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
36 static 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 */
42 struct 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
57 static LIST_HEAD(vga_list);
58 static int vga_count, vga_decode_count;
59 static bool vga_arbiter_used;
60 static DEFINE_SPINLOCK(vga_lock);
61 static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
62
vga_iostate_to_str(unsigned int iostate)63 static 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
vga_str_to_iostate(char * buf,int str_size,unsigned int * io_state)78 static 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;
97 both:
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 */
103 static struct pci_dev *vga_default;
104
105 /* Find somebody in our list */
vgadev_find(struct pci_dev * pdev)106 static 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 */
vga_default_device(void)132 struct pci_dev *vga_default_device(void)
133 {
134 return vga_default;
135 }
136 EXPORT_SYMBOL_GPL(vga_default_device);
137
vga_set_default_device(struct pci_dev * pdev)138 void 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)
vga_remove_vgacon(struct pci_dev * pdev)157 int vga_remove_vgacon(struct pci_dev *pdev)
158 {
159 return 0;
160 }
161 #elif !defined(CONFIG_DUMMY_CONSOLE)
vga_remove_vgacon(struct pci_dev * pdev)162 int vga_remove_vgacon(struct pci_dev *pdev)
163 {
164 return -ENODEV;
165 }
166 #else
vga_remove_vgacon(struct pci_dev * pdev)167 int 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
191 EXPORT_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 */
vga_check_first_use(void)198 static 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
__vga_tryget(struct vga_device * vgadev,unsigned int rsrc)210 static 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
320 enable_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;
343 lock_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
__vga_put(struct vga_device * vgadev,unsigned int rsrc)357 static 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 */
vga_get(struct pci_dev * pdev,unsigned int rsrc,int interruptible)434 int 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 }
484 EXPORT_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 */
vga_tryget(struct pci_dev * pdev,unsigned int rsrc)501 static 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;
522 bail:
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 */
vga_put(struct pci_dev * pdev,unsigned int rsrc)537 void 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);
552 bail:
553 spin_unlock_irqrestore(&vga_lock, flags);
554 }
555 EXPORT_SYMBOL(vga_put);
556
vga_is_firmware_default(struct pci_dev * pdev)557 static 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
vga_arb_integrated_gpu(struct device * dev)566 static 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 */
vga_is_boot_device(struct vga_device * vgadev)581 static 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 /*
656 * Vgadev has neither IO nor MEM enabled. If we haven't found any
657 * other VGA devices, it is the best candidate so far.
658 */
659 if (!boot_vga)
660 return true;
661
662 return false;
663 }
664
665 /*
666 * Rules for using a bridge to control a VGA descendant decoding: if a bridge
667 * has only one VGA descendant then it can be used to control the VGA routing
668 * for that device. It should always use the bridge closest to the device to
669 * control it. If a bridge has a direct VGA descendant, but also have a sub-
670 * bridge VGA descendant then we cannot use that bridge to control the direct
671 * VGA descendant. So for every device we register, we need to iterate all
672 * its parent bridges so we can invalidate any devices using them properly.
673 */
vga_arbiter_check_bridge_sharing(struct vga_device * vgadev)674 static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
675 {
676 struct vga_device *same_bridge_vgadev;
677 struct pci_bus *new_bus, *bus;
678 struct pci_dev *new_bridge, *bridge;
679
680 vgadev->bridge_has_one_vga = true;
681
682 if (list_empty(&vga_list)) {
683 vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
684 return;
685 }
686
687 /* Iterate the new device's bridge hierarchy */
688 new_bus = vgadev->pdev->bus;
689 while (new_bus) {
690 new_bridge = new_bus->self;
691
692 /* Go through list of devices already registered */
693 list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
694 bus = same_bridge_vgadev->pdev->bus;
695 bridge = bus->self;
696
697 /* See if it shares a bridge with this device */
698 if (new_bridge == bridge) {
699 /*
700 * If its direct parent bridge is the same
701 * as any bridge of this device then it can't
702 * be used for that device.
