[DeviceDrivers] Add more API.

1. Use float type for clock_cpu_getres() return value;
2. Add clock_cpu_microsecond/millisecond APIs.

2 files changed, 40 insertions, 3 deletions

diff --git a/components/drivers/cputime/cputime.c b/components/drivers/cputime/cputime.c
index a607aeefa1..20f41b6dac 100644
--- a/components/drivers/cputime/cputime.c
+++ b/components/drivers/cputime/cputime.c
@@ -30,8 +30,10 @@ static const struct rt_clock_cputime_ops *_cputime_ops  = RT_NULL;
 /**
  * The clock_cpu_getres() function shall return the resolution of CPU time, the 
  * number of nanosecond per tick.
+ *
+ * @return the number of nanosecond per tick
  */
-uint32_t clock_cpu_getres(void)
+float clock_cpu_getres(void)
 {
     if (_cputime_ops)
         return _cputime_ops->cputime_getres();
@@ -42,6 +44,8 @@ uint32_t clock_cpu_getres(void)
 
 /**
  * The clock_cpu_gettime() function shall return the current value of cpu time tick.
+ *
+ * @return the cpu tick
  */
 uint32_t clock_cpu_gettime(void)
 {
@@ -53,6 +57,36 @@ uint32_t clock_cpu_gettime(void)
 }
 
 /**
+ * The clock_cpu_microsecond() fucntion shall return the microsecond according to 
+ * cpu_tick parameter.
+ *
+ * @param cpu_tick the cpu tick
+ *
+ * @return the microsecond
+ */
+uint32_t clock_cpu_microsecond(uint32_t cpu_tick)
+{
+    float unit = clock_cpu_getres();
+
+    return (cpu_tick * unit) / 1000;
+}
+
+/**
+ * The clock_cpu_microsecond() fucntion shall return the millisecond according to 
+ * cpu_tick parameter.
+ *
+ * @param cpu_tick the cpu tick
+ *
+ * @return the millisecond
+ */
+uint32_t clock_cpu_millisecond(uint32_t cpu_tick)
+{
+    float unit = clock_cpu_getres();
+
+    return (cpu_tick * unit) / (1000 * 1000);
+}
+
+/**
  * The clock_cpu_seops() function shall set the ops of cpu time.
  * 
  * @return always return 0.
diff --git a/components/drivers/cputime/cputime_cortexm.c b/components/drivers/cputime/cputime_cortexm.c
index 7db27b4b98..f576df785f 100644
--- a/components/drivers/cputime/cputime_cortexm.c
+++ b/components/drivers/cputime/cputime_cortexm.c
@@ -30,9 +30,12 @@
 
 /* Use Cycle counter of Data Watchpoint and Trace Register for CPU time */
 
-static uint32_t cortexm_cputime_getres(void)
+static float cortexm_cputime_getres(void)
 {
-    return (1000 * 1000 * 1000)/SystemCoreClock;
+    float ret = 1000 * 1000 * 1000;
+    
+    ret = ret / SystemCoreClock;
+    return ret;
 }
 
 static uint32_t cortexm_cputime_gettime(void)