drm_drv.c

   1/*
   2 * Created: Fri Jan 19 10:48:35 2001 by faith@acm.org
   3 *
   4 * Copyright 2001 VA Linux Systems, Inc., Sunnyvale, California.
   5 * All Rights Reserved.
   6 *
   7 * Author Rickard E. (Rik) Faith <faith@valinux.com>
   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 * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  24 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  25 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  26 * DEALINGS IN THE SOFTWARE.
  27 */
  28
  29#include <linux/bitops.h>
  30#include <linux/cgroup_dmem.h>
  31#include <linux/debugfs.h>
  32#include <linux/export.h>
  33#include <linux/fs.h>
  34#include <linux/module.h>
  35#include <linux/moduleparam.h>
  36#include <linux/mount.h>
  37#include <linux/pseudo_fs.h>
  38#include <linux/sched.h>
  39#include <linux/slab.h>
  40#include <linux/sprintf.h>
  41#include <linux/srcu.h>
  42#include <linux/xarray.h>
  43
  44#include <drm/drm_accel.h>
  45#include <drm/drm_bridge.h>
  46#include <drm/drm_cache.h>
  47#include <drm/drm_client_event.h>
  48#include <drm/drm_color_mgmt.h>
  49#include <drm/drm_drv.h>
  50#include <drm/drm_file.h>
  51#include <drm/drm_managed.h>
  52#include <drm/drm_mode_object.h>
  53#include <drm/drm_panic.h>
  54#include <drm/drm_print.h>
  55#include <drm/drm_privacy_screen_machine.h>
  56
  57#include "drm_crtc_internal.h"
  58#include "drm_internal.h"
  59
  60MODULE_AUTHOR("Gareth Hughes, Leif Delgass, José Fonseca, Jon Smirl");
  61MODULE_DESCRIPTION("DRM shared core routines");
  62MODULE_LICENSE("GPL and additional rights");
  63
  64DEFINE_XARRAY_ALLOC(drm_minors_xa);
  65
  66/*
  67 * If the drm core fails to init for whatever reason,
  68 * we should prevent any drivers from registering with it.
  69 * It's best to check this at drm_dev_init(), as some drivers
  70 * prefer to embed struct drm_device into their own device
  71 * structure and call drm_dev_init() themselves.
  72 */
  73static bool drm_core_init_complete;
  74
  75DEFINE_STATIC_SRCU(drm_unplug_srcu);
  76
  77/*
  78 * DRM Minors
  79 * A DRM device can provide several char-dev interfaces on the DRM-Major. Each
  80 * of them is represented by a drm_minor object. Depending on the capabilities
  81 * of the device-driver, different interfaces are registered.
  82 *
  83 * Minors can be accessed via dev->$minor_name. This pointer is either
  84 * NULL or a valid drm_minor pointer and stays valid as long as the device is
  85 * valid. This means, DRM minors have the same life-time as the underlying
  86 * device. However, this doesn't mean that the minor is active. Minors are
  87 * registered and unregistered dynamically according to device-state.
  88 */
  89
  90static struct xarray *drm_minor_get_xa(enum drm_minor_type type)
  91{
  92	if (type == DRM_MINOR_PRIMARY || type == DRM_MINOR_RENDER)
  93		return &drm_minors_xa;
  94#if IS_ENABLED(CONFIG_DRM_ACCEL)
  95	else if (type == DRM_MINOR_ACCEL)
  96		return &accel_minors_xa;
  97#endif
  98	else
  99		return ERR_PTR(-EOPNOTSUPP);
 100}
 101
 102static struct drm_minor **drm_minor_get_slot(struct drm_device *dev,
 103					     enum drm_minor_type type)
 104{
 105	switch (type) {
 106	case DRM_MINOR_PRIMARY:
 107		return &dev->primary;
 108	case DRM_MINOR_RENDER:
 109		return &dev->render;
 110	case DRM_MINOR_ACCEL:
 111		return &dev->accel;
 112	default:
 113		BUG();
 114	}
 115}
 116
 117static void drm_minor_alloc_release(struct drm_device *dev, void *data)
 118{
 119	struct drm_minor *minor = data;
 120
 121	WARN_ON(dev != minor->dev);
 122
 123	put_device(minor->kdev);
 124
 125	xa_erase(drm_minor_get_xa(minor->type), minor->index);
 126}
 127
 128/*
 129 * DRM used to support 64 devices, for backwards compatibility we need to maintain the
 130 * minor allocation scheme where minors 0-63 are primary nodes, 64-127 are control nodes,
 131 * and 128-191 are render nodes.
 132 * After reaching the limit, we're allocating minors dynamically - first-come, first-serve.
 133 * Accel nodes are using a distinct major, so the minors are allocated in continuous 0-MAX
 134 * range.
