xref: /openbmc/linux/drivers/char/ppdev.c (revision 3db55767)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * linux/drivers/char/ppdev.c
4  *
5  * This is the code behind /dev/parport* -- it allows a user-space
6  * application to use the parport subsystem.
7  *
8  * Copyright (C) 1998-2000, 2002 Tim Waugh <tim@cyberelk.net>
9  *
10  * A /dev/parportx device node represents an arbitrary device
11  * on port 'x'.  The following operations are possible:
12  *
13  * open		do nothing, set up default IEEE 1284 protocol to be COMPAT
14  * close	release port and unregister device (if necessary)
15  * ioctl
16  *   EXCL	register device exclusively (may fail)
17  *   CLAIM	(register device first time) parport_claim_or_block
18  *   RELEASE	parport_release
19  *   SETMODE	set the IEEE 1284 protocol to use for read/write
20  *   SETPHASE	set the IEEE 1284 phase of a particular mode.  Not to be
21  *              confused with ioctl(fd, SETPHASER, &stun). ;-)
22  *   DATADIR	data_forward / data_reverse
23  *   WDATA	write_data
24  *   RDATA	read_data
25  *   WCONTROL	write_control
26  *   RCONTROL	read_control
27  *   FCONTROL	frob_control
28  *   RSTATUS	read_status
29  *   NEGOT	parport_negotiate
30  *   YIELD	parport_yield_blocking
31  *   WCTLONIRQ	on interrupt, set control lines
32  *   CLRIRQ	clear (and return) interrupt count
33  *   SETTIME	sets device timeout (struct timeval)
34  *   GETTIME	gets device timeout (struct timeval)
35  *   GETMODES	gets hardware supported modes (unsigned int)
36  *   GETMODE	gets the current IEEE1284 mode
37  *   GETPHASE   gets the current IEEE1284 phase
38  *   GETFLAGS   gets current (user-visible) flags
39  *   SETFLAGS   sets current (user-visible) flags
40  * read/write	read or write in current IEEE 1284 protocol
41  * select	wait for interrupt (in readfds)
42  *
43  * Changes:
44  * Added SETTIME/GETTIME ioctl, Fred Barnes, 1999.
45  *
46  * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 2000/08/25
47  * - On error, copy_from_user and copy_to_user do not return -EFAULT,
48  *   They return the positive number of bytes *not* copied due to address
49  *   space errors.
50  *
51  * Added GETMODES/GETMODE/GETPHASE ioctls, Fred Barnes <frmb2@ukc.ac.uk>, 03/01/2001.
52  * Added GETFLAGS/SETFLAGS ioctls, Fred Barnes, 04/2001
53  */
54 
55 #include <linux/module.h>
56 #include <linux/init.h>
57 #include <linux/sched/signal.h>
58 #include <linux/device.h>
59 #include <linux/ioctl.h>
60 #include <linux/parport.h>
61 #include <linux/ctype.h>
62 #include <linux/poll.h>
63 #include <linux/slab.h>
64 #include <linux/major.h>
65 #include <linux/ppdev.h>
66 #include <linux/mutex.h>
67 #include <linux/uaccess.h>
68 #include <linux/compat.h>
69 
70 #define PP_VERSION "ppdev: user-space parallel port driver"
71 #define CHRDEV "ppdev"
72 
73 struct pp_struct {
74 	struct pardevice *pdev;
75 	wait_queue_head_t irq_wait;
76 	atomic_t irqc;
77 	unsigned int flags;
78 	int irqresponse;
79 	unsigned char irqctl;
80 	struct ieee1284_info state;
81 	struct ieee1284_info saved_state;
82 	long default_inactivity;
83 	int index;
84 };
85 
86 /* should we use PARDEVICE_MAX here? */
87 static struct device *devices[PARPORT_MAX];
88 
89 static DEFINE_IDA(ida_index);
90 
91 /* pp_struct.flags bitfields */
92 #define PP_CLAIMED    (1<<0)
93 #define PP_EXCL       (1<<1)
94 
95 /* Other constants */
96 #define PP_INTERRUPT_TIMEOUT (10 * HZ) /* 10s */
