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 #include <linux/slab.h>
  24
  25 #include <linux/uaccess.h>
  26
  27 #include <linux/vgaarb.h>
  28
  29 static void vga_arbiter_notify_clients(void);
  30 /*
  31  * We keep a list of all vga devices in the system to speed
  32  * up the various operations of the arbiter
  33  */
  34 struct vga_device {
  35         struct list_head list;
  36         struct pci_dev *pdev;
  37         unsigned int decodes;   /* what does it decodes */
  38         unsigned int owns;      /* what does it owns */
  39         unsigned int locks;     /* what does it locks */
  40         unsigned int io_lock_cnt;       /* legacy IO lock count */
  41         unsigned int mem_lock_cnt;      /* legacy MEM lock count */
  42         unsigned int io_norm_cnt;       /* normal IO count */
  43         unsigned int mem_norm_cnt;      /* normal MEM count */
  44
  45         /* allow IRQ enable/disable hook */
  46         void *cookie;
  47         void (*irq_set_state)(void *cookie, bool enable);
  48         unsigned int (*set_vga_decode)(void *cookie, bool decode);
  49 };
  50
  51 static LIST_HEAD(vga_list);
  52 static int vga_count, vga_decode_count;
  53 static bool vga_arbiter_used;
  54 static DEFINE_SPINLOCK(vga_lock);
  55 static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
  56
  57
  58 static const char *vga_iostate_to_str(unsigned int iostate)
  59 {
  60         /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
  61         iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
  62         switch (iostate) {
  63         case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
  64                 return "io+mem";
  65         case VGA_RSRC_LEGACY_IO:
  66                 return "io";
  67         case VGA_RSRC_LEGACY_MEM:
  68                 return "mem";
  69         }
  70         return "none";
  71 }
  72
  73 static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
  74 {
  75         /* we could in theory hand out locks on IO and mem
  76          * separately to userspace but it can cause deadlocks */
  77         if (strncmp(buf, "none", 4) == 0) {
  78                 *io_state = VGA_RSRC_NONE;
  79                 return 1;
  80         }
  81
  82         /* XXX We're not chekcing the str_size! */
  83         if (strncmp(buf, "io+mem", 6) == 0)
  84                 goto both;
  85         else if (strncmp(buf, "io", 2) == 0)
  86                 goto both;
  87         else if (strncmp(buf, "mem", 3) == 0)
  88                 goto both;
  89         return 0;
  90 both:
  91         *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
  92         return 1;
  93 }
  94
  95 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
  96 /* this is only used a cookie - it should not be dereferenced */
  97 static struct pci_dev *vga_default;
  98 #endif
  99
 100 static void vga_arb_device_card_gone(struct pci_dev *pdev);
 101
 102 /* Find somebody in our list */
 103 static struct vga_device *vgadev_find(struct pci_dev *pdev)
 104 {
 105         struct vga_device *vgadev;
 106
 107         list_for_each_entry(vgadev, &vga_list, list)
 108                 if (pdev == vgadev->pdev)
 109                         return vgadev;
 110         return NULL;
 111 }
 112
 113 /* Returns the default VGA device (vgacon's babe) */
 114 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 115 struct pci_dev *vga_default_device(void)
 116 {
 117         return vga_default;
 118 }
 119 #endif
 120
 121 static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
 122 {
 123         if (vgadev->irq_set_state)
 124                 vgadev->irq_set_state(vgadev->cookie, state);
 125 }
 126
 127
 128 /* If we don't ever use VGA arb we should avoid
 129    turning off anything anywhere due to old X servers getting
 130    confused about the boot device not being VGA */
 131 static void vga_check_first_use(void)
 132 {
 133         /* we should inform all GPUs in the system that
 134          * VGA arb has occured and to try and disable resources
 135          * if they can */
 136         if (!vga_arbiter_used) {
 137                 vga_arbiter_used = true;
 138                 vga_arbiter_notify_clients();
 139         }
 140 }
 141
 142 static struct vga_device *__vga_tryget(struct vga_device *vgadev,
 143                                        unsigned int rsrc)
 144 {
 145         unsigned int wants, legacy_wants, match;
 146         struct vga_device *conflict;
 147         unsigned int pci_bits;
 148         /* Account for "normal" resources to lock. If we decode the legacy,
 149          * counterpart, we need to request it as well
 150          */
 151         if ((rsrc & VGA_RSRC_NORMAL_IO) &&
 152             (vgadev->decodes & VGA_RSRC_LEGACY_IO))
 153                 rsrc |= VGA_RSRC_LEGACY_IO;
 154         if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
 155             (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
 156                 rsrc |= VGA_RSRC_LEGACY_MEM;
 157
 158         pr_devel("%s: %d\n", __func__, rsrc);
 159         pr_devel("%s: owns: %d\n", __func__, vgadev->owns);
 160
 161         /* Check what resources we need to acquire */
 162         wants = rsrc & ~vgadev->owns;
 163
 164         /* We already own everything, just mark locked & bye bye */
 165         if (wants == 0)
 166                 goto lock_them;
 167
 168         /* We don't need to request a legacy resource, we just enable
 169          * appropriate decoding and go
 170          */
 171         legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
 172         if (legacy_wants == 0)
 173                 goto enable_them;
 174
 175         /* Ok, we don't, let's find out how we need to kick off */
 176         list_for_each_entry(conflict, &vga_list, list) {
 177                 unsigned int lwants = legacy_wants;
 178                 unsigned int change_bridge = 0;
 179
 180                 /* Don't conflict with myself */
 181                 if (vgadev == conflict)
 182                         continue;
 183
 184                 /* Check if the architecture allows a conflict between those
 185                  * 2 devices or if they are on separate domains
 186                  */
 187                 if (!vga_conflicts(vgadev->pdev, conflict->pdev))
 188                         continue;
 189
 190                 /* We have a possible conflict. before we go further, we must
 191                  * check if we sit on the same bus as the conflicting device.
