xref: /openbmc/linux/drivers/macintosh/adb.c (revision afb46f79)
1 /*
2  * Device driver for the Apple Desktop Bus
3  * and the /dev/adb device on macintoshes.
4  *
5  * Copyright (C) 1996 Paul Mackerras.
6  *
7  * Modified to declare controllers as structures, added
8  * client notification of bus reset and handles PowerBook
9  * sleep, by Benjamin Herrenschmidt.
10  *
11  * To do:
12  *
13  * - /sys/bus/adb to list the devices and infos
14  * - more /dev/adb to allow userland to receive the
15  *   flow of auto-polling datas from a given device.
16  * - move bus probe to a kernel thread
17  */
18 
19 #include <linux/types.h>
20 #include <linux/errno.h>
21 #include <linux/kernel.h>
22 #include <linux/slab.h>
23 #include <linux/module.h>
24 #include <linux/fs.h>
25 #include <linux/mm.h>
26 #include <linux/sched.h>
27 #include <linux/adb.h>
28 #include <linux/cuda.h>
29 #include <linux/pmu.h>
30 #include <linux/notifier.h>
31 #include <linux/wait.h>
32 #include <linux/init.h>
33 #include <linux/delay.h>
34 #include <linux/spinlock.h>
35 #include <linux/completion.h>
36 #include <linux/device.h>
37 #include <linux/kthread.h>
38 #include <linux/platform_device.h>
39 #include <linux/mutex.h>
40 
41 #include <linux/uaccess.h>
42 #ifdef CONFIG_PPC
43 #include <asm/prom.h>
44 #include <asm/machdep.h>
45 #endif
46 
47 
48 EXPORT_SYMBOL(adb_client_list);
49 
50 extern struct adb_driver via_macii_driver;
51 extern struct adb_driver via_maciisi_driver;
52 extern struct adb_driver via_cuda_driver;
53 extern struct adb_driver adb_iop_driver;
54 extern struct adb_driver via_pmu_driver;
55 extern struct adb_driver macio_adb_driver;
56 
57 static DEFINE_MUTEX(adb_mutex);
58 static struct adb_driver *adb_driver_list[] = {
59 #ifdef CONFIG_ADB_MACII
60 	&via_macii_driver,
61 #endif
62 #ifdef CONFIG_ADB_MACIISI
63 	&via_maciisi_driver,
64 #endif
65 #ifdef CONFIG_ADB_CUDA
66 	&via_cuda_driver,
67 #endif
68 #ifdef CONFIG_ADB_IOP
69 	&adb_iop_driver,
70 #endif
71 #if defined(CONFIG_ADB_PMU) || defined(CONFIG_ADB_PMU68K)
72 	&via_pmu_driver,
73 #endif
74 #ifdef CONFIG_ADB_MACIO
75 	&macio_adb_driver,
76 #endif
77 	NULL
78 };
79 
80 static struct class *adb_dev_class;
81 
82 static struct adb_driver *adb_controller;
83 BLOCKING_NOTIFIER_HEAD(adb_client_list);
84 static int adb_got_sleep;
85 static int adb_inited;
86 static DEFINE_SEMAPHORE(adb_probe_mutex);
87 static int sleepy_trackpad;
88 static int autopoll_devs;
89 int __adb_probe_sync;
90 
91 static int adb_scan_bus(void);
92 static int do_adb_reset_bus(void);
93 static void adbdev_init(void);
94 static int try_handler_change(int, int);
95 
96 static struct adb_handler {
97 	void (*handler)(unsigned char *, int, int);
98 	int original_address;
99 	int handler_id;
100 	int busy;
101 } adb_handler[16];
102 
103 /*
104  * The adb_handler_mutex mutex protects all accesses to the original_address
105  * and handler_id fields of adb_handler[i] for all i, and changes to the
106  * handler field.
107  * Accesses to the handler field are protected by the adb_handler_lock
108  * rwlock.  It is held across all calls to any handler, so that by the
109  * time adb_unregister returns, we know that the old handler isn't being
110  * called.
