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(dev: vga_default);
144 vga_default = pci_dev_get(dev: 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(csw: &vga_con))
177 ret = do_take_over_console(sw: &dummy_con, first: 0,
178 MAX_NR_CONSOLES - 1, deflt: 1);
179 if (ret == 0) {
180 ret = do_unregister_con_driver(csw: &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(pdev: conflict->pdev, decode: false, command_bits: 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(pdev: vgadev->pdev, decode: true, command_bits: 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(lock: &vga_lock, flags);
453 rc = -ENODEV;
454 break;
455 }
456 conflict = __vga_tryget(vgadev, rsrc);
457 spin_unlock_irqrestore(lock: &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(wq_entry: &wait, current);
469 add_wait_queue(wq_head: &vga_wait_queue, wq_entry: &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(wq_head: &vga_wait_queue, wq_entry: &wait);
476 rc = -ERESTARTSYS;
477 break;
478 }
479 schedule();
480 remove_wait_queue(wq_head: &vga_wait_queue, wq_entry: &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(lock: &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(lock: &vga_lock, flags);
554}
555EXPORT_SYMBOL(vga_put);
556
557static bool vga_is_firmware_default(struct pci_dev *pdev)
558{
559#ifdef CONFIG_SCREEN_INFO
560 struct screen_info *si = &screen_info;
561
562 return pdev == screen_info_pci_dev(si);
563#else
564 return false;
565#endif
566}
567
568static bool vga_arb_integrated_gpu(struct device *dev)
569{
570#if defined(CONFIG_ACPI)
571 struct acpi_device *adev = ACPI_COMPANION(dev);
572
573 return adev && !strcmp(acpi_device_hid(device: adev), ACPI_VIDEO_HID);
574#else
575 return false;
576#endif
577}
578
579/*
580 * Return true if vgadev is a better default VGA device than the best one
581 * we've seen so far.
582 */
583static bool vga_is_boot_device(struct vga_device *vgadev)
584{
585 struct vga_device *boot_vga = vgadev_find(pdev: vga_default_device());
586 struct pci_dev *pdev = vgadev->pdev;
587 u16 cmd, boot_cmd;
588
589 /*
590 * We select the default VGA device in this order:
591 * Firmware framebuffer (see vga_arb_select_default_device())
592 * Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)
593 * Non-legacy integrated device (see vga_arb_select_default_device())
594 * Non-legacy discrete device (see vga_arb_select_default_device())
595 * Other device (see vga_arb_select_default_device())
596 */
597
598 /*
599 * We always prefer a firmware default device, so if we've already
600 * found one, there's no need to consider vgadev.
601 */
602 if (boot_vga && boot_vga->is_firmware_default)
603 return false;
604
605 if (vga_is_firmware_default(pdev)) {
606 vgadev->is_firmware_default = true;
607 return true;
608 }
609
610 /*
611 * A legacy VGA device has MEM and IO enabled and any bridges
612 * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy
613 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are
614 * routed to it.
615 *
616 * We use the first one we find, so if we've already found one,
617 * vgadev is no better.
618 */
619 if (boot_vga &&
620 (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
621 return false;
622
623 if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
624 return true;
625
626 /*
627 * If we haven't found a legacy VGA device, accept a non-legacy
628 * device. It may have either IO or MEM enabled, and bridges may
629 * not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to
630 * use legacy VGA resources. Prefer an integrated GPU over others.
631 */
632 pci_read_config_word(dev: pdev, PCI_COMMAND, val: &cmd);
633 if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
634
635 /*
636 * An integrated GPU overrides a previous non-legacy
637 * device. We expect only a single integrated GPU, but if
638 * there are more, we use the *last* because that was the
639 * previous behavior.
640 */
641 if (vga_arb_integrated_gpu(dev: &pdev->dev))
642 return true;
643
644 /*
645 * We prefer the first non-legacy discrete device we find.
646 * If we already found one, vgadev is no better.
647 */
648 if (boot_vga) {
649 pci_read_config_word(dev: boot_vga->pdev, PCI_COMMAND,
650 val: &boot_cmd);
651 if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
652 return false;
653 }
654 return true;
655 }
656
657 /*
658 * Vgadev has neither IO nor MEM enabled. If we haven't found any
659 * other VGA devices, it is the best candidate so far.
