1/*
   2 * vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs
   3 *
   4 * Copyright (c) 2010 Red Hat Inc.
   5 * Author : Dave Airlie <airlied@redhat.com>
   6 *
   7 * Copyright (c) 2015 Lukas Wunner <lukas@wunner.de>
   8 *
   9 * Permission is hereby granted, free of charge, to any person obtaining a
  10 * copy of this software and associated documentation files (the "Software"),
  11 * to deal in the Software without restriction, including without limitation
  12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13 * and/or sell copies of the Software, and to permit persons to whom the
  14 * Software is furnished to do so, subject to the following conditions:
  15 *
  16 * The above copyright notice and this permission notice (including the next
  17 * paragraph) shall be included in all copies or substantial portions of the
  18 * Software.
  19 *
  20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  23 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  26 * DEALINGS
  27 * IN THE SOFTWARE.
  28 *
  29 */
  30
  31#define pr_fmt(fmt) "vga_switcheroo: " fmt
  32
  33#include <linux/apple-gmux.h>
  34#include <linux/console.h>
  35#include <linux/debugfs.h>
  36#include <linux/fb.h>
  37#include <linux/fs.h>
  38#include <linux/fbcon.h>
  39#include <linux/module.h>
  40#include <linux/pci.h>
  41#include <linux/pm_domain.h>
  42#include <linux/pm_runtime.h>
  43#include <linux/seq_file.h>
  44#include <linux/uaccess.h>
  45#include <linux/vgaarb.h>
  46#include <linux/vga_switcheroo.h>
  47
  48/**
  49 * DOC: Overview
  50 *
  51 * vga_switcheroo is the Linux subsystem for laptop hybrid graphics.
  52 * These come in two flavors:
  53 *
  54 * * muxed: Dual GPUs with a multiplexer chip to switch outputs between GPUs.
  55 * * muxless: Dual GPUs but only one of them is connected to outputs.
  56 *   The other one is merely used to offload rendering, its results
  57 *   are copied over PCIe into the framebuffer. On Linux this is
  58 *   supported with DRI PRIME.
  59 *
  60 * Hybrid graphics started to appear in the late Naughties and were initially
  61 * all muxed. Newer laptops moved to a muxless architecture for cost reasons.
  62 * A notable exception is the MacBook Pro which continues to use a mux.
  63 * Muxes come with varying capabilities: Some switch only the panel, others
  64 * can also switch external displays. Some switch all display pins at once
  65 * while others can switch just the DDC lines. (To allow EDID probing
  66 * for the inactive GPU.) Also, muxes are often used to cut power to the
  67 * discrete GPU while it is not used.
  68 *
  69 * DRM drivers register GPUs with vga_switcheroo, these are henceforth called
  70 * clients. The mux is called the handler. Muxless machines also register a
  71 * handler to control the power state of the discrete GPU, its ->switchto
  72 * callback is a no-op for obvious reasons. The discrete GPU is often equipped
  73 * with an HDA controller for the HDMI/DP audio signal, this will also
  74 * register as a client so that vga_switcheroo can take care of the correct
  75 * suspend/resume order when changing the discrete GPU's power state. In total
  76 * there can thus be up to three clients: Two vga clients (GPUs) and one audio
  77 * client (on the discrete GPU). The code is mostly prepared to support
  78 * machines with more than two GPUs should they become available.
  79 *
  80 * The GPU to which the outputs are currently switched is called the
  81 * active client in vga_switcheroo parlance. The GPU not in use is the
  82 * inactive client. When the inactive client's DRM driver is loaded,
  83 * it will be unable to probe the panel's EDID and hence depends on
  84 * VBIOS to provide its display modes. If the VBIOS modes are bogus or
  85 * if there is no VBIOS at all (which is common on the MacBook Pro),
  86 * a client may alternatively request that the DDC lines are temporarily
  87 * switched to it, provided that the handler supports this. Switching
  88 * only the DDC lines and not the entire output avoids unnecessary
  89 * flickering.
  90 */
  91
  92/**
  93 * struct vga_switcheroo_client - registered client
  94 * @pdev: client pci device
  95 * @fb_info: framebuffer to which console is remapped on switching
  96 * @pwr_state: current power state if manual power control is used.
  97 *	For driver power control, call vga_switcheroo_pwr_state().
  98 * @ops: client callbacks
  99 * @id: client identifier. Determining the id requires the handler,
 100 *	so gpus are initially assigned VGA_SWITCHEROO_UNKNOWN_ID
 101 *	and later given their true id in vga_switcheroo_enable()
 102 * @active: whether the outputs are currently switched to this client
 103 * @driver_power_control: whether power state is controlled by the driver's
 104 *	runtime pm. If true, writing ON and OFF to the vga_switcheroo debugfs
 105 *	interface is a no-op so as not to interfere with runtime pm
 106 * @list: client list
 107 * @vga_dev: pci device, indicate which GPU is bound to current audio client
 108 *
 109 * Registered client. A client can be either a GPU or an audio device on a GPU.
 110 * For audio clients, the @fb_info and @active members are bogus. For GPU
 111 * clients, the @vga_dev is bogus.
