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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* $Id: parport_share.c,v 1.15 1998/01/11 12:06:17 philip Exp $
2 * Parallel-port resource manager code.
3 *
4 * Authors: David Campbell <campbell@tirian.che.curtin.edu.au>
5 * Tim Waugh <tim@cyberelk.demon.co.uk>
6 * Jose Renau <renau@acm.org>
7 * Philip Blundell <philb@gnu.org>
8 * Andrea Arcangeli
9 *
10 * based on work by Grant Guenther <grant@torque.net>
11 * and Philip Blundell
12 *
13 * Any part of this program may be used in documents licensed under
14 * the GNU Free Documentation License, Version 1.1 or any later version
15 * published by the Free Software Foundation.
16 */
17
18#undef PARPORT_DEBUG_SHARING /* undef for production */
19
20#include <linux/config.h>
21#include <linux/module.h>
22#include <linux/string.h>
23#include <linux/threads.h>
24#include <linux/parport.h>
25#include <linux/delay.h>
26#include <linux/errno.h>
27#include <linux/interrupt.h>
28#include <linux/ioport.h>
29#include <linux/kernel.h>
30#include <linux/slab.h>
31#include <linux/sched.h>
32#include <linux/kmod.h>
33
34#include <linux/spinlock.h>
35#include <asm/irq.h>
36
37#undef PARPORT_PARANOID
38
39#define PARPORT_DEFAULT_TIMESLICE (HZ/5)
40
41unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE;
42int parport_default_spintime = DEFAULT_SPIN_TIME;
43
44static LIST_HEAD(portlist);
45static DEFINE_SPINLOCK(parportlist_lock);
46
47/* list of all allocated ports, sorted by ->number */
48static LIST_HEAD(all_ports);
49static DEFINE_SPINLOCK(full_list_lock);
50
51static LIST_HEAD(drivers);
52
53static DECLARE_MUTEX(registration_lock);
54
55/* What you can do to a port that's gone away.. */
56static void dead_write_lines (struct parport *p, unsigned char b){}
57static unsigned char dead_read_lines (struct parport *p) { return 0; }
58static unsigned char dead_frob_lines (struct parport *p, unsigned char b,
59 unsigned char c) { return 0; }
60static void dead_onearg (struct parport *p){}
61static void dead_initstate (struct pardevice *d, struct parport_state *s) { }
62static void dead_state (struct parport *p, struct parport_state *s) { }
63static size_t dead_write (struct parport *p, const void *b, size_t l, int f)
64{ return 0; }
65static size_t dead_read (struct parport *p, void *b, size_t l, int f)
66{ return 0; }
67static struct parport_operations dead_ops = {
68 .write_data = dead_write_lines, /* data */
69 .read_data = dead_read_lines,
70
71 .write_control = dead_write_lines, /* control */
72 .read_control = dead_read_lines,
73 .frob_control = dead_frob_lines,
74
75 .read_status = dead_read_lines, /* status */
76
77 .enable_irq = dead_onearg, /* enable_irq */
78 .disable_irq = dead_onearg, /* disable_irq */
79
80 .data_forward = dead_onearg, /* data_forward */
81 .data_reverse = dead_onearg, /* data_reverse */
82
83 .init_state = dead_initstate, /* init_state */
84 .save_state = dead_state,
85 .restore_state = dead_state,
86
87 .epp_write_data = dead_write, /* epp */
88 .epp_read_data = dead_read,
89 .epp_write_addr = dead_write,
90 .epp_read_addr = dead_read,
91
92 .ecp_write_data = dead_write, /* ecp */
93 .ecp_read_data = dead_read,
94 .ecp_write_addr = dead_write,
95
96 .compat_write_data = dead_write, /* compat */
97 .nibble_read_data = dead_read, /* nibble */
98 .byte_read_data = dead_read, /* byte */
99
100 .owner = NULL,
101};
102
103/* Call attach(port) for each registered driver. */
104static void attach_driver_chain(struct parport *port)
105{
106 /* caller has exclusive registration_lock */
107 struct parport_driver *drv;
108 list_for_each_entry(drv, &drivers, list)
109 drv->attach(port);
110}
111
112/* Call detach(port) for each registered driver. */
113static void detach_driver_chain(struct parport *port)
114{
115 struct parport_driver *drv;
116 /* caller has exclusive registration_lock */
117 list_for_each_entry(drv, &drivers, list)
118 drv->detach (port);
119}
120
121/* Ask kmod for some lowlevel drivers. */
122static void get_lowlevel_driver (void)
123{
124 /* There is no actual module called this: you should set
125 * up an alias for modutils. */
126 request_module ("parport_lowlevel");
127}
128
129/**
130 * parport_register_driver - register a parallel port device driver
131 * @drv: structure describing the driver
132 *
133 * This can be called by a parallel port device driver in order
134 * to receive notifications about ports being found in the
135 * system, as well as ports no longer available.
