Add _CPU_Counter_frequency()

Add rtems_counter_frequency() API function.  Use it to initialize the
counter value converter via the new system initialization step
(RTEMS_SYSINIT_CPU_COUNTER).  This decouples the counter implementation
and the counter converter.  It avoids an unnecessary pull in of the
64-bit integer division from libgcc.

Update #3456.

3 files changed, 24 insertions, 15 deletions

diff --git a/bsps/arm/shared/clock/clock-a9mpcore.c b/bsps/arm/shared/clock/clock-a9mpcore.c
index f9b2d08c9b..a68a627c5b 100644
--- a/bsps/arm/shared/clock/clock-a9mpcore.c
+++ b/bsps/arm/shared/clock/clock-a9mpcore.c
@@ -157,6 +157,11 @@ static void a9mpcore_clock_initialize(void)
   rtems_timecounter_install(&a9mpcore_tc);
 }
 
+uint32_t _CPU_Counter_frequency(void)
+{
+  return a9mpcore_clock_periphclk();
+}
+
 CPU_Counter_ticks _CPU_Counter_read(void)
 {
   volatile a9mpcore_gt *gt = A9MPCORE_GT;
diff --git a/bsps/arm/shared/clock/clock-generic-timer.c b/bsps/arm/shared/clock/clock-generic-timer.c
index 8a992d44f4..2cb85003e1 100644
--- a/bsps/arm/shared/clock/clock-generic-timer.c
+++ b/bsps/arm/shared/clock/clock-generic-timer.c
@@ -166,6 +166,11 @@ static void arm_gt_clock_initialize(void)
   rtems_timecounter_install(tc);
 }
 
+uint32_t _CPU_Counter_frequency(void)
+{
+  return arm_gt_clock_instance.interval;
+}
+
 CPU_Counter_ticks _CPU_Counter_read(void)
 {
   return (uint32_t) arm_gt_clock_get_count();
@@ -179,14 +184,12 @@ static void arm_gt_clock_early_init(void)
     &arm_gt_clock_instance.interval,
     &arm_gt_clock_instance.irq
   );
-
-  rtems_counter_initialize_converter(arm_gt_clock_instance.interval);
 }
 
 RTEMS_SYSINIT_ITEM(
   arm_gt_clock_early_init,
-  RTEMS_SYSINIT_BSP_START,
-  RTEMS_SYSINIT_ORDER_LAST
+  RTEMS_SYSINIT_CPU_COUNTER,
+  RTEMS_SYSINIT_ORDER_FIRST
 );
 
 #define Clock_driver_support_at_tick() \
diff --git a/bsps/arm/shared/cpucounter/cpucounter-armv7m.c b/bsps/arm/shared/cpucounter/cpucounter-armv7m.c
index 7d2581879f..b7593602ed 100644
--- a/bsps/arm/shared/cpucounter/cpucounter-armv7m.c
+++ b/bsps/arm/shared/cpucounter/cpucounter-armv7m.c
@@ -19,6 +19,16 @@
 #include <bsp.h>
 #include <bsp/fatal.h>
 
+uint32_t _CPU_Counter_frequency(void)
+{
+#ifdef BSP_ARMV7M_SYSTICK_FREQUENCY
+  return = BSP_ARMV7M_SYSTICK_FREQUENCY;
+#else
+  volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
+  return ARMV7M_SYSTICK_CALIB_TENMS_GET(systick->calib) * 100;
+#endif
+}
+
 CPU_Counter_ticks _CPU_Counter_read(void)
 {
   volatile ARMV7M_DWT *dwt = _ARMV7M_DWT;
@@ -32,22 +42,13 @@ static void armv7m_cpu_counter_initialize(void)
 
   cyccnt_enabled = _ARMV7M_DWT_Enable_CYCCNT();
 
-  if (cyccnt_enabled) {
-    #ifdef BSP_ARMV7M_SYSTICK_FREQUENCY
-      uint64_t freq = BSP_ARMV7M_SYSTICK_FREQUENCY;
-    #else
-      volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
-      uint64_t freq = ARMV7M_SYSTICK_CALIB_TENMS_GET(systick->calib) * 100ULL;
-    #endif
-
-    rtems_counter_initialize_converter(freq);
-  } else {
+  if (!cyccnt_enabled) {
     bsp_fatal(BSP_ARM_ARMV7M_CPU_COUNTER_INIT);
   }
 }
 
 RTEMS_SYSINIT_ITEM(
   armv7m_cpu_counter_initialize,
-  RTEMS_SYSINIT_BSP_START,
+  RTEMS_SYSINIT_CPU_COUNTER,
   RTEMS_SYSINIT_ORDER_FIRST
 );