1 // SPDX-License-Identifier: MIT
3  * vgaarb.c: Implements VGA arbitration. For details refer to
39  * We keep a list of all VGA devices in the system to speed
111 		if (pdev == vgadev->pdev)  in vgadev_find()
117  * vga_default_device - return the default VGA device, for vgacon
120  * rather dumb and will probably only work properly on single VGA card
123  * If your VGA default device is not PCI, you'll have to return NULL here.
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
148  * vga_remove_vgacon - deactivate VGA console
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
164 	return -ENODEV;  in vga_remove_vgacon()
173 	vgaarb_info(&pdev->dev, "deactivate vga console\n");  in vga_remove_vgacon()
178 					   MAX_NR_CONSOLES - 1, 1);  in vga_remove_vgacon()
183 		if (ret == -ENODEV)  in vga_remove_vgacon()
194  * If we don't ever use VGA arbitration, we should avoid turning off
196  * device not being VGA.
201 	 * Inform all GPUs in the system that VGA arbitration has occurred  in vga_check_first_use()
213 	struct device *dev = &vgadev->pdev->dev;  in __vga_tryget()
224 	    (vgadev->decodes & VGA_RSRC_LEGACY_IO))  in __vga_tryget()
227 	    (vgadev->decodes & VGA_RSRC_LEGACY_MEM))  in __vga_tryget()
231 	vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns);  in __vga_tryget()
234 	wants = rsrc & ~vgadev->owns;  in __vga_tryget()
262 		 * VGA forwarding on P2P bridges.  in __vga_tryget()
264 		if (vgadev->pdev->bus != conflict->pdev->bus) {  in __vga_tryget()
273 		if (conflict->locks & lwants)  in __vga_tryget()
281 		match = lwants & conflict->owns;  in __vga_tryget()
297 		if (!conflict->bridge_has_one_vga) {  in __vga_tryget()
298 			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)  in __vga_tryget()
300 			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)  in __vga_tryget()
310 		pci_set_vga_state(conflict->pdev, false, pci_bits, flags);  in __vga_tryget()
311 		conflict->owns &= ~match;  in __vga_tryget()
315 			conflict->owns &= ~VGA_RSRC_NORMAL_MEM;  in __vga_tryget()
317 			conflict->owns &= ~VGA_RSRC_NORMAL_IO;  in __vga_tryget()
330 	if (!vgadev->bridge_has_one_vga) {  in __vga_tryget()
340 	pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);  in __vga_tryget()
342 	vgadev->owns |= wants;  in __vga_tryget()
344 	vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);  in __vga_tryget()
346 		vgadev->io_lock_cnt++;  in __vga_tryget()
348 		vgadev->mem_lock_cnt++;  in __vga_tryget()
350 		vgadev->io_norm_cnt++;  in __vga_tryget()
352 		vgadev->mem_norm_cnt++;  in __vga_tryget()
359 	struct device *dev = &vgadev->pdev->dev;  in __vga_put()
360 	unsigned int old_locks = vgadev->locks;  in __vga_put()
368 	if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {  in __vga_put()
369 		vgadev->io_norm_cnt--;  in __vga_put()
370 		if (vgadev->decodes & VGA_RSRC_LEGACY_IO)  in __vga_put()
373 	if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {  in __vga_put()
374 		vgadev->mem_norm_cnt--;  in __vga_put()
375 		if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)  in __vga_put()
378 	if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)  in __vga_put()
379 		vgadev->io_lock_cnt--;  in __vga_put()
380 	if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)  in __vga_put()
381 		vgadev->mem_lock_cnt--;  in __vga_put()
387 	if (vgadev->io_lock_cnt == 0)  in __vga_put()
388 		vgadev->locks &= ~VGA_RSRC_LEGACY_IO;  in __vga_put()
389 	if (vgadev->mem_lock_cnt == 0)  in __vga_put()
390 		vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;  in __vga_put()
396 	if (old_locks != vgadev->locks)  in __vga_put()
401  * vga_get - acquire & lock VGA resources
402  * @pdev: PCI device of the VGA card or NULL for the system default
406  * Acquire VGA resources for the given card and mark those resources
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
416  * enabled on the card (including VGA forwarding on parent P2P bridges if any).
420  * bridges don't differentiate VGA memory and IO afaik). You can indicate
426  * supported (a per-resource counter is maintained)
428  * On success, release the VGA resource again with vga_put().
