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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 u64 base = screen_info.lfb_base;
561 u64 size = screen_info.lfb_size;
562 struct resource *r;
563 u64 limit;
564
565 /* Select the device owning the boot framebuffer if there is one */
566
567 if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
568 base |= (u64)screen_info.ext_lfb_base << 32;
569
570 limit = base + size;
571
572 /* Does firmware framebuffer belong to us? */
573 pci_dev_for_each_resource(pdev, r) {
574 if (resource_type(r) != IORESOURCE_MEM)
575 continue;
576
577 if (!r->start || !r->end)
578 continue;
579
580 if (base < r->start || limit >= r->end)
581 continue;
582
583 return true;
584 }
585#endif
586 return false;
587}
588
589static bool vga_arb_integrated_gpu(struct device *dev)
590{
591#if defined(CONFIG_ACPI)
592 struct acpi_device *adev = ACPI_COMPANION(dev);
593
594 return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);
595#else
596 return false;
597#endif
598}
599
600/*
601 * Return true if vgadev is a better default VGA device than the best one
602 * we've seen so far.
603 */
604static bool vga_is_boot_device(struct vga_device *vgadev)
605{
606 struct vga_device *boot_vga = vgadev_find(vga_default_device());
607 struct pci_dev *pdev = vgadev->pdev;
608 u16 cmd, boot_cmd;
609
610 /*
611 * We select the default VGA device in this order:
612 * Firmware framebuffer (see vga_arb_select_default_device())
613 * Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)
614 * Non-legacy integrated device (see vga_arb_select_default_device())
615 * Non-legacy discrete device (see vga_arb_select_default_device())
616 * Other device (see vga_arb_select_default_device())
617 */
618
619 /*
620 * We always prefer a firmware default device, so if we've already
621 * found one, there's no need to consider vgadev.
622 */
623 if (boot_vga && boot_vga->is_firmware_default)
624 return false;
625
626 if (vga_is_firmware_default(pdev)) {
627 vgadev->is_firmware_default = true;
628 return true;
629 }
630
631 /*
632 * A legacy VGA device has MEM and IO enabled and any bridges
633 * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy
634 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are
635 * routed to it.
636 *
637 * We use the first one we find, so if we've already found one,
638 * vgadev is no better.
639 */
640 if (boot_vga &&
641 (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
642 return false;
643
644 if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
645 return true;
646
647 /*
648 * If we haven't found a legacy VGA device, accept a non-legacy
649 * device. It may have either IO or MEM enabled, and bridges may
650 * not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to
651 * use legacy VGA resources. Prefer an integrated GPU over others.
652 */
653 pci_read_config_word(pdev, PCI_COMMAND, &cmd);
654 if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
655
656 /*
657 * An integrated GPU overrides a previous non-legacy
658 * device. We expect only a single integrated GPU, but if
659 * there are more, we use the *last* because that was the
660 * previous behavior.
661 */
662 if (vga_arb_integrated_gpu(&pdev->dev))
663 return true;
664
665 /*
666 * We prefer the first non-legacy discrete device we find.
667 * If we already found one, vgadev is no better.
668 */
669 if (boot_vga) {
670 pci_read_config_word(boot_vga->pdev, PCI_COMMAND,
671 &boot_cmd);
672 if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
673 return false;
674 }
675 return true;
676 }
677
678 /*
679 * Vgadev has neither IO nor MEM enabled. If we haven't found any
680 * other VGA devices, it is the best candidate so far.
681 */
682 if (!boot_vga)
683 return true;
684
685 return false;
686}
687
688/*
689 * Rules for using a bridge to control a VGA descendant decoding: if a bridge
690 * has only one VGA descendant then it can be used to control the VGA routing
691 * for that device. It should always use the bridge closest to the device to
692 * control it. If a bridge has a direct VGA descendant, but also have a sub-
693 * bridge VGA descendant then we cannot use that bridge to control the direct
694 * VGA descendant. So for every device we register, we need to iterate all
695 * its parent bridges so we can invalidate any devices using them properly.