 192                  * if we don't, then we must tie both IO and MEM resources
 193                  * together since there is only a single bit controlling
 194                  * VGA forwarding on P2P bridges
 195                  */
 196                 if (vgadev->pdev->bus != conflict->pdev->bus) {
 197                         change_bridge = 1;
 198                         lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
 199                 }
 200
 201                 /* Check if the guy has a lock on the resource. If he does,
 202                  * return the conflicting entry
 203                  */
 204                 if (conflict->locks & lwants)
 205                         return conflict;
 206
 207                 /* Ok, now check if he owns the resource we want. We don't need
 208                  * to check "decodes" since it should be impossible to own
 209                  * own legacy resources you don't decode unless I have a bug
 210                  * in this code...
 211                  */
 212                 WARN_ON(conflict->owns & ~conflict->decodes);
 213                 match = lwants & conflict->owns;
 214                 if (!match)
 215                         continue;
 216
 217                 /* looks like he doesn't have a lock, we can steal
 218                  * them from him
 219                  */
 220                 vga_irq_set_state(conflict, false);
 221
 222                 pci_bits = 0;
 223                 if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
 224                         pci_bits |= PCI_COMMAND_MEMORY;
 225                 if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
 226                         pci_bits |= PCI_COMMAND_IO;
 227
 228                 pci_set_vga_state(conflict->pdev, false, pci_bits,
 229                                   change_bridge);
 230                 conflict->owns &= ~lwants;
 231                 /* If he also owned non-legacy, that is no longer the case */
 232                 if (lwants & VGA_RSRC_LEGACY_MEM)
 233                         conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
 234                 if (lwants & VGA_RSRC_LEGACY_IO)
 235                         conflict->owns &= ~VGA_RSRC_NORMAL_IO;
 236         }
 237
 238 enable_them:
 239         /* ok dude, we got it, everybody conflicting has been disabled, let's
 240          * enable us. Make sure we don't mark a bit in "owns" that we don't
 241          * also have in "decodes". We can lock resources we don't decode but
 242          * not own them.
 243          */
 244         pci_bits = 0;
 245         if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
 246                 pci_bits |= PCI_COMMAND_MEMORY;
 247         if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
 248                 pci_bits |= PCI_COMMAND_IO;
 249         pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
 250
 251         vga_irq_set_state(vgadev, true);
 252         vgadev->owns |= (wants & vgadev->decodes);
 253 lock_them:
 254         vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
 255         if (rsrc & VGA_RSRC_LEGACY_IO)
 256                 vgadev->io_lock_cnt++;
 257         if (rsrc & VGA_RSRC_LEGACY_MEM)
 258                 vgadev->mem_lock_cnt++;
 259         if (rsrc & VGA_RSRC_NORMAL_IO)
 260                 vgadev->io_norm_cnt++;
 261         if (rsrc & VGA_RSRC_NORMAL_MEM)
 262                 vgadev->mem_norm_cnt++;
 263
 264         return NULL;
 265 }
 266
 267 static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
 268 {
 269         unsigned int old_locks = vgadev->locks;
 270
 271         pr_devel("%s\n", __func__);
 272
 273         /* Update our counters, and account for equivalent legacy resources
 274          * if we decode them
 275          */
 276         if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
 277                 vgadev->io_norm_cnt--;
 278                 if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
 279                         rsrc |= VGA_RSRC_LEGACY_IO;
 280         }
 281         if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
 282                 vgadev->mem_norm_cnt--;
 283                 if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
 284                         rsrc |= VGA_RSRC_LEGACY_MEM;
 285         }
 286         if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
 287                 vgadev->io_lock_cnt--;
 288         if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
 289                 vgadev->mem_lock_cnt--;
 290
 291         /* Just clear lock bits, we do lazy operations so we don't really
 292          * have to bother about anything else at this point
 293          */
 294         if (vgadev->io_lock_cnt == 0)
 295                 vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
 296         if (vgadev->mem_lock_cnt == 0)
 297                 vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
 298
 299         /* Kick the wait queue in case somebody was waiting if we actually
 300          * released something
 301          */
 302         if (old_locks != vgadev->locks)
 303                 wake_up_all(&vga_wait_queue);
 304 }
 305
 306 int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
 307 {
 308         struct vga_device *vgadev, *conflict;
 309         unsigned long flags;
 310         wait_queue_t wait;
 311         int rc = 0;
 312
 313         vga_check_first_use();
 314         /* The one who calls us should check for this, but lets be sure... */
 315         if (pdev == NULL)
 316                 pdev = vga_default_device();
 317         if (pdev == NULL)
 318                 return 0;
 319
 320         for (;;) {
 321                 spin_lock_irqsave(&vga_lock, flags);
 322                 vgadev = vgadev_find(pdev);
 323                 if (vgadev == NULL) {
 324                         spin_unlock_irqrestore(&vga_lock, flags);
 325                         rc = -ENODEV;
 326                         break;
 327                 }
 328                 conflict = __vga_tryget(vgadev, rsrc);
 329                 spin_unlock_irqrestore(&vga_lock, flags);
 330                 if (conflict == NULL)
 331                         break;
 332
 333
 334                 /* We have a conflict, we wait until somebody kicks the
 335                  * work queue. Currently we have one work queue that we
 336                  * kick each time some resources are released, but it would
 337                  * be fairly easy to have a per device one so that we only
 338                  * need to attach to the conflicting device
 339                  */
 340                 init_waitqueue_entry(&wait, current);
 341                 add_wait_queue(&vga_wait_queue, &wait);
 342                 set_current_state(interruptible ?