453 			rc = -ENODEV;  in vga_get()
465 		 * be fairly easy to have a per-device one so that we only  in vga_get()
476 			rc = -ERESTARTSYS;  in vga_get()
487  * vga_tryget - try to acquire & lock legacy VGA resources
488  * @pdev: PCI device of VGA card or NULL for system default
491  * Perform the same operation as vga_get(), but return an error (-EBUSY)
495  * On success, release the VGA resource again with vga_put().
517 		rc = -ENODEV;  in vga_tryget()
521 		rc = -EBUSY;  in vga_tryget()
528  * vga_put - release lock on legacy VGA resources
529  * @pdev: PCI device of VGA card or NULL for system default
577 		if (!r->start || !r->end)  in vga_is_firmware_default()
580 		if (base < r->start || limit >= r->end)  in vga_is_firmware_default()
601  * Return true if vgadev is a better default VGA device than the best one
607 	struct pci_dev *pdev = vgadev->pdev;  in vga_is_boot_device()
611 	 * We select the default VGA device in this order:  in vga_is_boot_device()
613 	 *   Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)  in vga_is_boot_device()
614 	 *   Non-legacy integrated device (see vga_arb_select_default_device())  in vga_is_boot_device()
615 	 *   Non-legacy discrete device (see vga_arb_select_default_device())  in vga_is_boot_device()
623 	if (boot_vga && boot_vga->is_firmware_default)  in vga_is_boot_device()
627 		vgadev->is_firmware_default = true;  in vga_is_boot_device()
632 	 * A legacy VGA device has MEM and IO enabled and any bridges  in vga_is_boot_device()
634 	 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are  in vga_is_boot_device()
641 	    (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)  in vga_is_boot_device()
644 	if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)  in vga_is_boot_device()
648 	 * If we haven't found a legacy VGA device, accept a non-legacy  in vga_is_boot_device()
651 	 * use legacy VGA resources.  Prefer an integrated GPU over others.  in vga_is_boot_device()
657 		 * An integrated GPU overrides a previous non-legacy  in vga_is_boot_device()
662 		if (vga_arb_integrated_gpu(&pdev->dev))  in vga_is_boot_device()
666 		 * We prefer the first non-legacy discrete device we find.  in vga_is_boot_device()
670 			pci_read_config_word(boot_vga->pdev, PCI_COMMAND,  in vga_is_boot_device()
680 	 * other VGA devices, it is the best candidate so far.  in vga_is_boot_device()
689  * Rules for using a bridge to control a VGA descendant decoding: if a bridge
690  * has only one VGA descendant then it can be used to control the VGA routing
692  * control it. If a bridge has a direct VGA descendant, but also have a sub-
693  * bridge VGA descendant then we cannot use that bridge to control the direct
694  * VGA descendant. So for every device we register, we need to iterate all
703 	vgadev->bridge_has_one_vga = true;  in vga_arbiter_check_bridge_sharing()
706 		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");  in vga_arbiter_check_bridge_sharing()
711 	new_bus = vgadev->pdev->bus;  in vga_arbiter_check_bridge_sharing()
713 		new_bridge = new_bus->self;  in vga_arbiter_check_bridge_sharing()
717 			bus = same_bridge_vgadev->pdev->bus;  in vga_arbiter_check_bridge_sharing()
718 			bridge = bus->self;  in vga_arbiter_check_bridge_sharing()
727 				same_bridge_vgadev->bridge_has_one_vga = false;  in vga_arbiter_check_bridge_sharing()
737 				bridge = bus->self;  in vga_arbiter_check_bridge_sharing()
739 				if (bridge && bridge == vgadev->pdev->bus->self)  in vga_arbiter_check_bridge_sharing()
740 					vgadev->bridge_has_one_vga = false;  in vga_arbiter_check_bridge_sharing()
742 				bus = bus->parent;  in vga_arbiter_check_bridge_sharing()
745 		new_bus = new_bus->parent;  in vga_arbiter_check_bridge_sharing()
748 	if (vgadev->bridge_has_one_vga)  in vga_arbiter_check_bridge_sharing()
749 		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");  in vga_arbiter_check_bridge_sharing()
751 		vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");  in vga_arbiter_check_bridge_sharing()
770 		vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");  in vga_arbiter_add_pci_device()
