2 * Copyright (C) 2008 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <hardware/hardware.h>
19 #include <cutils/properties.h>
28 #include <utils/Log.h>
30 /** Base path of the hal modules */
31 #define HAL_LIBRARY_PATH "/system/lib/hw"
34 * There are a set of variant filename for modules. The form of the filename
35 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
36 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
44 #define HAL_DEFAULT_VARIANT "default"
45 #define HAL_VARIANT_KEYS_COUNT 4
46 static const char *variant_keys[HAL_VARIANT_KEYS_COUNT] = {
54 * Load the file defined by the path and if succesfull
55 * return the dlopen handle and the hmi.
56 * @return 0 = success, !0 = failure.
58 static int load(const char *id,
61 const struct hw_module_t **pHmi)
65 const struct hw_module_t *hmi;
67 LOGV("load: E id=%s path=%s", id, path);
70 * load the symbols resolving undefined symbols before
71 * dlopen returns. Since RTLD_GLOBAL is not or'd in with
72 * RTLD_NOW the external symbols will not be global
74 handle = dlopen(path, RTLD_NOW);
76 char const *err_str = dlerror();
77 LOGW("load: module=%s error=%s", path, err_str);
82 /* Get the address of the struct hal_module_info. */
83 const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
84 hmi = (const struct hw_module_t *)dlsym(handle, sym);
86 char const *err_str = dlerror();
87 LOGE("load: couldn't find symbol %s", sym);
92 /* Check that the id matches */
93 if (strcmp(id, hmi->id) != 0) {
94 LOGE("load: id=%s != hmi->id=%s", id, hmi->id);
105 if (handle != NULL) {
114 LOGV("load: X id=%s path=%s hmi=%p pHandle=%p status=%d",
115 id, path, *pHmi, *pHandle, status);
119 int hw_get_module(const char *id, const struct hw_module_t **module)
122 const struct hw_module_t *hmi = NULL;
124 char variant[PATH_MAX];
129 * Here we rely on the fact that calling dlopen multiple times on
130 * the same .so will simply increment a refcount (and not load
131 * a new copy of the library).
132 * We also assume that dlopen() is thread-safe.
135 LOGV("hal_module_info_get: Load module id=%s", id);
137 /* Loop through the configuration variants looking for a module */
139 for (i = 0; (status != 0) && (i < HAL_VARIANT_KEYS_COUNT); i++) {
141 /* Get variant or default */
142 if (strcmp(variant_keys[i], HAL_DEFAULT_VARIANT) == 0) {
143 strncpy(variant, HAL_DEFAULT_VARIANT, sizeof(variant)-1);
144 variant[sizeof(variant)-1] = 0;
146 if (property_get(variant_keys[i], variant, NULL) == 0) {
151 /* Construct the path then try to load */
152 snprintf(path, sizeof(path), "%s/%s.%s.so",
153 HAL_LIBRARY_PATH, id, variant);
154 status = load(id, path, &handle, &hmi);
158 if (handle != NULL) {
164 LOGV("hal_module_info_get: X id=%s hmi=%p status=%d", id, hmi, status);