696 */
697static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
698{
699 struct vga_device *same_bridge_vgadev;
700 struct pci_bus *new_bus, *bus;
701 struct pci_dev *new_bridge, *bridge;
702
703 vgadev->bridge_has_one_vga = true;
704
705 if (list_empty(&vga_list)) {
706 vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
707 return;
708 }
709
710 /* Iterate the new device's bridge hierarchy */
711 new_bus = vgadev->pdev->bus;
712 while (new_bus) {
713 new_bridge = new_bus->self;
714
715 /* Go through list of devices already registered */
716 list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
717 bus = same_bridge_vgadev->pdev->bus;
718 bridge = bus->self;
719
720 /* See if it shares a bridge with this device */
721 if (new_bridge == bridge) {
722 /*
723 * If its direct parent bridge is the same
724 * as any bridge of this device then it can't
725 * be used for that device.
726 */
727 same_bridge_vgadev->bridge_has_one_vga = false;
728 }
729
730 /*
731 * Now iterate the previous device's bridge hierarchy.
732 * If the new device's parent bridge is in the other
733 * device's hierarchy, we can't use it to control this
734 * device.
735 */
736 while (bus) {
737 bridge = bus->self;
738
739 if (bridge && bridge == vgadev->pdev->bus->self)
740 vgadev->bridge_has_one_vga = false;
741
742 bus = bus->parent;
743 }
744 }
745 new_bus = new_bus->parent;
746 }
747
748 if (vgadev->bridge_has_one_vga)
749 vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
750 else
751 vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
752}
753
754/*
755 * Currently, we assume that the "initial" setup of the system is not sane,
756 * that is, we come up with conflicting devices and let the arbiter's
757 * client decide if devices decodes legacy things or not.
758 */
759static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
760{
761 struct vga_device *vgadev;
762 unsigned long flags;
763 struct pci_bus *bus;
764 struct pci_dev *bridge;
765 u16 cmd;
766
767 /* Allocate structure */
768 vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
769 if (vgadev == NULL) {
770 vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
771 /*
772 * What to do on allocation failure? For now, let's just do
773 * nothing, I'm not sure there is anything saner to be done.
774 */
775 return false;
776 }
777
778 /* Take lock & check for duplicates */
779 spin_lock_irqsave(&vga_lock, flags);
780 if (vgadev_find(pdev) != NULL) {
781 BUG_ON(1);
782 goto fail;
783 }
784 vgadev->pdev = pdev;
785
786 /* By default, assume we decode everything */
787 vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
788 VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
789
790 /* By default, mark it as decoding */
791 vga_decode_count++;
792
793 /*
794 * Mark that we "own" resources based on our enables, we will
795 * clear that below if the bridge isn't forwarding.
796 */
797 pci_read_config_word(pdev, PCI_COMMAND, &cmd);
798 if (cmd & PCI_COMMAND_IO)
799 vgadev->owns |= VGA_RSRC_LEGACY_IO;
800 if (cmd & PCI_COMMAND_MEMORY)
801 vgadev->owns |= VGA_RSRC_LEGACY_MEM;
802
803 /* Check if VGA cycles can get down to us */
804 bus = pdev->bus;
805 while (bus) {
806 bridge = bus->self;
807 if (bridge) {
808 u16 l;
809
810 pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l);
811 if (!(l & PCI_BRIDGE_CTL_VGA)) {
812 vgadev->owns = 0;
813 break;
814 }
815 }
816 bus = bus->parent;
817 }
818
819 if (vga_is_boot_device(vgadev)) {
820 vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
821 vga_default_device() ?
