include/media/media-request.h

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Media device request objects
   4  *
   5  * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   6  * Copyright (C) 2018 Intel Corporation
   7  *
   8  * Author: Hans Verkuil <hans.verkuil@cisco.com>
   9  * Author: Sakari Ailus <sakari.ailus@linux.intel.com>
  10  */
  11
  12 #ifndef MEDIA_REQUEST_H
  13 #define MEDIA_REQUEST_H
  14
  15 #include <linux/list.h>
  16 #include <linux/slab.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/refcount.h>
  19
  20 #include <media/media-device.h>
  21
  22 /**
  23  * enum media_request_state - media request state
  24  *
  25  * @MEDIA_REQUEST_STATE_IDLE:           Idle
  26  * @MEDIA_REQUEST_STATE_VALIDATING:     Validating the request, no state changes
  27  *                                      allowed
  28  * @MEDIA_REQUEST_STATE_QUEUED:         Queued
  29  * @MEDIA_REQUEST_STATE_COMPLETE:       Completed, the request is done
  30  * @MEDIA_REQUEST_STATE_CLEANING:       Cleaning, the request is being re-inited
  31  * @MEDIA_REQUEST_STATE_UPDATING:       The request is being updated, i.e.
  32  *                                      request objects are being added,
  33  *                                      modified or removed
  34  * @NR_OF_MEDIA_REQUEST_STATE:          The number of media request states, used
  35  *                                      internally for sanity check purposes
  36  */
  37 enum media_request_state {
  38         MEDIA_REQUEST_STATE_IDLE,
  39         MEDIA_REQUEST_STATE_VALIDATING,
  40         MEDIA_REQUEST_STATE_QUEUED,
  41         MEDIA_REQUEST_STATE_COMPLETE,
  42         MEDIA_REQUEST_STATE_CLEANING,
  43         MEDIA_REQUEST_STATE_UPDATING,
  44         NR_OF_MEDIA_REQUEST_STATE,
  45 };
  46
  47 struct media_request_object;
  48
  49 /**
  50  * struct media_request - Media device request
  51  * @mdev: Media device this request belongs to
  52  * @kref: Reference count
  53  * @debug_str: Prefix for debug messages (process name:fd)
  54  * @state: The state of the request
  55  * @updating_count: count the number of request updates that are in progress
  56  * @access_count: count the number of request accesses that are in progress
  57  * @objects: List of @struct media_request_object request objects
  58  * @num_incomplete_objects: The number of incomplete objects in the request
  59  * @poll_wait: Wait queue for poll
  60  * @lock: Serializes access to this struct
  61  */
  62 struct media_request {
  63         struct media_device *mdev;
  64         struct kref kref;
  65         char debug_str[TASK_COMM_LEN + 11];
  66         enum media_request_state state;
  67         unsigned int updating_count;
  68         unsigned int access_count;
  69         struct list_head objects;
  70         unsigned int num_incomplete_objects;
  71         wait_queue_head_t poll_wait;
  72         spinlock_t lock;
  73 };
  74
  75 #ifdef CONFIG_MEDIA_CONTROLLER
  76
  77 /**
  78  * media_request_lock_for_access - Lock the request to access its objects
  79  *
  80  * @req: The media request
  81  *
  82  * Use before accessing a completed request. A reference to the request must
  83  * be held during the access. This usually takes place automatically through
  84  * a file handle. Use @media_request_unlock_for_access when done.
  85  */
  86 static inline int __must_check
  87 media_request_lock_for_access(struct media_request *req)
  88 {
  89         unsigned long flags;
  90         int ret = -EBUSY;
  91
  92         spin_lock_irqsave(&req->lock, flags);
  93         if (req->state == MEDIA_REQUEST_STATE_COMPLETE) {
  94                 req->access_count++;
  95                 ret = 0;
  96         }
  97         spin_unlock_irqrestore(&req->lock, flags);
  98
  99         return ret;
 100 }
 101
 102 /**
 103  * media_request_unlock_for_access - Unlock a request previously locked for
 104  *                                   access
 105  *
 106  * @req: The media request
 107  *
 108  * Unlock a request that has previously been locked using
 109  * @media_request_lock_for_access.
 110  */
 111 static inline void media_request_unlock_for_access(struct media_request *req)
 112 {
 113         unsigned long flags;
 114
 115         spin_lock_irqsave(&req->lock, flags);
 116         if (!WARN_ON(!req->access_count))
 117                 req->access_count--;
 118         spin_unlock_irqrestore(&req->lock, flags);
 119 }
 120
 121 /**
 122  * media_request_lock_for_update - Lock the request for updating its objects
 123  *
 124  * @req: The media request
 125  *
 126  * Use before updating a request, i.e. adding, modifying or removing a request
 127  * object in it. A reference to the request must be held during the update. This
 128  * usually takes place automatically through a file handle. Use
 129  * @media_request_unlock_for_update when done.