136 *
137 * The @drv structure is allocated by the caller and must not be
138 * deallocated until after calling parport_unregister_driver().
139 *
140 * The driver's attach() function may block. The port that
141 * attach() is given will be valid for the duration of the
142 * callback, but if the driver wants to take a copy of the
143 * pointer it must call parport_get_port() to do so. Calling
144 * parport_register_device() on that port will do this for you.
145 *
146 * The driver's detach() function may block. The port that
147 * detach() is given will be valid for the duration of the
148 * callback, but if the driver wants to take a copy of the
149 * pointer it must call parport_get_port() to do so.
150 *
151 * Returns 0 on success. Currently it always succeeds.
152 **/
153
154int parport_register_driver (struct parport_driver *drv)
155{
156 struct parport *port;
157
158 if (list_empty(&portlist))
159 get_lowlevel_driver ();
160
161 down(&registration_lock);
162 list_for_each_entry(port, &portlist, list)
163 drv->attach(port);
164 list_add(&drv->list, &drivers);
165 up(&registration_lock);
166
167 return 0;
168}
169
170/**
171 * parport_unregister_driver - deregister a parallel port device driver
172 * @drv: structure describing the driver that was given to
173 * parport_register_driver()
174 *
175 * This should be called by a parallel port device driver that
176 * has registered itself using parport_register_driver() when it
177 * is about to be unloaded.
178 *
179 * When it returns, the driver's attach() routine will no longer
180 * be called, and for each port that attach() was called for, the
181 * detach() routine will have been called.
182 *
183 * All the driver's attach() and detach() calls are guaranteed to have
184 * finished by the time this function returns.
185 **/
186
187void parport_unregister_driver (struct parport_driver *drv)
188{
189 struct parport *port;
190
191 down(&registration_lock);
192 list_del_init(&drv->list);
193 list_for_each_entry(port, &portlist, list)
194 drv->detach(port);
195 up(&registration_lock);
196}
197
198static void free_port (struct parport *port)
199{
200 int d;
201 spin_lock(&full_list_lock);
202 list_del(&port->full_list);
203 spin_unlock(&full_list_lock);
204 for (d = 0; d < 5; d++) {
Jesper Juhl6044ec82005-11-07 01:01:32 -0800205 kfree(port->probe_info[d].class_name);
206 kfree(port->probe_info[d].mfr);
207 kfree(port->probe_info[d].model);
208 kfree(port->probe_info[d].cmdset);
209 kfree(port->probe_info[d].description);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 }
211
212 kfree(port->name);
213 kfree(port);
214}
215
216/**
217 * parport_get_port - increment a port's reference count
218 * @port: the port
219 *
220 * This ensure's that a struct parport pointer remains valid
221 * until the matching parport_put_port() call.
222 **/
223
224struct parport *parport_get_port (struct parport *port)
225{
226 atomic_inc (&port->ref_count);
227 return port;
228}
229
230/**
231 * parport_put_port - decrement a port's reference count
232 * @port: the port
233 *
234 * This should be called once for each call to parport_get_port(),
235 * once the port is no longer needed.
236 **/
237
238void parport_put_port (struct parport *port)
239{
240 if (atomic_dec_and_test (&port->ref_count))
241 /* Can destroy it now. */
242 free_port (port);
243
244 return;
245}
246
247/**
248 * parport_register_port - register a parallel port
249 * @base: base I/O address
250 * @irq: IRQ line
251 * @dma: DMA channel
252 * @ops: pointer to the port driver's port operations structure
253 *
254 * When a parallel port (lowlevel) driver finds a port that
255 * should be made available to parallel port device drivers, it
256 * should call parport_register_port(). The @base, @irq, and
257 * @dma parameters are for the convenience of port drivers, and
258 * for ports where they aren't meaningful needn't be set to
259 * anything special. They can be altered afterwards by adjusting
260 * the relevant members of the parport structure that is returned
261 * and represents the port. They should not be tampered with
262 * after calling parport_announce_port, however.
