src/gbm/main/backend.c

   1 /*
   2  * Copyright © 2011 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  19  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  20  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22  * DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Benjamin Franzke <benjaminfranzke@googlemail.com>
  26  */
  27
  28 #include <stdio.h>
  29 #include <stddef.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <limits.h>
  33
  34 #include "backend.h"
  35
  36 #define ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))
  37
  38 extern const struct gbm_backend gbm_dri_backend;
  39
  40 struct backend_desc {
  41    const char *name;
  42    const struct gbm_backend *builtin;
  43 };
  44
  45 static const struct backend_desc backends[] = {
  46    { "gbm_dri.so", &gbm_dri_backend },
  47 };
  48
  49 static const void *
  50 load_backend(const struct backend_desc *backend)
  51 {
  52    const void *init = NULL;
  53
  54    if (backend == NULL)
  55       return NULL;
  56
  57    if (backend->builtin) {
  58       init = backend->builtin;
  59    }
  60
  61    return init;
  62 }
  63
  64 static const struct backend_desc *
  65 find_backend(const char *name)
  66 {
  67    const struct backend_desc *backend = NULL;
  68    unsigned i;
  69
  70    for (i = 0; i < ARRAY_SIZE(backends); ++i) {
  71       if (strcmp(backends[i].name, name) == 0) {
  72          backend = &backends[i];
  73          break;
  74       }
  75    }
  76
  77    return backend;
  78 }
  79
  80 struct gbm_device *
  81 _gbm_create_device(int fd)
  82 {
  83    const struct gbm_backend *backend = NULL;
  84    struct gbm_device *dev = NULL;
  85    unsigned i;
  86    const char *b;
  87
  88    b = getenv("GBM_BACKEND");
  89    if (b)
  90       backend = load_backend(find_backend(b));
  91
  92    if (backend)
  93       dev = backend->create_device(fd);
  94
  95    for (i = 0; i < ARRAY_SIZE(backends) && dev == NULL; ++i) {
  96       backend = load_backend(&backends[i]);
  97       if (backend == NULL)
  98          continue;
  99
 100       dev = backend->create_device(fd);
 101    }
 102
 103    return dev;
 104 }