703 */
704 same_bridge_vgadev->bridge_has_one_vga = false;
705 }
706
707 /*
708 * Now iterate the previous device's bridge hierarchy.
709 * If the new device's parent bridge is in the other
710 * device's hierarchy, we can't use it to control this
711 * device.
712 */
713 while (bus) {
714 bridge = bus->self;
715
716 if (bridge && bridge == vgadev->pdev->bus->self)
717 vgadev->bridge_has_one_vga = false;
718
719 bus = bus->parent;
720 }
721 }
722 new_bus = new_bus->parent;
723 }
724
725 if (vgadev->bridge_has_one_vga)
726 vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
727 else
728 vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
729 }
730
731 /*
732 * Currently, we assume that the "initial" setup of the system is not sane,
733 * that is, we come up with conflicting devices and let the arbiter's
734 * client decide if devices decodes legacy things or not.
735 */
vga_arbiter_add_pci_device(struct pci_dev * pdev)736 static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
737 {
738 struct vga_device *vgadev;
739 unsigned long flags;
740 struct pci_bus *bus;
741 struct pci_dev *bridge;
742 u16 cmd;
743
744 /* Allocate structure */
745 vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
746 if (vgadev == NULL) {
747 vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
748 /*
749 * What to do on allocation failure? For now, let's just do
750 * nothing, I'm not sure there is anything saner to be done.
751 */
752 return false;
753 }
754
755 /* Take lock & check for duplicates */
756 spin_lock_irqsave(&vga_lock, flags);
757 if (vgadev_find(pdev) != NULL) {
758 BUG_ON(1);
759 goto fail;
760 }
761 vgadev->pdev = pdev;
762
763 /* By default, assume we decode everything */
764 vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
765 VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
766
767 /* By default, mark it as decoding */
768 vga_decode_count++;
769
770 /*
771 * Mark that we "own" resources based on our enables, we will
772 * clear that below if the bridge isn't forwarding.
773 */
774 pci_read_config_word(pdev, PCI_COMMAND, &cmd);
775 if (cmd & PCI_COMMAND_IO)
776 vgadev->owns |= VGA_RSRC_LEGACY_IO;
777 if (cmd & PCI_COMMAND_MEMORY)
778 vgadev->owns |= VGA_RSRC_LEGACY_MEM;
779
780 /* Check if VGA cycles can get down to us */
781 bus = pdev->bus;
782 while (bus) {
783 bridge = bus->self;
784 if (bridge) {
785 u16 l;
786
787 pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l);
788 if (!(l & PCI_BRIDGE_CTL_VGA)) {
789 vgadev->owns = 0;
790 break;
791 }
792 }
793 bus = bus->parent;
794 }
795
796 if (vga_is_boot_device(vgadev)) {
797 vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
798 vga_default_device() ?
799 " (overriding previous)" : "");
800 vga_set_default_device(pdev);
801 }
802
803 vga_arbiter_check_bridge_sharing(vgadev);
804
805 /* Add to the list */
806 list_add_tail(&vgadev->list, &vga_list);
807 vga_count++;
808 vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
809 vga_iostate_to_str(vgadev->decodes),
810 vga_iostate_to_str(vgadev->owns),
811 vga_iostate_to_str(vgadev->locks));
812
813 spin_unlock_irqrestore(&vga_lock, flags);
814 return true;
815 fail:
816 spin_unlock_irqrestore(&vga_lock, flags);
817 kfree(vgadev);
818 return false;
819 }
820
vga_arbiter_del_pci_device(struct pci_dev * pdev)821 static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
822 {
823 struct vga_device *vgadev;
824 unsigned long flags;
825 bool ret = true;
826
827 spin_lock_irqsave(&vga_lock, flags);
828 vgadev = vgadev_find(pdev);
829 if (vgadev == NULL) {
830 ret = false;
831 goto bail;
832 }
833
834 if (vga_default == pdev)
835 vga_set_default_device(NULL);
836
837 if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
