第4课第3节_Android灯光系统_编写HAL_lights.c

JNI文件：com_Android_server_LedService.cpp

注册本地方法，会加载HAL文件：

3. 编写android灯光系统的hal程序

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

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

HAL: lights.c

把新文件上传到服务器, 所在目录:
hardware/libhardware/modules/lights/led_hal.c
hardware/libhardware/modules/lights/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
LOCAL_C_INCLUDES := hardware/libhardware
LOCAL_SRC_FILES := lights.c
LOCAL_SHARED_LIBRARIES := liblog
LOCAL_MODULE_TAGS := eng
include $(BUILD_SHARED_LIBRARY)

修改
vi vendor/friendly-arm/tiny4412/device-tiny4412.mk

ifeq ($(BOARD_USES_PWMLIGHTS),false)
#PRODUCT_COPY_FILES += #       $(VENDOR_PATH)/proprietary/lights.tiny4412.so:system/lib/hw/lights.tiny4412.so
endif

编译：执行mmm命令之前先执行这几个命令：

$ mmm hardware/libhardware/modules/lights
$ make snod
$ ./gen-img.sh

用这个命令确保我们提供的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

没有修改代码进行强制编译 -B

内核也需要修改：修改权限
1. drivers/leds/led-class.c: 0644 改为 0666
static struct device_attribute led_class_attrs[] = {
    __ATTR(brightness, 0666, led_brightness_show, led_brightness_store),
    __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
#ifdef CONFIG_LEDS_TRIGGERS
    __ATTR(trigger, 0666, led_trigger_show, led_trigger_store),
#endif
    __ATTR_NULL,
};

2. drivers/leds/ledtrig-timer.c: 0644 改为 0666
#if defined(CONFIG_MACH_IPCAM)
static DEVICE_ATTR(delay_on, 0666, led_delay_on_show, led_delay_on_store);
static DEVICE_ATTR(delay_off, 0666, led_delay_off_show, led_delay_off_store);
#else
static DEVICE_ATTR(delay_on, 0666, led_delay_on_show, led_delay_on_store);
static DEVICE_ATTR(delay_off, 0666, led_delay_off_show, led_delay_off_store);
#endif

make zImage

用这个命令确保我们提供的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

logcat lights:V *:S