 343                                   TASK_INTERRUPTIBLE :
 344                                   TASK_UNINTERRUPTIBLE);
 345                 if (signal_pending(current)) {
 346                         rc = -EINTR;
 347                         break;
 348                 }
 349                 schedule();
 350                 remove_wait_queue(&vga_wait_queue, &wait);
 351                 set_current_state(TASK_RUNNING);
 352         }
 353         return rc;
 354 }
 355 EXPORT_SYMBOL(vga_get);
 356
 357 int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
 358 {
 359         struct vga_device *vgadev;
 360         unsigned long flags;
 361         int rc = 0;
 362
 363         vga_check_first_use();
 364
 365         /* The one who calls us should check for this, but lets be sure... */
 366         if (pdev == NULL)
 367                 pdev = vga_default_device();
 368         if (pdev == NULL)
 369                 return 0;
 370         spin_lock_irqsave(&vga_lock, flags);
 371         vgadev = vgadev_find(pdev);
 372         if (vgadev == NULL) {
 373                 rc = -ENODEV;
 374                 goto bail;
 375         }
 376         if (__vga_tryget(vgadev, rsrc))
 377                 rc = -EBUSY;
 378 bail:
 379         spin_unlock_irqrestore(&vga_lock, flags);
 380         return rc;
 381 }
 382 EXPORT_SYMBOL(vga_tryget);
 383
 384 void vga_put(struct pci_dev *pdev, unsigned int rsrc)
 385 {
 386         struct vga_device *vgadev;
 387         unsigned long flags;
 388
 389         /* The one who calls us should check for this, but lets be sure... */
 390         if (pdev == NULL)
 391                 pdev = vga_default_device();
 392         if (pdev == NULL)
 393                 return;
 394         spin_lock_irqsave(&vga_lock, flags);
 395         vgadev = vgadev_find(pdev);
 396         if (vgadev == NULL)
 397                 goto bail;
 398         __vga_put(vgadev, rsrc);
 399 bail:
 400         spin_unlock_irqrestore(&vga_lock, flags);
 401 }
 402 EXPORT_SYMBOL(vga_put);
 403
 404 /*
 405  * Currently, we assume that the "initial" setup of the system is
 406  * not sane, that is we come up with conflicting devices and let
 407  * the arbiter's client decides if devices decodes or not legacy
 408  * things.
 409  */
 410 static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 411 {
 412         struct vga_device *vgadev;
 413         unsigned long flags;
 414         struct pci_bus *bus;
 415         struct pci_dev *bridge;
 416         u16 cmd;
 417
 418         /* Only deal with VGA class devices */
 419         if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
 420                 return false;
 421
 422         /* Allocate structure */
 423         vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
 424         if (vgadev == NULL) {
 425                 pr_err("vgaarb: failed to allocate pci device\n");
 426                 /* What to do on allocation failure ? For now, let's
 427                  * just do nothing, I'm not sure there is anything saner
 428                  * to be done
 429                  */
 430                 return false;
 431         }
 432
 433         memset(vgadev, 0, sizeof(*vgadev));
 434
 435         /* Take lock & check for duplicates */
 436         spin_lock_irqsave(&vga_lock, flags);
 437         if (vgadev_find(pdev) != NULL) {
 438                 BUG_ON(1);
 439                 goto fail;
 440         }
 441         vgadev->pdev = pdev;
 442
 443         /* By default, assume we decode everything */
 444         vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
 445                           VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 446
 447         /* by default mark it as decoding */
 448         vga_decode_count++;
 449         /* Mark that we "own" resources based on our enables, we will
 450          * clear that below if the bridge isn't forwarding
 451          */
 452         pci_read_config_word(pdev, PCI_COMMAND, &cmd);
 453         if (cmd & PCI_COMMAND_IO)
 454                 vgadev->owns |= VGA_RSRC_LEGACY_IO;
 455         if (cmd & PCI_COMMAND_MEMORY)
 456                 vgadev->owns |= VGA_RSRC_LEGACY_MEM;
 457
 458         /* Check if VGA cycles can get down to us */
 459         bus = pdev->bus;
 460         while (bus) {
 461                 bridge = bus->self;
 462                 if (bridge) {
 463                         u16 l;
 464                         pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
 465                                              &l);
 466                         if (!(l & PCI_BRIDGE_CTL_VGA)) {
 467                                 vgadev->owns = 0;
 468                                 break;
 469                         }
 470                 }
 471                 bus = bus->parent;
 472         }
 473
 474         /* Deal with VGA default device. Use first enabled one
 475          * by default if arch doesn't have it's own hook
