xref: /openbmc/linux/drivers/char/ppdev.c (revision dea54fba)
1 /*
2  * linux/drivers/char/ppdev.c
3  *
4  * This is the code behind /dev/parport* -- it allows a user-space
5  * application to use the parport subsystem.
6  *
7  * Copyright (C) 1998-2000, 2002 Tim Waugh <tim@cyberelk.net>
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License
11  * as published by the Free Software Foundation; either version
12  * 2 of the License, or (at your option) any later version.
13  *
14  * A /dev/parportx device node represents an arbitrary device
15  * on port 'x'.  The following operations are possible:
16  *
17  * open		do nothing, set up default IEEE 1284 protocol to be COMPAT
18  * close	release port and unregister device (if necessary)
19  * ioctl
20  *   EXCL	register device exclusively (may fail)
21  *   CLAIM	(register device first time) parport_claim_or_block
22  *   RELEASE	parport_release
23  *   SETMODE	set the IEEE 1284 protocol to use for read/write
24  *   SETPHASE	set the IEEE 1284 phase of a particular mode.  Not to be
25  *              confused with ioctl(fd, SETPHASER, &stun). ;-)
26  *   DATADIR	data_forward / data_reverse
27  *   WDATA	write_data
28  *   RDATA	read_data
29  *   WCONTROL	write_control
30  *   RCONTROL	read_control
31  *   FCONTROL	frob_control
32  *   RSTATUS	read_status
33  *   NEGOT	parport_negotiate
34  *   YIELD	parport_yield_blocking
35  *   WCTLONIRQ	on interrupt, set control lines
36  *   CLRIRQ	clear (and return) interrupt count
37  *   SETTIME	sets device timeout (struct timeval)
38  *   GETTIME	gets device timeout (struct timeval)
39  *   GETMODES	gets hardware supported modes (unsigned int)
40  *   GETMODE	gets the current IEEE1284 mode
41  *   GETPHASE   gets the current IEEE1284 phase
42  *   GETFLAGS   gets current (user-visible) flags
43  *   SETFLAGS   sets current (user-visible) flags
44  * read/write	read or write in current IEEE 1284 protocol
45  * select	wait for interrupt (in readfds)
46  *
47  * Changes:
48  * Added SETTIME/GETTIME ioctl, Fred Barnes, 1999.
49  *
50  * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 2000/08/25
51  * - On error, copy_from_user and copy_to_user do not return -EFAULT,
52  *   They return the positive number of bytes *not* copied due to address
53  *   space errors.
54  *
55  * Added GETMODES/GETMODE/GETPHASE ioctls, Fred Barnes <frmb2@ukc.ac.uk>, 03/01/2001.
56  * Added GETFLAGS/SETFLAGS ioctls, Fred Barnes, 04/2001
57  */
58 
59 #include <linux/module.h>
60 #include <linux/init.h>
61 #include <linux/sched/signal.h>
62 #include <linux/device.h>
63 #include <linux/ioctl.h>
64 #include <linux/parport.h>
65 #include <linux/ctype.h>
66 #include <linux/poll.h>
67 #include <linux/slab.h>
68 #include <linux/major.h>
69 #include <linux/ppdev.h>
70 #include <linux/mutex.h>
71 #include <linux/uaccess.h>
72 #include <linux/compat.h>
73 
74 #define PP_VERSION "ppdev: user-space parallel port driver"
75 #define CHRDEV "ppdev"
76 
77 struct pp_struct {
78 	struct pardevice *pdev;
79 	wait_queue_head_t irq_wait;
80 	atomic_t irqc;
81 	unsigned int flags;
82 	int irqresponse;
83 	unsigned char irqctl;
84 	struct ieee1284_info state;
85 	struct ieee1284_info saved_state;
86 	long default_inactivity;
87 	int index;
88 };
89 
90 /* should we use PARDEVICE_MAX here? */
91 static struct device *devices[PARPORT_MAX];
92 
93 static DEFINE_IDA(ida_index);
94 
95 /* pp_struct.flags bitfields */
96 #define PP_CLAIMED    (1<<0)
97 #define PP_EXCL       (1<<1)
98 
99 /* Other constants */
100 #define PP_INTERRUPT_TIMEOUT (10 * HZ) /* 10s */
