drivers/gpu/vga/vgaarb.c

   1 /*
   2  * vgaarb.c
   3  *
   4  * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
   5  * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
   6  * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
   7  *
   8  * Implements the VGA arbitration. For details refer to
   9  * Documentation/vgaarbiter.txt
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/pci.h>
  15 #include <linux/errno.h>
  16 #include <linux/init.h>
  17 #include <linux/list.h>
  18 #include <linux/sched.h>
  19 #include <linux/wait.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/poll.h>
  22 #include <linux/miscdevice.h>
  23
  24 #include <linux/uaccess.h>
  25
  26 #include <linux/vgaarb.h>
  27
  28 static void vga_arbiter_notify_clients(void);
  29 /*
  30  * We keep a list of all vga devices in the system to speed
  31  * up the various operations of the arbiter
  32  */
  33 struct vga_device {
  34         struct list_head list;
  35         struct pci_dev *pdev;
  36         unsigned int decodes;   /* what does it decodes */
  37         unsigned int owns;      /* what does it owns */
  38         unsigned int locks;     /* what does it locks */
  39         unsigned int io_lock_cnt;       /* legacy IO lock count */
  40         unsigned int mem_lock_cnt;      /* legacy MEM lock count */
  41         unsigned int io_norm_cnt;       /* normal IO count */
  42         unsigned int mem_norm_cnt;      /* normal MEM count */
  43
  44         /* allow IRQ enable/disable hook */
  45         void *cookie;
  46         void (*irq_set_state)(void *cookie, bool enable);
  47         unsigned int (*set_vga_decode)(void *cookie, bool decode);
  48 };
  49
  50 static LIST_HEAD(vga_list);
  51 static int vga_count, vga_decode_count;
  52 static bool vga_arbiter_used;
  53 static DEFINE_SPINLOCK(vga_lock);
  54 static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
  55
  56
  57 static const char *vga_iostate_to_str(unsigned int iostate)
  58 {
  59         /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
  60         iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
  61         switch (iostate) {
  62         case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
  63                 return "io+mem";
  64         case VGA_RSRC_LEGACY_IO:
  65                 return "io";
  66         case VGA_RSRC_LEGACY_MEM:
  67                 return "mem";
  68         }
  69         return "none";
  70 }
  71
  72 static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
  73 {
  74         /* we could in theory hand out locks on IO and mem
  75          * separately to userspace but it can cause deadlocks */
  76         if (strncmp(buf, "none", 4) == 0) {
  77                 *io_state = VGA_RSRC_NONE;
  78                 return 1;
  79         }
  80
  81         /* XXX We're not chekcing the str_size! */
  82         if (strncmp(buf, "io+mem", 6) == 0)
  83                 goto both;
  84         else if (strncmp(buf, "io", 2) == 0)
  85                 goto both;
  86         else if (strncmp(buf, "mem", 3) == 0)
  87                 goto both;
  88         return 0;
  89 both:
  90         *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
  91         return 1;
  92 }
  93
  94 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
  95 /* this is only used a cookie - it should not be dereferenced */
  96 static struct pci_dev *vga_default;
  97 #endif
  98
  99 static void vga_arb_device_card_gone(struct pci_dev *pdev);
 100
 101 /* Find somebody in our list */
 102 static struct vga_device *vgadev_find(struct pci_dev *pdev)
 103 {
 104         struct vga_device *vgadev;
 105
 106         list_for_each_entry(vgadev, &vga_list, list)
 107                 if (pdev == vgadev->pdev)
 108                         return vgadev;
 109         return NULL;
 110 }
 111
 112 /* Returns the default VGA device (vgacon's babe) */
 113 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 114 struct pci_dev *vga_default_device(void)
 115 {
 116         return vga_default;
 117 }
 118 #endif
 119
 120 static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
 121 {
 122         if (vgadev->irq_set_state)
 123                 vgadev->irq_set_state(vgadev->cookie, state);
 124 }
 125
 126
 127 /* If we don't ever use VGA arb we should avoid
 128    turning off anything anywhere due to old X servers getting
 129    confused about the boot device not being VGA */
 130 static void vga_check_first_use(void)
 131 {
 132         /* we should inform all GPUs in the system that
 133          * VGA arb has occured and to try and disable resources
 134          * if they can */
 135         if (!vga_arbiter_used) {
 136                 vga_arbiter_used = true;
 137                 vga_arbiter_notify_clients();
 138         }
 139 }
 140
 141 static struct vga_device *__vga_tryget(struct vga_device *vgadev,
 142                                        unsigned int rsrc)
 143 {
 144         unsigned int wants, legacy_wants, match;
 145         struct vga_device *conflict;
 146         unsigned int pci_bits;
 147         /* Account for "normal" resources to lock. If we decode the legacy,
 148          * counterpart, we need to request it as well
 149          */
 150         if ((rsrc & VGA_RSRC_NORMAL_IO) &&
 151             (vgadev->decodes & VGA_RSRC_LEGACY_IO))
 152                 rsrc |= VGA_RSRC_LEGACY_IO;
 153         if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
 154             (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
 155                 rsrc |= VGA_RSRC_LEGACY_MEM;
 156
 157         pr_devel("%s: %d\n", __func__, rsrc);
 158         pr_devel("%s: owns: %d\n", __func__, vgadev->owns);
 159
 160         /* Check what resources we need to acquire */
 161         wants = rsrc & ~vgadev->owns;
 162
 163         /* We already own everything, just mark locked & bye bye */
 164         if (wants == 0)
 165                 goto lock_them;
 166
 167         /* We don't need to request a legacy resource, we just enable
 168          * appropriate decoding and go
 169          */
 170         legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
 171         if (legacy_wants == 0)
 172                 goto enable_them;
 173
 174         /* Ok, we don't, let's find out how we need to kick off */
 175         list_for_each_entry(conflict, &vga_list, list) {
 176                 unsigned int lwants = legacy_wants;
 177                 unsigned int change_bridge = 0;
 178
 179                 /* Don't conflict with myself */
 180                 if (vgadev == conflict)
 181                         continue;
 182
 183                 /* Check if the architecture allows a conflict between those
 184                  * 2 devices or if they are on separate domains
 185                  */
 186                 if (!vga_conflicts(vgadev->pdev, conflict->pdev))
 187                         continue;
 188
 189                 /* We have a possible conflict. before we go further, we must
 190                  * check if we sit on the same bus as the conflicting device.
