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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
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/module.h>
21#include <linux/string.h>
22#include <linux/threads.h>
23#include <linux/parport.h>
24#include <linux/delay.h>
25#include <linux/errno.h>
26#include <linux/interrupt.h>
27#include <linux/ioport.h>
28#include <linux/kernel.h>
29#include <linux/slab.h>
30#include <linux/sched.h>
31#include <linux/kmod.h>
32
33#include <linux/spinlock.h>
Ingo Molnar14cc3e22006-03-26 01:37:14 -080034#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#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
Ingo Molnar14cc3e22006-03-26 01:37:14 -080053static DEFINE_MUTEX(registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
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
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800161 mutex_lock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 list_for_each_entry(port, &portlist, list)
163 drv->attach(port);
164 list_add(&drv->list, &drivers);
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800165 mutex_unlock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
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
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800191 mutex_lock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 list_del_init(&drv->list);
193 list_for_each_entry(port, &portlist, list)
194 drv->detach(port);
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800195 mutex_unlock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196}
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 *
Randy Dunlap7d469722006-06-25 05:49:29 -0700220 * This ensures that a struct parport pointer remains valid
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 * 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
David Brownellc15a3832007-05-08 00:27:35 -0700368 if (!port->dev)
369 printk(KERN_WARNING "%s: fix this legacy "
370 "no-device port driver!\n",
371 port->name);
372
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 parport_proc_register(port);
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800374 mutex_lock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 spin_lock_irq(&parportlist_lock);
376 list_add_tail(&port->list, &portlist);
377 for (i = 1; i < 3; i++) {
378 struct parport *slave = port->slaves[i-1];
379 if (slave)
380 list_add_tail(&slave->list, &portlist);
381 }
382 spin_unlock_irq(&parportlist_lock);
383
384 /* Let drivers know that new port(s) has arrived. */
385 attach_driver_chain (port);
386 for (i = 1; i < 3; i++) {
387 struct parport *slave = port->slaves[i-1];
388 if (slave)
389 attach_driver_chain(slave);
390 }
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800391 mutex_unlock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392}
393
394/**
395 * parport_remove_port - deregister a parallel port
396 * @port: parallel port to deregister
397 *
398 * When a parallel port driver is forcibly unloaded, or a
399 * parallel port becomes inaccessible, the port driver must call
400 * this function in order to deal with device drivers that still
401 * want to use it.
402 *
403 * The parport structure associated with the port has its
404 * operations structure replaced with one containing 'null'
405 * operations that return errors or just don't do anything.
406 *
407 * Any drivers that have registered themselves using
408 * parport_register_driver() are notified that the port is no
409 * longer accessible by having their detach() routines called
410 * with @port as the parameter.
411 **/
412
413void parport_remove_port(struct parport *port)
414{
415 int i;
416
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800417 mutex_lock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
419 /* Spread the word. */
420 detach_driver_chain (port);
421
422#ifdef CONFIG_PARPORT_1284
423 /* Forget the IEEE1284.3 topology of the port. */
424 parport_daisy_fini(port);
425 for (i = 1; i < 3; i++) {
426 struct parport *slave = port->slaves[i-1];
427 if (!slave)
428 continue;
429 detach_driver_chain(slave);
430 parport_daisy_fini(slave);
431 }
432#endif
433
434 port->ops = &dead_ops;
435 spin_lock(&parportlist_lock);
436 list_del_init(&port->list);
437 for (i = 1; i < 3; i++) {
438 struct parport *slave = port->slaves[i-1];
439 if (slave)
440 list_del_init(&slave->list);
441 }
442 spin_unlock(&parportlist_lock);
443
Ingo Molnar14cc3e22006-03-26 01:37:14 -0800444 mutex_unlock(&registration_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445
446 parport_proc_unregister(port);
447
448 for (i = 1; i < 3; i++) {
449 struct parport *slave = port->slaves[i-1];
450 if (slave)
451 parport_put_port(slave);
452 }
453}
454
455/**
456 * parport_register_device - register a device on a parallel port
457 * @port: port to which the device is attached
458 * @name: a name to refer to the device
459 * @pf: preemption callback
460 * @kf: kick callback (wake-up)
461 * @irq_func: interrupt handler
462 * @flags: registration flags
463 * @handle: data for callback functions
464 *
465 * This function, called by parallel port device drivers,
466 * declares that a device is connected to a port, and tells the
467 * system all it needs to know.
