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
media_request_lock_for_access(struct media_request * req)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  */
media_request_unlock_for_access(struct media_request * req)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
media_request_lock_for_update(struct media_request * req)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  */
media_request_unlock_for_update(struct media_request * req)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  */
media_request_get(struct media_request * req)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 -EBADR 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 
media_request_get(struct media_request * req)223 static inline void media_request_get(struct media_request *req)
224 {
225 }
226 
media_request_put(struct media_request * req)227 static inline void media_request_put(struct media_request *req)
228 {
229 }
230 
231 static inline struct media_request *
media_request_get_by_fd(struct media_device * mdev,int request_fd)232 media_request_get_by_fd(struct media_device *mdev, int request_fd)
233 {
234 	return ERR_PTR(-EBADR);
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  */
media_request_object_get(struct media_request_object * obj)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
media_request_lock_for_access(struct media_request * req)383 media_request_lock_for_access(struct media_request *req)
384 {
385 	return -EINVAL;
386 }
387 
media_request_unlock_for_access(struct media_request * req)388 static inline void media_request_unlock_for_access(struct media_request *req)
389 {
390 }
391 
392 static inline int __must_check
media_request_lock_for_update(struct media_request * req)393 media_request_lock_for_update(struct media_request *req)
394 {
395 	return -EINVAL;
396 }
397 
media_request_unlock_for_update(struct media_request * req)398 static inline void media_request_unlock_for_update(struct media_request *req)
399 {
400 }
401 
media_request_object_get(struct media_request_object * obj)402 static inline void media_request_object_get(struct media_request_object *obj)
403 {
404 }
405 
media_request_object_put(struct media_request_object * obj)406 static inline void media_request_object_put(struct media_request_object *obj)
407 {
408 }
409 
410 static inline struct media_request_object *
media_request_object_find(struct media_request * req,const struct media_request_object_ops * ops,void * priv)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 
media_request_object_init(struct media_request_object * obj)418 static inline void media_request_object_init(struct media_request_object *obj)
419 {
420 	obj->ops = NULL;
421 	obj->req = NULL;
422 }
423 
media_request_object_bind(struct media_request * req,const struct media_request_object_ops * ops,void * priv,bool is_buffer,struct media_request_object * obj)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 
media_request_object_unbind(struct media_request_object * obj)432 static inline void media_request_object_unbind(struct media_request_object *obj)
433 {
434 }
435 
media_request_object_complete(struct media_request_object * obj)436 static inline void media_request_object_complete(struct media_request_object *obj)
437 {
438 }
439 
440 #endif
441 
442 #endif
443