822 " (overriding previous)" : "");
823 vga_set_default_device(pdev);
824 }
825
826 vga_arbiter_check_bridge_sharing(vgadev);
827
828 /* Add to the list */
829 list_add_tail(&vgadev->list, &vga_list);
830 vga_count++;
831 vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
832 vga_iostate_to_str(vgadev->decodes),
833 vga_iostate_to_str(vgadev->owns),
834 vga_iostate_to_str(vgadev->locks));
835
836 spin_unlock_irqrestore(&vga_lock, flags);
837 return true;
838fail:
839 spin_unlock_irqrestore(&vga_lock, flags);
840 kfree(vgadev);
841 return false;
842}
843
844static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
845{
846 struct vga_device *vgadev;
847 unsigned long flags;
848 bool ret = true;
849
850 spin_lock_irqsave(&vga_lock, flags);
851 vgadev = vgadev_find(pdev);
852 if (vgadev == NULL) {
853 ret = false;
854 goto bail;
855 }
856
857 if (vga_default == pdev)
858 vga_set_default_device(NULL);
859
860 if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
861 vga_decode_count--;
862
863 /* Remove entry from list */
864 list_del(&vgadev->list);
865 vga_count--;
866
867 /* Wake up all possible waiters */
868 wake_up_all(&vga_wait_queue);
869bail:
870 spin_unlock_irqrestore(&vga_lock, flags);
871 kfree(vgadev);
872 return ret;
873}
874
875/* Called with the lock */
876static void vga_update_device_decodes(struct vga_device *vgadev,
877 unsigned int new_decodes)
878{
879 struct device *dev = &vgadev->pdev->dev;
880 unsigned int old_decodes = vgadev->decodes;
881 unsigned int decodes_removed = ~new_decodes & old_decodes;
882 unsigned int decodes_unlocked = vgadev->locks & decodes_removed;
883
884 vgadev->decodes = new_decodes;
885
886 vgaarb_info(dev, "VGA decodes changed: olddecodes=%s,decodes=%s:owns=%s\n",
887 vga_iostate_to_str(old_decodes),
888 vga_iostate_to_str(vgadev->decodes),
889 vga_iostate_to_str(vgadev->owns));
890
891 /* If we removed locked decodes, lock count goes to zero, and release */
892 if (decodes_unlocked) {
893 if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
894 vgadev->io_lock_cnt = 0;
895 if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
896 vgadev->mem_lock_cnt = 0;
897 __vga_put(vgadev, decodes_unlocked);
898 }
899
900 /* Change decodes counter */
901 if (old_decodes & VGA_RSRC_LEGACY_MASK &&
902 !(new_decodes & VGA_RSRC_LEGACY_MASK))
903 vga_decode_count--;
904 if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
905 new_decodes & VGA_RSRC_LEGACY_MASK)
906 vga_decode_count++;
907 vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
908}
909
910static void __vga_set_legacy_decoding(struct pci_dev *pdev,
911 unsigned int decodes,
912 bool userspace)
913{
914 struct vga_device *vgadev;
915 unsigned long flags;
916
917 decodes &= VGA_RSRC_LEGACY_MASK;
918
919 spin_lock_irqsave(&vga_lock, flags);
920 vgadev = vgadev_find(pdev);
921 if (vgadev == NULL)
922 goto bail;
923
924 /* Don't let userspace futz with kernel driver decodes */
925 if (userspace && vgadev->set_decode)
926 goto bail;
927
928 /* Update the device decodes + counter */
929 vga_update_device_decodes(vgadev, decodes);
930
931 /*
932 * XXX If somebody is going from "doesn't decode" to "decodes"
933 * state here, additional care must be taken as we may have pending
934 * ownership of non-legacy region.
935 */
936bail:
937 spin_unlock_irqrestore(&vga_lock, flags);
938}
939
940/**
941 * vga_set_legacy_decoding
942 * @pdev: PCI device of the VGA card
943 * @decodes: bit mask of what legacy regions the card decodes
944 *
945 * Indicate to the arbiter if the card decodes legacy VGA IOs, legacy VGA
946 * Memory, both, or none. All cards default to both, the card driver (fbdev for
947 * example) should tell the arbiter if it has disabled legacy decoding, so the
948 * card can be left out of the arbitration process (and can be safe to take
949 * interrupts at any time.
