
735  * Since the IMM itself doesn't generate interrupts, we use
736  * the scheduler's task queue to generate a stream of call-backs and
737  * complete the request when the drive is ready.
738  */
739 static void imm_interrupt(void *data)
740 {
741 	imm_struct *dev = (imm_struct *) data;
742 	struct scsi_cmnd *cmd = dev->cur_cmd;
743 	struct Scsi_Host *host = cmd->device->host;
744 	unsigned long flags;
745 
746 	if (!cmd) {
747 		printk("IMM: bug in imm_interrupt\n");
748 		return;
749 	}
750 	if (imm_engine(dev, cmd)) {
751 		INIT_WORK(&dev->imm_tq, imm_interrupt, (void *) dev);
752 		schedule_delayed_work(&dev->imm_tq, 1);
753 		return;
754 	}
755 	/* Command must of completed hence it is safe to let go... */
756 #if IMM_DEBUG > 0
757 	switch ((cmd->result >> 16) & 0xff) {
758 	case DID_OK:
759 		break;
760 	case DID_NO_CONNECT:
761 		printk("imm: no device at SCSI ID %i\n", cmd->device->id);
762 		break;
763 	case DID_BUS_BUSY:
764 		printk("imm: BUS BUSY - EPP timeout detected\n");
765 		break;
766 	case DID_TIME_OUT:
767 		printk("imm: unknown timeout\n");
768 		break;
769 	case DID_ABORT:
770 		printk("imm: told to abort\n");
771 		break;
772 	case DID_PARITY:
773 		printk("imm: parity error (???)\n");
774 		break;
775 	case DID_ERROR:
776 		printk("imm: internal driver error\n");
777 		break;
778 	case DID_RESET:
779 		printk("imm: told to reset device\n");
780 		break;
781 	case DID_BAD_INTR:
782 		printk("imm: bad interrupt (???)\n");
783 		break;
784 	default:
785 		printk("imm: bad return code (%02x)\n",
786 		       (cmd->result >> 16) & 0xff);
787 	}
788 #endif
789 
790 	if (cmd->SCp.phase > 1)
791 		imm_disconnect(dev);
792 
793 	imm_pb_dismiss(dev);
794 
795 	spin_lock_irqsave(host->host_lock, flags);
796 	dev->cur_cmd = NULL;
797 	cmd->scsi_done(cmd);
798 	spin_unlock_irqrestore(host->host_lock, flags);
799 	return;
800 }
801 
802 static int imm_engine(imm_struct *dev, struct scsi_cmnd *cmd)
803 {
804 	unsigned short ppb = dev->base;
805 	unsigned char l = 0, h = 0;
806 	int retv, x;
807 
808 	/* First check for any errors that may have occurred
809 	 * Here we check for internal errors
810 	 */
811 	if (dev->failed)
812 		return 0;
813 
814 	switch (cmd->SCp.phase) {
815 	case 0:		/* Phase 0 - Waiting for parport */
816 		if (time_after(jiffies, dev->jstart + HZ)) {
817 			/*
818 			 * We waited more than a second
819 			 * for parport to call us
820 			 */
821 			imm_fail(dev, DID_BUS_BUSY);
822 			return 0;
823 		}
824 		return 1;	/* wait until imm_wakeup claims parport */
825 		/* Phase 1 - Connected */
826 	case 1:
827 		imm_connect(dev, CONNECT_EPP_MAYBE);
828 		cmd->SCp.phase++;
829 
830 		/* Phase 2 - We are now talking to the scsi bus */
831 	case 2:
832 		if (!imm_select(dev, cmd->device->id)) {
833 			imm_fail(dev, DID_NO_CONNECT);
834 			return 0;
835 		}
836 		cmd->SCp.phase++;
837 
838 		/* Phase 3 - Ready to accept a command */
839 	case 3:
840 		w_ctr(ppb, 0x0c);
841 		if (!(r_str(ppb) & 0x80))
842 			return 1;
843 
844 		if (!imm_send_command(cmd))
845 			return 0;
846 		cmd->SCp.phase++;
847 
848 		/* Phase 4 - Setup scatter/gather buffers */
849 	case 4:
850 		if (cmd->use_sg) {
851 			/* if many buffers are available, start filling the first */
852 			cmd->SCp.buffer =