263 *
264 * If there are parallel port device drivers in the system that
265 * have registered themselves using parport_register_driver(),
266 * they are not told about the port at this time; that is done by
267 * parport_announce_port().
268 *
269 * The @ops structure is allocated by the caller, and must not be
270 * deallocated before calling parport_remove_port().
271 *
272 * If there is no memory to allocate a new parport structure,
273 * this function will return %NULL.
274 **/
275
276struct parport *parport_register_port(unsigned long base, int irq, int dma,
277 struct parport_operations *ops)
278{
279 struct list_head *l;
280 struct parport *tmp;
281 int num;
282 int device;
283 char *name;
284
285 tmp = kmalloc(sizeof(struct parport), GFP_KERNEL);
286 if (!tmp) {
287 printk(KERN_WARNING "parport: memory squeeze\n");
288 return NULL;
289 }
290
291 /* Init our structure */
292 memset(tmp, 0, sizeof(struct parport));
293 tmp->base = base;
294 tmp->irq = irq;
295 tmp->dma = dma;
296 tmp->muxport = tmp->daisy = tmp->muxsel = -1;
297 tmp->modes = 0;
298 INIT_LIST_HEAD(&tmp->list);
299 tmp->devices = tmp->cad = NULL;
300 tmp->flags = 0;
301 tmp->ops = ops;
302 tmp->physport = tmp;
303 memset (tmp->probe_info, 0, 5 * sizeof (struct parport_device_info));
304 rwlock_init(&tmp->cad_lock);
305 spin_lock_init(&tmp->waitlist_lock);
306 spin_lock_init(&tmp->pardevice_lock);
307 tmp->ieee1284.mode = IEEE1284_MODE_COMPAT;
308 tmp->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
309 init_MUTEX_LOCKED (&tmp->ieee1284.irq); /* actually a semaphore at 0 */
310 tmp->spintime = parport_default_spintime;
311 atomic_set (&tmp->ref_count, 1);
312 INIT_LIST_HEAD(&tmp->full_list);
313
314 name = kmalloc(15, GFP_KERNEL);
315 if (!name) {
316 printk(KERN_ERR "parport: memory squeeze\n");
317 kfree(tmp);
318 return NULL;
319 }
320 /* Search for the lowest free parport number. */
321
322 spin_lock(&full_list_lock);
323 for (l = all_ports.next, num = 0; l != &all_ports; l = l->next, num++) {
324 struct parport *p = list_entry(l, struct parport, full_list);
325 if (p->number != num)
326 break;
327 }
328 tmp->portnum = tmp->number = num;
329 list_add_tail(&tmp->full_list, l);
330 spin_unlock(&full_list_lock);
331
332 /*
333 * Now that the portnum is known finish doing the Init.
334 */
335 sprintf(name, "parport%d", tmp->portnum = tmp->number);
336 tmp->name = name;
337
338 for (device = 0; device < 5; device++)
339 /* assume the worst */
340 tmp->probe_info[device].class = PARPORT_CLASS_LEGACY;
341
342 tmp->waithead = tmp->waittail = NULL;
343
344 return tmp;
345}
346
347/**
348 * parport_announce_port - tell device drivers about a parallel port
349 * @port: parallel port to announce
350 *
351 * After a port driver has registered a parallel port with
352 * parport_register_port, and performed any necessary
353 * initialisation or adjustments, it should call
354 * parport_announce_port() in order to notify all device drivers
355 * that have called parport_register_driver(). Their attach()
356 * functions will be called, with @port as the parameter.
