vgaarb.c

   1// SPDX-License-Identifier: MIT
   2/*
   3 * vgaarb.c: Implements VGA arbitration. For details refer to
   4 * Documentation/gpu/vgaarbiter.rst
   5 *
   6 * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
   7 * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
   8 * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
   9 */
  10
  11#define pr_fmt(fmt) "vgaarb: " fmt
  12
  13#define vgaarb_dbg(dev, fmt, arg...)	dev_dbg(dev, "vgaarb: " fmt, ##arg)
  14#define vgaarb_info(dev, fmt, arg...)	dev_info(dev, "vgaarb: " fmt, ##arg)
  15#define vgaarb_err(dev, fmt, arg...)	dev_err(dev, "vgaarb: " fmt, ##arg)
  16
  17#include <linux/module.h>
  18#include <linux/kernel.h>
  19#include <linux/pci.h>
  20#include <linux/errno.h>
  21#include <linux/init.h>
  22#include <linux/list.h>
  23#include <linux/sched/signal.h>
  24#include <linux/wait.h>
  25#include <linux/spinlock.h>
  26#include <linux/poll.h>
  27#include <linux/miscdevice.h>
  28#include <linux/slab.h>
  29#include <linux/screen_info.h>
  30#include <linux/vt.h>
  31#include <linux/console.h>
  32#include <linux/acpi.h>
  33#include <linux/uaccess.h>
  34#include <linux/vgaarb.h>
  35
  36static void vga_arbiter_notify_clients(void);
  37
  38/*
  39 * We keep a list of all VGA devices in the system to speed
  40 * up the various operations of the arbiter
  41 */
  42struct vga_device {
  43	struct list_head list;
  44	struct pci_dev *pdev;
  45	unsigned int decodes;		/* what it decodes */
  46	unsigned int owns;		/* what it owns */
  47	unsigned int locks;		/* what it locks */
  48	unsigned int io_lock_cnt;	/* legacy IO lock count */
  49	unsigned int mem_lock_cnt;	/* legacy MEM lock count */
  50	unsigned int io_norm_cnt;	/* normal IO count */
  51	unsigned int mem_norm_cnt;	/* normal MEM count */
  52	bool bridge_has_one_vga;
  53	bool is_firmware_default;	/* device selected by firmware */
  54	unsigned int (*set_decode)(struct pci_dev *pdev, bool decode);
  55};
  56
  57static LIST_HEAD(vga_list);
  58static int vga_count, vga_decode_count;
  59static bool vga_arbiter_used;
  60static DEFINE_SPINLOCK(vga_lock);
  61static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
  62
  63static const char *vga_iostate_to_str(unsigned int iostate)
  64{
  65	/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
  66	iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
  67	switch (iostate) {
  68	case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
  69		return "io+mem";
  70	case VGA_RSRC_LEGACY_IO:
  71		return "io";
  72	case VGA_RSRC_LEGACY_MEM:
  73		return "mem";
  74	}
  75	return "none";
  76}
  77
  78static int vga_str_to_iostate(char *buf, int str_size, unsigned int *io_state)
  79{
  80	/*
  81	 * In theory, we could hand out locks on IO and MEM separately to
  82	 * userspace, but this can cause deadlocks.
  83	 */
  84	if (strncmp(buf, "none", 4) == 0) {
  85		*io_state = VGA_RSRC_NONE;
  86		return 1;
  87	}
  88
  89	/* XXX We're not checking the str_size! */
  90	if (strncmp(buf, "io+mem", 6) == 0)
  91		goto both;
  92	else if (strncmp(buf, "io", 2) == 0)
  93		goto both;
  94	else if (strncmp(buf, "mem", 3) == 0)
  95		goto both;
  96	return 0;
  97both:
  98	*io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
  99	return 1;
 100}
 101
 102/* This is only used as a cookie, it should not be dereferenced */
 103static struct pci_dev *vga_default;
 104
 105/* Find somebody in our list */
 106static struct vga_device *vgadev_find(struct pci_dev *pdev)
 107{
 108	struct vga_device *vgadev;
 109
 110	list_for_each_entry(vgadev, &vga_list, list)
 111		if (pdev == vgadev->pdev)
 112			return vgadev;
 113	return NULL;
 114}
 115
 116/**
 117 * vga_default_device - return the default VGA device, for vgacon
 118 *
 119 * This can be defined by the platform. The default implementation is
 120 * rather dumb and will probably only work properly on single VGA card
 121 * setups and/or x86 platforms.
 122 *
 123 * If your VGA default device is not PCI, you'll have to return NULL here.
 124 * In this case, I assume it will not conflict with any PCI card. If this
 125 * is not true, I'll have to define two arch hooks for enabling/disabling
 126 * the VGA default device if that is possible. This may be a problem with
 127 * real _ISA_ VGA cards, in addition to a PCI one. I don't know at this
 128 * point how to deal with that card. Can their IOs be disabled at all? If
 129 * not, then I suppose it's a matter of having the proper arch hook telling
 130 * us about it, so we basically never allow anybody to succeed a vga_get().
 131 */
 132struct pci_dev *vga_default_device(void)
 133{
 134	return vga_default;
 135}
 136EXPORT_SYMBOL_GPL(vga_default_device);
 137
 138void vga_set_default_device(struct pci_dev *pdev)
 139{
 140	if (vga_default == pdev)
 141		return;
 142
 143	pci_dev_put(vga_default);
 144	vga_default = pci_dev_get(pdev);
 145}
 146
 147/**
 148 * vga_remove_vgacon - deactivate VGA console
 149 *
 150 * Unbind and unregister vgacon in case pdev is the default VGA device.
 151 * Can be called by GPU drivers on initialization to make sure VGA register
 152 * access done by vgacon will not disturb the device.
 153 *
 154 * @pdev: PCI device.
 155 */
 156#if !defined(CONFIG_VGA_CONSOLE)
 157int vga_remove_vgacon(struct pci_dev *pdev)
 158{
 159	return 0;
 160}
 161#elif !defined(CONFIG_DUMMY_CONSOLE)
 162int vga_remove_vgacon(struct pci_dev *pdev)
 163{
 164	return -ENODEV;
 165}
 166#else
 167int vga_remove_vgacon(struct pci_dev *pdev)
 168{
 169	int ret = 0;
 170
 171	if (pdev != vga_default)
 172		return 0;
 173	vgaarb_info(&pdev->dev, "deactivate vga console\n");
 174
 175	console_lock();
 176	if (con_is_bound(&vga_con))
 177		ret = do_take_over_console(&dummy_con, 0,
 178					   MAX_NR_CONSOLES - 1, 1);
 179	if (ret == 0) {
 180		ret = do_unregister_con_driver(&vga_con);
 181
 182		/* Ignore "already unregistered". */
 183		if (ret == -ENODEV)
 184			ret = 0;
 185	}
 186	console_unlock();
 187
 188	return ret;
 189}
 190#endif
 191EXPORT_SYMBOL(vga_remove_vgacon);
 192
 193/*
 194 * If we don't ever use VGA arbitration, we should avoid turning off
 195 * anything anywhere due to old X servers getting confused about the boot
 196 * device not being VGA.
