Add support for led_classdev_mc via sysfs

Update the LinuxLEDController to support multicolor LEDs defined by
the Linux kernel. For multicolor LEDs Linux exposes a single
brightness which allows a range of 0 (off) to 255 (max) and a multi_intensity
value that accepts multiple channels of colors. This current implementation
assumes that there are 3 multi_intensity channels between 0 and 255.

https://docs.kernel.org/leds/leds-class-multicolor.html

Note that for now in Linux the brightness value doesn't so much affect
the brightness of the LED as it does apply a coefficient to the individual
channel intensities. For now hard code the brightness to 255 and simply
adjust the intensities to alter the color.

This change should keep the existing sysfs code path as-is and only attempt
to use this new method when a led_rgb_path is present in the config file.

For reference, my OpenRGB.json has the following lines:
`    "LinuxLEDDevices" : {
        "devices": [
            {
                "name": "Fan LED 1",
                "rgb_path": "/sys/class/leds/rgb:programming-0/"
            }
        ]
    }`

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>

Controllers/LinuxLEDController/LinuxLEDControllerDetect_Linux.cpp

@@ -42,6 +42,7 @@ void DetectLinuxLEDControllers()
             std::string red_path;
             std::string green_path;
             std::string blue_path;
+            std::string rgb_path;
 
             if(linux_led_settings["devices"][device_idx].contains("name"))
             {
@@ -63,10 +64,16 @@ void DetectLinuxLEDControllers()
                 blue_path = linux_led_settings["devices"][device_idx]["blue_path"];
             }
 
+            if(linux_led_settings["devices"][device_idx].contains("rgb_path"))
+            {
+                rgb_path = linux_led_settings["devices"][device_idx]["rgb_path"];
+            }
+
             LinuxLEDController*     controller     = new LinuxLEDController(name);
             controller->OpenRedPath(red_path);
             controller->OpenGreenPath(green_path);
             controller->OpenBluePath(blue_path);
+            controller->OpenRgbPath(rgb_path);
 
             RGBController_LinuxLED* rgb_controller = new RGBController_LinuxLED(controller);
 

Controllers/LinuxLEDController/LinuxLEDController_Linux.cpp

@@ -41,6 +41,11 @@ std::string LinuxLEDController::GetBluePath()
     return(led_b_path);
 }
 
+std::string LinuxLEDController::GetRgbPath()
+{
+    return(led_rgb_path);
+}
+
 void LinuxLEDController::OpenRedPath(std::string red_path)
 {
     led_r_path = red_path;
@@ -59,29 +64,54 @@ void LinuxLEDController::OpenBluePath(std::string blue_path)
     led_b_brightness.open(led_b_path + "brightness");
 }
 
+void LinuxLEDController::OpenRgbPath(std::string rgb_path)
+{
+    led_rgb_path = rgb_path;
+    led_rgb_brightness.open(led_rgb_path + "brightness");
+    led_rgb_color.open(led_rgb_path + "multi_intensity");
+}
+
 void LinuxLEDController::SetRGB(unsigned char red, unsigned char grn, unsigned char blu)
 {
     std::string brightness_str;
 
-    /*-------------------------------------------------------------*\
-    | My phone LED that I tested this on shuts down if you set zero |
-    \*-------------------------------------------------------------*/
-    if(red == 0) red = 1;
-    if(grn == 0) grn = 1;
-    if(blu == 0) blu = 1;
+    if (led_rgb_path.empty()) {
+        /*-------------------------------------------------------------*\
+        | My phone LED that I tested this on shuts down if you set zero |
+        \*-------------------------------------------------------------*/
+        if(red == 0) red = 1;
+        if(grn == 0) grn = 1;
+        if(blu == 0) blu = 1;
 
-    brightness_str = std::to_string((unsigned int)red);
+        brightness_str = std::to_string((unsigned int)red);
 
-    led_r_brightness.write(brightness_str.c_str(), brightness_str.length());
-    led_r_brightness.flush();
+        led_r_brightness.write(brightness_str.c_str(), brightness_str.length());
+        led_r_brightness.flush();
 
-    brightness_str = std::to_string((unsigned int)grn);
+        brightness_str = std::to_string((unsigned int)grn);
 
-    led_g_brightness.write(brightness_str.c_str(), brightness_str.length());
-    led_g_brightness.flush();
+        led_g_brightness.write(brightness_str.c_str(), brightness_str.length());
+        led_g_brightness.flush();
 
-    brightness_str = std::to_string((unsigned int)blu);
+        brightness_str = std::to_string((unsigned int)blu);
 
-    led_b_brightness.write(brightness_str.c_str(), brightness_str.length());
-    led_b_brightness.flush();
+        led_b_brightness.write(brightness_str.c_str(), brightness_str.length());
+        led_b_brightness.flush();
+    }
+
+    else {
+        /*
+         * For the led_classdev_mc brightness just aplies a coefficient to the
+         * multi_intensity. Set brightness to maximum and use the RGB values
+         * directly instead.
+         */
+        brightness_str = std::to_string((unsigned int)255);
+        led_rgb_brightness.write(brightness_str.c_str(), brightness_str.length());
+        led_rgb_brightness.flush();
+        brightness_str = std::to_string((unsigned int)red) + " " \
+            + std::to_string((unsigned int)grn) + " " \
+            + std::to_string((unsigned int)blu);
+        led_rgb_color.write(brightness_str.c_str(), brightness_str.length());
+        led_rgb_color.flush();
+    }
 }

Controllers/LinuxLEDController/LinuxLEDController_Linux.h

@@ -24,10 +24,12 @@ public:
     std::string GetRedPath();
     std::string GetBluePath();
     std::string GetGreenPath();
+    std::string GetRgbPath();
 
     void OpenRedPath(std::string red_path);
     void OpenGreenPath(std::string green_path);
     void OpenBluePath(std::string blue_path);
+    void OpenRgbPath(std::string rgb_path);
 
     void SetRGB(unsigned char red, unsigned char grn, unsigned char blu);
 
@@ -35,8 +37,11 @@ private:
     std::string     led_r_path;
     std::string     led_g_path;
     std::string     led_b_path;
+    std::string     led_rgb_path;
     std::ofstream   led_r_brightness;
     std::ofstream   led_g_brightness;
     std::ofstream   led_b_brightness;
+    std::ofstream   led_rgb_brightness;
+    std::ofstream   led_rgb_color;
     std::string     name;
 };

Controllers/LinuxLEDController/RGBController_LinuxLED_Linux.cpp

@@ -32,8 +32,8 @@ RGBController_LinuxLED::RGBController_LinuxLED(LinuxLEDController* controller_pt
 
     location            = "R: " + controller->GetRedPath() + "\r\n" +
                           "G: " + controller->GetGreenPath() + "\r\n" +
-                          "B: " + controller->GetBluePath();
-
+                          "B: " + controller->GetBluePath() + "\r\n" +
+                          "M: " + controller->GetRgbPath();
     mode Direct;
     Direct.name         = "Direct";
     Direct.value        = 0;