 130  */
 131 static inline int __must_check
 132 media_request_lock_for_update(struct media_request *req)
 133 {
 134         unsigned long flags;
 135         int ret = 0;
 136
 137         spin_lock_irqsave(&req->lock, flags);
 138         if (req->state == MEDIA_REQUEST_STATE_IDLE ||
 139             req->state == MEDIA_REQUEST_STATE_UPDATING) {
 140                 req->state = MEDIA_REQUEST_STATE_UPDATING;
 141                 req->updating_count++;
 142         } else {
 143                 ret = -EBUSY;
 144         }
 145         spin_unlock_irqrestore(&req->lock, flags);
 146
 147         return ret;
 148 }
 149
 150 /**
 151  * media_request_unlock_for_update - Unlock a request previously locked for
 152  *                                   update
 153  *
 154  * @req: The media request
 155  *
 156  * Unlock a request that has previously been locked using
 157  * @media_request_lock_for_update.
 158  */
 159 static inline void media_request_unlock_for_update(struct media_request *req)
 160 {
 161         unsigned long flags;
 162
 163         spin_lock_irqsave(&req->lock, flags);
 164         WARN_ON(req->updating_count <= 0);
 165         if (!--req->updating_count)
 166                 req->state = MEDIA_REQUEST_STATE_IDLE;
 167         spin_unlock_irqrestore(&req->lock, flags);
 168 }
 169
 170 /**
 171  * media_request_get - Get the media request
 172  *
 173  * @req: The media request
 174  *
 175  * Get the media request.
 176  */
 177 static inline void media_request_get(struct media_request *req)
 178 {
 179         kref_get(&req->kref);
 180 }
 181
 182 /**
 183  * media_request_put - Put the media request
 184  *
 185  * @req: The media request
 186  *
 187  * Put the media request. The media request will be released
 188  * when the refcount reaches 0.
 189  */
 190 void media_request_put(struct media_request *req);
 191
 192 /**
 193  * media_request_get_by_fd - Get a media request by fd
 194  *
 195  * @mdev: Media device this request belongs to
 196  * @request_fd: The file descriptor of the request
 197  *
 198  * Get the request represented by @request_fd that is owned
 199  * by the media device.
 200  *
 201  * Return a -EACCES error pointer if requests are not supported
 202  * by this driver. Return -EINVAL if the request was not found.
 203  * Return the pointer to the request if found: the caller will
 204  * have to call @media_request_put when it finished using the
 205  * request.
 206  */
 207 struct media_request *
 208 media_request_get_by_fd(struct media_device *mdev, int request_fd);
 209
 210 /**
 211  * media_request_alloc - Allocate the media request
 212  *
 213  * @mdev: Media device this request belongs to
 214  * @alloc_fd: Store the request's file descriptor in this int
 215  *
 216  * Allocated the media request and put the fd in @alloc_fd.
 217  */
 218 int media_request_alloc(struct media_device *mdev,
 219                         int *alloc_fd);
 220
 221 #else
 222
 223 static inline void media_request_get(struct media_request *req)
 224 {
 225 }
 226
 227 static inline void media_request_put(struct media_request *req)
 228 {
 229 }
 230
 231 static inline struct media_request *
 232 media_request_get_by_fd(struct media_device *mdev, int request_fd)
 233 {
 234         return ERR_PTR(-EACCES);
 235 }
 236
 237 #endif
 238
 239 /**
 240  * struct media_request_object_ops - Media request object operations
 241  * @prepare: Validate and prepare the request object, optional.
 242  * @unprepare: Unprepare the request object, optional.
 243  * @queue: Queue the request object, optional.
 244  * @unbind: Unbind the request object, optional.
 245  * @release: Release the request object, required.
 246  */
 247 struct media_request_object_ops {
 248         int (*prepare)(struct media_request_object *object);
 249         void (*unprepare)(struct media_request_object *object);
 250         void (*queue)(struct media_request_object *object);
 251         void (*unbind)(struct media_request_object *object);
 252         void (*release)(struct media_request_object *object);
 253 };
 254
 255 /**
 256  * struct media_request_object - An opaque object that belongs to a media
 257  *                               request
 258  *
 259  * @ops: object's operations
 260  * @priv: object's priv pointer
 261  * @req: the request this object belongs to (can be NULL)
 262  * @list: List entry of the object for @struct media_request
 263  * @kref: Reference count of the object, acquire before releasing req->lock
 264  * @completed: If true, then this object was completed.
 265  *
 266  * An object related to the request. This struct is always embedded in
 267  * another struct that contains the actual data for this request object.
 268  */
 269 struct media_request_object {
 270         const struct media_request_object_ops *ops;
 271         void *priv;
 272         struct media_request *req;
 273         struct list_head list;
 274         struct kref kref;
 275         bool completed;
 276 };
 277
 278 #ifdef CONFIG_MEDIA_CONTROLLER
 279
 280 /**
 281  * media_request_object_get - Get a media request object
 282  *
 283  * @obj: The object
 284  *
 285  * Get a media request object.