97 #define PP_BUFFER_SIZE 1024
98 #define PARDEVICE_MAX 8
99 
100 static DEFINE_MUTEX(pp_do_mutex);
101 
102 /* define fixed sized ioctl cmd for y2038 migration */
103 #define PPGETTIME32	_IOR(PP_IOCTL, 0x95, s32[2])
104 #define PPSETTIME32	_IOW(PP_IOCTL, 0x96, s32[2])
105 #define PPGETTIME64	_IOR(PP_IOCTL, 0x95, s64[2])
106 #define PPSETTIME64	_IOW(PP_IOCTL, 0x96, s64[2])
107 
108 static inline void pp_enable_irq(struct pp_struct *pp)
109 {
110 	struct parport *port = pp->pdev->port;
111 
112 	port->ops->enable_irq(port);
113 }
114 
115 static ssize_t pp_read(struct file *file, char __user *buf, size_t count,
116 		       loff_t *ppos)
117 {
118 	unsigned int minor = iminor(file_inode(file));
119 	struct pp_struct *pp = file->private_data;
120 	char *kbuffer;
121 	ssize_t bytes_read = 0;
122 	struct parport *pport;
123 	int mode;
124 
125 	if (!(pp->flags & PP_CLAIMED)) {
126 		/* Don't have the port claimed */
127 		pr_debug(CHRDEV "%x: claim the port first\n", minor);
128 		return -EINVAL;
129 	}
130 
131 	/* Trivial case. */
132 	if (count == 0)
133 		return 0;
134 
135 	kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
136 	if (!kbuffer)
137 		return -ENOMEM;
138 	pport = pp->pdev->port;
139 	mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);
140 
141 	parport_set_timeout(pp->pdev,
142 			    (file->f_flags & O_NONBLOCK) ?
143 			    PARPORT_INACTIVITY_O_NONBLOCK :
144 			    pp->default_inactivity);
145 
146 	while (bytes_read == 0) {
147 		ssize_t need = min_t(unsigned long, count, PP_BUFFER_SIZE);
148 
149 		if (mode == IEEE1284_MODE_EPP) {
150 			/* various specials for EPP mode */
151 			int flags = 0;
152 			size_t (*fn)(struct parport *, void *, size_t, int);
153 
154 			if (pp->flags & PP_W91284PIC)
155 				flags |= PARPORT_W91284PIC;
156 			if (pp->flags & PP_FASTREAD)
157 				flags |= PARPORT_EPP_FAST;
158 			if (pport->ieee1284.mode & IEEE1284_ADDR)
159 				fn = pport->ops->epp_read_addr;
160 			else
161 				fn = pport->ops->epp_read_data;
162 			bytes_read = (*fn)(pport, kbuffer, need, flags);
163 		} else {
164 			bytes_read = parport_read(pport, kbuffer, need);
165 		}
166 
167 		if (bytes_read != 0)
168 			break;
169 
170 		if (file->f_flags & O_NONBLOCK) {
171 			bytes_read = -EAGAIN;
172 			break;
173 		}
174 
175 		if (signal_pending(current)) {
176 			bytes_read = -ERESTARTSYS;
177 			break;
178 		}
179 
180 		cond_resched();
181 	}
182 
183 	parport_set_timeout(pp->pdev, pp->default_inactivity);
184 
185 	if (bytes_read > 0 && copy_to_user(buf, kbuffer, bytes_read))
186 		bytes_read = -EFAULT;
187 
188 	kfree(kbuffer);
189 	pp_enable_irq(pp);
190 	return bytes_read;
191 }
192 
193 static ssize_t pp_write(struct file *file, const char __user *buf,
194 			size_t count, loff_t *ppos)
195 {
196 	unsigned int minor = iminor(file_inode(file));
197 	struct pp_struct *pp = file->private_data;
198 	char *kbuffer;
199 	ssize_t bytes_written = 0;
200 	ssize_t wrote;
201 	int mode;
202 	struct parport *pport;
203 
204 	if (!(pp->flags & PP_CLAIMED)) {
205 		/* Don't have the port claimed */
206 		pr_debug(CHRDEV "%x: claim the port first\n", minor);
207 		return -EINVAL;
208 	}
209 
210 	kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
211 	if (!kbuffer)
212 		return -ENOMEM;
213 
214 	pport = pp->pdev->port;
215 	mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);
216 
217 	parport_set_timeout(pp->pdev,
218 			    (file->f_flags & O_NONBLOCK) ?