838 vga_decode_count--;
839
840 /* Remove entry from list */
841 list_del(&vgadev->list);
842 vga_count--;
843
844 /* Wake up all possible waiters */
845 wake_up_all(&vga_wait_queue);
846 bail:
847 spin_unlock_irqrestore(&vga_lock, flags);
848 kfree(vgadev);
849 return ret;
850 }
851
852 /* Called with the lock */
vga_update_device_decodes(struct vga_device * vgadev,unsigned int new_decodes)853 static void vga_update_device_decodes(struct vga_device *vgadev,
854 unsigned int new_decodes)
855 {
856 struct device *dev = &vgadev->pdev->dev;
857 unsigned int old_decodes = vgadev->decodes;
858 unsigned int decodes_removed = ~new_decodes & old_decodes;
859 unsigned int decodes_unlocked = vgadev->locks & decodes_removed;
860
861 vgadev->decodes = new_decodes;
862
863 vgaarb_info(dev, "VGA decodes changed: olddecodes=%s,decodes=%s:owns=%s\n",
864 vga_iostate_to_str(old_decodes),
865 vga_iostate_to_str(vgadev->decodes),
866 vga_iostate_to_str(vgadev->owns));
867
868 /* If we removed locked decodes, lock count goes to zero, and release */
869 if (decodes_unlocked) {
870 if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
871 vgadev->io_lock_cnt = 0;
872 if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
873 vgadev->mem_lock_cnt = 0;
874 __vga_put(vgadev, decodes_unlocked);
875 }
876
877 /* Change decodes counter */
878 if (old_decodes & VGA_RSRC_LEGACY_MASK &&
879 !(new_decodes & VGA_RSRC_LEGACY_MASK))
880 vga_decode_count--;
881 if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
882 new_decodes & VGA_RSRC_LEGACY_MASK)
883 vga_decode_count++;
884 vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
885 }
886
__vga_set_legacy_decoding(struct pci_dev * pdev,unsigned int decodes,bool userspace)887 static void __vga_set_legacy_decoding(struct pci_dev *pdev,
888 unsigned int decodes,
889 bool userspace)
890 {
891 struct vga_device *vgadev;
892 unsigned long flags;
893
894 decodes &= VGA_RSRC_LEGACY_MASK;
895
896 spin_lock_irqsave(&vga_lock, flags);
897 vgadev = vgadev_find(pdev);
898 if (vgadev == NULL)
899 goto bail;
900
901 /* Don't let userspace futz with kernel driver decodes */
902 if (userspace && vgadev->set_decode)
903 goto bail;
904
905 /* Update the device decodes + counter */
906 vga_update_device_decodes(vgadev, decodes);
907
908 /*
909 * XXX If somebody is going from "doesn't decode" to "decodes"
910 * state here, additional care must be taken as we may have pending
911 * ownership of non-legacy region.
912 */
913 bail:
914 spin_unlock_irqrestore(&vga_lock, flags);
915 }
916
917 /**
918 * vga_set_legacy_decoding
919 * @pdev: PCI device of the VGA card
920 * @decodes: bit mask of what legacy regions the card decodes
921 *
922 * Indicate to the arbiter if the card decodes legacy VGA IOs, legacy VGA
923 * Memory, both, or none. All cards default to both, the card driver (fbdev for
924 * example) should tell the arbiter if it has disabled legacy decoding, so the
925 * card can be left out of the arbitration process (and can be safe to take
926 * interrupts at any time.
927 */
vga_set_legacy_decoding(struct pci_dev * pdev,unsigned int decodes)928 void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
929 {
930 __vga_set_legacy_decoding(pdev, decodes, false);
931 }
932 EXPORT_SYMBOL(vga_set_legacy_decoding);
933
934 /**
935 * vga_client_register - register or unregister a VGA arbitration client
936 * @pdev: PCI device of the VGA client
937 * @set_decode: VGA decode change callback
938 *
939 * Clients have two callback mechanisms they can use.
940 *
941 * @set_decode callback: If a client can disable its GPU VGA resource, it
942 * will get a callback from this to set the encode/decode state.
