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/drivers/parport/share.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 1032 lines | 568 code | 133 blank | 331 comment | 99 complexity | ffbd2f3b168ce4cd8930659f99703385 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
   1/*
   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/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>
  34#include <linux/mutex.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 DEFINE_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	mutex_lock(&registration_lock);
 162	list_for_each_entry(port, &portlist, list)
 163		drv->attach(port);
 164	list_add(&drv->list, &drivers);
 165	mutex_unlock(&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	mutex_lock(&registration_lock);
 192	list_del_init(&drv->list);
 193	list_for_each_entry(port, &portlist, list)
 194		drv->detach(port);
 195	mutex_unlock(&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++) {
 205		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);
 210	}
 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 ensures 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	sema_init(&tmp->ieee1284.irq, 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	if (!port->dev)
 369		printk(KERN_WARNING "%s: fix this legacy "
 370				"no-device port driver!\n",
 371				port->name);
 372
 373	parport_proc_register(port);
 374	mutex_lock(&registration_lock);
 375	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	}
 391	mutex_unlock(&registration_lock);
 392}
 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
 417	mutex_lock(&registration_lock);
 418
 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
 444	mutex_unlock(&registration_lock);
 445
 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 *),
 527			void (*irq_func)(void *), 
 528			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	if (!test_and_set_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags)) {
 618		port->proc_device = tmp;
 619		parport_device_proc_register(tmp);
 620	}
 621	return tmp;
 622
 623 out_free_all:
 624	kfree(tmp->state);
 625 out_free_pardevice:
 626	kfree(tmp);
 627 out:
 628	parport_put_port (port);
 629	module_put(port->ops->owner);
 630
 631	return NULL;
 632}
 633
 634/**
 635 *	parport_unregister_device - deregister a device on a parallel port
 636 *	@dev: pointer to structure representing device
 637 *
 638 *	This undoes the effect of parport_register_device().
 639 **/
 640
 641void parport_unregister_device(struct pardevice *dev)
 642{
 643	struct parport *port;
 644
 645#ifdef PARPORT_PARANOID
 646	if (dev == NULL) {
 647		printk(KERN_ERR "parport_unregister_device: passed NULL\n");
 648		return;
 649	}
 650#endif
 651
 652	port = dev->port->physport;
 653
 654	if (port->proc_device == dev) {
 655		port->proc_device = NULL;
 656		clear_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags);
 657		parport_device_proc_unregister(dev);
 658	}
 659
 660	if (port->cad == dev) {
 661		printk(KERN_DEBUG "%s: %s forgot to release port\n",
 662		       port->name, dev->name);
 663		parport_release (dev);
 664	}
 665
 666	spin_lock(&port->pardevice_lock);
 667	if (dev->next)
 668		dev->next->prev = dev->prev;
 669	if (dev->prev)
 670		dev->prev->next = dev->next;
 671	else
 672		port->devices = dev->next;
 673
 674	if (dev->flags & PARPORT_DEV_EXCL)
 675		port->flags &= ~PARPORT_FLAG_EXCL;
 676
 677	spin_unlock(&port->pardevice_lock);
 678
 679	/* Make sure we haven't left any pointers around in the wait
 680	 * list. */
 681	spin_lock_irq(&port->waitlist_lock);
 682	if (dev->waitprev || dev->waitnext || port->waithead == dev) {
 683		if (dev->waitprev)
 684			dev->waitprev->waitnext = dev->waitnext;
 685		else
 686			port->waithead = dev->waitnext;
 687		if (dev->waitnext)
 688			dev->waitnext->waitprev = dev->waitprev;
 689		else
 690			port->waittail = dev->waitprev;
 691	}
 692	spin_unlock_irq(&port->waitlist_lock);
 693
 694	kfree(dev->state);
 695	kfree(dev);
 696
 697	module_put(port->ops->owner);
 698	parport_put_port (port);
 699}
 700
 701/**
 702 *	parport_find_number - find a parallel port by number
 703 *	@number: parallel port number
 704 *
 705 *	This returns the parallel port with the specified number, or
 706 *	%NULL if there is none.