219 			    PARPORT_INACTIVITY_O_NONBLOCK :
220 			    pp->default_inactivity);
221 
222 	while (bytes_written < count) {
223 		ssize_t n = min_t(unsigned long, count - bytes_written, PP_BUFFER_SIZE);
224 
225 		if (copy_from_user(kbuffer, buf + bytes_written, n)) {
226 			bytes_written = -EFAULT;
227 			break;
228 		}
229 
230 		if ((pp->flags & PP_FASTWRITE) && (mode == IEEE1284_MODE_EPP)) {
231 			/* do a fast EPP write */
232 			if (pport->ieee1284.mode & IEEE1284_ADDR) {
233 				wrote = pport->ops->epp_write_addr(pport,
234 					kbuffer, n, PARPORT_EPP_FAST);
235 			} else {
236 				wrote = pport->ops->epp_write_data(pport,
237 					kbuffer, n, PARPORT_EPP_FAST);
238 			}
239 		} else {
240 			wrote = parport_write(pp->pdev->port, kbuffer, n);
241 		}
242 
243 		if (wrote <= 0) {
244 			if (!bytes_written)
245 				bytes_written = wrote;
246 			break;
247 		}
248 
249 		bytes_written += wrote;
250 
251 		if (file->f_flags & O_NONBLOCK) {
252 			if (!bytes_written)
253 				bytes_written = -EAGAIN;
254 			break;
255 		}
256 
257 		if (signal_pending(current))
258 			break;
259 
260 		cond_resched();
261 	}
262 
263 	parport_set_timeout(pp->pdev, pp->default_inactivity);
264 
265 	kfree(kbuffer);
266 	pp_enable_irq(pp);
267 	return bytes_written;
268 }
269 
270 static void pp_irq(void *private)
271 {
272 	struct pp_struct *pp = private;
273 
274 	if (pp->irqresponse) {
275 		parport_write_control(pp->pdev->port, pp->irqctl);
276 		pp->irqresponse = 0;
277 	}
278 
279 	atomic_inc(&pp->irqc);
280 	wake_up_interruptible(&pp->irq_wait);
281 }
282 
283 static int register_device(int minor, struct pp_struct *pp)
284 {
285 	struct parport *port;
286 	struct pardevice *pdev = NULL;
287 	char *name;
288 	struct pardev_cb ppdev_cb;
289 	int rc = 0, index;
290 
291 	name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor);
292 	if (name == NULL)
293 		return -ENOMEM;
294 
295 	port = parport_find_number(minor);
296 	if (!port) {
297 		pr_warn("%s: no associated port!\n", name);
298 		rc = -ENXIO;
299 		goto err;
300 	}
301 
302 	index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
303 	memset(&ppdev_cb, 0, sizeof(ppdev_cb));
304 	ppdev_cb.irq_func = pp_irq;
305 	ppdev_cb.flags = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
306 	ppdev_cb.private = pp;
307 	pdev = parport_register_dev_model(port, name, &ppdev_cb, index);
308 	parport_put_port(port);
309 
310 	if (!pdev) {
311 		pr_warn("%s: failed to register device!\n", name);
312 		rc = -ENXIO;
313 		ida_simple_remove(&ida_index, index);
314 		goto err;
315 	}
316 
317 	pp->pdev = pdev;
318 	pp->index = index;
319 	dev_dbg(&pdev->dev, "registered pardevice\n");
320 err:
321 	kfree(name);
322 	return rc;
323 }
324 
325 static enum ieee1284_phase init_phase(int mode)
326 {
327 	switch (mode & ~(IEEE1284_DEVICEID
328 			 | IEEE1284_ADDR)) {
329 	case IEEE1284_MODE_NIBBLE:
330 	case IEEE1284_MODE_BYTE:
331 		return IEEE1284_PH_REV_IDLE;
332 	}
333 	return IEEE1284_PH_FWD_IDLE;
334 }
335 
336 static int pp_set_timeout(struct pardevice *pdev, long tv_sec, int tv_usec)
337 {
338 	long to_jiffies;
339 
340 	if ((tv_sec < 0) || (tv_usec < 0))
341 		return -EINVAL;
342 
343 	to_jiffies = usecs_to_jiffies(tv_usec);
344 	to_jiffies += tv_sec * HZ;
345 	if (to_jiffies <= 0)
346 		return -EINVAL;
347 
348 	pdev->timeout = to_jiffies;
349 	return 0;
350 }
351 
352 static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
353 {
354 	unsigned int minor = iminor(file_inode(file));
355 	struct pp_struct *pp = file->private_data;
356 	struct parport *port;
357 	void __user *argp = (void __user *)arg;
358 	struct ieee1284_info *info;
359 	unsigned char reg;
360 	unsigned char mask;
361 	int mode;
362 	s32 time32[2];
363 	s64 time64[2];
364 	struct timespec64 ts;
365 	int ret;
366 
367 	/* First handle the cases that don't take arguments. */
368 	switch (cmd) {
369 	case PPCLAIM:
370 	    {
371 		if (pp->flags & PP_CLAIMED) {
372 			dev_dbg(&pp->pdev->dev, "you've already got it!\n");
373 			return -EINVAL;
374 		}
375 
376 		/* Deferred device registration. */
377 		if (!pp->pdev) {
378 			int err = register_device(minor, pp);
379 
380 			if (err)
381 				return err;
382 		}
383 
384 		ret = parport_claim_or_block(pp->pdev);
385 		if (ret < 0)
386 			return ret;
387 
388 		pp->flags |= PP_CLAIMED;
389 
390 		/* For interrupt-reporting to work, we need to be
391 		 * informed of each interrupt. */
392 		pp_enable_irq(pp);
393 
394 		/* We may need to fix up the state machine. */
395 		info = &pp->pdev->port->ieee1284;
396 		pp->saved_state.mode = info->mode;
397 		pp->saved_state.phase = info->phase;
398 		info->mode = pp->state.mode;
399 		info->phase = pp->state.phase;
400 		pp->default_inactivity = parport_set_timeout(pp->pdev, 0);
401 		parport_set_timeout(pp->pdev, pp->default_inactivity);
402 
403 		return 0;
404 	    }
405 	case PPEXCL:
406 		if (pp->pdev) {
407 			dev_dbg(&pp->pdev->dev,
408 				"too late for PPEXCL; already registered\n");
409 			if (pp->flags & PP_EXCL)
410 				/* But it's not really an error. */
411 				return 0;
412 			/* There's no chance of making the driver happy. */
413 			return -EINVAL;
414 		}
415 
416 		/* Just remember to register the device exclusively
417 		 * when we finally do the registration. */
418 		pp->flags |= PP_EXCL;
419 		return 0;
420 	case PPSETMODE:
421 	    {
422 		int mode;
423 
424 		if (copy_from_user(&mode, argp, sizeof(mode)))
425 			return -EFAULT;
426 		/* FIXME: validate mode */
427 		pp->state.mode = mode;
428 		pp->state.phase = init_phase(mode);
429 
430 		if (pp->flags & PP_CLAIMED) {
431 			pp->pdev->port->ieee1284.mode = mode;
432 			pp->pdev->port->ieee1284.phase = pp->state.phase;
433 		}
434 
435 		return 0;
436 	    }
437 	case PPGETMODE:
438 	    {
439 		int mode;
440 
441 		if (pp->flags & PP_CLAIMED)
442 			mode = pp->pdev->port->ieee1284.mode;
443 		else
444 			mode = pp->state.mode;
445 
446 		if (copy_to_user(argp, &mode, sizeof(mode)))
447 			return -EFAULT;
448 		return 0;
449 	    }
450 	case PPSETPHASE:
451 	    {
452 		int phase;
453 
454 		if (copy_from_user(&phase, argp, sizeof(phase)))
455 			return -EFAULT;
456 
457 		/* FIXME: validate phase */
458 		pp->state.phase = phase;
459 
460 		if (pp->flags & PP_CLAIMED)
461 			pp->pdev->port->ieee1284.phase = phase;
462 
463 		return 0;
464 	    }
465 	case PPGETPHASE:
466 	    {
467 		int phase;
468 
469 		if (pp->flags & PP_CLAIMED)
470 			phase = pp->pdev->port->ieee1284.phase;
471 		else
472 			phase = pp->state.phase;
473 		if (copy_to_user(argp, &phase, sizeof(phase)))
474 			return -EFAULT;
475 		return 0;
476 	    }
477 	case PPGETMODES:
478 	    {
479 		unsigned int modes;
480 
481 		port = parport_find_number(minor);
482 		if (!port)
483 			return -ENODEV;
484 
485 		modes = port->modes;
486 		parport_put_port(port);
487 		if (copy_to_user(argp, &modes, sizeof(modes)))
488 			return -EFAULT;
489 		return 0;
490 	    }
491 	case PPSETFLAGS:
492 	    {
493 		int uflags;
494 
495 		if (copy_from_user(&uflags, argp, sizeof(uflags)))
496 			return -EFAULT;
497 		pp->flags &= ~PP_FLAGMASK;
498 		pp->flags |= (uflags & PP_FLAGMASK);
499 		return 0;
500 	    }
501 	case PPGETFLAGS:
502 	    {
503 		int uflags;
504 
505 		uflags = pp->flags & PP_FLAGMASK;
506 		if (copy_to_user(argp, &uflags, sizeof(uflags)))
507 			return -EFAULT;
508 		return 0;
509 	    }
510 	}	/* end switch() */
511 
512 	/* Everything else requires the port to be claimed, so check
513 	 * that now. */
514 	if ((pp->flags & PP_CLAIMED) == 0) {
515 		pr_debug(CHRDEV "%x: claim the port first\n", minor);
516 		return -EINVAL;
517 	}
518 
519 	port = pp->pdev->port;
520 	switch (cmd) {
521 	case PPRSTATUS:
522 		reg = parport_read_status(port);
523 		if (copy_to_user(argp, &reg, sizeof(reg)))
524 			return -EFAULT;
525 		return 0;
526 	case PPRDATA:
527 		reg = parport_read_data(port);
528 		if (copy_to_user(argp, &reg, sizeof(reg)))
529 			return -EFAULT;
530 		return 0;
531 	case PPRCONTROL:
532 		reg = parport_read_control(port);
533 		if (copy_to_user(argp, &reg, sizeof(reg)))
534 			return -EFAULT;
535 		return 0;
536 	case PPYIELD:
537 		parport_yield_blocking(pp->pdev);
538 		return 0;
539 
540 	case PPRELEASE:
541 		/* Save the state machine's state. */
542 		info = &pp->pdev->port->ieee1284;
543 		pp->state.mode = info->mode;
544 		pp->state.phase = info->phase;
545 		info->mode = pp->saved_state.mode;
546 		info->phase = pp->saved_state.phase;
547 		parport_release(pp->pdev);
548 		pp->flags &= ~PP_CLAIMED;
549 		return 0;
550 
551 	case PPWCONTROL:
552 		if (copy_from_user(&reg, argp, sizeof(reg)))
553 			return -EFAULT;