943 *
944 * Rationale: we cannot disable VGA decode resources unconditionally
945 * because some single GPU laptops seem to require ACPI or BIOS access to
946 * the VGA registers to control things like backlights etc. Hopefully newer
947 * multi-GPU laptops do something saner, and desktops won't have any
948 * special ACPI for this. The driver will get a callback when VGA
949 * arbitration is first used by userspace since some older X servers have
950 * issues.
951 *
952 * Does not check whether a client for @pdev has been registered already.
953 *
954 * To unregister, call vga_client_unregister().
955 *
956 * Returns: 0 on success, -ENODEV on failure
957 */
vga_client_register(struct pci_dev * pdev,unsigned int (* set_decode)(struct pci_dev * pdev,bool decode))958 int vga_client_register(struct pci_dev *pdev,
959 unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
960 {
961 unsigned long flags;
962 struct vga_device *vgadev;
963
964 spin_lock_irqsave(&vga_lock, flags);
965 vgadev = vgadev_find(pdev);
966 if (vgadev)
967 vgadev->set_decode = set_decode;
968 spin_unlock_irqrestore(&vga_lock, flags);
969 if (!vgadev)
970 return -ENODEV;
971 return 0;
972 }
973 EXPORT_SYMBOL(vga_client_register);
974
975 /*
976 * Char driver implementation
977 *
978 * Semantics is:
979 *
980 * open : Open user instance of the arbiter. By default, it's
981 * attached to the default VGA device of the system.
982 *
983 * close : Close user instance, release locks
984 *
985 * read : Return a string indicating the status of the target.
986 * An IO state string is of the form {io,mem,io+mem,none},
987 * mc and ic are respectively mem and io lock counts (for
988 * debugging/diagnostic only). "decodes" indicate what the
989 * card currently decodes, "owns" indicates what is currently
990 * enabled on it, and "locks" indicates what is locked by this
991 * card. If the card is unplugged, we get "invalid" then for
992 * card_ID and an -ENODEV error is returned for any command
993 * until a new card is targeted
994 *
995 * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
996 *
997 * write : write a command to the arbiter. List of commands is:
998 *
999 * target <card_ID> : switch target to card <card_ID> (see below)
1000 * lock <io_state> : acquire locks on target ("none" is invalid io_state)
1001 * trylock <io_state> : non-blocking acquire locks on target
1002 * unlock <io_state> : release locks on target
1003 * unlock all : release all locks on target held by this user
1004 * decodes <io_state> : set the legacy decoding attributes for the card
1005 *
1006 * poll : event if something change on any card (not just the target)
1007 *
1008 * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
1009 * to go back to the system default card (TODO: not implemented yet).
1010 * Currently, only PCI is supported as a prefix, but the userland API may
1011 * support other bus types in the future, even if the current kernel
1012 * implementation doesn't.
1013 *
1014 * Note about locks:
1015 *
1016 * The driver keeps track of which user has what locks on which card. It
1017 * supports stacking, like the kernel one. This complicates the implementation
1018 * a bit, but makes the arbiter more tolerant to userspace problems and able
1019 * to properly cleanup in all cases when a process dies.
1020 * Currently, a max of 16 cards simultaneously can have locks issued from
1021 * userspace for a given user (file descriptor instance) of the arbiter.
1022 *
1023 * If the device is hot-unplugged, there is a hook inside the module to notify
1024 * it being added/removed in the system and automatically added/removed in
1025 * the arbiter.
1026 */
1027
1028 #define MAX_USER_CARDS CONFIG_VGA_ARB_MAX_GPUS
1029 #define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
1030
1031 /* Each user has an array of these, tracking which cards have locks */
1032 struct vga_arb_user_card {
1033 struct pci_dev *pdev;
1034 unsigned int mem_cnt;
1035 unsigned int io_cnt;
1036 };
1037
1038 struct vga_arb_private {
1039 struct list_head list;
1040 struct pci_dev *target;
1041 struct vga_arb_user_card cards[MAX_USER_CARDS];
1042 spinlock_t lock;
1043 };
1044
1045 static LIST_HEAD(vga_user_list);
1046 static DEFINE_SPINLOCK(vga_user_lock);
1047
1048
1049 /*
1050 * Take a string in the format: "PCI:domain:bus:dev.fn" and return the
1051 * respective values. If the string is not in this format, return 0.