 191                  * if we don't, then we must tie both IO and MEM resources
 192                  * together since there is only a single bit controlling
 193                  * VGA forwarding on P2P bridges
 194                  */
 195                 if (vgadev->pdev->bus != conflict->pdev->bus) {
 196                         change_bridge = 1;
 197                         lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
 198                 }
 199
 200                 /* Check if the guy has a lock on the resource. If he does,
 201                  * return the conflicting entry
 202                  */
 203                 if (conflict->locks & lwants)
 204                         return conflict;
 205
 206                 /* Ok, now check if he owns the resource we want. We don't need
 207                  * to check "decodes" since it should be impossible to own
 208                  * own legacy resources you don't decode unless I have a bug
 209                  * in this code...
 210                  */
 211                 WARN_ON(conflict->owns & ~conflict->decodes);
 212                 match = lwants & conflict->owns;
 213                 if (!match)
 214                         continue;
 215
 216                 /* looks like he doesn't have a lock, we can steal
 217                  * them from him
 218                  */
 219                 vga_irq_set_state(conflict, false);
 220
 221                 pci_bits = 0;
 222                 if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
 223                         pci_bits |= PCI_COMMAND_MEMORY;
 224                 if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
 225                         pci_bits |= PCI_COMMAND_IO;
 226
 227                 pci_set_vga_state(conflict->pdev, false, pci_bits,
 228                                   change_bridge);
 229                 conflict->owns &= ~lwants;
 230                 /* If he also owned non-legacy, that is no longer the case */
 231                 if (lwants & VGA_RSRC_LEGACY_MEM)
 232                         conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
 233                 if (lwants & VGA_RSRC_LEGACY_IO)
 234                         conflict->owns &= ~VGA_RSRC_NORMAL_IO;
 235         }
 236
 237 enable_them:
 238         /* ok dude, we got it, everybody conflicting has been disabled, let's
 239          * enable us. Make sure we don't mark a bit in "owns" that we don't
 240          * also have in "decodes". We can lock resources we don't decode but
 241          * not own them.
 242          */
 243         pci_bits = 0;
 244         if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
 245                 pci_bits |= PCI_COMMAND_MEMORY;
 246         if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
 247                 pci_bits |= PCI_COMMAND_IO;
 248         pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
 249
 250         vga_irq_set_state(vgadev, true);
 251         vgadev->owns |= (wants & vgadev->decodes);
 252 lock_them:
 253         vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
 254         if (rsrc & VGA_RSRC_LEGACY_IO)
 255                 vgadev->io_lock_cnt++;
 256         if (rsrc & VGA_RSRC_LEGACY_MEM)
 257                 vgadev->mem_lock_cnt++;
 258         if (rsrc & VGA_RSRC_NORMAL_IO)
 259                 vgadev->io_norm_cnt++;
 260         if (rsrc & VGA_RSRC_NORMAL_MEM)
 261                 vgadev->mem_norm_cnt++;
 262
 263         return NULL;
 264 }
 265
 266 static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
 267 {
 268         unsigned int old_locks = vgadev->locks;
 269
 270         pr_devel("%s\n", __func__);
 271
 272         /* Update our counters, and account for equivalent legacy resources
 273          * if we decode them
 274          */
 275         if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
 276                 vgadev->io_norm_cnt--;
 277                 if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
 278                         rsrc |= VGA_RSRC_LEGACY_IO;
 279         }
 280         if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
 281                 vgadev->mem_norm_cnt--;
 282                 if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
 283                         rsrc |= VGA_RSRC_LEGACY_MEM;
 284         }
 285         if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
 286                 vgadev->io_lock_cnt--;
 287         if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
 288                 vgadev->mem_lock_cnt--;