101 #define PP_BUFFER_SIZE 1024
102 #define PARDEVICE_MAX 8
103 
104 /* ROUND_UP macro from fs/select.c */
105 #define ROUND_UP(x,y) (((x)+(y)-1)/(y))
106 
107 static DEFINE_MUTEX(pp_do_mutex);
108 
109 /* define fixed sized ioctl cmd for y2038 migration */
110 #define PPGETTIME32	_IOR(PP_IOCTL, 0x95, s32[2])
111 #define PPSETTIME32	_IOW(PP_IOCTL, 0x96, s32[2])
112 #define PPGETTIME64	_IOR(PP_IOCTL, 0x95, s64[2])
113 #define PPSETTIME64	_IOW(PP_IOCTL, 0x96, s64[2])
114 
115 static inline void pp_enable_irq(struct pp_struct *pp)
116 {
117 	struct parport *port = pp->pdev->port;
118 
119 	port->ops->enable_irq(port);
120 }
121 
122 static ssize_t pp_read(struct file *file, char __user *buf, size_t count,
123 		       loff_t *ppos)
124 {
125 	unsigned int minor = iminor(file_inode(file));
126 	struct pp_struct *pp = file->private_data;
127 	char *kbuffer;
128 	ssize_t bytes_read = 0;
129 	struct parport *pport;
130 	int mode;
131 
132 	if (!(pp->flags & PP_CLAIMED)) {
133 		/* Don't have the port claimed */
134 		pr_debug(CHRDEV "%x: claim the port first\n", minor);
135 		return -EINVAL;
136 	}
137 
138 	/* Trivial case. */
139 	if (count == 0)
140 		return 0;
141 
142 	kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
143 	if (!kbuffer)
144 		return -ENOMEM;
145 	pport = pp->pdev->port;
146 	mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);
147 
148 	parport_set_timeout(pp->pdev,
149 			    (file->f_flags & O_NONBLOCK) ?
150 			    PARPORT_INACTIVITY_O_NONBLOCK :
151 			    pp->default_inactivity);
152 
153 	while (bytes_read == 0) {
154 		ssize_t need = min_t(unsigned long, count, PP_BUFFER_SIZE);
155 
156 		if (mode == IEEE1284_MODE_EPP) {
157 			/* various specials for EPP mode */
158 			int flags = 0;
159 			size_t (*fn)(struct parport *, void *, size_t, int);
160 
161 			if (pp->flags & PP_W91284PIC)
162 				flags |= PARPORT_W91284PIC;
163 			if (pp->flags & PP_FASTREAD)
164 				flags |= PARPORT_EPP_FAST;
165 			if (pport->ieee1284.mode & IEEE1284_ADDR)
166 				fn = pport->ops->epp_read_addr;
167 			else
168 				fn = pport->ops->epp_read_data;
169 			bytes_read = (*fn)(pport, kbuffer, need, flags);
170 		} else {
171 			bytes_read = parport_read(pport, kbuffer, need);
172 		}
173 
174 		if (bytes_read != 0)
175 			break;
176 
177 		if (file->f_flags & O_NONBLOCK) {
178 			bytes_read = -EAGAIN;
179 			break;
180 		}
181 
182 		if (signal_pending(current)) {
183 			bytes_read = -ERESTARTSYS;
184 			break;
185 		}
186 
187 		cond_resched();
188 	}
189 
190 	parport_set_timeout(pp->pdev, pp->default_inactivity);
191 
192 	if (bytes_read > 0 && copy_to_user(buf, kbuffer, bytes_read))
193 		bytes_read = -EFAULT;
194 
195 	kfree(kbuffer);
196 	pp_enable_irq(pp);
197 	return bytes_read;
198 }
199 
200 static ssize_t pp_write(struct file *file, const char __user *buf,
201 			size_t count, loff_t *ppos)
202 {
203 	unsigned int minor = iminor(file_inode(file));
204 	struct pp_struct *pp = file->private_data;
205 	char *kbuffer;
206 	ssize_t bytes_written = 0;
207 	ssize_t wrote;
208 	int mode;
209 	struct parport *pport;
210 
211 	if (!(pp->flags & PP_CLAIMED)) {
212 		/* Don't have the port claimed */
213 		pr_debug(CHRDEV "%x: claim the port first\n", minor);
214 		return -EINVAL;
215 	}
216 
217 	kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
218 	if (!kbuffer)
219 		return -ENOMEM;
220 
221 	pport = pp->pdev->port;
222 	mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);
223 
224 	parport_set_timeout(pp->pdev,
225 			    (file->f_flags & O_NONBLOCK) ?