 197 */
 198static void vga_check_first_use(void)
 199{
 200	/*
 201	 * Inform all GPUs in the system that VGA arbitration has occurred
 202	 * so they can disable resources if possible.
 203	 */
 204	if (!vga_arbiter_used) {
 205		vga_arbiter_used = true;
 206		vga_arbiter_notify_clients();
 207	}
 208}
 209
 210static struct vga_device *__vga_tryget(struct vga_device *vgadev,
 211				       unsigned int rsrc)
 212{
 213	struct device *dev = &vgadev->pdev->dev;
 214	unsigned int wants, legacy_wants, match;
 215	struct vga_device *conflict;
 216	unsigned int pci_bits;
 217	u32 flags = 0;
 218
 219	/*
 220	 * Account for "normal" resources to lock. If we decode the legacy,
 221	 * counterpart, we need to request it as well
 222	 */
 223	if ((rsrc & VGA_RSRC_NORMAL_IO) &&
 224	    (vgadev->decodes & VGA_RSRC_LEGACY_IO))
 225		rsrc |= VGA_RSRC_LEGACY_IO;
 226	if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
 227	    (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
 228		rsrc |= VGA_RSRC_LEGACY_MEM;
 229
 230	vgaarb_dbg(dev, "%s: %d\n", __func__, rsrc);
 231	vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns);
 232
 233	/* Check what resources we need to acquire */
 234	wants = rsrc & ~vgadev->owns;
 235
 236	/* We already own everything, just mark locked & bye bye */
 237	if (wants == 0)
 238		goto lock_them;
 239
 240	/*
 241	 * We don't need to request a legacy resource, we just enable
 242	 * appropriate decoding and go.
 243	 */
 244	legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
 245	if (legacy_wants == 0)
 246		goto enable_them;
 247
 248	/* Ok, we don't, let's find out who we need to kick off */
 249	list_for_each_entry(conflict, &vga_list, list) {
 250		unsigned int lwants = legacy_wants;
 251		unsigned int change_bridge = 0;
 252
 253		/* Don't conflict with myself */
 254		if (vgadev == conflict)
 255			continue;
 256
 257		/*
 258		 * We have a possible conflict. Before we go further, we must
 259		 * check if we sit on the same bus as the conflicting device.
 260		 * If we don't, then we must tie both IO and MEM resources
 261		 * together since there is only a single bit controlling
 262		 * VGA forwarding on P2P bridges.
 263		 */
 264		if (vgadev->pdev->bus != conflict->pdev->bus) {
 265			change_bridge = 1;
 266			lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
 267		}
 268
 269		/*
 270		 * Check if the guy has a lock on the resource. If he does,
 271		 * return the conflicting entry.
 272		 */
 273		if (conflict->locks & lwants)
 274			return conflict;
 275
 276		/*
 277		 * Ok, now check if it owns the resource we want.  We can
 278		 * lock resources that are not decoded; therefore a device
 279		 * can own resources it doesn't decode.
 280		 */
 281		match = lwants & conflict->owns;
 282		if (!match)
 283			continue;
 284
 285		/*
 286		 * Looks like he doesn't have a lock, we can steal them
 287		 * from him.
 288		 */
 289
 290		flags = 0;
 291		pci_bits = 0;
 292
 293		/*
 294		 * If we can't control legacy resources via the bridge, we
 295		 * also need to disable normal decoding.
 296		 */
 297		if (!conflict->bridge_has_one_vga) {
 298			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)
 299				pci_bits |= PCI_COMMAND_MEMORY;
 300			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)
 301				pci_bits |= PCI_COMMAND_IO;
 302
 303			if (pci_bits)
 304				flags |= PCI_VGA_STATE_CHANGE_DECODES;
 305		}
 306
 307		if (change_bridge)
 308			flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
 309
 310		pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
 311		conflict->owns &= ~match;
 312
 313		/* If we disabled normal decoding, reflect it in owns */
 314		if (pci_bits & PCI_COMMAND_MEMORY)
 315			conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
 316		if (pci_bits & PCI_COMMAND_IO)
 317			conflict->owns &= ~VGA_RSRC_NORMAL_IO;
 318	}
 319
 320enable_them:
 321	/*
 322	 * Ok, we got it, everybody conflicting has been disabled, let's
 323	 * enable us.  Mark any bits in "owns" regardless of whether we
 324	 * decoded them.  We can lock resources we don't decode, therefore
 325	 * we must track them via "owns".
 326	 */
 327	flags = 0;
 328	pci_bits = 0;
 329
 330	if (!vgadev->bridge_has_one_vga) {
 331		flags |= PCI_VGA_STATE_CHANGE_DECODES;
 332		if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
 333			pci_bits |= PCI_COMMAND_MEMORY;
 334		if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
 335			pci_bits |= PCI_COMMAND_IO;
 336	}
 337	if (wants & VGA_RSRC_LEGACY_MASK)
 338		flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
 339
 340	pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);
 341
 342	vgadev->owns |= wants;
 343lock_them:
 344	vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
 345	if (rsrc & VGA_RSRC_LEGACY_IO)
 346		vgadev->io_lock_cnt++;
 347	if (rsrc & VGA_RSRC_LEGACY_MEM)
 348		vgadev->mem_lock_cnt++;
 349	if (rsrc & VGA_RSRC_NORMAL_IO)
 350		vgadev->io_norm_cnt++;
 351	if (rsrc & VGA_RSRC_NORMAL_MEM)
 352		vgadev->mem_norm_cnt++;
 353
 354	return NULL;
 355}
 356
 357static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
 358{
 359	struct device *dev = &vgadev->pdev->dev;
 360	unsigned int old_locks = vgadev->locks;
 361
 362	vgaarb_dbg(dev, "%s\n", __func__);
 363
 364	/*
 365	 * Update our counters and account for equivalent legacy resources
 366	 * if we decode them.
