[汇总]Android的LCD和键盘 背光亮度设置

[汇总]Android的LCD和键盘 背光亮度设置 Android的LCD和键盘 背光亮度设置 亮度设置 应用设计 1.1 设置进度条范围 背光设置是在:设置->声音和显示->亮度，通过进度条来设置的。 文件:packages/apps/Settings/src/com/android/settings/BrightnessPreference.java private static final int MINIMUM_BACKLIGHT = android.os.Power.BRIGHTNESS_DIM + 10; private static final int MAXIMUM_BACKLIGHT = android.os.Power.BRIGHTNESS_ON; mSeekBar.setMax(MAXIMUM_BACKLIGHT - MINIMUM_BACKLIGHT); 设置进度条的范围，BRIGHTNESS_DIM = 20 BRIGHTNESS_ON=255，它们的定义在: frameworks/base/core/java/android/os/Power.java 1.2 设置亮度 文件:packages/apps/Settings/src/com/android/settings/BrightnessPreference.java public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { setMode(isChecked ? Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC : Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL); if (!isChecked) { setBrightness(mSeekBar.getProgress() + MINIMUM_BACKLIGHT); } } private void setBrightness(int brightness) { try { IPowerManager power = IPowerManager.Stub.asInterface( ServiceManager.getService("power")); if (power != null) { power.setBacklightBrightness(brightness); } } catch (RemoteException doe) { } } 由以上代码可知，brightness的范围是:20~255;代码通过服务管理器(ServiceManager)获得power服务，然后通过power服务设置亮度。 power.setBacklightBrightness的定义在: rameworks/base/core/java/android/os/IPowerManager.aidl.java frameworks/base/core/java/android/os/PowerManager.java 2， Power服务 文件:frameworks/base/core/java/android/os/Power.java /** * Brightness value for dim backlight */ public static final int BRIGHTNESS_DIM = 20; /** * Brightness value for fully on */ public static final int BRIGHTNESS_ON = 255; 文件:frameworks/base/core/java/android/os/PowerManager.java /** * sets the brightness of the backlights (screen, keyboard, button). * * @param brightness value from 0 to 255 * * {@hide} */ public void setBacklightBrightness(int brightness) { try { mService.setBacklightBrightness(brightness); } catch (RemoteException e) { } } 电源管理器(powermager)将brightness转给电源服务，该服务位置如下: 文件:frameworks/base/services/java/com/android/server/PowerManagerService.java public void setBacklightBrightness(int brightness) { mContext.enforceCallingOrSelfPermission(android.Manifest.permission.DEVICE_POWER, null); // Don't let applications turn the screen all the way off brightness = Math.max(brightness, Power.BRIGHTNESS_DIM); mHardware.setLightBrightness_UNCHECKED(HardwareService.LIGHT_ID_BACKLIGHT, brightness, HardwareService.BRIGHTNESS_MODE_USER); mHardware.setLightBrightness_UNCHECKED(HardwareService.LIGHT_ID_KEYBOARD, (mKeyboardVisible ? brightness : 0), HardwareService.BRIGHTNESS_MODE_USER); mHardware.setLightBrightness_UNCHECKED(HardwareService.LIGHT_ID_BUTTONS, brightness, HardwareService.BRIGHTNESS_MODE_USER); long identity = Binder.clearCallingIdentity(); try { mBatteryStats.noteScreenBrightness(brightness); } catch (RemoteException e) { Log.w(TAG, "RemoteException calling noteScreenBrightness on BatteryStatsService", e); } finally { Binder.restoreCallingIdentity(identity); } // update our animation state if (ANIMATE_SCREEN_LIGHTS) { mScreenBrightness.curValue = brightness; mScreenBrightness.animating = false; mScreenBrightness.targetValue = -1; } if (ANIMATE_KEYBOARD_LIGHTS) { mKeyboardBrightness.curValue = brightness; mKeyboardBrightness.animating = false; mKeyboardBrightness.targetValue = -1; } if (ANIMATE_BUTTON_LIGHTS) { mButtonBrightness.curValue = brightness; mButtonBrightness.animating = false; mButtonBrightness.targetValue = -1; } } 由以上代码可知，同时设置了背光、键盘、按钮的亮度。