660 */
661 if (!boot_vga)
662 return true;
663
664 return false;
665}
666
667/*
668 * Rules for using a bridge to control a VGA descendant decoding: if a bridge
669 * has only one VGA descendant then it can be used to control the VGA routing
670 * for that device. It should always use the bridge closest to the device to
671 * control it. If a bridge has a direct VGA descendant, but also have a sub-
672 * bridge VGA descendant then we cannot use that bridge to control the direct
673 * VGA descendant. So for every device we register, we need to iterate all
674 * its parent bridges so we can invalidate any devices using them properly.
675 */
676static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
677{
678 struct vga_device *same_bridge_vgadev;
679 struct pci_bus *new_bus, *bus;
680 struct pci_dev *new_bridge, *bridge;
681
682 vgadev->bridge_has_one_vga = true;
683
684 if (list_empty(head: &vga_list)) {
685 vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
686 return;
687 }
688
689 /* Iterate the new device's bridge hierarchy */
690 new_bus = vgadev->pdev->bus;
691 while (new_bus) {
692 new_bridge = new_bus->self;
693
694 /* Go through list of devices already registered */
695 list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
696 bus = same_bridge_vgadev->pdev->bus;
697 bridge = bus->self;
698
699 /* See if it shares a bridge with this device */
700 if (new_bridge == bridge) {
701 /*
702 * If its direct parent bridge is the same
703 * as any bridge of this device then it can't
704 * be used for that device.
705 */
706 same_bridge_vgadev->bridge_has_one_vga = false;
707 }
708
709 /*
710 * Now iterate the previous device's bridge hierarchy.
711 * If the new device's parent bridge is in the other
712 * device's hierarchy, we can't use it to control this
713 * device.
714 */
715 while (bus) {
716 bridge = bus->self;
717
718 if (bridge && bridge == vgadev->pdev->bus->self)
719 vgadev->bridge_has_one_vga = false;
720
721 bus = bus->parent;
722 }
723 }
724 new_bus = new_bus->parent;
725 }
726
727 if (vgadev->bridge_has_one_vga)
728 vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
729 else
730 vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
731}
732
733/*
734 * Currently, we assume that the "initial" setup of the system is not sane,
735 * that is, we come up with conflicting devices and let the arbiter's
736 * client decide if devices decodes legacy things or not.
737 */
738static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
739{
740 struct vga_device *vgadev;
741 unsigned long flags;
742 struct pci_bus *bus;
743 struct pci_dev *bridge;
744 u16 cmd;
745
746 /* Allocate structure */
747 vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
748 if (vgadev == NULL) {
749 vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
750 /*
751 * What to do on allocation failure? For now, let's just do
752 * nothing, I'm not sure there is anything saner to be done.
753 */
754 return false;
755 }
756
757 /* Take lock & check for duplicates */
758 spin_lock_irqsave(&vga_lock, flags);
759 if (vgadev_find(pdev) != NULL) {
760 BUG_ON(1);
761 goto fail;
762 }
763 vgadev->pdev = pdev;
764
765 /* By default, assume we decode everything */
766 vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
767 VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
768
769 /* By default, mark it as decoding */
770 vga_decode_count++;
771
772 /*
773 * Mark that we "own" resources based on our enables, we will
774 * clear that below if the bridge isn't forwarding.
775 */
776 pci_read_config_word(dev: pdev, PCI_COMMAND, val: &cmd);
777 if (cmd & PCI_COMMAND_IO)
778 vgadev->owns |= VGA_RSRC_LEGACY_IO;
779 if (cmd & PCI_COMMAND_MEMORY)
780 vgadev->owns |= VGA_RSRC_LEGACY_MEM;
781
782 /* Check if VGA cycles can get down to us */
783 bus = pdev->bus;
784 while (bus) {
785 bridge = bus->self;
786 if (bridge) {
787 u16 l;
788
789 pci_read_config_word(dev: bridge, PCI_BRIDGE_CONTROL, val: &l);
790 if (!(l & PCI_BRIDGE_CTL_VGA)) {
791 vgadev->owns = 0;
792 break;
793 }
794 }
795 bus = bus->parent;
796 }
797
798 if (vga_is_boot_device(vgadev)) {
799 vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
800 vga_default_device() ?