357 **/
358
359void parport_announce_port (struct parport *port)
360{
361 int i;
362
363#ifdef CONFIG_PARPORT_1284
364 /* Analyse the IEEE1284.3 topology of the port. */
365 parport_daisy_init(port);
366#endif
367
368 parport_proc_register(port);
369 down(&registration_lock);
370 spin_lock_irq(&parportlist_lock);
371 list_add_tail(&port->list, &portlist);
372 for (i = 1; i < 3; i++) {
373 struct parport *slave = port->slaves[i-1];
374 if (slave)
375 list_add_tail(&slave->list, &portlist);
376 }
377 spin_unlock_irq(&parportlist_lock);
378
379 /* Let drivers know that new port(s) has arrived. */
380 attach_driver_chain (port);
381 for (i = 1; i < 3; i++) {
382 struct parport *slave = port->slaves[i-1];
383 if (slave)
384 attach_driver_chain(slave);
385 }
386 up(&registration_lock);
387}
388
389/**
390 * parport_remove_port - deregister a parallel port
391 * @port: parallel port to deregister
392 *
393 * When a parallel port driver is forcibly unloaded, or a
394 * parallel port becomes inaccessible, the port driver must call
395 * this function in order to deal with device drivers that still
396 * want to use it.
397 *
398 * The parport structure associated with the port has its
399 * operations structure replaced with one containing 'null'
400 * operations that return errors or just don't do anything.
401 *
402 * Any drivers that have registered themselves using
403 * parport_register_driver() are notified that the port is no
404 * longer accessible by having their detach() routines called
405 * with @port as the parameter.
406 **/
407
408void parport_remove_port(struct parport *port)
409{
410 int i;
411
412 down(&registration_lock);
413
414 /* Spread the word. */
415 detach_driver_chain (port);
416
417#ifdef CONFIG_PARPORT_1284
418 /* Forget the IEEE1284.3 topology of the port. */
419 parport_daisy_fini(port);
420 for (i = 1; i < 3; i++) {
421 struct parport *slave = port->slaves[i-1];
422 if (!slave)
423 continue;
424 detach_driver_chain(slave);
425 parport_daisy_fini(slave);
426 }
427#endif
428
429 port->ops = &dead_ops;
430 spin_lock(&parportlist_lock);
431 list_del_init(&port->list);
432 for (i = 1; i < 3; i++) {
433 struct parport *slave = port->slaves[i-1];
434 if (slave)
435 list_del_init(&slave->list);
436 }
437 spin_unlock(&parportlist_lock);
438
439 up(&registration_lock);
440
441 parport_proc_unregister(port);
442
443 for (i = 1; i < 3; i++) {
444 struct parport *slave = port->slaves[i-1];
445 if (slave)
446 parport_put_port(slave);
447 }
448}
449
450/**
451 * parport_register_device - register a device on a parallel port
452 * @port: port to which the device is attached
453 * @name: a name to refer to the device
454 * @pf: preemption callback
455 * @kf: kick callback (wake-up)
456 * @irq_func: interrupt handler
457 * @flags: registration flags
458 * @handle: data for callback functions
459 *
460 * This function, called by parallel port device drivers,
461 * declares that a device is connected to a port, and tells the
462 * system all it needs to know.
463 *
464 * The @name is allocated by the caller and must not be
465 * deallocated until the caller calls @parport_unregister_device
466 * for that device.
467 *
468 * The preemption callback function, @pf, is called when this
469 * device driver has claimed access to the port but another
470 * device driver wants to use it. It is given @handle as its
471 * parameter, and should return zero if it is willing for the
472 * system to release the port to another driver on its behalf.
473 * If it wants to keep control of the port it should return
474 * non-zero, and no action will be taken. It is good manners for
475 * the driver to try to release the port at the earliest
476 * opportunity after its preemption callback rejects a preemption
477 * attempt. Note that if a preemption callback is happy for
478 * preemption to go ahead, there is no need to release the port;
479 * it is done automatically. This function may not block, as it
480 * may be called from interrupt context. If the device driver
481 * does not support preemption, @pf can be %NULL.
482 *
483 * The wake-up ("kick") callback function, @kf, is called when
484 * the port is available to be claimed for exclusive access; that
485 * is, parport_claim() is guaranteed to succeed when called from
486 * inside the wake-up callback function. If the driver wants to
487 * claim the port it should do so; otherwise, it need not take
488 * any action. This function may not block, as it may be called
489 * from interrupt context. If the device driver does not want to
490 * be explicitly invited to claim the port in this way, @kf can
491 * be %NULL.
492 *
493 * The interrupt handler, @irq_func, is called when an interrupt
494 * arrives from the parallel port. Note that if a device driver
495 * wants to use interrupts it should use parport_enable_irq(),
496 * and can also check the irq member of the parport structure
497 * representing the port.