111  */
112 static DEFINE_MUTEX(adb_handler_mutex);
113 static DEFINE_RWLOCK(adb_handler_lock);
114 
115 #if 0
116 static void printADBreply(struct adb_request *req)
117 {
118         int i;
119 
120         printk("adb reply (%d)", req->reply_len);
121         for(i = 0; i < req->reply_len; i++)
122                 printk(" %x", req->reply[i]);
123         printk("\n");
124 
125 }
126 #endif
127 
128 static int adb_scan_bus(void)
129 {
130 	int i, highFree=0, noMovement;
131 	int devmask = 0;
132 	struct adb_request req;
133 
134 	/* assumes adb_handler[] is all zeroes at this point */
135 	for (i = 1; i < 16; i++) {
136 		/* see if there is anything at address i */
137 		adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
138                             (i << 4) | 0xf);
139 		if (req.reply_len > 1)
140 			/* one or more devices at this address */
141 			adb_handler[i].original_address = i;
142 		else if (i > highFree)
143 			highFree = i;
144 	}
145 
146 	/* Note we reset noMovement to 0 each time we move a device */
147 	for (noMovement = 1; noMovement < 2 && highFree > 0; noMovement++) {
148 		for (i = 1; i < 16; i++) {
149 			if (adb_handler[i].original_address == 0)
150 				continue;
151 			/*
152 			 * Send a "talk register 3" command to address i
153 			 * to provoke a collision if there is more than
154 			 * one device at this address.
155 			 */
156 			adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
157 				    (i << 4) | 0xf);
158 			/*
159 			 * Move the device(s) which didn't detect a
160 			 * collision to address `highFree'.  Hopefully
161 			 * this only moves one device.
162 			 */
163 			adb_request(&req, NULL, ADBREQ_SYNC, 3,
164 				    (i<< 4) | 0xb, (highFree | 0x60), 0xfe);
165 			/*
166 			 * See if anybody actually moved. This is suggested
167 			 * by HW TechNote 01:
168 			 *
169 			 * http://developer.apple.com/technotes/hw/hw_01.html
170 			 */
171 			adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
172 				    (highFree << 4) | 0xf);
173 			if (req.reply_len <= 1) continue;
174 			/*
175 			 * Test whether there are any device(s) left
176 			 * at address i.
177 			 */
178 			adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
179 				    (i << 4) | 0xf);
180 			if (req.reply_len > 1) {
181 				/*
182 				 * There are still one or more devices
183 				 * left at address i.  Register the one(s)
184 				 * we moved to `highFree', and find a new
185 				 * value for highFree.
186 				 */
187 				adb_handler[highFree].original_address =
188 					adb_handler[i].original_address;
189 				while (highFree > 0 &&
190 				       adb_handler[highFree].original_address)
191 					highFree--;
192 				if (highFree <= 0)
193 					break;
194 
195 				noMovement = 0;
196 			} else {
197 				/*
198 				 * No devices left at address i; move the
199 				 * one(s) we moved to `highFree' back to i.
200 				 */
201 				adb_request(&req, NULL, ADBREQ_SYNC, 3,
202 					    (highFree << 4) | 0xb,
203 					    (i | 0x60), 0xfe);
204 			}
205 		}
206 	}
207 
208 	/* Now fill in the handler_id field of the adb_handler entries. */
209 	printk(KERN_DEBUG "adb devices:");
210 	for (i = 1; i < 16; i++) {
211 		if (adb_handler[i].original_address == 0)
212 			continue;
213 		adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
214 			    (i << 4) | 0xf);
215 		adb_handler[i].handler_id = req.reply[2];
216 		printk(" [%d]: %d %x", i, adb_handler[i].original_address,
217 		       adb_handler[i].handler_id);
218 		devmask |= 1 << i;
219 	}
220 	printk("\n");
221 	return devmask;
222 }
223 
224 /*
225  * This kernel task handles ADB probing. It dies once probing is
226  * completed.