1052 */
vga_pci_str_to_vars(char * buf,int count,unsigned int * domain,unsigned int * bus,unsigned int * devfn)1053 static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
1054 unsigned int *bus, unsigned int *devfn)
1055 {
1056 int n;
1057 unsigned int slot, func;
1058
1059 n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
1060 if (n != 4)
1061 return 0;
1062
1063 *devfn = PCI_DEVFN(slot, func);
1064
1065 return 1;
1066 }
1067
vga_arb_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)1068 static ssize_t vga_arb_read(struct file *file, char __user *buf,
1069 size_t count, loff_t *ppos)
1070 {
1071 struct vga_arb_private *priv = file->private_data;
1072 struct vga_device *vgadev;
1073 struct pci_dev *pdev;
1074 unsigned long flags;
1075 size_t len;
1076 int rc;
1077 char *lbuf;
1078
1079 lbuf = kmalloc(1024, GFP_KERNEL);
1080 if (lbuf == NULL)
1081 return -ENOMEM;
1082
1083 /* Protect vga_list */
1084 spin_lock_irqsave(&vga_lock, flags);
1085
1086 /* If we are targeting the default, use it */
1087 pdev = priv->target;
1088 if (pdev == NULL || pdev == PCI_INVALID_CARD) {
1089 spin_unlock_irqrestore(&vga_lock, flags);
1090 len = sprintf(lbuf, "invalid");
1091 goto done;
1092 }
1093
1094 /* Find card vgadev structure */
1095 vgadev = vgadev_find(pdev);
1096 if (vgadev == NULL) {
1097 /*
1098 * Wow, it's not in the list, that shouldn't happen, let's
1099 * fix us up and return invalid card.
1100 */
1101 spin_unlock_irqrestore(&vga_lock, flags);
1102 len = sprintf(lbuf, "invalid");
1103 goto done;
1104 }
1105
1106 /* Fill the buffer with info */
1107 len = snprintf(lbuf, 1024,
1108 "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%u:%u)\n",
1109 vga_decode_count, pci_name(pdev),
1110 vga_iostate_to_str(vgadev->decodes),
1111 vga_iostate_to_str(vgadev->owns),
1112 vga_iostate_to_str(vgadev->locks),
1113 vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
1114
1115 spin_unlock_irqrestore(&vga_lock, flags);
1116 done:
1117
1118 /* Copy that to user */
1119 if (len > count)
1120 len = count;
1121 rc = copy_to_user(buf, lbuf, len);
1122 kfree(lbuf);
1123 if (rc)
1124 return -EFAULT;
1125 return len;
1126 }
1127
1128 /*
1129 * TODO: To avoid parsing inside kernel and to improve the speed we may
1130 * consider use ioctl here
1131 */
vga_arb_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)1132 static ssize_t vga_arb_write(struct file *file, const char __user *buf,
1133 size_t count, loff_t *ppos)
1134 {
1135 struct vga_arb_private *priv = file->private_data;
1136 struct vga_arb_user_card *uc = NULL;
1137 struct pci_dev *pdev;
1138
1139 unsigned int io_state;
1140
1141 char kbuf[64], *curr_pos;
1142 size_t remaining = count;
1143
1144 int ret_val;
1145 int i;
1146
1147 if (count >= sizeof(kbuf))
1148 return -EINVAL;
1149 if (copy_from_user(kbuf, buf, count))
1150 return -EFAULT;
1151 curr_pos = kbuf;
1152 kbuf[count] = '\0';
1153
1154 if (strncmp(curr_pos, "lock ", 5) == 0) {
1155 curr_pos += 5;
1156 remaining -= 5;
1157
1158 pr_debug("client 0x%p called 'lock'\n", priv);
1159
1160 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1161 ret_val = -EPROTO;
1162 goto done;
1163 }
1164 if (io_state == VGA_RSRC_NONE) {
1165 ret_val = -EPROTO;
1166 goto done;
1167 }
1168
1169 pdev = priv->target;
1170 if (priv->target == NULL) {
1171 ret_val = -ENODEV;
1172 goto done;
1173 }
1174
1175 vga_get_uninterruptible(pdev, io_state);
1176
1177 /* Update the client's locks lists */
1178 for (i = 0; i < MAX_USER_CARDS; i++) {
1179 if (priv->cards[i].pdev == pdev) {
1180 if (io_state & VGA_RSRC_LEGACY_IO)
1181 priv->cards[i].io_cnt++;
1182 if (io_state & VGA_RSRC_LEGACY_MEM)
1183 priv->cards[i].mem_cnt++;
1184 break;
1185 }
1186 }
1187
1188 ret_val = count;
1189 goto done;
1190 } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
1191 curr_pos += 7;
1192 remaining -= 7;
1193
1194 pr_debug("client 0x%p called 'unlock'\n", priv);
1195
1196 if (strncmp(curr_pos, "all", 3) == 0)
1197 io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
1198 else {
1199 if (!vga_str_to_iostate
1200 (curr_pos, remaining, &io_state)) {
1201 ret_val = -EPROTO;
1202 goto done;
1203 }
1204 /* TODO: Add this?
