前言
学习笔记，简单介绍了 light 在 Android 8.0 上的整个调用流程
开始
一张图开场
插播下 Java Binder 服务编写框图：
C++ Binder 服务编写框图：
下面将从上到下介绍：
0.【Java 安卓LED服务类】LightsService.java
public class LightsService extends SystemService {
// 下一级 Jni 接口
static native void setLight_native(int light, int color, int mode,
int onMS, int offMS, int brightnessMode);
}
1.【JNI 客户端实现】com_android_server_lights_LightsService.cpp
static const JNINativeMethod method_table[] = {
{ "setLight_native", "(IIIIII)V", (void*)setLight_native },
};
static void setLight_native(
JNIEnv* /* env */,
jobject /* clazz */,
jint light,
jint colorARGB,
jint flashMode,
jint onMS,
jint offMS,
jint brightnessMode) {
if (!validate(light, flashMode, brightnessMode)) {
return;
}
sp<ILight> hal = LightHal::associate();
if (hal == nullptr) {
return;
}
Type type = static_cast<Type>(light);
LightState state = constructState(
colorARGB, flashMode, onMS, offMS, brightnessMode);
{
ALOGD_IF_SLOW(50, "Excessive delay setting light");
// 下一级入口
Return<Status> ret = hal->setLight(type, state);
processReturn(ret, type, state);
}
}
2.【HIDL 客户】ILight.与 HIDL 服务库通信.hal
定义了 HIDL 接口
package android.hardware.light@2.0;
interface ILight {
/**
* Set the provided lights to the provided values.
*
* @param type logical light to set
* @param state describes what the light should look like.
* @return status result of applying state transformation.
*/
setLight(Type type, LightState state) generates (Status status);
/**
* Discover what indicator lights are available.
*
* @return types list of available lights
*/
getSupportedTypes() generates (vec<Type> types);
};
3.【HIDL 客户】LightAll.cpp.调用 HIDL 服务库
::android::status_t BnHwLight::onTransact(
uint32_t _hidl_code,
const ::android::hardware::Parcel &_hidl_data,
::android::hardware::Parcel *_hidl_reply,
uint32_t _hidl_flags,
TransactCallback _hidl_cb)
// 下一级接口
Status _hidl_out_status = _hidl_mImpl->setLight(type, *state);
4.【HIDL 服务】android.hardware.light@2.0-service.启动注册 HIDL 服务库
service light-hal-2-0 /vendor/bin/hw/android.hardware.light@2.0-service
class hal
user system
group system
4.【HIDL 服务】service.cpp.向上注册 HIDL 服务库
int main() {
return defaultPassthroughServiceImplementation<ILight>();
/////////////////////////////////////////////////////////////////////////
// LegacySupport.h (system\libhidl\transport\include\hidl)
defaultPassthroughServiceImplementation(std::string name, size_t maxThreads = 1)
configureRpcThreadpool(maxThreads, true);
configureBinderRpcThreadpool(maxThreads, callerWillJoin);
ProcessState::self()->setThreadPoolConfiguration(maxThreads, callerWillJoin /*callerJoinsPool*/);
status_t result = registerPassthroughServiceImplementation<Interface>(name);
registerPassthroughServiceImplementation( std::string name = "default")
sp<Interface> service = Interface::getService(name, true /* getStub */);
status_t status = service->registerAsService(name);
joinRpcThreadpool();
joinBinderRpcThreadpool();
IPCThreadState::self()->joinThreadPool();
5.【HIDL 服务】Light.h
namespace android {
namespace hardware {
namespace light {
namespace V2_0 {
namespace implementation {
using ::android::hardware::light::V2_0::ILight;
using ::android::hardware::light::V2_0::LightState;
using ::android::hardware::light::V2_0::Status;
using ::android::hardware::light::V2_0::Type;
using ::android::hardware::Return;
using ::android::hardware::Void;
using ::android::hardware::hidl_vec;
using ::android::hardware::hidl_string;
using ::android::sp;
struct Light : public ILight {
Light(std::map<Type, light_device_t*> &&lights);
// Methods from ::android::hardware::light::V2_0::ILight follow.
Return<Status> setLight(Type type, const LightState& state) override;
Return<void> getSupportedTypes(getSupportedTypes_cb _hidl_cb) override;
private:
std::map<Type, light_device_t*> mLights;
};
extern "C" ILight* HIDL_FETCH_ILight(const char* name);
} // namespace implementation
} // namespace V2_0
} // namespace light
} // namespace hardware
} // namespace android
6.【HIDL 服务】Light.cpp.加载调用传统库
ILight* HIDL_FETCH_ILight(const char* /* name */) {
std::map<Type, light_device_t*> lights;
for(auto const &pair : kLogicalLights) {
Type type = pair.first;
const char* name = pair.second;
// 加载传统 HAL 库
light_device_t* light = getLightDevice(name);
if (light != nullptr) {
lights[type] = light;
}
}
if (lights.size() == 0) {
// Log information, but still return new Light.
// Some devices may not have any lights.
ALOGI("Could not open any lights.");
}
return new Light(std::move(lights));
}
Light::Light(std::map<Type, light_device_t*> &&lights)
: mLights(std::move(lights)) {}
// Methods from ::android::hardware::light::V2_0::ILight follow.