 112 */
 113struct vga_switcheroo_client {
 114	struct pci_dev *pdev;
 115	struct fb_info *fb_info;
 116	enum vga_switcheroo_state pwr_state;
 117	const struct vga_switcheroo_client_ops *ops;
 118	enum vga_switcheroo_client_id id;
 119	bool active;
 120	bool driver_power_control;
 121	struct list_head list;
 122	struct pci_dev *vga_dev;
 123};
 124
 125/*
 126 * protects access to struct vgasr_priv
 127 */
 128static DEFINE_MUTEX(vgasr_mutex);
 129
 130/**
 131 * struct vgasr_priv - vga_switcheroo private data
 132 * @active: whether vga_switcheroo is enabled.
 133 *	Prerequisite is the registration of two GPUs and a handler
 134 * @delayed_switch_active: whether a delayed switch is pending
 135 * @delayed_client_id: client to which a delayed switch is pending
 136 * @debugfs_root: directory for vga_switcheroo debugfs interface
 137 * @registered_clients: number of registered GPUs
 138 *	(counting only vga clients, not audio clients)
 139 * @clients: list of registered clients
 140 * @handler: registered handler
 141 * @handler_flags: flags of registered handler
 142 * @mux_hw_lock: protects mux state
 143 *	(in particular while DDC lines are temporarily switched)
 144 * @old_ddc_owner: client to which DDC lines will be switched back on unlock
 145 *
 146 * vga_switcheroo private data. Currently only one vga_switcheroo instance
 147 * per system is supported.
 148 */
 149struct vgasr_priv {
 150	bool active;
 151	bool delayed_switch_active;
 152	enum vga_switcheroo_client_id delayed_client_id;
 153
 154	struct dentry *debugfs_root;
 155
 156	int registered_clients;
 157	struct list_head clients;
 158
 159	const struct vga_switcheroo_handler *handler;
 160	enum vga_switcheroo_handler_flags_t handler_flags;
 161	struct mutex mux_hw_lock;
 162	int old_ddc_owner;
 163};
 164
 165#define ID_BIT_AUDIO		0x100
 166#define client_is_audio(c)		((c)->id & ID_BIT_AUDIO)
 167#define client_is_vga(c)		(!client_is_audio(c))
 168#define client_id(c)		((c)->id & ~ID_BIT_AUDIO)
 169
 170static void vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
 171static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);
 172
 173/* only one switcheroo per system */
 174static struct vgasr_priv vgasr_priv = {
 175	.clients = LIST_HEAD_INIT(vgasr_priv.clients),
 176	.mux_hw_lock = __MUTEX_INITIALIZER(vgasr_priv.mux_hw_lock),
 177};
 178
 179static bool vga_switcheroo_ready(void)
 180{
 181	/* we're ready if we get two clients + handler */
 182	return !vgasr_priv.active &&
 183	       vgasr_priv.registered_clients == 2 && vgasr_priv.handler;
 184}
 185
 186static void vga_switcheroo_enable(void)
 187{
 188	int ret;
 189	struct vga_switcheroo_client *client;
 190
 191	/* call the handler to init */
 192	if (vgasr_priv.handler->init)
 193		vgasr_priv.handler->init();
 194
 195	list_for_each_entry(client, &vgasr_priv.clients, list) {
 196		if (!client_is_vga(client) ||
 197		     client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
 198			continue;
 199
 200		ret = vgasr_priv.handler->get_client_id(client->pdev);
 201		if (ret < 0)
 202			return;
 203
 204		client->id = ret;
 205	}
 206
 207	list_for_each_entry(client, &vgasr_priv.clients, list) {
 208		if (!client_is_audio(client) ||
 209		     client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
 210			continue;
 211
 212		ret = vgasr_priv.handler->get_client_id(client->vga_dev);
 213		if (ret < 0)
 214			return;
 215
 216		client->id = ret | ID_BIT_AUDIO;
 217		if (client->ops->gpu_bound)
 218			client->ops->gpu_bound(client->pdev, ret);
 219	}
 220
 221	vga_switcheroo_debugfs_init(&vgasr_priv);
 222	vgasr_priv.active = true;
 223}
 224
 225/**
 226 * vga_switcheroo_register_handler() - register handler
 227 * @handler: handler callbacks
 228 * @handler_flags: handler flags
 229 *
 230 * Register handler. Enable vga_switcheroo if two vga clients have already
 231 * registered.
 232 *
 233 * Return: 0 on success, -EINVAL if a handler was already registered.
 234 */
 235int vga_switcheroo_register_handler(
 236			  const struct vga_switcheroo_handler *handler,
 237			  enum vga_switcheroo_handler_flags_t handler_flags)
 238{
 239	mutex_lock(&vgasr_mutex);
 240	if (vgasr_priv.handler) {
 241		mutex_unlock(&vgasr_mutex);
 242		return -EINVAL;
 243	}
 244
 245	vgasr_priv.handler = handler;
 246	vgasr_priv.handler_flags = handler_flags;
 247	if (vga_switcheroo_ready()) {
 248		pr_info("enabled\n");
 249		vga_switcheroo_enable();
 250	}
 251	mutex_unlock(&vgasr_mutex);
 252	return 0;
 253}
 254EXPORT_SYMBOL(vga_switcheroo_register_handler);
 255
 256/**
 257 * vga_switcheroo_unregister_handler() - unregister handler
 258 *
 259 * Unregister handler. Disable vga_switcheroo.