554 		parport_write_control(port, reg);
555 		return 0;
556 
557 	case PPWDATA:
558 		if (copy_from_user(&reg, argp, sizeof(reg)))
559 			return -EFAULT;
560 		parport_write_data(port, reg);
561 		return 0;
562 
563 	case PPFCONTROL:
564 		if (copy_from_user(&mask, argp,
565 				   sizeof(mask)))
566 			return -EFAULT;
567 		if (copy_from_user(&reg, 1 + (unsigned char __user *) arg,
568 				   sizeof(reg)))
569 			return -EFAULT;
570 		parport_frob_control(port, mask, reg);
571 		return 0;
572 
573 	case PPDATADIR:
574 		if (copy_from_user(&mode, argp, sizeof(mode)))
575 			return -EFAULT;
576 		if (mode)
577 			port->ops->data_reverse(port);
578 		else
579 			port->ops->data_forward(port);
580 		return 0;
581 
582 	case PPNEGOT:
583 		if (copy_from_user(&mode, argp, sizeof(mode)))
584 			return -EFAULT;
585 		switch ((ret = parport_negotiate(port, mode))) {
586 		case 0: break;
587 		case -1: /* handshake failed, peripheral not IEEE 1284 */
588 			ret = -EIO;
589 			break;
590 		case 1:  /* handshake succeeded, peripheral rejected mode */
591 			ret = -ENXIO;
592 			break;
593 		}
594 		pp_enable_irq(pp);
595 		return ret;
596 
597 	case PPWCTLONIRQ:
598 		if (copy_from_user(&reg, argp, sizeof(reg)))
599 			return -EFAULT;
600 
601 		/* Remember what to set the control lines to, for next
602 		 * time we get an interrupt. */
603 		pp->irqctl = reg;
604 		pp->irqresponse = 1;
605 		return 0;
606 
607 	case PPCLRIRQ:
608 		ret = atomic_read(&pp->irqc);
609 		if (copy_to_user(argp, &ret, sizeof(ret)))
610 			return -EFAULT;
611 		atomic_sub(ret, &pp->irqc);
612 		return 0;
613 
614 	case PPSETTIME32:
615 		if (copy_from_user(time32, argp, sizeof(time32)))
616 			return -EFAULT;
617 
618 		if ((time32[0] < 0) || (time32[1] < 0))
619 			return -EINVAL;
620 
621 		return pp_set_timeout(pp->pdev, time32[0], time32[1]);
622 
623 	case PPSETTIME64:
624 		if (copy_from_user(time64, argp, sizeof(time64)))
625 			return -EFAULT;
626 
627 		if ((time64[0] < 0) || (time64[1] < 0))
628 			return -EINVAL;
629 
630 		if (IS_ENABLED(CONFIG_SPARC64) && !in_compat_syscall())
631 			time64[1] >>= 32;
632 
633 		return pp_set_timeout(pp->pdev, time64[0], time64[1]);
634 
635 	case PPGETTIME32:
636 		jiffies_to_timespec64(pp->pdev->timeout, &ts);
637 		time32[0] = ts.tv_sec;
638 		time32[1] = ts.tv_nsec / NSEC_PER_USEC;
639 
640 		if (copy_to_user(argp, time32, sizeof(time32)))
641 			return -EFAULT;
642 
643 		return 0;
644 
645 	case PPGETTIME64:
646 		jiffies_to_timespec64(pp->pdev->timeout, &ts);
647 		time64[0] = ts.tv_sec;
648 		time64[1] = ts.tv_nsec / NSEC_PER_USEC;
649 
650 		if (IS_ENABLED(CONFIG_SPARC64) && !in_compat_syscall())
651 			time64[1] <<= 32;
652 
653 		if (copy_to_user(argp, time64, sizeof(time64)))
654 			return -EFAULT;
655 
656 		return 0;
657 
658 	default:
659 		dev_dbg(&pp->pdev->dev, "What? (cmd=0x%x)\n", cmd);