801 " (overriding previous)" : "");
802 vga_set_default_device(pdev);
803 }
804
805 vga_arbiter_check_bridge_sharing(vgadev);
806
807 /* Add to the list */
808 list_add_tail(new: &vgadev->list, head: &vga_list);
809 vga_count++;
810 vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
811 vga_iostate_to_str(vgadev->decodes),
812 vga_iostate_to_str(vgadev->owns),
813 vga_iostate_to_str(vgadev->locks));
814
815 spin_unlock_irqrestore(lock: &vga_lock, flags);
816 return true;
817fail:
818 spin_unlock_irqrestore(lock: &vga_lock, flags);
819 kfree(objp: vgadev);
820 return false;
821}
822
823static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
824{
825 struct vga_device *vgadev;
826 unsigned long flags;
827 bool ret = true;
828
829 spin_lock_irqsave(&vga_lock, flags);
830 vgadev = vgadev_find(pdev);
831 if (vgadev == NULL) {
832 ret = false;
833 goto bail;
834 }
835
836 if (vga_default == pdev)
837 vga_set_default_device(NULL);
838
839 if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
840 vga_decode_count--;
841
842 /* Remove entry from list */
843 list_del(entry: &vgadev->list);
844 vga_count--;
845
846 /* Wake up all possible waiters */
847 wake_up_all(&vga_wait_queue);
848bail:
849 spin_unlock_irqrestore(lock: &vga_lock, flags);
850 kfree(objp: vgadev);
851 return ret;
852}
853
854/* Called with the lock */
855static void vga_update_device_decodes(struct vga_device *vgadev,
856 unsigned int new_decodes)
857{
858 struct device *dev = &vgadev->pdev->dev;
859 unsigned int old_decodes = vgadev->decodes;
860 unsigned int decodes_removed = ~new_decodes & old_decodes;
861 unsigned int decodes_unlocked = vgadev->locks & decodes_removed;
862
863 vgadev->decodes = new_decodes;
864
865 vgaarb_info(dev, "VGA decodes changed: olddecodes=%s,decodes=%s:owns=%s\n",
866 vga_iostate_to_str(old_decodes),
867 vga_iostate_to_str(vgadev->decodes),
868 vga_iostate_to_str(vgadev->owns));
869
870 /* If we removed locked decodes, lock count goes to zero, and release */
871 if (decodes_unlocked) {
872 if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
873 vgadev->io_lock_cnt = 0;
874 if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
875 vgadev->mem_lock_cnt = 0;
876 __vga_put(vgadev, rsrc: decodes_unlocked);
877 }
878
879 /* Change decodes counter */
880 if (old_decodes & VGA_RSRC_LEGACY_MASK &&
881 !(new_decodes & VGA_RSRC_LEGACY_MASK))
882 vga_decode_count--;
883 if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
884 new_decodes & VGA_RSRC_LEGACY_MASK)
885 vga_decode_count++;
886 vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
887}
888
889static void __vga_set_legacy_decoding(struct pci_dev *pdev,
890 unsigned int decodes,
891 bool userspace)
892{
893 struct vga_device *vgadev;
894 unsigned long flags;
895
896 decodes &= VGA_RSRC_LEGACY_MASK;
897
898 spin_lock_irqsave(&vga_lock, flags);
899 vgadev = vgadev_find(pdev);
900 if (vgadev == NULL)
901 goto bail;
902
903 /* Don't let userspace futz with kernel driver decodes */
904 if (userspace && vgadev->set_decode)
905 goto bail;
906
907 /* Update the device decodes + counter */
908 vga_update_device_decodes(vgadev, new_decodes: decodes);
909
910 /*
911 * XXX If somebody is going from "doesn't decode" to "decodes"
912 * state here, additional care must be taken as we may have pending
913 * ownership of non-legacy region.
914 */
915bail:
916 spin_unlock_irqrestore(lock: &vga_lock, flags);
917}
918
919/**
920 * vga_set_legacy_decoding
921 * @pdev: PCI device of the VGA card
922 * @decodes: bit mask of what legacy regions the card decodes
923 *
924 * Indicate to the arbiter if the card decodes legacy VGA IOs, legacy VGA
925 * Memory, both, or none. All cards default to both, the card driver (fbdev for
926 * example) should tell the arbiter if it has disabled legacy decoding, so the
927 * card can be left out of the arbitration process (and can be safe to take
928 * interrupts at any time.