 260 */
 261void vga_switcheroo_unregister_handler(void)
 262{
 263	mutex_lock(&vgasr_mutex);
 264	mutex_lock(&vgasr_priv.mux_hw_lock);
 265	vgasr_priv.handler_flags = 0;
 266	vgasr_priv.handler = NULL;
 267	if (vgasr_priv.active) {
 268		pr_info("disabled\n");
 269		vga_switcheroo_debugfs_fini(&vgasr_priv);
 270		vgasr_priv.active = false;
 271	}
 272	mutex_unlock(&vgasr_priv.mux_hw_lock);
 273	mutex_unlock(&vgasr_mutex);
 274}
 275EXPORT_SYMBOL(vga_switcheroo_unregister_handler);
 276
 277/**
 278 * vga_switcheroo_handler_flags() - obtain handler flags
 279 *
 280 * Helper for clients to obtain the handler flags bitmask.
 281 *
 282 * Return: Handler flags. A value of 0 means that no handler is registered
 283 * or that the handler has no special capabilities.
 284 */
 285enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void)
 286{
 287	return vgasr_priv.handler_flags;
 288}
 289EXPORT_SYMBOL(vga_switcheroo_handler_flags);
 290
 291static int register_client(struct pci_dev *pdev,
 292			   const struct vga_switcheroo_client_ops *ops,
 293			   enum vga_switcheroo_client_id id,
 294			   struct pci_dev *vga_dev,
 295			   bool active,
 296			   bool driver_power_control)
 297{
 298	struct vga_switcheroo_client *client;
 299
 300	client = kzalloc(sizeof(*client), GFP_KERNEL);
 301	if (!client)
 302		return -ENOMEM;
 303
 304	client->pwr_state = VGA_SWITCHEROO_ON;
 305	client->pdev = pdev;
 306	client->ops = ops;
 307	client->id = id;
 308	client->active = active;
 309	client->driver_power_control = driver_power_control;
 310	client->vga_dev = vga_dev;
 311
 312	mutex_lock(&vgasr_mutex);
 313	list_add_tail(&client->list, &vgasr_priv.clients);
 314	if (client_is_vga(client))
 315		vgasr_priv.registered_clients++;
 316
 317	if (vga_switcheroo_ready()) {
 318		pr_info("enabled\n");
 319		vga_switcheroo_enable();
 320	}
 321	mutex_unlock(&vgasr_mutex);
 322	return 0;
 323}
 324
 325/**
 326 * vga_switcheroo_register_client - register vga client
 327 * @pdev: client pci device
 328 * @ops: client callbacks
 329 * @driver_power_control: whether power state is controlled by the driver's
 330 *	runtime pm
 331 *
 332 * Register vga client (GPU). Enable vga_switcheroo if another GPU and a
 333 * handler have already registered. The power state of the client is assumed
 334 * to be ON. Beforehand, vga_switcheroo_client_probe_defer() shall be called
 335 * to ensure that all prerequisites are met.
 336 *
 337 * Return: 0 on success, -ENOMEM on memory allocation error.
 338 */
 339int vga_switcheroo_register_client(struct pci_dev *pdev,
 340				   const struct vga_switcheroo_client_ops *ops,
 341				   bool driver_power_control)
 342{
 343	return register_client(pdev, ops, VGA_SWITCHEROO_UNKNOWN_ID, NULL,
 344			       pdev == vga_default_device(),
 345			       driver_power_control);
 346}
 347EXPORT_SYMBOL(vga_switcheroo_register_client);
 348
 349/**
 350 * vga_switcheroo_register_audio_client - register audio client
 351 * @pdev: client pci device
 352 * @ops: client callbacks
 353 * @vga_dev:  pci device which is bound to current audio client
 354 *
 355 * Register audio client (audio device on a GPU). The client is assumed
 356 * to use runtime PM. Beforehand, vga_switcheroo_client_probe_defer()
 357 * shall be called to ensure that all prerequisites are met.
 358 *
 359 * Return: 0 on success, -ENOMEM on memory allocation error, -EINVAL on getting
 360 * client id error.
 361 */
 362int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
 363			const struct vga_switcheroo_client_ops *ops,
 364			struct pci_dev *vga_dev)
 365{
 366	enum vga_switcheroo_client_id id = VGA_SWITCHEROO_UNKNOWN_ID;
 367
 368	/*
 369	 * if vga_switcheroo has enabled, that mean two GPU clients and also
 370	 * handler are registered. Get audio client id from bound GPU client
 371	 * id directly, otherwise, set it as VGA_SWITCHEROO_UNKNOWN_ID,
 372	 * it will set to correct id in later when vga_switcheroo_enable()
 373	 * is called.