226 			    PARPORT_INACTIVITY_O_NONBLOCK :
227 			    pp->default_inactivity);
228 
229 	while (bytes_written < count) {
230 		ssize_t n = min_t(unsigned long, count - bytes_written, PP_BUFFER_SIZE);
231 
232 		if (copy_from_user(kbuffer, buf + bytes_written, n)) {
233 			bytes_written = -EFAULT;
234 			break;
235 		}
236 
237 		if ((pp->flags & PP_FASTWRITE) && (mode == IEEE1284_MODE_EPP)) {
238 			/* do a fast EPP write */
239 			if (pport->ieee1284.mode & IEEE1284_ADDR) {
240 				wrote = pport->ops->epp_write_addr(pport,
241 					kbuffer, n, PARPORT_EPP_FAST);
242 			} else {
243 				wrote = pport->ops->epp_write_data(pport,
244 					kbuffer, n, PARPORT_EPP_FAST);
245 			}
246 		} else {
247 			wrote = parport_write(pp->pdev->port, kbuffer, n);
248 		}
249 
250 		if (wrote <= 0) {
251 			if (!bytes_written)
252 				bytes_written = wrote;
253 			break;
254 		}
255 
256 		bytes_written += wrote;
257 
258 		if (file->f_flags & O_NONBLOCK) {
259 			if (!bytes_written)
260 				bytes_written = -EAGAIN;
261 			break;
262 		}
263 
264 		if (signal_pending(current))
265 			break;
266 
267 		cond_resched();
268 	}
269 
270 	parport_set_timeout(pp->pdev, pp->default_inactivity);
271 
272 	kfree(kbuffer);
273 	pp_enable_irq(pp);
274 	return bytes_written;
275 }
276 
277 static void pp_irq(void *private)
278 {
279 	struct pp_struct *pp = private;
280 
281 	if (pp->irqresponse) {
282 		parport_write_control(pp->pdev->port, pp->irqctl);
283 		pp->irqresponse = 0;
284 	}
285 
286 	atomic_inc(&pp->irqc);
287 	wake_up_interruptible(&pp->irq_wait);
288 }
289 
290 static int register_device(int minor, struct pp_struct *pp)
291 {
292 	struct parport *port;
293 	struct pardevice *pdev = NULL;
294 	char *name;
295 	struct pardev_cb ppdev_cb;
296 	int rc = 0, index;
297 
298 	name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor);
299 	if (name == NULL)
300 		return -ENOMEM;
301 
302 	port = parport_find_number(minor);
303 	if (!port) {
304 		pr_warn("%s: no associated port!\n", name);
305 		rc = -ENXIO;
306 		goto err;
307 	}
308 
309 	index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
310 	memset(&ppdev_cb, 0, sizeof(ppdev_cb));
311 	ppdev_cb.irq_func = pp_irq;
312 	ppdev_cb.flags = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
313 	ppdev_cb.private = pp;
314 	pdev = parport_register_dev_model(port, name, &ppdev_cb, index);
315 	parport_put_port(port);
316 
317 	if (!pdev) {
318 		pr_warn("%s: failed to register device!\n", name);
319 		rc = -ENXIO;
320 		ida_simple_remove(&ida_index, index);
321 		goto err;
322 	}
323 
324 	pp->pdev = pdev;
325 	pp->index = index;
326 	dev_dbg(&pdev->dev, "registered pardevice\n");
327 err:
328 	kfree(name);
329 	return rc;
330 }
331 
332 static enum ieee1284_phase init_phase(int mode)
333 {
334 	switch (mode & ~(IEEE1284_DEVICEID
335 			 | IEEE1284_ADDR)) {
336 	case IEEE1284_MODE_NIBBLE:
337 	case IEEE1284_MODE_BYTE:
338 		return IEEE1284_PH_REV_IDLE;
339 	}
340 	return IEEE1284_PH_FWD_IDLE;
341 }
342 
343 static int pp_set_timeout(struct pardevice *pdev, long tv_sec, int tv_usec)
344 {
345 	long to_jiffies;
346 
347 	if ((tv_sec < 0) || (tv_usec < 0))
348 		return -EINVAL;
349 
350 	to_jiffies = usecs_to_jiffies(tv_usec);
351 	to_jiffies += tv_sec * HZ;
352 	if (to_jiffies <= 0)
353 		return -EINVAL;
354 
355 	pdev->timeout = to_jiffies;
356 	return 0;
357 }
358 
359 static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
360 {
361 	unsigned int minor = iminor(file_inode(file));
362 	struct pp_struct *pp = file->private_data;
363 	struct parport *port;
364 	void __user *argp = (void __user *)arg;
365 
366 	/* First handle the cases that don't take arguments. */
367 	switch (cmd) {
368 	case PPCLAIM:
369 	    {
370 		struct ieee1284_info *info;
371 		int ret;
372 
373 		if (pp->flags & PP_CLAIMED) {
374 			dev_dbg(&pp->pdev->dev, "you've already got it!\n");
375 			return -EINVAL;
376 		}
377 
378 		/* Deferred device registration. */
379 		if (!pp->pdev) {
380 			int err = register_device(minor, pp);
381 
382 			if (err)
383 				return err;
384 		}
385 
386 		ret = parport_claim_or_block(pp->pdev);
387 		if (ret < 0)
388 			return ret;
389 
390 		pp->flags |= PP_CLAIMED;
391 
392 		/* For interrupt-reporting to work, we need to be
393 		 * informed of each interrupt. */
394 		pp_enable_irq(pp);
395 
396 		/* We may need to fix up the state machine. */
397 		info = &pp->pdev->port->ieee1284;
398 		pp->saved_state.mode = info->mode;
399 		pp->saved_state.phase = info->phase;
400 		info->mode = pp->state.mode;
401 		info->phase = pp->state.phase;
402 		pp->default_inactivity = parport_set_timeout(pp->pdev, 0);
403 		parport_set_timeout(pp->pdev, pp->default_inactivity);
404 
405 		return 0;
406 	    }
407 	case PPEXCL:
408 		if (pp->pdev) {
409 			dev_dbg(&pp->pdev->dev,
410 				"too late for PPEXCL; already registered\n");
411 			if (pp->flags & PP_EXCL)
412 				/* But it's not really an error. */
413 				return 0;
414 			/* There's no chance of making the driver happy. */
415 			return -EINVAL;
416 		}
417 
418 		/* Just remember to register the device exclusively
419 		 * when we finally do the registration. */
420 		pp->flags |= PP_EXCL;
421 		return 0;
422 	case PPSETMODE:
423 	    {
424 		int mode;
425 
426 		if (copy_from_user(&mode, argp, sizeof(mode)))
427 			return -EFAULT;
428 		/* FIXME: validate mode */
429 		pp->state.mode = mode;
430 		pp->state.phase = init_phase(mode);
431 
432 		if (pp->flags & PP_CLAIMED) {
433 			pp->pdev->port->ieee1284.mode = mode;
434 			pp->pdev->port->ieee1284.phase = pp->state.phase;
435 		}
436 
437 		return 0;
438 	    }
439 	case PPGETMODE:
440 	    {
441 		int mode;
442 
443 		if (pp->flags & PP_CLAIMED)
444 			mode = pp->pdev->port->ieee1284.mode;
445 		else
446 			mode = pp->state.mode;
447 