1205 if (io_state == VGA_RSRC_NONE) {
1206 ret_val = -EPROTO;
1207 goto done;
1208 }
1209 */
1210 }
1211
1212 pdev = priv->target;
1213 if (priv->target == NULL) {
1214 ret_val = -ENODEV;
1215 goto done;
1216 }
1217 for (i = 0; i < MAX_USER_CARDS; i++) {
1218 if (priv->cards[i].pdev == pdev)
1219 uc = &priv->cards[i];
1220 }
1221
1222 if (!uc) {
1223 ret_val = -EINVAL;
1224 goto done;
1225 }
1226
1227 if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {
1228 ret_val = -EINVAL;
1229 goto done;
1230 }
1231
1232 if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {
1233 ret_val = -EINVAL;
1234 goto done;
1235 }
1236
1237 vga_put(pdev, io_state);
1238
1239 if (io_state & VGA_RSRC_LEGACY_IO)
1240 uc->io_cnt--;
1241 if (io_state & VGA_RSRC_LEGACY_MEM)
1242 uc->mem_cnt--;
1243
1244 ret_val = count;
1245 goto done;
1246 } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
1247 curr_pos += 8;
1248 remaining -= 8;
1249
1250 pr_debug("client 0x%p called 'trylock'\n", priv);
1251
1252 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1253 ret_val = -EPROTO;
1254 goto done;
1255 }
1256 /* TODO: Add this?
1257 if (io_state == VGA_RSRC_NONE) {
1258 ret_val = -EPROTO;
1259 goto done;
1260 }
1261 */
1262
1263 pdev = priv->target;
1264 if (priv->target == NULL) {
1265 ret_val = -ENODEV;
1266 goto done;
1267 }
1268
1269 if (vga_tryget(pdev, io_state)) {
1270 /* Update the client's locks lists... */
1271 for (i = 0; i < MAX_USER_CARDS; i++) {
1272 if (priv->cards[i].pdev == pdev) {
1273 if (io_state & VGA_RSRC_LEGACY_IO)
1274 priv->cards[i].io_cnt++;
1275 if (io_state & VGA_RSRC_LEGACY_MEM)
1276 priv->cards[i].mem_cnt++;
1277 break;
1278 }
1279 }
1280 ret_val = count;
1281 goto done;
1282 } else {
1283 ret_val = -EBUSY;
1284 goto done;
1285 }
1286
1287 } else if (strncmp(curr_pos, "target ", 7) == 0) {
1288 unsigned int domain, bus, devfn;
1289 struct vga_device *vgadev;
1290
1291 curr_pos += 7;
1292 remaining -= 7;
1293 pr_debug("client 0x%p called 'target'\n", priv);
1294 /* If target is default */
1295 if (!strncmp(curr_pos, "default", 7))
1296 pdev = pci_dev_get(vga_default_device());
1297 else {
1298 if (!vga_pci_str_to_vars(curr_pos, remaining,
1299 &domain, &bus, &devfn)) {
1300 ret_val = -EPROTO;
1301 goto done;
1302 }
1303 pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
1304 if (!pdev) {
1305 pr_debug("invalid PCI address %04x:%02x:%02x.%x\n",
1306 domain, bus, PCI_SLOT(devfn),
1307 PCI_FUNC(devfn));
1308 ret_val = -ENODEV;
1309 goto done;
1310 }
1311
1312 pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos,
1313 domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
1314 pdev);
1315 }
1316
1317 vgadev = vgadev_find(pdev);
1318 pr_debug("vgadev %p\n", vgadev);
1319 if (vgadev == NULL) {
1320 if (pdev) {
1321 vgaarb_dbg(&pdev->dev, "not a VGA device\n");
1322 pci_dev_put(pdev);
1323 }
1324
1325 ret_val = -ENODEV;
1326 goto done;
1327 }
1328
1329 priv->target = pdev;
1330 for (i = 0; i < MAX_USER_CARDS; i++) {
1331 if (priv->cards[i].pdev == pdev)
1332 break;
1333 if (priv->cards[i].pdev == NULL) {