 289
 290         /* Just clear lock bits, we do lazy operations so we don't really
 291          * have to bother about anything else at this point
 292          */
 293         if (vgadev->io_lock_cnt == 0)
 294                 vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
 295         if (vgadev->mem_lock_cnt == 0)
 296                 vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
 297
 298         /* Kick the wait queue in case somebody was waiting if we actually
 299          * released something
 300          */
 301         if (old_locks != vgadev->locks)
 302                 wake_up_all(&vga_wait_queue);
 303 }
 304
 305 int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
 306 {
 307         struct vga_device *vgadev, *conflict;
 308         unsigned long flags;
 309         wait_queue_t wait;
 310         int rc = 0;
 311
 312         vga_check_first_use();
 313         /* The one who calls us should check for this, but lets be sure... */
 314         if (pdev == NULL)
 315                 pdev = vga_default_device();
 316         if (pdev == NULL)
 317                 return 0;
 318
 319         for (;;) {
 320                 spin_lock_irqsave(&vga_lock, flags);
 321                 vgadev = vgadev_find(pdev);
 322                 if (vgadev == NULL) {
 323                         spin_unlock_irqrestore(&vga_lock, flags);
 324                         rc = -ENODEV;
 325                         break;
 326                 }
 327                 conflict = __vga_tryget(vgadev, rsrc);
 328                 spin_unlock_irqrestore(&vga_lock, flags);
 329                 if (conflict == NULL)
 330                         break;
 331
 332
 333                 /* We have a conflict, we wait until somebody kicks the
 334                  * work queue. Currently we have one work queue that we
 335                  * kick each time some resources are released, but it would
 336                  * be fairly easy to have a per device one so that we only
 337                  * need to attach to the conflicting device
 338                  */
 339                 init_waitqueue_entry(&wait, current);
 340                 add_wait_queue(&vga_wait_queue, &wait);
 341                 set_current_state(interruptible ?
 342                                   TASK_INTERRUPTIBLE :
 343                                   TASK_UNINTERRUPTIBLE);
 344                 if (signal_pending(current)) {
 345                         rc = -EINTR;
 346                         break;
 347                 }
 348                 schedule();
 349                 remove_wait_queue(&vga_wait_queue, &wait);
 350                 set_current_state(TASK_RUNNING);
 351         }
 352         return rc;
 353 }
 354 EXPORT_SYMBOL(vga_get);
 355
 356 int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
 357 {
 358         struct vga_device *vgadev;
 359         unsigned long flags;
 360         int rc = 0;
 361
 362         vga_check_first_use();
 363
 364         /* The one who calls us should check for this, but lets be sure... */
 365         if (pdev == NULL)
 366                 pdev = vga_default_device();
 367         if (pdev == NULL)
 368                 return 0;
 369         spin_lock_irqsave(&vga_lock, flags);
 370         vgadev = vgadev_find(pdev);
 371         if (vgadev == NULL) {
 372                 rc = -ENODEV;
 373                 goto bail;
 374         }
 375         if (__vga_tryget(vgadev, rsrc))
 376                 rc = -EBUSY;
 377 bail:
 378         spin_unlock_irqrestore(&vga_lock, flags);
 379         return rc;
 380 }
 381 EXPORT_SYMBOL(vga_tryget);
 382
 383 void vga_put(struct pci_dev *pdev, unsigned int rsrc)
 384 {
 385         struct vga_device *vgadev;
 386         unsigned long flags;
 387
 388         /* The one who calls us should check for this, but lets be sure... */
 389         if (pdev == NULL)
 390                 pdev = vga_default_device();
 391         if (pdev == NULL)
 392                 return;
 393         spin_lock_irqsave(&vga_lock, flags);
 394         vgadev = vgadev_find(pdev);
 395         if (vgadev == NULL)
 396                 goto bail;
 397         __vga_put(vgadev, rsrc);
 398 bail:
 399         spin_unlock_irqrestore(&vga_lock, flags);
 400 }
 401 EXPORT_SYMBOL(vga_put);
 402
 403 /*
 404  * Currently, we assume that the "initial" setup of the system is
 405  * not sane, that is we come up with conflicting devices and let
 406  * the arbiter's client decides if devices decodes or not legacy
 407  * things.