 135 */
 136#define DRM_MINOR_LIMIT(t) ({ \
 137	typeof(t) _t = (t); \
 138	_t == DRM_MINOR_ACCEL ? XA_LIMIT(0, ACCEL_MAX_MINORS) : XA_LIMIT(64 * _t, 64 * _t + 63); \
 139})
 140#define DRM_EXTENDED_MINOR_LIMIT XA_LIMIT(192, (1 << MINORBITS) - 1)
 141
 142static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type)
 143{
 144	struct drm_minor *minor;
 145	int r;
 146
 147	minor = drmm_kzalloc(dev, sizeof(*minor), GFP_KERNEL);
 148	if (!minor)
 149		return -ENOMEM;
 150
 151	minor->type = type;
 152	minor->dev = dev;
 153
 154	r = xa_alloc(drm_minor_get_xa(type), &minor->index,
 155		     NULL, DRM_MINOR_LIMIT(type), GFP_KERNEL);
 156	if (r == -EBUSY && (type == DRM_MINOR_PRIMARY || type == DRM_MINOR_RENDER))
 157		r = xa_alloc(&drm_minors_xa, &minor->index,
 158			     NULL, DRM_EXTENDED_MINOR_LIMIT, GFP_KERNEL);
 159	if (r < 0)
 160		return r;
 161
 162	r = drmm_add_action_or_reset(dev, drm_minor_alloc_release, minor);
 163	if (r)
 164		return r;
 165
 166	minor->kdev = drm_sysfs_minor_alloc(minor);
 167	if (IS_ERR(minor->kdev))
 168		return PTR_ERR(minor->kdev);
 169
 170	*drm_minor_get_slot(dev, type) = minor;
 171	return 0;
 172}
 173
 174static int drm_minor_register(struct drm_device *dev, enum drm_minor_type type)
 175{
 176	struct drm_minor *minor;
 177	void *entry;
 178	int ret;
 179
 180	DRM_DEBUG("\n");
 181
 182	minor = *drm_minor_get_slot(dev, type);
 183	if (!minor)
 184		return 0;
 185
 186	if (minor->type != DRM_MINOR_ACCEL) {
 187		ret = drm_debugfs_register(minor, minor->index);
 188		if (ret) {
 189			DRM_ERROR("DRM: Failed to initialize /sys/kernel/debug/dri.\n");
 190			goto err_debugfs;
 191		}
 192	}
 193
 194	ret = device_add(minor->kdev);
 195	if (ret)
 196		goto err_debugfs;
 197
 198	/* replace NULL with @minor so lookups will succeed from now on */
 199	entry = xa_store(drm_minor_get_xa(type), minor->index, minor, GFP_KERNEL);
 200	if (xa_is_err(entry)) {
 201		ret = xa_err(entry);
 202		goto err_debugfs;
 203	}
 204	WARN_ON(entry);
 205
 206	DRM_DEBUG("new minor registered %d\n", minor->index);
 207	return 0;
 208
 209err_debugfs:
 210	drm_debugfs_unregister(minor);
 211	return ret;
 212}
 213
 214static void drm_minor_unregister(struct drm_device *dev, enum drm_minor_type type)
 215{
 216	struct drm_minor *minor;
 217
 218	minor = *drm_minor_get_slot(dev, type);
 219	if (!minor || !device_is_registered(minor->kdev))
 220		return;
 221
 222	/* replace @minor with NULL so lookups will fail from now on */
 223	xa_store(drm_minor_get_xa(type), minor->index, NULL, GFP_KERNEL);
 224
 225	device_del(minor->kdev);
 226	dev_set_drvdata(minor->kdev, NULL); /* safety belt */
 227	drm_debugfs_unregister(minor);
 228}
 229
 230/*
 231 * Looks up the given minor-ID and returns the respective DRM-minor object. The
 232 * refence-count of the underlying device is increased so you must release this
 233 * object with drm_minor_release().
 234 *
 235 * As long as you hold this minor, it is guaranteed that the object and the
 236 * minor->dev pointer will stay valid! However, the device may get unplugged and
 237 * unregistered while you hold the minor.
 238 */
 239struct drm_minor *drm_minor_acquire(struct xarray *minor_xa, unsigned int minor_id)
 240{
 241	struct drm_minor *minor;
 242
 243	xa_lock(minor_xa);
 244	minor = xa_load(minor_xa, minor_id);
 245	if (minor)
 246		drm_dev_get(minor->dev);
 247	xa_unlock(minor_xa);
 248
 249	if (!minor) {
 250		return ERR_PTR(-ENODEV);
 251	} else if (drm_dev_is_unplugged(minor->dev)) {
 252		drm_dev_put(minor->dev);
 253		return ERR_PTR(-ENODEV);
 254	}
 255
 256	return minor;
 257}
 258
 259void drm_minor_release(struct drm_minor *minor)
 260{
 261	drm_dev_put(minor->dev);
 262}
 263
 264/**
 265 * DOC: driver instance overview
 266 *
 267 * A device instance for a drm driver is represented by &struct drm_device. This
 268 * is allocated and initialized with devm_drm_dev_alloc(), usually from
 269 * bus-specific ->probe() callbacks implemented by the driver. The driver then
 270 * needs to initialize all the various subsystems for the drm device like memory
 271 * management, vblank handling, modesetting support and initial output
 272 * configuration plus obviously initialize all the corresponding hardware bits.
 273 * Finally when everything is up and running and ready for userspace the device
 274 * instance can be published using drm_dev_register().
 275 *
 276 * There is also deprecated support for initializing device instances using
 277 * bus-specific helpers and the &drm_driver.load callback. But due to
 278 * backwards-compatibility needs the device instance have to be published too
 279 * early, which requires unpretty global locking to make safe and is therefore
 280 * only support for existing drivers not yet converted to the new scheme.
 281 *
 282 * When cleaning up a device instance everything needs to be done in reverse:
 283 * First unpublish the device instance with drm_dev_unregister(). Then clean up
 284 * any other resources allocated at device initialization and drop the driver's
 285 * reference to &drm_device using drm_dev_put().
 286 *
 287 * Note that any allocation or resource which is visible to userspace must be
 288 * released only when the final drm_dev_put() is called, and not when the
 289 * driver is unbound from the underlying physical struct &device. Best to use
 290 * &drm_device managed resources with drmm_add_action(), drmm_kmalloc() and
 291 * related functions.
 292 *
 293 * devres managed resources like devm_kmalloc() can only be used for resources
 294 * directly related to the underlying hardware device, and only used in code
 295 * paths fully protected by drm_dev_enter() and drm_dev_exit().
 296 *
 297 * Display driver example
 298 * ~~~~~~~~~~~~~~~~~~~~~~
 299 *
 300 * The following example shows a typical structure of a DRM display driver.
 301 * The example focus on the probe() function and the other functions that is
 302 * almost always present and serves as a demonstration of devm_drm_dev_alloc().
 303 *
 304 * .. code-block:: c
 305 *
 306 *	struct driver_device {
 307 *		struct drm_device drm;
 308 *		void *userspace_facing;
 309 *		struct clk *pclk;
 310 *	};
 311 *
 312 *	static const struct drm_driver driver_drm_driver = {
 313 *		[...]
