8.3 Android灯光系统_编写HAL_lights.c
注意在led-classes.c中定义的led_class_attrs[]所建立的文件的属性应该改为0666,否则应用程序无权操作它
同时ledtrig-time.c里面对应新建的那几个delay_on/delay_off也要改为0666,这样才能写它
Java: frameworks/base/services/core/java/com/android/server/lights/LightsService.java
JNI: frameworks/base/services/core/jni/com_android_server_lights_LightsService.cpp
Hal: lights.c //参考google上搜索到的lights.c,我们的开发上只有HAL的so库，在vendor/friendly-arm/tiny4412/proprietary/lights_tiny4412.so
默认配色：frameworks/base/core/res/res/values/config.xml
电池灯：frameworks/base/services/core/java/com/android/server/BatteryService.java
通知灯：frameworks/base/services/core/java/com/android/server/notification/NotificationManagerService.java
怎么写LIGHTS HAL
a. 实现一个名为HMI的hw_module_t结构体
b. 实现一个open函数, 它会根据name返回一个light_device_t结构体
c. 实现多个light_device_t结构体，每一个对应一个DEVICE
light_device_t结构体里第1个成员是hw_device_t结构体, 紧接着一个set_light函数
设置LED状态：
struct light_state_t {
/**
* The color of the LED in ARGB.
*
* Do your best here.
* - If your light can only do red or green, if they ask for blue,
* you should do green.
* - If you can only do a brightness ramp, then use this formula:
* unsigned char brightness = ((77*((color>>16)&0x00ff))
* + (150*((color>>8)&0x00ff)) + (29*(color&0x00ff))) >> 8;
* - If you can only do on or off, 0 is off, anything else is on.
*
* The high byte should be ignored. Callers will set it to 0xff (which
* would correspond to 255 alpha).
*/
unsigned int color; // 把灯设为什么颜色, 或 把LCD的亮度设为什么
/**
* See the LIGHT_FLASH_* constants
*/
int flashMode; // 是否闪烁, LIGHT_FLASH_NONE表示不闪
int flashOnMS; // 亮的时间
int flashOffMS;// 灭的时间
/**
* Policy used by the framework to manage the light's brightness.
* Currently the values are BRIGHTNESS_MODE_USER and BRIGHTNESS_MODE_SENSOR.
*/
int brightnessMode; // 表示LCD的背光亮度模式
};
lights.c文件
注意在led-classes.c中定义的led_class_attrs[]所建立的文件的属性应该改为0666,否则应用程序无权操作它
#define LOG_TAG “lights”
#define LOG_NDEBUG 0 //加上这句就可以用ALOGV来打印了，否则打印信息被忽略
#include <hardware/led_hal.h>
#include <hardware/hardware.h>
......还有很多头文件.........
//HAL里面操作led等就是往这些文件里面写值来完成的
char const*const RED_LED_FILE = "sys/class/leds/led1/brightness";
char const*const GREEN_LED_FILE = "sys/class/leds/led2/brightness";
char const*const BLUE_LED_FILE = "sys/class/leds/led3/brightness";
char const*const RED_LED_FILE_TRIGGER = "sys/class/leds/led1/trigger";
char const*const GREEN_LED_FILE_TRIGGER = "sys/class/leds/led2/trigger";
char const*const BLUE_LED_FILE_TRIGGER = "sys/class/leds/led3/trigger";
char const*const RED_LED_FILE_DELAYON = "sys/class/leds/led1/delay_on";
char const*const GREEN_LED_FILE_DELAYON = "sys/class/leds/led2/delay_on";
char const*const BLUE_LED_FILE_DELAYON = "sys/class/leds/led3/delay_on";
char const*const RED_LED_FILE_DELAYOFF = "sys/class/leds/led1/delay_off";
char const*const GREEN_LED_FILE_DELAYOFF = "sys/class/leds/led2/delay_off";
char const*const BLUE_LED_FILE_DELAYOFF = "sys/class/leds/led3/delay_off";
char const*const LCD_BACKLIGHT_FILE = "/dev/backlight-1wire";//反汇编厂家提供的HAL层SO，lights_tiny4412.so,可以看到对背光灯的操作是该文件，在内核中搜索“backlight-1wire”,发现其是对应drivers/input/touchscreen/tiny4412_1wire_host.c中注册的设备，其是一个miscdevice，提供了file_operation结构体
static pthread_one_t g_init = PTHREAD_ONCE_INIT;
static pthread_mutex_t g_lock = PTHREAD_MUTEX_INITIALIZER;
//通知灯和电池灯公用一个硬件
static struct light_state_t g_notification;
static struct light_state_t g_battery;
static int write_int(const char *path,int value){
int fd;
static int already_warned = 0;
fd = open(path,O_RDWR);
if(fd<0)
{
if(already_warned == 0)
{
already_warned = 1;
}
return -errno;
}
char buffer[20];
int bytes = snprintf(buffer,sizeof(buffer),"%s\n",value);
int written = write(fd,buffer,bytes);
close(fd);
return written == -1?-errno:0;
}
static int write_string(const char *path,const char *value){
int fd;
static int already_warned = 0;
fd = open(path,O_RDWR);
if(fd<0)
{
if(already_warned == 0)
{
already_warned = 1;
}
return -errno;
}
char buffer[20];
int bytes = snprintf(buffer,sizeof(buffer),"%s\n",value);
int written = write(fd,buffer,bytes);
close(fd);
return written == -1?-errno:0;
}
static int is_lit(struct light_state_t const * state){