mHardware 是硬件服务，通过该服务调用底层与设备打交道的C\C++代码，setLightBrightness_UNCHECKED原型如下: 文件:frameworks/base/services\java\com\android\server\HardwareService.java void setLightBrightness_UNCHECKED(int light, int brightness, int brightnessMode) { int b = brightness & 0x000000ff; b = 0xff000000 | (b << 16) | (b << 8) | b; setLight_native(mNativePointer, light, b, LIGHT_FLASH_NONE, 0, 0, brightnessMode); } 参数说明:int light 表示类型，选项如下: static final int LIGHT_ID_BACKLIGHT = 0; static final int LIGHT_ID_KEYBOARD = 1; static final int LIGHT_ID_BUTTONS = 2; static final int LIGHT_ID_BATTERY = 3; static final int LIGHT_ID_NOTIFICATIONS = 4; static final int LIGHT_ID_ATTENTION = 5; int brightness 表示亮度值 int brightnessMode 表示亮度的控制模式，选项如下: /** * Light brightness is managed by a user setting. */ static final int BRIGHTNESS_MODE_USER = 0; /** * Light brightness is managed by a light sensor. */ static final int BRIGHTNESS_MODE_SENSOR = 1; 由代码: int b = brightness & 0x000000ff; b = 0xff000000 | (b << 16) | (b << 8) | b; 可知，亮度值在此进行了修改，即亮度值的格式变成:FFRRGGBB，FF是没有的，RR、 GG、BB分别是256色的红绿蓝，并且红绿蓝的值都是一样的亮度值。 3 硬件调用 3.1获取硬件 文件:frameworks/base/services/jni/com_android_server_HardwareService.cpp enum { LIGHT_INDEX_BACKLIGHT = 0, LIGHT_INDEX_KEYBOARD = 1, LIGHT_INDEX_BUTTONS = 2, LIGHT_INDEX_BATTERY = 3, LIGHT_INDEX_NOTIFICATIONS = 4, LIGHT_INDEX_ATTENTION = 5, LIGHT_COUNT }; #define LIGHTS_HARDWARE_MODULE_ID "lights" static jint init_native(JNIEnv *env, jobject clazz) { int err; hw_module_t* module; Devices* devices; devices = (Devices*)malloc(sizeof(Devices)); err = hw_get_module(LIGHTS_HARDWARE_MODULE_ID, (hw_module_t const**)&module); if (err == 0) { devices->lights[LIGHT_INDEX_BACKLIGHT] = get_device(module, LIGHT_ID_BACKLIGHT); devices->lights[LIGHT_INDEX_KEYBOARD] = get_device(module, LIGHT_ID_KEYBOARD); devices->lights[LIGHT_INDEX_BUTTONS] = get_device(module, LIGHT_ID_BUTTONS); devices->lights[LIGHT_INDEX_BATTERY] = get_device(module, LIGHT_ID_BATTERY); devices->lights[LIGHT_INDEX_NOTIFICATIONS] = get_device(module, LIGHT_ID_NOTIFICATIONS); devices->lights[LIGHT_INDEX_ATTENTION] = get_device(module, LIGHT_ID_ATTENTION); } else { memset(devices, 0, sizeof(Devices)); } return (jint)devices; } 用hw_get_module获取ID为LIGHTS_HARDWARE_MODULE_ID的硬件模块，该模块含有6个不同类型的亮度控制。 hw_get_module 的实现原理，如下: 文件:hardware/libhardware/Hardware.c #define HAL_LIBRARY_PATH "/system/lib/hw" static const char *variant_keys[] = { "ro.hardware", /* This goes first so that it can pick up a different file on the emulator. */ "ro.product.board", "ro.board.platform", "ro.arch" }; static const int HAL_VARIANT_KEYS_COUNT = (sizeof(variant_keys)/sizeof(variant_keys[0])); int hw_get_module(const char *id, const struct hw_module_t **module) { int status; int i; const struct hw_module_t *hmi = NULL; char prop[PATH_MAX]; char