 367	 */
 368	if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
 369		vgadev->io_norm_cnt--;
 370		if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
 371			rsrc |= VGA_RSRC_LEGACY_IO;
 372	}
 373	if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
 374		vgadev->mem_norm_cnt--;
 375		if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
 376			rsrc |= VGA_RSRC_LEGACY_MEM;
 377	}
 378	if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
 379		vgadev->io_lock_cnt--;
 380	if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
 381		vgadev->mem_lock_cnt--;
 382
 383	/*
 384	 * Just clear lock bits, we do lazy operations so we don't really
 385	 * have to bother about anything else at this point.
 386	 */
 387	if (vgadev->io_lock_cnt == 0)
 388		vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
 389	if (vgadev->mem_lock_cnt == 0)
 390		vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
 391
 392	/*
 393	 * Kick the wait queue in case somebody was waiting if we actually
 394	 * released something.
 395	 */
 396	if (old_locks != vgadev->locks)
 397		wake_up_all(&vga_wait_queue);
 398}
 399
 400/**
 401 * vga_get - acquire & lock VGA resources
 402 * @pdev: PCI device of the VGA card or NULL for the system default
 403 * @rsrc: bit mask of resources to acquire and lock
 404 * @interruptible: blocking should be interruptible by signals ?
 405 *
 406 * Acquire VGA resources for the given card and mark those resources
 407 * locked. If the resources requested are "normal" (and not legacy)
 408 * resources, the arbiter will first check whether the card is doing legacy
 409 * decoding for that type of resource. If yes, the lock is "converted" into
 410 * a legacy resource lock.
 411 *
 412 * The arbiter will first look for all VGA cards that might conflict and disable
 413 * their IOs and/or Memory access, including VGA forwarding on P2P bridges if
 414 * necessary, so that the requested resources can be used. Then, the card is
 415 * marked as locking these resources and the IO and/or Memory accesses are
 416 * enabled on the card (including VGA forwarding on parent P2P bridges if any).
 417 *
 418 * This function will block if some conflicting card is already locking one of
 419 * the required resources (or any resource on a different bus segment, since P2P
 420 * bridges don't differentiate VGA memory and IO afaik). You can indicate
 421 * whether this blocking should be interruptible by a signal (for userland
 422 * interface) or not.
 423 *
 424 * Must not be called at interrupt time or in atomic context.  If the card
 425 * already owns the resources, the function succeeds.  Nested calls are
 426 * supported (a per-resource counter is maintained)
 427 *
 428 * On success, release the VGA resource again with vga_put().
 429 *
 430 * Returns:
 431 *
 432 * 0 on success, negative error code on failure.
 433 */
 434int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
 435{
 436	struct vga_device *vgadev, *conflict;
 437	unsigned long flags;
 438	wait_queue_entry_t wait;
 439	int rc = 0;
 440
 441	vga_check_first_use();
 442	/* The caller should check for this, but let's be sure */
 443	if (pdev == NULL)
 444		pdev = vga_default_device();
 445	if (pdev == NULL)
 446		return 0;
 447
 448	for (;;) {
 449		spin_lock_irqsave(&vga_lock, flags);
 450		vgadev = vgadev_find(pdev);
 451		if (vgadev == NULL) {
 452			spin_unlock_irqrestore(&vga_lock, flags);
 453			rc = -ENODEV;
 454			break;
 455		}
 456		conflict = __vga_tryget(vgadev, rsrc);
 457		spin_unlock_irqrestore(&vga_lock, flags);
 458		if (conflict == NULL)
 459			break;
 460
 461		/*
 462		 * We have a conflict; we wait until somebody kicks the
 463		 * work queue. Currently we have one work queue that we
 464		 * kick each time some resources are released, but it would
 465		 * be fairly easy to have a per-device one so that we only
 466		 * need to attach to the conflicting device.
 467		 */
 468		init_waitqueue_entry(&wait, current);
 469		add_wait_queue(&vga_wait_queue, &wait);
 470		set_current_state(interruptible ?
 471				  TASK_INTERRUPTIBLE :
 472				  TASK_UNINTERRUPTIBLE);
 473		if (interruptible && signal_pending(current)) {
 474			__set_current_state(TASK_RUNNING);
 475			remove_wait_queue(&vga_wait_queue, &wait);
 476			rc = -ERESTARTSYS;
 477			break;
 478		}
 479		schedule();
 480		remove_wait_queue(&vga_wait_queue, &wait);
 481	}
 482	return rc;
 483}
 484EXPORT_SYMBOL(vga_get);
 485
 486/**
 487 * vga_tryget - try to acquire & lock legacy VGA resources
 488 * @pdev: PCI device of VGA card or NULL for system default
 489 * @rsrc: bit mask of resources to acquire and lock
 490 *
 491 * Perform the same operation as vga_get(), but return an error (-EBUSY)
 492 * instead of blocking if the resources are already locked by another card.
 493 * Can be called in any context.
 494 *
 495 * On success, release the VGA resource again with vga_put().
 496 *
 497 * Returns:
 498 *
 499 * 0 on success, negative error code on failure.
 500 */
 501static int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
 502{
 503	struct vga_device *vgadev;
 504	unsigned long flags;
 505	int rc = 0;
 506
 507	vga_check_first_use();
 508
 509	/* The caller should check for this, but let's be sure */
 510	if (pdev == NULL)
 511		pdev = vga_default_device();
 512	if (pdev == NULL)
 513		return 0;
 514	spin_lock_irqsave(&vga_lock, flags);
 515	vgadev = vgadev_find(pdev);
 516	if (vgadev == NULL) {
 517		rc = -ENODEV;
 518		goto bail;
 519	}
 520	if (__vga_tryget(vgadev, rsrc))
 521		rc = -EBUSY;
 522bail:
 523	spin_unlock_irqrestore(&vga_lock, flags);
 524	return rc;
 525}
 526
 527/**
 528 * vga_put - release lock on legacy VGA resources
 529 * @pdev: PCI device of VGA card or NULL for system default
 530 * @rsrc: bit mask of resource to release
 531 *
 532 * Release resources previously locked by vga_get() or vga_tryget().  The
 533 * resources aren't disabled right away, so that a subsequent vga_get() on
 534 * the same card will succeed immediately.  Resources have a counter, so
 535 * locks are only released if the counter reaches 0.
