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
 29struct 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 */
 42struct 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 */
 72struct 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
 85extern struct ww_class crtc_ww_class;
 86
 87void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
 88		uint32_t flags);
 89void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
 90void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
 91void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
 92int 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 */
 98static 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 */
108static 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 */
117static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
118{
119	return ww_mutex_is_locked(&lock->mutex);
120}
121
122int drm_modeset_lock(struct drm_modeset_lock *lock,
123		struct drm_modeset_acquire_ctx *ctx);
124int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
125		struct drm_modeset_acquire_ctx *ctx);
126void drm_modeset_unlock(struct drm_modeset_lock *lock);
127
128struct drm_device;
129struct drm_crtc;
130struct drm_plane;
131
132void drm_modeset_lock_all(struct drm_device *dev);
133void drm_modeset_unlock_all(struct drm_device *dev);
134void drm_modeset_lock_crtc(struct drm_crtc *crtc,
135			   struct drm_plane *plane);
136void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
137void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
138struct drm_modeset_acquire_ctx *
139drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
140
141int drm_modeset_lock_all_ctx(struct drm_device *dev,
142			     struct drm_modeset_acquire_ctx *ctx);
143
144#endif /* DRM_MODESET_LOCK_H_ */