468 *
469 * The @name is allocated by the caller and must not be
470 * deallocated until the caller calls @parport_unregister_device
471 * for that device.
472 *
473 * The preemption callback function, @pf, is called when this
474 * device driver has claimed access to the port but another
475 * device driver wants to use it. It is given @handle as its
476 * parameter, and should return zero if it is willing for the
477 * system to release the port to another driver on its behalf.
478 * If it wants to keep control of the port it should return
479 * non-zero, and no action will be taken. It is good manners for
480 * the driver to try to release the port at the earliest
481 * opportunity after its preemption callback rejects a preemption
482 * attempt. Note that if a preemption callback is happy for
483 * preemption to go ahead, there is no need to release the port;
484 * it is done automatically. This function may not block, as it
485 * may be called from interrupt context. If the device driver
486 * does not support preemption, @pf can be %NULL.
487 *
488 * The wake-up ("kick") callback function, @kf, is called when
489 * the port is available to be claimed for exclusive access; that
490 * is, parport_claim() is guaranteed to succeed when called from
491 * inside the wake-up callback function. If the driver wants to
492 * claim the port it should do so; otherwise, it need not take
493 * any action. This function may not block, as it may be called
494 * from interrupt context. If the device driver does not want to
495 * be explicitly invited to claim the port in this way, @kf can
496 * be %NULL.
497 *
498 * The interrupt handler, @irq_func, is called when an interrupt
499 * arrives from the parallel port. Note that if a device driver
500 * wants to use interrupts it should use parport_enable_irq(),
501 * and can also check the irq member of the parport structure
502 * representing the port.
503 *
504 * The parallel port (lowlevel) driver is the one that has called
505 * request_irq() and whose interrupt handler is called first.
506 * This handler does whatever needs to be done to the hardware to
507 * acknowledge the interrupt (for PC-style ports there is nothing
508 * special to be done). It then tells the IEEE 1284 code about
509 * the interrupt, which may involve reacting to an IEEE 1284
510 * event depending on the current IEEE 1284 phase. After this,
511 * it calls @irq_func. Needless to say, @irq_func will be called
512 * from interrupt context, and may not block.
513 *
514 * The %PARPORT_DEV_EXCL flag is for preventing port sharing, and
515 * so should only be used when sharing the port with other device
516 * drivers is impossible and would lead to incorrect behaviour.
517 * Use it sparingly! Normally, @flags will be zero.
518 *
519 * This function returns a pointer to a structure that represents
520 * the device on the port, or %NULL if there is not enough memory
521 * to allocate space for that structure.
522 **/
523
524struct pardevice *
525parport_register_device(struct parport *port, const char *name,
526 int (*pf)(void *), void (*kf)(void *),
David Howells7d12e782006-10-05 14:55:46 +0100527 void (*irq_func)(int, void *),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 int flags, void *handle)
529{
530 struct pardevice *tmp;
531
532 if (port->physport->flags & PARPORT_FLAG_EXCL) {
533 /* An exclusive device is registered. */
534 printk (KERN_DEBUG "%s: no more devices allowed\n",
535 port->name);
536 return NULL;
537 }
538
539 if (flags & PARPORT_DEV_LURK) {
540 if (!pf || !kf) {
541 printk(KERN_INFO "%s: refused to register lurking device (%s) without callbacks\n", port->name, name);
542 return NULL;
543 }
544 }
545
546 /* We up our own module reference count, and that of the port
547 on which a device is to be registered, to ensure that
548 neither of us gets unloaded while we sleep in (e.g.)