path[PATH_MAX]; /* * Here we rely on the fact that calling dlopen multiple times on * the same .so will simply increment a refcount (and not load * a new copy of the library). * We also assume that dlopen() is thread-safe. */ /* Loop through the configuration variants looking for a module */ for (i=0 ; i= LIGHT_COUNT || devices->lights[light] == NULL) { return ; } memset(&state, 0, sizeof(light_state_t)); state.color = colorARGB; state.flashMode = flashMode; state.flashOnMS = onMS; state.flashOffMS = offMS; state.brightnessMode = brightnessMode; devices->lights[light]->set_light(devices->lights[light], &state); } 通过light标识找到对应的light设备，然后再设置亮度。 3.3 硬件原型 msm7k的lights对应的硬件原型是在:hardware/msm7k/liblights 文件:hardware/msm7k/liblights/Android.mk LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/hw LOCAL_MODULE := lights.$(TARGET_BOARD_PLATFORM) 也就是生成模块:/system/lib/hw/lights. msm7k.so 文件:hardware/msm7k/liblights/lights.c /** 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)) { set_light = set_light_backlight; } else if (0 == strcmp(LIGHT_ID_KEYBOARD, name)) { set_light = set_light_keyboard; } else if (0 == strcmp(LIGHT_ID_BUTTONS, name)) { set_light = set_light_buttons; } 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_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)); 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; } static struct hw_module_methods_t lights_module_methods = { .open = open_lights, }; 以上代码对应的是: devices->lights[LIGHT_INDEX_BACKLIGHT] = get_device(module, LIGHT_ID_BACKLIGHT); devices->lights[LIGHT_INDEX_KEYBOARD] = get_device(module, LIGHT_ID_KEYBOARD); devices->lights[LIGHT_INDEX_BUTTONS] = get_device(module, LIGHT_ID_BUTTONS); devices->lights[LIGHT_INDEX_BATTERY] = get_device(module, LIGHT_ID_BATTERY); devices->lights[LIGHT_INDEX_NOTIFICATIONS] = get_device(module, LIGHT_ID_NOTIFICATIONS); devices->lights[LIGHT_INDEX_ATTENTION] = get_device(module, LIGHT_ID_ATTENTION); 也就是说，对不同的亮度设置给予了不同的设置函数。 举例，背光设置，背光对应的代码如下: char const*const LCD_FILE = "/sys/class/leds/lcd-backlight/brightness"; 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))) >> 8; } static int set_light_backlight(struct light_device_t* dev, struct light_state_t const* state) { int err = 0; int brightness = rgb_to_brightness(state); pthread_mutex_lock(&g_lock); g_backlight = brightness; err = write_int(LCD_FILE, brightness); if (g_haveTrackballLight) { handle_trackball_light_locked(dev); } pthread_mutex_unlock(&g_lock); return err; } 也就是往文件/sys/class/leds/lcd-backlight/brightness写入亮度值，然后驱动会根据该文件更改背光的亮度。LCD_FILE的路径根据实际情况更改，同时需要在init.rc 修改其权限，使其可写rgb_to_brightness也根据实际更改，比如要直接亮度值控制，那只要获取r,g,b其中的一个值就行了，如: static int rgb_to_brightness(struct light_state_t const* state) { int color = state->color & 0x000000ff; return color; } 4，led类驱动 4.1，驱动创建leds类，系统启动时执行leds_init在目录/sys/class/创建子目录leds kernel\drivers\leds\Led-class.c static int __init leds_init(void) { leds_class = class_create(THIS_MODULE, "leds"); if (IS_ERR(leds_class)) return PTR_ERR(leds_class); leds_class->suspend = led_suspend; leds_class->resume = led_resume; return 0; } 4.2，led_classdev_register，调用这个函数就在目录/sys/class/leds创建子目录led_cdev->name 