some doc added

linux/spi/SpiComIF.h

@@ -50,7 +50,7 @@ public:
 
     /**
      * Perform a regular send operation using Linux iotcl. This is public so it can be used
-     * in the user callback if special handling is only necessary for certain commands.
+     * in functions like a user callback if special handling is only necessary for certain commands.
      * @param spiCookie
      * @param sendData
      * @param sendLen

linux/spi/SpiCookie.cpp

@@ -12,18 +12,19 @@ SpiCookie::SpiCookie(address_t spiAddress, std::string spiDev, const size_t maxS
                 SpiCookie(spiAddress, gpio::NO_GPIO, spiDev, maxSize, spiMode, spiSpeed) {
 }
 
-SpiCookie::SpiCookie(address_t spiAddress, gpioId_t chipSelect, std::string spiDev, const size_t maxSize,
-        spi::SpiModes spiMode, uint32_t spiSpeed, spi::send_callback_function_t callback, void *args):
+SpiCookie::SpiCookie(address_t spiAddress, gpioId_t chipSelect, std::string spiDev,
+        const size_t maxSize, spi::SpiModes spiMode, uint32_t spiSpeed,
+        spi::send_callback_function_t callback, void *args):
 		        SpiCookie(spi::SpiComIfModes::CALLBACK, spiAddress, chipSelect, spiDev, maxSize,
 		                spiMode, spiSpeed, callback, args) {
 }
 
 SpiCookie::SpiCookie(spi::SpiComIfModes comIfMode, address_t spiAddress, gpioId_t chipSelect,
         std::string spiDev, const size_t maxSize, spi::SpiModes spiMode, uint32_t spiSpeed,
-        spi::send_callback_function_t callback, void* args): spiAddress(spiAddress),
-                chipSelectPin(chipSelect), spiDevice(spiDev), comIfMode(comIfMode),
-                maxSize(maxSize), spiMode(spiMode), spiSpeed(spiSpeed), sendCallback(callback),
-                callbackArgs(args) {
+        spi::send_callback_function_t callback, void* args):
+                spiAddress(spiAddress), chipSelectPin(chipSelect), spiDevice(spiDev),
+                comIfMode(comIfMode), maxSize(maxSize), spiMode(spiMode), spiSpeed(spiSpeed),
+                sendCallback(callback), callbackArgs(args) {
 }
 
 spi::SpiComIfModes SpiCookie::getComIfMode() const {

linux/spi/SpiCookie.h

@@ -6,6 +6,17 @@
 #include <fsfw_hal/common/gpio/gpioDefinitions.h>
 #include <linux/spi/spidev.h>
 
+/**
+ * @brief   This cookie class is passed to the SPI communication interface
+ * @details
+ * This cookie contains device specific properties like speed and SPI mode or the SPI transfer
+ * struct required by the Linux SPI driver. It also contains a handle to a GPIO interface
+ * to perform slave select switching when necessary.
+ *
+ * The user can specify gpio::NO_GPIO as the GPIO ID or use a custom send callback to meet
+ * special requirements like expander slave select switching (e.g. GPIO or I2C expander)
+ * or special timing related requirements.
+ */
 class SpiCookie: public CookieIF {
 public:
     /**
@@ -32,8 +43,14 @@ public:
      * function here or by using the setter function #setCallbackMode
      */
     SpiCookie(address_t spiAddress, gpioId_t chipSelect, std::string spiDev, const size_t maxSize,
-            spi::SpiModes spiMode, uint32_t spiSpeed, spi::send_callback_function_t callback, void *args);
+            spi::SpiModes spiMode, uint32_t spiSpeed, spi::send_callback_function_t callback,
+            void *args);
 
+    /**
+     * Get the callback function
+     * @param callback
+     * @param args
+     */
     void getCallback(spi::send_callback_function_t* callback, void** args);
 
     address_t getSpiAddress() const;
@@ -48,6 +65,12 @@ public:
     /** Enables changing the SPI mode at run-time */
     void setSpiMode(spi::SpiModes newMode);
 
+    /**
+     * Set the SPI to callback mode and assigns the user supplied callback and an argument
+     * passed to the callback.
+     * @param callback
+     * @param args
+     */
     void setCallbackMode(spi::send_callback_function_t callback, void* args);
 
     /**