227  */
228 static int
229 adb_probe_task(void *x)
230 {
231 	printk(KERN_INFO "adb: starting probe task...\n");
232 	do_adb_reset_bus();
233 	printk(KERN_INFO "adb: finished probe task...\n");
234 
235 	up(&adb_probe_mutex);
236 
237 	return 0;
238 }
239 
240 static void
241 __adb_probe_task(struct work_struct *bullshit)
242 {
243 	kthread_run(adb_probe_task, NULL, "kadbprobe");
244 }
245 
246 static DECLARE_WORK(adb_reset_work, __adb_probe_task);
247 
248 int
249 adb_reset_bus(void)
250 {
251 	if (__adb_probe_sync) {
252 		do_adb_reset_bus();
253 		return 0;
254 	}
255 
256 	down(&adb_probe_mutex);
257 	schedule_work(&adb_reset_work);
258 	return 0;
259 }
260 
261 #ifdef CONFIG_PM
262 /*
263  * notify clients before sleep
264  */
265 static int __adb_suspend(struct platform_device *dev, pm_message_t state)
266 {
267 	adb_got_sleep = 1;
268 	/* We need to get a lock on the probe thread */
269 	down(&adb_probe_mutex);
270 	/* Stop autopoll */
271 	if (adb_controller->autopoll)
272 		adb_controller->autopoll(0);
273 	blocking_notifier_call_chain(&adb_client_list, ADB_MSG_POWERDOWN, NULL);
274 
275 	return 0;
276 }
277 
278 static int adb_suspend(struct device *dev)
279 {
280 	return __adb_suspend(to_platform_device(dev), PMSG_SUSPEND);
281 }
282 
283 static int adb_freeze(struct device *dev)
284 {
285 	return __adb_suspend(to_platform_device(dev), PMSG_FREEZE);
286 }
287 
288 static int adb_poweroff(struct device *dev)
289 {
290 	return __adb_suspend(to_platform_device(dev), PMSG_HIBERNATE);
291 }
292 
293 /*
294  * reset bus after sleep
295  */
296 static int __adb_resume(struct platform_device *dev)
297 {
298 	adb_got_sleep = 0;
299 	up(&adb_probe_mutex);
300 	adb_reset_bus();
301 
302 	return 0;
303 }
304 
305 static int adb_resume(struct device *dev)
306 {
307 	return __adb_resume(to_platform_device(dev));
308 }
309 #endif /* CONFIG_PM */
310 
311 static int __init adb_init(void)
312 {
313 	struct adb_driver *driver;
314 	int i;
315 
316 #ifdef CONFIG_PPC32
317 	if (!machine_is(chrp) && !machine_is(powermac))
318 		return 0;
319 #endif
320 #ifdef CONFIG_MAC
321 	if (!MACH_IS_MAC)
322 		return 0;
323 #endif
324 
325 	/* xmon may do early-init */
326 	if (adb_inited)
327 		return 0;
328 	adb_inited = 1;
329 
330 	adb_controller = NULL;
331 
332 	i = 0;
333 	while ((driver = adb_driver_list[i++]) != NULL) {
334 		if (!driver->probe()) {
335 			adb_controller = driver;
336 			break;
337 		}
338 	}
339 	if (adb_controller != NULL && adb_controller->init &&
340 	    adb_controller->init())
341 		adb_controller = NULL;
342 	if (adb_controller == NULL) {
343 		printk(KERN_WARNING "Warning: no ADB interface detected\n");
344 	} else {
345 #ifdef CONFIG_PPC
346 		if (of_machine_is_compatible("AAPL,PowerBook1998") ||
347 			of_machine_is_compatible("PowerBook1,1"))
348 			sleepy_trackpad = 1;
349 #endif /* CONFIG_PPC */
350 
351 		adbdev_init();
352 		adb_reset_bus();
353 	}
354 	return 0;
355 }
356 
357 device_initcall(adb_init);
358 
359 static int
360 do_adb_reset_bus(void)
361 {
362 	int ret;
363 
364 	if (adb_controller == NULL)
365 		return -ENXIO;
366 
367 	if (adb_controller->autopoll)
368 		adb_controller->autopoll(0);
369 
370 	blocking_notifier_call_chain(&adb_client_list,
371 		ADB_MSG_PRE_RESET, NULL);
372 
373 	if (sleepy_trackpad) {
374 		/* Let the trackpad settle down */
375 		msleep(500);
376 	}
377 
378 	mutex_lock(&adb_handler_mutex);
379 	write_lock_irq(&adb_handler_lock);
380 	memset(adb_handler, 0, sizeof(adb_handler));
381 	write_unlock_irq(&adb_handler_lock);
382 
383 	/* That one is still a bit synchronous, oh well... */
384 	if (adb_controller->reset_bus)
385 		ret = adb_controller->reset_bus();
386 	else
387 		ret = 0;
388 
389 	if (sleepy_trackpad) {
390 		/* Let the trackpad settle down */
391 		msleep(1500);
392 	}
393 
394 	if (!ret) {
395 		autopoll_devs = adb_scan_bus();
396 		if (adb_controller->autopoll)
397 			adb_controller->autopoll(autopoll_devs);
398 	}
399 	mutex_unlock(&adb_handler_mutex);
400 
401 	blocking_notifier_call_chain(&adb_client_list,
402 		ADB_MSG_POST_RESET, NULL);
403 
404 	return ret;
405 }
406 
407 void
408 adb_poll(void)
409 {
410 	if ((adb_controller == NULL)||(adb_controller->poll == NULL))
411 		return;
412 	adb_controller->poll();
413 }
414 
415 static void adb_sync_req_done(struct adb_request *req)
416 {
417 	struct completion *comp = req->arg;
418 
419 	complete(comp);
420 }
421 
422 int
423 adb_request(struct adb_request *req, void (*done)(struct adb_request *),
424 	    int flags, int nbytes, ...)