 374	 */
 375	mutex_lock(&vgasr_mutex);
 376	if (vgasr_priv.active) {
 377		id = vgasr_priv.handler->get_client_id(vga_dev);
 378		if (id < 0) {
 379			mutex_unlock(&vgasr_mutex);
 380			return -EINVAL;
 381		}
 382		/* notify if GPU has been already bound */
 383		if (ops->gpu_bound)
 384			ops->gpu_bound(pdev, id);
 385	}
 386	mutex_unlock(&vgasr_mutex);
 387
 388	return register_client(pdev, ops, id | ID_BIT_AUDIO, vga_dev,
 389			       false, true);
 390}
 391EXPORT_SYMBOL(vga_switcheroo_register_audio_client);
 392
 393static struct vga_switcheroo_client *
 394find_client_from_pci(struct list_head *head, struct pci_dev *pdev)
 395{
 396	struct vga_switcheroo_client *client;
 397
 398	list_for_each_entry(client, head, list)
 399		if (client->pdev == pdev)
 400			return client;
 401	return NULL;
 402}
 403
 404static struct vga_switcheroo_client *
 405find_client_from_id(struct list_head *head,
 406		    enum vga_switcheroo_client_id client_id)
 407{
 408	struct vga_switcheroo_client *client;
 409
 410	list_for_each_entry(client, head, list)
 411		if (client->id == client_id)
 412			return client;
 413	return NULL;
 414}
 415
 416static struct vga_switcheroo_client *
 417find_active_client(struct list_head *head)
 418{
 419	struct vga_switcheroo_client *client;
 420
 421	list_for_each_entry(client, head, list)
 422		if (client->active)
 423			return client;
 424	return NULL;
 425}
 426
 427/**
 428 * vga_switcheroo_client_probe_defer() - whether to defer probing a given client
 429 * @pdev: client pci device
 430 *
 431 * Determine whether any prerequisites are not fulfilled to probe a given
 432 * client. Drivers shall invoke this early on in their ->probe callback
 433 * and return %-EPROBE_DEFER if it evaluates to %true. Thou shalt not
 434 * register the client ere thou hast called this.
 435 *
 436 * Return: %true if probing should be deferred, otherwise %false.
 437 */
 438bool vga_switcheroo_client_probe_defer(struct pci_dev *pdev)
 439{
 440	if ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY) {
 441		/*
 442		 * apple-gmux is needed on pre-retina MacBook Pro
 443		 * to probe the panel if pdev is the inactive GPU.
 444		 */
 445		if (apple_gmux_present() && pdev != vga_default_device() &&
 446		    !vgasr_priv.handler_flags)
 447			return true;
 448	}
 449
 450	return false;
 451}
 452EXPORT_SYMBOL(vga_switcheroo_client_probe_defer);
 453
 454static enum vga_switcheroo_state
 455vga_switcheroo_pwr_state(struct vga_switcheroo_client *client)
 456{
 457	if (client->driver_power_control)
 458		if (pm_runtime_enabled(&client->pdev->dev) &&
 459		    pm_runtime_active(&client->pdev->dev))
 460			return VGA_SWITCHEROO_ON;
 461		else
 462			return VGA_SWITCHEROO_OFF;
 463	else
 464		return client->pwr_state;
 465}
 466
 467/**
 468 * vga_switcheroo_get_client_state() - obtain power state of a given client
 469 * @pdev: client pci device
 470 *
 471 * Obtain power state of a given client as seen from vga_switcheroo.
 472 * The function is only called from hda_intel.c.
 473 *
 474 * Return: Power state.
 475 */
 476enum vga_switcheroo_state vga_switcheroo_get_client_state(struct pci_dev *pdev)
 477{
 478	struct vga_switcheroo_client *client;
 479	enum vga_switcheroo_state ret;
 480
 481	mutex_lock(&vgasr_mutex);
 482	client = find_client_from_pci(&vgasr_priv.clients, pdev);
 483	if (!client)
 484		ret = VGA_SWITCHEROO_NOT_FOUND;
 485	else
 486		ret = vga_switcheroo_pwr_state(client);
 487	mutex_unlock(&vgasr_mutex);
 488	return ret;
 489}
 490EXPORT_SYMBOL(vga_switcheroo_get_client_state);
 491
 492/**
 493 * vga_switcheroo_unregister_client() - unregister client
 494 * @pdev: client pci device
 495 *
 496 * Unregister client. Disable vga_switcheroo if this is a vga client (GPU).
 497 */
 498void vga_switcheroo_unregister_client(struct pci_dev *pdev)
 499{
 500	struct vga_switcheroo_client *client;
 501
 502	mutex_lock(&vgasr_mutex);
 503	client = find_client_from_pci(&vgasr_priv.clients, pdev);
 504	if (client) {
 505		if (client_is_vga(client))
 506			vgasr_priv.registered_clients--;
 507		list_del(&client->list);
 508		kfree(client);
 509	}
 510	if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
 511		pr_info("disabled\n");
 512		vga_switcheroo_debugfs_fini(&vgasr_priv);
 513		vgasr_priv.active = false;
 514	}
 515	mutex_unlock(&vgasr_mutex);
 516}
 517EXPORT_SYMBOL(vga_switcheroo_unregister_client);
 518
 519/**
 520 * vga_switcheroo_client_fb_set() - set framebuffer of a given client
 521 * @pdev: client pci device
 522 * @info: framebuffer
 523 *
 524 * Set framebuffer of a given client. The console will be remapped to this
 525 * on switching.
 526 */
 527void vga_switcheroo_client_fb_set(struct pci_dev *pdev,
 528				 struct fb_info *info)
 529{
 530	struct vga_switcheroo_client *client;
 531
 532	mutex_lock(&vgasr_mutex);
 533	client = find_client_from_pci(&vgasr_priv.clients, pdev);
 534	if (client)
 535		client->fb_info = info;
 536	mutex_unlock(&vgasr_mutex);
 537}
 538EXPORT_SYMBOL(vga_switcheroo_client_fb_set);
 539
 540/**
 541 * vga_switcheroo_lock_ddc() - temporarily switch DDC lines to a given client
 542 * @pdev: client pci device
 543 *
 544 * Temporarily switch DDC lines to the client identified by @pdev
 545 * (but leave the outputs otherwise switched to where they are).
