1.1 設置進度條範圍
背光設置是在:設置->聲音和顯示->亮度,通過進度條來設置的。
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);
下面說的有誤:
設置進度條的範圍,BRIGHTNESS_DIM = 20 BRIGHTNESS_ON=255,它們的定義在:
應該是上面的:MINIMUM_BACKLIGHT ,MAXIMUM_BACKLIGHT 的值纔對
frameworks/base/core/java/Android/os/Power.java
1.2 設置亮度
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) {
}
}
由以上代碼可知,brightness的範圍是:20~255;代碼通過服務管理器(ServiceManager)獲得power服務,然後通過power服務設置亮度。
power.setBacklightBrightness的定義在:
frameworks/base/core/java/Android/os/IPowerManager.aidl.java
frameworks/base/core/java/Android/os/PowerManager.java
實現IPowerManager.aidl.java的類:
/frameworks/base/services/java/com/android/server/PowerManagerService.java
2, Power服務
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) {
}
}
電源管理器(powermager)將brightness轉給電源服務,該服務位置如下:
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;
}
}
由以上代碼可知,同時設置了背光、鍵盤、按鈕的亮度。mHardware 是硬件服務,通過該服務調用底層與設備打交道的C/C++代碼,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);
}
參數說明:int light 表示類型,選項如下:
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,選項如下:
/**
* 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;
由代碼:
int b = brightness & 0x000000ff;
b = 0xff000000 | (b << 16) | (b << 8) | b;
可知,亮度值在此進行了修改,即亮度值的格式變成:FFRRGGBB,FF是沒有的,RR、GG、BB分別是256色的紅綠藍,並且紅綠藍的值都是一樣的亮度值。
3 硬件調用
3.1獲取硬件
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獲取ID爲LIGHTS_HARDWARE_MODULE_ID的硬件模塊,該模塊含有6個不同類型的亮度控制。
hw_get_module 的實現原理,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<HAL_VARIANT_KEYS_COUNT+1 ; i++) {
if (i < HAL_VARIANT_KEYS_COUNT) {
if (property_get(variant_keys[i], 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, we're doomed, and we should not try
* to load a different variant. */
status = load(id, path, module);
}
return status;
}
property_get(variant_keys[i], prop, NULL) 會按如下順序去獲取如下變量所對應的值,然後返回給prop:
"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"
它們對應的變量爲:
"ro.product.board=$TARGET_BOOTLOADER_BOARD_NAME"
"ro.board.platform=$TARGET_BOARD_PLATFORM"
如 vendor/htc/dream-open/BoardConfig.mk裏定義的TARGET_BOARD_PLATFORM := msm7k,則prop返回” msm7k ”,所以path = /system/lib/hw/lights. msm7k.so,也就是說要獲取的硬件模塊爲lights. msm7k.so。
3.2調用硬件
setLight_native對應的jni C/C++代碼是:
文件:frameworks/base/services/jni/com_Android_server_HardwareService.cpp
static 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 < 0 || light >= 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);
}
通過light標識找到對應的light設備,然後再設置亮度。
3.3 硬件原型
msm7k的lights對應的硬件原型是在:hardware/msm7k/liblights
文件:hardware/msm7k/liblights/Android.mk
LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/hw
LOCAL_MODULE := lights.$(TARGET_BOARD_PLATFORM)
也就是生成模塊:/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,
};
以上代碼對應的是:
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);
也就是說,對不同的亮度設置給予了不同的設置函數。
舉例,背光設置,背光對應的代碼如下:
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寫入亮度值,然後驅動會根據該文件更改背光的亮度。 LCD_FILE的路徑根據實際情況更改,同時需要在init.rc 修改其權限,使其可寫rgb_to_brightness也根據實際更改,比如要直接亮度值控制,那隻要獲取r,g,b其中的一個值就行了,如:
static int
rgb_to_brightness(struct light_state_t const* state)
{
int color = state->color & 0x000000ff;
return color;
}
4,led類驅動
4.1,驅動創建leds類,系統啓動時執行leds_init在目錄/sys/class/創建子目錄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,調用這個函數就在目錄/sys/class/leds創建子目錄led_cdev->name和屬性文件brightness
對brightness文件寫就執行led_brightness_store,對brightness文件讀就執行led_brightness_show,爲下面的lcd,led註冊做好準備
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驅動調用led_classdev_register,在目錄/sys/class/leds創建子目錄lcd-backlight和屬性文件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;
}
就在目錄/sys/class/leds創建子目錄 lcd-backlight和屬性文件brightness
當按鍵或者來的或者改變lcd亮度時,上層對屬性文件/sys/class/leds/lcd-backlight/brightness寫入背光的亮度數值就
調用led_brightness_store
調用simple_strtoul(buf, &after, 10);將輸入的字符串轉換爲10進制的數字
執行led_set_brightness
執行led_cdev->brightness_set(led_cdev, value
調用msm_fb_set_bl_brightness ,因爲 .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);
將輸入的0--255轉換爲IC的0--bl_max
調用 msm_fb_set_backlight(mfd, bl_lvl, 1);
最終改變LCD的背光驅動電路的設置,調節LCD的背光的亮度
4.4 鍵盤背光燈
上層對屬性文件/sys/class/leds/keyboard-backlight/brightness寫入背光的亮度數值
(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
系統行動執行msm_pmic_led_init(void)
調用 platform_driver_register(&msm_pmic_led_driver);
調用msm_pmic_led_probe
調用 led_classdev_register(&pdev->dev, &msm_kp_bl_led);
就在目錄/sys/class/leds創建子目錄 keyboard-backlight和屬性文件brightness
當按鍵時,上層對屬性文件/sys/class/leds/keyboard-backlight/brightness寫入背光的亮度數值就
調用led_brightness_store
調用simple_strtoul(buf, &after, 10);將輸入的字符串轉換爲10進制的數字
執行led_set_brightness
執行led_cdev->brightness_set(led_cdev, value
調用msm_keypad_bl_led_set ,因爲 .brightness_set = msm_keypad_bl_led_set,
調用 ret = pmic_set_led_intensity(LED_KEYPAD, value / MAX_KEYPAD_BL_LEVEL);
最終改變LED驅動電路的設置,調節LED的亮度