root/drivers/gpu/vga/vga_switcheroo.c

DEFINITIONS

1. vga_switcheroo_ready
2. vga_switcheroo_enable
3. vga_switcheroo_register_handler
4. vga_switcheroo_unregister_handler
5. register_client
6. vga_switcheroo_register_client
7. vga_switcheroo_register_audio_client
8. find_client_from_pci
9. find_client_from_id
10. find_active_client
11. vga_switcheroo_client_probe_defer
12. vga_switcheroo_pwr_state
13. vga_switcheroo_get_client_state
14. vga_switcheroo_unregister_client
15. vga_switcheroo_client_fb_set
16. vga_switcheroo_lock_ddc
17. vga_switcheroo_unlock_ddc
18. vga_switcheroo_show
19. vga_switcheroo_debugfs_open
20. vga_switchon
21. vga_switchoff
22. set_audio_state
23. vga_switchto_stage1
24. vga_switchto_stage2
25. check_can_switch
26. vga_switcheroo_debugfs_write
27. vga_switcheroo_debugfs_fini
28. vga_switcheroo_debugfs_init
29. vga_switcheroo_process_delayed_switch
30. vga_switcheroo_power_switch
31. vga_switcheroo_runtime_suspend
32. vga_switcheroo_runtime_resume
33. vga_switcheroo_init_domain_pm_ops
34. vga_switcheroo_fini_domain_pm_ops