549 kmalloc.
550 */
551 if (!try_module_get(port->ops->owner)) {
552 return NULL;
553 }
554
555 parport_get_port (port);
556
557 tmp = kmalloc(sizeof(struct pardevice), GFP_KERNEL);
558 if (tmp == NULL) {
559 printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name);
560 goto out;
561 }
562
563 tmp->state = kmalloc(sizeof(struct parport_state), GFP_KERNEL);
564 if (tmp->state == NULL) {
565 printk(KERN_WARNING "%s: memory squeeze, couldn't register %s.\n", port->name, name);
566 goto out_free_pardevice;
567 }
568
569 tmp->name = name;
570 tmp->port = port;
571 tmp->daisy = -1;
572 tmp->preempt = pf;
573 tmp->wakeup = kf;
574 tmp->private = handle;
575 tmp->flags = flags;
576 tmp->irq_func = irq_func;
577 tmp->waiting = 0;
578 tmp->timeout = 5 * HZ;
579
580 /* Chain this onto the list */
581 tmp->prev = NULL;
582 /*
583 * This function must not run from an irq handler so we don' t need
584 * to clear irq on the local CPU. -arca
585 */
586 spin_lock(&port->physport->pardevice_lock);
587
588 if (flags & PARPORT_DEV_EXCL) {
589 if (port->physport->devices) {
590 spin_unlock (&port->physport->pardevice_lock);
591 printk (KERN_DEBUG
592 "%s: cannot grant exclusive access for "
593 "device %s\n", port->name, name);
594 goto out_free_all;
595 }
596 port->flags |= PARPORT_FLAG_EXCL;
597 }
598
599 tmp->next = port->physport->devices;
600 wmb(); /* Make sure that tmp->next is written before it's
601 added to the list; see comments marked 'no locking
602 required' */
603 if (port->physport->devices)
604 port->physport->devices->prev = tmp;
605 port->physport->devices = tmp;
606 spin_unlock(&port->physport->pardevice_lock);
607
608 init_waitqueue_head(&tmp->wait_q);
609 tmp->timeslice = parport_default_timeslice;
610 tmp->waitnext = tmp->waitprev = NULL;
611
612 /*
613 * This has to be run as last thing since init_state may need other
614 * pardevice fields. -arca
615 */
616 port->ops->init_state(tmp, tmp->state);
617 parport_device_proc_register(tmp);
618 return tmp;
619
620 out_free_all:
Jesper Juhl6044ec82005-11-07 01:01:32 -0800621 kfree(tmp->state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 out_free_pardevice:
Jesper Juhl6044ec82005-11-07 01:01:32 -0800623 kfree(tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 out:
625 parport_put_port (port);
626 module_put(port->ops->owner);
627
628 return NULL;
629}
630
631/**
632 * parport_unregister_device - deregister a device on a parallel port
633 * @dev: pointer to structure representing device
634 *
635 * This undoes the effect of parport_register_device().