 476          */
 477 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 478         if (vga_default == NULL &&
 479             ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
 480                 vga_default = pci_dev_get(pdev);
 481 #endif
 482
 483         /* Add to the list */
 484         list_add(&vgadev->list, &vga_list);
 485         vga_count++;
 486         pr_info("vgaarb: device added: PCI:%s,decodes=%s,owns=%s,locks=%s\n",
 487                 pci_name(pdev),
 488                 vga_iostate_to_str(vgadev->decodes),
 489                 vga_iostate_to_str(vgadev->owns),
 490                 vga_iostate_to_str(vgadev->locks));
 491
 492         spin_unlock_irqrestore(&vga_lock, flags);
 493         return true;
 494 fail:
 495         spin_unlock_irqrestore(&vga_lock, flags);
 496         kfree(vgadev);
 497         return false;
 498 }
 499
 500 static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
 501 {
 502         struct vga_device *vgadev;
 503         unsigned long flags;
 504         bool ret = true;
 505
 506         spin_lock_irqsave(&vga_lock, flags);
 507         vgadev = vgadev_find(pdev);
 508         if (vgadev == NULL) {
 509                 ret = false;
 510                 goto bail;
 511         }
 512
 513         if (vga_default == pdev) {
 514                 pci_dev_put(vga_default);
 515                 vga_default = NULL;
 516         }
 517
 518         if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
 519                 vga_decode_count--;
 520
 521         /* Remove entry from list */
 522         list_del(&vgadev->list);
 523         vga_count--;
 524         /* Notify userland driver that the device is gone so it discards
 525          * it's copies of the pci_dev pointer
 526          */
 527         vga_arb_device_card_gone(pdev);
 528
 529         /* Wake up all possible waiters */
 530         wake_up_all(&vga_wait_queue);
 531 bail:
 532         spin_unlock_irqrestore(&vga_lock, flags);
 533         kfree(vgadev);
 534         return ret;
 535 }
 536
 537 /* this is called with the lock */
 538 static inline void vga_update_device_decodes(struct vga_device *vgadev,
 539                                              int new_decodes)
 540 {
 541         int old_decodes;
 542         struct vga_device *new_vgadev, *conflict;
 543
 544         old_decodes = vgadev->decodes;
 545         vgadev->decodes = new_decodes;
 546
 547         pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
 548                 pci_name(vgadev->pdev),
 549                 vga_iostate_to_str(old_decodes),
 550                 vga_iostate_to_str(vgadev->decodes),
 551                 vga_iostate_to_str(vgadev->owns));
 552
 553
 554         /* if we own the decodes we should move them along to
 555            another card */
 556         if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
 557                 /* set us to own nothing */
 558                 vgadev->owns &= ~old_decodes;
 559                 list_for_each_entry(new_vgadev, &vga_list, list) {
 560                         if ((new_vgadev != vgadev) &&
 561                             (new_vgadev->decodes & VGA_RSRC_LEGACY_MASK)) {
 562                                 pr_info("vgaarb: transferring owner from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev), pci_name(new_vgadev->pdev));
 563                                 conflict = __vga_tryget(new_vgadev, VGA_RSRC_LEGACY_MASK);
 564                                 if (!conflict)
 565                                         __vga_put(new_vgadev, VGA_RSRC_LEGACY_MASK);
 566                                 break;
 567                         }
 568                 }
 569         }
 570
 571         /* change decodes counter */
 572         if (old_decodes != new_decodes) {
 573                 if (new_decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
 574                         vga_decode_count++;
 575                 else
 576                         vga_decode_count--;
 577         }
 578 }
 579
 580 void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes, bool userspace)
 581 {
 582         struct vga_device *vgadev;
 583         unsigned long flags;
 584
 585         decodes &= VGA_RSRC_LEGACY_MASK;
 586
 587         spin_lock_irqsave(&vga_lock, flags);
 588         vgadev = vgadev_find(pdev);
 589         if (vgadev == NULL)
 590                 goto bail;
 591
 592         /* don't let userspace futz with kernel driver decodes */
 593         if (userspace && vgadev->set_vga_decode)
 594                 goto bail;
 595
 596         /* update the device decodes + counter */
 597         vga_update_device_decodes(vgadev, decodes);
 598
 599         /* XXX if somebody is going from "doesn't decode" to "decodes" state
 600          * here, additional care must be taken as we may have pending owner
 601          * ship of non-legacy region ...