929 */
930void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
931{
932 __vga_set_legacy_decoding(pdev, decodes, userspace: false);
933}
934EXPORT_SYMBOL(vga_set_legacy_decoding);
935
936/**
937 * vga_client_register - register or unregister a VGA arbitration client
938 * @pdev: PCI device of the VGA client
939 * @set_decode: VGA decode change callback
940 *
941 * Clients have two callback mechanisms they can use.
942 *
943 * @set_decode callback: If a client can disable its GPU VGA resource, it
944 * will get a callback from this to set the encode/decode state.
945 *
946 * Rationale: we cannot disable VGA decode resources unconditionally
947 * because some single GPU laptops seem to require ACPI or BIOS access to
948 * the VGA registers to control things like backlights etc. Hopefully newer
949 * multi-GPU laptops do something saner, and desktops won't have any
950 * special ACPI for this. The driver will get a callback when VGA
951 * arbitration is first used by userspace since some older X servers have
952 * issues.
953 *
954 * Does not check whether a client for @pdev has been registered already.
955 *
956 * To unregister, call vga_client_unregister().
957 *
958 * Returns: 0 on success, -ENODEV on failure
959 */
960int vga_client_register(struct pci_dev *pdev,
961 unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
962{
963 unsigned long flags;
964 struct vga_device *vgadev;
965
966 spin_lock_irqsave(&vga_lock, flags);
967 vgadev = vgadev_find(pdev);
968 if (vgadev)
969 vgadev->set_decode = set_decode;
970 spin_unlock_irqrestore(lock: &vga_lock, flags);
971 if (!vgadev)
972 return -ENODEV;
973 return 0;
974}
975EXPORT_SYMBOL(vga_client_register);
976
977/*
978 * Char driver implementation
979 *
980 * Semantics is:
981 *
982 * open : Open user instance of the arbiter. By default, it's
983 * attached to the default VGA device of the system.
984 *
985 * close : Close user instance, release locks
986 *
987 * read : Return a string indicating the status of the target.
988 * An IO state string is of the form {io,mem,io+mem,none},
989 * mc and ic are respectively mem and io lock counts (for
990 * debugging/diagnostic only). "decodes" indicate what the
991 * card currently decodes, "owns" indicates what is currently
992 * enabled on it, and "locks" indicates what is locked by this
993 * card. If the card is unplugged, we get "invalid" then for
994 * card_ID and an -ENODEV error is returned for any command
995 * until a new card is targeted
996 *
997 * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
998 *
999 * write : write a command to the arbiter. List of commands is:
1000 *
1001 * target <card_ID> : switch target to card <card_ID> (see below)
1002 * lock <io_state> : acquire locks on target ("none" is invalid io_state)
1003 * trylock <io_state> : non-blocking acquire locks on target
1004 * unlock <io_state> : release locks on target
1005 * unlock all : release all locks on target held by this user
1006 * decodes <io_state> : set the legacy decoding attributes for the card
1007 *
1008 * poll : event if something change on any card (not just the target)
1009 *
1010 * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
1011 * to go back to the system default card (TODO: not implemented yet).
1012 * Currently, only PCI is supported as a prefix, but the userland API may
1013 * support other bus types in the future, even if the current kernel
1014 * implementation doesn't.
1015 *
1016 * Note about locks:
1017 *
1018 * The driver keeps track of which user has what locks on which card. It
1019 * supports stacking, like the kernel one. This complicates the implementation
1020 * a bit, but makes the arbiter more tolerant to userspace problems and able
1021 * to properly cleanup in all cases when a process dies.
1022 * Currently, a max of 16 cards simultaneously can have locks issued from
1023 * userspace for a given user (file descriptor instance) of the arbiter.
1024 *
1025 * If the device is hot-unplugged, there is a hook inside the module to notify
1026 * it being added/removed in the system and automatically added/removed in
1027 * the arbiter.