448 		if (copy_to_user(argp, &mode, sizeof(mode)))
449 			return -EFAULT;
450 		return 0;
451 	    }
452 	case PPSETPHASE:
453 	    {
454 		int phase;
455 
456 		if (copy_from_user(&phase, argp, sizeof(phase)))
457 			return -EFAULT;
458 
459 		/* FIXME: validate phase */
460 		pp->state.phase = phase;
461 
462 		if (pp->flags & PP_CLAIMED)
463 			pp->pdev->port->ieee1284.phase = phase;
464 
465 		return 0;
466 	    }
467 	case PPGETPHASE:
468 	    {
469 		int phase;
470 
471 		if (pp->flags & PP_CLAIMED)
472 			phase = pp->pdev->port->ieee1284.phase;
473 		else
474 			phase = pp->state.phase;
475 		if (copy_to_user(argp, &phase, sizeof(phase)))
476 			return -EFAULT;
477 		return 0;
478 	    }
479 	case PPGETMODES:
480 	    {
481 		unsigned int modes;
482 
483 		port = parport_find_number(minor);
484 		if (!port)
485 			return -ENODEV;
486 
487 		modes = port->modes;
488 		parport_put_port(port);
489 		if (copy_to_user(argp, &modes, sizeof(modes)))
490 			return -EFAULT;
491 		return 0;
492 	    }
493 	case PPSETFLAGS:
494 	    {
495 		int uflags;
496 
497 		if (copy_from_user(&uflags, argp, sizeof(uflags)))
498 			return -EFAULT;
499 		pp->flags &= ~PP_FLAGMASK;
500 		pp->flags |= (uflags & PP_FLAGMASK);
501 		return 0;
502 	    }
503 	case PPGETFLAGS:
504 	    {
505 		int uflags;
506 
507 		uflags = pp->flags & PP_FLAGMASK;
508 		if (copy_to_user(argp, &uflags, sizeof(uflags)))
509 			return -EFAULT;
510 		return 0;
511 	    }
512 	}	/* end switch() */
513 
514 	/* Everything else requires the port to be claimed, so check
515 	 * that now. */
516 	if ((pp->flags & PP_CLAIMED) == 0) {
517 		pr_debug(CHRDEV "%x: claim the port first\n", minor);
518 		return -EINVAL;
519 	}
520 
521 	port = pp->pdev->port;
522 	switch (cmd) {
523 		struct ieee1284_info *info;
524 		unsigned char reg;
525 		unsigned char mask;
526 		int mode;
527 		s32 time32[2];
528 		s64 time64[2];
529 		struct timespec64 ts;
530 		int ret;
531 
532 	case PPRSTATUS:
533 		reg = parport_read_status(port);
534 		if (copy_to_user(argp, &reg, sizeof(reg)))
535 			return -EFAULT;
536 		return 0;
537 	case PPRDATA:
538 		reg = parport_read_data(port);
539 		if (copy_to_user(argp, &reg, sizeof(reg)))
540 			return -EFAULT;
541 		return 0;
542 	case PPRCONTROL:
543 		reg = parport_read_control(port);
544 		if (copy_to_user(argp, &reg, sizeof(reg)))
545 			return -EFAULT;
546 		return 0;
547 	case PPYIELD:
548 		parport_yield_blocking(pp->pdev);
549 		return 0;
550 
551 	case PPRELEASE:
552 		/* Save the state machine's state. */
553 		info = &pp->pdev->port->ieee1284;
554 		pp->state.mode = info->mode;
555 		pp->state.phase = info->phase;
556 		info->mode = pp->saved_state.mode;
557 		info->phase = pp->saved_state.phase;
558 		parport_release(pp->pdev);
559 		pp->flags &= ~PP_CLAIMED;
560 		return 0;
561 
562 	case PPWCONTROL:
563 		if (copy_from_user(&reg, argp, sizeof(reg)))
564 			return -EFAULT;
