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 */
32 #define HAL_LIBRARY_PATH1 "/system/lib64/hw"
33 #define HAL_LIBRARY_PATH2 "/vendor/lib64/hw"
35 #define HAL_LIBRARY_PATH1 "/system/lib/hw"
36 #define HAL_LIBRARY_PATH2 "/vendor/lib/hw"
40 * There are a set of variant filename for modules. The form of the filename
41 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
42 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
50 static const char *variant_keys[] = {
51 "ro.hardware", /* This goes first so that it can pick up a different
52 file on the emulator. */
58 static const int HAL_VARIANT_KEYS_COUNT =
59 (sizeof(variant_keys)/sizeof(variant_keys[0]));
62 * Load the file defined by the variant and if successful
63 * return the dlopen handle and the hmi.
64 * @return 0 = success, !0 = failure.
66 static int load(const char *id,
68 const struct hw_module_t **pHmi)
72 struct hw_module_t *hmi = NULL;
75 * load the symbols resolving undefined symbols before
76 * dlopen returns. Since RTLD_GLOBAL is not or'd in with
77 * RTLD_NOW the external symbols will not be global
79 handle = dlopen(path, RTLD_NOW);
81 char const *err_str = dlerror();
82 ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown");
87 /* Get the address of the struct hal_module_info. */
88 const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
89 hmi = (struct hw_module_t *)dlsym(handle, sym);
91 ALOGE("load: couldn't find symbol %s", sym);
96 /* Check that the id matches */
97 if (strcmp(id, hmi->id) != 0) {
98 ALOGE("load: id=%s != hmi->id=%s", id, hmi->id);
111 if (handle != NULL) {
116 ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
117 id, path, *pHmi, handle);
126 * Check if a HAL with given name and subname exists, if so return 0, otherwise
127 * otherwise return negative. On success path will contain the path to the HAL.
129 static int hw_module_exists(char *path, size_t path_len, const char *name,
132 snprintf(path, path_len, "%s/%s.%s.so",
133 HAL_LIBRARY_PATH2, name, subname);
134 if (access(path, R_OK) == 0)
137 snprintf(path, path_len, "%s/%s.%s.so",
138 HAL_LIBRARY_PATH1, name, subname);
139 if (access(path, R_OK) == 0)
145 int hw_get_module_by_class(const char *class_id, const char *inst,
146 const struct hw_module_t **module)
149 char prop[PATH_MAX] = {0};
150 char path[PATH_MAX] = {0};
151 char name[PATH_MAX] = {0};
152 char prop_name[PATH_MAX] = {0};
156 snprintf(name, PATH_MAX, "%s.%s", class_id, inst);
158 strlcpy(name, class_id, PATH_MAX);
161 * Here we rely on the fact that calling dlopen multiple times on
162 * the same .so will simply increment a refcount (and not load
163 * a new copy of the library).
164 * We also assume that dlopen() is thread-safe.
167 /* First try a property specific to the class and possibly instance */
168 snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name);
169 if (property_get(prop_name, prop, NULL) > 0) {
170 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
175 /* Loop through the configuration variants looking for a module */
176 for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) {
177 if (property_get(variant_keys[i], prop, NULL) == 0) {
180 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
185 /* Nothing found, try the default */
186 if (hw_module_exists(path, sizeof(path), name, "default") == 0) {
193 /* load the module, if this fails, we're doomed, and we should not try
194 * to load a different variant. */
195 return load(class_id, path, module);
198 int hw_get_module(const char *id, const struct hw_module_t **module)
200 return hw_get_module_by_class(id, NULL, module);