1 /*
2  * Copyright (C) 2014 Red Hat
3  * Author: Rob Clark <robdclark@gmail.com>
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining a
6  * copy of this software and associated documentation files (the "Software"),
7  * to deal in the Software without restriction, including without limitation
8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9  * and/or sell copies of the Software, and to permit persons to whom the
10  * Software is furnished to do so, subject to the following conditions:
11  *
12  * The above copyright notice and this permission notice shall be included in
13  * all copies or substantial portions of the Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
19  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
20  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
21  * OTHER DEALINGS IN THE SOFTWARE.
22  */
23 
24 #ifndef DRM_MODESET_LOCK_H_
25 #define DRM_MODESET_LOCK_H_
26 
27 #include <linux/ww_mutex.h>
28 
29 struct drm_modeset_lock;
30 
31 /**
32  * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
33  * @ww_ctx: base acquire ctx
34  * @contended: used internally for -EDEADLK handling
35  * @locked: list of held locks
36  * @trylock_only: trylock mode used in atomic contexts/panic notifiers
37  *
38  * Each thread competing for a set of locks must use one acquire
39  * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
40  * retry.
41  */
42 struct drm_modeset_acquire_ctx {
43 
44 	struct ww_acquire_ctx ww_ctx;
45 
46 	/**
47 	 * Contended lock: if a lock is contended you should only call
48 	 * drm_modeset_backoff() which drops locks and slow-locks the
49 	 * contended lock.
50 	 */
51 	struct drm_modeset_lock *contended;
52 
53 	/**
54 	 * list of held locks (drm_modeset_lock)
55 	 */
56 	struct list_head locked;
57 
58 	/**
59 	 * Trylock mode, use only for panic handlers!
60 	 */
61 	bool trylock_only;
62 };
63 
64 /**
65  * struct drm_modeset_lock - used for locking modeset resources.
66  * @mutex: resource locking
67  * @head: used to hold it's place on state->locked list when
68  *    part of an atomic update
69  *
70  * Used for locking CRTCs and other modeset resources.
71  */
72 struct drm_modeset_lock {
73 	/**
74 	 * modeset lock
75 	 */
76 	struct ww_mutex mutex;
77 
78 	/**
79 	 * Resources that are locked as part of an atomic update are added
80 	 * to a list (so we know what to unlock at the end).
81 	 */
82 	struct list_head head;
83 };
84 
85 extern struct ww_class crtc_ww_class;
86 
87 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
88 		uint32_t flags);
89 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
90 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
91 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
92 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
93 
94 /**
95  * drm_modeset_lock_init - initialize lock
96  * @lock: lock to init
97  */
98 static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
99 {
100 	ww_mutex_init(&lock->mutex, &crtc_ww_class);
101 	INIT_LIST_HEAD(&lock->head);
102 }
103 
104 /**
105  * drm_modeset_lock_fini - cleanup lock
106  * @lock: lock to cleanup
107  */
108 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
109 {
110 	WARN_ON(!list_empty(&lock->head));
111 }
112 
113 /**
114  * drm_modeset_is_locked - equivalent to mutex_is_locked()
115  * @lock: lock to check
116  */
117 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
118 {
119 	return ww_mutex_is_locked(&lock->mutex);
120 }
121 
122 int drm_modeset_lock(struct drm_modeset_lock *lock,
123 		struct drm_modeset_acquire_ctx *ctx);
124 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
125 		struct drm_modeset_acquire_ctx *ctx);
126 void drm_modeset_unlock(struct drm_modeset_lock *lock);
127 
128 struct drm_device;
129 struct drm_crtc;
130 struct drm_plane;
131 
132 void drm_modeset_lock_all(struct drm_device *dev);
133 void drm_modeset_unlock_all(struct drm_device *dev);
134 void drm_modeset_lock_crtc(struct drm_crtc *crtc,
135 			   struct drm_plane *plane);
136 void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
137 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
138 struct drm_modeset_acquire_ctx *
139 drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
140 
141 int drm_modeset_lock_all_crtcs(struct drm_device *dev,
142 		struct drm_modeset_acquire_ctx *ctx);
143 
144 #endif /* DRM_MODESET_LOCK_H_ */
145