950 */
951void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
952{
953 __vga_set_legacy_decoding(pdev, decodes, false);
954}
955EXPORT_SYMBOL(vga_set_legacy_decoding);
956
957/**
958 * vga_client_register - register or unregister a VGA arbitration client
959 * @pdev: PCI device of the VGA client
960 * @set_decode: VGA decode change callback
961 *
962 * Clients have two callback mechanisms they can use.
963 *
964 * @set_decode callback: If a client can disable its GPU VGA resource, it
965 * will get a callback from this to set the encode/decode state.
966 *
967 * Rationale: we cannot disable VGA decode resources unconditionally
968 * because some single GPU laptops seem to require ACPI or BIOS access to
969 * the VGA registers to control things like backlights etc. Hopefully newer
970 * multi-GPU laptops do something saner, and desktops won't have any
971 * special ACPI for this. The driver will get a callback when VGA
972 * arbitration is first used by userspace since some older X servers have
973 * issues.
974 *
975 * Does not check whether a client for @pdev has been registered already.
976 *
977 * To unregister, call vga_client_unregister().
978 *
979 * Returns: 0 on success, -ENODEV on failure
980 */
981int vga_client_register(struct pci_dev *pdev,
982 unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
983{
984 unsigned long flags;
985 struct vga_device *vgadev;
986
987 spin_lock_irqsave(&vga_lock, flags);
988 vgadev = vgadev_find(pdev);
989 if (vgadev)
990 vgadev->set_decode = set_decode;
991 spin_unlock_irqrestore(&vga_lock, flags);
992 if (!vgadev)
993 return -ENODEV;
994 return 0;
995}
996EXPORT_SYMBOL(vga_client_register);
997
998/*
999 * Char driver implementation
1000 *
1001 * Semantics is:
1002 *
1003 * open : Open user instance of the arbiter. By default, it's
1004 * attached to the default VGA device of the system.
1005 *
1006 * close : Close user instance, release locks
1007 *
1008 * read : Return a string indicating the status of the target.
1009 * An IO state string is of the form {io,mem,io+mem,none},
1010 * mc and ic are respectively mem and io lock counts (for
1011 * debugging/diagnostic only). "decodes" indicate what the
1012 * card currently decodes, "owns" indicates what is currently
1013 * enabled on it, and "locks" indicates what is locked by this
1014 * card. If the card is unplugged, we get "invalid" then for
1015 * card_ID and an -ENODEV error is returned for any command
1016 * until a new card is targeted
1017 *
1018 * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
1019 *
1020 * write : write a command to the arbiter. List of commands is:
1021 *
1022 * target <card_ID> : switch target to card <card_ID> (see below)
1023 * lock <io_state> : acquire locks on target ("none" is invalid io_state)
1024 * trylock <io_state> : non-blocking acquire locks on target
1025 * unlock <io_state> : release locks on target
1026 * unlock all : release all locks on target held by this user
1027 * decodes <io_state> : set the legacy decoding attributes for the card
1028 *
1029 * poll : event if something change on any card (not just the target)
1030 *
1031 * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
1032 * to go back to the system default card (TODO: not implemented yet).
1033 * Currently, only PCI is supported as a prefix, but the userland API may
1034 * support other bus types in the future, even if the current kernel
1035 * implementation doesn't.
1036 *
1037 * Note about locks:
1038 *
1039 * The driver keeps track of which user has what locks on which card. It
1040 * supports stacking, like the kernel one. This complicates the implementation
1041 * a bit, but makes the arbiter more tolerant to userspace problems and able
1042 * to properly cleanup in all cases when a process dies.
1043 * Currently, a max of 16 cards simultaneously can have locks issued from
1044 * userspace for a given user (file descriptor instance) of the arbiter.
1045 *
1046 * If the device is hot-unplugged, there is a hook inside the module to notify
1047 * it being added/removed in the system and automatically added/removed in
1048 * the arbiter.
