1 // SPDX-License-Identifier: MIT
3  * vgaarb.c: Implements the VGA arbitration. For details refer to
40  * We keep a list of all vga devices in the system to speed
102 /* this is only used a cookie - it should not be dereferenced */
111 		if (pdev == vgadev->pdev)  in vgadev_find()
117  * vga_default_device - return the default VGA device, for vgacon
121  * vga card setups and/or x86 platforms.
123  * If your VGA default device is not PCI, you'll have to return
126  * hooks for enabling/disabling the VGA default device if that is
127  * possible. This may be a problem with real _ISA_ VGA cards, in
150  * vga_remove_vgacon - deactivete vga console
152  * Unbind and unregister vgacon in case pdev is the default vga
154  * sure vga register access done by vgacon will not disturb the
167 	return -ENODEV;  in vga_remove_vgacon()
176 	vgaarb_info(&pdev->dev, "deactivate vga console\n");  in vga_remove_vgacon()
181 					   MAX_NR_CONSOLES - 1, 1);  in vga_remove_vgacon()
186 		if (ret == -ENODEV)  in vga_remove_vgacon()
196 /* If we don't ever use VGA arb we should avoid
198    confused about the boot device not being VGA */
202 	 * VGA arb has occurred and to try and disable resources  in vga_check_first_use()
213 	struct device *dev = &vgadev->pdev->dev;  in __vga_tryget()
223 	    (vgadev->decodes & VGA_RSRC_LEGACY_IO))  in __vga_tryget()
226 	    (vgadev->decodes & VGA_RSRC_LEGACY_MEM))  in __vga_tryget()
230 	vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns);  in __vga_tryget()
233 	wants = rsrc & ~vgadev->owns;  in __vga_tryget()
259 		 * VGA forwarding on P2P bridges  in __vga_tryget()
261 		if (vgadev->pdev->bus != conflict->pdev->bus) {  in __vga_tryget()
269 		if (conflict->locks & lwants)  in __vga_tryget()
276 		match = lwants & conflict->owns;  in __vga_tryget()
290 		if (!conflict->bridge_has_one_vga) {  in __vga_tryget()
291 			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)  in __vga_tryget()
293 			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)  in __vga_tryget()
303 		pci_set_vga_state(conflict->pdev, false, pci_bits, flags);  in __vga_tryget()
304 		conflict->owns &= ~match;  in __vga_tryget()
308 			conflict->owns &= ~VGA_RSRC_NORMAL_MEM;  in __vga_tryget()
310 			conflict->owns &= ~VGA_RSRC_NORMAL_IO;  in __vga_tryget()
322 	if (!vgadev->bridge_has_one_vga) {  in __vga_tryget()
332 	pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);  in __vga_tryget()
334 	vgadev->owns |= wants;  in __vga_tryget()
336 	vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);  in __vga_tryget()
338 		vgadev->io_lock_cnt++;  in __vga_tryget()
340 		vgadev->mem_lock_cnt++;  in __vga_tryget()
342 		vgadev->io_norm_cnt++;  in __vga_tryget()
344 		vgadev->mem_norm_cnt++;  in __vga_tryget()
351 	struct device *dev = &vgadev->pdev->dev;  in __vga_put()
352 	unsigned int old_locks = vgadev->locks;  in __vga_put()
359 	if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {  in __vga_put()
360 		vgadev->io_norm_cnt--;  in __vga_put()
361 		if (vgadev->decodes & VGA_RSRC_LEGACY_IO)  in __vga_put()
364 	if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {  in __vga_put()
365 		vgadev->mem_norm_cnt--;  in __vga_put()
366 		if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)  in __vga_put()
369 	if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)  in __vga_put()
370 		vgadev->io_lock_cnt--;  in __vga_put()
371 	if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)  in __vga_put()
372 		vgadev->mem_lock_cnt--;  in __vga_put()
377 	if (vgadev->io_lock_cnt == 0)  in __vga_put()
378 		vgadev->locks &= ~VGA_RSRC_LEGACY_IO;  in __vga_put()
379 	if (vgadev->mem_lock_cnt == 0)  in __vga_put()
380 		vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;  in __vga_put()
385 	if (old_locks != vgadev->locks)  in __vga_put()
390  * vga_get - acquire & locks VGA resources
391  * @pdev: pci device of the VGA card or NULL for the system default
395  * This function acquires VGA resources for the given card and mark those
401  * The arbiter will first look for all VGA cards that might conflict and disable
402  * their IOs and/or Memory access, including VGA forwarding on P2P bridges if
405  * enabled on the card (including VGA forwarding on parent P2P bridges if any).
409  * bridges don't differentiate VGA memory and IO afaik). You can indicate
415  * supported (a per-resource counter is maintained)
417  * On success, release the VGA resource again with vga_put().
