Android 8.0 添加HIDL

1.编写hal文件并编译

在hardware/interfaces/目录下创建test文件夹和基版本1.0，这个版本号分为两部分，major.minor。major版本不变得话，只能添加api，不能修改。

创建ITest.hal和types.hal
hardware/interfaces/test/1.0/ITest.hal

package android.hardware.test@1.0;interface ITest
{//get led status get() generates (LedStatus result);//set led status set(LedStatus  val) generates(int32_t  ret);getBrightnessRange() generates(bool ret,BrightnessRange range);setBrightnessValue(vec<int32_t> range) generates(bool ret);on() ;off() ;};

hardware/interfaces/test/1.0/types.hal

package android.hardware.test@1.0;enum LedStatus : uint32_t {LED_ON,LED_OFF,LED_BAD_VALUE,
};struct BrightnessRange {uint32_t min;uint32_t max;
};

添加完后，设置环境变量之后，执行./hardware/interfaces/update-makefiles.sh 会自动生成编译编译脚本，然后在

hardware/interfaces/test/1.0/ 路径下执行mm，会生成所需要得hidl库，接下来我们需要实现hidl interface，供client调用。

2. 实现Hidl Interface

首先实现ITest interface的子类testImpl 得头文件和对应得cpp。

hardware/interfaces/test/1.0/default/testImpl.h

#ifndef ANDROID_HARDWARE_LED_V1_0_LED_H
#define ANDROID_HARDWARE_LED_V1_0_LED_H
#include <android/hardware/test/1.0/ITest.h>#include <hidl/Status.h>#include <hidl/MQDescriptor.h>namespace android {
namespace hardware {
namespace test {
namespace V1_0 {
namespace implementation {using ::android::hardware::test::V1_0::LedStatus;
using ::android::hardware::test::V1_0::BrightnessRange;
using ::android::hardware::test::V1_0::ITest;
using ::android::hardware::hidl_array;
using ::android::hardware::hidl_string;
using ::android::hardware::hidl_vec;
using ::android::hardware::Return;
using ::android::hardware::Void;
using ::android::sp;struct testImpl : public ITest {public:testImpl();Return<LedStatus>  get() override ;Return<int32_t> set(LedStatus val) override;Return<void> on() override;Return<void> off() override;Return<void> getBrightnessRange(getBrightnessRange_cb _hidl_cb) override;Return<bool> setBrightnessValue(const hidl_vec<int32_t>& range) override;private:LedStatus state;
};extern "C" ITest* HIDL_FETCH_ITest(const char* name);
}  // namespace implementation
}  // namespace V1_0
}  // namespace test
}  // namespace hardware
}  // namespace android#endif //ANDROID_HARDWARE_LED_V1_0_LED_H

testImpl.cpp

#define LOG_TAG "TestService"#include <log/log.h>
#include "testImpl.h"namespace android {
namespace hardware {
namespace test {
namespace V1_0 {
namespace implementation {testImpl::testImpl() {state = LedStatus::LED_BAD_VALUE;ALOGE("testImpl Init status:%d", state);
}Return<void> testImpl::on() {state = LedStatus::LED_ON;ALOGE("testImpl on status:%d", state);return Void();
}Return<void> testImpl::off() {state = LedStatus::LED_OFF;ALOGE("testImpl off status:%d", state);  return Void();
}Return<LedStatus>  testImpl::get() {return state;
}
Return<int32_t> testImpl::set(LedStatus val) {if(val == LedStatus::LED_OFF || val == LedStatus::LED_ON)state = val;elsereturn -1;return 0;
}Return<void> testImpl::getBrightnessRange(getBrightnessRange_cb _hidl_cb)
{ALOGE("testImpl getBrightnessRange ");BrightnessRange range;range.max = 100;range.min = 1;_hidl_cb(true,range);return Void();}Return<bool> testImpl::setBrightnessValue(const hidl_vec<int32_t>& range)
{ALOGE("testImpl getBrightnessValue ");auto iter = range.begin();ALOGE("testImpl getBrightnessValue range.begin: %d",*iter);iter = range.end();ALOGE("testImpl getBrightnessValue range.end: %d",*iter);ALOGE("testImpl getBrightnessValue range.size: %zu",range.size());return true;
}ITest* HIDL_FETCH_ITest(const char * /*name*/) {ALOGE("testImpl HIDL_FETCH_ITest "); return new testImpl();
}}  // namespace implementation
}  // namespace V1_0
}  // namespace test
}  // namespace hardware
}  // namespace android