 408  */
 409 static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 410 {
 411         struct vga_device *vgadev;
 412         unsigned long flags;
 413         struct pci_bus *bus;
 414         struct pci_dev *bridge;
 415         u16 cmd;
 416
 417         /* Only deal with VGA class devices */
 418         if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
 419                 return false;
 420
 421         /* Allocate structure */
 422         vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
 423         if (vgadev == NULL) {
 424                 pr_err("vgaarb: failed to allocate pci device\n");
 425                 /* What to do on allocation failure ? For now, let's
 426                  * just do nothing, I'm not sure there is anything saner
 427                  * to be done
 428                  */
 429                 return false;
 430         }
 431
 432         memset(vgadev, 0, sizeof(*vgadev));
 433
 434         /* Take lock & check for duplicates */
 435         spin_lock_irqsave(&vga_lock, flags);
 436         if (vgadev_find(pdev) != NULL) {
 437                 BUG_ON(1);
 438                 goto fail;
 439         }
 440         vgadev->pdev = pdev;
 441
 442         /* By default, assume we decode everything */
 443         vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
 444                           VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 445
 446         /* by default mark it as decoding */
 447         vga_decode_count++;
 448         /* Mark that we "own" resources based on our enables, we will
 449          * clear that below if the bridge isn't forwarding
 450          */
 451         pci_read_config_word(pdev, PCI_COMMAND, &cmd);
 452         if (cmd & PCI_COMMAND_IO)
 453                 vgadev->owns |= VGA_RSRC_LEGACY_IO;
 454         if (cmd & PCI_COMMAND_MEMORY)
 455                 vgadev->owns |= VGA_RSRC_LEGACY_MEM;
 456
 457         /* Check if VGA cycles can get down to us */
 458         bus = pdev->bus;
 459         while (bus) {
 460                 bridge = bus->self;
 461                 if (bridge) {
 462                         u16 l;
 463                         pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
 464                                              &l);
 465                         if (!(l & PCI_BRIDGE_CTL_VGA)) {
 466                                 vgadev->owns = 0;
 467                                 break;
 468                         }
 469                 }
 470                 bus = bus->parent;
 471         }
 472
 473         /* Deal with VGA default device. Use first enabled one
 474          * by default if arch doesn't have it's own hook
 475          */
 476 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 477         if (vga_default == NULL &&
 478             ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
 479                 vga_default = pci_dev_get(pdev);
 480 #endif
 481
 482         /* Add to the list */
 483         list_add(&vgadev->list, &vga_list);
 484         vga_count++;
 485         pr_info("vgaarb: device added: PCI:%s,decodes=%s,owns=%s,locks=%s\n",
 486                 pci_name(pdev),
 487                 vga_iostate_to_str(vgadev->decodes),
 488                 vga_iostate_to_str(vgadev->owns),
 489                 vga_iostate_to_str(vgadev->locks));
 490
 491         spin_unlock_irqrestore(&vga_lock, flags);
 492         return true;
 493 fail:
 494         spin_unlock_irqrestore(&vga_lock, flags);
 495         kfree(vgadev);
 496         return false;
 497 }
 498
 499 static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
 500 {
 501         struct vga_device *vgadev;
 502         unsigned long flags;
 503         bool ret = true;
 504
 505         spin_lock_irqsave(&vga_lock, flags);
 506         vgadev = vgadev_find(pdev);
 507         if (vgadev == NULL) {
 508                 ret = false;
 509                 goto bail;
 510         }
 511
 512         if (vga_default == pdev) {
 513                 pci_dev_put(vga_default);
 514                 vga_default = NULL;
 515         }
 516
 517         if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
 518                 vga_decode_count--;
 519
 520         /* Remove entry from list */
 521         list_del(&vgadev->list);
 522         vga_count--;
 523         /* Notify userland driver that the device is gone so it discards
 524          * it's copies of the pci_dev pointer
 525          */
 526         vga_arb_device_card_gone(pdev);
 527
 528         /* Wake up all possible waiters */
 529         wake_up_all(&vga_wait_queue);
 530 bail:
 531         spin_unlock_irqrestore(&vga_lock, flags);
 532         kfree(vgadev);
 533         return ret;
 534 }
 535
 536 /* this is called with the lock */
 537 static inline void vga_update_device_decodes(struct vga_device *vgadev,
 538                                              int new_decodes)
 539 {
 540         int old_decodes;
 541         struct vga_device *new_vgadev, *conflict;
 542
 543         old_decodes = vgadev->decodes;
 544         vgadev->decodes = new_decodes;
 545
 546         pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
 547                 pci_name(vgadev->pdev),
 548                 vga_iostate_to_str(old_decodes),
 549                 vga_iostate_to_str(vgadev->decodes),
 550                 vga_iostate_to_str(vgadev->owns));
 551
 552
 553         /* if we own the decodes we should move them along to
 554            another card */
 555         if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
 556                 /* set us to own nothing */
 557                 vgadev->owns &= ~old_decodes;
 558                 list_for_each_entry(new_vgadev, &vga_list, list) {
 559                         if ((new_vgadev != vgadev) &&
 560                             (new_vgadev->decodes & VGA_RSRC_LEGACY_MASK)) {
 561                                 pr_info("vgaarb: transferring owner from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev), pci_name(new_vgadev->pdev));
 562                                 conflict = __vga_tryget(new_vgadev, VGA_RSRC_LEGACY_MASK);
 563                                 if (!conflict)
 564                                         __vga_put(new_vgadev, VGA_RSRC_LEGACY_MASK);
 565                                 break;
 566                         }
 567                 }
 568         }
 569
 570         /* change decodes counter */
 571         if (old_decodes != new_decodes) {
 572                 if (new_decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
 573                         vga_decode_count++;
 574                 else
 575                         vga_decode_count--;
 576         }
 577 }
 578
 579 void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes, bool userspace)
 580 {
 581         struct vga_device *vgadev;
 582         unsigned long flags;
 583
 584         decodes &= VGA_RSRC_LEGACY_MASK;
 585
 586         spin_lock_irqsave(&vga_lock, flags);
 587         vgadev = vgadev_find(pdev);
 588         if (vgadev == NULL)
 589                 goto bail;
 590
 591         /* don't let userspace futz with kernel driver decodes */
 592         if (userspace && vgadev->set_vga_decode)
 593                 goto bail;
 594
 595         /* update the device decodes + counter */
 596         vga_update_device_decodes(vgadev, decodes);
 597
 598         /* XXX if somebody is going from "doesn't decode" to "decodes" state
 599          * here, additional care must be taken as we may have pending owner
 600          * ship of non-legacy region ...