425 {
426 	va_list list;
427 	int i;
428 	int rc;
429 	struct completion comp;
430 
431 	if ((adb_controller == NULL) || (adb_controller->send_request == NULL))
432 		return -ENXIO;
433 	if (nbytes < 1)
434 		return -EINVAL;
435 
436 	req->nbytes = nbytes+1;
437 	req->done = done;
438 	req->reply_expected = flags & ADBREQ_REPLY;
439 	req->data[0] = ADB_PACKET;
440 	va_start(list, nbytes);
441 	for (i = 0; i < nbytes; ++i)
442 		req->data[i+1] = va_arg(list, int);
443 	va_end(list);
444 
445 	if (flags & ADBREQ_NOSEND)
446 		return 0;
447 
448 	/* Synchronous requests block using an on-stack completion */
449 	if (flags & ADBREQ_SYNC) {
450 		WARN_ON(done);
451 		req->done = adb_sync_req_done;
452 		req->arg = &comp;
453 		init_completion(&comp);
454 	}
455 
456 	rc = adb_controller->send_request(req, 0);
457 
458 	if ((flags & ADBREQ_SYNC) && !rc && !req->complete)
459 		wait_for_completion(&comp);
460 
461 	return rc;
462 }
463 
464  /* Ultimately this should return the number of devices with
465     the given default id.
466     And it does it now ! Note: changed behaviour: This function
467     will now register if default_id _and_ handler_id both match
468     but handler_id can be left to 0 to match with default_id only.
469     When handler_id is set, this function will try to adjust
470     the handler_id id it doesn't match. */
471 int
472 adb_register(int default_id, int handler_id, struct adb_ids *ids,
473 	     void (*handler)(unsigned char *, int, int))
474 {
475 	int i;
476 
477 	mutex_lock(&adb_handler_mutex);
478 	ids->nids = 0;
479 	for (i = 1; i < 16; i++) {
480 		if ((adb_handler[i].original_address == default_id) &&
481 		    (!handler_id || (handler_id == adb_handler[i].handler_id) ||
482 		    try_handler_change(i, handler_id))) {
483 			if (adb_handler[i].handler != 0) {
484 				printk(KERN_ERR
485 				       "Two handlers for ADB device %d\n",
486 				       default_id);
487 				continue;
488 			}
489 			write_lock_irq(&adb_handler_lock);
490 			adb_handler[i].handler = handler;
491 			write_unlock_irq(&adb_handler_lock);
492 			ids->id[ids->nids++] = i;
493 		}
494 	}
495 	mutex_unlock(&adb_handler_mutex);
496 	return ids->nids;
497 }
498 
499 int
500 adb_unregister(int index)
501 {
502 	int ret = -ENODEV;
503 
504 	mutex_lock(&adb_handler_mutex);
505 	write_lock_irq(&adb_handler_lock);
506 	if (adb_handler[index].handler) {
507 		while(adb_handler[index].busy) {
508 			write_unlock_irq(&adb_handler_lock);
509 			yield();
510 			write_lock_irq(&adb_handler_lock);
511 		}
512 		ret = 0;
513 		adb_handler[index].handler = NULL;
514 	}
515 	write_unlock_irq(&adb_handler_lock);
516 	mutex_unlock(&adb_handler_mutex);
517 	return ret;
518 }
519 
520 void
521 adb_input(unsigned char *buf, int nb, int autopoll)
522 {
523 	int i, id;
524 	static int dump_adb_input;
525 	unsigned long flags;
526 
527 	void (*handler)(unsigned char *, int, int);
528 
529 	/* We skip keystrokes and mouse moves when the sleep process
530 	 * has been started. We stop autopoll, but this is another security
531 	 */
532 	if (adb_got_sleep)
533 		return;
534 
535 	id = buf[0] >> 4;