1334 priv->cards[i].pdev = pdev;
1335 priv->cards[i].io_cnt = 0;
1336 priv->cards[i].mem_cnt = 0;
1337 break;
1338 }
1339 }
1340 if (i == MAX_USER_CARDS) {
1341 vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",
1342 MAX_USER_CARDS);
1343 pci_dev_put(pdev);
1344 /* XXX: Which value to return? */
1345 ret_val = -ENOMEM;
1346 goto done;
1347 }
1348
1349 ret_val = count;
1350 pci_dev_put(pdev);
1351 goto done;
1352
1353
1354 } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
1355 curr_pos += 8;
1356 remaining -= 8;
1357 pr_debug("client 0x%p called 'decodes'\n", priv);
1358
1359 if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
1360 ret_val = -EPROTO;
1361 goto done;
1362 }
1363 pdev = priv->target;
1364 if (priv->target == NULL) {
1365 ret_val = -ENODEV;
1366 goto done;
1367 }
1368
1369 __vga_set_legacy_decoding(pdev, io_state, true);
1370 ret_val = count;
1371 goto done;
1372 }
1373 /* If we got here, the message written is not part of the protocol! */
1374 return -EPROTO;
1375
1376 done:
1377 return ret_val;
1378 }
1379
vga_arb_fpoll(struct file * file,poll_table * wait)1380 static __poll_t vga_arb_fpoll(struct file *file, poll_table *wait)
1381 {
1382 pr_debug("%s\n", __func__);
1383
1384 poll_wait(file, &vga_wait_queue, wait);
1385 return EPOLLIN;
1386 }
1387
vga_arb_open(struct inode * inode,struct file * file)1388 static int vga_arb_open(struct inode *inode, struct file *file)
1389 {
1390 struct vga_arb_private *priv;
1391 unsigned long flags;
1392
1393 pr_debug("%s\n", __func__);
1394
1395 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1396 if (priv == NULL)
1397 return -ENOMEM;
1398 spin_lock_init(&priv->lock);
1399 file->private_data = priv;
1400
1401 spin_lock_irqsave(&vga_user_lock, flags);
1402 list_add(&priv->list, &vga_user_list);
1403 spin_unlock_irqrestore(&vga_user_lock, flags);
1404
1405 /* Set the client's lists of locks */
1406 priv->target = vga_default_device(); /* Maybe this is still null! */
1407 priv->cards[0].pdev = priv->target;
1408 priv->cards[0].io_cnt = 0;
1409 priv->cards[0].mem_cnt = 0;
1410
1411 return 0;
1412 }
1413
vga_arb_release(struct inode * inode,struct file * file)1414 static int vga_arb_release(struct inode *inode, struct file *file)
1415 {
1416 struct vga_arb_private *priv = file->private_data;
1417 struct vga_arb_user_card *uc;
1418 unsigned long flags;
1419 int i;
1420
1421 pr_debug("%s\n", __func__);
1422
1423 spin_lock_irqsave(&vga_user_lock, flags);
1424 list_del(&priv->list);
1425 for (i = 0; i < MAX_USER_CARDS; i++) {
1426 uc = &priv->cards[i];
1427 if (uc->pdev == NULL)
1428 continue;
1429 vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",
1430 uc->io_cnt, uc->mem_cnt);
1431 while (uc->io_cnt--)
1432 vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
1433 while (uc->mem_cnt--)
1434 vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
1435 }
1436 spin_unlock_irqrestore(&vga_user_lock, flags);
1437
1438 kfree(priv);
1439
1440 return 0;
1441 }
1442
1443 /*
1444 * Callback any registered clients to let them know we have a change in VGA
1445 * cards.
