arm: Simplify CPU counter support

Use the standard ARMv7-M systick module for the ARMv7-M CPU counter
instead of DWT counter since the DWT counter is affected by power saving
states.

Use an inline function for _CPU_Counter_difference() for all ARM BSPs.

Update #3456.

1 files changed, 4 insertions, 33 deletions

diff --git a/bsps/arm/shared/cpucounter/cpucounter-armv7m.c b/bsps/arm/shared/cpucounter/cpucounter-armv7m.c
index b7593602ed..bb7cdc441b 100644
--- a/bsps/arm/shared/cpucounter/cpucounter-armv7m.c
+++ b/bsps/arm/shared/cpucounter/cpucounter-armv7m.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 embedded brains GmbH.  All rights reserved.
+ * Copyright (c) 2016, 2018 embedded brains GmbH.  All rights reserved.
  *
  *  embedded brains GmbH
  *  Dornierstr. 4
@@ -12,43 +12,14 @@
  * http://www.rtems.org/license/LICENSE.
  */
 
-#include <rtems/score/armv7m.h>
-#include <rtems/counter.h>
-#include <rtems/sysinit.h>
-
-#include <bsp.h>
-#include <bsp/fatal.h>
+#include <bsp/clock-armv7m.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
+  return _ARMV7M_Clock_frequency();
 }
 
 CPU_Counter_ticks _CPU_Counter_read(void)
 {
-  volatile ARMV7M_DWT *dwt = _ARMV7M_DWT;
-
-  return dwt->cyccnt;
-}
-
-static void armv7m_cpu_counter_initialize(void)
-{
-  bool cyccnt_enabled;
-
-  cyccnt_enabled = _ARMV7M_DWT_Enable_CYCCNT();
-
-  if (!cyccnt_enabled) {
-    bsp_fatal(BSP_ARM_ARMV7M_CPU_COUNTER_INIT);
-  }
+  return _ARMV7M_Clock_counter(&_ARMV7M_TC);
 }
-
-RTEMS_SYSINIT_ITEM(
-  armv7m_cpu_counter_initialize,
-  RTEMS_SYSINIT_CPU_COUNTER,
-  RTEMS_SYSINIT_ORDER_FIRST
-);