Android.dp

cc_library_shared {name: "android.hardware.test@1.0-impl",defaults: ["hidl_defaults"],srcs: ["testImpl.cpp"],shared_libs: ["libhidlbase","libhidltransport","libhardware","liblog","libutils","android.hardware.test@1.0",],
}cc_binary {name: "android.hardware.test@1.0-service",init_rc: ["android.hardware.test@1.0-service.rc"],srcs: ["service.cpp","testImpl.cpp"],shared_libs: ["liblog","libhardware","libhidlbase","libhidltransport","libutils","android.hardware.test@1.0",], }

3. 编写hdil service

接下来，使用相应功能填写存根并设置守护进程。可以使用passthrough方式和binder方式，示例：

hardware/interfaces/test/1.0/default/service.cpp

 #define LOG_TAG "android.hardware.test@1.0-service"#include <android/hardware/test/1.0/ITest.h>
#include <hidl/LegacySupport.h>
#include "testImpl.h"
using android::hardware::test::V1_0::ITest;
using android::hardware::test::V1_0::implementation::testImpl;
using android::hardware::defaultPassthroughServiceImplementation;
using android::hardware::configureRpcThreadpool;
using android::hardware::joinRpcThreadpool;
using android::sp;int main() {
#if 0
// Passthrough   dlopen so方式return defaultPassthroughServiceImplementation<Itest>();
#else
// Binder 方式sp<ITest> service = new testImpl();configureRpcThreadpool(1, true /*callerWillJoin*/);if(android::OK !=  service->registerAsService())return 1; joinRpcThreadpool();
#endif
}

4. 配置manifest.xml

add the code to the manifest.xm 以至于hwservicemanager 查找到指定的hidl service

About HIDL configures

system/libhidl/manifest.xml

    <hal format="hidl"><name>android.hardware.test</name><transport>hwbinder</transport>  <!--//hwbinder 或者passthrough （直通模式）-->  <version>1.0</version><interface><name>ITest</name><instance>default</instance></interface></hal>

5. hidl client端调用

hidl service运行后，可以通过C++和Java两种方式调用，非常方便，通过java直接访问，就省去了jni。

5.1 实现java调用hidl service的例子

将以下内容添加到 Android.mk 中：

 LOCAL_JAVA_LIBRARIES += android.hardware.test-V1.0-java

或将以下内容添加到 Android.bp 中：

  shared_libs: [/* … */"android.hardware.test-V1.0-java",],

该库还存在静态版：android.hardware.test-V1.0-java-static。

将以下内容添加到您的 Java 文件中：

  import android.hardware.test.V1_0.ITest;...// retry to wait until the service starts up if it is in the manifestITest server = ITest.getService(true /* retry */); // throws NoSuchElementException if not availableserver.on();

5.2 实现C++ 调用hidl service的例子

首先将 HAL 库添加到 makefile 中：

  Make：LOCAL_SHARED_LIBRARIES += android.hardware.test@1.0Soong：shared_libs: [ …, android.hardware.test@1.0 ]

接下来，添加 HAL 头文件：

  #include <android/hardware/test/1.0/ITest.h>…// in code:sp<ITest> client = ITest::getService();client->on();