 602          */
 603 bail:
 604         spin_unlock_irqrestore(&vga_lock, flags);
 605 }
 606
 607 void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
 608 {
 609         __vga_set_legacy_decoding(pdev, decodes, false);
 610 }
 611 EXPORT_SYMBOL(vga_set_legacy_decoding);
 612
 613 /* call with NULL to unregister */
 614 int vga_client_register(struct pci_dev *pdev, void *cookie,
 615                         void (*irq_set_state)(void *cookie, bool state),
 616                         unsigned int (*set_vga_decode)(void *cookie, bool decode))
 617 {
 618         int ret = -1;
 619         struct vga_device *vgadev;
 620         unsigned long flags;
 621
 622         spin_lock_irqsave(&vga_lock, flags);
 623         vgadev = vgadev_find(pdev);
 624         if (!vgadev)
 625                 goto bail;
 626
 627         vgadev->irq_set_state = irq_set_state;
 628         vgadev->set_vga_decode = set_vga_decode;
 629         vgadev->cookie = cookie;
 630         ret = 0;
 631
 632 bail:
 633         spin_unlock_irqrestore(&vga_lock, flags);
 634         return ret;
 635
 636 }
 637 EXPORT_SYMBOL(vga_client_register);
 638
 639 /*
 640  * Char driver implementation
 641  *
 642  * Semantics is:
 643  *
 644  *  open       : open user instance of the arbitrer. by default, it's
 645  *                attached to the default VGA device of the system.
 646  *
 647  *  close      : close user instance, release locks
 648  *
 649  *  read       : return a string indicating the status of the target.
 650  *                an IO state string is of the form {io,mem,io+mem,none},
 651  *                mc and ic are respectively mem and io lock counts (for
 652  *                debugging/diagnostic only). "decodes" indicate what the
 653  *                card currently decodes, "owns" indicates what is currently
 654  *                enabled on it, and "locks" indicates what is locked by this
 655  *                card. If the card is unplugged, we get "invalid" then for
 656  *                card_ID and an -ENODEV error is returned for any command
 657  *                until a new card is targeted
 658  *
 659  *   "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
 660  *
 661  * write       : write a command to the arbiter. List of commands is:
 662  *
 663  *   target <card_ID>   : switch target to card <card_ID> (see below)
 664  *   lock <io_state>    : acquires locks on target ("none" is invalid io_state)
 665  *   trylock <io_state> : non-blocking acquire locks on target
 666  *   unlock <io_state>  : release locks on target
 667  *   unlock all         : release all locks on target held by this user
 668  *   decodes <io_state> : set the legacy decoding attributes for the card
 669  *
 670  * poll         : event if something change on any card (not just the target)
 671  *
 672  * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
 673  * to go back to the system default card (TODO: not implemented yet).
 674  * Currently, only PCI is supported as a prefix, but the userland API may
 675  * support other bus types in the future, even if the current kernel
 676  * implementation doesn't.
 677  *
 678  * Note about locks:
 679  *
 680  * The driver keeps track of which user has what locks on which card. It
 681  * supports stacking, like the kernel one. This complexifies the implementation
 682  * a bit, but makes the arbiter more tolerant to userspace problems and able
 683  * to properly cleanup in all cases when a process dies.
 684  * Currently, a max of 16 cards simultaneously can have locks issued from
 685  * userspace for a given user (file descriptor instance) of the arbiter.
 686  *
 687  * If the device is hot-unplugged, there is a hook inside the module to notify
 688  * they being added/removed in the system and automatically added/removed in
 689  * the arbiter.
 690  */
 691
 692 #define MAX_USER_CARDS         CONFIG_VGA_ARB_MAX_GPUS
 693 #define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
 694
 695 /*
 696  * Each user has an array of these, tracking which cards have locks
 697  */
 698 struct vga_arb_user_card {
 699         struct pci_dev *pdev;
 700         unsigned int mem_cnt;
 701         unsigned int io_cnt;
 702 };
 703
 704 struct vga_arb_private {
 705         struct list_head list;
 706         struct pci_dev *target;
 707         struct vga_arb_user_card cards[MAX_USER_CARDS];
 708         spinlock_t lock;
 709 };
 710
 711 static LIST_HEAD(vga_user_list);
 712 static DEFINE_SPINLOCK(vga_user_lock);
 713
 714
 715 /*
 716  * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
 717  * returns the respective values. If the string is not in this format,
 718  * it returns 0.