498 *
499 * The parallel port (lowlevel) driver is the one that has called
500 * request_irq() and whose interrupt handler is called first.
501 * This handler does whatever needs to be done to the hardware to
502 * acknowledge the interrupt (for PC-style ports there is nothing
503 * special to be done). It then tells the IEEE 1284 code about
504 * the interrupt, which may involve reacting to an IEEE 1284
505 * event depending on the current IEEE 1284 phase. After this,
506 * it calls @irq_func. Needless to say, @irq_func will be called
507 * from interrupt context, and may not block.
508 *
509 * The %PARPORT_DEV_EXCL flag is for preventing port sharing, and
510 * so should only be used when sharing the port with other device
511 * drivers is impossible and would lead to incorrect behaviour.
512 * Use it sparingly! Normally, @flags will be zero.
513 *
514 * This function returns a pointer to a structure that represents
515 * the device on the port, or %NULL if there is not enough memory
516 * to allocate space for that structure.
517 **/
518
519struct pardevice *
520parport_register_device(struct parport *port, const char *name,
521 int (*pf)(void *), void (*kf)(void *),
522 void (*irq_func)(int, void *, struct pt_regs *),
523 int flags, void *handle)
524{
525 struct pardevice *tmp;
526
527 if (port->physport->flags & PARPORT_FLAG_EXCL) {
528 /* An exclusive device is registered. */
529 printk (KERN_DEBUG "%s: no more devices allowed\n",
530 port->name);
531 return NULL;
532 }
533
534 if (flags & PARPORT_DEV_LURK) {
535 if (!pf || !kf) {
536 printk(KERN_INFO "%s: refused to register lurking device (%s) without callbacks\n", port->name, name);
537 return NULL;
538 }
539 }
540
541 /* We up our own module reference count, and that of the port
542 on which a device is to be registered, to ensure that
543 neither of us gets unloaded while we sleep in (e.g.)
544 kmalloc.
545 */
546 if (!try_module_get(port->ops->owner)) {
547 return NULL;
548 }
549
550 parport_get_port (port);
551
552 tmp = kmalloc(sizeof(struct pardevice), GFP_KERNEL);
553 if (tmp == NULL) {
554 printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name);
555 goto out;
556 }
557
558 tmp->state = kmalloc(sizeof(struct parport_state), GFP_KERNEL);
559 if (tmp->state == NULL) {
560 printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name);
561 goto out_free_pardevice;
562 }
563
564 tmp->name = name;
565 tmp->port = port;
566 tmp->daisy = -1;
567 tmp->preempt = pf;
568 tmp->wakeup = kf;
569 tmp->private = handle;
570 tmp->flags = flags;
571 tmp->irq_func = irq_func;
572 tmp->waiting = 0;
573 tmp->timeout = 5 * HZ;
574
575 /* Chain this onto the list */
576 tmp->prev = NULL;
577 /*
578 * This function must not run from an irq handler so we don' t need
579 * to clear irq on the local CPU. -arca
580 */
581 spin_lock(&port->physport->pardevice_lock);
582
583 if (flags & PARPORT_DEV_EXCL) {
584 if (port->physport->devices) {
585 spin_unlock (&port->physport->pardevice_lock);
586 printk (KERN_DEBUG
587 "%s: cannot grant exclusive access for "
588 "device %s\n", port->name, name);
589 goto out_free_all;
590 }
591 port->flags |= PARPORT_FLAG_EXCL;
592 }
593
594 tmp->next = port->physport->devices;
595 wmb(); /* Make sure that tmp->next is written before it's
596 added to the list; see comments marked 'no locking
597 required' */
598 if (port->physport->devices)
599 port->physport->devices->prev = tmp;
600 port->physport->devices = tmp;
601 spin_unlock(&port->physport->pardevice_lock);
602
603 init_waitqueue_head(&tmp->wait_q);
604 tmp->timeslice = parport_default_timeslice;
605 tmp->waitnext = tmp->waitprev = NULL;
606
607 /*
608 * This has to be run as last thing since init_state may need other
609 * pardevice fields. -arca
610 */
611 port->ops->init_state(tmp, tmp->state);
612 parport_device_proc_register(tmp);
613 return tmp;
614
615 out_free_all:
Jesper Juhl6044ec82005-11-07 01:01:32 -0800616 kfree(tmp->state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 out_free_pardevice:
Jesper Juhl6044ec82005-11-07 01:01:32 -0800618 kfree(tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 out:
620 parport_put_port (port);
621 module_put(port->ops->owner);
622
623 return NULL;
624}
625
626/**
627 * parport_unregister_device - deregister a device on a parallel port
628 * @dev: pointer to structure representing device
629 *
630 * This undoes the effect of parport_register_device().
