开源自己编写的HAL层代码在，hardware/libhardware 目录下面，具体步奏
用系统自己的实例代码fingerprint例子
- 首先在hardware/libhardware/include/hardware目录下创建fingerprint.h文件
#ifndef ANDROID_INCLUDE_HARDWARE_FINGERPRINT_H
#define ANDROID_INCLUDE_HARDWARE_FINGERPRINT_H
#include <hardware/hardware.h>
#include <hardware/hw_auth_token.h>
HAL版本号
#define FINGERPRINT_MODULE_API_VERSION_1_0 HARDWARE_MODULE_API_VERSION(1, 0)
HAL模块名
#define FINGERPRINT_HARDWARE_MODULE_ID "fingerprint"
#定义的具体方法
typedef struct fingerprint_device {
/**
必须 写死不能省略
* Common methods of the fingerprint device. This *must* be the first member
* of fingerprint_device as users of this structure will cast a hw_device_t
* to fingerprint_device pointer in contexts where it's known
* the hw_device_t references a fingerprint_device.
*/
struct hw_device_t common;
fingerprint_notify_t notify;
第一个参数必须是device结构体，在device中定义的方法
int (*set_notify)(struct fingerprint_device *dev, fingerprint_notify_t notify);
uint64_t (*pre_enroll)(struct fingerprint_device *dev);
} fingerprint_device_t;
# 必须模块
typedef struct fingerprint_module {
/**
写死不能省略
* Common methods of the fingerprint module. This *must* be the first member
* of fingerprint_module as users of this structure will cast a hw_module_t
* to fingerprint_module pointer in contexts where it's known
* the hw_module_t references a fingerprint_module.
*/
struct hw_module_t common;
} fingerprint_module_t;
#endif /* ANDROID_INCLUDE_HARDWARE_FINGERPRINT_H */
- 接着在hardware/libhardware/modules/目录下创建一个fingerprint的文件夹，里面包含一个fingerprint.c和Android.bp，看原生fingerprint.c文件
#define LOG_TAG "FingerprintHal"
#include <errno.h>
#include <malloc.h>
#include <stdint.h>
#include <string.h>
#include <log/log.h>
引入在hardware/libhardware/include/hardware下创建的fingerprint.h文件
#include <hardware/fingerprint.h>
#include <hardware/hardware.h>
#关闭设备
static int fingerprint_close(hw_device_t *dev)
{
if (dev) {
free(dev);
return 0;
} else {
return -1;
}
}
set_notify 的具体实现类
static int set_notify_callback(struct fingerprint_device *dev,
fingerprint_notify_t notify) {
/* Decorate with locks */
dev->notify = notify;
return FINGERPRINT_ERROR;
}
#打开设备
static int fingerprint_open(const hw_module_t* module, const char __unused *id,
hw_device_t** device)
{
if (device == NULL) {
ALOGE("NULL device on open");
return -EINVAL;
}
fingerprint_device_t *dev = malloc(sizeof(fingerprint_device_t));
memset(dev, 0, sizeof(fingerprint_device_t));
dev->common.tag = HARDWARE_DEVICE_TAG;
dev->common.version = FINGERPRINT_MODULE_API_VERSION_2_0;
dev->common.module = (struct hw_module_t*) module;
dev->common.close = fingerprint_close;
dev->pre_enroll = fingerprint_pre_enroll;
dev->enroll = fingerprint_enroll;
dev->get_authenticator_id = fingerprint_get_auth_id;
dev->cancel = fingerprint_cancel;
dev->remove = fingerprint_remove;
dev->set_active_group = fingerprint_set_active_group;
dev->authenticate = fingerprint_authenticate;
映射的具体实现方法
dev->set_notify = set_notify_callback;
dev->notify = NULL;
*device = (hw_device_t*) dev;
return 0;
}
static struct hw_module_methods_t fingerprint_module_methods = {
.open = fingerprint_open,
};
导出符号HAL_MODULE_INFO_SYM，指向自定义模块
fingerprint_module_t HAL_MODULE_INFO_SYM = {
.common = {
.tag= HARDWARE_MODULE_TAG,
.module_api_version = FINGERPRINT_MODULE_API_VERSION_2_0,
.hal_api_version = HARDWARE_HAL_API_VERSION,
// 暴露给外部调用获取对象的 TAG 类似于 hw_get_module(FINGERPRINT_HARDWARE_MODULE_ID,(hw_module_t const**)&module); 给外部调用 类似于
.id = FINGERPRINT_HARDWARE_MODULE_ID,
.name = "Demo Fingerprint HAL",
.author = "The Android Open Source Project",
.methods = &fingerprint_module_methods,
},
};
- Android.bp文件
cc_library_shared {
这个就是编译出来的so库的名字
name: "fingerprint.default",
relative_install_path: "hw",
proprietary: true,
srcs: ["fingerprint.c"],
cflags: ["-Wall", "-Werror"],
header_libs: ["libhardware_headers"],
shared_libs: ["liblog"],
}
-
在Andorid根目录下编译初始化编译环境
source build/envsetup.sh
lunch xx
执行编译
mmm hardware/libhardware/modules/fingerprint/编译成功以后就会在out目录下生成共享fingerprint.default.so库，这个库就是可以在HIDL层或者JNI层直接调用了
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