1049 */
1050
1051#define MAX_USER_CARDS CONFIG_VGA_ARB_MAX_GPUS
1052#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
1053
1054/* Each user has an array of these, tracking which cards have locks */
1055struct vga_arb_user_card {
1056 struct pci_dev *pdev;
1057 unsigned int mem_cnt;
1058 unsigned int io_cnt;
1059};
1060
1061struct vga_arb_private {
1062 struct list_head list;
1063 struct pci_dev *target;
1064 struct vga_arb_user_card cards[MAX_USER_CARDS];
1065 spinlock_t lock;
1066};
1067
1068static LIST_HEAD(vga_user_list);
1069static DEFINE_SPINLOCK(vga_user_lock);
1070
1071
1072/*
1073 * Take a string in the format: "PCI:domain:bus:dev.fn" and return the
1074 * respective values. If the string is not in this format, return 0.
1075 */
1076static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
1077 unsigned int *bus, unsigned int *devfn)
1078{
1079 int n;
1080 unsigned int slot, func;
1081
1082 n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
1083 if (n != 4)
1084 return 0;
1085
1086 *devfn = PCI_DEVFN(slot, func);
1087
1088 return 1;
1089}
1090
1091static ssize_t vga_arb_read(struct file *file, char __user *buf,
1092 size_t count, loff_t *ppos)
1093{
1094 struct vga_arb_private *priv = file->private_data;
1095 struct vga_device *vgadev;
1096 struct pci_dev *pdev;
1097 unsigned long flags;
1098 size_t len;
1099 int rc;
1100 char *lbuf;
1101
1102 lbuf = kmalloc(1024, GFP_KERNEL);
1103 if (lbuf == NULL)
1104 return -ENOMEM;
1105
1106 /* Protect vga_list */
1107 spin_lock_irqsave(&vga_lock, flags);
1108
1109 /* If we are targeting the default, use it */
1110 pdev = priv->target;
1111 if (pdev == NULL || pdev == PCI_INVALID_CARD) {
1112 spin_unlock_irqrestore(&vga_lock, flags);
1113 len = sprintf(lbuf, "invalid");
1114 goto done;
1115 }
1116
1117 /* Find card vgadev structure */
1118 vgadev = vgadev_find(pdev);
1119 if (vgadev == NULL) {
1120 /*
1121 * Wow, it's not in the list, that shouldn't happen, let's
1122 * fix us up and return invalid card.
1123 */
1124 spin_unlock_irqrestore(&vga_lock, flags);
1125 len = sprintf(lbuf, "invalid");
1126 goto done;
1127 }
1128
1129 /* Fill the buffer with info */
1130 len = snprintf(lbuf, 1024,
1131 "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%u:%u)\n",
1132 vga_decode_count, pci_name(pdev),
1133 vga_iostate_to_str(vgadev->decodes),
1134 vga_iostate_to_str(vgadev->owns),
1135 vga_iostate_to_str(vgadev->locks),
1136 vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
1137
1138 spin_unlock_irqrestore(&vga_lock, flags);
1139done:
1140
1141 /* Copy that to user */
1142 if (len > count)
1143 len = count;
1144 rc = copy_to_user(buf, lbuf, len);
1145 kfree(lbuf);
1146 if (rc)
1147 return -EFAULT;
1148 return len;
1149}
1150
1151/*
1152 * TODO: To avoid parsing inside kernel and to improve the speed we may
1153 * consider use ioctl here
1154 */
1155static ssize_t vga_arb_write(struct file *file, const char __user *buf,