1028 */
1029
1030#define MAX_USER_CARDS CONFIG_VGA_ARB_MAX_GPUS
1031#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
1032
1033/* Each user has an array of these, tracking which cards have locks */
1034struct vga_arb_user_card {
1035 struct pci_dev *pdev;
1036 unsigned int mem_cnt;
1037 unsigned int io_cnt;
1038};
1039
1040struct vga_arb_private {
1041 struct list_head list;
1042 struct pci_dev *target;
1043 struct vga_arb_user_card cards[MAX_USER_CARDS];
1044 spinlock_t lock;
1045};
1046
1047static LIST_HEAD(vga_user_list);
1048static DEFINE_SPINLOCK(vga_user_lock);
1049
1050
1051/*
1052 * Take a string in the format: "PCI:domain:bus:dev.fn" and return the
1053 * respective values. If the string is not in this format, return 0.
1054 */
1055static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
1056 unsigned int *bus, unsigned int *devfn)
1057{
1058 int n;
1059 unsigned int slot, func;
1060
1061 n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
1062 if (n != 4)
1063 return 0;
1064
1065 *devfn = PCI_DEVFN(slot, func);
1066
1067 return 1;
1068}
1069
1070static ssize_t vga_arb_read(struct file *file, char __user *buf,
1071 size_t count, loff_t *ppos)
1072{
1073 struct vga_arb_private *priv = file->private_data;
1074 struct vga_device *vgadev;
1075 struct pci_dev *pdev;
1076 unsigned long flags;
1077 size_t len;
1078 int rc;
1079 char *lbuf;
1080
1081 lbuf = kmalloc(1024, GFP_KERNEL);
1082 if (lbuf == NULL)
1083 return -ENOMEM;
1084
1085 /* Protect vga_list */
1086 spin_lock_irqsave(&vga_lock, flags);
1087
1088 /* If we are targeting the default, use it */
1089 pdev = priv->target;
1090 if (pdev == NULL || pdev == PCI_INVALID_CARD) {
1091 spin_unlock_irqrestore(lock: &vga_lock, flags);
1092 len = sprintf(buf: lbuf, fmt: "invalid");
1093 goto done;
1094 }
1095
1096 /* Find card vgadev structure */
1097 vgadev = vgadev_find(pdev);
1098 if (vgadev == NULL) {
1099 /*
1100 * Wow, it's not in the list, that shouldn't happen, let's
1101 * fix us up and return invalid card.
1102 */
1103 spin_unlock_irqrestore(lock: &vga_lock, flags);
1104 len = sprintf(buf: lbuf, fmt: "invalid");
1105 goto done;
1106 }
1107
1108 /* Fill the buffer with info */
1109 len = snprintf(buf: lbuf, size: 1024,
1110 fmt: "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%u:%u)\n",
1111 vga_decode_count, pci_name(pdev),
1112 vga_iostate_to_str(iostate: vgadev->decodes),
1113 vga_iostate_to_str(iostate: vgadev->owns),
1114 vga_iostate_to_str(iostate: vgadev->locks),
1115 vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
1116
1117 spin_unlock_irqrestore(lock: &vga_lock, flags);
1118done:
1119
1120 /* Copy that to user */
1121 if (len > count)
1122 len = count;
1123 rc = copy_to_user(to: buf, from: lbuf, n: len);
1124 kfree(objp: lbuf);
1125 if (rc)
1126 return -EFAULT;
1127 return len;
1128}
1129
1130/*
1131 * TODO: To avoid parsing inside kernel and to improve the speed we may
1132 * consider use ioctl here
1133 */
1134static ssize_t vga_arb_write(struct file *file, const char __user *buf,