 546 * This allows the inactive client to probe EDID. The DDC lines must
 547 * afterwards be switched back by calling vga_switcheroo_unlock_ddc(),
 548 * even if this function returns an error.
 549 *
 550 * Return: Previous DDC owner on success or a negative int on error.
 551 * Specifically, %-ENODEV if no handler has registered or if the handler
 552 * does not support switching the DDC lines. Also, a negative value
 553 * returned by the handler is propagated back to the caller.
 554 * The return value has merely an informational purpose for any caller
 555 * which might be interested in it. It is acceptable to ignore the return
 556 * value and simply rely on the result of the subsequent EDID probe,
 557 * which will be %NULL if DDC switching failed.
 558 */
 559int vga_switcheroo_lock_ddc(struct pci_dev *pdev)
 560{
 561	enum vga_switcheroo_client_id id;
 562
 563	mutex_lock(&vgasr_priv.mux_hw_lock);
 564	if (!vgasr_priv.handler || !vgasr_priv.handler->switch_ddc) {
 565		vgasr_priv.old_ddc_owner = -ENODEV;
 566		return -ENODEV;
 567	}
 568
 569	id = vgasr_priv.handler->get_client_id(pdev);
 570	vgasr_priv.old_ddc_owner = vgasr_priv.handler->switch_ddc(id);
 571	return vgasr_priv.old_ddc_owner;
 572}
 573EXPORT_SYMBOL(vga_switcheroo_lock_ddc);
 574
 575/**
 576 * vga_switcheroo_unlock_ddc() - switch DDC lines back to previous owner
 577 * @pdev: client pci device
 578 *
 579 * Switch DDC lines back to the previous owner after calling
 580 * vga_switcheroo_lock_ddc(). This must be called even if
 581 * vga_switcheroo_lock_ddc() returned an error.
 582 *
 583 * Return: Previous DDC owner on success (i.e. the client identifier of @pdev)
 584 * or a negative int on error.
 585 * Specifically, %-ENODEV if no handler has registered or if the handler
 586 * does not support switching the DDC lines. Also, a negative value
 587 * returned by the handler is propagated back to the caller.
 588 * Finally, invoking this function without calling vga_switcheroo_lock_ddc()
 589 * first is not allowed and will result in %-EINVAL.
 590 */
 591int vga_switcheroo_unlock_ddc(struct pci_dev *pdev)
 592{
 593	enum vga_switcheroo_client_id id;
 594	int ret = vgasr_priv.old_ddc_owner;
 595
 596	if (WARN_ON_ONCE(!mutex_is_locked(&vgasr_priv.mux_hw_lock)))
 597		return -EINVAL;
 598
 599	if (vgasr_priv.old_ddc_owner >= 0) {
 600		id = vgasr_priv.handler->get_client_id(pdev);
 601		if (vgasr_priv.old_ddc_owner != id)
 602			ret = vgasr_priv.handler->switch_ddc(
 603						     vgasr_priv.old_ddc_owner);
 604	}
 605	mutex_unlock(&vgasr_priv.mux_hw_lock);
 606	return ret;
 607}
 608EXPORT_SYMBOL(vga_switcheroo_unlock_ddc);
 609
 610/**
 611 * DOC: Manual switching and manual power control
 612 *
 613 * In this mode of use, the file /sys/kernel/debug/vgaswitcheroo/switch
 614 * can be read to retrieve the current vga_switcheroo state and commands
 615 * can be written to it to change the state. The file appears as soon as
 616 * two GPU drivers and one handler have registered with vga_switcheroo.
 617 * The following commands are understood:
 618 *
 619 * * OFF: Power off the device not in use.
 620 * * ON: Power on the device not in use.
 621 * * IGD: Switch to the integrated graphics device.
 622 *   Power on the integrated GPU if necessary, power off the discrete GPU.
 623 *   Prerequisite is that no user space processes (e.g. Xorg, alsactl)
 624 *   have opened device files of the GPUs or the audio client. If the
 625 *   switch fails, the user may invoke lsof(8) or fuser(1) on /dev/dri/
 626 *   and /dev/snd/controlC1 to identify processes blocking the switch.
 627 * * DIS: Switch to the discrete graphics device.
 628 * * DIGD: Delayed switch to the integrated graphics device.
 629 *   This will perform the switch once the last user space process has
 630 *   closed the device files of the GPUs and the audio client.
 631 * * DDIS: Delayed switch to the discrete graphics device.
 632 * * MIGD: Mux-only switch to the integrated graphics device.
 633 *   Does not remap console or change the power state of either gpu.
 634 *   If the integrated GPU is currently off, the screen will turn black.
 635 *   If it is on, the screen will show whatever happens to be in VRAM.
 636 *   Either way, the user has to blindly enter the command to switch back.
 637 * * MDIS: Mux-only switch to the discrete graphics device.
 638 *
 639 * For GPUs whose power state is controlled by the driver's runtime pm,
 640 * the ON and OFF commands are a no-op (see next section).
 641 *
 642 * For muxless machines, the IGD/DIS, DIGD/DDIS and MIGD/MDIS commands
 643 * should not be used.
