liblights: add support for adjusting notification LED brightness

The old exynos4x12 lights HAL had logic for scaling the brightness of
lights according to the light's type and also scaling each R/G/B colour.

Bring this logic across, and make the battery LED not eye-searing at
night.

Based on work by Daniel Hillenbrand.

REGRESSION-66

Change-Id: Ia6108468f57c3b6c6a1a68da76a1c3362fd982a5

liblights/include/samsung_lights.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2016 The CyanogenMod Project
+ * Copyright (C) 2017 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,4 +30,25 @@
 #define BUTTON_BRIGHTNESS_NODE "/sys/class/sec/sec_touchkey/brightness"
 #define LED_BLINK_NODE "/sys/class/sec/led/led_blink"
 
+/*
+ * Brightness adjustment factors
+ *
+ * If one of your device's LEDs is more powerful than the others, use these
+ * values to equalise them. This value is in the range 0.0-1.0.
+ */
+#define LED_ADJUSTMENT_R 1.0
+#define LED_ADJUSTMENT_G 1.0
+#define LED_ADJUSTMENT_B 1.0
+
+/*
+ * Light brightness factors
+ *
+ * It might make sense for all colours to be scaled down (for example, if your
+ * LED is too bright). Use these values to adjust the brightness of each
+ * light. This value is within the range 0-255.
+ */
+#define LED_BRIGHTNESS_BATTERY 255
+#define LED_BRIGHTNESS_NOTIFICATION 255
+#define LED_BRIGHTNESS_ATTENTION 255
+
 #endif // SAMSUNG_LIGHTS_H

liblights/lights.c

@@ -1,6 +1,7 @@
 /*
  * Copyright (C) 2013 The Android Open Source Project
  * Copyright (C) 2015-2016 The CyanogenMod Project
+ * Copyright (C) 2017 The LineageOS Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,6 +45,12 @@ enum component_mask_t {
     COMPONENT_LED = 0x4,
 };
 
+enum light_t {
+    TYPE_BATTERY = 0,
+    TYPE_NOTIFICATION = 1,
+    TYPE_ATTENTION = 2,
+};
+
 // Assume backlight is always supported
 static int hw_components = COMPONENT_BACKLIGHT;
 
@@ -197,10 +204,20 @@ static int write_leds(const struct led_config *led)
     return err;
 }
 
+static int calibrate_color(int color, int brightness)
+{
+    int red = ((color >> 16) & 0xFF) * LED_ADJUSTMENT_R;
+    int green = ((color >> 8) & 0xFF) * LED_ADJUSTMENT_G;
+    int blue = (color & 0xFF) * LED_ADJUSTMENT_B;
+
+    return (((red * brightness) / 255) << 16) + (((green * brightness) / 255) << 8) + ((blue * brightness) / 255);
+}
+
 static int set_light_leds(struct light_state_t const *state, int type)
 {
     struct led_config *led;
     int err = 0;
+    int adjusted_brightness;
 
     ALOGV("%s: type=%d, color=0x%010x, fM=%d, fOnMS=%d, fOffMs=%d.", __func__,
           type, state->color,state->flashMode, state->flashOnMS, state->flashOffMS);
@@ -230,7 +247,23 @@ static int set_light_leds(struct light_state_t const *state, int type)
         return -EINVAL;
     }
 
-    led->color = state->color & COLOR_MASK;
+    switch (type) {
+    case TYPE_BATTERY:
+        adjusted_brightness = LED_BRIGHTNESS_BATTERY;
+        break;
+    case TYPE_NOTIFICATION:
+        adjusted_brightness = LED_BRIGHTNESS_NOTIFICATION;
+        break;
+    case TYPE_ATTENTION:
+        adjusted_brightness = LED_BRIGHTNESS_ATTENTION;
+        break;
+    default:
+        adjusted_brightness = 255;
+    }
+
+
+
+    led->color = calibrate_color(state->color & COLOR_MASK, adjusted_brightness);
 
     if (led->color > 0) {
         /* This LED is lit. */
@@ -266,13 +299,13 @@ switched:
 static int set_light_leds_battery(struct light_device_t *dev __unused,
                                   struct light_state_t const *state)
 {
-    return set_light_leds(state, 0);
+    return set_light_leds(state, TYPE_BATTERY);
 }
 
 static int set_light_leds_notifications(struct light_device_t *dev __unused,
                                         struct light_state_t const *state)
 {
-    return set_light_leds(state, 1);
+    return set_light_leds(state, TYPE_NOTIFICATION);
 }
 
 static int set_light_leds_attention(struct light_device_t *dev __unused,
@@ -298,7 +331,7 @@ static int set_light_leds_attention(struct light_device_t *dev __unused,
         break;
     }
 
-    return set_light_leds(&fixed, 2);
+    return set_light_leds(&fixed, TYPE_ATTENTION);
 }
 
 static int open_lights(const struct hw_module_t *module, char const *name,