536 	if (dump_adb_input) {
537 		printk(KERN_INFO "adb packet: ");
538 		for (i = 0; i < nb; ++i)
539 			printk(" %x", buf[i]);
540 		printk(", id = %d\n", id);
541 	}
542 	write_lock_irqsave(&adb_handler_lock, flags);
543 	handler = adb_handler[id].handler;
544 	if (handler != NULL)
545 		adb_handler[id].busy = 1;
546 	write_unlock_irqrestore(&adb_handler_lock, flags);
547 	if (handler != NULL) {
548 		(*handler)(buf, nb, autopoll);
549 		wmb();
550 		adb_handler[id].busy = 0;
551 	}
552 
553 }
554 
555 /* Try to change handler to new_id. Will return 1 if successful. */
556 static int try_handler_change(int address, int new_id)
557 {
558 	struct adb_request req;
559 
560 	if (adb_handler[address].handler_id == new_id)
561 	    return 1;
562 	adb_request(&req, NULL, ADBREQ_SYNC, 3,
563 	    ADB_WRITEREG(address, 3), address | 0x20, new_id);
564 	adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
565 	    ADB_READREG(address, 3));
566 	if (req.reply_len < 2)
567 	    return 0;
568 	if (req.reply[2] != new_id)
569 	    return 0;
570 	adb_handler[address].handler_id = req.reply[2];
571 
572 	return 1;
573 }
574 
575 int
576 adb_try_handler_change(int address, int new_id)
577 {
578 	int ret;
579 
580 	mutex_lock(&adb_handler_mutex);
581 	ret = try_handler_change(address, new_id);
582 	mutex_unlock(&adb_handler_mutex);
583 	return ret;
584 }
585 
586 int
587 adb_get_infos(int address, int *original_address, int *handler_id)
588 {
589 	mutex_lock(&adb_handler_mutex);
590 	*original_address = adb_handler[address].original_address;
591 	*handler_id = adb_handler[address].handler_id;
592 	mutex_unlock(&adb_handler_mutex);
593 
594 	return (*original_address != 0);
595 }
596 
597 
598 /*
599  * /dev/adb device driver.
600  */
601 
602 #define ADB_MAJOR	56	/* major number for /dev/adb */
603 
604 struct adbdev_state {
605 	spinlock_t	lock;
606 	atomic_t	n_pending;
607 	struct adb_request *completed;
608   	wait_queue_head_t wait_queue;
609 	int		inuse;
610 };
611 
612 static void adb_write_done(struct adb_request *req)
613 {
614 	struct adbdev_state *state = (struct adbdev_state *) req->arg;
615 	unsigned long flags;
616 
617 	if (!req->complete) {
618 		req->reply_len = 0;
619 		req->complete = 1;
620 	}
621 	spin_lock_irqsave(&state->lock, flags);
622 	atomic_dec(&state->n_pending);
623 	if (!state->inuse) {
624 		kfree(req);
625 		if (atomic_read(&state->n_pending) == 0) {
626 			spin_unlock_irqrestore(&state->lock, flags);
627 			kfree(state);
628 			return;
629 		}
630 	} else {
631 		struct adb_request **ap = &state->completed;
632 		while (*ap != NULL)
633 			ap = &(*ap)->next;
634 		req->next = NULL;
635 		*ap = req;
636 		wake_up_interruptible(&state->wait_queue);
637 	}
638 	spin_unlock_irqrestore(&state->lock, flags);
639 }
640 
641 static int
642 do_adb_query(struct adb_request *req)
643 {
644 	int	ret = -EINVAL;
645 
646 	switch(req->data[1]) {
647 	case ADB_QUERY_GETDEVINFO:
648 		if (req->nbytes < 3)
649 			break;
650 		mutex_lock(&adb_handler_mutex);
651 		req->reply[0] = adb_handler[req->data[2]].original_address;
652 		req->reply[1] = adb_handler[req->data[2]].handler_id;