1156 size_t count, loff_t *ppos)
1157{
1158 struct vga_arb_private *priv = file->private_data;
1159 struct vga_arb_user_card *uc = NULL;
1160 struct pci_dev *pdev;
1161
1162 unsigned int io_state;
1163
1164 char kbuf[64], *curr_pos;
1165 size_t remaining = count;
1166
1167 int ret_val;
1168 int i;
1169
1170 if (count >= sizeof(kbuf))
1171 return -EINVAL;
1172 if (copy_from_user(kbuf, buf, count))
1173 return -EFAULT;
1174 curr_pos = kbuf;
1175 kbuf[count] = '\0';
1176
1177 if (strncmp(curr_pos, "lock ", 5) == 0) {
1178 curr_pos += 5;
1179 remaining -= 5;
1180
1181 pr_debug("client 0x%p called 'lock'\n", priv);
1182
1183 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1184 ret_val = -EPROTO;
1185 goto done;
1186 }
1187 if (io_state == VGA_RSRC_NONE) {
1188 ret_val = -EPROTO;
1189 goto done;
1190 }
1191
1192 pdev = priv->target;
1193 if (priv->target == NULL) {
1194 ret_val = -ENODEV;
1195 goto done;
1196 }
1197
1198 vga_get_uninterruptible(pdev, io_state);
1199
1200 /* Update the client's locks lists */
1201 for (i = 0; i < MAX_USER_CARDS; i++) {
1202 if (priv->cards[i].pdev == pdev) {
1203 if (io_state & VGA_RSRC_LEGACY_IO)
1204 priv->cards[i].io_cnt++;
1205 if (io_state & VGA_RSRC_LEGACY_MEM)
1206 priv->cards[i].mem_cnt++;
1207 break;
1208 }
1209 }
1210
1211 ret_val = count;
1212 goto done;
1213 } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
1214 curr_pos += 7;
1215 remaining -= 7;
1216
1217 pr_debug("client 0x%p called 'unlock'\n", priv);
1218
1219 if (strncmp(curr_pos, "all", 3) == 0)
1220 io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
1221 else {
1222 if (!vga_str_to_iostate
1223 (curr_pos, remaining, &io_state)) {
1224 ret_val = -EPROTO;
1225 goto done;
1226 }
1227 /* TODO: Add this?
1228 if (io_state == VGA_RSRC_NONE) {
1229 ret_val = -EPROTO;
1230 goto done;
1231 }
1232 */
1233 }
1234
1235 pdev = priv->target;
1236 if (priv->target == NULL) {
1237 ret_val = -ENODEV;
1238 goto done;
1239 }
1240 for (i = 0; i < MAX_USER_CARDS; i++) {
1241 if (priv->cards[i].pdev == pdev)
1242 uc = &priv->cards[i];
1243 }
1244
1245 if (!uc) {
1246 ret_val = -EINVAL;
1247 goto done;
1248 }
1249
1250 if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {
1251 ret_val = -EINVAL;
1252 goto done;
1253 }
1254
1255 if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {
1256 ret_val = -EINVAL;
1257 goto done;
1258 }
1259
1260 vga_put(pdev, io_state);
1261
1262 if (io_state & VGA_RSRC_LEGACY_IO)
1263 uc->io_cnt--;
1264 if (io_state & VGA_RSRC_LEGACY_MEM)
1265 uc->mem_cnt--;
1266
1267 ret_val = count;
1268 goto done;
1269 } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
1270 curr_pos += 8;
1271 remaining -= 8;
1272
1273 pr_debug("client 0x%p called 'trylock'\n", priv);
1274
1275 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1276 ret_val = -EPROTO;
1277 goto done;
1278 }
1279 /* TODO: Add this?