 314 *	};
 315 *
 316 *	static int driver_probe(struct platform_device *pdev)
 317 *	{
 318 *		struct driver_device *priv;
 319 *		struct drm_device *drm;
 320 *		int ret;
 321 *
 322 *		priv = devm_drm_dev_alloc(&pdev->dev, &driver_drm_driver,
 323 *					  struct driver_device, drm);
 324 *		if (IS_ERR(priv))
 325 *			return PTR_ERR(priv);
 326 *		drm = &priv->drm;
 327 *
 328 *		ret = drmm_mode_config_init(drm);
 329 *		if (ret)
 330 *			return ret;
 331 *
 332 *		priv->userspace_facing = drmm_kzalloc(..., GFP_KERNEL);
 333 *		if (!priv->userspace_facing)
 334 *			return -ENOMEM;
 335 *
 336 *		priv->pclk = devm_clk_get(dev, "PCLK");
 337 *		if (IS_ERR(priv->pclk))
 338 *			return PTR_ERR(priv->pclk);
 339 *
 340 *		// Further setup, display pipeline etc
 341 *
 342 *		platform_set_drvdata(pdev, drm);
 343 *
 344 *		drm_mode_config_reset(drm);
 345 *
 346 *		ret = drm_dev_register(drm);
 347 *		if (ret)
 348 *			return ret;
 349 *
 350 *		drm_fbdev_{...}_setup(drm, 32);
 351 *
 352 *		return 0;
 353 *	}
 354 *
 355 *	// This function is called before the devm_ resources are released
 356 *	static int driver_remove(struct platform_device *pdev)
 357 *	{
 358 *		struct drm_device *drm = platform_get_drvdata(pdev);
 359 *
 360 *		drm_dev_unregister(drm);
 361 *		drm_atomic_helper_shutdown(drm)
 362 *
 363 *		return 0;
 364 *	}
 365 *
 366 *	// This function is called on kernel restart and shutdown
 367 *	static void driver_shutdown(struct platform_device *pdev)
 368 *	{
 369 *		drm_atomic_helper_shutdown(platform_get_drvdata(pdev));
 370 *	}
 371 *
 372 *	static int __maybe_unused driver_pm_suspend(struct device *dev)
 373 *	{
 374 *		return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
 375 *	}
 376 *
 377 *	static int __maybe_unused driver_pm_resume(struct device *dev)
 378 *	{
 379 *		drm_mode_config_helper_resume(dev_get_drvdata(dev));
 380 *
 381 *		return 0;
 382 *	}
 383 *
 384 *	static const struct dev_pm_ops driver_pm_ops = {
 385 *		SET_SYSTEM_SLEEP_PM_OPS(driver_pm_suspend, driver_pm_resume)
 386 *	};
 387 *
 388 *	static struct platform_driver driver_driver = {
 389 *		.driver = {
 390 *			[...]
 391 *			.pm = &driver_pm_ops,
 392 *		},
 393 *		.probe = driver_probe,
 394 *		.remove = driver_remove,
 395 *		.shutdown = driver_shutdown,
 396 *	};
 397 *	module_platform_driver(driver_driver);
 398 *
 399 * Drivers that want to support device unplugging (USB, DT overlay unload) should
 400 * use drm_dev_unplug() instead of drm_dev_unregister(). The driver must protect
 401 * regions that is accessing device resources to prevent use after they're
 402 * released. This is done using drm_dev_enter() and drm_dev_exit(). There is one
 403 * shortcoming however, drm_dev_unplug() marks the drm_device as unplugged before
 404 * drm_atomic_helper_shutdown() is called. This means that if the disable code
 405 * paths are protected, they will not run on regular driver module unload,
 406 * possibly leaving the hardware enabled.
 407 */
 408
 409/**
 410 * drm_put_dev - Unregister and release a DRM device
 411 * @dev: DRM device
 412 *
 413 * Called at module unload time or when a PCI device is unplugged.
 414 *
 415 * Cleans up all DRM device, calling drm_lastclose().
 416 *
 417 * Note: Use of this function is deprecated. It will eventually go away
 418 * completely.  Please use drm_dev_unregister() and drm_dev_put() explicitly
 419 * instead to make sure that the device isn't userspace accessible any more
 420 * while teardown is in progress, ensuring that userspace can't access an
 421 * inconsistent state.
 422 */
 423void drm_put_dev(struct drm_device *dev)
 424{
 425	DRM_DEBUG("\n");
 426
 427	if (!dev) {
 428		DRM_ERROR("cleanup called no dev\n");
 429		return;
 430	}
 431
 432	drm_dev_unregister(dev);
 433	drm_dev_put(dev);
 434}
 435EXPORT_SYMBOL(drm_put_dev);
 436
 437/**
 438 * drm_dev_enter - Enter device critical section
 439 * @dev: DRM device
 440 * @idx: Pointer to index that will be passed to the matching drm_dev_exit()
 441 *
 442 * This function marks and protects the beginning of a section that should not
 443 * be entered after the device has been unplugged. The section end is marked
 444 * with drm_dev_exit(). Calls to this function can be nested.
 445 *
 446 * Returns:
 447 * True if it is OK to enter the section, false otherwise.
 448 */
 449bool drm_dev_enter(struct drm_device *dev, int *idx)
 450{
 451	*idx = srcu_read_lock(&drm_unplug_srcu);
 452
 453	if (dev->unplugged) {
 454		srcu_read_unlock(&drm_unplug_srcu, *idx);
 455		return false;
 456	}
 457
 458	return true;
 459}
 460EXPORT_SYMBOL(drm_dev_enter);
 461
 462/**
 463 * drm_dev_exit - Exit device critical section
 464 * @idx: index returned from drm_dev_enter()
 465 *
 466 * This function marks the end of a section that should not be entered after
 467 * the device has been unplugged.