631 **/
632
633void parport_unregister_device(struct pardevice *dev)
634{
635 struct parport *port;
636
637#ifdef PARPORT_PARANOID
638 if (dev == NULL) {
639 printk(KERN_ERR "parport_unregister_device: passed NULL\n");
640 return;
641 }
642#endif
643
644 parport_device_proc_unregister(dev);
645
646 port = dev->port->physport;
647
648 if (port->cad == dev) {
649 printk(KERN_DEBUG "%s: %s forgot to release port\n",
650 port->name, dev->name);
651 parport_release (dev);
652 }
653
654 spin_lock(&port->pardevice_lock);
655 if (dev->next)
656 dev->next->prev = dev->prev;
657 if (dev->prev)
658 dev->prev->next = dev->next;
659 else
660 port->devices = dev->next;
661
662 if (dev->flags & PARPORT_DEV_EXCL)
663 port->flags &= ~PARPORT_FLAG_EXCL;
664
665 spin_unlock(&port->pardevice_lock);
666
667 /* Make sure we haven't left any pointers around in the wait
668 * list. */
669 spin_lock (&port->waitlist_lock);
670 if (dev->waitprev || dev->waitnext || port->waithead == dev) {
671 if (dev->waitprev)
672 dev->waitprev->waitnext = dev->waitnext;
673 else
674 port->waithead = dev->waitnext;
675 if (dev->waitnext)
676 dev->waitnext->waitprev = dev->waitprev;
677 else
678 port->waittail = dev->waitprev;
679 }
680 spin_unlock (&port->waitlist_lock);
681
682 kfree(dev->state);
683 kfree(dev);
684
685 module_put(port->ops->owner);
686 parport_put_port (port);
687}
688
689/**
690 * parport_find_number - find a parallel port by number
691 * @number: parallel port number
692 *
693 * This returns the parallel port with the specified number, or
694 * %NULL if there is none.
695 *
696 * There is an implicit parport_get_port() done already; to throw
697 * away the reference to the port that parport_find_number()
698 * gives you, use parport_put_port().
699 */
700
701struct parport *parport_find_number (int number)
702{
703 struct parport *port, *result = NULL;
704
705 if (list_empty(&portlist))
706 get_lowlevel_driver ();
707
708 spin_lock (&parportlist_lock);
709 list_for_each_entry(port, &portlist, list) {
710 if (port->number == number) {
711 result = parport_get_port (port);
712 break;
713 }
714 }
715 spin_unlock (&parportlist_lock);
716 return result;
717}
718
719/**
720 * parport_find_base - find a parallel port by base address
721 * @base: base I/O address
722 *
723 * This returns the parallel port with the specified base
724 * address, or %NULL if there is none.
725 *
726 * There is an implicit parport_get_port() done already; to throw
727 * away the reference to the port that parport_find_base()
728 * gives you, use parport_put_port().
729 */
730
731struct parport *parport_find_base (unsigned long base)
732{
733 struct parport *port, *result = NULL;
734
735 if (list_empty(&portlist))
736 get_lowlevel_driver ();
737
738 spin_lock (&parportlist_lock);
739 list_for_each_entry(port, &portlist, list) {
740 if (port->base == base) {
741 result = parport_get_port (port);
742 break;
743 }
744 }
745 spin_unlock (&parportlist_lock);
746 return result;
747}
748
749/**
750 * parport_claim - claim access to a parallel port device
751 * @dev: pointer to structure representing a device on the port
752 *
753 * This function will not block and so can be used from interrupt
754 * context. If parport_claim() succeeds in claiming access to
755 * the port it returns zero and the port is available to use. It
756 * may fail (returning non-zero) if the port is in use by another
757 * driver and that driver is not willing to relinquish control of
758 * the port.