 536 */
 537void vga_put(struct pci_dev *pdev, unsigned int rsrc)
 538{
 539	struct vga_device *vgadev;
 540	unsigned long flags;
 541
 542	/* The caller should check for this, but let's be sure */
 543	if (pdev == NULL)
 544		pdev = vga_default_device();
 545	if (pdev == NULL)
 546		return;
 547	spin_lock_irqsave(&vga_lock, flags);
 548	vgadev = vgadev_find(pdev);
 549	if (vgadev == NULL)
 550		goto bail;
 551	__vga_put(vgadev, rsrc);
 552bail:
 553	spin_unlock_irqrestore(&vga_lock, flags);
 554}
 555EXPORT_SYMBOL(vga_put);
 556
 557static bool vga_is_firmware_default(struct pci_dev *pdev)
 558{
 559#if defined CONFIG_X86
 560	return pdev == screen_info_pci_dev(&screen_info);
 561#else
 562	return false;
 563#endif
 564}
 565
 566static bool vga_arb_integrated_gpu(struct device *dev)
 567{
 568#if defined(CONFIG_ACPI)
 569	struct acpi_device *adev = ACPI_COMPANION(dev);
 570
 571	return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);
 572#else
 573	return false;
 574#endif
 575}
 576
 577/*
 578 * Return true if vgadev is a better default VGA device than the best one
 579 * we've seen so far.
 580 */
 581static bool vga_is_boot_device(struct vga_device *vgadev)
 582{
 583	struct vga_device *boot_vga = vgadev_find(vga_default_device());
 584	struct pci_dev *pdev = vgadev->pdev;
 585	u16 cmd, boot_cmd;
 586
 587	/*
 588	 * We select the default VGA device in this order:
 589	 *   Firmware framebuffer (see vga_arb_select_default_device())
 590	 *   Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)
 591	 *   Non-legacy integrated device (see vga_arb_select_default_device())
 592	 *   Non-legacy discrete device (see vga_arb_select_default_device())
 593	 *   Other device (see vga_arb_select_default_device())
 594	 */
 595
 596	/*
 597	 * We always prefer a firmware default device, so if we've already
 598	 * found one, there's no need to consider vgadev.
 599	 */
 600	if (boot_vga && boot_vga->is_firmware_default)
 601		return false;
 602
 603	if (vga_is_firmware_default(pdev)) {
 604		vgadev->is_firmware_default = true;
 605		return true;
 606	}
 607
 608	/*
 609	 * A legacy VGA device has MEM and IO enabled and any bridges
 610	 * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy
 611	 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are
 612	 * routed to it.
 613	 *
 614	 * We use the first one we find, so if we've already found one,
 615	 * vgadev is no better.
 616	 */
 617	if (boot_vga &&
 618	    (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
 619		return false;
 620
 621	if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
 622		return true;
 623
 624	/*
 625	 * If we haven't found a legacy VGA device, accept a non-legacy
 626	 * device.  It may have either IO or MEM enabled, and bridges may
 627	 * not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to
 628	 * use legacy VGA resources.  Prefer an integrated GPU over others.
 629	 */
 630	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
 631	if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
 632
 633		/*
 634		 * An integrated GPU overrides a previous non-legacy
 635		 * device.  We expect only a single integrated GPU, but if
 636		 * there are more, we use the *last* because that was the
 637		 * previous behavior.
 638		 */
 639		if (vga_arb_integrated_gpu(&pdev->dev))
 640			return true;
 641
 642		/*
 643		 * We prefer the first non-legacy discrete device we find.
 644		 * If we already found one, vgadev is no better.
 645		 */
 646		if (boot_vga) {
 647			pci_read_config_word(boot_vga->pdev, PCI_COMMAND,
 648					     &boot_cmd);
 649			if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
 650				return false;
 651		}
 652		return true;
 653	}
 654
 655	return false;
 656}
 657
 658/*
 659 * Rules for using a bridge to control a VGA descendant decoding: if a bridge
 660 * has only one VGA descendant then it can be used to control the VGA routing
 661 * for that device. It should always use the bridge closest to the device to
 662 * control it. If a bridge has a direct VGA descendant, but also have a sub-
 663 * bridge VGA descendant then we cannot use that bridge to control the direct
 664 * VGA descendant. So for every device we register, we need to iterate all
 665 * its parent bridges so we can invalidate any devices using them properly.
 666 */
 667static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
 668{
 669	struct vga_device *same_bridge_vgadev;
 670	struct pci_bus *new_bus, *bus;
 671	struct pci_dev *new_bridge, *bridge;
 672
 673	vgadev->bridge_has_one_vga = true;
 674
 675	if (list_empty(&vga_list)) {
 676		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
 677		return;
 678	}
 679
 680	/* Iterate the new device's bridge hierarchy */
 681	new_bus = vgadev->pdev->bus;
 682	while (new_bus) {
 683		new_bridge = new_bus->self;
 684
 685		/* Go through list of devices already registered */
 686		list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
 687			bus = same_bridge_vgadev->pdev->bus;
 688			bridge = bus->self;
 689
 690			/* See if it shares a bridge with this device */
 691			if (new_bridge == bridge) {
 692				/*
 693				 * If its direct parent bridge is the same
 694				 * as any bridge of this device then it can't
 695				 * be used for that device.
 696				 */
 697				same_bridge_vgadev->bridge_has_one_vga = false;
 698			}
 699
 700			/*
 701			 * Now iterate the previous device's bridge hierarchy.
 702			 * If the new device's parent bridge is in the other
 703			 * device's hierarchy, we can't use it to control this
 704			 * device.
 705			 */
 706			while (bus) {
 707				bridge = bus->self;
 708
 709				if (bridge && bridge == vgadev->pdev->bus->self)
 710					vgadev->bridge_has_one_vga = false;
 711
 712				bus = bus->parent;
 713			}
 714		}
 715		new_bus = new_bus->parent;
 716	}
 717
 718	if (vgadev->bridge_has_one_vga)
 719		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
 720	else
 721		vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
 722}
 723
 724/*
 725 * Currently, we assume that the "initial" setup of the system is not sane,
 726 * that is, we come up with conflicting devices and let the arbiter's
 727 * client decide if devices decodes legacy things or not.
 728 */
 729static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 730{
 731	struct vga_device *vgadev;
 732	unsigned long flags;
 733	struct pci_bus *bus;
 734	struct pci_dev *bridge;
 735	u16 cmd;
 736
 737	/* Allocate structure */
 738	vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
 739	if (vgadev == NULL) {
 740		vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
 741		/*
 742		 * What to do on allocation failure? For now, let's just do
 743		 * nothing, I'm not sure there is anything saner to be done.
 744		 */
 745		return false;
 746	}
 747
 748	/* Take lock & check for duplicates */
 749	spin_lock_irqsave(&vga_lock, flags);
 750	if (vgadev_find(pdev) != NULL) {
 751		BUG_ON(1);
 752		goto fail;
 753	}
 754	vgadev->pdev = pdev;
 755
 756	/* By default, assume we decode everything */
 757	vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
 758			  VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 759
 760	/* By default, mark it as decoding */
 761	vga_decode_count++;
 762
 763	/*
 764	 * Mark that we "own" resources based on our enables, we will
 765	 * clear that below if the bridge isn't forwarding.