 707 *
 708 *	There is an implicit parport_get_port() done already; to throw
 709 *	away the reference to the port that parport_find_number()
 710 *	gives you, use parport_put_port().
 711 */
 712
 713struct parport *parport_find_number (int number)
 714{
 715	struct parport *port, *result = NULL;
 716
 717	if (list_empty(&portlist))
 718		get_lowlevel_driver ();
 719
 720	spin_lock (&parportlist_lock);
 721	list_for_each_entry(port, &portlist, list) {
 722		if (port->number == number) {
 723			result = parport_get_port (port);
 724			break;
 725		}
 726	}
 727	spin_unlock (&parportlist_lock);
 728	return result;
 729}
 730
 731/**
 732 *	parport_find_base - find a parallel port by base address
 733 *	@base: base I/O address
 734 *
 735 *	This returns the parallel port with the specified base
 736 *	address, or %NULL if there is none.
 737 *
 738 *	There is an implicit parport_get_port() done already; to throw
 739 *	away the reference to the port that parport_find_base()
 740 *	gives you, use parport_put_port().
 741 */
 742
 743struct parport *parport_find_base (unsigned long base)
 744{
 745	struct parport *port, *result = NULL;
 746
 747	if (list_empty(&portlist))
 748		get_lowlevel_driver ();
 749
 750	spin_lock (&parportlist_lock);
 751	list_for_each_entry(port, &portlist, list) {
 752		if (port->base == base) {
 753			result = parport_get_port (port);
 754			break;
 755		}
 756	}
 757	spin_unlock (&parportlist_lock);
 758	return result;
 759}
 760
 761/**
 762 *	parport_claim - claim access to a parallel port device
 763 *	@dev: pointer to structure representing a device on the port
 764 *
 765 *	This function will not block and so can be used from interrupt
 766 *	context.  If parport_claim() succeeds in claiming access to
 767 *	the port it returns zero and the port is available to use.  It
 768 *	may fail (returning non-zero) if the port is in use by another
 769 *	driver and that driver is not willing to relinquish control of
 770 *	the port.
 771 **/
 772
 773int parport_claim(struct pardevice *dev)
 774{
 775	struct pardevice *oldcad;
 776	struct parport *port = dev->port->physport;
 777	unsigned long flags;
 778
 779	if (port->cad == dev) {
 780		printk(KERN_INFO "%s: %s already owner\n",
 781		       dev->port->name,dev->name);
 782		return 0;
 783	}
 784
 785	/* Preempt any current device */
 786	write_lock_irqsave (&port->cad_lock, flags);
 787	if ((oldcad = port->cad) != NULL) {
 788		if (oldcad->preempt) {
 789			if (oldcad->preempt(oldcad->private))
 790				goto blocked;
 791			port->ops->save_state(port, dev->state);
 792		} else
 793			goto blocked;
 794
 795		if (port->cad != oldcad) {
 796			/* I think we'll actually deadlock rather than
 797                           get here, but just in case.. */
 798			printk(KERN_WARNING
 799			       "%s: %s released port when preempted!\n",
 800			       port->name, oldcad->name);
 801			if (port->cad)
 802				goto blocked;
 803		}
 804	}
 805
 806	/* Can't fail from now on, so mark ourselves as no longer waiting.  */
 807	if (dev->waiting & 1) {
 808		dev->waiting = 0;
 809
 810		/* Take ourselves out of the wait list again.  */
 811		spin_lock_irq (&port->waitlist_lock);
 812		if (dev->waitprev)
 813			dev->waitprev->waitnext = dev->waitnext;
 814		else
 815			port->waithead = dev->waitnext;
 816		if (dev->waitnext)
 817			dev->waitnext->waitprev = dev->waitprev;
 818		else
 819			port->waittail = dev->waitprev;
 820		spin_unlock_irq (&port->waitlist_lock);