565 		parport_write_control(port, reg);
566 		return 0;
567 
568 	case PPWDATA:
569 		if (copy_from_user(&reg, argp, sizeof(reg)))
570 			return -EFAULT;
571 		parport_write_data(port, reg);
572 		return 0;
573 
574 	case PPFCONTROL:
575 		if (copy_from_user(&mask, argp,
576 				   sizeof(mask)))
577 			return -EFAULT;
578 		if (copy_from_user(&reg, 1 + (unsigned char __user *) arg,
579 				   sizeof(reg)))
580 			return -EFAULT;
581 		parport_frob_control(port, mask, reg);
582 		return 0;
583 
584 	case PPDATADIR:
585 		if (copy_from_user(&mode, argp, sizeof(mode)))
586 			return -EFAULT;
587 		if (mode)
588 			port->ops->data_reverse(port);
589 		else
590 			port->ops->data_forward(port);
591 		return 0;
592 
593 	case PPNEGOT:
594 		if (copy_from_user(&mode, argp, sizeof(mode)))
595 			return -EFAULT;
596 		switch ((ret = parport_negotiate(port, mode))) {
597 		case 0: break;
598 		case -1: /* handshake failed, peripheral not IEEE 1284 */
599 			ret = -EIO;
600 			break;
601 		case 1:  /* handshake succeeded, peripheral rejected mode */
602 			ret = -ENXIO;
603 			break;
604 		}
605 		pp_enable_irq(pp);
606 		return ret;
607 
608 	case PPWCTLONIRQ:
609 		if (copy_from_user(&reg, argp, sizeof(reg)))
610 			return -EFAULT;
611 
612 		/* Remember what to set the control lines to, for next
613 		 * time we get an interrupt. */
614 		pp->irqctl = reg;
615 		pp->irqresponse = 1;
616 		return 0;
617 
618 	case PPCLRIRQ:
619 		ret = atomic_read(&pp->irqc);
620 		if (copy_to_user(argp, &ret, sizeof(ret)))
621 			return -EFAULT;
622 		atomic_sub(ret, &pp->irqc);
623 		return 0;
624 
625 	case PPSETTIME32:
626 		if (copy_from_user(time32, argp, sizeof(time32)))
627 			return -EFAULT;
628 
629 		return pp_set_timeout(pp->pdev, time32[0], time32[1]);
630 
631 	case PPSETTIME64:
632 		if (copy_from_user(time64, argp, sizeof(time64)))
633 			return -EFAULT;
634 
635 		return pp_set_timeout(pp->pdev, time64[0], time64[1]);
636 
637 	case PPGETTIME32:
638 		jiffies_to_timespec64(pp->pdev->timeout, &ts);
639 		time32[0] = ts.tv_sec;
640 		time32[1] = ts.tv_nsec / NSEC_PER_USEC;
641 		if ((time32[0] < 0) || (time32[1] < 0))
642 			return -EINVAL;
643 
644 		if (copy_to_user(argp, time32, sizeof(time32)))
645 			return -EFAULT;
646 
647 		return 0;
648 
649 	case PPGETTIME64:
650 		jiffies_to_timespec64(pp->pdev->timeout, &ts);
651 		time64[0] = ts.tv_sec;
652 		time64[1] = ts.tv_nsec / NSEC_PER_USEC;
653 		if ((time64[0] < 0) || (time64[1] < 0))
654 			return -EINVAL;
655 
656 		if (copy_to_user(argp, time64, sizeof(time64)))
657 			return -EFAULT;
658 
659 		return 0;
660 
661 	default:
662 		dev_dbg(&pp->pdev->dev, "What? (cmd=0x%x)\n", cmd);
663 		return -EINVAL;
664 	}
665 
666 	/* Keep the compiler happy */
667 	return 0;
668 }
669 
670 static long pp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
671 {
672 	long ret;
673 
674 	mutex_lock(&pp_do_mutex);