 766	 */
 767	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
 768	if (cmd & PCI_COMMAND_IO)
 769		vgadev->owns |= VGA_RSRC_LEGACY_IO;
 770	if (cmd & PCI_COMMAND_MEMORY)
 771		vgadev->owns |= VGA_RSRC_LEGACY_MEM;
 772
 773	/* Check if VGA cycles can get down to us */
 774	bus = pdev->bus;
 775	while (bus) {
 776		bridge = bus->self;
 777		if (bridge) {
 778			u16 l;
 779
 780			pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l);
 781			if (!(l & PCI_BRIDGE_CTL_VGA)) {
 782				vgadev->owns = 0;
 783				break;
 784			}
 785		}
 786		bus = bus->parent;
 787	}
 788
 789	if (vga_is_boot_device(vgadev)) {
 790		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
 791			    vga_default_device() ?
 792			    " (overriding previous)" : "");
 793		vga_set_default_device(pdev);
 794	}
 795
 796	vga_arbiter_check_bridge_sharing(vgadev);
 797
 798	/* Add to the list */
 799	list_add_tail(&vgadev->list, &vga_list);
 800	vga_count++;
 801	vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
 802		vga_iostate_to_str(vgadev->decodes),
 803		vga_iostate_to_str(vgadev->owns),
 804		vga_iostate_to_str(vgadev->locks));
 805
 806	spin_unlock_irqrestore(&vga_lock, flags);
 807	return true;
 808fail:
 809	spin_unlock_irqrestore(&vga_lock, flags);
 810	kfree(vgadev);
 811	return false;
 812}
 813
 814static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
 815{
 816	struct vga_device *vgadev;
 817	unsigned long flags;
 818	bool ret = true;
 819
 820	spin_lock_irqsave(&vga_lock, flags);
 821	vgadev = vgadev_find(pdev);
 822	if (vgadev == NULL) {
 823		ret = false;
 824		goto bail;
 825	}
 826
 827	if (vga_default == pdev)
 828		vga_set_default_device(NULL);
 829
 830	if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
 831		vga_decode_count--;
 832
 833	/* Remove entry from list */
 834	list_del(&vgadev->list);
 835	vga_count--;
 836
 837	/* Wake up all possible waiters */
 838	wake_up_all(&vga_wait_queue);
 839bail:
 840	spin_unlock_irqrestore(&vga_lock, flags);
 841	kfree(vgadev);
 842	return ret;
 843}
 844
 845/* Called with the lock */
 846static void vga_update_device_decodes(struct vga_device *vgadev,
 847				      unsigned int new_decodes)
 848{
 849	struct device *dev = &vgadev->pdev->dev;
 850	unsigned int old_decodes = vgadev->decodes;
 851	unsigned int decodes_removed = ~new_decodes & old_decodes;
 852	unsigned int decodes_unlocked = vgadev->locks & decodes_removed;
 853
 854	vgadev->decodes = new_decodes;
 855
 856	vgaarb_info(dev, "VGA decodes changed: olddecodes=%s,decodes=%s:owns=%s\n",
 857		    vga_iostate_to_str(old_decodes),
 858		    vga_iostate_to_str(vgadev->decodes),
 859		    vga_iostate_to_str(vgadev->owns));
 860
 861	/* If we removed locked decodes, lock count goes to zero, and release */
 862	if (decodes_unlocked) {
 863		if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
 864			vgadev->io_lock_cnt = 0;
 865		if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
 866			vgadev->mem_lock_cnt = 0;
 867		__vga_put(vgadev, decodes_unlocked);
 868	}
 869
 870	/* Change decodes counter */
 871	if (old_decodes & VGA_RSRC_LEGACY_MASK &&
 872	    !(new_decodes & VGA_RSRC_LEGACY_MASK))
 873		vga_decode_count--;
 874	if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
 875	    new_decodes & VGA_RSRC_LEGACY_MASK)
 876		vga_decode_count++;
 877	vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
 878}
 879
 880static void __vga_set_legacy_decoding(struct pci_dev *pdev,
 881				      unsigned int decodes,
 882				      bool userspace)
 883{
 884	struct vga_device *vgadev;
 885	unsigned long flags;
 886
 887	decodes &= VGA_RSRC_LEGACY_MASK;
 888
 889	spin_lock_irqsave(&vga_lock, flags);
 890	vgadev = vgadev_find(pdev);
 891	if (vgadev == NULL)
 892		goto bail;
 893
 894	/* Don't let userspace futz with kernel driver decodes */
 895	if (userspace && vgadev->set_decode)
 896		goto bail;
 897
 898	/* Update the device decodes + counter */
 899	vga_update_device_decodes(vgadev, decodes);
 900
 901	/*
 902	 * XXX If somebody is going from "doesn't decode" to "decodes"
 903	 * state here, additional care must be taken as we may have pending
 904	 * ownership of non-legacy region.
 905	 */
 906bail:
 907	spin_unlock_irqrestore(&vga_lock, flags);
 908}
 909
 910/**
 911 * vga_set_legacy_decoding
 912 * @pdev: PCI device of the VGA card
 913 * @decodes: bit mask of what legacy regions the card decodes
 914 *
 915 * Indicate to the arbiter if the card decodes legacy VGA IOs, legacy VGA
 916 * Memory, both, or none. All cards default to both, the card driver (fbdev for
 917 * example) should tell the arbiter if it has disabled legacy decoding, so the
 918 * card can be left out of the arbitration process (and can be safe to take
 919 * interrupts at any time.
 920 */
 921void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
 922{
 923	__vga_set_legacy_decoding(pdev, decodes, false);
 924}
 925EXPORT_SYMBOL(vga_set_legacy_decoding);
 926
 927/**
 928 * vga_client_register - register or unregister a VGA arbitration client
 929 * @pdev: PCI device of the VGA client
 930 * @set_decode: VGA decode change callback
 931 *
 932 * Clients have two callback mechanisms they can use.
 933 *
 934 * @set_decode callback: If a client can disable its GPU VGA resource, it
 935 * will get a callback from this to set the encode/decode state.
 936 *
 937 * Rationale: we cannot disable VGA decode resources unconditionally
 938 * because some single GPU laptops seem to require ACPI or BIOS access to
 939 * the VGA registers to control things like backlights etc. Hopefully newer
 940 * multi-GPU laptops do something saner, and desktops won't have any
 941 * special ACPI for this. The driver will get a callback when VGA
 942 * arbitration is first used by userspace since some older X servers have
 943 * issues.