 468 */
 469void drm_dev_exit(int idx)
 470{
 471	srcu_read_unlock(&drm_unplug_srcu, idx);
 472}
 473EXPORT_SYMBOL(drm_dev_exit);
 474
 475/**
 476 * drm_dev_unplug - unplug a DRM device
 477 * @dev: DRM device
 478 *
 479 * This unplugs a hotpluggable DRM device, which makes it inaccessible to
 480 * userspace operations. Entry-points can use drm_dev_enter() and
 481 * drm_dev_exit() to protect device resources in a race free manner. This
 482 * essentially unregisters the device like drm_dev_unregister(), but can be
 483 * called while there are still open users of @dev.
 484 */
 485void drm_dev_unplug(struct drm_device *dev)
 486{
 487	/*
 488	 * After synchronizing any critical read section is guaranteed to see
 489	 * the new value of ->unplugged, and any critical section which might
 490	 * still have seen the old value of ->unplugged is guaranteed to have
 491	 * finished.
 492	 */
 493	dev->unplugged = true;
 494	synchronize_srcu(&drm_unplug_srcu);
 495
 496	drm_dev_unregister(dev);
 497
 498	/* Clear all CPU mappings pointing to this device */
 499	unmap_mapping_range(dev->anon_inode->i_mapping, 0, 0, 1);
 500}
 501EXPORT_SYMBOL(drm_dev_unplug);
 502
 503/**
 504 * drm_dev_set_dma_dev - set the DMA device for a DRM device
 505 * @dev: DRM device
 506 * @dma_dev: DMA device or NULL
 507 *
 508 * Sets the DMA device of the given DRM device. Only required if
 509 * the DMA device is different from the DRM device's parent. After
 510 * calling this function, the DRM device holds a reference on
 511 * @dma_dev. Pass NULL to clear the DMA device.
 512 */
 513void drm_dev_set_dma_dev(struct drm_device *dev, struct device *dma_dev)
 514{
 515	dma_dev = get_device(dma_dev);
 516
 517	put_device(dev->dma_dev);
 518	dev->dma_dev = dma_dev;
 519}
 520EXPORT_SYMBOL(drm_dev_set_dma_dev);
 521
 522/*
 523 * Available recovery methods for wedged device. To be sent along with device
 524 * wedged uevent.
 525 */
 526static const char *drm_get_wedge_recovery(unsigned int opt)
 527{
 528	switch (BIT(opt)) {
 529	case DRM_WEDGE_RECOVERY_NONE:
 530		return "none";
 531	case DRM_WEDGE_RECOVERY_REBIND:
 532		return "rebind";
 533	case DRM_WEDGE_RECOVERY_BUS_RESET:
 534		return "bus-reset";
 535	case DRM_WEDGE_RECOVERY_VENDOR:
 536		return "vendor-specific";
 537	default:
 538		return NULL;
 539	}
 540}
 541
 542#define WEDGE_STR_LEN	32
 543#define PID_STR_LEN	15
 544#define COMM_STR_LEN	(TASK_COMM_LEN + 5)
 545
 546/**
 547 * drm_dev_wedged_event - generate a device wedged uevent
 548 * @dev: DRM device
 549 * @method: method(s) to be used for recovery
 550 * @info: optional information about the guilty task
 551 *
 552 * This generates a device wedged uevent for the DRM device specified by @dev.
 553 * Recovery @method\(s) of choice will be sent in the uevent environment as
 554 * ``WEDGED=<method1>[,..,<methodN>]`` in order of less to more side-effects.
 555 * If caller is unsure about recovery or @method is unknown (0),
 556 * ``WEDGED=unknown`` will be sent instead.
 557 *
 558 * Refer to "Device Wedging" chapter in Documentation/gpu/drm-uapi.rst for more
 559 * details.
 560 *
 561 * Returns: 0 on success, negative error code otherwise.
 562 */
 563int drm_dev_wedged_event(struct drm_device *dev, unsigned long method,
 564			 struct drm_wedge_task_info *info)
 565{
 566	char event_string[WEDGE_STR_LEN], pid_string[PID_STR_LEN], comm_string[COMM_STR_LEN];
 567	char *envp[] = { event_string, NULL, NULL, NULL };
 568	const char *recovery = NULL;
 569	unsigned int len, opt;
 570
 571	len = scnprintf(event_string, sizeof(event_string), "%s", "WEDGED=");
 572
 573	for_each_set_bit(opt, &method, BITS_PER_TYPE(method)) {
 574		recovery = drm_get_wedge_recovery(opt);
 575		if (drm_WARN_ONCE(dev, !recovery, "invalid recovery method %u\n", opt))
 576			break;
 577
 578		len += scnprintf(event_string + len, sizeof(event_string) - len, "%s,", recovery);
 579	}
 580
 581	if (recovery)
 582		/* Get rid of trailing comma */
 583		event_string[len - 1] = '\0';
 584	else
 585		/* Caller is unsure about recovery, do the best we can at this point. */
 586		snprintf(event_string, sizeof(event_string), "%s", "WEDGED=unknown");
 587
 588	drm_info(dev, "device wedged, %s\n", method == DRM_WEDGE_RECOVERY_NONE ?
 589		 "but recovered through reset" : "needs recovery");
 590
 591	if (info && (info->comm[0] != '\0') && (info->pid >= 0)) {
 592		snprintf(pid_string, sizeof(pid_string), "PID=%u", info->pid);
 593		snprintf(comm_string, sizeof(comm_string), "TASK=%s", info->comm);
 594		envp[1] = pid_string;
 595		envp[2] = comm_string;
 596	}
 597
 598	return kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE, envp);
 599}
 600EXPORT_SYMBOL(drm_dev_wedged_event);
 601
 602/*
 603 * DRM internal mount
 604 * We want to be able to allocate our own "struct address_space" to control
 605 * memory-mappings in VRAM (or stolen RAM, ...). However, core MM does not allow
 606 * stand-alone address_space objects, so we need an underlying inode. As there
 607 * is no way to allocate an independent inode easily, we need a fake internal
 608 * VFS mount-point.
