Android的LCD和键盘 背光亮度设置.doc

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.javaprivate 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.java1.2 设置亮度文件：packages/apps/Settings/src/com/android/settings/BrightnessPreference.javapublic 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：20255;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.javaframeworks/base/core/java/android/os/PowerManager.java2， 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.javapublic void setBacklightBrightness(int brightness) mContext.enforceCallingOrSelfPermission(android.Manifest.permission.DEVICE_POWER, null); / Dont 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CC+代码，setLightBrightness_UNCHECKED原型如下：文件：frameworks/base/servicesjavacomandroidserverHardwareService.javavoid 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 lightsLIGHT_INDEX_BACKLIGHT = get_device(module, LIGHT_ID_BACKLIGHT); devices-lightsLIGHT_INDEX_KEYBOARD = get_device(module, LIGHT_ID_KEYBOARD); devices-lightsLIGHT_INDEX_BUTTONS = get_device(module, LIGHT_ID_BUTTONS); devices-lightsLIGHT_INDEX_BATTERY = get_device(module, LIGHT_ID_BATTERY); devices-lightsLIGHT_INDEX_NOTIFICATIONS = get_device(module, LIGHT_ID_NOTIFICATIONS); devices-lightsLIGHT_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/hwstatic const char *variant_keys = ro.hardware, /* This goes first so that it can pick up a different file on the emulator. */ duct.board, ro.board.platform, ro.arch;static const int HAL_VARIANT_KEYS_COUNT = (sizeof(variant_keys)/sizeof(variant_keys0);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 propPATH_MAX; char pathPATH_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 ; iHAL_VARIANT_KEYS_COUNT+1 ; i+) if (i HAL_VARIANT_KEYS_COUNT) if (property_get(variant_keysi, prop, NULL) = 0) continue; snprintf(path, sizeof(path), %s/%s.%s.so, HAL_LIBRARY_PATH, id, prop); else snprintf(path, sizeof(path), %s/%s.default.so, HAL_LIBRARY_PATH, id); if (access(path, R_OK) continue; /* we found a library matching this id/variant */ break; status = -ENOENT; if (i HAL_VARIANT_KEYS_COUNT+1) /* load the module, if this fails, were doomed, and we should not try * to load a different variant. */ status = load(id, path, module); return status;property_get(variant_keysi, prop, NULL) 会按如下顺序去获取如下变量所对应的值，然后返回给prop：ro.hardware, /* This goes first so that it can pick up a different file on the emulator. */ duct.board, ro.board.platform,ro.arch它们对应的变量为：duct.board=$TARGET_BOOTLOADER_BOARD_NAMEro.board.platform=$TARGET_BOARD_PLATFORM如vendor/htc/dream-open/BoardConfig.mk里定义的TARGET_BOARD_PLATFORM := msm7k，则prop返回” msm7k ”，所以path = /system/lib/hw/lights. msm7k.so，也就是说要获取的硬件模块为lights. msm7k.so。3.2调用硬件setLight_native对应的jni C/C+代码是：文件：frameworks/base/services/jni/com_android_server_HardwareService.cppstatic void setLight_native(JNIEnv *env, jobject clazz, int ptr, int light, int colorARGB, int flashMode, int onMS, int offMS, int brightnessMode) Devices* devices = (Devices*)ptr; light_state_t state; if (light = LIGHT_COUNT | devices-lightslight = 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-lightslight-set_light(devices-lightslight, &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.mkLOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/hwLOCAL_MODULE := lights.$(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-lightsLIGHT_INDEX_BACKLIGHT = get_device(module, LIGHT_ID_BACKLIGHT); devices-lightsLIGHT_INDEX_KEYBOARD = get_device(module, LIGHT_ID_KEYBOARD); devices-lightsLIGHT_INDEX_BUTTONS = get_device(module, LIGHT_ID_BUTTONS); devices-lightsLIGHT_INDEX_BATTERY = get_device(module, LIGHT_ID_BATTERY); devices-lightsLIGHT_INDEX_NOTIFICATIONS = get_device(module, LIGHT_ID_NOTIFICATIONS); devices-lightsLIGHT_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 intrgb_to_brightness(struct light_state_t const* state) int color = state-color & 0x00ffffff; return (77*(color16)&0x00ff) + (150*(color8)&0x00ff) + (29*(color&0x00ff) 8;static intset_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 intrgb_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 kerneldriversledsLed-class.cstatic 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 kerneldriversledsLed-class.cstatic 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, %un, 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: %sn, led_cdev-name); return 0;#ifdef CONFIG_LEDS_TRIGGERSerr_out_led_list: device_remove_file(led_cdev-dev, &dev_attr_brightness); list_del(&led_cdev-node);#endiferr_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 kerneldriversvideomsmMsm_fb.cstatic 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 failedn); 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, /* T