 944 *
 945 * Does not check whether a client for @pdev has been registered already.
 946 *
 947 * To unregister, call vga_client_unregister().
 948 *
 949 * Returns: 0 on success, -ENODEV on failure
 950 */
 951int vga_client_register(struct pci_dev *pdev,
 952		unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
 953{
 954	unsigned long flags;
 955	struct vga_device *vgadev;
 956
 957	spin_lock_irqsave(&vga_lock, flags);
 958	vgadev = vgadev_find(pdev);
 959	if (vgadev)
 960		vgadev->set_decode = set_decode;
 961	spin_unlock_irqrestore(&vga_lock, flags);
 962	if (!vgadev)
 963		return -ENODEV;
 964	return 0;
 965}
 966EXPORT_SYMBOL(vga_client_register);
 967
 968/*
 969 * Char driver implementation
 970 *
 971 * Semantics is:
 972 *
 973 *  open       : Open user instance of the arbiter. By default, it's
 974 *                attached to the default VGA device of the system.
 975 *
 976 *  close      : Close user instance, release locks
 977 *
 978 *  read       : Return a string indicating the status of the target.
 979 *                An IO state string is of the form {io,mem,io+mem,none},
 980 *                mc and ic are respectively mem and io lock counts (for
 981 *                debugging/diagnostic only). "decodes" indicate what the
 982 *                card currently decodes, "owns" indicates what is currently
 983 *                enabled on it, and "locks" indicates what is locked by this
 984 *                card. If the card is unplugged, we get "invalid" then for
 985 *                card_ID and an -ENODEV error is returned for any command
 986 *                until a new card is targeted
 987 *
 988 *   "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
 989 *
 990 * write       : write a command to the arbiter. List of commands is:
 991 *
 992 *   target <card_ID>   : switch target to card <card_ID> (see below)
 993 *   lock <io_state>    : acquire locks on target ("none" is invalid io_state)
 994 *   trylock <io_state> : non-blocking acquire locks on target
 995 *   unlock <io_state>  : release locks on target
 996 *   unlock all         : release all locks on target held by this user
 997 *   decodes <io_state> : set the legacy decoding attributes for the card
 998 *
 999 * poll         : event if something change on any card (not just the target)
1000 *
1001 * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
1002 * to go back to the system default card (TODO: not implemented yet).
1003 * Currently, only PCI is supported as a prefix, but the userland API may
1004 * support other bus types in the future, even if the current kernel
1005 * implementation doesn't.
1006 *
1007 * Note about locks:
1008 *
1009 * The driver keeps track of which user has what locks on which card. It
1010 * supports stacking, like the kernel one. This complicates the implementation
1011 * a bit, but makes the arbiter more tolerant to userspace problems and able
1012 * to properly cleanup in all cases when a process dies.
1013 * Currently, a max of 16 cards simultaneously can have locks issued from
1014 * userspace for a given user (file descriptor instance) of the arbiter.
1015 *
1016 * If the device is hot-unplugged, there is a hook inside the module to notify
1017 * it being added/removed in the system and automatically added/removed in
1018 * the arbiter.
1019 */
1020
1021#define MAX_USER_CARDS         CONFIG_VGA_ARB_MAX_GPUS
1022#define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
1023
1024/* Each user has an array of these, tracking which cards have locks */
1025struct vga_arb_user_card {
1026	struct pci_dev *pdev;
1027	unsigned int mem_cnt;
1028	unsigned int io_cnt;
1029};
1030
1031struct vga_arb_private {
1032	struct list_head list;
1033	struct pci_dev *target;
1034	struct vga_arb_user_card cards[MAX_USER_CARDS];
1035	spinlock_t lock;
1036};
1037
1038static LIST_HEAD(vga_user_list);
1039static DEFINE_SPINLOCK(vga_user_lock);
1040
1041
1042/*
1043 * Take a string in the format: "PCI:domain:bus:dev.fn" and return the
1044 * respective values. If the string is not in this format, return 0.
1045 */
1046static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
1047			       unsigned int *bus, unsigned int *devfn)
1048{
1049	int n;
1050	unsigned int slot, func;
1051
1052	n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
1053	if (n != 4)
1054		return 0;
1055
1056	*devfn = PCI_DEVFN(slot, func);
1057
1058	return 1;
1059}
1060
1061static ssize_t vga_arb_read(struct file *file, char __user *buf,
1062			    size_t count, loff_t *ppos)
1063{
1064	struct vga_arb_private *priv = file->private_data;
1065	struct vga_device *vgadev;
1066	struct pci_dev *pdev;
1067	unsigned long flags;
1068	size_t len;
1069	int rc;
1070	char *lbuf;
1071
1072	lbuf = kmalloc(1024, GFP_KERNEL);
1073	if (lbuf == NULL)
1074		return -ENOMEM;
1075
1076	/* Protect vga_list */
1077	spin_lock_irqsave(&vga_lock, flags);
1078
1079	/* If we are targeting the default, use it */
1080	pdev = priv->target;
1081	if (pdev == NULL || pdev == PCI_INVALID_CARD) {
1082		spin_unlock_irqrestore(&vga_lock, flags);
1083		len = sprintf(lbuf, "invalid");
1084		goto done;
1085	}
1086
1087	/* Find card vgadev structure */
1088	vgadev = vgadev_find(pdev);
1089	if (vgadev == NULL) {
1090		/*
1091		 * Wow, it's not in the list, that shouldn't happen, let's
1092		 * fix us up and return invalid card.