1280 if (io_state == VGA_RSRC_NONE) {
1281 ret_val = -EPROTO;
1282 goto done;
1283 }
1284 */
1285
1286 pdev = priv->target;
1287 if (priv->target == NULL) {
1288 ret_val = -ENODEV;
1289 goto done;
1290 }
1291
1292 if (vga_tryget(pdev, io_state)) {
1293 /* Update the client's locks lists... */
1294 for (i = 0; i < MAX_USER_CARDS; i++) {
1295 if (priv->cards[i].pdev == pdev) {
1296 if (io_state & VGA_RSRC_LEGACY_IO)
1297 priv->cards[i].io_cnt++;
1298 if (io_state & VGA_RSRC_LEGACY_MEM)
1299 priv->cards[i].mem_cnt++;
1300 break;
1301 }
1302 }
1303 ret_val = count;
1304 goto done;
1305 } else {
1306 ret_val = -EBUSY;
1307 goto done;
1308 }
1309
1310 } else if (strncmp(curr_pos, "target ", 7) == 0) {
1311 unsigned int domain, bus, devfn;
1312 struct vga_device *vgadev;
1313
1314 curr_pos += 7;
1315 remaining -= 7;
1316 pr_debug("client 0x%p called 'target'\n", priv);
1317 /* If target is default */
1318 if (!strncmp(curr_pos, "default", 7))
1319 pdev = pci_dev_get(vga_default_device());
1320 else {
1321 if (!vga_pci_str_to_vars(curr_pos, remaining,
1322 &domain, &bus, &devfn)) {
1323 ret_val = -EPROTO;
1324 goto done;
1325 }
1326 pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
1327 if (!pdev) {
1328 pr_debug("invalid PCI address %04x:%02x:%02x.%x\n",
1329 domain, bus, PCI_SLOT(devfn),
1330 PCI_FUNC(devfn));
1331 ret_val = -ENODEV;
1332 goto done;
1333 }
1334
1335 pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos,
1336 domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
1337 pdev);
1338 }
1339
1340 vgadev = vgadev_find(pdev);
1341 pr_debug("vgadev %p\n", vgadev);
1342 if (vgadev == NULL) {
1343 if (pdev) {
1344 vgaarb_dbg(&pdev->dev, "not a VGA device\n");
1345 pci_dev_put(pdev);
1346 }
1347
1348 ret_val = -ENODEV;
1349 goto done;
1350 }
1351
1352 priv->target = pdev;
1353 for (i = 0; i < MAX_USER_CARDS; i++) {
1354 if (priv->cards[i].pdev == pdev)
1355 break;
1356 if (priv->cards[i].pdev == NULL) {
1357 priv->cards[i].pdev = pdev;
1358 priv->cards[i].io_cnt = 0;
1359 priv->cards[i].mem_cnt = 0;
1360 break;
1361 }
1362 }
1363 if (i == MAX_USER_CARDS) {
1364 vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",
1365 MAX_USER_CARDS);
1366 pci_dev_put(pdev);
1367 /* XXX: Which value to return? */
1368 ret_val = -ENOMEM;
1369 goto done;
1370 }
1371
1372 ret_val = count;
1373 pci_dev_put(pdev);
1374 goto done;
1375
1376
1377 } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
1378 curr_pos += 8;
1379 remaining -= 8;
1380 pr_debug("client 0x%p called 'decodes'\n", priv);
1381
1382 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1383 ret_val = -EPROTO;
1384 goto done;
1385 }
1386 pdev = priv->target;
1387 if (priv->target == NULL) {
1388 ret_val = -ENODEV;
1389 goto done;
1390 }
1391
1392 __vga_set_legacy_decoding(pdev, io_state, true);
1393 ret_val = count;
1394 goto done;
1395 }
1396 /* If we got here, the message written is not part of the protocol! */
1397 return -EPROTO;
1398
1399done:
1400 return ret_val;
1401}
1402
1403static __poll_t vga_arb_fpoll(struct file *file, poll_table *wait)
1404{
1405 pr_debug("%s\n", __func__);
1406
1407 poll_wait(file, &vga_wait_queue, wait);
1408 return EPOLLIN;
1409}
1410
1411static int vga_arb_open(struct inode *inode, struct file *file)
1412{
1413 struct vga_arb_private *priv;
1414 unsigned long flags;
1415
1416 pr_debug("%s\n", __func__);
1417
1418 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1419 if (priv == NULL)
1420 return -ENOMEM;
1421 spin_lock_init(&priv->lock);
1422 file->private_data = priv;
1423
1424 spin_lock_irqsave(&vga_user_lock, flags);
1425 list_add(&priv->list, &vga_user_list);
1426 spin_unlock_irqrestore(&vga_user_lock, flags);
1427
1428 /* Set the client's lists of locks */
1429 priv->target = vga_default_device(); /* Maybe this is still null! */
1430 priv->cards[0].pdev = priv->target;
1431 priv->cards[0].io_cnt = 0;
1432 priv->cards[0].mem_cnt = 0;
1433
1434 return 0;
1435}
1436
1437static int vga_arb_release(struct inode *inode, struct file *file)
1438{
1439 struct vga_arb_private *priv = file->private_data;
1440 struct vga_arb_user_card *uc;
1441 unsigned long flags;
1442 int i;
1443
1444 pr_debug("%s\n", __func__);
1445
1446 spin_lock_irqsave(&vga_user_lock, flags);
1447 list_del(&priv->list);
1448 for (i = 0; i < MAX_USER_CARDS; i++) {
1449 uc = &priv->cards[i];
1450 if (uc->pdev == NULL)
1451 continue;
1452 vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",
1453 uc->io_cnt, uc->mem_cnt);
1454 while (uc->io_cnt--)
1455 vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
1456 while (uc->mem_cnt--)
1457 vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
1458 }
1459 spin_unlock_irqrestore(&vga_user_lock, flags);
1460
1461 kfree(priv);
1462
1463 return 0;
1464}
1465
1466/*
1467 * Callback any registered clients to let them know we have a change in VGA
1468 * cards.