675 	ret = pp_do_ioctl(file, cmd, arg);
676 	mutex_unlock(&pp_do_mutex);
677 	return ret;
678 }
679 
680 #ifdef CONFIG_COMPAT
681 static long pp_compat_ioctl(struct file *file, unsigned int cmd,
682 			    unsigned long arg)
683 {
684 	return pp_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
685 }
686 #endif
687 
688 static int pp_open(struct inode *inode, struct file *file)
689 {
690 	unsigned int minor = iminor(inode);
691 	struct pp_struct *pp;
692 
693 	if (minor >= PARPORT_MAX)
694 		return -ENXIO;
695 
696 	pp = kmalloc(sizeof(struct pp_struct), GFP_KERNEL);
697 	if (!pp)
698 		return -ENOMEM;
699 
700 	pp->state.mode = IEEE1284_MODE_COMPAT;
701 	pp->state.phase = init_phase(pp->state.mode);
702 	pp->flags = 0;
703 	pp->irqresponse = 0;
704 	atomic_set(&pp->irqc, 0);
705 	init_waitqueue_head(&pp->irq_wait);
706 
707 	/* Defer the actual device registration until the first claim.
708 	 * That way, we know whether or not the driver wants to have
709 	 * exclusive access to the port (PPEXCL).
710 	 */
711 	pp->pdev = NULL;
712 	file->private_data = pp;
713 
714 	return 0;
715 }
716 
717 static int pp_release(struct inode *inode, struct file *file)
718 {
719 	unsigned int minor = iminor(inode);
720 	struct pp_struct *pp = file->private_data;
721 	int compat_negot;
722 
723 	compat_negot = 0;
724 	if (!(pp->flags & PP_CLAIMED) && pp->pdev &&
725 	    (pp->state.mode != IEEE1284_MODE_COMPAT)) {
726 		struct ieee1284_info *info;
727 
728 		/* parport released, but not in compatibility mode */
729 		parport_claim_or_block(pp->pdev);
730 		pp->flags |= PP_CLAIMED;
731 		info = &pp->pdev->port->ieee1284;
732 		pp->saved_state.mode = info->mode;
733 		pp->saved_state.phase = info->phase;
734 		info->mode = pp->state.mode;
735 		info->phase = pp->state.phase;
736 		compat_negot = 1;
737 	} else if ((pp->flags & PP_CLAIMED) && pp->pdev &&
738 	    (pp->pdev->port->ieee1284.mode != IEEE1284_MODE_COMPAT)) {
739 		compat_negot = 2;
740 	}
741 	if (compat_negot) {
742 		parport_negotiate(pp->pdev->port, IEEE1284_MODE_COMPAT);
743 		dev_dbg(&pp->pdev->dev,
744 			"negotiated back to compatibility mode because user-space forgot\n");
745 	}
746 
747 	if (pp->flags & PP_CLAIMED) {
748 		struct ieee1284_info *info;
749 
750 		info = &pp->pdev->port->ieee1284;
751 		pp->state.mode = info->mode;
752 		pp->state.phase = info->phase;
753 		info->mode = pp->saved_state.mode;
754 		info->phase = pp->saved_state.phase;
755 		parport_release(pp->pdev);
756 		if (compat_negot != 1) {
757 			pr_debug(CHRDEV "%x: released pardevice "
758 				"because user-space forgot\n", minor);
759 		}
760 	}
761 
762 	if (pp->pdev) {
763 		parport_unregister_device(pp->pdev);
764 		ida_simple_remove(&ida_index, pp->index);
765 		pp->pdev = NULL;
766 		pr_debug(CHRDEV "%x: unregistered pardevice\n", minor);
767 	}
768 
769 	kfree(pp);
770 
771 	return 0;
772 }
773 