 644 */
 645
 646static int vga_switcheroo_show(struct seq_file *m, void *v)
 647{
 648	struct vga_switcheroo_client *client;
 649	int i = 0;
 650
 651	mutex_lock(&vgasr_mutex);
 652	list_for_each_entry(client, &vgasr_priv.clients, list) {
 653		seq_printf(m, "%d:%s%s:%c:%s%s:%s\n", i,
 654			   client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" :
 655								     "IGD",
 656			   client_is_vga(client) ? "" : "-Audio",
 657			   client->active ? '+' : ' ',
 658			   client->driver_power_control ? "Dyn" : "",
 659			   vga_switcheroo_pwr_state(client) ? "Pwr" : "Off",
 660			   pci_name(client->pdev));
 661		i++;
 662	}
 663	mutex_unlock(&vgasr_mutex);
 664	return 0;
 665}
 666
 667static int vga_switcheroo_debugfs_open(struct inode *inode, struct file *file)
 668{
 669	return single_open(file, vga_switcheroo_show, NULL);
 670}
 671
 672static int vga_switchon(struct vga_switcheroo_client *client)
 673{
 674	if (client->driver_power_control)
 675		return 0;
 676	if (vgasr_priv.handler->power_state)
 677		vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_ON);
 678	/* call the driver callback to turn on device */
 679	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_ON);
 680	client->pwr_state = VGA_SWITCHEROO_ON;
 681	return 0;
 682}
 683
 684static int vga_switchoff(struct vga_switcheroo_client *client)
 685{
 686	if (client->driver_power_control)
 687		return 0;
 688	/* call the driver callback to turn off device */
 689	client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_OFF);
 690	if (vgasr_priv.handler->power_state)
 691		vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_OFF);
 692	client->pwr_state = VGA_SWITCHEROO_OFF;
 693	return 0;
 694}
 695
 696static void set_audio_state(enum vga_switcheroo_client_id id,
 697			    enum vga_switcheroo_state state)
 698{
 699	struct vga_switcheroo_client *client;
 700
 701	client = find_client_from_id(&vgasr_priv.clients, id | ID_BIT_AUDIO);
 702	if (client)
 703		client->ops->set_gpu_state(client->pdev, state);
 704}
 705
 706/* stage one happens before delay */
 707static int vga_switchto_stage1(struct vga_switcheroo_client *new_client)
 708{
 709	struct vga_switcheroo_client *active;
 710
 711	active = find_active_client(&vgasr_priv.clients);
 712	if (!active)
 713		return 0;
 714
 715	if (vga_switcheroo_pwr_state(new_client) == VGA_SWITCHEROO_OFF)
 716		vga_switchon(new_client);
 717
 718	vga_set_default_device(new_client->pdev);
 719	return 0;
 720}
 721
 722/* post delay */
 723static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
 724{
 725	int ret;
 726	struct vga_switcheroo_client *active;
 727
 728	active = find_active_client(&vgasr_priv.clients);
 729	if (!active)
 730		return 0;
 731
 732	active->active = false;
 733
 734	/* let HDA controller autosuspend if GPU uses driver power control */
 735	if (!active->driver_power_control)
 736		set_audio_state(active->id, VGA_SWITCHEROO_OFF);
 737
 738	if (new_client->fb_info)
 739		fbcon_remap_all(new_client->fb_info);
 740
 741	mutex_lock(&vgasr_priv.mux_hw_lock);
 742	ret = vgasr_priv.handler->switchto(new_client->id);
 743	mutex_unlock(&vgasr_priv.mux_hw_lock);
 744	if (ret)
 745		return ret;
 746
 747	if (new_client->ops->reprobe)
 748		new_client->ops->reprobe(new_client->pdev);
 749
 750	if (vga_switcheroo_pwr_state(active) == VGA_SWITCHEROO_ON)
 751		vga_switchoff(active);
 752
 753	/* let HDA controller autoresume if GPU uses driver power control */
 754	if (!new_client->driver_power_control)
 755		set_audio_state(new_client->id, VGA_SWITCHEROO_ON);
 756
 757	new_client->active = true;
 758	return 0;
 759}
 760
 761static bool check_can_switch(void)
 762{
 763	struct vga_switcheroo_client *client;
 764
 765	list_for_each_entry(client, &vgasr_priv.clients, list) {
 766		if (!client->ops->can_switch(client->pdev)) {
 767			pr_err("client %x refused switch\n", client->id);
 768			return false;
 769		}
 770	}
 771	return true;
 772}
 773
 774static ssize_t
 775vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf,
 776			     size_t cnt, loff_t *ppos)
 777{
 778	char usercmd[64];
 779	int ret;
 780	bool delay = false, can_switch;
 781	bool just_mux = false;
 782	enum vga_switcheroo_client_id client_id = VGA_SWITCHEROO_UNKNOWN_ID;
 783	struct vga_switcheroo_client *client = NULL;
