recovery: Porting screensave mode for new platform.

On new board platform the brightness path of
sys/class/leds/lcd-backlight is deprecated,instead of
/sys/class/backlight/panel0-backlight/.

Test: reboot into recovery on sdm845.
Change-Id: Idf0027ab888f9f982a8eef7de230ce3635e7c300
Signed-off-by: katao <[email protected]>

ui.cpp

@@ -48,10 +48,16 @@
 static constexpr int UI_WAIT_KEY_TIMEOUT_SEC = 120;
 static constexpr const char* BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/brightness";
 static constexpr const char* MAX_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/max_brightness";
+static constexpr const char* BRIGHTNESS_FILE_SDM =
+    "/sys/class/backlight/panel0-backlight/brightness";
+static constexpr const char* MAX_BRIGHTNESS_FILE_SDM =
+    "/sys/class/backlight/panel0-backlight/max_brightness";
 
 RecoveryUI::RecoveryUI()
     : brightness_normal_(50),
       brightness_dimmed_(25),
+      brightness_file_(BRIGHTNESS_FILE),
+      max_brightness_file_(MAX_BRIGHTNESS_FILE),
       touch_screen_allowed_(false),
       kTouchLowThreshold(RECOVERY_UI_TOUCH_LOW_THRESHOLD),
       kTouchHighThreshold(RECOVERY_UI_TOUCH_HIGH_THRESHOLD),
@@ -101,12 +107,17 @@ bool RecoveryUI::InitScreensaver() {
   if (brightness_normal_ == 0 || brightness_dimmed_ > brightness_normal_) {
     return false;
   }
-
+  if (access(brightness_file_.c_str(), R_OK | W_OK)) {
+    brightness_file_ = BRIGHTNESS_FILE_SDM;
+  }
+  if (access(max_brightness_file_.c_str(), R_OK)) {
+    max_brightness_file_ = MAX_BRIGHTNESS_FILE_SDM;
+  }
   // Set the initial brightness level based on the max brightness. Note that reading the initial
   // value from BRIGHTNESS_FILE doesn't give the actual brightness value (bullhead, sailfish), so
   // we don't have a good way to query the default value.
   std::string content;
-  if (!android::base::ReadFileToString(MAX_BRIGHTNESS_FILE, &content)) {
+  if (!android::base::ReadFileToString(max_brightness_file_, &content)) {
     PLOG(WARNING) << "Failed to read max brightness";
     return false;
   }
@@ -120,7 +131,7 @@ bool RecoveryUI::InitScreensaver() {
   brightness_normal_value_ = max_value * brightness_normal_ / 100.0;
   brightness_dimmed_value_ = max_value * brightness_dimmed_ / 100.0;
   if (!android::base::WriteStringToFile(std::to_string(brightness_normal_value_),
-                                        BRIGHTNESS_FILE)) {
+                                        brightness_file_)) {
     PLOG(WARNING) << "Failed to set brightness";
     return false;
   }
@@ -430,13 +441,13 @@ int RecoveryUI::WaitKey() {
         // Lower the brightness level: NORMAL -> DIMMED; DIMMED -> OFF.
         if (screensaver_state_ == ScreensaverState::NORMAL) {
           if (android::base::WriteStringToFile(std::to_string(brightness_dimmed_value_),
-                                               BRIGHTNESS_FILE)) {
+                                               brightness_file_)) {
             LOG(INFO) << "Brightness: " << brightness_dimmed_value_ << " (" << brightness_dimmed_
                       << "%)";
             screensaver_state_ = ScreensaverState::DIMMED;
           }
         } else if (screensaver_state_ == ScreensaverState::DIMMED) {
-          if (android::base::WriteStringToFile("0", BRIGHTNESS_FILE)) {
+          if (android::base::WriteStringToFile("0", brightness_file_)) {
             LOG(INFO) << "Brightness: 0 (off)";
             screensaver_state_ = ScreensaverState::OFF;
           }
@@ -451,7 +462,7 @@ int RecoveryUI::WaitKey() {
 
         // Reset the brightness to normal.
         if (android::base::WriteStringToFile(std::to_string(brightness_normal_value_),
-                                             BRIGHTNESS_FILE)) {
+                                             brightness_file_)) {
           screensaver_state_ = ScreensaverState::NORMAL;
           LOG(INFO) << "Brightness: " << brightness_normal_value_ << " (" << brightness_normal_
                     << "%)";

ui.h

@@ -148,6 +148,8 @@ class RecoveryUI {
   // be configured via subclassing. Setting brightness_normal_ to 0 to disable screensaver.
   unsigned int brightness_normal_;
   unsigned int brightness_dimmed_;
+  std::string brightness_file_;
+  std::string max_brightness_file_;
 
   // Whether we should listen for touch inputs (default: false).
   bool touch_screen_allowed_;