 609 *
 610 * The drm_fs_inode_new() function allocates a new inode, drm_fs_inode_free()
 611 * frees it again. You are allowed to use iget() and iput() to get references to
 612 * the inode. But each drm_fs_inode_new() call must be paired with exactly one
 613 * drm_fs_inode_free() call (which does not have to be the last iput()).
 614 * We use drm_fs_inode_*() to manage our internal VFS mount-point and share it
 615 * between multiple inode-users. You could, technically, call
 616 * iget() + drm_fs_inode_free() directly after alloc and sometime later do an
 617 * iput(), but this way you'd end up with a new vfsmount for each inode.
 618 */
 619
 620static int drm_fs_cnt;
 621static struct vfsmount *drm_fs_mnt;
 622
 623static int drm_fs_init_fs_context(struct fs_context *fc)
 624{
 625	return init_pseudo(fc, 0x010203ff) ? 0 : -ENOMEM;
 626}
 627
 628static struct file_system_type drm_fs_type = {
 629	.name		= "drm",
 630	.owner		= THIS_MODULE,
 631	.init_fs_context = drm_fs_init_fs_context,
 632	.kill_sb	= kill_anon_super,
 633};
 634
 635static struct inode *drm_fs_inode_new(void)
 636{
 637	struct inode *inode;
 638	int r;
 639
 640	r = simple_pin_fs(&drm_fs_type, &drm_fs_mnt, &drm_fs_cnt);
 641	if (r < 0) {
 642		DRM_ERROR("Cannot mount pseudo fs: %d\n", r);
 643		return ERR_PTR(r);
 644	}
 645
 646	inode = alloc_anon_inode(drm_fs_mnt->mnt_sb);
 647	if (IS_ERR(inode))
 648		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
 649
 650	return inode;
 651}
 652
 653static void drm_fs_inode_free(struct inode *inode)
 654{
 655	if (inode) {
 656		iput(inode);
 657		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
 658	}
 659}
 660
 661/**
 662 * DOC: component helper usage recommendations
 663 *
 664 * DRM drivers that drive hardware where a logical device consists of a pile of
 665 * independent hardware blocks are recommended to use the :ref:`component helper
 666 * library<component>`. For consistency and better options for code reuse the
 667 * following guidelines apply:
 668 *
 669 *  - The entire device initialization procedure should be run from the
 670 *    &component_master_ops.master_bind callback, starting with
 671 *    devm_drm_dev_alloc(), then binding all components with
 672 *    component_bind_all() and finishing with drm_dev_register().
 673 *
 674 *  - The opaque pointer passed to all components through component_bind_all()
 675 *    should point at &struct drm_device of the device instance, not some driver
 676 *    specific private structure.
 677 *
 678 *  - The component helper fills the niche where further standardization of
 679 *    interfaces is not practical. When there already is, or will be, a
 680 *    standardized interface like &drm_bridge or &drm_panel, providing its own
 681 *    functions to find such components at driver load time, like
 682 *    drm_of_find_panel_or_bridge(), then the component helper should not be
 683 *    used.
 684 */
 685
 686static void drm_dev_init_release(struct drm_device *dev, void *res)
 687{
 688	drm_fs_inode_free(dev->anon_inode);
 689
 690	put_device(dev->dma_dev);
 691	dev->dma_dev = NULL;
 692	put_device(dev->dev);
 693	/* Prevent use-after-free in drm_managed_release when debugging is
 694	 * enabled. Slightly awkward, but can't really be helped. */
 695	dev->dev = NULL;
 696	mutex_destroy(&dev->master_mutex);
 697	mutex_destroy(&dev->clientlist_mutex);
 698	mutex_destroy(&dev->filelist_mutex);
 699}
 700
 701static int drm_dev_init(struct drm_device *dev,
 702			const struct drm_driver *driver,
 703			struct device *parent)
 704{
 705	struct inode *inode;
 706	int ret;
 707
 708	if (!drm_core_init_complete) {
 709		DRM_ERROR("DRM core is not initialized\n");
 710		return -ENODEV;
 711	}
 712
 713	if (WARN_ON(!parent))
 714		return -EINVAL;
 715
 716	kref_init(&dev->ref);
 717	dev->dev = get_device(parent);
 718	dev->driver = driver;
 719
 720	INIT_LIST_HEAD(&dev->managed.resources);
 721	spin_lock_init(&dev->managed.lock);
 722
 723	/* no per-device feature limits by default */
 724	dev->driver_features = ~0u;
 725
 726	if (drm_core_check_feature(dev, DRIVER_COMPUTE_ACCEL) &&
 727				(drm_core_check_feature(dev, DRIVER_RENDER) ||
 728				drm_core_check_feature(dev, DRIVER_MODESET))) {
 729		DRM_ERROR("DRM driver can't be both a compute acceleration and graphics driver\n");
 730		return -EINVAL;
 731	}
 732
 733	INIT_LIST_HEAD(&dev->filelist);
 734	INIT_LIST_HEAD(&dev->filelist_internal);
 735	INIT_LIST_HEAD(&dev->clientlist);
 736	INIT_LIST_HEAD(&dev->client_sysrq_list);
 737	INIT_LIST_HEAD(&dev->vblank_event_list);
 738
 739	spin_lock_init(&dev->event_lock);
 740	mutex_init(&dev->filelist_mutex);
 741	mutex_init(&dev->clientlist_mutex);
 742	mutex_init(&dev->master_mutex);
 743	raw_spin_lock_init(&dev->mode_config.panic_lock);
 744
 745	ret = drmm_add_action_or_reset(dev, drm_dev_init_release, NULL);
 746	if (ret)
 747		return ret;
 748
 749	inode = drm_fs_inode_new();
 750	if (IS_ERR(inode)) {
 751		ret = PTR_ERR(inode);