 784
 785	if (cnt > 63)
 786		cnt = 63;
 787
 788	if (copy_from_user(usercmd, ubuf, cnt))
 789		return -EFAULT;
 790
 791	mutex_lock(&vgasr_mutex);
 792
 793	if (!vgasr_priv.active) {
 794		cnt = -EINVAL;
 795		goto out;
 796	}
 797
 798	/* pwr off the device not in use */
 799	if (strncmp(usercmd, "OFF", 3) == 0) {
 800		list_for_each_entry(client, &vgasr_priv.clients, list) {
 801			if (client->active || client_is_audio(client))
 802				continue;
 803			if (client->driver_power_control)
 804				continue;
 805			set_audio_state(client->id, VGA_SWITCHEROO_OFF);
 806			if (client->pwr_state == VGA_SWITCHEROO_ON)
 807				vga_switchoff(client);
 808		}
 809		goto out;
 810	}
 811	/* pwr on the device not in use */
 812	if (strncmp(usercmd, "ON", 2) == 0) {
 813		list_for_each_entry(client, &vgasr_priv.clients, list) {
 814			if (client->active || client_is_audio(client))
 815				continue;
 816			if (client->driver_power_control)
 817				continue;
 818			if (client->pwr_state == VGA_SWITCHEROO_OFF)
 819				vga_switchon(client);
 820			set_audio_state(client->id, VGA_SWITCHEROO_ON);
 821		}
 822		goto out;
 823	}
 824
 825	/* request a delayed switch - test can we switch now */
 826	if (strncmp(usercmd, "DIGD", 4) == 0) {
 827		client_id = VGA_SWITCHEROO_IGD;
 828		delay = true;
 829	}
 830
 831	if (strncmp(usercmd, "DDIS", 4) == 0) {
 832		client_id = VGA_SWITCHEROO_DIS;
 833		delay = true;
 834	}
 835
 836	if (strncmp(usercmd, "IGD", 3) == 0)
 837		client_id = VGA_SWITCHEROO_IGD;
 838
 839	if (strncmp(usercmd, "DIS", 3) == 0)
 840		client_id = VGA_SWITCHEROO_DIS;
 841
 842	if (strncmp(usercmd, "MIGD", 4) == 0) {
 843		just_mux = true;
 844		client_id = VGA_SWITCHEROO_IGD;
 845	}
 846	if (strncmp(usercmd, "MDIS", 4) == 0) {
 847		just_mux = true;
 848		client_id = VGA_SWITCHEROO_DIS;
 849	}
 850
 851	if (client_id == VGA_SWITCHEROO_UNKNOWN_ID)
 852		goto out;
 853	client = find_client_from_id(&vgasr_priv.clients, client_id);
 854	if (!client)
 855		goto out;
 856
 857	vgasr_priv.delayed_switch_active = false;
 858
 859	if (just_mux) {
 860		mutex_lock(&vgasr_priv.mux_hw_lock);
 861		ret = vgasr_priv.handler->switchto(client_id);
 862		mutex_unlock(&vgasr_priv.mux_hw_lock);
 863		goto out;
 864	}
 865
 866	if (client->active)
 867		goto out;
 868
 869	/* okay we want a switch - test if devices are willing to switch */
 870	can_switch = check_can_switch();
 871
 872	if (can_switch == false && delay == false)
 873		goto out;
 874
 875	if (can_switch) {
 876		ret = vga_switchto_stage1(client);
 877		if (ret)
 878			pr_err("switching failed stage 1 %d\n", ret);
 879
 880		ret = vga_switchto_stage2(client);
 881		if (ret)
 882			pr_err("switching failed stage 2 %d\n", ret);
 883
 884	} else {
 885		pr_info("setting delayed switch to client %d\n", client->id);
 886		vgasr_priv.delayed_switch_active = true;
 887		vgasr_priv.delayed_client_id = client_id;
 888
 889		ret = vga_switchto_stage1(client);
 890		if (ret)
 891			pr_err("delayed switching stage 1 failed %d\n", ret);
 892	}
 893
 894out:
 895	mutex_unlock(&vgasr_mutex);
 896	return cnt;
 897}
 898
 899static const struct file_operations vga_switcheroo_debugfs_fops = {
 900	.owner = THIS_MODULE,
 901	.open = vga_switcheroo_debugfs_open,
 902	.write = vga_switcheroo_debugfs_write,
 903	.read = seq_read,
 904	.llseek = seq_lseek,
 905	.release = single_release,
 906};
 907
 908static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv)
 909{
 910	debugfs_remove_recursive(priv->debugfs_root);
 911	priv->debugfs_root = NULL;
 912}
 913
 914static void vga_switcheroo_debugfs_init(struct vgasr_priv *priv)
 915{
 916	/* already initialised */
 917	if (priv->debugfs_root)
 918		return;
 919
 920	priv->debugfs_root = debugfs_create_dir("vgaswitcheroo", NULL);
 921
 922	debugfs_create_file("switch", 0644, priv->debugfs_root, NULL,
 923			    &vga_switcheroo_debugfs_fops);
 924}
 925
 926/**
 927 * vga_switcheroo_process_delayed_switch() - helper for delayed switching
 928 *
 929 * Process a delayed switch if one is pending.
 
 930 *
 931 * Return: 0 on success. -EINVAL if no delayed switch is pending, if the client
 932 * has unregistered in the meantime or if there are other clients blocking the
 933 * switch. If the actual switch fails, an error is reported and 0 is returned.