442 			rc = -ENODEV;  in vga_get()
465 			rc = -ERESTARTSYS;  in vga_get()
476  * vga_tryget - try to acquire & lock legacy VGA resources
477  * @pdev: pci devivce of VGA card or NULL for system default
481  * error (-EBUSY) instead of blocking if the resources are already locked by
484  * On success, release the VGA resource again with vga_put().
506 		rc = -ENODEV;  in vga_tryget()
510 		rc = -EBUSY;  in vga_tryget()
517  * vga_put - release lock on legacy VGA resources
518  * @pdev: pci device of VGA card or NULL for system default
597  * Return true if vgadev is a better default VGA device than the best one
603 	struct pci_dev *pdev = vgadev->pdev;  in vga_is_boot_device()
607 	 * We select the default VGA device in this order:  in vga_is_boot_device()
609 	 *   Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)  in vga_is_boot_device()
610 	 *   Non-legacy integrated device (see vga_arb_select_default_device())  in vga_is_boot_device()
611 	 *   Non-legacy discrete device (see vga_arb_select_default_device())  in vga_is_boot_device()
619 	if (boot_vga && boot_vga->is_firmware_default)  in vga_is_boot_device()
623 		vgadev->is_firmware_default = true;  in vga_is_boot_device()
628 	 * A legacy VGA device has MEM and IO enabled and any bridges  in vga_is_boot_device()
630 	 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are  in vga_is_boot_device()
637 	    (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)  in vga_is_boot_device()
640 	if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)  in vga_is_boot_device()
644 	 * If we haven't found a legacy VGA device, accept a non-legacy  in vga_is_boot_device()
647 	 * use legacy VGA resources.  Prefer an integrated GPU over others.  in vga_is_boot_device()
653 		 * An integrated GPU overrides a previous non-legacy  in vga_is_boot_device()
658 		if (vga_arb_integrated_gpu(&pdev->dev))  in vga_is_boot_device()
662 		 * We prefer the first non-legacy discrete device we find.  in vga_is_boot_device()
666 			pci_read_config_word(boot_vga->pdev, PCI_COMMAND,  in vga_is_boot_device()
676 	 * other VGA devices, it is the best candidate so far.  in vga_is_boot_device()
685  * Rules for using a bridge to control a VGA descendant decoding: if a bridge
686  * has only one VGA descendant then it can be used to control the VGA routing
688  * control it. If a bridge has a direct VGA descendant, but also have a sub-
689  * bridge VGA descendant then we cannot use that bridge to control the direct
690  * VGA descendant. So for every device we register, we need to iterate all
699 	vgadev->bridge_has_one_vga = true;  in vga_arbiter_check_bridge_sharing()
702 		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");  in vga_arbiter_check_bridge_sharing()
707 	new_bus = vgadev->pdev->bus;  in vga_arbiter_check_bridge_sharing()
709 		new_bridge = new_bus->self;  in vga_arbiter_check_bridge_sharing()
713 			bus = same_bridge_vgadev->pdev->bus;  in vga_arbiter_check_bridge_sharing()
714 			bridge = bus->self;  in vga_arbiter_check_bridge_sharing()
723 				same_bridge_vgadev->bridge_has_one_vga = false;  in vga_arbiter_check_bridge_sharing()
733 				bridge = bus->self;  in vga_arbiter_check_bridge_sharing()
735 				if (bridge && bridge == vgadev->pdev->bus->self)  in vga_arbiter_check_bridge_sharing()
736 					vgadev->bridge_has_one_vga = false;  in vga_arbiter_check_bridge_sharing()
738 				bus = bus->parent;  in vga_arbiter_check_bridge_sharing()
741 		new_bus = new_bus->parent;  in vga_arbiter_check_bridge_sharing()
744 	if (vgadev->bridge_has_one_vga)  in vga_arbiter_check_bridge_sharing()
745 		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");  in vga_arbiter_check_bridge_sharing()
747 		vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");  in vga_arbiter_check_bridge_sharing()
764 	/* Only deal with VGA class devices */  in vga_arbiter_add_pci_device()
765 	if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)  in vga_arbiter_add_pci_device()
771 		vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");  in vga_arbiter_add_pci_device()
785 	vgadev->pdev = pdev;  in vga_arbiter_add_pci_device()
788 	vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |  in vga_arbiter_add_pci_device()