853 			    (struct scatterlist *) cmd->request_buffer;
854 			cmd->SCp.this_residual = cmd->SCp.buffer->length;
855 			cmd->SCp.ptr =
856 			    page_address(cmd->SCp.buffer->page) +
857 			    cmd->SCp.buffer->offset;
858 		} else {
859 			/* else fill the only available buffer */
860 			cmd->SCp.buffer = NULL;
861 			cmd->SCp.this_residual = cmd->request_bufflen;
862 			cmd->SCp.ptr = cmd->request_buffer;
863 		}
864 		cmd->SCp.buffers_residual = cmd->use_sg - 1;
865 		cmd->SCp.phase++;
866 		if (cmd->SCp.this_residual & 0x01)
867 			cmd->SCp.this_residual++;
868 		/* Phase 5 - Pre-Data transfer stage */
869 	case 5:
870 		/* Spin lock for BUSY */
871 		w_ctr(ppb, 0x0c);
872 		if (!(r_str(ppb) & 0x80))
873 			return 1;
874 
875 		/* Require negotiation for read requests */
876 		x = (r_str(ppb) & 0xb8);
877 		dev->rd = (x & 0x10) ? 1 : 0;
878 		dev->dp = (x & 0x20) ? 0 : 1;
879 
880 		if ((dev->dp) && (dev->rd))
881 			if (imm_negotiate(dev))
882 				return 0;
883 		cmd->SCp.phase++;
884 
885 		/* Phase 6 - Data transfer stage */
886 	case 6:
887 		/* Spin lock for BUSY */
888 		w_ctr(ppb, 0x0c);
889 		if (!(r_str(ppb) & 0x80))
890 			return 1;
891 
892 		if (dev->dp) {
893 			retv = imm_completion(cmd);
894 			if (retv == -1)
895 				return 0;
896 			if (retv == 0)
897 				return 1;
898 		}
899 		cmd->SCp.phase++;
900 
901 		/* Phase 7 - Post data transfer stage */
902 	case 7:
903 		if ((dev->dp) && (dev->rd)) {
904 			if ((dev->mode == IMM_NIBBLE) || (dev->mode == IMM_PS2)) {
905 				w_ctr(ppb, 0x4);
906 				w_ctr(ppb, 0xc);
907 				w_ctr(ppb, 0xe);
908 				w_ctr(ppb, 0x4);
909 			}
910 		}
911 		cmd->SCp.phase++;
912 
913 		/* Phase 8 - Read status/message */
914 	case 8:
915 		/* Check for data overrun */
916 		if (imm_wait(dev) != (unsigned char) 0xb8) {
917 			imm_fail(dev, DID_ERROR);
918 			return 0;
919 		}
920 		if (imm_negotiate(dev))
921 			return 0;
922 		if (imm_in(dev, &l, 1)) {	/* read status byte */
923 			/* Check for optional message byte */
924 			if (imm_wait(dev) == (unsigned char) 0xb8)
925 				imm_in(dev, &h, 1);
926 			cmd->result = (DID_OK << 16) + (l & STATUS_MASK);
927 		}
928 		if ((dev->mode == IMM_NIBBLE) || (dev->mode == IMM_PS2)) {
929 			w_ctr(ppb, 0x4);
930 			w_ctr(ppb, 0xc);
931 			w_ctr(ppb, 0xe);
932 			w_ctr(ppb, 0x4);
933 		}
934 		return 0;	/* Finished */
935 		break;
936 
937 	default:
938 		printk("imm: Invalid scsi phase\n");
939 	}
940 	return 0;
941 }
942 
943 static int imm_queuecommand(struct scsi_cmnd *cmd,
944 		void (*done)(struct scsi_cmnd *))
945 {
946 	imm_struct *dev = imm_dev(cmd->device->host);
947 
948 	if (dev->cur_cmd) {
949 		printk("IMM: bug in imm_queuecommand\n");
950 		return 0;
951 	}
952 	dev->failed = 0;
953 	dev->jstart = jiffies;
954 	dev->cur_cmd = cmd;
955 	cmd->scsi_done = done;
956 	cmd->result = DID_ERROR << 16;	/* default return code */
957 	cmd->SCp.phase = 0;	/* bus free */
958 
959 	INIT_WORK(&dev->imm_tq, imm_interrupt, dev);
960 	schedule_work(&dev->imm_tq);
961 
962 	imm_pb_claim(dev);
963 
964 	return 0;
965 }
966 
967 /*
968  * Apparently the disk->capacity attribute is off by 1 sector
969  * for all disk drives.  We add the one here, but it should really
970  * be done in sd.c.  Even if it gets fixed there, this will still
971  * work.