 601          */
 602 bail:
 603         spin_unlock_irqrestore(&vga_lock, flags);
 604 }
 605
 606 void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
 607 {
 608         __vga_set_legacy_decoding(pdev, decodes, false);
 609 }
 610 EXPORT_SYMBOL(vga_set_legacy_decoding);
 611
 612 /* call with NULL to unregister */
 613 int vga_client_register(struct pci_dev *pdev, void *cookie,
 614                         void (*irq_set_state)(void *cookie, bool state),
 615                         unsigned int (*set_vga_decode)(void *cookie, bool decode))
 616 {
 617         int ret = -1;
 618         struct vga_device *vgadev;
 619         unsigned long flags;
 620
 621         spin_lock_irqsave(&vga_lock, flags);
 622         vgadev = vgadev_find(pdev);
 623         if (!vgadev)
 624                 goto bail;
 625
 626         vgadev->irq_set_state = irq_set_state;
 627         vgadev->set_vga_decode = set_vga_decode;
 628         vgadev->cookie = cookie;
 629         ret = 0;
 630
 631 bail:
 632         spin_unlock_irqrestore(&vga_lock, flags);
 633         return ret;
 634
 635 }
 636 EXPORT_SYMBOL(vga_client_register);
 637
 638 /*
 639  * Char driver implementation
 640  *
 641  * Semantics is:
 642  *
 643  *  open       : open user instance of the arbitrer. by default, it's
 644  *                attached to the default VGA device of the system.
 645  *
 646  *  close      : close user instance, release locks
 647  *
 648  *  read       : return a string indicating the status of the target.
 649  *                an IO state string is of the form {io,mem,io+mem,none},
 650  *                mc and ic are respectively mem and io lock counts (for
 651  *                debugging/diagnostic only). "decodes" indicate what the
 652  *                card currently decodes, "owns" indicates what is currently
 653  *                enabled on it, and "locks" indicates what is locked by this
 654  *                card. If the card is unplugged, we get "invalid" then for
 655  *                card_ID and an -ENODEV error is returned for any command
 656  *                until a new card is targeted
 657  *
 658  *   "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
 659  *
 660  * write       : write a command to the arbiter. List of commands is:
 661  *
 662  *   target <card_ID>   : switch target to card <card_ID> (see below)
 663  *   lock <io_state>    : acquires locks on target ("none" is invalid io_state)
 664  *   trylock <io_state> : non-blocking acquire locks on target
 665  *   unlock <io_state>  : release locks on target
 666  *   unlock all         : release all locks on target held by this user
 667  *   decodes <io_state> : set the legacy decoding attributes for the card
 668  *
 669  * poll         : event if something change on any card (not just the target)
 670  *
 671  * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
 672  * to go back to the system default card (TODO: not implemented yet).
 673  * Currently, only PCI is supported as a prefix, but the userland API may
 674  * support other bus types in the future, even if the current kernel
 675  * implementation doesn't.
 676  *
 677  * Note about locks:
 678  *
 679  * The driver keeps track of which user has what locks on which card. It
 680  * supports stacking, like the kernel one. This complexifies the implementation
 681  * a bit, but makes the arbiter more tolerant to userspace problems and able
 682  * to properly cleanup in all cases when a process dies.
 683  * Currently, a max of 16 cards simultaneously can have locks issued from
 684  * userspace for a given user (file descriptor instance) of the arbiter.
 685  *
 686  * If the device is hot-unplugged, there is a hook inside the module to notify
 687  * they being added/removed in the system and automatically added/removed in
 688  * the arbiter.
 689  */
 690
 691 #define MAX_USER_CARDS         16
 692 #define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
 693
 694 /*
 695  * Each user has an array of these, tracking which cards have locks
 696  */
 697 struct vga_arb_user_card {
 698         struct pci_dev *pdev;
 699         unsigned int mem_cnt;
 700         unsigned int io_cnt;
 701 };
 702
 703 struct vga_arb_private {
 704         struct list_head list;
 705         struct pci_dev *target;
 706         struct vga_arb_user_card cards[MAX_USER_CARDS];
 707         spinlock_t lock;
 708 };
 709
 710 static LIST_HEAD(vga_user_list);
 711 static DEFINE_SPINLOCK(vga_user_lock);
 712
 713
 714 /*
 715  * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
 716  * returns the respective values. If the string is not in this format,
 717  * it returns 0.