 934 */
 935int vga_switcheroo_process_delayed_switch(void)
 936{
 937	struct vga_switcheroo_client *client;
 938	int ret;
 939	int err = -EINVAL;
 940
 941	mutex_lock(&vgasr_mutex);
 942	if (!vgasr_priv.delayed_switch_active)
 943		goto err;
 944
 945	pr_info("processing delayed switch to %d\n",
 946		vgasr_priv.delayed_client_id);
 947
 948	client = find_client_from_id(&vgasr_priv.clients,
 949				     vgasr_priv.delayed_client_id);
 950	if (!client || !check_can_switch())
 951		goto err;
 952
 953	ret = vga_switchto_stage2(client);
 954	if (ret)
 955		pr_err("delayed switching failed stage 2 %d\n", ret);
 956
 957	vgasr_priv.delayed_switch_active = false;
 958	err = 0;
 959err:
 960	mutex_unlock(&vgasr_mutex);
 961	return err;
 962}
 963EXPORT_SYMBOL(vga_switcheroo_process_delayed_switch);
 964
 965/**
 966 * DOC: Driver power control
 967 *
 968 * In this mode of use, the discrete GPU automatically powers up and down at
 969 * the discretion of the driver's runtime pm. On muxed machines, the user may
 970 * still influence the muxer state by way of the debugfs interface, however
 971 * the ON and OFF commands become a no-op for the discrete GPU.
 972 *
 973 * This mode is the default on Nvidia HybridPower/Optimus and ATI PowerXpress.
 974 * Specifying nouveau.runpm=0, radeon.runpm=0 or amdgpu.runpm=0 on the kernel
 975 * command line disables it.
 976 *
 977 * After the GPU has been suspended, the handler needs to be called to cut
 978 * power to the GPU. Likewise it needs to reinstate power before the GPU
 979 * can resume. This is achieved by vga_switcheroo_init_domain_pm_ops(),
 980 * which augments the GPU's suspend/resume functions by the requisite
 981 * calls to the handler.
 982 *
 983 * When the audio device resumes, the GPU needs to be woken. This is achieved
 984 * by a PCI quirk which calls device_link_add() to declare a dependency on the
 985 * GPU. That way, the GPU is kept awake whenever and as long as the audio
 986 * device is in use.
 987 *
 988 * On muxed machines, if the mux is initially switched to the discrete GPU,
 989 * the user ends up with a black screen when the GPU powers down after boot.
 990 * As a workaround, the mux is forced to the integrated GPU on runtime suspend,
 991 * cf. https://bugs.freedesktop.org/show_bug.cgi?id=75917
 992 */
 993
 994static void vga_switcheroo_power_switch(struct pci_dev *pdev,
 995					enum vga_switcheroo_state state)
 996{
 997	struct vga_switcheroo_client *client;
 998
 999	if (!vgasr_priv.handler->power_state)
1000		return;
1001
1002	client = find_client_from_pci(&vgasr_priv.clients, pdev);
1003	if (!client)
1004		return;
1005
1006	if (!client->driver_power_control)
1007		return;
1008
1009	vgasr_priv.handler->power_state(client->id, state);
1010}
1011
1012/* switcheroo power domain */
1013static int vga_switcheroo_runtime_suspend(struct device *dev)
1014{
1015	struct pci_dev *pdev = to_pci_dev(dev);
1016	int ret;
1017
1018	ret = dev->bus->pm->runtime_suspend(dev);
1019	if (ret)
1020		return ret;
1021	mutex_lock(&vgasr_mutex);
1022	if (vgasr_priv.handler->switchto) {
1023		mutex_lock(&vgasr_priv.mux_hw_lock);
1024		vgasr_priv.handler->switchto(VGA_SWITCHEROO_IGD);
1025		mutex_unlock(&vgasr_priv.mux_hw_lock);
1026	}
1027	pci_bus_set_current_state(pdev->bus, PCI_D3cold);
1028	vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_OFF);
1029	mutex_unlock(&vgasr_mutex);
1030	return 0;
1031}
1032
1033static int vga_switcheroo_runtime_resume(struct device *dev)
1034{
1035	struct pci_dev *pdev = to_pci_dev(dev);
 
1036
1037	mutex_lock(&vgasr_mutex);
1038	vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_ON);
1039	mutex_unlock(&vgasr_mutex);
1040	pci_resume_bus(pdev->bus);
1041	return dev->bus->pm->runtime_resume(dev);
 
 
 
 
1042}
1043
1044/**
1045 * vga_switcheroo_init_domain_pm_ops() - helper for driver power control
1046 * @dev: vga client device
1047 * @domain: power domain
1048 *
1049 * Helper for GPUs whose power state is controlled by the driver's runtime pm.
1050 * After the GPU has been suspended, the handler needs to be called to cut
1051 * power to the GPU. Likewise it needs to reinstate power before the GPU
1052 * can resume. To this end, this helper augments the suspend/resume functions
1053 * by the requisite calls to the handler. It needs only be called on platforms
1054 * where the power switch is separate to the device being powered down.
1055 */
1056int vga_switcheroo_init_domain_pm_ops(struct device *dev,
1057				      struct dev_pm_domain *domain)
1058{
1059	/* copy over all the bus versions */
1060	if (dev->bus && dev->bus->pm) {
1061		domain->ops = *dev->bus->pm;
1062		domain->ops.runtime_suspend = vga_switcheroo_runtime_suspend;
1063		domain->ops.runtime_resume = vga_switcheroo_runtime_resume;
1064
1065		dev_pm_domain_set(dev, domain);
1066		return 0;
1067	}
1068	dev_pm_domain_set(dev, NULL);
1069	return -EINVAL;
1070}
1071EXPORT_SYMBOL(vga_switcheroo_init_domain_pm_ops);
1072
1073void vga_switcheroo_fini_domain_pm_ops(struct device *dev)
1074{
1075	dev_pm_domain_set(dev, NULL);
1076}
1077EXPORT_SYMBOL(vga_switcheroo_fini_domain_pm_ops);