784 	vgadev->pdev = pdev;  in vga_arbiter_add_pci_device()
787 	vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |  in vga_arbiter_add_pci_device()
799 		vgadev->owns |= VGA_RSRC_LEGACY_IO;  in vga_arbiter_add_pci_device()
801 		vgadev->owns |= VGA_RSRC_LEGACY_MEM;  in vga_arbiter_add_pci_device()
803 	/* Check if VGA cycles can get down to us */  in vga_arbiter_add_pci_device()
804 	bus = pdev->bus;  in vga_arbiter_add_pci_device()
806 		bridge = bus->self;  in vga_arbiter_add_pci_device()
812 				vgadev->owns = 0;  in vga_arbiter_add_pci_device()
816 		bus = bus->parent;  in vga_arbiter_add_pci_device()
820 		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",  in vga_arbiter_add_pci_device()
829 	list_add_tail(&vgadev->list, &vga_list);  in vga_arbiter_add_pci_device()
831 	vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",  in vga_arbiter_add_pci_device()
832 		vga_iostate_to_str(vgadev->decodes),  in vga_arbiter_add_pci_device()
833 		vga_iostate_to_str(vgadev->owns),  in vga_arbiter_add_pci_device()
834 		vga_iostate_to_str(vgadev->locks));  in vga_arbiter_add_pci_device()
860 	if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))  in vga_arbiter_del_pci_device()
861 		vga_decode_count--;  in vga_arbiter_del_pci_device()
864 	list_del(&vgadev->list);  in vga_arbiter_del_pci_device()
865 	vga_count--;  in vga_arbiter_del_pci_device()
879 	struct device *dev = &vgadev->pdev->dev;  in vga_update_device_decodes()
880 	unsigned int old_decodes = vgadev->decodes;  in vga_update_device_decodes()
882 	unsigned int 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, "VGA decodes changed: 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()
934 	 * ownership of non-legacy region.  in __vga_set_legacy_decoding()
942  * @pdev: PCI device of the VGA card
945  * Indicate to the arbiter if the card decodes legacy VGA IOs, legacy VGA
958  * vga_client_register - register or unregister a VGA arbitration client
959  * @pdev: PCI device of the VGA client
960  * @set_decode: VGA decode change callback
964  * @set_decode callback: If a client can disable its GPU VGA resource, it
967  * Rationale: we cannot disable VGA decode resources unconditionally
969  * the VGA registers to control things like backlights etc. Hopefully newer
970  * multi-GPU laptops do something saner, and desktops won't have any
971  * special ACPI for this. The driver will get a callback when VGA
979  * Returns: 0 on success, -ENODEV on failure
990 		vgadev->set_decode = set_decode;  in vga_client_register()
993 		return -ENODEV;  in vga_client_register()
1004  *                attached to the default VGA device of the system.
1015  *                card_ID and an -ENODEV error is returned for any command
1024  *   trylock <io_state> : non-blocking acquire locks on target
1046  * If the device is hot-unplugged, there is a hook inside the module to notify
1052 #define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)
1073  * Take a string in the format: "PCI:domain:bus:dev.fn" and return the
1074  * respective values. If the string is not in this format, return 0.
1094 	struct vga_arb_private *priv = file->private_data;  in vga_arb_read()
1104 		return -ENOMEM;  in vga_arb_read()
1110 	pdev = priv->target;  in vga_arb_read()
1133 		       vga_iostate_to_str(vgadev->decodes),  in vga_arb_read()
1134 		       vga_iostate_to_str(vgadev->owns),  in vga_arb_read()
1135 		       vga_iostate_to_str(vgadev->locks),  in vga_arb_read()
1136 		       vgadev->io_lock_cnt, vgadev->mem_lock_cnt);  in vga_arb_read()
1147 		return -EFAULT;  in vga_arb_read()
1158 	struct vga_arb_private *priv = file->private_data;  in vga_arb_write()
1171 		return -EINVAL;  in vga_arb_write()
1173 		return -EFAULT;  in vga_arb_write()
1179 		remaining -= 5;  in vga_arb_write()
1184 			ret_val = -EPROTO;  in vga_arb_write()
1188 			ret_val = -EPROTO;  in vga_arb_write()
1192 		pdev = priv->target;  in vga_arb_write()
1193 		if (priv->target == NULL) {  in vga_arb_write()
1194 			ret_val = -ENODEV;  in vga_arb_write()