1135 size_t count, loff_t *ppos)
1136{
1137 struct vga_arb_private *priv = file->private_data;
1138 struct vga_arb_user_card *uc = NULL;
1139 struct pci_dev *pdev;
1140
1141 unsigned int io_state;
1142
1143 char kbuf[64], *curr_pos;
1144 size_t remaining = count;
1145
1146 int ret_val;
1147 int i;
1148
1149 if (count >= sizeof(kbuf))
1150 return -EINVAL;
1151 if (copy_from_user(to: kbuf, from: buf, n: count))
1152 return -EFAULT;
1153 curr_pos = kbuf;
1154 kbuf[count] = '\0';
1155
1156 if (strncmp(curr_pos, "lock ", 5) == 0) {
1157 curr_pos += 5;
1158 remaining -= 5;
1159
1160 pr_debug("client 0x%p called 'lock'\n", priv);
1161
1162 if (!vga_str_to_iostate(buf: curr_pos, str_size: remaining, io_state: &io_state)) {
1163 ret_val = -EPROTO;
1164 goto done;
1165 }
1166 if (io_state == VGA_RSRC_NONE) {
1167 ret_val = -EPROTO;
1168 goto done;
1169 }
1170
1171 pdev = priv->target;
1172 if (priv->target == NULL) {
1173 ret_val = -ENODEV;
1174 goto done;
1175 }
1176
1177 vga_get_uninterruptible(pdev, rsrc: io_state);
1178
1179 /* Update the client's locks lists */
1180 for (i = 0; i < MAX_USER_CARDS; i++) {
1181 if (priv->cards[i].pdev == pdev) {
1182 if (io_state & VGA_RSRC_LEGACY_IO)
1183 priv->cards[i].io_cnt++;
1184 if (io_state & VGA_RSRC_LEGACY_MEM)
1185 priv->cards[i].mem_cnt++;
1186 break;
1187 }
1188 }
1189
1190 ret_val = count;
1191 goto done;
1192 } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
1193 curr_pos += 7;
1194 remaining -= 7;
1195
1196 pr_debug("client 0x%p called 'unlock'\n", priv);
1197
1198 if (strncmp(curr_pos, "all", 3) == 0)
1199 io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
1200 else {
1201 if (!vga_str_to_iostate
1202 (buf: curr_pos, str_size: remaining, io_state: &io_state)) {
1203 ret_val = -EPROTO;
1204 goto done;
1205 }
1206 /* TODO: Add this?
1207 if (io_state == VGA_RSRC_NONE) {
1208 ret_val = -EPROTO;
1209 goto done;
1210 }
1211 */
1212 }
1213
1214 pdev = priv->target;
1215 if (priv->target == NULL) {
1216 ret_val = -ENODEV;
1217 goto done;
1218 }
1219 for (i = 0; i < MAX_USER_CARDS; i++) {
1220 if (priv->cards[i].pdev == pdev)
1221 uc = &priv->cards[i];
1222 }
1223
1224 if (!uc) {
1225 ret_val = -EINVAL;
1226 goto done;
1227 }
1228
1229 if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {
1230 ret_val = -EINVAL;
1231 goto done;
1232 }
1233
1234 if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {
1235 ret_val = -EINVAL;
1236 goto done;
1237 }
1238
1239 vga_put(pdev, io_state);
1240
1241 if (io_state & VGA_RSRC_LEGACY_IO)
1242 uc->io_cnt--;
1243 if (io_state & VGA_RSRC_LEGACY_MEM)
1244 uc->mem_cnt--;
1245
1246 ret_val = count;
1247 goto done;
1248 } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
1249 curr_pos += 8;
1250 remaining -= 8;
1251
1252 pr_debug("client 0x%p called 'trylock'\n", priv);
1253
1254 if (!vga_str_to_iostate(buf: curr_pos, str_size: remaining, io_state: &io_state)) {
1255 ret_val = -EPROTO;
1256 goto done;
1257 }
1258 /* TODO: Add this?