972  */
973 static int imm_biosparam(struct scsi_device *sdev, struct block_device *dev,
974 			 sector_t capacity, int ip[])
975 {
976 	ip[0] = 0x40;
977 	ip[1] = 0x20;
978 	ip[2] = ((unsigned long) capacity + 1) / (ip[0] * ip[1]);
979 	if (ip[2] > 1024) {
980 		ip[0] = 0xff;
981 		ip[1] = 0x3f;
982 		ip[2] = ((unsigned long) capacity + 1) / (ip[0] * ip[1]);
983 	}
984 	return 0;
985 }
986 
987 static int imm_abort(struct scsi_cmnd *cmd)
988 {
989 	imm_struct *dev = imm_dev(cmd->device->host);
990 	/*
991 	 * There is no method for aborting commands since Iomega
992 	 * have tied the SCSI_MESSAGE line high in the interface
993 	 */
994 
995 	switch (cmd->SCp.phase) {
996 	case 0:		/* Do not have access to parport */
997 	case 1:		/* Have not connected to interface */
998 		dev->cur_cmd = NULL;	/* Forget the problem */
999 		return SUCCESS;
1000 		break;
1001 	default:		/* SCSI command sent, can not abort */
1002 		return FAILED;
1003 		break;
1004 	}
1005 }
1006 
1007 static void imm_reset_pulse(unsigned int base)
1008 {
1009 	w_ctr(base, 0x04);
1010 	w_dtr(base, 0x40);
1011 	udelay(1);
1012 	w_ctr(base, 0x0c);
1013 	w_ctr(base, 0x0d);
1014 	udelay(50);
1015 	w_ctr(base, 0x0c);
1016 	w_ctr(base, 0x04);
1017 }
1018 
1019 static int imm_reset(struct scsi_cmnd *cmd)
1020 {
1021 	imm_struct *dev = imm_dev(cmd->device->host);
1022 
1023 	if (cmd->SCp.phase)
1024 		imm_disconnect(dev);
1025 	dev->cur_cmd = NULL;	/* Forget the problem */
1026 
1027 	imm_connect(dev, CONNECT_NORMAL);
1028 	imm_reset_pulse(dev->base);
1029 	udelay(1000);		/* device settle delay */
1030 	imm_disconnect(dev);
1031 	udelay(1000);		/* device settle delay */
1032 	return SUCCESS;
1033 }
1034 
1035 static int device_check(imm_struct *dev)
1036 {
1037 	/* This routine looks for a device and then attempts to use EPP
1038 	   to send a command. If all goes as planned then EPP is available. */
1039 
1040 	static char cmd[6] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
1041 	int loop, old_mode, status, k, ppb = dev->base;
1042 	unsigned char l;
1043 
1044 	old_mode = dev->mode;
1045 	for (loop = 0; loop < 8; loop++) {
1046 		/* Attempt to use EPP for Test Unit Ready */
1047 		if ((ppb & 0x0007) == 0x0000)
1048 			dev->mode = IMM_EPP_32;
1049 
1050 	      second_pass:
1051 		imm_connect(dev, CONNECT_EPP_MAYBE);
1052 		/* Select SCSI device */
1053 		if (!imm_select(dev, loop)) {
1054 			imm_disconnect(dev);
1055 			continue;
1056 		}
1057 		printk("imm: Found device at ID %i, Attempting to use %s\n",
1058 		       loop, IMM_MODE_STRING[dev->mode]);
1059 
1060 		/* Send SCSI command */
1061 		status = 1;
1062 		w_ctr(ppb, 0x0c);
1063 		for (l = 0; (l < 3) && (status); l++)
1064 			status = imm_out(dev, &cmd[l << 1], 2);
1065 
1066 		if (!status) {
1067 			imm_disconnect(dev);
1068 			imm_connect(dev, CONNECT_EPP_MAYBE);
1069 			imm_reset_pulse(dev->base);
1070 			udelay(1000);
1071 			imm_disconnect(dev);
1072 			udelay(1000);
1073 			if (dev->mode == IMM_EPP_32) {
1074 				dev->mode = old_mode;
1075 				goto second_pass;
