aidl: light: Rewrite backlight support

* This properly handles max brightness node

Change-Id: I8afcf4bb7cef9c71d9a03bac7e118b8d9cb0565b

aidl/light/Android.bp

@@ -1,5 +1,5 @@
 //
-// Copyright (C) 2021 The LineageOS Project
+// Copyright (C) 2021-2022 The LineageOS Project
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -10,6 +10,7 @@ cc_binary {
     init_rc: ["android.hardware.light-service.xiaomi.rc"],
     vintf_fragments: ["android.hardware.light-service.xiaomi.xml"],
     srcs: [
+        "Backlight.cpp",
         "Lights.cpp",
         "LED.cpp",
         "Utils.cpp",

aidl/light/Backlight.cpp

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2022 The LineageOS Project
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "Backlight.h"
+
+#include "LED.h"
+
+namespace aidl {
+namespace android {
+namespace hardware {
+namespace light {
+
+class BacklightBrightness : public BacklightDevice {
+public:
+    BacklightBrightness(std::string name) : mBasePath(mkBacklightBasePath + name + "/") {
+        if (!readFromFile(mBasePath + "max_brightness", &mMaxBrightness)) {
+            mMaxBrightness = kDefaultMaxBrightness;
+        }
+    };
+
+    void setBacklight(uint8_t value) {
+        writeToFile(mBasePath + "brightness", value * mMaxBrightness / 0xFF);
+    }
+
+    bool exists() {
+        return fileWriteable(mBasePath + "brightness");
+    }
+private:
+    std::string mBasePath;
+    uint32_t mMaxBrightness;
+
+    inline static const std::string mkBacklightBasePath = "/sys/class/backlight/";
+    inline static const uint32_t kDefaultMaxBrightness = 255;
+};
+
+class LEDBacklight : public BacklightDevice {
+public:
+    LEDBacklight(std::string type) : mLED(type) {};
+
+    void setBacklight(uint8_t value) {
+        mLED.setBrightness(value);
+    }
+
+    bool exists() {
+        return mLED.exists();
+    }
+private:
+    LED mLED;
+};
+
+static const std::string kBacklightDevices[] = {
+    "panel0-backlight",
+};
+
+static const std::string kLedDevices[] = {
+    "lcd-backlight",
+};
+
+BacklightDevice *getBacklightDevice() {
+    for (auto &device : kBacklightDevices) {
+        auto backlight = new BacklightBrightness(device);
+        if (backlight->exists()) {
+            return backlight;
+        }
+        delete backlight;
+    }
+
+    for (auto& device : kLedDevices) {
+        auto backlight = new LEDBacklight(device);
+        if (backlight->exists()) {
+            return backlight;
+        }
+        delete backlight;
+    }
+
+    return nullptr;
+}
+
+} // namespace light
+} // namespace hardware
+} // namespace android
+} // namespace aidl

aidl/light/Backlight.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2022 The LineageOS Project
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "Utils.h"
+
+namespace aidl {
+namespace android {
+namespace hardware {
+namespace light {
+
+class BacklightDevice {
+public:
+    virtual ~BacklightDevice() = default;
+
+    virtual void setBacklight(uint8_t value) = 0;
+    virtual bool exists() = 0;
+};
+
+BacklightDevice *getBacklightDevice();
+
+} // namespace light
+} // namespace hardware
+} // namespace android
+} // namespace aidl

aidl/light/Lights.cpp

@@ -15,11 +15,6 @@ namespace android {
 namespace hardware {
 namespace light {
 
-static const std::string kAllBacklightPaths[] = {
-    "/sys/class/backlight/panel0-backlight/brightness",
-    "/sys/class/leds/lcd-backlight/brightness",
-};
-
 static const std::string kAllButtonsPaths[] = {
     "/sys/class/leds/button-backlight/brightness",
     "/sys/class/leds/button-backlight1/brightness",
@@ -48,13 +43,9 @@ static const HwLight kButtonsHwLight = AutoHwLight(LightType::BUTTONS);
 static const HwLight kNotificationHwLight = AutoHwLight(LightType::NOTIFICATIONS);
 
 Lights::Lights() {
-    for (auto& backlight : kAllBacklightPaths) {
-        if (!fileWriteable(backlight))
-            continue;
-
-        mBacklightPath = backlight;
+    mBacklightDevice = getBacklightDevice();
+    if (mBacklightDevice) {
         mLights.push_back(kBacklightHwLight);
-        break;
     }
 
     for (auto& buttons : kAllButtonsPaths) {
@@ -80,8 +71,8 @@ ndk::ScopedAStatus Lights::setLightState(int32_t id, const HwLightState& state)
     LightType type = static_cast<LightType>(id);
     switch (type) {
         case LightType::BACKLIGHT:
-            if (!mBacklightPath.empty())
-                writeToFile(mBacklightPath, color.toBrightness());
+            if (mBacklightDevice)
+                mBacklightDevice->setBacklight(color.toBrightness());
             break;
         case LightType::BUTTONS:
             for (auto& buttons : mButtonsPaths)

aidl/light/Lights.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2021 The LineageOS Project
+ * Copyright (C) 2021-2022 The LineageOS Project
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -8,6 +8,7 @@
 
 #include <aidl/android/hardware/light/BnLights.h>
 #include <mutex>
+#include "Backlight.h"
 
 using ::aidl::android::hardware::light::HwLightState;
 using ::aidl::android::hardware::light::HwLight;
@@ -28,7 +29,7 @@ private:
 
     std::vector<HwLight> mLights;
 
-    std::string mBacklightPath;
+    BacklightDevice *mBacklightDevice;
     std::vector<std::string> mButtonsPaths;
     bool mWhiteLED;
 

aidl/light/android.hardware.light-service.xiaomi.rc

@@ -1,4 +1,5 @@
 on early-boot
+    # Notification LEDs
     chown system system /sys/class/leds/red/blink
     chown system system /sys/class/leds/red/breath
     chown system system /sys/class/leds/red/brightness
@@ -19,9 +20,14 @@ on early-boot
     chown system system /sys/class/leds/white/brightness
     chown system system /sys/class/leds/white/max_brightness
 
-    chown system system /sys/class/leds/lcd-backlight/brightness
+    # Backlight
     chown system system /sys/class/backlight/panel0-backlight/brightness
+    chown system system /sys/class/backlight/panel0-backlight/max_brightness
 
+    chown system system /sys/class/leds/lcd-backlight/brightness
+    chown system system /sys/class/leds/lcd-backlight/max_brightness
+
+    # Buttons
     chown system system /sys/class/leds/button-backlight/brightness
     chown system system /sys/class/leds/button-backlight1/brightness