1446 */
vga_arbiter_notify_clients(void)1447 static void vga_arbiter_notify_clients(void)
1448 {
1449 struct vga_device *vgadev;
1450 unsigned long flags;
1451 unsigned int new_decodes;
1452 bool new_state;
1453
1454 if (!vga_arbiter_used)
1455 return;
1456
1457 new_state = (vga_count > 1) ? false : true;
1458
1459 spin_lock_irqsave(&vga_lock, flags);
1460 list_for_each_entry(vgadev, &vga_list, list) {
1461 if (vgadev->set_decode) {
1462 new_decodes = vgadev->set_decode(vgadev->pdev,
1463 new_state);
1464 vga_update_device_decodes(vgadev, new_decodes);
1465 }
1466 }
1467 spin_unlock_irqrestore(&vga_lock, flags);
1468 }
1469
pci_notify(struct notifier_block * nb,unsigned long action,void * data)1470 static int pci_notify(struct notifier_block *nb, unsigned long action,
1471 void *data)
1472 {
1473 struct device *dev = data;
1474 struct pci_dev *pdev = to_pci_dev(dev);
1475 bool notify = false;
1476
1477 vgaarb_dbg(dev, "%s\n", __func__);
1478
1479 /* Only deal with VGA class devices */
1480 if (!pci_is_vga(pdev))
1481 return 0;
1482
1483 /*
1484 * For now, we're only interested in devices added and removed.
1485 * I didn't test this thing here, so someone needs to double check
1486 * for the cases of hot-pluggable VGA cards.
1487 */
1488 if (action == BUS_NOTIFY_ADD_DEVICE)
1489 notify = vga_arbiter_add_pci_device(pdev);
1490 else if (action == BUS_NOTIFY_DEL_DEVICE)
1491 notify = vga_arbiter_del_pci_device(pdev);
1492
1493 if (notify)
1494 vga_arbiter_notify_clients();
1495 return 0;
1496 }
1497
1498 static struct notifier_block pci_notifier = {
1499 .notifier_call = pci_notify,
1500 };
1501
1502 static const struct file_operations vga_arb_device_fops = {
1503 .read = vga_arb_read,
1504 .write = vga_arb_write,
1505 .poll = vga_arb_fpoll,
1506 .open = vga_arb_open,
1507 .release = vga_arb_release,
1508 .llseek = noop_llseek,
1509 };
1510
1511 static struct miscdevice vga_arb_device = {
1512 MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
1513 };
1514
vga_arb_device_init(void)1515 static int __init vga_arb_device_init(void)
1516 {
1517 int rc;
1518 struct pci_dev *pdev;
1519
1520 rc = misc_register(&vga_arb_device);
1521 if (rc < 0)
1522 pr_err("error %d registering device\n", rc);
1523
1524 bus_register_notifier(&pci_bus_type, &pci_notifier);
1525
1526 /* Add all VGA class PCI devices by default */
1527 pdev = NULL;
1528 while ((pdev =
1529 pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
1530 PCI_ANY_ID, pdev)) != NULL) {
1531 if (pci_is_vga(pdev))
1532 vga_arbiter_add_pci_device(pdev);
1533 }
1534
1535 pr_info("loaded\n");
1536 return rc;
1537 }
1538 subsys_initcall_sync(vga_arb_device_init);
1539