1076 			}
1077 			printk("imm: Unable to establish communication\n");
1078 			return -EIO;
1079 		}
1080 		w_ctr(ppb, 0x0c);
1081 
1082 		k = 1000000;	/* 1 Second */
1083 		do {
1084 			l = r_str(ppb);
1085 			k--;
1086 			udelay(1);
1087 		} while (!(l & 0x80) && (k));
1088 
1089 		l &= 0xb8;
1090 
1091 		if (l != 0xb8) {
1092 			imm_disconnect(dev);
1093 			imm_connect(dev, CONNECT_EPP_MAYBE);
1094 			imm_reset_pulse(dev->base);
1095 			udelay(1000);
1096 			imm_disconnect(dev);
1097 			udelay(1000);
1098 			if (dev->mode == IMM_EPP_32) {
1099 				dev->mode = old_mode;
1100 				goto second_pass;
1101 			}
1102 			printk
1103 			    ("imm: Unable to establish communication\n");
1104 			return -EIO;
1105 		}
1106 		imm_disconnect(dev);
1107 		printk
1108 		    ("imm: Communication established at 0x%x with ID %i using %s\n",
1109 		     ppb, loop, IMM_MODE_STRING[dev->mode]);
1110 		imm_connect(dev, CONNECT_EPP_MAYBE);
1111 		imm_reset_pulse(dev->base);
1112 		udelay(1000);
1113 		imm_disconnect(dev);
1114 		udelay(1000);
1115 		return 0;
1116 	}
1117 	printk("imm: No devices found\n");
1118 	return -ENODEV;
1119 }
1120 
1121 static int imm_adjust_queue(struct scsi_device *device)
1122 {
1123 	blk_queue_bounce_limit(device->request_queue, BLK_BOUNCE_HIGH);
1124 	return 0;
1125 }
1126 
1127 static struct scsi_host_template imm_template = {
1128 	.module			= THIS_MODULE,
1129 	.proc_name		= "imm",
1130 	.proc_info		= imm_proc_info,
1131 	.name			= "Iomega VPI2 (imm) interface",
1132 	.queuecommand		= imm_queuecommand,
1133 	.eh_abort_handler	= imm_abort,
1134 	.eh_bus_reset_handler	= imm_reset,
1135 	.eh_host_reset_handler	= imm_reset,
1136 	.bios_param		= imm_biosparam,
1137 	.this_id		= 7,
1138 	.sg_tablesize		= SG_ALL,
1139 	.cmd_per_lun		= 1,
1140 	.use_clustering		= ENABLE_CLUSTERING,
1141 	.can_queue		= 1,
1142 	.slave_alloc		= imm_adjust_queue,
1143 	.unchecked_isa_dma	= 1, /* imm cannot deal with highmem, so
1144 				      * this is an easy trick to ensure
1145 				      * all io pages for this host reside
1146 				      * in low memory */
1147 };
1148 
1149 /***************************************************************************
1150  *                   Parallel port probing routines                        *
1151  ***************************************************************************/
1152 
1153 static LIST_HEAD(imm_hosts);
1154 
1155 static int __imm_attach(struct parport *pb)
1156 {
1157 	struct Scsi_Host *host;
1158 	imm_struct *dev;
1159 	DECLARE_WAIT_QUEUE_HEAD(waiting);
1160 	DEFINE_WAIT(wait);
1161 	int ports;
1162 	int modes, ppb;
1163 	int err = -ENOMEM;
1164 
1165 	init_waitqueue_head(&waiting);
1166 
1167 	dev = kmalloc(sizeof(imm_struct), GFP_KERNEL);
1168 	if (!dev)
1169 		return -ENOMEM;
1170 
1171 	memset(dev, 0, sizeof(imm_struct));
1172 
1173 	dev->base = -1;
1174 	dev->mode = IMM_AUTODETECT;
1175 	INIT_LIST_HEAD(&dev->list);
1176 
1177 	dev->dev = parport_register_device(pb, "imm", NULL, imm_wakeup,
1178 						NULL, 0, dev);
1179 
1180 	if (!dev->dev)
1181 		goto out;
