AP_Notify: add Led_Sysfs and use in Navio2

Navio2 exports its leds via /sys/class/leds interface. We reuse it in
order not to conflict with GPIO_Sysfs. Otherwise we'd get a Device Busy
error in GPIO_Sysfs::_export_pin().

libraries/AP_Notify/AP_Notify.cpp

@@ -30,8 +30,8 @@
 #include "VRBoard_LED.h"
 #include "DiscreteRGBLed.h"
 #include "DiscoLED.h"
+#include "Led_Sysfs.h"
 #include <stdio.h>
-#include <AP_HAL_Linux/GPIO.h>
 
 AP_Notify *AP_Notify::_instance;
 
@@ -160,7 +160,7 @@ void AP_Notify::add_backends(void)
     ADD_BACKEND(new ToshibaLED_I2C(TOSHIBA_LED_I2C_BUS_INTERNAL));
 
   #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_NAVIO2
-    ADD_BACKEND(new DiscreteRGBLed(NAVIO2_GPIO_RED, NAVIO2_GPIO_GREEN, NAVIO2_GPIO_BLUE, false));
+    ADD_BACKEND(new Led_Sysfs("rgb_led0", "rgb_led2", "rgb_led1"));
     ADD_BACKEND(new ToshibaLED_I2C(TOSHIBA_LED_I2C_BUS_EXTERNAL));
     ADD_BACKEND(new ToshibaLED_I2C(TOSHIBA_LED_I2C_BUS_INTERNAL));
 

libraries/AP_Notify/Led_Sysfs.cpp

@@ -0,0 +1,50 @@
+/*
+   Copyright (C) 2017 Emlid Ltd. All rights reserved.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <AP_HAL/AP_HAL.h>
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+#include "Led_Sysfs.h"
+
+#include <AP_HAL_Linux/Led_Sysfs.h>
+
+Led_Sysfs::Led_Sysfs(const char *red, const char *green, const char *blue,
+                    uint8_t off_brightness, uint8_t low_brightness, uint8_t medium_brightness, uint8_t high_brightness):
+    RGBLed(off_brightness, high_brightness, medium_brightness, low_brightness),
+    red_led(red),
+    green_led(green),
+    blue_led(blue)
+{
+}
+
+bool Led_Sysfs::hw_init()
+{
+    if (red_led.init() && green_led.init() && blue_led.init()) {
+        return true;
+    }
+
+    return false;
+}
+
+bool Led_Sysfs::hw_set_rgb(uint8_t red, uint8_t green, uint8_t blue)
+{
+    red_led.set_brightness(red);
+    green_led.set_brightness(green);
+    blue_led.set_brightness(blue);
+
+    return true;
+}
+#endif

libraries/AP_Notify/Led_Sysfs.h

@@ -0,0 +1,42 @@
+/*
+  Copyright (C) 2017 Emlid Ltd. All rights reserved.
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#pragma once
+
+#include <AP_HAL/AP_HAL.h>
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+#include <AP_HAL_Linux/Led_Sysfs.h>
+
+#include "RGBLed.h"
+
+class Led_Sysfs: public RGBLed
+{
+public:
+    Led_Sysfs(const char *red, const char *green, const char *blue,
+              uint8_t off_brightness = 0xff , uint8_t low_brightness = 0x00,
+              uint8_t medium_brightness = 0x00, uint8_t high_brightness = 0x00);
+
+protected:
+    bool hw_init(void) override;
+    bool hw_set_rgb(uint8_t r, uint8_t g, uint8_t b) override;
+
+private:
+    Linux::Led_Sysfs red_led;
+    Linux::Led_Sysfs green_led;
+    Linux::Led_Sysfs blue_led;
+};
+#endif