653 		mutex_unlock(&adb_handler_mutex);
654 		req->complete = 1;
655 		req->reply_len = 2;
656 		adb_write_done(req);
657 		ret = 0;
658 		break;
659 	}
660 	return ret;
661 }
662 
663 static int adb_open(struct inode *inode, struct file *file)
664 {
665 	struct adbdev_state *state;
666 	int ret = 0;
667 
668 	mutex_lock(&adb_mutex);
669 	if (iminor(inode) > 0 || adb_controller == NULL) {
670 		ret = -ENXIO;
671 		goto out;
672 	}
673 	state = kmalloc(sizeof(struct adbdev_state), GFP_KERNEL);
674 	if (state == 0) {
675 		ret = -ENOMEM;
676 		goto out;
677 	}
678 	file->private_data = state;
679 	spin_lock_init(&state->lock);
680 	atomic_set(&state->n_pending, 0);
681 	state->completed = NULL;
682 	init_waitqueue_head(&state->wait_queue);
683 	state->inuse = 1;
684 
685 out:
686 	mutex_unlock(&adb_mutex);
687 	return ret;
688 }
689 
690 static int adb_release(struct inode *inode, struct file *file)
691 {
692 	struct adbdev_state *state = file->private_data;
693 	unsigned long flags;
694 
695 	mutex_lock(&adb_mutex);
696 	if (state) {
697 		file->private_data = NULL;
698 		spin_lock_irqsave(&state->lock, flags);
699 		if (atomic_read(&state->n_pending) == 0
700 		    && state->completed == NULL) {
701 			spin_unlock_irqrestore(&state->lock, flags);
702 			kfree(state);
703 		} else {
704 			state->inuse = 0;
705 			spin_unlock_irqrestore(&state->lock, flags);
706 		}
707 	}
708 	mutex_unlock(&adb_mutex);
709 	return 0;
710 }
711 
712 static ssize_t adb_read(struct file *file, char __user *buf,
713 			size_t count, loff_t *ppos)
714 {
715 	int ret = 0;
716 	struct adbdev_state *state = file->private_data;
717 	struct adb_request *req;
718 	DECLARE_WAITQUEUE(wait, current);
719 	unsigned long flags;
720 
721 	if (count < 2)
722 		return -EINVAL;
723 	if (count > sizeof(req->reply))
724 		count = sizeof(req->reply);
725 	if (!access_ok(VERIFY_WRITE, buf, count))
726 		return -EFAULT;
727 
728 	req = NULL;
729 	spin_lock_irqsave(&state->lock, flags);
730 	add_wait_queue(&state->wait_queue, &wait);
731 	set_current_state(TASK_INTERRUPTIBLE);
732 
733 	for (;;) {
734 		req = state->completed;
735 		if (req != NULL)
736 			state->completed = req->next;
737 		else if (atomic_read(&state->n_pending) == 0)
738 			ret = -EIO;
739 		if (req != NULL || ret != 0)
740 			break;
741 
742 		if (file->f_flags & O_NONBLOCK) {
743 			ret = -EAGAIN;
744 			break;
745 		}
746 		if (signal_pending(current)) {
747 			ret = -ERESTARTSYS;
748 			break;
749 		}
750 		spin_unlock_irqrestore(&state->lock, flags);
751 		schedule();
752 		spin_lock_irqsave(&state->lock, flags);
753 	}
754 
755 	set_current_state(TASK_RUNNING);
756 	remove_wait_queue(&state->wait_queue, &wait);
757 	spin_unlock_irqrestore(&state->lock, flags);
758 
759 	if (ret)
760 		return ret;
761 
762 	ret = req->reply_len;
763 	if (ret > count)
764 		ret = count;
765 	if (ret > 0 && copy_to_user(buf, req->reply, ret))
766 		ret = -EFAULT;
767 
768 	kfree(req);
769 	return ret;
770 }
771 
772 static ssize_t adb_write(struct file *file, const char __user *buf,
773 			 size_t count, loff_t *ppos)
774 {
775 	int ret/*, i*/;
776 	struct adbdev_state *state = file->private_data;