759 **/
760
761int parport_claim(struct pardevice *dev)
762{
763 struct pardevice *oldcad;
764 struct parport *port = dev->port->physport;
765 unsigned long flags;
766
767 if (port->cad == dev) {
768 printk(KERN_INFO "%s: %s already owner\n",
769 dev->port->name,dev->name);
770 return 0;
771 }
772
773 /* Preempt any current device */
774 write_lock_irqsave (&port->cad_lock, flags);
775 if ((oldcad = port->cad) != NULL) {
776 if (oldcad->preempt) {
777 if (oldcad->preempt(oldcad->private))
778 goto blocked;
779 port->ops->save_state(port, dev->state);
780 } else
781 goto blocked;
782
783 if (port->cad != oldcad) {
784 /* I think we'll actually deadlock rather than
785 get here, but just in case.. */
786 printk(KERN_WARNING
787 "%s: %s released port when preempted!\n",
788 port->name, oldcad->name);
789 if (port->cad)
790 goto blocked;
791 }
792 }
793
794 /* Can't fail from now on, so mark ourselves as no longer waiting. */
795 if (dev->waiting & 1) {
796 dev->waiting = 0;
797
798 /* Take ourselves out of the wait list again. */
799 spin_lock_irq (&port->waitlist_lock);
800 if (dev->waitprev)
801 dev->waitprev->waitnext = dev->waitnext;
802 else
803 port->waithead = dev->waitnext;
804 if (dev->waitnext)
805 dev->waitnext->waitprev = dev->waitprev;
806 else
807 port->waittail = dev->waitprev;
808 spin_unlock_irq (&port->waitlist_lock);
809 dev->waitprev = dev->waitnext = NULL;
810 }
811
812 /* Now we do the change of devices */
813 port->cad = dev;
814
815#ifdef CONFIG_PARPORT_1284
816 /* If it's a mux port, select it. */
817 if (dev->port->muxport >= 0) {
818 /* FIXME */
819 port->muxsel = dev->port->muxport;
820 }
821
822 /* If it's a daisy chain device, select it. */
823 if (dev->daisy >= 0) {
824 /* This could be lazier. */
825 if (!parport_daisy_select (port, dev->daisy,
826 IEEE1284_MODE_COMPAT))
827 port->daisy = dev->daisy;
828 }
829#endif /* IEEE1284.3 support */
830
831 /* Restore control registers */
832 port->ops->restore_state(port, dev->state);
833 write_unlock_irqrestore(&port->cad_lock, flags);
834 dev->time = jiffies;
835 return 0;
836
837blocked:
838 /* If this is the first time we tried to claim the port, register an
839 interest. This is only allowed for devices sleeping in
840 parport_claim_or_block(), or those with a wakeup function. */
841
842 /* The cad_lock is still held for writing here */
843 if (dev->waiting & 2 || dev->wakeup) {
844 spin_lock (&port->waitlist_lock);
845 if (test_and_set_bit(0, &dev->waiting) == 0) {
846 /* First add ourselves to the end of the wait list. */
847 dev->waitnext = NULL;
848 dev->waitprev = port->waittail;
849 if (port->waittail) {
850 port->waittail->waitnext = dev;
851 port->waittail = dev;
852 } else
853 port->waithead = port->waittail = dev;
854 }
855 spin_unlock (&port->waitlist_lock);
856 }
857 write_unlock_irqrestore (&port->cad_lock, flags);
858 return -EAGAIN;
859}
860
861/**
862 * parport_claim_or_block - claim access to a parallel port device
863 * @dev: pointer to structure representing a device on the port
864 *
865 * This behaves like parport_claim(), but will block if necessary
866 * to wait for the port to be free. A return value of 1
867 * indicates that it slept; 0 means that it succeeded without
868 * needing to sleep. A negative error code indicates failure.
869 **/
870
871int parport_claim_or_block(struct pardevice *dev)
872{
873 int r;
874
875 /* Signal to parport_claim() that we can wait even without a
876 wakeup function. */
877 dev->waiting = 2;
878
879 /* Try to claim the port. If this fails, we need to sleep. */
880 r = parport_claim(dev);
881 if (r == -EAGAIN) {
882#ifdef PARPORT_DEBUG_SHARING
883 printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n", dev->name);
884#endif
885 /*
886 * FIXME!!! Use the proper locking for dev->waiting,
887 * and make this use the "wait_event_interruptible()"
888 * interfaces. The cli/sti that used to be here
889 * did nothing.