 821		dev->waitprev = dev->waitnext = NULL;
 822	}
 823
 824	/* Now we do the change of devices */
 825	port->cad = dev;
 826
 827#ifdef CONFIG_PARPORT_1284
 828	/* If it's a mux port, select it. */
 829	if (dev->port->muxport >= 0) {
 830		/* FIXME */
 831		port->muxsel = dev->port->muxport;
 832	}
 833
 834	/* If it's a daisy chain device, select it. */
 835	if (dev->daisy >= 0) {
 836		/* This could be lazier. */
 837		if (!parport_daisy_select (port, dev->daisy,
 838					   IEEE1284_MODE_COMPAT))
 839			port->daisy = dev->daisy;
 840	}
 841#endif /* IEEE1284.3 support */
 842
 843	/* Restore control registers */
 844	port->ops->restore_state(port, dev->state);
 845	write_unlock_irqrestore(&port->cad_lock, flags);
 846	dev->time = jiffies;
 847	return 0;
 848
 849blocked:
 850	/* If this is the first time we tried to claim the port, register an
 851	   interest.  This is only allowed for devices sleeping in
 852	   parport_claim_or_block(), or those with a wakeup function.  */
 853
 854	/* The cad_lock is still held for writing here */
 855	if (dev->waiting & 2 || dev->wakeup) {
 856		spin_lock (&port->waitlist_lock);
 857		if (test_and_set_bit(0, &dev->waiting) == 0) {
 858			/* First add ourselves to the end of the wait list. */
 859			dev->waitnext = NULL;
 860			dev->waitprev = port->waittail;
 861			if (port->waittail) {
 862				port->waittail->waitnext = dev;
 863				port->waittail = dev;
 864			} else
 865				port->waithead = port->waittail = dev;
 866		}
 867		spin_unlock (&port->waitlist_lock);
 868	}
 869	write_unlock_irqrestore (&port->cad_lock, flags);
 870	return -EAGAIN;
 871}
 872
 873/**
 874 *	parport_claim_or_block - claim access to a parallel port device
 875 *	@dev: pointer to structure representing a device on the port
 876 *
 877 *	This behaves like parport_claim(), but will block if necessary
 878 *	to wait for the port to be free.  A return value of 1
 879 *	indicates that it slept; 0 means that it succeeded without
 880 *	needing to sleep.  A negative error code indicates failure.
 881 **/
 882
 883int parport_claim_or_block(struct pardevice *dev)
 884{
 885	int r;
 886
 887	/* Signal to parport_claim() that we can wait even without a
 888	   wakeup function.  */
 889	dev->waiting = 2;
 890
 891	/* Try to claim the port.  If this fails, we need to sleep.  */
 892	r = parport_claim(dev);
 893	if (r == -EAGAIN) {
 894#ifdef PARPORT_DEBUG_SHARING
 895		printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n", dev->name);
 896#endif
 897		/*
 898		 * FIXME!!! Use the proper locking for dev->waiting,
 899		 * and make this use the "wait_event_interruptible()"
 900		 * interfaces. The cli/sti that used to be here
 901		 * did nothing.
 902		 *
 903		 * See also parport_release()
 904		 */
 905
 906		/* If dev->waiting is clear now, an interrupt
 907		   gave us the port and we would deadlock if we slept.  */
 908		if (dev->waiting) {
 909			interruptible_sleep_on (&dev->wait_q);
 910			if (signal_pending (current)) {
 911				return -EINTR;
 912			}
 913			r = 1;
 914		} else {
 915			r = 0;
 916#ifdef PARPORT_DEBUG_SHARING
 917			printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
 918			       dev->name);
 919#endif
 920		}
 921
 922#ifdef PARPORT_DEBUG_SHARING
 923		if (dev->port->physport->cad != dev)
 924			printk(KERN_DEBUG "%s: exiting parport_claim_or_block "
 925			       "but %s owns port!\n", dev->name,
 926			       dev->port->physport->cad ?