660 		return -EINVAL;
661 	}
662 
663 	/* Keep the compiler happy */
664 	return 0;
665 }
666 
667 static long pp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
668 {
669 	long ret;
670 
671 	mutex_lock(&pp_do_mutex);
672 	ret = pp_do_ioctl(file, cmd, arg);
673 	mutex_unlock(&pp_do_mutex);
674 	return ret;
675 }
676 
677 static int pp_open(struct inode *inode, struct file *file)
678 {
679 	unsigned int minor = iminor(inode);
680 	struct pp_struct *pp;
681 
682 	if (minor >= PARPORT_MAX)
683 		return -ENXIO;
684 
685 	pp = kmalloc(sizeof(struct pp_struct), GFP_KERNEL);
686 	if (!pp)
687 		return -ENOMEM;
688 
689 	pp->state.mode = IEEE1284_MODE_COMPAT;
690 	pp->state.phase = init_phase(pp->state.mode);
691 	pp->flags = 0;
692 	pp->irqresponse = 0;
693 	atomic_set(&pp->irqc, 0);
694 	init_waitqueue_head(&pp->irq_wait);
695 
696 	/* Defer the actual device registration until the first claim.
697 	 * That way, we know whether or not the driver wants to have
698 	 * exclusive access to the port (PPEXCL).
699 	 */
700 	pp->pdev = NULL;
701 	file->private_data = pp;
702 
703 	return 0;
704 }
705 
706 static int pp_release(struct inode *inode, struct file *file)
707 {
708 	unsigned int minor = iminor(inode);
709 	struct pp_struct *pp = file->private_data;
710 	int compat_negot;
711 
712 	compat_negot = 0;
713 	if (!(pp->flags & PP_CLAIMED) && pp->pdev &&
714 	    (pp->state.mode != IEEE1284_MODE_COMPAT)) {
715 		struct ieee1284_info *info;
716 
717 		/* parport released, but not in compatibility mode */
718 		parport_claim_or_block(pp->pdev);
719 		pp->flags |= PP_CLAIMED;
720 		info = &pp->pdev->port->ieee1284;
721 		pp->saved_state.mode = info->mode;
722 		pp->saved_state.phase = info->phase;
723 		info->mode = pp->state.mode;
724 		info->phase = pp->state.phase;
725 		compat_negot = 1;
726 	} else if ((pp->flags & PP_CLAIMED) && pp->pdev &&
727 	    (pp->pdev->port->ieee1284.mode != IEEE1284_MODE_COMPAT)) {
728 		compat_negot = 2;
729 	}
730 	if (compat_negot) {
731 		parport_negotiate(pp->pdev->port, IEEE1284_MODE_COMPAT);
732 		dev_dbg(&pp->pdev->dev,
733 			"negotiated back to compatibility mode because user-space forgot\n");
734 	}
735 
736 	if ((pp->flags & PP_CLAIMED) && pp->pdev) {
737 		struct ieee1284_info *info;
738 
739 		info = &pp->pdev->port->ieee1284;
740 		pp->state.mode = info->mode;
741 		pp->state.phase = info->phase;
742 		info->mode = pp->saved_state.mode;
743 		info->phase = pp->saved_state.phase;
744 		parport_release(pp->pdev);
745 		if (compat_negot != 1) {
746 			pr_debug(CHRDEV "%x: released pardevice "
747 				"because user-space forgot\n", minor);
748 		}
749 	}
750 
751 	if (pp->pdev) {
752 		parport_unregister_device(pp->pdev);
753 		ida_simple_remove(&ida_index, pp->index);
754 		pp->pdev = NULL;
755 		pr_debug(CHRDEV "%x: unregistered pardevice\n", minor);
756 	}
757 
758 	kfree(pp);
759 