777 	struct adb_request *req;
778 
779 	if (count < 2 || count > sizeof(req->data))
780 		return -EINVAL;
781 	if (adb_controller == NULL)
782 		return -ENXIO;
783 	if (!access_ok(VERIFY_READ, buf, count))
784 		return -EFAULT;
785 
786 	req = kmalloc(sizeof(struct adb_request),
787 					     GFP_KERNEL);
788 	if (req == NULL)
789 		return -ENOMEM;
790 
791 	req->nbytes = count;
792 	req->done = adb_write_done;
793 	req->arg = (void *) state;
794 	req->complete = 0;
795 
796 	ret = -EFAULT;
797 	if (copy_from_user(req->data, buf, count))
798 		goto out;
799 
800 	atomic_inc(&state->n_pending);
801 
802 	/* If a probe is in progress or we are sleeping, wait for it to complete */
803 	down(&adb_probe_mutex);
804 
805 	/* Queries are special requests sent to the ADB driver itself */
806 	if (req->data[0] == ADB_QUERY) {
807 		if (count > 1)
808 			ret = do_adb_query(req);
809 		else
810 			ret = -EINVAL;
811 		up(&adb_probe_mutex);
812 	}
813 	/* Special case for ADB_BUSRESET request, all others are sent to
814 	   the controller */
815 	else if ((req->data[0] == ADB_PACKET) && (count > 1)
816 		&& (req->data[1] == ADB_BUSRESET)) {
817 		ret = do_adb_reset_bus();
818 		up(&adb_probe_mutex);
819 		atomic_dec(&state->n_pending);
820 		if (ret == 0)
821 			ret = count;
822 		goto out;
823 	} else {
824 		req->reply_expected = ((req->data[1] & 0xc) == 0xc);
825 		if (adb_controller && adb_controller->send_request)
826 			ret = adb_controller->send_request(req, 0);
827 		else
828 			ret = -ENXIO;
829 		up(&adb_probe_mutex);
830 	}
831 
832 	if (ret != 0) {
833 		atomic_dec(&state->n_pending);
834 		goto out;
835 	}
836 	return count;
837 
838 out:
839 	kfree(req);
840 	return ret;
841 }
842 
843 static const struct file_operations adb_fops = {
844 	.owner		= THIS_MODULE,
845 	.llseek		= no_llseek,
846 	.read		= adb_read,
847 	.write		= adb_write,
848 	.open		= adb_open,
849 	.release	= adb_release,
850 };
851 
852 #ifdef CONFIG_PM
853 static const struct dev_pm_ops adb_dev_pm_ops = {
854 	.suspend = adb_suspend,
855 	.resume = adb_resume,
856 	/* Hibernate hooks */
857 	.freeze = adb_freeze,
858 	.thaw = adb_resume,
859 	.poweroff = adb_poweroff,
860 	.restore = adb_resume,
861 };
862 #endif
863 
864 static struct platform_driver adb_pfdrv = {
865 	.driver = {
866 		.name = "adb",
867 #ifdef CONFIG_PM
868 		.pm = &adb_dev_pm_ops,
869 #endif
870 	},
871 };
872 
873 static struct platform_device adb_pfdev = {
874 	.name = "adb",
875 };
876 
877 static int __init
878 adb_dummy_probe(struct platform_device *dev)
879 {
880 	if (dev == &adb_pfdev)
881 		return 0;
882 	return -ENODEV;
883 }
884 
885 static void __init
886 adbdev_init(void)
887 {
888 	if (register_chrdev(ADB_MAJOR, "adb", &adb_fops)) {
889 		printk(KERN_ERR "adb: unable to get major %d\n", ADB_MAJOR);
890 		return;
891 	}
892 
893 	adb_dev_class = class_create(THIS_MODULE, "adb");
894 	if (IS_ERR(adb_dev_class))
895 		return;
896 	device_create(adb_dev_class, NULL, MKDEV(ADB_MAJOR, 0), NULL, "adb");
897 
898 	platform_device_register(&adb_pfdev);
899 	platform_driver_probe(&adb_pfdrv, adb_dummy_probe);
900 }
901