linux/drivers/parport/share.c
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   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");
1033
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