1 /*
2 * drm_sync_helper.h: software fence and helper functions for fences and
3 * reservations used for dma buffer access synchronization between drivers.
4 *
5 * Copyright 2014 Google, Inc.
6 *
7 * This software is licensed under the terms of the GNU General Public
8 * License version 2, as published by the Free Software Foundation, and
9 * may be copied, distributed, and modified under those terms.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 */
16
17 #ifndef _DRM_SYNC_HELPER_H_
18 #define _DRM_SYNC_HELPER_H_
19
20 #include <linux/fence.h>
21 #include <linux/reservation.h>
22 #include <linux/atomic.h>
23 #include <linux/workqueue.h>
24
25 /**
26 * Create software fence
27 * @context: execution context
28 * @seqno: the sequence number of this fence inside the execution context
29 */
30 struct fence *drm_sw_fence_new(unsigned int context,
31 unsigned seqno);
32
33 /**
34 * Signal and decrease reference count for a fence if it exists
35 * @fence: fence to signal
36 *
37 * Utility function called when owner access to object associated with fence is
38 * finished (e.g. GPU done with rendering).
39 */
drm_fence_signal_and_put(struct fence **fence)40 static inline void drm_fence_signal_and_put(struct fence **fence)
41 {
42 if (*fence) {
43 fence_signal(*fence);
44 fence_put(*fence);
45 *fence = NULL;
46 }
47 }
48
49 struct drm_reservation_cb;
50
51 struct drm_reservation_fence_cb {
52 struct fence_cb base;
53 struct drm_reservation_cb *parent;
54 struct fence *fence;
55 };
56
57 /**
58 * Callback executed when all fences in reservation callback are signaled
59 * @rcb: reservation callback structure
60 * @context: context provided by user at init time
61 */
62 typedef void (*drm_reservation_cb_func_t)(struct drm_reservation_cb *rcb,
63 void *context);
64
65 /**
66 * Reservation callback structure
67 * @work: work context in which func is executed
68 * @fence_cbs: fence callbacks array
69 * @num_fence_cbs: number of fence callbacks
70 * @count: count of signaled fences, when it drops to 0 func is called
71 * @func: callback to execute when all fences are signaled
72 * @context: context provided by user during initialization
73 *
74 * It is safe and expected that func will destroy this structure before
75 * returning.
76 */
77 struct drm_reservation_cb {
78 struct work_struct work;
79 struct drm_reservation_fence_cb **fence_cbs;
80 unsigned num_fence_cbs;
81 atomic_t count;
82 void *context;
83 drm_reservation_cb_func_t func;
84 };
85
86 /**
87 * Initialize reservation callback
88 * @rcb: reservation callback structure to initialize
89 * @func: function to call when all fences are signaled
90 * @context: parameter to call func with
91 */
92 void drm_reservation_cb_init(struct drm_reservation_cb *rcb,
93 drm_reservation_cb_func_t func,
94 void *context);
95
96 /**
97 * Add fences from reservation object to callback
98 * @rcb: reservation callback structure
99 * @resv: reservation object
100 * @exclusive: (for exclusive wait) when true add all fences, otherwise only
101 * exclusive fence
102 */
103 int drm_reservation_cb_add(struct drm_reservation_cb *rcb,
104 struct reservation_object *resv,
105 bool exclusive);
106
107 /**
108 * Finish adding fences
109 * @rcb: reservation callback structure
110 *
111 * It will trigger callback worker if all fences were signaled before.
112 */
113 void drm_reservation_cb_done(struct drm_reservation_cb *rcb);
114
115 /**
116 * Cleanup reservation callback structure
117 * @rcb: reservation callback structure
118 *
119 * Can be called to cancel primed reservation callback.
120 */
121 void drm_reservation_cb_fini(struct drm_reservation_cb *rcb);
122
123 /**
124 * Add reservation to array of reservations
125 * @resv: reservation to add
126 * @resvs: array of reservations
127 * @excl_resvs_bitmap: bitmap for exclusive reservations
128 * @num_resvs: number of reservations in array
129 * @exclusive: bool to store in excl_resvs_bitmap
130 */
131 void
132 drm_add_reservation(struct reservation_object *resv,
133 struct reservation_object **resvs,
134 unsigned long *excl_resvs_bitmap,
135 unsigned int *num_resvs, bool exclusive);
136
137 /**
138 * Acquire ww_mutex lock on all reservations in the array
139 * @resvs: array of reservations
140 * @num_resvs: number of reservations in the array
141 * @ctx: ww mutex context
142 */
143 int drm_lock_reservations(struct reservation_object **resvs,
144 unsigned int num_resvs, struct ww_acquire_ctx *ctx);
145
146 /**
147 * Release ww_mutex lock on all reservations in the array
148 * @resvs: array of reservations
149 * @num_resvs: number of reservations in the array
150 * @ctx: ww mutex context
151 */
152 void drm_unlock_reservations(struct reservation_object **resvs,
153 unsigned int num_resvs,
154 struct ww_acquire_ctx *ctx);
155
156 #endif
157