下面是Demo clinet

 #define LOG_TAG "TEST_CLINET"
#include <android/hardware/test/1.0/ITest.h>
#include <log/log.h>using android::hardware::test::V1_0::ITest;
using android::hardware::test::V1_0::LedStatus;
using android::hardware::test::V1_0::BrightnessRange;
using android::hardware::hidl_vec;
using android::sp;int main(){// BrightnessRange range;sp<ITest> service = ITest::getService();if( service == nullptr ){ALOGE("Can't find ITest service...");return -1;}ALOGE("ITest ON");service->on();ALOGE("ITest OFF");service->off();ALOGE("ITest set");service->set(LedStatus::LED_ON);ALOGE("ITest get");LedStatus ret = service->get();ALOGE("ITest get: %d",ret);service->getBrightnessRange([](bool ret1,BrightnessRange range){ALOGE("ITest getBrightnessRange ret: %d",ret1);ALOGE("ITest getBrightnessRange Max: %d",range.max);ALOGE("ITest getBrightnessRange Min: %d",range.min);});int32_t array[] = {5, 6, 7};hidl_vec<int32_t> hv1 = std::vector<int32_t>(array, array + 3);bool ret2 = service->setBrightnessValue(hv1);ALOGE("ITest getBrightnessValue bool: %d",ret2);return 0;
}

参考

具体步骤

1. 创建目录cd  hardware/interfacesmkdir -p test/1.0
2. 定义hal接口Itest.halpackage android.hardware.test@1.0;interface Itest {setData(YeData data) generates (YeStatus ret);getData() generates (YeData ret);};定义数据类型types.halpackage android.hardware.test@1.0;enum YeStatus : int32_t {SUCCESS = 1,FAILED,};struct YeData {int32_t x;int32_t y;};
3. 根据.hal自动生成impl库的cpp实现make hidl-gen在hardware/interfaces/test/1.0目录执行hidl-gen命令：PACKAGE=android.hardware.test@1.0LOC= default/implhidl-gen -o $LOC -Lc++-impl -r android.hardware:hardware/interfaces $PACKAGE
4. 生成impl的Android.bphidl-gen -o default -Landroidbp-impl -r android.hardware:hardware/interfaces $PACKAGE
5. 生成hidl的Android.bp执行hardware/interfaces/update-makefiles.sh
6. 修改device/fsl/imx8q/XXX/manifest.xml添加以下代码：<hal format="hidl"><name>android.hardware.test</name><transport>hwbinder</transport><version>1.0</version><interface><name>Itest</name><instance>default</instance></interface></hal>
7. 编写.rc文件配置自启动service vendor.test-1.0 /vendor/bin/hw/android.hardware.test@1.0-serviceclass haluser systemgroup system
8. 添加PRODUCT_PACKAGES在device/fsl/imx8q/XXX/XXX.mk中新增打包.so和service到vendor.img# Yetest HALPRODUCT_PACKAGES += \android.hardware.test@1.0-impl \android.hardware.test@1.0-service
9. device/fsl/imx8q/XXX/BoardConfig.mk中指定sepolicy路径：BOARD_SEPOLICY_DIRS +=  hardware/interfaces/test/sepolicy
10. 在hardware/interfaces/test/sepolicy目录新增test.te:type test, domain;type test_exec, exec_type, vendor_file_type, file_type;hwbinder_use(test);init_daemon_domain(test)add_hwservice(test,test_hwservice)allow test hwservicemanager_prop:file {read open getattr map};allow test system_file:dir {read open getattr search};
11. hardware/interfaces/test/sepolicy目录下新增file_contexts:绑定android.hardware.test@1.0-service与test_exec的关系的关键/(vendor|system/vendor)/bin/hw/android\.hardware\.test@1\.0-service    u:object_r:test_exec:s0/(vendor|system/vendor)/lib(64)?/hw/android\.hardware\.test@1\.0-impl\.so     u:object_r:same_process_hal_file:s0
12. 新增harware/interfaces/test/sepolicy/hwservice_contexts:android.hardware.test::Itest u:object_r:test_hwservice:s0
13. 新增harware/interfaces/test/sepolicy/hwservice.te:type test_hwservice, hwservice_manager_type;