798 		vgadev->owns |= VGA_RSRC_LEGACY_IO;  in vga_arbiter_add_pci_device()
800 		vgadev->owns |= VGA_RSRC_LEGACY_MEM;  in vga_arbiter_add_pci_device()
802 	/* Check if VGA cycles can get down to us */  in vga_arbiter_add_pci_device()
803 	bus = pdev->bus;  in vga_arbiter_add_pci_device()
805 		bridge = bus->self;  in vga_arbiter_add_pci_device()
811 				vgadev->owns = 0;  in vga_arbiter_add_pci_device()
815 		bus = bus->parent;  in vga_arbiter_add_pci_device()
819 		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",  in vga_arbiter_add_pci_device()
828 	list_add_tail(&vgadev->list, &vga_list);  in vga_arbiter_add_pci_device()
830 	vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",  in vga_arbiter_add_pci_device()
831 		vga_iostate_to_str(vgadev->decodes),  in vga_arbiter_add_pci_device()
832 		vga_iostate_to_str(vgadev->owns),  in vga_arbiter_add_pci_device()
833 		vga_iostate_to_str(vgadev->locks));  in vga_arbiter_add_pci_device()
859 	if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))  in vga_arbiter_del_pci_device()
860 		vga_decode_count--;  in vga_arbiter_del_pci_device()
863 	list_del(&vgadev->list);  in vga_arbiter_del_pci_device()
864 	vga_count--;  in vga_arbiter_del_pci_device()
878 	struct device *dev = &vgadev->pdev->dev;  in vga_update_device_decodes()
881 	old_decodes = vgadev->decodes;  in vga_update_device_decodes()
883 	decodes_unlocked = vgadev->locks & decodes_removed;  in vga_update_device_decodes()
884 	vgadev->decodes = new_decodes;  in vga_update_device_decodes()
886 	vgaarb_info(dev, "changed VGA decodes: olddecodes=%s,decodes=%s:owns=%s\n",  in vga_update_device_decodes()
888 		vga_iostate_to_str(vgadev->decodes),  in vga_update_device_decodes()
889 		vga_iostate_to_str(vgadev->owns));  in vga_update_device_decodes()
894 			vgadev->io_lock_cnt = 0;  in vga_update_device_decodes()
896 			vgadev->mem_lock_cnt = 0;  in vga_update_device_decodes()
903 		vga_decode_count--;  in vga_update_device_decodes()
925 	if (userspace && vgadev->set_decode)  in __vga_set_legacy_decoding()
933 	 * ship of non-legacy region ...  in __vga_set_legacy_decoding()
941  * @pdev: pci device of the VGA card
944  * Indicates to the arbiter if the card decodes legacy VGA IOs, legacy VGA
957  * vga_client_register - register or unregister a VGA arbitration client
958  * @pdev: pci device of the VGA client
959  * @set_decode: vga decode change callback
963  * @set_decode callback: If a client can disable its GPU VGA resource, it
966  * Rationale: we cannot disable VGA decode resources unconditionally some single
967  * GPU laptops seem to require ACPI or BIOS access to the VGA registers to
968  * control things like backlights etc.  Hopefully newer multi-GPU laptops do
970  * driver will get a callback when VGA arbitration is first used by userspace
978  * Returns: 0 on success, -1 on failure
983 	int ret = -ENODEV;  in vga_client_register()
992 	vgadev->set_decode = set_decode;  in vga_client_register()
1008  *                attached to the default VGA device of the system.
1019  *                card_ID and an -ENODEV error is returned for any command
1028  *   trylock <io_state> : non-blocking acquire locks on target
1050  * If the device is hot-unplugged, there is a hook inside the module to notify
1056 #define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
1079  * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
1080  * returns the respective values. If the string is not in this format,
1102 	struct vga_arb_private *priv = file->private_data;  in vga_arb_read()
1112 		return -ENOMEM;  in vga_arb_read()
1118 	pdev = priv->target;  in vga_arb_read()
1140 		       vga_iostate_to_str(vgadev->decodes),  in vga_arb_read()
1141 		       vga_iostate_to_str(vgadev->owns),  in vga_arb_read()
1142 		       vga_iostate_to_str(vgadev->locks),  in vga_arb_read()
1143 		       vgadev->io_lock_cnt, vgadev->mem_lock_cnt);  in vga_arb_read()
1154 		return -EFAULT;  in vga_arb_read()
1165 	struct vga_arb_private *priv = file->private_data;  in vga_arb_write()
1178 		return -EINVAL;  in vga_arb_write()
1180 		return -EFAULT;  in vga_arb_write()
1186 		remaining -= 5;  in vga_arb_write()
