led: Add on board LED support

This patch adds support for using on board LED through sysfs.
Commonly available LED parameters are supported.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa.h

@@ -34,6 +34,7 @@ extern "C" {
 #include "mraa/i2c.h"
 #include "mraa/uart.h"
 #include "mraa/uart_ow.h"
+#include "mraa/led.h"
 
 #ifdef __cplusplus
 }

api/mraa.hpp

@@ -31,3 +31,4 @@
 #include "mraa/i2c.hpp"
 #include "mraa/spi.hpp"
 #include "mraa/uart.hpp"
+#include "mraa/led.hpp"

api/mraa/led.h

@@ -0,0 +1,111 @@
+/*
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ * Copyright (c) 2017 Linaro Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+/**
+ * @file
+ * @brief LED module
+ *
+ * LED is the Light Emitting Diode interface to libmraa. It is used to
+ * access the on board LED's via sysfs.
+ *
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "common.h"
+#include <stdio.h>
+
+/**
+ * Opaque pointer definition to the internal struct _led
+ */
+typedef struct _led* mraa_led_context;
+
+/**
+ * Initialise led_context, based on led function name.
+ * The structure of LED entry in sysfs is "devicename:colour:function"
+ * This api expects only one unique LED identifier which would be
+ * "function" name most often. For instance, `mraa_led_init("user4");`
+ *
+ *  @param led Name of the LED
+ *  @returns LED context or NULL
+ */
+mraa_led_context mraa_led_init(const char* led);
+
+/**
+ * Set LED brightness
+ *
+ *  @param dev LED context
+ *  @param value Integer value to write
+ *  @returns Result of operation
+ */
+mraa_result_t mraa_led_set_brightness(mraa_led_context dev, int value);
+
+/**
+ * Read LED brightness
+ *
+ *  @param dev LED context
+ *  @returns Brightness value
+ */
+int mraa_led_read_brightness(mraa_led_context dev);
+
+/**
+ * Read LED maximum brightness
+ *
+ *  @param dev LED context
+ *  @returns Maximum brightness value
+ */
+int mraa_led_read_max_brightness(mraa_led_context dev);
+
+/**
+ * Set LED trigger
+ *
+ *  @param dev LED context
+ *  @param trigger Type of trigger to set
+ *  @returns Result of operation
+ */
+mraa_result_t mraa_led_set_trigger(mraa_led_context dev, const char* trigger);
+
+/**
+ * Clear active LED trigger
+ *
+ *  @param dev LED context
+ *  @returns Result of operation
+ */
+mraa_result_t mraa_led_clear_trigger(mraa_led_context dev);
+
+/**
+ * Close LED file descriptors and free the context memory
+ *
+ *  @param dev LED context
+ *  @returns Result of operation
+ */
+mraa_result_t mraa_led_close(mraa_led_context dev);
+
+#ifdef __cplusplus
+}
+#endif

api/mraa/led.hpp

@@ -0,0 +1,139 @@
+/*
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ * Copyright (c) 2017 Linaro Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#include "led.h"
+#include "types.hpp"
+#include <stdexcept>
+
+namespace mraa
+{
+
+/**
+ * @brief API to Light Emitting Diode
+ *
+ * This file defines the LED interface for libmraa
+ *
+ */
+class Led
+{
+  public:
+    /**
+     * Instantiates an LED object
+     *
+     * @param led LED fuction name to use
+     */
+    Led(const char* led)
+    {
+        m_led = mraa_led_init(led);
+
+        if (m_led == NULL) {
+            throw std::invalid_argument("Invalid LED name specified");
+        }
+    }
+
+    /**
+     * LED Constructor, takes a pointer to a LED context and initialises
+     * the LED class
+     *
+     * @param led_context void * to LED context
+     */
+    Led(void* led_context)
+    {
+        m_led = (mraa_led_context) led_context;
+        if (m_led == NULL) {
+            throw std::invalid_argument("Invalid LED name specified");
+        }
+    }
+
+    /**
+     * LED object destructor
+     */
+    ~Led()
+    {
+        mraa_led_close(m_led);
+    }
+
+    /**
+     * Set LED brightness value
+     *
+     * @param value Value to set LED brightness
+     * @return Result of operation
+     */
+    Result
+    setBrightness(int value)
+    {
+        return (Result) mraa_led_set_brightness(m_led, value);
+    }
+
+    /**
+     * Read LED brightness value
+     *
+     * @return LED brightness value
+     */
+    int
+    readBrightness()
+    {
+        return mraa_led_read_brightness(m_led);
+    }
+
+    /**
+     * Read LED maximum brightness value
+     *
+     * @return LED max brightness value
+     */
+    int
+    readMaxBrightness()
+    {
+        return mraa_led_read_max_brightness(m_led);
+    }
+
+    /**
+     * Set LED trigger
+     *
+     * @param trigger Type of trigger to set
+     * @return Result of operation
+     */
+    Result
+    trigger(const char* trigger)
+    {
+        return (Result) mraa_led_set_trigger(m_led, trigger);
+    }
+
+    /**
+     * Clear active LED trigger
+     *
+     * @return Result of operation
+     */
+    Result
+    clearTrigger()
+    {
+        return (Result) mraa_led_clear_trigger(m_led);
+    }
+
+  private:
+    mraa_led_context m_led;
+};
+}