 752		DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
 753		goto err;
 754	}
 755
 756	dev->anon_inode = inode;
 757
 758	if (drm_core_check_feature(dev, DRIVER_COMPUTE_ACCEL)) {
 759		ret = drm_minor_alloc(dev, DRM_MINOR_ACCEL);
 760		if (ret)
 761			goto err;
 762	} else {
 763		if (drm_core_check_feature(dev, DRIVER_RENDER)) {
 764			ret = drm_minor_alloc(dev, DRM_MINOR_RENDER);
 765			if (ret)
 766				goto err;
 767		}
 768
 769		ret = drm_minor_alloc(dev, DRM_MINOR_PRIMARY);
 770		if (ret)
 771			goto err;
 772	}
 773
 774	if (drm_core_check_feature(dev, DRIVER_GEM)) {
 775		ret = drm_gem_init(dev);
 776		if (ret) {
 777			DRM_ERROR("Cannot initialize graphics execution manager (GEM)\n");
 778			goto err;
 779		}
 780	}
 781
 782	dev->unique = drmm_kstrdup(dev, dev_name(parent), GFP_KERNEL);
 783	if (!dev->unique) {
 784		ret = -ENOMEM;
 785		goto err;
 786	}
 787
 788	drm_debugfs_dev_init(dev);
 789
 790	return 0;
 791
 792err:
 793	drm_managed_release(dev);
 794
 795	return ret;
 796}
 797
 798static void devm_drm_dev_init_release(void *data)
 799{
 800	drm_dev_put(data);
 801}
 802
 803static int devm_drm_dev_init(struct device *parent,
 804			     struct drm_device *dev,
 805			     const struct drm_driver *driver)
 806{
 807	int ret;
 808
 809	ret = drm_dev_init(dev, driver, parent);
 810	if (ret)
 811		return ret;
 812
 813	return devm_add_action_or_reset(parent,
 814					devm_drm_dev_init_release, dev);
 815}
 816
 817void *__devm_drm_dev_alloc(struct device *parent,
 818			   const struct drm_driver *driver,
 819			   size_t size, size_t offset)
 820{
 821	void *container;
 822	struct drm_device *drm;
 823	int ret;
 824
 825	container = kzalloc(size, GFP_KERNEL);
 826	if (!container)
 827		return ERR_PTR(-ENOMEM);
 828
 829	drm = container + offset;
 830	ret = devm_drm_dev_init(parent, drm, driver);
 831	if (ret) {
 832		kfree(container);
 833		return ERR_PTR(ret);
 834	}
 835	drmm_add_final_kfree(drm, container);
 836
 837	return container;
 838}
 839EXPORT_SYMBOL(__devm_drm_dev_alloc);
 840
 841/**
 842 * __drm_dev_alloc - Allocation of a &drm_device instance
 843 * @parent: Parent device object
 844 * @driver: DRM driver
 845 * @size: the size of the struct which contains struct drm_device
 846 * @offset: the offset of the &drm_device within the container.
 847 *
 848 * This should *NOT* be by any drivers, but is a dedicated interface for the
 849 * corresponding Rust abstraction.
 850 *
 851 * This is the same as devm_drm_dev_alloc(), but without the corresponding
 852 * resource management through the parent device, but not the same as
 853 * drm_dev_alloc(), since the latter is the deprecated version, which does not
 854 * support subclassing.
 855 *
 856 * Returns: A pointer to new DRM device, or an ERR_PTR on failure.
 857 */
 858void *__drm_dev_alloc(struct device *parent,
 859		      const struct drm_driver *driver,
 860		      size_t size, size_t offset)
 861{
 862	void *container;
 863	struct drm_device *drm;
 864	int ret;
 865
 866	container = kzalloc(size, GFP_KERNEL);
 867	if (!container)
 868		return ERR_PTR(-ENOMEM);
 869
 870	drm = container + offset;
 871	ret = drm_dev_init(drm, driver, parent);
 872	if (ret) {
 873		kfree(container);
 874		return ERR_PTR(ret);
 875	}
 876	drmm_add_final_kfree(drm, container);
 877
 878	return container;
 879}
 880EXPORT_SYMBOL(__drm_dev_alloc);
 881
 882/**
 883 * drm_dev_alloc - Allocate new DRM device
 884 * @driver: DRM driver to allocate device for
 885 * @parent: Parent device object
 886 *
 887 * This is the deprecated version of devm_drm_dev_alloc(), which does not support
 888 * subclassing through embedding the struct &drm_device in a driver private
 889 * structure, and which does not support automatic cleanup through devres.
 890 *
 891 * RETURNS:
 892 * Pointer to new DRM device, or ERR_PTR on failure.
 893 */
 894struct drm_device *drm_dev_alloc(const struct drm_driver *driver,
 895				 struct device *parent)
 896{
 897	return __drm_dev_alloc(parent, driver, sizeof(struct drm_device), 0);
 898}
 899EXPORT_SYMBOL(drm_dev_alloc);
 900
 901static void drm_dev_release(struct kref *ref)
 902{
 903	struct drm_device *dev = container_of(ref, struct drm_device, ref);
 904
 905	/* Just in case register/unregister was never called */
 906	drm_debugfs_dev_fini(dev);
 907
 908	if (dev->driver->release)
 909		dev->driver->release(dev);
 910
 911	drm_managed_release(dev);
 912
 913	kfree(dev->managed.final_kfree);
 914}
 915
 916/**
 917 * drm_dev_get - Take reference of a DRM device
 918 * @dev: device to take reference of or NULL
 919 *
 920 * This increases the ref-count of @dev by one. You *must* already own a
 921 * reference when calling this. Use drm_dev_put() to drop this reference
 922 * again.
 923 *
 924 * This function never fails. However, this function does not provide *any*
 925 * guarantee whether the device is alive or running. It only provides a
 926 * reference to the object and the memory associated with it.