 718  */
 719 static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
 720                                unsigned int *bus, unsigned int *devfn)
 721 {
 722         int n;
 723         unsigned int slot, func;
 724
 725
 726         n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
 727         if (n != 4)
 728                 return 0;
 729
 730         *devfn = PCI_DEVFN(slot, func);
 731
 732         return 1;
 733 }
 734
 735 static ssize_t vga_arb_read(struct file *file, char __user * buf,
 736                             size_t count, loff_t *ppos)
 737 {
 738         struct vga_arb_private *priv = file->private_data;
 739         struct vga_device *vgadev;
 740         struct pci_dev *pdev;
 741         unsigned long flags;
 742         size_t len;
 743         int rc;
 744         char *lbuf;
 745
 746         lbuf = kmalloc(1024, GFP_KERNEL);
 747         if (lbuf == NULL)
 748                 return -ENOMEM;
 749
 750         /* Shields against vga_arb_device_card_gone (pci_dev going
 751          * away), and allows access to vga list
 752          */
 753         spin_lock_irqsave(&vga_lock, flags);
 754
 755         /* If we are targetting the default, use it */
 756         pdev = priv->target;
 757         if (pdev == NULL || pdev == PCI_INVALID_CARD) {
 758                 spin_unlock_irqrestore(&vga_lock, flags);
 759                 len = sprintf(lbuf, "invalid");
 760                 goto done;
 761         }
 762
 763         /* Find card vgadev structure */
 764         vgadev = vgadev_find(pdev);
 765         if (vgadev == NULL) {
 766                 /* Wow, it's not in the list, that shouldn't happen,
 767                  * let's fix us up and return invalid card
 768                  */
 769                 if (pdev == priv->target)
 770                         vga_arb_device_card_gone(pdev);
 771                 spin_unlock_irqrestore(&vga_lock, flags);
 772                 len = sprintf(lbuf, "invalid");
 773                 goto done;
 774         }
 775
 776         /* Fill the buffer with infos */
 777         len = snprintf(lbuf, 1024,
 778                        "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
 779                        vga_decode_count, pci_name(pdev),
 780                        vga_iostate_to_str(vgadev->decodes),
 781                        vga_iostate_to_str(vgadev->owns),
 782                        vga_iostate_to_str(vgadev->locks),
 783                        vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
 784
 785         spin_unlock_irqrestore(&vga_lock, flags);
 786 done:
 787
 788         /* Copy that to user */
 789         if (len > count)
 790                 len = count;
 791         rc = copy_to_user(buf, lbuf, len);
 792         kfree(lbuf);
 793         if (rc)
 794                 return -EFAULT;
 795         return len;
 796 }
 797
 798 /*
 799  * TODO: To avoid parsing inside kernel and to improve the speed we may
 800  * consider use ioctl here
 801  */
 802 static ssize_t vga_arb_write(struct file *file, const char __user * buf,
 803                              size_t count, loff_t *ppos)
 804 {
 805         struct vga_arb_private *priv = file->private_data;
 806         struct vga_arb_user_card *uc = NULL;
 807         struct pci_dev *pdev;
 808
 809         unsigned int io_state;
 810
 811         char *kbuf, *curr_pos;
 812         size_t remaining = count;
 813
 814         int ret_val;
 815         int i;
 816
 817
 818         kbuf = kmalloc(count + 1, GFP_KERNEL);
 819         if (!kbuf)
 820                 return -ENOMEM;
 821
 822         if (copy_from_user(kbuf, buf, count)) {
 823                 kfree(kbuf);
 824                 return -EFAULT;
 825         }
 826         curr_pos = kbuf;
 827         kbuf[count] = '\0';     /* Just to make sure... */
 828
 829         if (strncmp(curr_pos, "lock ", 5) == 0) {
 830                 curr_pos += 5;
 831                 remaining -= 5;
 832
 833                 pr_devel("client 0x%p called 'lock'\n", priv);
 834
 835                 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
 836                         ret_val = -EPROTO;
 837                         goto done;
 838                 }
 839                 if (io_state == VGA_RSRC_NONE) {
 840                         ret_val = -EPROTO;
 841                         goto done;
 842                 }
 843
 844                 pdev = priv->target;
 845                 if (priv->target == NULL) {
 846                         ret_val = -ENODEV;
 847                         goto done;
 848                 }
 849
 850                 vga_get_uninterruptible(pdev, io_state);
 851
 852                 /* Update the client's locks lists... */
 853                 for (i = 0; i < MAX_USER_CARDS; i++) {
 854                         if (priv->cards[i].pdev == pdev) {
 855                                 if (io_state & VGA_RSRC_LEGACY_IO)
 856                                         priv->cards[i].io_cnt++;
 857                                 if (io_state & VGA_RSRC_LEGACY_MEM)
 858                                         priv->cards[i].mem_cnt++;
 859                                 break;
 860                         }
 861                 }
 862
 863                 ret_val = count;
 864                 goto done;
 865         } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
 866                 curr_pos += 7;
 867                 remaining -= 7;
 868
 869                 pr_devel("client 0x%p called 'unlock'\n", priv);
 870
 871                 if (strncmp(curr_pos, "all", 3) == 0)
 872                         io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
 873                 else {
 874                         if (!vga_str_to_iostate
 875                             (curr_pos, remaining, &io_state)) {
 876                                 ret_val = -EPROTO;
 877                                 goto done;
 878                         }
 879                         /* TODO: Add this?