636 **/
637
638void parport_unregister_device(struct pardevice *dev)
639{
640 struct parport *port;
641
642#ifdef PARPORT_PARANOID
643 if (dev == NULL) {
644 printk(KERN_ERR "parport_unregister_device: passed NULL\n");
645 return;
646 }
647#endif
648
649 parport_device_proc_unregister(dev);
650
651 port = dev->port->physport;
652
653 if (port->cad == dev) {
654 printk(KERN_DEBUG "%s: %s forgot to release port\n",
655 port->name, dev->name);
656 parport_release (dev);
657 }
658
659 spin_lock(&port->pardevice_lock);
660 if (dev->next)
661 dev->next->prev = dev->prev;
662 if (dev->prev)
663 dev->prev->next = dev->next;
664 else
665 port->devices = dev->next;
666
667 if (dev->flags & PARPORT_DEV_EXCL)
668 port->flags &= ~PARPORT_FLAG_EXCL;
669
670 spin_unlock(&port->pardevice_lock);
671
672 /* Make sure we haven't left any pointers around in the wait
673 * list. */
674 spin_lock (&port->waitlist_lock);
675 if (dev->waitprev || dev->waitnext || port->waithead == dev) {
676 if (dev->waitprev)
677 dev->waitprev->waitnext = dev->waitnext;
678 else
679 port->waithead = dev->waitnext;
680 if (dev->waitnext)
681 dev->waitnext->waitprev = dev->waitprev;
682 else
683 port->waittail = dev->waitprev;
684 }
685 spin_unlock (&port->waitlist_lock);
686
687 kfree(dev->state);
688 kfree(dev);
689
690 module_put(port->ops->owner);
691 parport_put_port (port);
692}
693
694/**
695 * parport_find_number - find a parallel port by number
696 * @number: parallel port number
697 *
698 * This returns the parallel port with the specified number, or
699 * %NULL if there is none.
700 *
701 * There is an implicit parport_get_port() done already; to throw
702 * away the reference to the port that parport_find_number()
703 * gives you, use parport_put_port().
704 */
705
706struct parport *parport_find_number (int number)
707{
708 struct parport *port, *result = NULL;
709
710 if (list_empty(&portlist))
711 get_lowlevel_driver ();
712
713 spin_lock (&parportlist_lock);
714 list_for_each_entry(port, &portlist, list) {
715 if (port->number == number) {
716 result = parport_get_port (port);
717 break;
718 }
719 }
720 spin_unlock (&parportlist_lock);
721 return result;
722}
723
724/**
725 * parport_find_base - find a parallel port by base address
726 * @base: base I/O address
727 *
728 * This returns the parallel port with the specified base
729 * address, or %NULL if there is none.
730 *
731 * There is an implicit parport_get_port() done already; to throw
732 * away the reference to the port that parport_find_base()
733 * gives you, use parport_put_port().
734 */
735
736struct parport *parport_find_base (unsigned long base)
737{
738 struct parport *port, *result = NULL;
739
740 if (list_empty(&portlist))
741 get_lowlevel_driver ();
742
743 spin_lock (&parportlist_lock);
744 list_for_each_entry(port, &portlist, list) {
745 if (port->base == base) {
746 result = parport_get_port (port);
747 break;
748 }
749 }
750 spin_unlock (&parportlist_lock);
751 return result;
752}
753
754/**
755 * parport_claim - claim access to a parallel port device
756 * @dev: pointer to structure representing a device on the port
757 *
758 * This function will not block and so can be used from interrupt
759 * context. If parport_claim() succeeds in claiming access to
760 * the port it returns zero and the port is available to use. It
761 * may fail (returning non-zero) if the port is in use by another
762 * driver and that driver is not willing to relinquish control of
763 * the port.