 719  */
 720 static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
 721                                unsigned int *bus, unsigned int *devfn)
 722 {
 723         int n;
 724         unsigned int slot, func;
 725
 726
 727         n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
 728         if (n != 4)
 729                 return 0;
 730
 731         *devfn = PCI_DEVFN(slot, func);
 732
 733         return 1;
 734 }
 735
 736 static ssize_t vga_arb_read(struct file *file, char __user * buf,
 737                             size_t count, loff_t *ppos)
 738 {
 739         struct vga_arb_private *priv = file->private_data;
 740         struct vga_device *vgadev;
 741         struct pci_dev *pdev;
 742         unsigned long flags;
 743         size_t len;
 744         int rc;
 745         char *lbuf;
 746
 747         lbuf = kmalloc(1024, GFP_KERNEL);
 748         if (lbuf == NULL)
 749                 return -ENOMEM;
 750
 751         /* Shields against vga_arb_device_card_gone (pci_dev going
 752          * away), and allows access to vga list
 753          */
 754         spin_lock_irqsave(&vga_lock, flags);
 755
 756         /* If we are targetting the default, use it */
 757         pdev = priv->target;
 758         if (pdev == NULL || pdev == PCI_INVALID_CARD) {
 759                 spin_unlock_irqrestore(&vga_lock, flags);
 760                 len = sprintf(lbuf, "invalid");
 761                 goto done;
 762         }
 763
 764         /* Find card vgadev structure */
 765         vgadev = vgadev_find(pdev);
 766         if (vgadev == NULL) {
 767                 /* Wow, it's not in the list, that shouldn't happen,
 768                  * let's fix us up and return invalid card
 769                  */
 770                 if (pdev == priv->target)
 771                         vga_arb_device_card_gone(pdev);
 772                 spin_unlock_irqrestore(&vga_lock, flags);
 773                 len = sprintf(lbuf, "invalid");
 774                 goto done;
 775         }
 776
 777         /* Fill the buffer with infos */
 778         len = snprintf(lbuf, 1024,
 779                        "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
 780                        vga_decode_count, pci_name(pdev),
 781                        vga_iostate_to_str(vgadev->decodes),
 782                        vga_iostate_to_str(vgadev->owns),
 783                        vga_iostate_to_str(vgadev->locks),
 784                        vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
 785
 786         spin_unlock_irqrestore(&vga_lock, flags);
 787 done:
 788
 789         /* Copy that to user */
 790         if (len > count)
 791                 len = count;
 792         rc = copy_to_user(buf, lbuf, len);
 793         kfree(lbuf);
 794         if (rc)
 795                 return -EFAULT;
 796         return len;
 797 }
 798
 799 /*
 800  * TODO: To avoid parsing inside kernel and to improve the speed we may
 801  * consider use ioctl here
 802  */
 803 static ssize_t vga_arb_write(struct file *file, const char __user * buf,
 804                              size_t count, loff_t *ppos)
 805 {
 806         struct vga_arb_private *priv = file->private_data;
 807         struct vga_arb_user_card *uc = NULL;
 808         struct pci_dev *pdev;
 809
 810         unsigned int io_state;
 811
 812         char *kbuf, *curr_pos;
 813         size_t remaining = count;
 814
 815         int ret_val;
 816         int i;
 817
 818
 819         kbuf = kmalloc(count + 1, GFP_KERNEL);
 820         if (!kbuf)
 821                 return -ENOMEM;
 822
 823         if (copy_from_user(kbuf, buf, count)) {
 824                 kfree(kbuf);
 825                 return -EFAULT;
 826         }
 827         curr_pos = kbuf;
 828         kbuf[count] = '\0';     /* Just to make sure... */
 829
 830         if (strncmp(curr_pos, "lock ", 5) == 0) {
 831                 curr_pos += 5;
 832                 remaining -= 5;
 833
 834                 pr_devel("client 0x%p called 'lock'\n", priv);
 835
 836                 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
 837                         ret_val = -EPROTO;
 838                         goto done;
 839                 }
 840                 if (io_state == VGA_RSRC_NONE) {
 841                         ret_val = -EPROTO;
 842                         goto done;
 843                 }
 844
 845                 pdev = priv->target;
 846                 if (priv->target == NULL) {
 847                         ret_val = -ENODEV;
 848                         goto done;
 849                 }
 850
 851                 vga_get_uninterruptible(pdev, io_state);
 852
 853                 /* Update the client's locks lists... */
 854                 for (i = 0; i < MAX_USER_CARDS; i++) {
 855                         if (priv->cards[i].pdev == pdev) {
 856                                 if (io_state & VGA_RSRC_LEGACY_IO)
 857                                         priv->cards[i].io_cnt++;
 858                                 if (io_state & VGA_RSRC_LEGACY_MEM)
 859                                         priv->cards[i].mem_cnt++;
 860                                 break;
 861                         }
 862                 }
 863
 864                 ret_val = count;
 865                 goto done;
 866         } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
 867                 curr_pos += 7;
 868                 remaining -= 7;
 869
 870                 pr_devel("client 0x%p called 'unlock'\n", priv);
 871
 872                 if (strncmp(curr_pos, "all", 3) == 0)
 873                         io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
 874                 else {
 875                         if (!vga_str_to_iostate
 876                             (curr_pos, remaining, &io_state)) {
 877                                 ret_val = -EPROTO;
 878                                 goto done;
 879                         }
 880                         /* TODO: Add this?
 881                            if (io_state == VGA_RSRC_NONE) {
 882                            ret_val = -EPROTO;
 883                            goto done;
 884                            }
 885                           */
 886                 }
 887
 888                 pdev = priv->target;
 889                 if (priv->target == NULL) {
 890                         ret_val = -ENODEV;
 891                         goto done;
 892                 }
 893                 for (i = 0; i < MAX_USER_CARDS; i++) {
 894                         if (priv->cards[i].pdev == pdev)
 895                                 uc = &priv->cards[i];
 896                 }
 897
 898                 if (!uc)
 899                         return -EINVAL;
 900
 901                 if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0)
 902                         return -EINVAL;
 903
 904                 if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0)
 905                         return -EINVAL;
 906
 907                 vga_put(pdev, io_state);
 908
 909                 if (io_state & VGA_RSRC_LEGACY_IO)
 910                         uc->io_cnt--;
 911                 if (io_state & VGA_RSRC_LEGACY_MEM)
 912                         uc->mem_cnt--;
 913
 914                 ret_val = count;
 915                 goto done;
 916         } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
 917                 curr_pos += 8;
 918                 remaining -= 8;
 919
 920                 pr_devel("client 0x%p called 'trylock'\n", priv);
 921
 922                 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
 923                         ret_val = -EPROTO;
 924                         goto done;
 925                 }
 926                 /* TODO: Add this?