Return<Status> Light::setLight(Type type, const LightState& state) {
auto it = mLights.find(type);
if (it == mLights.end()) {
return Status::LIGHT_NOT_SUPPORTED;
}
light_device_t* hwLight = it->second;
light_state_t legacyState {
.color = state.color,
.flashMode = static_cast<int>(state.flashMode),
.flashOnMS = state.flashOnMs,
.flashOffMS = state.flashOffMs,
.brightnessMode = static_cast<int>(state.brightnessMode),
};
int ret = hwLight->set_light(hwLight, &legacyState);
switch (ret) {
case -ENOSYS:
return Status::BRIGHTNESS_NOT_SUPPORTED;
case 0:
return Status::SUCCESS;
default:
return Status::UNKNOWN;
}
}
7.【HAL 实现】lights.c.传统 HAL 库
/*
* The lights Module
*/
struct hw_module_t HAL_MODULE_INFO_SYM = {
.tag = HARDWARE_MODULE_TAG,
.version_major = 1,
.version_minor = 0,
.id = LIGHTS_HARDWARE_MODULE_ID,
.name = "lights Module",
.author = "Google, Inc.",
.methods = &lights_module_methods,
};
/**
* module methods
*/
/** Open a new instance of a lights device using name */
static int open_lights(const struct hw_module_t* module, char const* name,
struct hw_device_t** device)
{
int (*set_light)(struct light_device_t* dev,
struct light_state_t const* state);
if (0 == strcmp(LIGHT_ID_BACKLIGHT, name)) {
char property[PROPERTY_VALUE_MAX];
property_get("persist.extend.brightness", property, "0");
if(!(strncmp(property, "1", PROPERTY_VALUE_MAX)) ||
!(strncmp(property, "true", PROPERTY_VALUE_MAX))) {
property_get("persist.display.max_brightness", property, "255");
g_brightness_max = atoi(property);
set_brightness_ext_init();
set_light = set_light_backlight_ext;
} else
// 调用接口 set_light , 上层会调用到这里来
set_light = set_light_backlight;
} else if (0 == strcmp(LIGHT_ID_BATTERY, name))
set_light = set_light_battery;
else if (0 == strcmp(LIGHT_ID_NOTIFICATIONS, name))
set_light = set_light_notifications;
else if (0 == strcmp(LIGHT_ID_BUTTONS, name)) {
if (!access(BUTTON_FILE, F_OK)) {
// enable light button when the file is present
set_light = set_light_buttons;
} else {
return -EINVAL;
}
}
else if (0 == strcmp(LIGHT_ID_ATTENTION, name))
set_light = set_light_attention;
else
return -EINVAL;
pthread_once(&g_init, init_globals);
struct light_device_t *dev = malloc(sizeof(struct light_device_t));
if(!dev)
return -ENOMEM;
memset(dev, 0, sizeof(*dev));
dev->common.tag = HARDWARE_DEVICE_TAG;
dev->common.version = LIGHTS_DEVICE_API_VERSION_2_0;
dev->common.module = (struct hw_module_t*)module;
dev->common.close = (int (*)(struct hw_device_t*))close_lights;
dev->set_light = set_light;
*device = (struct hw_device_t*)dev;
return 0;
}
# 更新灯则通过 sys/class/led/xxx/bright 来操作的
// char const*const RED_LED_FILE = "/sys/class/leds/red/brightness";
set_speaker_light_locked(struct light_device_t* dev,
struct light_state_t const* state)
write_int(RED_LED_FILE, 0);
int bytes = snprintf(buffer, sizeof(buffer), "%d\n", value);
ssize_t amt = write(fd, buffer, (size_t)bytes);
8.【内核实现】leds-qpnp.c
【充电 CHG_LED 可用红灯配置流程】：
// Msm8937-pmi8940-mtp.dtsi (kernel\msm-3.18\arch\arm64\boot\dts\qcom)
&pmi8940_charger {
qcom,battery-data = <&mtp_batterydata>;
qcom,chg-led-sw-controls;
qcom,chg-led-support;
};
解析使用位置：Qpnp-smbcharger.c (kernel\msm-3.18\drivers\power)
static int __init smbchg_init(void)
// static struct spmi_driver smbchg_driver = {
// .driver = {
// .name = "qpnp-smbcharger",
// .owner = THIS_MODULE,
// .of_match_table = smbchg_match_table,
// .pm = &smbchg_pm_ops,
// },
// .probe = smbchg_probe,
// .remove = smbchg_remove,
// .shutdown = smbchg_shutdown,
// };
return spmi_driver_register(&smbchg_driver);
smbchg_probe(struct spmi_device *spmi)
smb_parse_dt(struct smbchg_chip *chip)
chip->cfg_chg_led_support = of_property_read_bool(node, "qcom,chg-led-support");
。。。
if (chip->cfg_chg_led_support && chip->schg_version == QPNP_SCHG_LITE)
rc = smbchg_register_chg_led(chip);
chip->led_cdev.name = "red";
chip->led_cdev.brightness_set = smbchg_chg_led_brightness_set;
chip->led_cdev.brightness_get = smbchg_chg_led_brightness_get;
rc = led_classdev_register(chip->dev, &chip->led_cdev);