764 **/
765
766int parport_claim(struct pardevice *dev)
767{
768 struct pardevice *oldcad;
769 struct parport *port = dev->port->physport;
770 unsigned long flags;
771
772 if (port->cad == dev) {
773 printk(KERN_INFO "%s: %s already owner\n",
774 dev->port->name,dev->name);
775 return 0;
776 }
777
778 /* Preempt any current device */
779 write_lock_irqsave (&port->cad_lock, flags);
780 if ((oldcad = port->cad) != NULL) {
781 if (oldcad->preempt) {
782 if (oldcad->preempt(oldcad->private))
783 goto blocked;
784 port->ops->save_state(port, dev->state);
785 } else
786 goto blocked;
787
788 if (port->cad != oldcad) {
789 /* I think we'll actually deadlock rather than
790 get here, but just in case.. */
791 printk(KERN_WARNING
792 "%s: %s released port when preempted!\n",
793 port->name, oldcad->name);
794 if (port->cad)
795 goto blocked;
796 }
797 }
798
799 /* Can't fail from now on, so mark ourselves as no longer waiting. */
800 if (dev->waiting & 1) {
801 dev->waiting = 0;
802
803 /* Take ourselves out of the wait list again. */
804 spin_lock_irq (&port->waitlist_lock);
805 if (dev->waitprev)
806 dev->waitprev->waitnext = dev->waitnext;
807 else
808 port->waithead = dev->waitnext;
809 if (dev->waitnext)
810 dev->waitnext->waitprev = dev->waitprev;
811 else
812 port->waittail = dev->waitprev;
813 spin_unlock_irq (&port->waitlist_lock);
814 dev->waitprev = dev->waitnext = NULL;
815 }
816
817 /* Now we do the change of devices */
818 port->cad = dev;
819
820#ifdef CONFIG_PARPORT_1284
821 /* If it's a mux port, select it. */
822 if (dev->port->muxport >= 0) {
823 /* FIXME */
824 port->muxsel = dev->port->muxport;
825 }
826
827 /* If it's a daisy chain device, select it. */
828 if (dev->daisy >= 0) {
829 /* This could be lazier. */
830 if (!parport_daisy_select (port, dev->daisy,
831 IEEE1284_MODE_COMPAT))
832 port->daisy = dev->daisy;
833 }
834#endif /* IEEE1284.3 support */
835
836 /* Restore control registers */
837 port->ops->restore_state(port, dev->state);
838 write_unlock_irqrestore(&port->cad_lock, flags);
839 dev->time = jiffies;
840 return 0;
841
842blocked:
843 /* If this is the first time we tried to claim the port, register an
844 interest. This is only allowed for devices sleeping in
845 parport_claim_or_block(), or those with a wakeup function. */
846
847 /* The cad_lock is still held for writing here */
848 if (dev->waiting & 2 || dev->wakeup) {
849 spin_lock (&port->waitlist_lock);
850 if (test_and_set_bit(0, &dev->waiting) == 0) {
851 /* First add ourselves to the end of the wait list. */
852 dev->waitnext = NULL;
853 dev->waitprev = port->waittail;
854 if (port->waittail) {
855 port->waittail->waitnext = dev;
856 port->waittail = dev;
857 } else
858 port->waithead = port->waittail = dev;
859 }
860 spin_unlock (&port->waitlist_lock);
861 }
862 write_unlock_irqrestore (&port->cad_lock, flags);
863 return -EAGAIN;
864}
865
866/**
867 * parport_claim_or_block - claim access to a parallel port device
868 * @dev: pointer to structure representing a device on the port
869 *
870 * This behaves like parport_claim(), but will block if necessary
871 * to wait for the port to be free. A return value of 1
872 * indicates that it slept; 0 means that it succeeded without
873 * needing to sleep. A negative error code indicates failure.
874 **/
875
876int parport_claim_or_block(struct pardevice *dev)
877{
878 int r;
879
880 /* Signal to parport_claim() that we can wait even without a
881 wakeup function. */
882 dev->waiting = 2;
883
884 /* Try to claim the port. If this fails, we need to sleep. */
885 r = parport_claim(dev);
886 if (r == -EAGAIN) {
887#ifdef PARPORT_DEBUG_SHARING
888 printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n", dev->name);
889#endif
890 /*
891 * FIXME!!! Use the proper locking for dev->waiting,
892 * and make this use the "wait_event_interruptible()"
893 * interfaces. The cli/sti that used to be here
894 * did nothing.
895 *
896 * See also parport_release()
897 */
898
899 /* If dev->waiting is clear now, an interrupt
900 gave us the port and we would deadlock if we slept. */
901 if (dev->waiting) {
902 interruptible_sleep_on (&dev->wait_q);
903 if (signal_pending (current)) {
904 return -EINTR;
905 }
906 r = 1;
907 } else {
908 r = 0;
909#ifdef PARPORT_DEBUG_SHARING
910 printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
911 dev->name);
912#endif
913 }
914
915#ifdef PARPORT_DEBUG_SHARING
916 if (dev->port->physport->cad != dev)
917 printk(KERN_DEBUG "%s: exiting parport_claim_or_block "
918 "but %s owns port!\n", dev->name,
919 dev->port->physport->cad ?
