cpukit/include/rtems/btimer.h: Add DOxygen comments

cpukit/include/rtems/btimer.h

@@ -33,20 +33,74 @@
 extern "C" {
 #endif
 
+/**
+ * @defgroup BenchmarkTimer Benchmark Timer Driver Interface
+ *
+ * This module defines the interface for the Benchmark Timer Driver.
+ *
+ * The following methods in this module must be provided by each BSP:
+ *
+ *   - benchmark_timer_initialize
+ *   - benchmark_timer_read
+ *   - benchmark_timer_disable_subtracting_average_overhead
+ *
+ * The units measured are BSP specific but should be at the highest
+ * granularity possible.
+ *
+ * The Benchmark Timer may use the same hardware as the Clock Driver.
+ * No RTEMS Timing Tests will use both drivers at the same time.
+ */
+
+/**
+ * @brief Benchmark Timer Value Type
+ *
+ * This type is used to contain benchmark times. The units are BSP specific.
+ */
 typedef uint32_t benchmark_timer_t;
 
-/* functions */
-
+/**
+ * @brief Initialize the Benchmark Timer
+ *
+ * This method initializes the benchmark timer and resets it to begin
+ * counting.
+ */
 extern void benchmark_timer_initialize( void );
 
+/**
+ * @brief Read the Benchmark Timer
+ *
+ * This method stops the benchmark timer and returns the number of
+ * units that have passed since @a benchmark_timer_initialize was invoked.
+ *
+ * @return This method returns the number of units with the average overhead
+ *          removed. If the value is below the minimum trusted value, zero
+ *          is returned.
+ */
 extern benchmark_timer_t benchmark_timer_read( void );
 
+/**
+ * @brief Benchmark Timer Empty Function
+ *
+ * This method is used to determine loop overhead.
+ */
 extern rtems_status_code benchmark_timer_empty_function( void );
 
+/**
+ * @brief Disable Average Overhead Removal from the Benchmark Timer
+ *
+ * This method places the benchmark timer in a "raw" mode where it
+ * returns the actual number of units which have passed between
+ * calls to @a benchmark_timer_initialize and @a benchmark_timer_read
+ * counting.
+ *
+ * @param[in] find_flag indicates to enable or disable the mode
+ */
 extern void benchmark_timer_disable_subtracting_average_overhead(
   bool find_flag
 );
 
+/**@}*/
+
 #ifdef __cplusplus
 }
 #endif