1259 if (io_state == VGA_RSRC_NONE) {
1260 ret_val = -EPROTO;
1261 goto done;
1262 }
1263 */
1264
1265 pdev = priv->target;
1266 if (priv->target == NULL) {
1267 ret_val = -ENODEV;
1268 goto done;
1269 }
1270
1271 if (vga_tryget(pdev, rsrc: io_state)) {
1272 /* Update the client's locks lists... */
1273 for (i = 0; i < MAX_USER_CARDS; i++) {
1274 if (priv->cards[i].pdev == pdev) {
1275 if (io_state & VGA_RSRC_LEGACY_IO)
1276 priv->cards[i].io_cnt++;
1277 if (io_state & VGA_RSRC_LEGACY_MEM)
1278 priv->cards[i].mem_cnt++;
1279 break;
1280 }
1281 }
1282 ret_val = count;
1283 goto done;
1284 } else {
1285 ret_val = -EBUSY;
1286 goto done;
1287 }
1288
1289 } else if (strncmp(curr_pos, "target ", 7) == 0) {
1290 unsigned int domain, bus, devfn;
1291 struct vga_device *vgadev;
1292
1293 curr_pos += 7;
1294 remaining -= 7;
1295 pr_debug("client 0x%p called 'target'\n", priv);
1296 /* If target is default */
1297 if (!strncmp(curr_pos, "default", 7))
1298 pdev = pci_dev_get(dev: vga_default_device());
1299 else {
1300 if (!vga_pci_str_to_vars(buf: curr_pos, count: remaining,
1301 domain: &domain, bus: &bus, devfn: &devfn)) {
1302 ret_val = -EPROTO;
1303 goto done;
1304 }
1305 pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
1306 if (!pdev) {
1307 pr_debug("invalid PCI address %04x:%02x:%02x.%x\n",
1308 domain, bus, PCI_SLOT(devfn),
1309 PCI_FUNC(devfn));
1310 ret_val = -ENODEV;
1311 goto done;
1312 }
1313
1314 pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos,
1315 domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
1316 pdev);
1317 }
1318
1319 vgadev = vgadev_find(pdev);
1320 pr_debug("vgadev %p\n", vgadev);
1321 if (vgadev == NULL) {
1322 if (pdev) {
1323 vgaarb_dbg(&pdev->dev, "not a VGA device\n");
1324 pci_dev_put(dev: pdev);
1325 }
1326
1327 ret_val = -ENODEV;
1328 goto done;
1329 }
1330
1331 priv->target = pdev;
1332 for (i = 0; i < MAX_USER_CARDS; i++) {
1333 if (priv->cards[i].pdev == pdev)
1334 break;
1335 if (priv->cards[i].pdev == NULL) {
1336 priv->cards[i].pdev = pdev;
1337 priv->cards[i].io_cnt = 0;
1338 priv->cards[i].mem_cnt = 0;
1339 break;
1340 }
1341 }
1342 if (i == MAX_USER_CARDS) {
1343 vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",
1344 MAX_USER_CARDS);
1345 pci_dev_put(dev: pdev);
1346 /* XXX: Which value to return? */
1347 ret_val = -ENOMEM;
1348 goto done;
1349 }
1350
1351 ret_val = count;
1352 pci_dev_put(dev: pdev);
1353 goto done;
1354
1355
1356 } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
1357 curr_pos += 8;
1358 remaining -= 8;
1359 pr_debug("client 0x%p called 'decodes'\n", priv);
1360
1361 if (!vga_str_to_iostate(buf: curr_pos, str_size: remaining, io_state: &io_state)) {
1362 ret_val = -EPROTO;
1363 goto done;
1364 }
1365 pdev = priv->target;
1366 if (priv->target == NULL) {
1367 ret_val = -ENODEV;
1368 goto done;
1369 }
1370
1371 __vga_set_legacy_decoding(pdev, decodes: io_state, userspace: true);
1372 ret_val = count;
1373 goto done;
1374 }
1375 /* If we got here, the message written is not part of the protocol! */
1376 return -EPROTO;
1377
1378done:
1379 return ret_val;
1380}
1381
1382static __poll_t vga_arb_fpoll(struct file *file, poll_table *wait)
1383{
1384 pr_debug("%s\n", __func__);
1385
1386 poll_wait(filp: file, wait_address: &vga_wait_queue, p: wait);
1387 return EPOLLIN;
1388}
1389
1390static int vga_arb_open(struct inode *inode, struct file *file)
1391{
1392 struct vga_arb_private *priv;
1393 unsigned long flags;
1394
1395 pr_debug("%s\n", __func__);
1396
1397 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1398 if (priv == NULL)
1399 return -ENOMEM;
1400 spin_lock_init(&priv->lock);
1401 file->private_data = priv;
1402
1403 spin_lock_irqsave(&vga_user_lock, flags);
1404 list_add(new: &priv->list, head: &vga_user_list);
1405 spin_unlock_irqrestore(lock: &vga_user_lock, flags);
1406
1407 /* Set the client's lists of locks */
1408 priv->target = vga_default_device(); /* Maybe this is still null! */
1409 priv->cards[0].pdev = priv->target;
1410 priv->cards[0].io_cnt = 0;
1411 priv->cards[0].mem_cnt = 0;
1412
1413 return 0;
1414}
1415
1416static int vga_arb_release(struct inode *inode, struct file *file)
1417{
1418 struct vga_arb_private *priv = file->private_data;
1419 struct vga_arb_user_card *uc;
1420 unsigned long flags;
1421 int i;
1422
1423 pr_debug("%s\n", __func__);
1424
1425 spin_lock_irqsave(&vga_user_lock, flags);
1426 list_del(entry: &priv->list);
1427 for (i = 0; i < MAX_USER_CARDS; i++) {
1428 uc = &priv->cards[i];
1429 if (uc->pdev == NULL)
1430 continue;
1431 vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",
1432 uc->io_cnt, uc->mem_cnt);
1433 while (uc->io_cnt--)
1434 vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
1435 while (uc->mem_cnt--)
1436 vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
1437 }
1438 spin_unlock_irqrestore(lock: &vga_user_lock, flags);
1439
1440 kfree(objp: priv);
1441
1442 return 0;
1443}
1444
1445/*
1446 * Callback any registered clients to let them know we have a change in VGA
1447 * cards.