1182 
1183 
1184 	/* Claim the bus so it remembers what we do to the control
1185 	 * registers. [ CTR and ECP ]
1186 	 */
1187 	err = -EBUSY;
1188 	dev->waiting = &waiting;
1189 	prepare_to_wait(&waiting, &wait, TASK_UNINTERRUPTIBLE);
1190 	if (imm_pb_claim(dev))
1191 		schedule_timeout(3 * HZ);
1192 	if (dev->wanted) {
1193 		printk(KERN_ERR "imm%d: failed to claim parport because "
1194 			"a pardevice is owning the port for too long "
1195 			"time!\n", pb->number);
1196 		imm_pb_dismiss(dev);
1197 		dev->waiting = NULL;
1198 		finish_wait(&waiting, &wait);
1199 		goto out1;
1200 	}
1201 	dev->waiting = NULL;
1202 	finish_wait(&waiting, &wait);
1203 	ppb = dev->base = dev->dev->port->base;
1204 	dev->base_hi = dev->dev->port->base_hi;
1205 	w_ctr(ppb, 0x0c);
1206 	modes = dev->dev->port->modes;
1207 
1208 	/* Mode detection works up the chain of speed
1209 	 * This avoids a nasty if-then-else-if-... tree
1210 	 */
1211 	dev->mode = IMM_NIBBLE;
1212 
1213 	if (modes & PARPORT_MODE_TRISTATE)
1214 		dev->mode = IMM_PS2;
1215 
1216 	/* Done configuration */
1217 
1218 	err = imm_init(dev);
1219 
1220 	imm_pb_release(dev);
1221 
1222 	if (err)
1223 		goto out1;
1224 
1225 	/* now the glue ... */
1226 	if (dev->mode == IMM_NIBBLE || dev->mode == IMM_PS2)
1227 		ports = 3;
1228 	else
1229 		ports = 8;
1230 
1231 	INIT_WORK(&dev->imm_tq, imm_interrupt, dev);
1232 
1233 	err = -ENOMEM;
1234 	host = scsi_host_alloc(&imm_template, sizeof(imm_struct *));
1235 	if (!host)
1236 		goto out1;
1237 	host->io_port = pb->base;
1238 	host->n_io_port = ports;
1239 	host->dma_channel = -1;
1240 	host->unique_id = pb->number;
1241 	*(imm_struct **)&host->hostdata = dev;
1242 	dev->host = host;
1243 	list_add_tail(&dev->list, &imm_hosts);
1244 	err = scsi_add_host(host, NULL);
1245 	if (err)
1246 		goto out2;
1247 	scsi_scan_host(host);
1248 	return 0;
1249 
1250 out2:
1251 	list_del_init(&dev->list);
1252 	scsi_host_put(host);
1253 out1:
1254 	parport_unregister_device(dev->dev);
1255 out:
1256 	kfree(dev);
1257 	return err;
1258 }
1259 
1260 static void imm_attach(struct parport *pb)
1261 {
1262 	__imm_attach(pb);
1263 }
1264 
1265 static void imm_detach(struct parport *pb)
1266 {
1267 	imm_struct *dev;
1268 	list_for_each_entry(dev, &imm_hosts, list) {
1269 		if (dev->dev->port == pb) {
1270 			list_del_init(&dev->list);
1271 			scsi_remove_host(dev->host);
1272 			scsi_host_put(dev->host);
1273 			parport_unregister_device(dev->dev);
1274 			kfree(dev);
1275 			break;
1276 		}
1277 	}
1278 }
1279 
1280 static struct parport_driver imm_driver = {
1281 	.name	= "imm",
1282 	.attach	= imm_attach,
1283 	.detach	= imm_detach,
1284 };
1285 
1286 static int __init imm_driver_init(void)
1287 {
1288 	printk("imm: Version %s\n", IMM_VERSION);
1289 	return parport_register_driver(&imm_driver);
1290 }
1291 
1292 static void __exit imm_driver_exit(void)
1293 {
1294 	parport_unregister_driver(&imm_driver);
1295 }
1296 
1297 module_init(imm_driver_init);
1298 module_exit(imm_driver_exit);
1299 
1300 MODULE_LICENSE("GPL");
1301