 927                    if (io_state == VGA_RSRC_NONE) {
 928                    ret_val = -EPROTO;
 929                    goto done;
 930                    }
 931                  */
 932
 933                 pdev = priv->target;
 934                 if (priv->target == NULL) {
 935                         ret_val = -ENODEV;
 936                         goto done;
 937                 }
 938
 939                 if (vga_tryget(pdev, io_state)) {
 940                         /* Update the client's locks lists... */
 941                         for (i = 0; i < MAX_USER_CARDS; i++) {
 942                                 if (priv->cards[i].pdev == pdev) {
 943                                         if (io_state & VGA_RSRC_LEGACY_IO)
 944                                                 priv->cards[i].io_cnt++;
 945                                         if (io_state & VGA_RSRC_LEGACY_MEM)
 946                                                 priv->cards[i].mem_cnt++;
 947                                         break;
 948                                 }
 949                         }
 950                         ret_val = count;
 951                         goto done;
 952                 } else {
 953                         ret_val = -EBUSY;
 954                         goto done;
 955                 }
 956
 957         } else if (strncmp(curr_pos, "target ", 7) == 0) {
 958                 struct pci_bus *pbus;
 959                 unsigned int domain, bus, devfn;
 960                 struct vga_device *vgadev;
 961
 962                 curr_pos += 7;
 963                 remaining -= 7;
 964                 pr_devel("client 0x%p called 'target'\n", priv);
 965                 /* if target is default */
 966                 if (!strncmp(curr_pos, "default", 7))
 967                         pdev = pci_dev_get(vga_default_device());
 968                 else {
 969                         if (!vga_pci_str_to_vars(curr_pos, remaining,
 970                                                  &domain, &bus, &devfn)) {
 971                                 ret_val = -EPROTO;
 972                                 goto done;
 973                         }
 974                         pr_devel("vgaarb: %s ==> %x:%x:%x.%x\n", curr_pos,
 975                                 domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
 976
 977                         pbus = pci_find_bus(domain, bus);
 978                         pr_devel("vgaarb: pbus %p\n", pbus);
 979                         if (pbus == NULL) {
 980                                 pr_err("vgaarb: invalid PCI domain and/or bus address %x:%x\n",
 981                                         domain, bus);
 982                                 ret_val = -ENODEV;
 983                                 goto done;
 984                         }
 985                         pdev = pci_get_slot(pbus, devfn);
 986                         pr_devel("vgaarb: pdev %p\n", pdev);
 987                         if (!pdev) {
 988                                 pr_err("vgaarb: invalid PCI address %x:%x\n",
 989                                         bus, devfn);
 990                                 ret_val = -ENODEV;
 991                                 goto done;
 992                         }
 993                 }
 994
 995                 vgadev = vgadev_find(pdev);
 996                 pr_devel("vgaarb: vgadev %p\n", vgadev);
 997                 if (vgadev == NULL) {
 998                         pr_err("vgaarb: this pci device is not a vga device\n");
 999                         pci_dev_put(pdev);
1000                         ret_val = -ENODEV;
1001                         goto done;
1002                 }
1003
1004                 priv->target = pdev;
1005                 for (i = 0; i < MAX_USER_CARDS; i++) {
1006                         if (priv->cards[i].pdev == pdev)
1007                                 break;
1008                         if (priv->cards[i].pdev == NULL) {
1009                                 priv->cards[i].pdev = pdev;
1010                                 priv->cards[i].io_cnt = 0;
1011                                 priv->cards[i].mem_cnt = 0;
1012                                 break;
1013                         }
1014                 }
1015                 if (i == MAX_USER_CARDS) {
1016                         pr_err("vgaarb: maximum user cards (%d) number reached!\n",
1017                                 MAX_USER_CARDS);
1018                         pci_dev_put(pdev);
1019                         /* XXX: which value to return? */
1020                         ret_val =  -ENOMEM;
1021                         goto done;
1022                 }
1023
1024                 ret_val = count;
1025                 pci_dev_put(pdev);
1026                 goto done;
1027
1028
1029         } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
1030                 curr_pos += 8;
1031                 remaining -= 8;
1032                 pr_devel("vgaarb: client 0x%p called 'decodes'\n", priv);
1033
1034                 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1035                         ret_val = -EPROTO;
1036                         goto done;
1037                 }
1038                 pdev = priv->target;
1039                 if (priv->target == NULL) {
1040                         ret_val = -ENODEV;
1041                         goto done;
1042                 }
1043
1044                 __vga_set_legacy_decoding(pdev, io_state, true);
1045                 ret_val = count;
1046                 goto done;
1047         }
1048         /* If we got here, the message written is not part of the protocol! */
1049         kfree(kbuf);
1050         return -EPROTO;
1051
1052 done:
1053         kfree(kbuf);