1093		 */
1094		spin_unlock_irqrestore(&vga_lock, flags);
1095		len = sprintf(lbuf, "invalid");
1096		goto done;
1097	}
1098
1099	/* Fill the buffer with info */
1100	len = snprintf(lbuf, 1024,
1101		       "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%u:%u)\n",
1102		       vga_decode_count, pci_name(pdev),
1103		       vga_iostate_to_str(vgadev->decodes),
1104		       vga_iostate_to_str(vgadev->owns),
1105		       vga_iostate_to_str(vgadev->locks),
1106		       vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
1107
1108	spin_unlock_irqrestore(&vga_lock, flags);
1109done:
1110
1111	/* Copy that to user */
1112	if (len > count)
1113		len = count;
1114	rc = copy_to_user(buf, lbuf, len);
1115	kfree(lbuf);
1116	if (rc)
1117		return -EFAULT;
1118	return len;
1119}
1120
1121/*
1122 * TODO: To avoid parsing inside kernel and to improve the speed we may
1123 * consider use ioctl here
1124 */
1125static ssize_t vga_arb_write(struct file *file, const char __user *buf,
1126			     size_t count, loff_t *ppos)
1127{
1128	struct vga_arb_private *priv = file->private_data;
1129	struct vga_arb_user_card *uc = NULL;
1130	struct pci_dev *pdev;
1131
1132	unsigned int io_state;
1133
1134	char kbuf[64], *curr_pos;
1135	size_t remaining = count;
1136
1137	int ret_val;
1138	int i;
1139
1140	if (count >= sizeof(kbuf))
1141		return -EINVAL;
1142	if (copy_from_user(kbuf, buf, count))
1143		return -EFAULT;
1144	curr_pos = kbuf;
1145	kbuf[count] = '\0';
1146
1147	if (strncmp(curr_pos, "lock ", 5) == 0) {
1148		curr_pos += 5;
1149		remaining -= 5;
1150
1151		pr_debug("client 0x%p called 'lock'\n", priv);
1152
1153		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1154			ret_val = -EPROTO;
1155			goto done;
1156		}
1157		if (io_state == VGA_RSRC_NONE) {
1158			ret_val = -EPROTO;
1159			goto done;
1160		}
1161
1162		pdev = priv->target;
1163		if (priv->target == NULL) {
1164			ret_val = -ENODEV;
1165			goto done;
1166		}
1167
1168		vga_get_uninterruptible(pdev, io_state);
1169
1170		/* Update the client's locks lists */
1171		for (i = 0; i < MAX_USER_CARDS; i++) {
1172			if (priv->cards[i].pdev == pdev) {
1173				if (io_state & VGA_RSRC_LEGACY_IO)
1174					priv->cards[i].io_cnt++;
1175				if (io_state & VGA_RSRC_LEGACY_MEM)
1176					priv->cards[i].mem_cnt++;
1177				break;
1178			}
1179		}
1180
1181		ret_val = count;
1182		goto done;
1183	} else if (strncmp(curr_pos, "unlock ", 7) == 0) {
1184		curr_pos += 7;
1185		remaining -= 7;
1186
1187		pr_debug("client 0x%p called 'unlock'\n", priv);
1188
1189		if (strncmp(curr_pos, "all", 3) == 0)
1190			io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
1191		else {
1192			if (!vga_str_to_iostate
1193			    (curr_pos, remaining, &io_state)) {
1194				ret_val = -EPROTO;
1195				goto done;
1196			}
1197			/* TODO: Add this?
1198			   if (io_state == VGA_RSRC_NONE) {
1199			   ret_val = -EPROTO;
1200			   goto done;
1201			   }
1202			  */
1203		}
1204
1205		pdev = priv->target;
1206		if (priv->target == NULL) {
1207			ret_val = -ENODEV;
1208			goto done;
1209		}
1210		for (i = 0; i < MAX_USER_CARDS; i++) {
1211			if (priv->cards[i].pdev == pdev)
1212				uc = &priv->cards[i];
1213		}
1214
1215		if (!uc) {
1216			ret_val = -EINVAL;
1217			goto done;
1218		}
1219
1220		if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {
1221			ret_val = -EINVAL;
1222			goto done;
1223		}
1224
1225		if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {
1226			ret_val = -EINVAL;
1227			goto done;
1228		}
1229
1230		vga_put(pdev, io_state);
1231
1232		if (io_state & VGA_RSRC_LEGACY_IO)
1233			uc->io_cnt--;
1234		if (io_state & VGA_RSRC_LEGACY_MEM)
1235			uc->mem_cnt--;
1236
1237		ret_val = count;
1238		goto done;
1239	} else if (strncmp(curr_pos, "trylock ", 8) == 0) {
1240		curr_pos += 8;
1241		remaining -= 8;
1242
1243		pr_debug("client 0x%p called 'trylock'\n", priv);
1244
1245		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1246			ret_val = -EPROTO;
1247			goto done;
1248		}
1249		/* TODO: Add this?
1250		   if (io_state == VGA_RSRC_NONE) {
1251		   ret_val = -EPROTO;
1252		   goto done;
1253		   }
1254		 */
1255
1256		pdev = priv->target;
1257		if (priv->target == NULL) {
1258			ret_val = -ENODEV;
1259			goto done;
1260		}
1261
1262		if (vga_tryget(pdev, io_state)) {
1263			/* Update the client's locks lists... */
1264			for (i = 0; i < MAX_USER_CARDS; i++) {
1265				if (priv->cards[i].pdev == pdev) {
1266					if (io_state & VGA_RSRC_LEGACY_IO)
1267						priv->cards[i].io_cnt++;
1268					if (io_state & VGA_RSRC_LEGACY_MEM)
1269						priv->cards[i].mem_cnt++;
1270					break;
1271				}
1272			}
1273			ret_val = count;
1274			goto done;
1275		} else {
1276			ret_val = -EBUSY;
1277			goto done;
1278		}
1279
1280	} else if (strncmp(curr_pos, "target ", 7) == 0) {
1281		unsigned int domain, bus, devfn;
1282		struct vga_device *vgadev;
1283
1284		curr_pos += 7;
1285		remaining -= 7;
1286		pr_debug("client 0x%p called 'target'\n", priv);
1287		/* If target is default */
1288		if (!strncmp(curr_pos, "default", 7))
1289			pdev = pci_dev_get(vga_default_device());
1290		else {
1291			if (!vga_pci_str_to_vars(curr_pos, remaining,
1292						 &domain, &bus, &devfn)) {
1293				ret_val = -EPROTO;
1294				goto done;
1295			}
1296			pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
1297			if (!pdev) {
1298				pr_debug("invalid PCI address %04x:%02x:%02x.%x\n",
1299					 domain, bus, PCI_SLOT(devfn),
1300					 PCI_FUNC(devfn));
1301				ret_val = -ENODEV;
1302				goto done;
1303			}
1304
1305			pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos,
1306				domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
1307				pdev);
1308		}
1309
1310		vgadev = vgadev_find(pdev);
1311		pr_debug("vgadev %p\n", vgadev);
1312		if (vgadev == NULL) {
1313			if (pdev) {
1314				vgaarb_dbg(&pdev->dev, "not a VGA device\n");