和属性文件brightness 对brightness文件写就执行led_brightness_store，对brightness文件读就执行led_brightness_show，为下面的lcd，led注册做好准备 kernel\drivers\leds\Led-class.c static ssize_t led_brightness_show(struct device *dev, struct device_attribute *attr, char *buf) { struct led_classdev *led_cdev = dev_get_drvdata(dev); /* no lock needed for this */ led_update_brightness(led_cdev); return sprintf(buf, "%u\n", led_cdev->brightness); } static ssize_t led_brightness_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { struct led_classdev *led_cdev = dev_get_drvdata(dev); ssize_t ret = -EINVAL; char *after; unsigned long state = simple_strtoul(buf, &after, 10); size_t count = after - buf; if (*after && isspace(*after)) count++; if (count == size) { ret = count; if (state == LED_OFF) led_trigger_remove(led_cdev); led_set_brightness(led_cdev, state); } return ret; } static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store); /** * led_classdev_register - register a new object of led_classdev class. * @parent: The device to register. * @led_cdev: the led_classdev structure for this device. */ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) { int rc; led_cdev->dev = device_create(leds_class, parent, 0, led_cdev, "%s", led_cdev->name); if (IS_ERR(led_cdev->dev)) return PTR_ERR(led_cdev->dev); /* register the attributes */ rc = device_create_file(led_cdev->dev, &dev_attr_brightness); if (rc) goto err_out; #ifdef CONFIG_LEDS_TRIGGERS init_rwsem(&led_cdev->trigger_lock); #endif /* add to the list of leds */ down_write(&leds_list_lock); list_add_tail(&led_cdev->node, &leds_list); up_write(&leds_list_lock); led_update_brightness(led_cdev); #ifdef CONFIG_LEDS_TRIGGERS rc = device_create_file(led_cdev->dev, &dev_attr_trigger); if (rc) goto err_out_led_list; led_trigger_set_default(led_cdev); #endif printk(KERN_INFO "Registered led device: %s\n", led_cdev->name); return 0; #ifdef CONFIG_LEDS_TRIGGERS err_out_led_list: device_remove_file(led_cdev->dev, &dev_attr_brightness); list_del(&led_cdev->node); #endif err_out: device_unregister(led_cdev->dev); return rc; } EXPORT_SYMBOL_GPL(led_classdev_register); 4.3，lcd驱动调用led_classdev_register，在目录/sys/class/leds创建子目录lcd-backlight和属 性文件brightness kernel\drivers\video\msm\Msm_fb.c static int lcd_backlight_registered; static void msm_fb_set_bl_brightness(struct led_classdev *led_cdev, enum led_brightness value) { struct msm_fb_data_type *mfd = dev_get_drvdata(led_cdev->dev->parent); int bl_lvl; if (value > MAX_BACKLIGHT_BRIGHTNESS) value = MAX_BACKLIGHT_BRIGHTNESS; /* This maps android backlight level 0 to 255 into driver backlight level 0 to bl_max with rounding */ bl_lvl = (2 * value * mfd->panel_info.bl_max + MAX_BACKLIGHT_BRIGHTNESS) /(2 * MAX_BACKLIGHT_BRIGHTNESS); if (!bl_lvl && value) bl_lvl = 1; msm_fb_set_backlight(mfd, bl_lvl, 1); } static struct led_classdev backlight_led = { .name = "lcd-backlight", .brightness = MAX_BACKLIGHT_BRIGHTNESS, .brightness_set = msm_fb_set_bl_brightness, }; if (!lcd_backlight_registered) { if (led_classdev_register(&pdev->dev, &backlight_led)) printk(KERN_ERR "led_classdev_register failed\n"); else lcd_backlight_registered = 1; } 就在目录/sys/class/leds创建子目录 lcd-backlight和属性文件brightness 当按键或者来的或者改变lcd亮度时，上层对属性文件/sys/class/leds/lcd-backlight/brightness 写入背光的亮度数值就 调用led_brightness_store 调用simple_strtoul(buf, &after, 10);将输入的字符串转换为10进制的数字 执行led_set_brightness 执行led_cdev->brightness_set(led_cdev, value 调用msm_fb_set_bl_brightness ，因为 .brightness_set = msm_fb_set_bl_brightness, /* This maps android backlight level 0 to 255 into driver backlight level 0 to bl_max with rounding */ bl_lvl = (2 * value * mfd->panel_info.bl_max + MAX_BACKLIGHT_BRIGHTNESS) /(2 * MAX_BACKLIGHT_BRIGHTNESS); 将输入的0--255转换为IC的0--bl_max 调用 msm_fb_set_backlight(mfd, bl_lvl, 1); 最终改变LCD的背光驱动电路的设置，调节LCD的背光的亮度 4.4 键盘背光灯 上层对属性文件/sys/class/leds/keyboard-backlight/brightness写入背光的亮度数值 (kernel\drivers\leds\Leds-msm-pmic.c #define MAX_KEYPAD_BL_LEVEL 16 static void msm_keypad_bl_led_set(struct led_classdev *led_cdev, enum led_brightness value) { int ret; ret = pmic_set_led_intensity(LED_KEYPAD, value / MAX_KEYPAD_BL_LEVEL); if (ret) dev_err(led_cdev->dev, "can't set keypad backlight\n"); } static struct led_classdev msm_kp_bl_led = { .name = "keyboard-backlight", .brightness_set = msm_keypad_bl_led_set, .brightness = LED_OFF, }; static int msm_pmic_led_probe(struct platform_device *pdev) { int rc; rc = led_classdev_register(&pdev->dev, &msm_kp_bl_led); if (rc) { dev_err(&pdev->dev, "unable to register led class driver\n"); return rc; } msm_keypad_bl_led_set(&msm_kp_bl_led, LED_OFF); return rc; } static int __devexit msm_pmic_led_remove(struct platform_device *pdev) { led_classdev_unregister(&msm_kp_bl_led); return 0; } #ifdef CONFIG_PM static int msm_pmic_led_suspend(struct platform_device *dev, pm_message_t state) { led_classdev_suspend(&msm_kp_bl_led); return 0; } static int msm_pmic_led_resume(struct platform_device *dev) { led_classdev_resume(&msm_kp_bl_led); return 0; } #else #define msm_pmic_led_suspend NULL #define msm_pmic_led_resume NULL #endif static struct platform_driver msm_pmic_led_driver = { .probe = msm_pmic_led_probe, .remove = __devexit_p(msm_pmic_led_remove), .suspend = msm_pmic_led_suspend, .resume = msm_pmic_led_resume, .driver = { .name = "pmic-leds", .owner = THIS_MODULE, }, }; static int __init msm_pmic_led_init(void) { return platform_driver_register(&msm_pmic_led_driver); } module_init(msm_pmic_led_init); static void __exit msm_pmic_led_exit(void) { platform_driver_unregister(&msm_pmic_led_driver); } module_exit(msm_pmic_led_exit); MODULE_DESCRIPTION("MSM PMIC LEDs driver"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:p 系统行动执行msm_pmic_led_init(void) 调用 platform_driver_register(&msm_pmic_led_driver); 调用msm_pmic_led_probe 调用 led_classdev_register(&pdev->dev, &msm_kp_bl_led); 就在目录/sys/class/leds创建子目录 keyboard-backlight和属性文件brightness 当按键时，上层对属性文件/sys/class/leds/keyboard-backlight/brightness写入背光的亮度数值就 调用led_brightness_store 调用simple_strtoul(buf, &after, 10);将输入的字符串转换为10进制的数字 执行led_set_brightness 执行led_cdev->brightness_set(led_cdev, value 调用msm_keypad_bl_led_set ，因为 .brightness_set = msm_keypad_bl_led_set, 调用 ret = pmic_set_led_intensity(LED_KEYPAD, value / MAX_KEYPAD_BL_LEVEL); 最终改变LED驱动电路的设置，调节LED的亮度