774 /* No kernel lock held - fine */
775 static unsigned int pp_poll(struct file *file, poll_table *wait)
776 {
777 	struct pp_struct *pp = file->private_data;
778 	unsigned int mask = 0;
779 
780 	poll_wait(file, &pp->irq_wait, wait);
781 	if (atomic_read(&pp->irqc))
782 		mask |= POLLIN | POLLRDNORM;
783 
784 	return mask;
785 }
786 
787 static struct class *ppdev_class;
788 
789 static const struct file_operations pp_fops = {
790 	.owner		= THIS_MODULE,
791 	.llseek		= no_llseek,
792 	.read		= pp_read,
793 	.write		= pp_write,
794 	.poll		= pp_poll,
795 	.unlocked_ioctl	= pp_ioctl,
796 #ifdef CONFIG_COMPAT
797 	.compat_ioctl   = pp_compat_ioctl,
798 #endif
799 	.open		= pp_open,
800 	.release	= pp_release,
801 };
802 
803 static void pp_attach(struct parport *port)
804 {
805 	struct device *ret;
806 
807 	if (devices[port->number])
808 		return;
809 
810 	ret = device_create(ppdev_class, port->dev,
811 			    MKDEV(PP_MAJOR, port->number), NULL,
812 			    "parport%d", port->number);
813 	if (IS_ERR(ret)) {
814 		pr_err("Failed to create device parport%d\n",
815 		       port->number);
816 		return;
817 	}
818 	devices[port->number] = ret;
819 }
820 
821 static void pp_detach(struct parport *port)
822 {
823 	if (!devices[port->number])
824 		return;
825 
826 	device_destroy(ppdev_class, MKDEV(PP_MAJOR, port->number));
827 	devices[port->number] = NULL;
828 }
829 
830 static int pp_probe(struct pardevice *par_dev)
831 {
832 	struct device_driver *drv = par_dev->dev.driver;
833 	int len = strlen(drv->name);
834 
835 	if (strncmp(par_dev->name, drv->name, len))
836 		return -ENODEV;
837 
838 	return 0;
839 }
840 
841 static struct parport_driver pp_driver = {
842 	.name		= CHRDEV,
843 	.probe		= pp_probe,
844 	.match_port	= pp_attach,
845 	.detach		= pp_detach,
846 	.devmodel	= true,
847 };
848 
849 static int __init ppdev_init(void)
850 {
851 	int err = 0;
852 
853 	if (register_chrdev(PP_MAJOR, CHRDEV, &pp_fops)) {
854 		pr_warn(CHRDEV ": unable to get major %d\n", PP_MAJOR);
855 		return -EIO;
856 	}
857 	ppdev_class = class_create(THIS_MODULE, CHRDEV);
858 	if (IS_ERR(ppdev_class)) {
859 		err = PTR_ERR(ppdev_class);
860 		goto out_chrdev;
861 	}
862 	err = parport_register_driver(&pp_driver);
863 	if (err < 0) {
864 		pr_warn(CHRDEV ": unable to register with parport\n");
865 		goto out_class;
866 	}
867 
868 	pr_info(PP_VERSION "\n");
869 	goto out;
870 
871 out_class:
872 	class_destroy(ppdev_class);
873 out_chrdev:
874 	unregister_chrdev(PP_MAJOR, CHRDEV);
875 out:
876 	return err;
877 }
878 
879 static void __exit ppdev_cleanup(void)
880 {
881 	/* Clean up all parport stuff */
882 	parport_unregister_driver(&pp_driver);
883 	class_destroy(ppdev_class);
884 	unregister_chrdev(PP_MAJOR, CHRDEV);
885 }
886 
887 module_init(ppdev_init);
888 module_exit(ppdev_cleanup);
889 
890 MODULE_LICENSE("GPL");
891 MODULE_ALIAS_CHARDEV_MAJOR(PP_MAJOR);
892