1469 */
1470static void vga_arbiter_notify_clients(void)
1471{
1472 struct vga_device *vgadev;
1473 unsigned long flags;
1474 unsigned int new_decodes;
1475 bool new_state;
1476
1477 if (!vga_arbiter_used)
1478 return;
1479
1480 new_state = (vga_count > 1) ? false : true;
1481
1482 spin_lock_irqsave(&vga_lock, flags);
1483 list_for_each_entry(vgadev, &vga_list, list) {
1484 if (vgadev->set_decode) {
1485 new_decodes = vgadev->set_decode(vgadev->pdev,
1486 new_state);
1487 vga_update_device_decodes(vgadev, new_decodes);
1488 }
1489 }
1490 spin_unlock_irqrestore(&vga_lock, flags);
1491}
1492
1493static int pci_notify(struct notifier_block *nb, unsigned long action,
1494 void *data)
1495{
1496 struct device *dev = data;
1497 struct pci_dev *pdev = to_pci_dev(dev);
1498 bool notify = false;
1499
1500 vgaarb_dbg(dev, "%s\n", __func__);
1501
1502 /* Only deal with VGA class devices */
1503 if (!pci_is_vga(pdev))
1504 return 0;
1505
1506 /*
1507 * For now, we're only interested in devices added and removed.
1508 * I didn't test this thing here, so someone needs to double check
1509 * for the cases of hot-pluggable VGA cards.
1510 */
1511 if (action == BUS_NOTIFY_ADD_DEVICE)
1512 notify = vga_arbiter_add_pci_device(pdev);
1513 else if (action == BUS_NOTIFY_DEL_DEVICE)
1514 notify = vga_arbiter_del_pci_device(pdev);
1515
1516 if (notify)
1517 vga_arbiter_notify_clients();
1518 return 0;
1519}
1520
1521static struct notifier_block pci_notifier = {
1522 .notifier_call = pci_notify,
1523};
1524
1525static const struct file_operations vga_arb_device_fops = {
1526 .read = vga_arb_read,
1527 .write = vga_arb_write,
1528 .poll = vga_arb_fpoll,
1529 .open = vga_arb_open,
1530 .release = vga_arb_release,
1531 .llseek = noop_llseek,
1532};
1533
1534static struct miscdevice vga_arb_device = {
1535 MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
1536};
1537
1538static int __init vga_arb_device_init(void)
1539{
1540 int rc;
1541 struct pci_dev *pdev;
1542
1543 rc = misc_register(&vga_arb_device);
1544 if (rc < 0)
1545 pr_err("error %d registering device\n", rc);
1546
1547 bus_register_notifier(&pci_bus_type, &pci_notifier);
1548
1549 /* Add all VGA class PCI devices by default */
1550 pdev = NULL;
1551 while ((pdev =
1552 pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
1553 PCI_ANY_ID, pdev)) != NULL) {
1554 if (pci_is_vga(pdev))
1555 vga_arbiter_add_pci_device(pdev);
1556 }
1557
1558 pr_info("loaded\n");
1559 return rc;
1560}
1561subsys_initcall_sync(vga_arb_device_init);