760 	return 0;
761 }
762 
763 /* No kernel lock held - fine */
764 static __poll_t pp_poll(struct file *file, poll_table *wait)
765 {
766 	struct pp_struct *pp = file->private_data;
767 	__poll_t mask = 0;
768 
769 	poll_wait(file, &pp->irq_wait, wait);
770 	if (atomic_read(&pp->irqc))
771 		mask |= EPOLLIN | EPOLLRDNORM;
772 
773 	return mask;
774 }
775 
776 static struct class *ppdev_class;
777 
778 static const struct file_operations pp_fops = {
779 	.owner		= THIS_MODULE,
780 	.llseek		= no_llseek,
781 	.read		= pp_read,
782 	.write		= pp_write,
783 	.poll		= pp_poll,
784 	.unlocked_ioctl	= pp_ioctl,
785 	.compat_ioctl   = compat_ptr_ioctl,
786 	.open		= pp_open,
787 	.release	= pp_release,
788 };
789 
790 static void pp_attach(struct parport *port)
791 {
792 	struct device *ret;
793 
794 	if (devices[port->number])
795 		return;
796 
797 	ret = device_create(ppdev_class, port->dev,
798 			    MKDEV(PP_MAJOR, port->number), NULL,
799 			    "parport%d", port->number);
800 	if (IS_ERR(ret)) {
801 		pr_err("Failed to create device parport%d\n",
802 		       port->number);
803 		return;
804 	}
805 	devices[port->number] = ret;
806 }
807 
808 static void pp_detach(struct parport *port)
809 {
810 	if (!devices[port->number])
811 		return;
812 
813 	device_destroy(ppdev_class, MKDEV(PP_MAJOR, port->number));
814 	devices[port->number] = NULL;
815 }
816 
817 static int pp_probe(struct pardevice *par_dev)
818 {
819 	struct device_driver *drv = par_dev->dev.driver;
820 	int len = strlen(drv->name);
821 
822 	if (strncmp(par_dev->name, drv->name, len))
823 		return -ENODEV;
824 
825 	return 0;
826 }
827 
828 static struct parport_driver pp_driver = {
829 	.name		= CHRDEV,
830 	.probe		= pp_probe,
831 	.match_port	= pp_attach,
832 	.detach		= pp_detach,
833 	.devmodel	= true,
834 };
835 
836 static int __init ppdev_init(void)
837 {
838 	int err = 0;
839 
840 	if (register_chrdev(PP_MAJOR, CHRDEV, &pp_fops)) {
841 		pr_warn(CHRDEV ": unable to get major %d\n", PP_MAJOR);
842 		return -EIO;
843 	}
844 	ppdev_class = class_create(CHRDEV);
845 	if (IS_ERR(ppdev_class)) {
846 		err = PTR_ERR(ppdev_class);
847 		goto out_chrdev;
848 	}
849 	err = parport_register_driver(&pp_driver);
850 	if (err < 0) {
851 		pr_warn(CHRDEV ": unable to register with parport\n");
852 		goto out_class;
853 	}
854 
855 	pr_info(PP_VERSION "\n");
856 	goto out;
857 
858 out_class:
859 	class_destroy(ppdev_class);
860 out_chrdev:
861 	unregister_chrdev(PP_MAJOR, CHRDEV);
862 out:
863 	return err;
864 }
865 
866 static void __exit ppdev_cleanup(void)
867 {
868 	/* Clean up all parport stuff */
869 	parport_unregister_driver(&pp_driver);
870 	class_destroy(ppdev_class);
871 	unregister_chrdev(PP_MAJOR, CHRDEV);
872 }
873 
874 module_init(ppdev_init);
875 module_exit(ppdev_cleanup);
876 
877 MODULE_LICENSE("GPL");
878 MODULE_ALIAS_CHARDEV_MAJOR(PP_MAJOR);
879