 927			       dev->port->physport->cad->name:"nobody");
 928#endif
 929	}
 930	dev->waiting = 0;
 931	return r;
 932}
 933
 934/**
 935 *	parport_release - give up access to a parallel port device
 936 *	@dev: pointer to structure representing parallel port device
 937 *
 938 *	This function cannot fail, but it should not be called without
 939 *	the port claimed.  Similarly, if the port is already claimed
 940 *	you should not try claiming it again.
 941 **/
 942
 943void parport_release(struct pardevice *dev)
 944{
 945	struct parport *port = dev->port->physport;
 946	struct pardevice *pd;
 947	unsigned long flags;
 948
 949	/* Make sure that dev is the current device */
 950	write_lock_irqsave(&port->cad_lock, flags);
 951	if (port->cad != dev) {
 952		write_unlock_irqrestore (&port->cad_lock, flags);
 953		printk(KERN_WARNING "%s: %s tried to release parport "
 954		       "when not owner\n", port->name, dev->name);
 955		return;
 956	}
 957
 958#ifdef CONFIG_PARPORT_1284
 959	/* If this is on a mux port, deselect it. */
 960	if (dev->port->muxport >= 0) {
 961		/* FIXME */
 962		port->muxsel = -1;
 963	}
 964
 965	/* If this is a daisy device, deselect it. */
 966	if (dev->daisy >= 0) {
 967		parport_daisy_deselect_all (port);
 968		port->daisy = -1;
 969	}
 970#endif
 971
 972	port->cad = NULL;
 973	write_unlock_irqrestore(&port->cad_lock, flags);
 974
 975	/* Save control registers */
 976	port->ops->save_state(port, dev->state);
 977
 978	/* If anybody is waiting, find out who's been there longest and
 979	   then wake them up. (Note: no locking required) */
 980	/* !!! LOCKING IS NEEDED HERE */
 981	for (pd = port->waithead; pd; pd = pd->waitnext) {
 982		if (pd->waiting & 2) { /* sleeping in claim_or_block */
 983			parport_claim(pd);
 984			if (waitqueue_active(&pd->wait_q))
 985				wake_up_interruptible(&pd->wait_q);
 986			return;
 987		} else if (pd->wakeup) {
 988			pd->wakeup(pd->private);
 989			if (dev->port->cad) /* racy but no matter */
 990				return;
 991		} else {
 992			printk(KERN_ERR "%s: don't know how to wake %s\n", port->name, pd->name);
 993		}
 994	}
 995
 996	/* Nobody was waiting, so walk the list to see if anyone is
 997	   interested in being woken up. (Note: no locking required) */
 998	/* !!! LOCKING IS NEEDED HERE */
 999	for (pd = port->devices; (port->cad == NULL) && pd; pd = pd->next) {
1000		if (pd->wakeup && pd != dev)
1001			pd->wakeup(pd->private);
1002	}
1003}
1004
1005irqreturn_t parport_irq_handler(int irq, void *dev_id)
1006{
1007	struct parport *port = dev_id;
1008
1009	parport_generic_irq(port);
1010
1011	return IRQ_HANDLED;
1012}
1013
1014/* Exported symbols for modules. */
1015
1016EXPORT_SYMBOL(parport_claim);
1017EXPORT_SYMBOL(parport_claim_or_block);
1018EXPORT_SYMBOL(parport_release);
1019EXPORT_SYMBOL(parport_register_port);
1020EXPORT_SYMBOL(parport_announce_port);
1021EXPORT_SYMBOL(parport_remove_port);
1022EXPORT_SYMBOL(parport_register_driver);
1023EXPORT_SYMBOL(parport_unregister_driver);
1024EXPORT_SYMBOL(parport_register_device);
1025EXPORT_SYMBOL(parport_unregister_device);
1026EXPORT_SYMBOL(parport_get_port);
1027EXPORT_SYMBOL(parport_put_port);
1028EXPORT_SYMBOL(parport_find_number);
1029EXPORT_SYMBOL(parport_find_base);
1030EXPORT_SYMBOL(parport_irq_handler);
1031
1032MODULE_LICENSE("GPL");