1315				pci_dev_put(pdev);
1316			}
1317
1318			ret_val = -ENODEV;
1319			goto done;
1320		}
1321
1322		priv->target = pdev;
1323		for (i = 0; i < MAX_USER_CARDS; i++) {
1324			if (priv->cards[i].pdev == pdev)
1325				break;
1326			if (priv->cards[i].pdev == NULL) {
1327				priv->cards[i].pdev = pdev;
1328				priv->cards[i].io_cnt = 0;
1329				priv->cards[i].mem_cnt = 0;
1330				break;
1331			}
1332		}
1333		if (i == MAX_USER_CARDS) {
1334			vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",
1335				MAX_USER_CARDS);
1336			pci_dev_put(pdev);
1337			/* XXX: Which value to return? */
1338			ret_val =  -ENOMEM;
1339			goto done;
1340		}
1341
1342		ret_val = count;
1343		pci_dev_put(pdev);
1344		goto done;
1345
1346
1347	} else if (strncmp(curr_pos, "decodes ", 8) == 0) {
1348		curr_pos += 8;
1349		remaining -= 8;
1350		pr_debug("client 0x%p called 'decodes'\n", priv);
1351
1352		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1353			ret_val = -EPROTO;
1354			goto done;
1355		}
1356		pdev = priv->target;
1357		if (priv->target == NULL) {
1358			ret_val = -ENODEV;
1359			goto done;
1360		}
1361
1362		__vga_set_legacy_decoding(pdev, io_state, true);
1363		ret_val = count;
1364		goto done;
1365	}
1366	/* If we got here, the message written is not part of the protocol! */
1367	return -EPROTO;
1368
1369done:
1370	return ret_val;
1371}
1372
1373static __poll_t vga_arb_fpoll(struct file *file, poll_table *wait)
1374{
1375	pr_debug("%s\n", __func__);
1376
1377	poll_wait(file, &vga_wait_queue, wait);
1378	return EPOLLIN;
1379}
1380
1381static int vga_arb_open(struct inode *inode, struct file *file)
1382{
1383	struct vga_arb_private *priv;
1384	unsigned long flags;
1385
1386	pr_debug("%s\n", __func__);
1387
1388	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1389	if (priv == NULL)
1390		return -ENOMEM;
1391	spin_lock_init(&priv->lock);
1392	file->private_data = priv;
1393
1394	spin_lock_irqsave(&vga_user_lock, flags);
1395	list_add(&priv->list, &vga_user_list);
1396	spin_unlock_irqrestore(&vga_user_lock, flags);
1397
1398	/* Set the client's lists of locks */
1399	priv->target = vga_default_device(); /* Maybe this is still null! */
1400	priv->cards[0].pdev = priv->target;
1401	priv->cards[0].io_cnt = 0;
1402	priv->cards[0].mem_cnt = 0;
1403
1404	return 0;
1405}
1406
1407static int vga_arb_release(struct inode *inode, struct file *file)
1408{
1409	struct vga_arb_private *priv = file->private_data;
1410	struct vga_arb_user_card *uc;
1411	unsigned long flags;
1412	int i;
1413
1414	pr_debug("%s\n", __func__);
1415
1416	spin_lock_irqsave(&vga_user_lock, flags);
1417	list_del(&priv->list);
1418	for (i = 0; i < MAX_USER_CARDS; i++) {
1419		uc = &priv->cards[i];
1420		if (uc->pdev == NULL)
1421			continue;
1422		vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",
1423			uc->io_cnt, uc->mem_cnt);
1424		while (uc->io_cnt--)
1425			vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
1426		while (uc->mem_cnt--)
1427			vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
1428	}
1429	spin_unlock_irqrestore(&vga_user_lock, flags);
1430
1431	kfree(priv);
1432
1433	return 0;
1434}
1435
1436/*
1437 * Callback any registered clients to let them know we have a change in VGA
1438 * cards.
1439 */
1440static void vga_arbiter_notify_clients(void)
1441{
1442	struct vga_device *vgadev;
1443	unsigned long flags;
1444	unsigned int new_decodes;
1445	bool new_state;
1446
1447	if (!vga_arbiter_used)
1448		return;
1449
1450	new_state = (vga_count > 1) ? false : true;
1451
1452	spin_lock_irqsave(&vga_lock, flags);
1453	list_for_each_entry(vgadev, &vga_list, list) {
1454		if (vgadev->set_decode) {
1455			new_decodes = vgadev->set_decode(vgadev->pdev,
1456							 new_state);
1457			vga_update_device_decodes(vgadev, new_decodes);
1458		}
1459	}
1460	spin_unlock_irqrestore(&vga_lock, flags);
1461}
1462
1463static int pci_notify(struct notifier_block *nb, unsigned long action,
1464		      void *data)
1465{
1466	struct device *dev = data;
1467	struct pci_dev *pdev = to_pci_dev(dev);
1468	bool notify = false;
1469
1470	vgaarb_dbg(dev, "%s\n", __func__);
1471
1472	/* Only deal with VGA class devices */
1473	if (!pci_is_vga(pdev))
1474		return 0;
1475
1476	/*
1477	 * For now, we're only interested in devices added and removed.
1478	 * I didn't test this thing here, so someone needs to double check
1479	 * for the cases of hot-pluggable VGA cards.
1480	 */
1481	if (action == BUS_NOTIFY_ADD_DEVICE)
1482		notify = vga_arbiter_add_pci_device(pdev);
1483	else if (action == BUS_NOTIFY_DEL_DEVICE)
1484		notify = vga_arbiter_del_pci_device(pdev);
1485
1486	if (notify)
1487		vga_arbiter_notify_clients();
1488	return 0;
1489}
1490
1491static struct notifier_block pci_notifier = {
1492	.notifier_call = pci_notify,
1493};
1494
1495static const struct file_operations vga_arb_device_fops = {
1496	.read = vga_arb_read,
1497	.write = vga_arb_write,
1498	.poll = vga_arb_fpoll,
1499	.open = vga_arb_open,
1500	.release = vga_arb_release,
1501	.llseek = noop_llseek,
1502};
1503
1504static struct miscdevice vga_arb_device = {
1505	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
1506};
1507
1508static int __init vga_arb_device_init(void)
1509{
1510	int rc;
1511	struct pci_dev *pdev;
1512
1513	rc = misc_register(&vga_arb_device);
1514	if (rc < 0)
1515		pr_err("error %d registering device\n", rc);
1516
1517	bus_register_notifier(&pci_bus_type, &pci_notifier);
1518
1519	/* Add all VGA class PCI devices by default */
1520	pdev = NULL;
1521	while ((pdev =
1522		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
1523			       PCI_ANY_ID, pdev)) != NULL) {
1524		if (pci_is_vga(pdev))
1525			vga_arbiter_add_pci_device(pdev);
1526	}
1527
1528	pr_info("loaded\n");
1529	return rc;
1530}
1531subsys_initcall_sync(vga_arb_device_init);