 286  */
 287 static inline void media_request_object_get(struct media_request_object *obj)
 288 {
 289         kref_get(&obj->kref);
 290 }
 291
 292 /**
 293  * media_request_object_put - Put a media request object
 294  *
 295  * @obj: The object
 296  *
 297  * Put a media request object. Once all references are gone, the
 298  * object's memory is released.
 299  */
 300 void media_request_object_put(struct media_request_object *obj);
 301
 302 /**
 303  * media_request_object_find - Find an object in a request
 304  *
 305  * @req: The media request
 306  * @ops: Find an object with this ops value
 307  * @priv: Find an object with this priv value
 308  *
 309  * Both @ops and @priv must be non-NULL.
 310  *
 311  * Returns the object pointer or NULL if not found. The caller must
 312  * call media_request_object_put() once it finished using the object.
 313  *
 314  * Since this function needs to walk the list of objects it takes
 315  * the @req->lock spin lock to make this safe.
 316  */
 317 struct media_request_object *
 318 media_request_object_find(struct media_request *req,
 319                           const struct media_request_object_ops *ops,
 320                           void *priv);
 321
 322 /**
 323  * media_request_object_init - Initialise a media request object
 324  *
 325  * @obj: The object
 326  *
 327  * Initialise a media request object. The object will be released using the
 328  * release callback of the ops once it has no references (this function
 329  * initialises references to one).
 330  */
 331 void media_request_object_init(struct media_request_object *obj);
 332
 333 /**
 334  * media_request_object_bind - Bind a media request object to a request
 335  *
 336  * @req: The media request
 337  * @ops: The object ops for this object
 338  * @priv: A driver-specific priv pointer associated with this object
 339  * @is_buffer: Set to true if the object a buffer object.
 340  * @obj: The object
 341  *
 342  * Bind this object to the request and set the ops and priv values of
 343  * the object so it can be found later with media_request_object_find().
 344  *
 345  * Every bound object must be unbound or completed by the kernel at some
 346  * point in time, otherwise the request will never complete. When the
 347  * request is released all completed objects will be unbound by the
 348  * request core code.
 349  *
 350  * Buffer objects will be added to the end of the request's object
 351  * list, non-buffer objects will be added to the front of the list.
 352  * This ensures that all buffer objects are at the end of the list
 353  * and that all non-buffer objects that they depend on are processed
 354  * first.
 355  */
 356 int media_request_object_bind(struct media_request *req,
 357                               const struct media_request_object_ops *ops,
 358                               void *priv, bool is_buffer,
 359                               struct media_request_object *obj);
 360
 361 /**
 362  * media_request_object_unbind - Unbind a media request object
 363  *
 364  * @obj: The object
 365  *
 366  * Unbind the media request object from the request.
 367  */
 368 void media_request_object_unbind(struct media_request_object *obj);
 369
 370 /**
 371  * media_request_object_complete - Mark the media request object as complete
 372  *
 373  * @obj: The object
 374  *
 375  * Mark the media request object as complete. Only bound objects can
 376  * be completed.
 377  */
 378 void media_request_object_complete(struct media_request_object *obj);
 379
 380 #else
 381
 382 static inline int __must_check
 383 media_request_lock_for_access(struct media_request *req)
 384 {
 385         return -EINVAL;
 386 }
 387
 388 static inline void media_request_unlock_for_access(struct media_request *req)
 389 {
 390 }
 391
 392 static inline int __must_check
 393 media_request_lock_for_update(struct media_request *req)
 394 {
 395         return -EINVAL;
 396 }
 397
 398 static inline void media_request_unlock_for_update(struct media_request *req)
 399 {
 400 }
 401
 402 static inline void media_request_object_get(struct media_request_object *obj)
 403 {
 404 }
 405
 406 static inline void media_request_object_put(struct media_request_object *obj)
 407 {
 408 }
 409
 410 static inline struct media_request_object *
 411 media_request_object_find(struct media_request *req,
 412                           const struct media_request_object_ops *ops,
 413                           void *priv)
 414 {
 415         return NULL;
 416 }
 417
 418 static inline void media_request_object_init(struct media_request_object *obj)
 419 {
 420         obj->ops = NULL;
 421         obj->req = NULL;
 422 }
 423
 424 static inline int media_request_object_bind(struct media_request *req,
 425                                const struct media_request_object_ops *ops,
 426                                void *priv, bool is_buffer,
 427                                struct media_request_object *obj)
 428 {
 429         return 0;
 430 }
 431
 432 static inline void media_request_object_unbind(struct media_request_object *obj)
 433 {
 434 }
 435
 436 static inline void media_request_object_complete(struct media_request_object *obj)
 437 {
 438 }
 439
 440 #endif
 441
 442 #endif