return state->color & 0x00ffffff;
}
static int rgb_to_brightness(struct light_state_t const * state){
int color = state->color & 0x00ffffff;
return ((77*((color>>16)&0x00ff))+(150*((color>>8)&0x00ff))+(29*(color&0x00ff)))>>
}
static int set_light_backlight(struct light_device_t *dev,,struct light_state_t *state){
int brightness = rgb_to_brightness(state);
pthread_mutex_lock(&g_lock);
//brightness在这里的范围是0-255，但是设备文件能接受的是0-127
write_int(LCD_BACKLIGHT_FILR,brightness/2);
pthread_mutex_unlock(&g_lock);
return 0;
}
static void set_shared_light_locked(struct light_device_t *dev,struct light_state_t *state){
int r,g,b;
int delayOn,delayOff;
r = (state->color>>16)&0xff;
g = (state->color>>8)&0xff;
b = (state->color)&0xff;
delayOn = state->flashOnMS;
delayOff = state->flashOffMS;
if(state->flashMode != LIGHT_FLASH_NONE){
write_string(RED_LED_FILE_TRIGGER,"trigger");
write_string(GREEN_LED_FILE_TRIGGER,"trigger");
write_string(BLUE_LED_FILE_TRIGGER,"trigger");
write_int(RED_LED_FILR_DELAYON,delayOn);
write_int(GREEN_LED_FILR_DELAYON,delayOn);
write_int(BLUE_LED_FILR_DELAYON,delayOn);
write_int(RED_LED_FILR_DELAYOFF,delayOff);
write_int(GREEN_LED_FILR_DELAYOFF,delayOff);
write_int(BLUE_LED_FILR_DELAYOFF,delayOff);
}else{
write_string(RED_LED_FILE_TRIGGER,"none");
write_string(GREEN_LED_FILE_TRIGGER,"none");
write_string(BLUE_LED_FILE_TRIGGER,"none");
}
write_int(RED_LED_FILE,r);
write_int(GREEN_LED_FILE,g);
write_int(BLUE_LED_FILE,b)
}
static void handle_shared_battery_locked(struct light_device_t *dev){
if(is_lit(&g_notification)){//优先设置通知灯
set_shared_light_locked(dev,&g_notification);
}else{
set_shared_light_locked(dev,&g_battery);
}
}
static int set_light_battery((struct light_device_t *dev,struct light_state_t *state){
pthread_mutex_lock(&g_lock);
g_battery = *state;
handle_shared_battery_locked(dev);
pthread_mutex_unlock(&g_lock);
return 0;
}
static int set_light_notifications((struct light_device_t *dev,struct light_state_t *state){
pthread_mutex_lock(&g_lock);
g_notification = *state;
handle_shared_battery_locked(dev);
pthread_mutex_unlock(&g_lock);
return 0;
}
void init_globals(){
pthread_mutex_init(&g_lock,NULL);
}
static int close_lights(struct light_device_t* dev){
}
static int open_lights(const struct hw_module_t *module,const char *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))
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{
return -EINVAL;
}
pthread_once(&g_init,init_globals);
struct light_device_t *dev = malloc(sizeof(struct light_device_t),GPKERNEL);
memset(dev,0,sizeof(*dev));
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_lights;
dev->set_light = set_light;
*device = (struct hw_device_t*)dev;
return 0;
*device = &led_dev //led_dev 的第一个成员就是hw_device_t ，他们地址一样
}
static struct hw_module_methods_t lights_module_methods {
.open = open_lights,
};
struct hw_module_t HAL_MODULE_INFO_SYM = {
.tag = HARDWARE_MODULE_TAG,
.version_major = 1,
.version_minor = 0,
.id = LIGHTS_HARDWARE_MODULE_ID,
.name ="Snoy_lights_module",
.methods = lights_module_methods ;
}
在lights.c下添加Android.mk
Android.mk内容如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := lights.tiny4412;
LOCAL_MODULE_RELATIVE_PATH :=hw //指定了so存在的目录在/system/lib/hw下
LOCAL_C_INCLUDES := hardware/libhardware //头文件
LOCAL__SRC_FILES := lights.c //源文件
LOCAL_SHARED_LIBRARIES := liblog
LOCAL_MODULE_TAGS := eng
include $(BUILD_SHARED_LIBRARY)
上传HAL：lights.c
hardware/libhardware/modules/lights/lights.c
hardware/libhardware/modules/lights/Android.mk
修改：
vi vendor friendly-arm/tiny4412/device-tiny4412.mk
注释掉device-tiny4412.mk里面的(应该是去掉厂家提供的HAL)
ifeq ($(BOARD_USES_PWMLIGHTS),false)
#PRODUCT_COPY_FILES +=\
# $(VENDOR_PATH)/proprietary/lights.tiny4412.so:system/lib/hw/lights.tiny4412.so
endif
编译：
.setenv//先设置环境变量
lunch//执行后选择23 full_tiny4412_eng 这里的eng对应的Android.mk里面设置的eng
mmm hardware/libhardware/modules/lights -B //强制编译C库
make snod
./gen-img.sh
对比下厂家提供HAL和我们自己生成的HAL，会发现不一样，同时该命令也能确保我们提供的lights.c已经编进system.img
diff vendor/friendly-arm/tiny4412/proprietary/lights.tiny4412.so out/target/product/tiny4412/system/lib/hw/lights.tiny4412.so
更新system.img 和上一节中得到的zImage
