genlock.h revision 513ddc2124abf90c63af41999201f0d2031af0c8 
1/*
2 * Copyright (c) 2011-2012, The Linux Foundation. All rights reserved.
3
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *   * Redistributions of source code must retain the above copyright
8 *     notice, this list of conditions and the following disclaimer.
9 *   * Redistributions in binary form must reproduce the above
10 *     copyright notice, this list of conditions and the following
11 *     disclaimer in the documentation and/or other materials provided
12 *     with the distribution.
13 *   * Neither the name of The Linux Foundation nor the names of its
14 *     contributors may be used to endorse or promote products derived
15 *     from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
21 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
26 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
27 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#ifndef INCLUDE_LIBGENLOCK
31#define INCLUDE_LIBGENLOCK
32
33#include <cutils/native_handle.h>
34
35#ifdef __cplusplus
36extern "C" {
37#endif
38
39    /* Genlock lock types */
40    typedef enum genlock_lock_type{
41        GENLOCK_READ_LOCK  = 1<<0,  // Read lock
42        GENLOCK_WRITE_LOCK = 1<<1,  // Write lock
43    }genlock_lock_type_t;
44
45    /* Genlock return values */
46    typedef enum genlock_status{
47        GENLOCK_NO_ERROR = 0,
48        GENLOCK_TIMEDOUT,
49        GENLOCK_FAILURE,
50    } genlock_status_t;
51
52    /* Genlock defines */
53#define GENLOCK_MAX_TIMEOUT 1000 // Max 1s timeout
54
55    /*
56     * Create a genlock lock. The genlock lock file descriptor and the lock
57     * handle are stored in the buffer_handle.
58     *
59     * @param: handle of the buffer
60     * @return error status.
61     */
62    genlock_status_t genlock_create_lock(native_handle_t *buffer_handle);
63
64
65    /*
66     * Release a genlock lock associated with the handle.
67     *
68     * @param: handle of the buffer
69     * @return error status.
70     */
71    genlock_status_t genlock_release_lock(native_handle_t *buffer_handle);
72
73    /*
74     * Attach a lock to the buffer handle passed via an IPC.
75     *
76     * @param: handle of the buffer
77     * @return error status.
78     */
79    genlock_status_t genlock_attach_lock(native_handle_t *buffer_handle);
80
81    /*
82     * Lock the buffer specified by the buffer handle. The lock held by the
83     * buffer is specified by the lockType. This function will block if a write
84     * lock is requested on the buffer which has previously been locked for a
85     * read or write operation. A buffer can be locked by multiple clients for
86     * read. An optional timeout value can be specified.
87     * By default, there is no timeout.
88     *
89     * @param: handle of the buffer
90     * @param: type of lock to be acquired by the buffer.
91     * @param: timeout value in ms. GENLOCK_MAX_TIMEOUT is the maximum timeout
92     *         value.
93     * @return error status.
94     */
95    genlock_status_t genlock_lock_buffer(native_handle_t *buffer_handle,
96                                         genlock_lock_type_t lockType,
97                                         int timeout);
98
99    /*
100     * Unlocks a buffer that has previously been locked by the client.
101     *
102     * @param: handle of the buffer to be unlocked.
103     * @return: error status.
104     */
105    genlock_status_t genlock_unlock_buffer(native_handle_t *buffer_handle);
106
107    /*
108     * Blocks the calling process until the lock held on the handle is unlocked.
109     *
110     * @param: handle of the buffer
111     * @param: timeout value for the wait.
112     * return: error status.
113     */
114    genlock_status_t genlock_wait(native_handle_t *buffer_handle, int timeout);
115
116    /*
117     * Convert a write lock that we own to a read lock
118     *
119     * @param: handle of the buffer
120     * @param: timeout value for the wait.
121     * return: error status.
122     */
123    genlock_status_t genlock_write_to_read(native_handle_t *buffer_handle,
124                                           int timeout);
125
126#ifdef __cplusplus
127}
128#endif
129#endif
130