   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  */
 113 struct 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  */
 128 static 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  */
 149 struct 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 
 170 static void vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
 171 static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);
 172 
 173 /* only one switcheroo per system */
 174 static 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 
 179 static 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 
 186 static 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  */
 235 int 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 }
 254 EXPORT_SYMBOL(vga_switcheroo_register_handler);
 255 
 256 /**
 257  * vga_switcheroo_unregister_handler() - unregister handler
 258  *
 259  * Unregister handler. Disable vga_switcheroo.
 260  */
 261 void 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 }
 275 EXPORT_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  */
 285 enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void)
 286 {
 287         return vgasr_priv.handler_flags;
 288 }
 289 EXPORT_SYMBOL(vga_switcheroo_handler_flags);
 290 
 291 static 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  */
 339 int 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 }
 347 EXPORT_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  */
 362 int 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 }
 391 EXPORT_SYMBOL(vga_switcheroo_register_audio_client);
 392 
 393 static struct vga_switcheroo_client *
 394 find_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 
 404 static struct vga_switcheroo_client *
 405 find_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 
 416 static struct vga_switcheroo_client *
 417 find_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  */
 438 bool 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 }
 452 EXPORT_SYMBOL(vga_switcheroo_client_probe_defer);
 453 
 454 static enum vga_switcheroo_state
 455 vga_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  */
 476 enum 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 }
 490 EXPORT_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  */
 498 void 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 }
 517 EXPORT_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  */
 527 void 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 }
 538 EXPORT_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  */
 559 int 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 }
 573 EXPORT_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  */
 591 int 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 }
 608 EXPORT_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 
 646 static 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 
 667 static int vga_switcheroo_debugfs_open(struct inode *inode, struct file *file)
 668 {
 669         return single_open(file, vga_switcheroo_show, NULL);
 670 }
 671 
 672 static 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 
 684 static 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 
 696 static 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 */
 707 static 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 */
 723 static 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 
 761 static 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 
 774 static ssize_t
 775 vga_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 
 894 out:
 895         mutex_unlock(&vgasr_mutex);
 896         return cnt;
 897 }
 898 
 899 static 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 
 908 static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv)
 909 {
 910         debugfs_remove_recursive(priv->debugfs_root);
 911         priv->debugfs_root = NULL;
 912 }
 913 
 914 static 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. DRM drivers should call this
 930  * from their ->lastclose callback.
 931  *
 932  * Return: 0 on success. -EINVAL if no delayed switch is pending, if the client
 933  * has unregistered in the meantime or if there are other clients blocking the
 934  * switch. If the actual switch fails, an error is reported and 0 is returned.
 935  */
 936 int vga_switcheroo_process_delayed_switch(void)
 937 {
 938         struct vga_switcheroo_client *client;
 939         int ret;
 940         int err = -EINVAL;
 941 
 942         mutex_lock(&vgasr_mutex);
 943         if (!vgasr_priv.delayed_switch_active)
 944                 goto err;
 945 
 946         pr_info("processing delayed switch to %d\n",
 947                 vgasr_priv.delayed_client_id);
 948 
 949         client = find_client_from_id(&vgasr_priv.clients,
 950                                      vgasr_priv.delayed_client_id);
 951         if (!client || !check_can_switch())
 952                 goto err;
 953 
 954         ret = vga_switchto_stage2(client);
 955         if (ret)
 956                 pr_err("delayed switching failed stage 2 %d\n", ret);
 957 
 958         vgasr_priv.delayed_switch_active = false;
 959         err = 0;
 960 err:
 961         mutex_unlock(&vgasr_mutex);
 962         return err;
 963 }
 964 EXPORT_SYMBOL(vga_switcheroo_process_delayed_switch);
 965 
 966 /**
 967  * DOC: Driver power control
 968  *
 969  * In this mode of use, the discrete GPU automatically powers up and down at
 970  * the discretion of the driver's runtime pm. On muxed machines, the user may
 971  * still influence the muxer state by way of the debugfs interface, however
 972  * the ON and OFF commands become a no-op for the discrete GPU.
 973  *
 974  * This mode is the default on Nvidia HybridPower/Optimus and ATI PowerXpress.
 975  * Specifying nouveau.runpm=0, radeon.runpm=0 or amdgpu.runpm=0 on the kernel
 976  * command line disables it.
 977  *
 978  * After the GPU has been suspended, the handler needs to be called to cut
 979  * power to the GPU. Likewise it needs to reinstate power before the GPU
 980  * can resume. This is achieved by vga_switcheroo_init_domain_pm_ops(),
 981  * which augments the GPU's suspend/resume functions by the requisite
 982  * calls to the handler.
 983  *
 984  * When the audio device resumes, the GPU needs to be woken. This is achieved
 985  * by a PCI quirk which calls device_link_add() to declare a dependency on the
 986  * GPU. That way, the GPU is kept awake whenever and as long as the audio
 987  * device is in use.
 988  *
 989  * On muxed machines, if the mux is initially switched to the discrete GPU,
 990  * the user ends up with a black screen when the GPU powers down after boot.
 991  * As a workaround, the mux is forced to the integrated GPU on runtime suspend,
 992  * cf. https://bugs.freedesktop.org/show_bug.cgi?id=75917
 993  */
 994 
 995 static void vga_switcheroo_power_switch(struct pci_dev *pdev,
 996                                         enum vga_switcheroo_state state)
 997 {
 998         struct vga_switcheroo_client *client;
 999 
1000         if (!vgasr_priv.handler->power_state)
1001                 return;
1002 
1003         client = find_client_from_pci(&vgasr_priv.clients, pdev);
1004         if (!client)
1005                 return;
1006 
1007         if (!client->driver_power_control)
1008                 return;
1009 
1010         vgasr_priv.handler->power_state(client->id, state);
1011 }
1012 
1013 /* switcheroo power domain */
1014 static int vga_switcheroo_runtime_suspend(struct device *dev)
1015 {
1016         struct pci_dev *pdev = to_pci_dev(dev);
1017         int ret;
1018 
1019         ret = dev->bus->pm->runtime_suspend(dev);
1020         if (ret)
1021                 return ret;
1022         mutex_lock(&vgasr_mutex);
1023         if (vgasr_priv.handler->switchto) {
1024                 mutex_lock(&vgasr_priv.mux_hw_lock);
1025                 vgasr_priv.handler->switchto(VGA_SWITCHEROO_IGD);
1026                 mutex_unlock(&vgasr_priv.mux_hw_lock);
1027         }
1028         pci_bus_set_current_state(pdev->bus, PCI_D3cold);
1029         vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_OFF);
1030         mutex_unlock(&vgasr_mutex);
1031         return 0;
1032 }
1033 
1034 static int vga_switcheroo_runtime_resume(struct device *dev)
1035 {
1036         struct pci_dev *pdev = to_pci_dev(dev);
1037         int ret;
1038 
1039         mutex_lock(&vgasr_mutex);
1040         vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_ON);
1041         mutex_unlock(&vgasr_mutex);
1042         pci_wakeup_bus(pdev->bus);
1043         ret = dev->bus->pm->runtime_resume(dev);
1044         if (ret)
1045                 return ret;
1046 
1047         return 0;
1048 }
1049 
1050 /**
1051  * vga_switcheroo_init_domain_pm_ops() - helper for driver power control
1052  * @dev: vga client device
1053  * @domain: power domain
1054  *
1055  * Helper for GPUs whose power state is controlled by the driver's runtime pm.
1056  * After the GPU has been suspended, the handler needs to be called to cut
1057  * power to the GPU. Likewise it needs to reinstate power before the GPU
1058  * can resume. To this end, this helper augments the suspend/resume functions
1059  * by the requisite calls to the handler. It needs only be called on platforms
1060  * where the power switch is separate to the device being powered down.
1061  */
1062 int vga_switcheroo_init_domain_pm_ops(struct device *dev,
1063                                       struct dev_pm_domain *domain)
1064 {
1065         /* copy over all the bus versions */
1066         if (dev->bus && dev->bus->pm) {
1067                 domain->ops = *dev->bus->pm;
1068                 domain->ops.runtime_suspend = vga_switcheroo_runtime_suspend;
1069                 domain->ops.runtime_resume = vga_switcheroo_runtime_resume;
1070 
1071                 dev_pm_domain_set(dev, domain);
1072                 return 0;
1073         }
1074         dev_pm_domain_set(dev, NULL);
1075         return -EINVAL;
1076 }
1077 EXPORT_SYMBOL(vga_switcheroo_init_domain_pm_ops);
1078 
1079 void vga_switcheroo_fini_domain_pm_ops(struct device *dev)
1080 {
1081         dev_pm_domain_set(dev, NULL);
1082 }
1083 EXPORT_SYMBOL(vga_switcheroo_fini_domain_pm_ops);