1.新建hardware/libhardware/include/hardware/led_hal.h文件：
#ifndef ANDROID_LED_INTERFACE_H
#define ANDROID_LED_INTERFACE_H
#include <stdint.h>
#include <sys/cdefs.h>
#include <sys/types.h>
#include <hardware/hardware.h>
#define LED_HARDWARE_MODULE_ID "led"
struct led_module_t {
struct hw_module_t common;
};
struct led_device_t {
struct hw_device_t common;
int fd;
int (*led_ctrl)(struct led_device_t* dev, int val);
};
#endif // ANDROID_LED_INTERFACE_H
2.新建hardware/libhardware/modules/led/led_hal.c文件：
#define LOG_TAG "led_device"
#include <cutils/log.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <hardware/led.h>
int led_ctrl (struct led_device_t *dev, int val)
{
int ret;
val = !!val;
ret = write(dev->fd, &val, 1);
if (ret < 0) {
ALOGE("write to /dev/led-dev failed");
return -EBUSY;
}
return 0;
}
int close_led (struct hw_device_t *dev)
{
struct led_device_t *led_dev = (struct led_device_t *)dev;
close(led_dev->fd);
free(led_dev);
return 0;
}
static int open_led (const struct hw_module_t *module, char const *name,
struct hw_device_t **device)
{
int fd;
struct led_device_t *dev;
fd = open("/dev/led-dev", O_RDWR);
if (fd < 0) {
ALOGE("open /dev/led-dev failed");
return -EBUSY;
}
dev = malloc(sizeof(struct led_device_t));
if (!dev) {
ALOGE("malloc failed");
return -ENOMEM;
}
memset(dev, 0, sizeof(*dev));
dev->fd = fd;
dev->common.tag = HARDWARE_DEVICE_TAG;
dev->common.version = 0;
dev->common.module = (struct hw_module_t*)module;
dev->common.close = (int (*)(struct hw_device_t*))close_led;
dev->led_ctrl = led_ctrl;
*device = (struct hw_device_t *)dev;
return 0;
}
static struct hw_module_methods_t led_module_methods = {
.open = open_led,
};
struct led_module_t HAL_MODULE_INFO_SYM = {
common: {
tag: HARDWARE_MODULE_TAG,
version_major: 1,
version_minor: 0,
id: LED_HARDWARE_MODULE_ID,
name: "led Module",
author: "cary.he",
methods: &led_module_methods,
}
};
3.新建hardware/libhardware/modules/led/Android.mk:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := led.default
LOCAL_MODULE_RELATIVE_PATH := hw
LOCAL_C_INCLUDES := hardware/libhardware
LOCAL_SRC_FILES := led_hal.c
LOCAL_SHARED_LIBRARIES := liblog
LOCAL_MODULE_TAGS := userdebug编译：mmm hardware/libhardware/modules/led/
在out/target/product/msm8909/system/lib/hw/下会生成led.default.so文件。
4.新建frameworks/base/services/core/jni/com_android_server_LedService.cpp文件：
#define LOG_TAG "LedServiceJNI"
#include "utils/Log.h"
#include "jni.h"
#include "JNIHelp.h"
#include "android_runtime/AndroidRuntime.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <hardware/hardware.h>
#include <hardware/led.h>
namespace android
{
struct led_device_t *led_dev;
int led_init(JNIEnv *env, jclass clazz)
{
int ret;
struct led_module_t *led_module;
ret = hw_get_module(LED_HARDWARE_MODULE_ID, (const struct hw_module_t **)&led_module);
if (ret) {
ALOGE("hw_get_module failed");
return -EBUSY;
}
ret = led_module->common.methods->open((const struct hw_module_t *)led_module,
NULL, (struct hw_device_t **)&led_dev);
if (ret) {
ALOGE("led module open failed");
return -EBUSY;
}
return 0;
}
int led_ctrl(JNIEnv *env, jclass clazz, jint val)
{
int ret;
ret = led_dev->led_ctrl(led_dev, val);
if (ret) {
ALOGE("led_ctrl failed");
return -EBUSY;
}
return 0;
}
void led_close(JNIEnv *env, jclass clazz)
{
led_dev->common.close((struct hw_device_t *)led_dev);
}
static const JNINativeMethod method_table[] = {
{"init_native", "()I", (void*)led_init },
{"ctrl_native", "(I)I", (void*)led_ctrl },
{"deinit_native", "()V", (void*)led_close},
};
int register_android_server_LedService(JNIEnv *env)
{
return jniRegisterNativeMethods(env, "com/android/server/LedService", method_table, NELEM(method_table));
}
};
5.修改frameworks/base/services/core/jni/onload.cpp文件，增加函数声明和调用：
int register_android_server_Watchdog(JNIEnv* env);
int register_android_server_LedService(JNIEnv *env); register_android_server_Watchdog(env);
register_android_server_LedService(env);
6.修改frameworks/base/services/core/jni/Android.mk文件，增加一行：
$(LOCAL_REL_DIR)/com_android_server_PersistentDataBlockService.cpp \
$(LOCAL_REL_DIR)/com_android_server_LedService.cpp \
$(LOCAL_REL_DIR)/onload.cpp
编译：mmm frameworks/base/services
在out/target/product/msm8909/system/lib/下会生成libandroid_servers.so文件。
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