920 dev->port->physport->cad->name:"nobody");
921#endif
922 }
923 dev->waiting = 0;
924 return r;
925}
926
927/**
928 * parport_release - give up access to a parallel port device
929 * @dev: pointer to structure representing parallel port device
930 *
931 * This function cannot fail, but it should not be called without
932 * the port claimed. Similarly, if the port is already claimed
933 * you should not try claiming it again.
934 **/
935
936void parport_release(struct pardevice *dev)
937{
938 struct parport *port = dev->port->physport;
939 struct pardevice *pd;
940 unsigned long flags;
941
942 /* Make sure that dev is the current device */
943 write_lock_irqsave(&port->cad_lock, flags);
944 if (port->cad != dev) {
945 write_unlock_irqrestore (&port->cad_lock, flags);
946 printk(KERN_WARNING "%s: %s tried to release parport "
947 "when not owner\n", port->name, dev->name);
948 return;
949 }
950
951#ifdef CONFIG_PARPORT_1284
952 /* If this is on a mux port, deselect it. */
953 if (dev->port->muxport >= 0) {
954 /* FIXME */
955 port->muxsel = -1;
956 }
957
958 /* If this is a daisy device, deselect it. */
959 if (dev->daisy >= 0) {
960 parport_daisy_deselect_all (port);
961 port->daisy = -1;
962 }
963#endif
964
965 port->cad = NULL;
966 write_unlock_irqrestore(&port->cad_lock, flags);
967
968 /* Save control registers */
969 port->ops->save_state(port, dev->state);
970
971 /* If anybody is waiting, find out who's been there longest and
972 then wake them up. (Note: no locking required) */
973 /* !!! LOCKING IS NEEDED HERE */
974 for (pd = port->waithead; pd; pd = pd->waitnext) {
975 if (pd->waiting & 2) { /* sleeping in claim_or_block */
976 parport_claim(pd);
977 if (waitqueue_active(&pd->wait_q))
978 wake_up_interruptible(&pd->wait_q);
979 return;
980 } else if (pd->wakeup) {
981 pd->wakeup(pd->private);
982 if (dev->port->cad) /* racy but no matter */
983 return;
984 } else {
985 printk(KERN_ERR "%s: don't know how to wake %s\n", port->name, pd->name);
986 }
987 }
988
989 /* Nobody was waiting, so walk the list to see if anyone is
990 interested in being woken up. (Note: no locking required) */
991 /* !!! LOCKING IS NEEDED HERE */
992 for (pd = port->devices; (port->cad == NULL) && pd; pd = pd->next) {
993 if (pd->wakeup && pd != dev)
994 pd->wakeup(pd->private);
995 }
996}
997
998/* Exported symbols for modules. */
999
1000EXPORT_SYMBOL(parport_claim);
1001EXPORT_SYMBOL(parport_claim_or_block);
1002EXPORT_SYMBOL(parport_release);
1003EXPORT_SYMBOL(parport_register_port);
1004EXPORT_SYMBOL(parport_announce_port);
1005EXPORT_SYMBOL(parport_remove_port);
1006EXPORT_SYMBOL(parport_register_driver);
1007EXPORT_SYMBOL(parport_unregister_driver);
1008EXPORT_SYMBOL(parport_register_device);
1009EXPORT_SYMBOL(parport_unregister_device);
Marko Kohtala94b82092006-01-06 00:19:51 -08001010EXPORT_SYMBOL(parport_get_port);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011EXPORT_SYMBOL(parport_put_port);
1012EXPORT_SYMBOL(parport_find_number);
1013EXPORT_SYMBOL(parport_find_base);
1014
1015MODULE_LICENSE("GPL");