1191 			ret_val = -EPROTO;  in vga_arb_write()
1195 			ret_val = -EPROTO;  in vga_arb_write()
1199 		pdev = priv->target;  in vga_arb_write()
1200 		if (priv->target == NULL) {  in vga_arb_write()
1201 			ret_val = -ENODEV;  in vga_arb_write()
1209 			if (priv->cards[i].pdev == pdev) {  in vga_arb_write()
1211 					priv->cards[i].io_cnt++;  in vga_arb_write()
1213 					priv->cards[i].mem_cnt++;  in vga_arb_write()
1222 		remaining -= 7;  in vga_arb_write()
1231 				ret_val = -EPROTO;  in vga_arb_write()
1236 			   ret_val = -EPROTO;  in vga_arb_write()
1242 		pdev = priv->target;  in vga_arb_write()
1243 		if (priv->target == NULL) {  in vga_arb_write()
1244 			ret_val = -ENODEV;  in vga_arb_write()
1248 			if (priv->cards[i].pdev == pdev)  in vga_arb_write()
1249 				uc = &priv->cards[i];  in vga_arb_write()
1253 			ret_val = -EINVAL;  in vga_arb_write()
1257 		if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {  in vga_arb_write()
1258 			ret_val = -EINVAL;  in vga_arb_write()
1262 		if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {  in vga_arb_write()
1263 			ret_val = -EINVAL;  in vga_arb_write()
1270 			uc->io_cnt--;  in vga_arb_write()
1272 			uc->mem_cnt--;  in vga_arb_write()
1278 		remaining -= 8;  in vga_arb_write()
1283 			ret_val = -EPROTO;  in vga_arb_write()
1288 		   ret_val = -EPROTO;  in vga_arb_write()
1293 		pdev = priv->target;  in vga_arb_write()
1294 		if (priv->target == NULL) {  in vga_arb_write()
1295 			ret_val = -ENODEV;  in vga_arb_write()
1302 				if (priv->cards[i].pdev == pdev) {  in vga_arb_write()
1304 						priv->cards[i].io_cnt++;  in vga_arb_write()
1306 						priv->cards[i].mem_cnt++;  in vga_arb_write()
1313 			ret_val = -EBUSY;  in vga_arb_write()
1322 		remaining -= 7;  in vga_arb_write()
1330 				ret_val = -EPROTO;  in vga_arb_write()
1338 				ret_val = -ENODEV;  in vga_arb_write()
1351 				vgaarb_dbg(&pdev->dev, "not a VGA device\n");  in vga_arb_write()
1355 			ret_val = -ENODEV;  in vga_arb_write()
1359 		priv->target = pdev;  in vga_arb_write()
1361 			if (priv->cards[i].pdev == pdev)  in vga_arb_write()
1363 			if (priv->cards[i].pdev == NULL) {  in vga_arb_write()
1364 				priv->cards[i].pdev = pdev;  in vga_arb_write()
1365 				priv->cards[i].io_cnt = 0;  in vga_arb_write()
1366 				priv->cards[i].mem_cnt = 0;  in vga_arb_write()
1371 			vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",  in vga_arb_write()
1375 			ret_val =  -ENOMEM;  in vga_arb_write()
1386 		remaining -= 8;  in vga_arb_write()
1390 			ret_val = -EPROTO;  in vga_arb_write()
1393 		pdev = priv->target;  in vga_arb_write()
1394 		if (priv->target == NULL) {  in vga_arb_write()
1395 			ret_val = -ENODEV;  in vga_arb_write()
1404 	return -EPROTO;  in vga_arb_write()
1427 		return -ENOMEM;  in vga_arb_open()
1428 	spin_lock_init(&priv->lock);  in vga_arb_open()
1429 	file->private_data = priv;  in vga_arb_open()
1432 	list_add(&priv->list, &vga_user_list);  in vga_arb_open()
1436 	priv->target = vga_default_device(); /* Maybe this is still null! */  in vga_arb_open()
1437 	priv->cards[0].pdev = priv->target;  in vga_arb_open()
1438 	priv->cards[0].io_cnt = 0;  in vga_arb_open()
1439 	priv->cards[0].mem_cnt = 0;  in vga_arb_open()
1447 	struct vga_arb_private *priv = file->private_data;  in vga_arb_release()
1455 	list_del(&priv->list);  in vga_arb_release()
1457 		uc = &priv->cards[i];  in vga_arb_release()
1458 		if (uc->pdev == NULL)  in vga_arb_release()
1460 		vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",  in vga_arb_release()
1461 			uc->io_cnt, uc->mem_cnt);  in vga_arb_release()
1462 		while (uc->io_cnt--)  in vga_arb_release()
1463 			vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);  in vga_arb_release()
1464 		while (uc->mem_cnt--)  in vga_arb_release()
1465 			vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);  in vga_arb_release()
1476  * change in VGA cards
1494 		if (vgadev->set_decode) {  in vga_arbiter_notify_clients()
1495 			new_decodes = vgadev->set_decode(vgadev->pdev,  in vga_arbiter_notify_clients()
1514 	 * cases of hotplugable vga cards. */  in pci_notify()
1553 	/* We add all PCI devices satisfying VGA class in the arbiter by  in vga_arb_device_init()