Android system ：灯光系统_HAL_lights

一、android灯光系统框架：

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

二、代码lights.c：

/*
 * Copyright (C) 2008 The Android Open Source Project
 * Copyright (C) 2011 Diogo Ferreira <defer@cyanogenmod.com>
 * Copyright (C) 2012 Andreas Makris <andreas.makris@gmail.com>
 * Copyright (C) 2012 The CyanogenMod Project <http://www.cyanogenmod.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_NDEBUG 0
#define LOG_TAG "lights"
#include <cutils/log.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <hardware/lights.h>

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";

/* Synchronization primities */
static pthread_once_t g_init = PTHREAD_ONCE_INIT;
static pthread_mutex_t g_lock = PTHREAD_MUTEX_INITIALIZER;
/* Mini-led state machine */
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 = ;
    fd = open(path, O_RDWR);
    if (fd < ) {
        if (already_warned == ) {
            ALOGE("write_int failed to open %s\n", path);
            already_warned = ;
        }
        return -errno;
    }
    char buffer[];
    int bytes = snprintf(buffer, sizeof(buffer), "%d\n", value);
    int written = write (fd, buffer, bytes);
    close(fd);
    return written == - ? -errno : ;
}
static int write_string (const char *path, const char *value) {
    int fd;
    static int already_warned = ;
    fd = open(path, O_RDWR);
    if (fd < ) {
        if (already_warned == ) {
            ALOGE("write_string failed to open %s\n", path);
            already_warned = ;
        }
        return -errno;
    }
    char buffer[];
    int bytes = snprintf(buffer, sizeof(buffer), "%s\n", value);
    int written = write (fd, buffer, bytes);
    close(fd);
    return written == - ? -errno : ;
}
/* Color tools */
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 ((*((color>>)&0x00ff))
            + (*((color>>)&0x00ff)) + (*(color&0x00ff))) >> ;
}
/* The actual lights controlling section */
static int set_light_backlight (struct light_device_t *dev, struct light_state_t const *state) {
    int brightness = rgb_to_brightness(state);
    ALOGV("%s brightness=%d color=0x%08x", __func__,brightness,state->color);
    pthread_mutex_lock(&g_lock);

    /* brightness 0-255 */
    /* LCD_BACKLIGHT_FILE能接收是0-127 */

    write_int (LCD_BACKLIGHT_FILE, brightness/);

    pthread_mutex_unlock(&g_lock);
    return ;
}
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 >> ) & 0xFF;
    g = (state->color >> ) & 0xFF;
    b = (state->color) & 0xFF;
    delayOn = state->flashOnMS;
    delayOff = state->flashOffMS;
    if (state->flashMode != LIGHT_FLASH_NONE) {
        write_string (RED_LED_FILE_TRIGGER, "timer");
        write_string (GREEN_LED_FILE_TRIGGER, "timer");
        write_string (BLUE_LED_FILE_TRIGGER, "timer");
        write_int (RED_LED_FILE_DELAYON, delayOn);
        write_int (GREEN_LED_FILE_DELAYON, delayOn);
        write_int (BLUE_LED_FILE_DELAYON, delayOn);
        write_int (RED_LED_FILE_DELAYOFF, delayOff);
        write_int (GREEN_LED_FILE_DELAYOFF, delayOff);
        write_int (BLUE_LED_FILE_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)) {
        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 const* state) {

    ALOGV("%s flashMode=%d onMS = %d offMS = %d color=0x%08x", __func__,state->flashMode,state->flashOnMS,state->flashOffMS,state->color);

    pthread_mutex_lock (&g_lock);
    g_battery = *state;
    handle_shared_battery_locked(dev);
    pthread_mutex_unlock (&g_lock);
    return ;
}
static int set_light_notifications (struct light_device_t *dev, struct light_state_t const* state) {
    ALOGV("%s flashMode=%d onMS = %d offMS = %d color=0x%08x", __func__,state->flashMode,state->flashOnMS,state->flashOffMS,state->color);
    pthread_mutex_lock (&g_lock);
    g_notification = *state;
    handle_shared_battery_locked(dev);
    pthread_mutex_unlock (&g_lock);
    return ;
}
/* Initializations */
void init_globals () {
    pthread_mutex_init (&g_lock, NULL);
}
/* Glueing boilerplate */
static int close_lights (struct light_device_t *dev) {
    if (dev)
        free(dev);
    return ;
}
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 ( == strcmp(LIGHT_ID_BACKLIGHT, name)) {
        set_light = set_light_backlight;
    }
    else if ( == strcmp(LIGHT_ID_BATTERY, name)) {
        set_light = set_light_battery;
    }
    else if ( == 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));
    memset(dev, , sizeof(*dev));
    dev->common.tag     = HARDWARE_DEVICE_TAG;
    dev->common.version = ;
    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 ;
}
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 = ,
    .version_minor = ,
    .id = LIGHTS_HARDWARE_MODULE_ID,
    .name = "Sony lights module",
    .author = "Diogo Ferreira <defer@cyanogenmod.com>, Andreas Makris <Andreas.Makris@gmail.com>",
    .methods = &lights_module_methods,
};

三、Android.mk

# Copyright (C)  The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := lights.tiny4412

# HAL module implementation stored in
# hw/<VIBRATOR_HARDWARE_MODULE_ID>.default.so
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)