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"
34 #define HAL_LIBRARY_PATH3 "/odm/lib64/hw"
36 #define HAL_LIBRARY_PATH1 "/system/lib/hw"
37 #define HAL_LIBRARY_PATH2 "/vendor/lib/hw"
38 #define HAL_LIBRARY_PATH3 "/odm/lib/hw"
42 * There are a set of variant filename for modules. The form of the filename
43 * is "<MODULE_ID>.variant.so" so for the led module the Dream variants
44 * of base "ro.product.board", "ro.board.platform" and "ro.arch" would be:
52 static const char *variant_keys[] = {
53 "ro.hardware", /* This goes first so that it can pick up a different
54 file on the emulator. */
60 static const int HAL_VARIANT_KEYS_COUNT =
61 (sizeof(variant_keys)/sizeof(variant_keys[0]));
64 * Load the file defined by the variant and if successful
65 * return the dlopen handle and the hmi.
66 * @return 0 = success, !0 = failure.
68 static int load(const char *id,
70 const struct hw_module_t **pHmi)
74 struct hw_module_t *hmi = NULL;
77 * load the symbols resolving undefined symbols before
78 * dlopen returns. Since RTLD_GLOBAL is not or'd in with
79 * RTLD_NOW the external symbols will not be global
81 handle = dlopen(path, RTLD_NOW);
83 char const *err_str = dlerror();
84 ALOGE("load: module=%s\n%s", path, err_str?err_str:"unknown");
89 /* Get the address of the struct hal_module_info. */
90 const char *sym = HAL_MODULE_INFO_SYM_AS_STR;
91 hmi = (struct hw_module_t *)dlsym(handle, sym);
93 ALOGE("load: couldn't find symbol %s", sym);
98 /* Check that the id matches */
99 if (strcmp(id, hmi->id) != 0) {
100 ALOGE("load: id=%s != hmi->id=%s", id, hmi->id);
113 if (handle != NULL) {
118 ALOGV("loaded HAL id=%s path=%s hmi=%p handle=%p",
119 id, path, *pHmi, handle);
128 * Check if a HAL with given name and subname exists, if so return 0, otherwise
129 * otherwise return negative. On success path will contain the path to the HAL.
131 static int hw_module_exists(char *path, size_t path_len, const char *name,
134 snprintf(path, path_len, "%s/%s.%s.so",
135 HAL_LIBRARY_PATH3, name, subname);
136 if (access(path, R_OK) == 0)
139 snprintf(path, path_len, "%s/%s.%s.so",
140 HAL_LIBRARY_PATH2, name, subname);
141 if (access(path, R_OK) == 0)
144 snprintf(path, path_len, "%s/%s.%s.so",
145 HAL_LIBRARY_PATH1, name, subname);
146 if (access(path, R_OK) == 0)
152 int hw_get_module_by_class(const char *class_id, const char *inst,
153 const struct hw_module_t **module)
156 char prop[PATH_MAX] = {0};
157 char path[PATH_MAX] = {0};
158 char name[PATH_MAX] = {0};
159 char prop_name[PATH_MAX] = {0};
163 snprintf(name, PATH_MAX, "%s.%s", class_id, inst);
165 strlcpy(name, class_id, PATH_MAX);
168 * Here we rely on the fact that calling dlopen multiple times on
169 * the same .so will simply increment a refcount (and not load
170 * a new copy of the library).
171 * We also assume that dlopen() is thread-safe.
174 /* First try a property specific to the class and possibly instance */
175 snprintf(prop_name, sizeof(prop_name), "ro.hardware.%s", name);
176 if (property_get(prop_name, prop, NULL) > 0) {
177 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
182 /* Loop through the configuration variants looking for a module */
183 for (i=0 ; i<HAL_VARIANT_KEYS_COUNT; i++) {
184 if (property_get(variant_keys[i], prop, NULL) == 0) {
187 if (hw_module_exists(path, sizeof(path), name, prop) == 0) {
192 /* Nothing found, try the default */
193 if (hw_module_exists(path, sizeof(path), name, "default") == 0) {
200 /* load the module, if this fails, we're doomed, and we should not try
201 * to load a different variant. */
202 return load(class_id, path, module);
205 int hw_get_module(const char *id, const struct hw_module_t **module)
207 return hw_get_module_by_class(id, NULL, module);