 927 */
 928void drm_dev_get(struct drm_device *dev)
 929{
 930	if (dev)
 931		kref_get(&dev->ref);
 932}
 933EXPORT_SYMBOL(drm_dev_get);
 934
 935/**
 936 * drm_dev_put - Drop reference of a DRM device
 937 * @dev: device to drop reference of or NULL
 938 *
 939 * This decreases the ref-count of @dev by one. The device is destroyed if the
 940 * ref-count drops to zero.
 941 */
 942void drm_dev_put(struct drm_device *dev)
 943{
 944	if (dev)
 945		kref_put(&dev->ref, drm_dev_release);
 946}
 947EXPORT_SYMBOL(drm_dev_put);
 948
 949static void drmm_cg_unregister_region(struct drm_device *dev, void *arg)
 950{
 951	dmem_cgroup_unregister_region(arg);
 952}
 953
 954/**
 955 * drmm_cgroup_register_region - Register a region of a DRM device to cgroups
 956 * @dev: device for region
 957 * @region_name: Region name for registering
 958 * @size: Size of region in bytes
 959 *
 960 * This decreases the ref-count of @dev by one. The device is destroyed if the
 961 * ref-count drops to zero.
 962 */
 963struct dmem_cgroup_region *drmm_cgroup_register_region(struct drm_device *dev, const char *region_name, u64 size)
 964{
 965	struct dmem_cgroup_region *region;
 966	int ret;
 967
 968	region = dmem_cgroup_register_region(size, "drm/%s/%s", dev->unique, region_name);
 969	if (IS_ERR_OR_NULL(region))
 970		return region;
 971
 972	ret = drmm_add_action_or_reset(dev, drmm_cg_unregister_region, region);
 973	if (ret)
 974		return ERR_PTR(ret);
 975
 976	return region;
 977}
 978EXPORT_SYMBOL_GPL(drmm_cgroup_register_region);
 979
 980static int create_compat_control_link(struct drm_device *dev)
 981{
 982	struct drm_minor *minor;
 983	char *name;
 984	int ret;
 985
 986	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 987		return 0;
 988
 989	minor = *drm_minor_get_slot(dev, DRM_MINOR_PRIMARY);
 990	if (!minor)
 991		return 0;
 992
 993	/*
 994	 * Some existing userspace out there uses the existing of the controlD*
 995	 * sysfs files to figure out whether it's a modeset driver. It only does
 996	 * readdir, hence a symlink is sufficient (and the least confusing
 997	 * option). Otherwise controlD* is entirely unused.
 998	 *
 999	 * Old controlD chardev have been allocated in the range
1000	 * 64-127.
1001	 */
1002	name = kasprintf(GFP_KERNEL, "controlD%d", minor->index + 64);
1003	if (!name)
1004		return -ENOMEM;
1005
1006	ret = sysfs_create_link(minor->kdev->kobj.parent,
1007				&minor->kdev->kobj,
1008				name);
1009
1010	kfree(name);
1011
1012	return ret;
1013}
1014
1015static void remove_compat_control_link(struct drm_device *dev)
1016{
1017	struct drm_minor *minor;
1018	char *name;
1019
1020	if (!drm_core_check_feature(dev, DRIVER_MODESET))
1021		return;
1022
1023	minor = *drm_minor_get_slot(dev, DRM_MINOR_PRIMARY);
1024	if (!minor)
1025		return;
1026
1027	name = kasprintf(GFP_KERNEL, "controlD%d", minor->index + 64);
1028	if (!name)
1029		return;
1030
1031	sysfs_remove_link(minor->kdev->kobj.parent, name);
1032
1033	kfree(name);
1034}
1035
1036/**
1037 * drm_dev_register - Register DRM device
1038 * @dev: Device to register
1039 * @flags: Flags passed to the driver's .load() function
1040 *
1041 * Register the DRM device @dev with the system, advertise device to user-space
1042 * and start normal device operation. @dev must be initialized via drm_dev_init()
1043 * previously.
1044 *
1045 * Never call this twice on any device!
1046 *
1047 * NOTE: To ensure backward compatibility with existing drivers method this
1048 * function calls the &drm_driver.load method after registering the device
1049 * nodes, creating race conditions. Usage of the &drm_driver.load methods is
1050 * therefore deprecated, drivers must perform all initialization before calling
1051 * drm_dev_register().
1052 *
1053 * RETURNS:
1054 * 0 on success, negative error code on failure.
1055 */
1056int drm_dev_register(struct drm_device *dev, unsigned long flags)
1057{
1058	const struct drm_driver *driver = dev->driver;
1059	int ret;
1060
1061	if (!driver->load)
1062		drm_mode_config_validate(dev);
1063
1064	WARN_ON(!dev->managed.final_kfree);
1065
1066	if (drm_dev_needs_global_mutex(dev))
1067		mutex_lock(&drm_global_mutex);
1068
1069	if (drm_core_check_feature(dev, DRIVER_COMPUTE_ACCEL))
1070		accel_debugfs_register(dev);
1071	else
1072		drm_debugfs_dev_register(dev);
1073
1074	ret = drm_minor_register(dev, DRM_MINOR_RENDER);
1075	if (ret)
1076		goto err_minors;
1077
1078	ret = drm_minor_register(dev, DRM_MINOR_PRIMARY);
1079	if (ret)
1080		goto err_minors;
1081
1082	ret = drm_minor_register(dev, DRM_MINOR_ACCEL);
1083	if (ret)
1084		goto err_minors;
1085
1086	ret = create_compat_control_link(dev);
1087	if (ret)
1088		goto err_minors;
1089
1090	dev->registered = true;
1091
1092	if (driver->load) {
1093		ret = driver->load(dev, flags);
1094		if (ret)
1095			goto err_minors;
1096	}
1097
1098	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
1099		ret = drm_modeset_register_all(dev);
1100		if (ret)
1101			goto err_unload;
1102	}
1103	drm_panic_register(dev);
1104	drm_client_sysrq_register(dev);
1105
1106	DRM_INFO("Initialized %s %d.%d.%d for %s on minor %d\n",
1107		 driver->name, driver->major, driver->minor,
1108		 driver->patchlevel,
1109		 dev->dev ? dev_name(dev->dev) : "virtual device",
1110		 dev->primary ? dev->primary->index : dev->accel->index);
1111
1112	goto out_unlock;
1113
1114err_unload:
1115	if (dev->driver->unload)
1116		dev->driver->unload(dev);
1117err_minors:
1118	remove_compat_control_link(dev);
1119	drm_minor_unregister(dev, DRM_MINOR_ACCEL);
1120	drm_minor_unregister(dev, DRM_MINOR_PRIMARY);
1121	drm_minor_unregister(dev, DRM_MINOR_RENDER);
1122out_unlock:
1123	if (drm_dev_needs_global_mutex(dev))
1124		mutex_unlock(&drm_global_mutex);
1125	return ret;
1126}
1127EXPORT_SYMBOL(drm_dev_register);
1128
1129/**
1130 * drm_dev_unregister - Unregister DRM device
1131 * @dev: Device to unregister
1132 *
1133 * Unregister the DRM device from the system. This does the reverse of
1134 * drm_dev_register() but does not deallocate the device. The caller must call
1135 * drm_dev_put() to drop their final reference, unless it is managed with devres
1136 * (as devices allocated with devm_drm_dev_alloc() are), in which case there is
1137 * already an unwind action registered.