 880                            if (io_state == VGA_RSRC_NONE) {
 881                            ret_val = -EPROTO;
 882                            goto done;
 883                            }
 884                           */
 885                 }
 886
 887                 pdev = priv->target;
 888                 if (priv->target == NULL) {
 889                         ret_val = -ENODEV;
 890                         goto done;
 891                 }
 892                 for (i = 0; i < MAX_USER_CARDS; i++) {
 893                         if (priv->cards[i].pdev == pdev)
 894                                 uc = &priv->cards[i];
 895                 }
 896
 897                 if (!uc)
 898                         return -EINVAL;
 899
 900                 if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0)
 901                         return -EINVAL;
 902
 903                 if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0)
 904                         return -EINVAL;
 905
 906                 vga_put(pdev, io_state);
 907
 908                 if (io_state & VGA_RSRC_LEGACY_IO)
 909                         uc->io_cnt--;
 910                 if (io_state & VGA_RSRC_LEGACY_MEM)
 911                         uc->mem_cnt--;
 912
 913                 ret_val = count;
 914                 goto done;
 915         } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
 916                 curr_pos += 8;
 917                 remaining -= 8;
 918
 919                 pr_devel("client 0x%p called 'trylock'\n", priv);
 920
 921                 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
 922                         ret_val = -EPROTO;
 923                         goto done;
 924                 }
 925                 /* TODO: Add this?
 926                    if (io_state == VGA_RSRC_NONE) {
 927                    ret_val = -EPROTO;
 928                    goto done;
 929                    }
 930                  */
 931
 932                 pdev = priv->target;
 933                 if (priv->target == NULL) {
 934                         ret_val = -ENODEV;
 935                         goto done;
 936                 }
 937
 938                 if (vga_tryget(pdev, io_state)) {
 939                         /* Update the client's locks lists... */
 940                         for (i = 0; i < MAX_USER_CARDS; i++) {
 941                                 if (priv->cards[i].pdev == pdev) {
 942                                         if (io_state & VGA_RSRC_LEGACY_IO)
 943                                                 priv->cards[i].io_cnt++;
 944                                         if (io_state & VGA_RSRC_LEGACY_MEM)
 945                                                 priv->cards[i].mem_cnt++;
 946                                         break;
 947                                 }
 948                         }
 949                         ret_val = count;
 950                         goto done;
 951                 } else {
 952                         ret_val = -EBUSY;
 953                         goto done;
 954                 }
 955
 956         } else if (strncmp(curr_pos, "target ", 7) == 0) {
 957                 unsigned int domain, bus, devfn;
 958                 struct vga_device *vgadev;
 959
 960                 curr_pos += 7;
 961                 remaining -= 7;
 962                 pr_devel("client 0x%p called 'target'\n", priv);
 963                 /* if target is default */
 964                 if (!strncmp(curr_pos, "default", 7))
 965                         pdev = pci_dev_get(vga_default_device());
 966                 else {
 967                         if (!vga_pci_str_to_vars(curr_pos, remaining,
 968                                                  &domain, &bus, &devfn)) {
 969                                 ret_val = -EPROTO;
 970                                 goto done;
 971                         }
 972
 973                         pdev = pci_get_bus_and_slot(bus, devfn);
 974                         if (!pdev) {
 975                                 pr_info("vgaarb: invalid PCI address!\n");
 976                                 ret_val = -ENODEV;
 977                                 goto done;
 978                         }
 979                 }
 980
 981                 vgadev = vgadev_find(pdev);
 982                 if (vgadev == NULL) {
 983                         pr_info("vgaarb: this pci device is not a vga device\n");
 984                         pci_dev_put(pdev);
 985                         ret_val = -ENODEV;
 986                         goto done;
 987                 }
 988
 989                 priv->target = pdev;
 990                 for (i = 0; i < MAX_USER_CARDS; i++) {
 991                         if (priv->cards[i].pdev == pdev)
 992                                 break;
 993                         if (priv->cards[i].pdev == NULL) {
 994                                 priv->cards[i].pdev = pdev;
 995                                 priv->cards[i].io_cnt = 0;
 996                                 priv->cards[i].mem_cnt = 0;
 997                                 break;
 998                         }
 999                 }
1000                 if (i == MAX_USER_CARDS) {
1001                         pr_err("vgaarb: maximum user cards number reached!\n");
1002                         pci_dev_put(pdev);
1003                         /* XXX: which value to return? */
1004                         ret_val =  -ENOMEM;
1005                         goto done;
1006                 }
1007
1008                 ret_val = count;
1009                 pci_dev_put(pdev);
1010                 goto done;
1011
1012
1013         } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
1014                 curr_pos += 8;
1015                 remaining -= 8;
1016                 pr_devel("vgaarb: client 0x%p called 'decodes'\n", priv);
1017
1018                 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1019                         ret_val = -EPROTO;
1020                         goto done;
1021                 }
1022                 pdev = priv->target;
1023                 if (priv->target == NULL) {