1054         return ret_val;
1055 }
1056
1057 static unsigned int vga_arb_fpoll(struct file *file, poll_table * wait)
1058 {
1059         struct vga_arb_private *priv = file->private_data;
1060
1061         pr_devel("%s\n", __func__);
1062
1063         if (priv == NULL)
1064                 return -ENODEV;
1065         poll_wait(file, &vga_wait_queue, wait);
1066         return POLLIN;
1067 }
1068
1069 static int vga_arb_open(struct inode *inode, struct file *file)
1070 {
1071         struct vga_arb_private *priv;
1072         unsigned long flags;
1073
1074         pr_devel("%s\n", __func__);
1075
1076         priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
1077         if (priv == NULL)
1078                 return -ENOMEM;
1079         memset(priv, 0, sizeof(*priv));
1080         spin_lock_init(&priv->lock);
1081         file->private_data = priv;
1082
1083         spin_lock_irqsave(&vga_user_lock, flags);
1084         list_add(&priv->list, &vga_user_list);
1085         spin_unlock_irqrestore(&vga_user_lock, flags);
1086
1087         /* Set the client' lists of locks */
1088         priv->target = vga_default_device(); /* Maybe this is still null! */
1089         priv->cards[0].pdev = priv->target;
1090         priv->cards[0].io_cnt = 0;
1091         priv->cards[0].mem_cnt = 0;
1092
1093
1094         return 0;
1095 }
1096
1097 static int vga_arb_release(struct inode *inode, struct file *file)
1098 {
1099         struct vga_arb_private *priv = file->private_data;
1100         struct vga_arb_user_card *uc;
1101         unsigned long flags;
1102         int i;
1103
1104         pr_devel("%s\n", __func__);
1105
1106         if (priv == NULL)
1107                 return -ENODEV;
1108
1109         spin_lock_irqsave(&vga_user_lock, flags);
1110         list_del(&priv->list);
1111         for (i = 0; i < MAX_USER_CARDS; i++) {
1112                 uc = &priv->cards[i];
1113                 if (uc->pdev == NULL)
1114                         continue;
1115                 pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
1116                          uc->io_cnt, uc->mem_cnt);
1117                 while (uc->io_cnt--)
1118                         vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
1119                 while (uc->mem_cnt--)
1120                         vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
1121         }
1122         spin_unlock_irqrestore(&vga_user_lock, flags);
1123
1124         kfree(priv);
1125
1126         return 0;
1127 }
1128
1129 static void vga_arb_device_card_gone(struct pci_dev *pdev)
1130 {
1131 }
1132
1133 /*
1134  * callback any registered clients to let them know we have a
1135  * change in VGA cards
1136  */
1137 static void vga_arbiter_notify_clients(void)
1138 {
1139         struct vga_device *vgadev;
1140         unsigned long flags;
1141         uint32_t new_decodes;
1142         bool new_state;
1143
1144         if (!vga_arbiter_used)
1145                 return;
1146
1147         spin_lock_irqsave(&vga_lock, flags);
1148         list_for_each_entry(vgadev, &vga_list, list) {
1149                 if (vga_count > 1)
1150                         new_state = false;
1151                 else
1152                         new_state = true;
1153                 if (vgadev->set_vga_decode) {
1154                         new_decodes = vgadev->set_vga_decode(vgadev->cookie, new_state);
1155                         vga_update_device_decodes(vgadev, new_decodes);
1156                 }
1157         }
1158         spin_unlock_irqrestore(&vga_lock, flags);
1159 }
1160
1161 static int pci_notify(struct notifier_block *nb, unsigned long action,
1162                       void *data)
1163 {
1164         struct device *dev = data;
1165         struct pci_dev *pdev = to_pci_dev(dev);
1166         bool notify = false;
1167
1168         pr_devel("%s\n", __func__);
1169
1170         /* For now we're only intereted in devices added and removed. I didn't
1171          * test this thing here, so someone needs to double check for the
1172          * cases of hotplugable vga cards. */
1173         if (action == BUS_NOTIFY_ADD_DEVICE)
1174                 notify = vga_arbiter_add_pci_device(pdev);
1175         else if (action == BUS_NOTIFY_DEL_DEVICE)
1176                 notify = vga_arbiter_del_pci_device(pdev);
1177
1178         if (notify)
1179                 vga_arbiter_notify_clients();
1180         return 0;
1181 }
1182
1183 static struct notifier_block pci_notifier = {
1184         .notifier_call = pci_notify,
1185 };
1186
1187 static const struct file_operations vga_arb_device_fops = {
1188         .read = vga_arb_read,
1189         .write = vga_arb_write,
1190         .poll = vga_arb_fpoll,
1191         .open = vga_arb_open,
1192         .release = vga_arb_release,
1193 };
1194
1195 static struct miscdevice vga_arb_device = {
1196         MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
1197 };
1198
1199 static int __init vga_arb_device_init(void)
1200 {
1201         int rc;
1202         struct pci_dev *pdev;
1203
1204         rc = misc_register(&vga_arb_device);
1205         if (rc < 0)
1206                 pr_err("vgaarb: error %d registering device\n", rc);
1207
1208         bus_register_notifier(&pci_bus_type, &pci_notifier);
1209
1210         /* We add all pci devices satisfying vga class in the arbiter by
1211          * default */
1212         pdev = NULL;
1213         while ((pdev =
1214                 pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
1215                                PCI_ANY_ID, pdev)) != NULL)
1216                 vga_arbiter_add_pci_device(pdev);
1217
1218         pr_info("vgaarb: loaded\n");
1219         return rc;
1220 }
1221 subsys_initcall(vga_arb_device_init);