890 *
891 * See also parport_release()
892 */
893
894 /* If dev->waiting is clear now, an interrupt
895 gave us the port and we would deadlock if we slept. */
896 if (dev->waiting) {
897 interruptible_sleep_on (&dev->wait_q);
898 if (signal_pending (current)) {
899 return -EINTR;
900 }
901 r = 1;
902 } else {
903 r = 0;
904#ifdef PARPORT_DEBUG_SHARING
905 printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
906 dev->name);
907#endif
908 }
909
910#ifdef PARPORT_DEBUG_SHARING
911 if (dev->port->physport->cad != dev)
912 printk(KERN_DEBUG "%s: exiting parport_claim_or_block "
913 "but %s owns port!\n", dev->name,
914 dev->port->physport->cad ?
915 dev->port->physport->cad->name:"nobody");
916#endif
917 }
918 dev->waiting = 0;
919 return r;
920}
921
922/**
923 * parport_release - give up access to a parallel port device
924 * @dev: pointer to structure representing parallel port device
925 *
926 * This function cannot fail, but it should not be called without
927 * the port claimed. Similarly, if the port is already claimed
928 * you should not try claiming it again.
929 **/
930
931void parport_release(struct pardevice *dev)
932{
933 struct parport *port = dev->port->physport;
934 struct pardevice *pd;
935 unsigned long flags;
936
937 /* Make sure that dev is the current device */
938 write_lock_irqsave(&port->cad_lock, flags);
939 if (port->cad != dev) {
940 write_unlock_irqrestore (&port->cad_lock, flags);
941 printk(KERN_WARNING "%s: %s tried to release parport "
942 "when not owner\n", port->name, dev->name);
943 return;
944 }
945
946#ifdef CONFIG_PARPORT_1284
947 /* If this is on a mux port, deselect it. */
948 if (dev->port->muxport >= 0) {
949 /* FIXME */
950 port->muxsel = -1;
951 }
952
953 /* If this is a daisy device, deselect it. */
954 if (dev->daisy >= 0) {
955 parport_daisy_deselect_all (port);
956 port->daisy = -1;
957 }
958#endif
959
960 port->cad = NULL;
961 write_unlock_irqrestore(&port->cad_lock, flags);
962
963 /* Save control registers */
964 port->ops->save_state(port, dev->state);
965
966 /* If anybody is waiting, find out who's been there longest and
967 then wake them up. (Note: no locking required) */
968 /* !!! LOCKING IS NEEDED HERE */
969 for (pd = port->waithead; pd; pd = pd->waitnext) {
970 if (pd->waiting & 2) { /* sleeping in claim_or_block */
971 parport_claim(pd);
972 if (waitqueue_active(&pd->wait_q))
973 wake_up_interruptible(&pd->wait_q);
974 return;
975 } else if (pd->wakeup) {
976 pd->wakeup(pd->private);
977 if (dev->port->cad) /* racy but no matter */
978 return;
979 } else {
980 printk(KERN_ERR "%s: don't know how to wake %s\n", port->name, pd->name);
981 }
982 }
983
984 /* Nobody was waiting, so walk the list to see if anyone is
985 interested in being woken up. (Note: no locking required) */
986 /* !!! LOCKING IS NEEDED HERE */
987 for (pd = port->devices; (port->cad == NULL) && pd; pd = pd->next) {
988 if (pd->wakeup && pd != dev)
989 pd->wakeup(pd->private);
990 }
991}
992
993/* Exported symbols for modules. */
994
995EXPORT_SYMBOL(parport_claim);
996EXPORT_SYMBOL(parport_claim_or_block);
997EXPORT_SYMBOL(parport_release);
998EXPORT_SYMBOL(parport_register_port);
999EXPORT_SYMBOL(parport_announce_port);
1000EXPORT_SYMBOL(parport_remove_port);
1001EXPORT_SYMBOL(parport_register_driver);
1002EXPORT_SYMBOL(parport_unregister_driver);
1003EXPORT_SYMBOL(parport_register_device);
1004EXPORT_SYMBOL(parport_unregister_device);
Marko Kohtala94b82092006-01-06 00:19:51 -08001005EXPORT_SYMBOL(parport_get_port);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006EXPORT_SYMBOL(parport_put_port);
1007EXPORT_SYMBOL(parport_find_number);
1008EXPORT_SYMBOL(parport_find_base);
1009
1010MODULE_LICENSE("GPL");