1202 			if (priv->cards[i].pdev == pdev) {  in vga_arb_write()
1204 					priv->cards[i].io_cnt++;  in vga_arb_write()
1206 					priv->cards[i].mem_cnt++;  in vga_arb_write()
1215 		remaining -= 7;  in vga_arb_write()
1224 				ret_val = -EPROTO;  in vga_arb_write()
1229 			   ret_val = -EPROTO;  in vga_arb_write()
1235 		pdev = priv->target;  in vga_arb_write()
1236 		if (priv->target == NULL) {  in vga_arb_write()
1237 			ret_val = -ENODEV;  in vga_arb_write()
1241 			if (priv->cards[i].pdev == pdev)  in vga_arb_write()
1242 				uc = &priv->cards[i];  in vga_arb_write()
1246 			ret_val = -EINVAL;  in vga_arb_write()
1250 		if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {  in vga_arb_write()
1251 			ret_val = -EINVAL;  in vga_arb_write()
1255 		if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {  in vga_arb_write()
1256 			ret_val = -EINVAL;  in vga_arb_write()
1263 			uc->io_cnt--;  in vga_arb_write()
1265 			uc->mem_cnt--;  in vga_arb_write()
1271 		remaining -= 8;  in vga_arb_write()
1276 			ret_val = -EPROTO;  in vga_arb_write()
1281 		   ret_val = -EPROTO;  in vga_arb_write()
1286 		pdev = priv->target;  in vga_arb_write()
1287 		if (priv->target == NULL) {  in vga_arb_write()
1288 			ret_val = -ENODEV;  in vga_arb_write()
1295 				if (priv->cards[i].pdev == pdev) {  in vga_arb_write()
1297 						priv->cards[i].io_cnt++;  in vga_arb_write()
1299 						priv->cards[i].mem_cnt++;  in vga_arb_write()
1306 			ret_val = -EBUSY;  in vga_arb_write()
1315 		remaining -= 7;  in vga_arb_write()
1323 				ret_val = -EPROTO;  in vga_arb_write()
1331 				ret_val = -ENODEV;  in vga_arb_write()
1344 				vgaarb_dbg(&pdev->dev, "not a VGA device\n");  in vga_arb_write()
1348 			ret_val = -ENODEV;  in vga_arb_write()
1352 		priv->target = pdev;  in vga_arb_write()
1354 			if (priv->cards[i].pdev == pdev)  in vga_arb_write()
1356 			if (priv->cards[i].pdev == NULL) {  in vga_arb_write()
1357 				priv->cards[i].pdev = pdev;  in vga_arb_write()
1358 				priv->cards[i].io_cnt = 0;  in vga_arb_write()
1359 				priv->cards[i].mem_cnt = 0;  in vga_arb_write()
1364 			vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",  in vga_arb_write()
1368 			ret_val =  -ENOMEM;  in vga_arb_write()
1379 		remaining -= 8;  in vga_arb_write()
1383 			ret_val = -EPROTO;  in vga_arb_write()
1386 		pdev = priv->target;  in vga_arb_write()
1387 		if (priv->target == NULL) {  in vga_arb_write()
1388 			ret_val = -ENODEV;  in vga_arb_write()
1397 	return -EPROTO;  in vga_arb_write()
1420 		return -ENOMEM;  in vga_arb_open()
1421 	spin_lock_init(&priv->lock);  in vga_arb_open()
1422 	file->private_data = priv;  in vga_arb_open()
1425 	list_add(&priv->list, &vga_user_list);  in vga_arb_open()
1429 	priv->target = vga_default_device(); /* Maybe this is still null! */  in vga_arb_open()
1430 	priv->cards[0].pdev = priv->target;  in vga_arb_open()
1431 	priv->cards[0].io_cnt = 0;  in vga_arb_open()
1432 	priv->cards[0].mem_cnt = 0;  in vga_arb_open()
1439 	struct vga_arb_private *priv = file->private_data;  in vga_arb_release()
1447 	list_del(&priv->list);  in vga_arb_release()
1449 		uc = &priv->cards[i];  in vga_arb_release()
1450 		if (uc->pdev == NULL)  in vga_arb_release()
1452 		vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",  in vga_arb_release()
1453 			uc->io_cnt, uc->mem_cnt);  in vga_arb_release()
1454 		while (uc->io_cnt--)  in vga_arb_release()
1455 			vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);  in vga_arb_release()
1456 		while (uc->mem_cnt--)  in vga_arb_release()
1457 			vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);  in vga_arb_release()
1467  * Callback any registered clients to let them know we have a change in VGA
1484 		if (vgadev->set_decode) {  in vga_arbiter_notify_clients()
1485 			new_decodes = vgadev->set_decode(vgadev->pdev,  in vga_arbiter_notify_clients()
1502 	/* Only deal with VGA class devices */  in pci_notify()
1509 	 * for the cases of hot-pluggable VGA cards.  in pci_notify()
1549 	/* Add all VGA class PCI devices by default */  in vga_arb_device_init()