1138 *
1139 * A special form of unregistering for hotpluggable devices is drm_dev_unplug(),
1140 * which can be called while there are still open users of @dev.
1141 *
1142 * This should be called first in the device teardown code to make sure
1143 * userspace can't access the device instance any more.
1144 */
1145void drm_dev_unregister(struct drm_device *dev)
1146{
1147	dev->registered = false;
1148
1149	drm_client_sysrq_unregister(dev);
1150	drm_panic_unregister(dev);
1151
1152	drm_client_dev_unregister(dev);
1153
1154	if (drm_core_check_feature(dev, DRIVER_MODESET))
1155		drm_modeset_unregister_all(dev);
1156
1157	if (dev->driver->unload)
1158		dev->driver->unload(dev);
1159
1160	remove_compat_control_link(dev);
1161	drm_minor_unregister(dev, DRM_MINOR_ACCEL);
1162	drm_minor_unregister(dev, DRM_MINOR_PRIMARY);
1163	drm_minor_unregister(dev, DRM_MINOR_RENDER);
1164	drm_debugfs_dev_fini(dev);
1165}
1166EXPORT_SYMBOL(drm_dev_unregister);
1167
1168/*
1169 * DRM Core
1170 * The DRM core module initializes all global DRM objects and makes them
1171 * available to drivers. Once setup, drivers can probe their respective
1172 * devices.
1173 * Currently, core management includes:
1174 *  - The "DRM-Global" key/value database
1175 *  - Global ID management for connectors
1176 *  - DRM major number allocation
1177 *  - DRM minor management
1178 *  - DRM sysfs class
1179 *  - DRM debugfs root
1180 *
1181 * Furthermore, the DRM core provides dynamic char-dev lookups. For each
1182 * interface registered on a DRM device, you can request minor numbers from DRM
1183 * core. DRM core takes care of major-number management and char-dev
1184 * registration. A stub ->open() callback forwards any open() requests to the
1185 * registered minor.
1186 */
1187
1188static int drm_stub_open(struct inode *inode, struct file *filp)
1189{
1190	const struct file_operations *new_fops;
1191	struct drm_minor *minor;
1192	int err;
1193
1194	DRM_DEBUG("\n");
1195
1196	minor = drm_minor_acquire(&drm_minors_xa, iminor(inode));
1197	if (IS_ERR(minor))
1198		return PTR_ERR(minor);
1199
1200	new_fops = fops_get(minor->dev->driver->fops);
1201	if (!new_fops) {
1202		err = -ENODEV;
1203		goto out;
1204	}
1205
1206	replace_fops(filp, new_fops);
1207	if (filp->f_op->open)
1208		err = filp->f_op->open(inode, filp);
1209	else
1210		err = 0;
1211
1212out:
1213	drm_minor_release(minor);
1214
1215	return err;
1216}
1217
1218static const struct file_operations drm_stub_fops = {
1219	.owner = THIS_MODULE,
1220	.open = drm_stub_open,
1221	.llseek = noop_llseek,
1222};
1223
1224static void drm_core_exit(void)
1225{
1226	drm_privacy_screen_lookup_exit();
1227	drm_panic_exit();
1228	accel_core_exit();
1229	unregister_chrdev(DRM_MAJOR, "drm");
1230	drm_debugfs_remove_root();
1231	drm_sysfs_destroy();
1232	WARN_ON(!xa_empty(&drm_minors_xa));
1233	drm_connector_ida_destroy();
1234}
1235
1236static int __init drm_core_init(void)
1237{
1238	int ret;
1239
1240	drm_connector_ida_init();
1241	drm_memcpy_init_early();
1242
1243	ret = drm_sysfs_init();
1244	if (ret < 0) {
1245		DRM_ERROR("Cannot create DRM class: %d\n", ret);
1246		goto error;
1247	}
1248
1249	drm_debugfs_init_root();
1250	drm_debugfs_bridge_params();
1251
1252	ret = register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops);
1253	if (ret < 0)
1254		goto error;
1255
1256	ret = accel_core_init();
1257	if (ret < 0)
1258		goto error;
1259
1260	drm_panic_init();
1261
1262	drm_privacy_screen_lookup_init();
1263
1264	drm_core_init_complete = true;
1265
1266	DRM_DEBUG("Initialized\n");
1267	return 0;
1268
1269error:
1270	drm_core_exit();
1271	return ret;
1272}
1273
1274module_init(drm_core_init);
1275module_exit(drm_core_exit);