1448 */
1449static void vga_arbiter_notify_clients(void)
1450{
1451 struct vga_device *vgadev;
1452 unsigned long flags;
1453 unsigned int new_decodes;
1454 bool new_state;
1455
1456 if (!vga_arbiter_used)
1457 return;
1458
1459 new_state = (vga_count > 1) ? false : true;
1460
1461 spin_lock_irqsave(&vga_lock, flags);
1462 list_for_each_entry(vgadev, &vga_list, list) {
1463 if (vgadev->set_decode) {
1464 new_decodes = vgadev->set_decode(vgadev->pdev,
1465 new_state);
1466 vga_update_device_decodes(vgadev, new_decodes);
1467 }
1468 }
1469 spin_unlock_irqrestore(lock: &vga_lock, flags);
1470}
1471
1472static int pci_notify(struct notifier_block *nb, unsigned long action,
1473 void *data)
1474{
1475 struct device *dev = data;
1476 struct pci_dev *pdev = to_pci_dev(dev);
1477 bool notify = false;
1478
1479 vgaarb_dbg(dev, "%s\n", __func__);
1480
1481 /* Only deal with VGA class devices */
1482 if (!pci_is_vga(pdev))
1483 return 0;
1484
1485 /*
1486 * For now, we're only interested in devices added and removed.
1487 * I didn't test this thing here, so someone needs to double check
1488 * for the cases of hot-pluggable VGA cards.
1489 */
1490 if (action == BUS_NOTIFY_ADD_DEVICE)
1491 notify = vga_arbiter_add_pci_device(pdev);
1492 else if (action == BUS_NOTIFY_DEL_DEVICE)
1493 notify = vga_arbiter_del_pci_device(pdev);
1494
1495 if (notify)
1496 vga_arbiter_notify_clients();
1497 return 0;
1498}
1499
1500static struct notifier_block pci_notifier = {
1501 .notifier_call = pci_notify,
1502};
1503
1504static const struct file_operations vga_arb_device_fops = {
1505 .read = vga_arb_read,
1506 .write = vga_arb_write,
1507 .poll = vga_arb_fpoll,
1508 .open = vga_arb_open,
1509 .release = vga_arb_release,
1510 .llseek = noop_llseek,
1511};
1512
1513static struct miscdevice vga_arb_device = {
1514 MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
1515};
1516
1517static int __init vga_arb_device_init(void)
1518{
1519 int rc;
1520 struct pci_dev *pdev;
1521
1522 rc = misc_register(misc: &vga_arb_device);
1523 if (rc < 0)
1524 pr_err("error %d registering device\n", rc);
1525
1526 bus_register_notifier(bus: &pci_bus_type, nb: &pci_notifier);
1527
1528 /* Add all VGA class PCI devices by default */
1529 pdev = NULL;
1530 while ((pdev =
1531 pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
1532 PCI_ANY_ID, from: pdev)) != NULL) {
1533 if (pci_is_vga(pdev))
1534 vga_arbiter_add_pci_device(pdev);
1535 }
1536
1537 pr_info("loaded\n");
1538 return rc;
1539}
1540subsys_initcall_sync(vga_arb_device_init);
1541