1024                         ret_val = -ENODEV;
1025                         goto done;
1026                 }
1027
1028                 __vga_set_legacy_decoding(pdev, io_state, true);
1029                 ret_val = count;
1030                 goto done;
1031         }
1032         /* If we got here, the message written is not part of the protocol! */
1033         kfree(kbuf);
1034         return -EPROTO;
1035
1036 done:
1037         kfree(kbuf);
1038         return ret_val;
1039 }
1040
1041 static unsigned int vga_arb_fpoll(struct file *file, poll_table * wait)
1042 {
1043         struct vga_arb_private *priv = file->private_data;
1044
1045         pr_devel("%s\n", __func__);
1046
1047         if (priv == NULL)
1048                 return -ENODEV;
1049         poll_wait(file, &vga_wait_queue, wait);
1050         return POLLIN;
1051 }
1052
1053 static int vga_arb_open(struct inode *inode, struct file *file)
1054 {
1055         struct vga_arb_private *priv;
1056         unsigned long flags;
1057
1058         pr_devel("%s\n", __func__);
1059
1060         priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
1061         if (priv == NULL)
1062                 return -ENOMEM;
1063         memset(priv, 0, sizeof(*priv));
1064         spin_lock_init(&priv->lock);
1065         file->private_data = priv;
1066
1067         spin_lock_irqsave(&vga_user_lock, flags);
1068         list_add(&priv->list, &vga_user_list);
1069         spin_unlock_irqrestore(&vga_user_lock, flags);
1070
1071         /* Set the client' lists of locks */
1072         priv->target = vga_default_device(); /* Maybe this is still null! */
1073         priv->cards[0].pdev = priv->target;
1074         priv->cards[0].io_cnt = 0;
1075         priv->cards[0].mem_cnt = 0;
1076
1077
1078         return 0;
1079 }
1080
1081 static int vga_arb_release(struct inode *inode, struct file *file)
1082 {
1083         struct vga_arb_private *priv = file->private_data;
1084         struct vga_arb_user_card *uc;
1085         unsigned long flags;
1086         int i;
1087
1088         pr_devel("%s\n", __func__);
1089
1090         if (priv == NULL)
1091                 return -ENODEV;
1092
1093         spin_lock_irqsave(&vga_user_lock, flags);
1094         list_del(&priv->list);
1095         for (i = 0; i < MAX_USER_CARDS; i++) {
1096                 uc = &priv->cards[i];
1097                 if (uc->pdev == NULL)
1098                         continue;
1099                 pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
1100                          uc->io_cnt, uc->mem_cnt);
1101                 while (uc->io_cnt--)
1102                         vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
1103                 while (uc->mem_cnt--)
1104                         vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
1105         }
1106         spin_unlock_irqrestore(&vga_user_lock, flags);
1107
1108         kfree(priv);
1109
1110         return 0;
1111 }
1112
1113 static void vga_arb_device_card_gone(struct pci_dev *pdev)
1114 {
1115 }
1116
1117 /*
1118  * callback any registered clients to let them know we have a
1119  * change in VGA cards
1120  */
1121 static void vga_arbiter_notify_clients(void)
1122 {
1123         struct vga_device *vgadev;
1124         unsigned long flags;
1125         uint32_t new_decodes;
1126         bool new_state;
1127
1128         if (!vga_arbiter_used)
1129                 return;
1130
1131         spin_lock_irqsave(&vga_lock, flags);
1132         list_for_each_entry(vgadev, &vga_list, list) {
1133                 if (vga_count > 1)
1134                         new_state = false;
1135                 else
1136                         new_state = true;
1137                 if (vgadev->set_vga_decode) {
1138                         new_decodes = vgadev->set_vga_decode(vgadev->cookie, new_state);
1139                         vga_update_device_decodes(vgadev, new_decodes);
1140                 }
1141         }
1142         spin_unlock_irqrestore(&vga_lock, flags);
1143 }
1144
1145 static int pci_notify(struct notifier_block *nb, unsigned long action,
1146                       void *data)
1147 {
1148         struct device *dev = data;
1149         struct pci_dev *pdev = to_pci_dev(dev);
1150         bool notify = false;
1151
1152         pr_devel("%s\n", __func__);
1153
1154         /* For now we're only intereted in devices added and removed. I didn't
1155          * test this thing here, so someone needs to double check for the
1156          * cases of hotplugable vga cards. */
1157         if (action == BUS_NOTIFY_ADD_DEVICE)
1158                 notify = vga_arbiter_add_pci_device(pdev);
1159         else if (action == BUS_NOTIFY_DEL_DEVICE)
1160                 notify = vga_arbiter_del_pci_device(pdev);
1161
1162         if (notify)
1163                 vga_arbiter_notify_clients();
1164         return 0;
1165 }
1166
1167 static struct notifier_block pci_notifier = {
1168         .notifier_call = pci_notify,
1169 };
1170
1171 static const struct file_operations vga_arb_device_fops = {
1172         .read = vga_arb_read,
1173         .write = vga_arb_write,
1174         .poll = vga_arb_fpoll,
1175         .open = vga_arb_open,
1176         .release = vga_arb_release,
1177 };
1178
1179 static struct miscdevice vga_arb_device = {
1180         MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
1181 };
1182
1183 static int __init vga_arb_device_init(void)
1184 {
1185         int rc;
1186         struct pci_dev *pdev;
1187
1188         rc = misc_register(&vga_arb_device);
1189         if (rc < 0)
1190                 pr_err("vgaarb: error %d registering device\n", rc);
1191
1192         bus_register_notifier(&pci_bus_type, &pci_notifier);
1193
1194         /* We add all pci devices satisfying vga class in the arbiter by
1195          * default */
1196         pdev = NULL;
1197         while ((pdev =
1198                 pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
1199                                PCI_ANY_ID, pdev)) != NULL)
1200                 vga_arbiter_add_pci_device(pdev);
1201
1202         pr_info("vgaarb: loaded\n");
1203         return rc;
1204 }
1205 subsys_initcall(vga_arb_device_init);