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.

4 files changed, 133 insertions, 142 deletions

diff --git a/bsps/arm/include/bsp/clock-armv7m.h b/bsps/arm/include/bsp/clock-armv7m.h
new file mode 100644
index 0000000000..d635fb0c1b
--- /dev/null
+++ b/bsps/arm/include/bsp/clock-armv7m.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2011, 2018 Sebastian Huber.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#ifndef BSP_CLOCK_ARMV7M_H
+#define BSP_CLOCK_ARMV7M_H
+
+#include <rtems/score/armv7m.h>
+#include <rtems/timecounter.h>
+
+#include <bsp.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+#ifdef ARM_MULTILIB_ARCH_V7M
+
+typedef struct {
+  struct timecounter base;
+  uint32_t ticks;
+} ARMV7M_Timecounter;
+
+extern ARMV7M_Timecounter _ARMV7M_TC;
+
+static inline uint32_t _ARMV7M_Clock_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
+}
+
+static uint32_t _ARMV7M_Clock_counter(ARMV7M_Timecounter *tc)
+{
+  volatile ARMV7M_Systick *systick;
+  rtems_interrupt_level level;
+  uint32_t interval;
+  uint32_t counter;
+  uint32_t ticks;
+
+  systick = _ARMV7M_Systick;
+  interval = systick->rvr;
+
+  rtems_interrupt_disable(level);
+  counter = systick->cvr;
+  ticks = tc->ticks;
+
+  if ((systick->csr & ARMV7M_SYSTICK_CSR_COUNTFLAG) != 0) {
+    ticks += interval;
+    tc->ticks = ticks;
+  }
+
+  counter = interval - counter + ticks;
+  rtems_interrupt_enable(level);
+
+  return counter;
+}
+
+#endif /* ARM_MULTILIB_ARCH_V7M */
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* BSP_CLOCK_ARMV7M_H */
diff --git a/bsps/arm/lpc176x/start/system-clocks.c b/bsps/arm/lpc176x/start/system-clocks.c
index 2ec58727eb..6af52be053 100644
--- a/bsps/arm/lpc176x/start/system-clocks.c
+++ b/bsps/arm/lpc176x/start/system-clocks.c
@@ -118,12 +118,3 @@ CPU_Counter_ticks _CPU_Counter_read( void )
 {
   return lpc176x_get_timer1();
 }
-
-inline CPU_Counter_ticks _CPU_Counter_difference(
-  CPU_Counter_ticks second,
-  CPU_Counter_ticks first
-)
-{
-  return second - first;
-}
-
diff --git a/bsps/arm/shared/clock/clock-armv7m.c b/bsps/arm/shared/clock/clock-armv7m.c
index 39cd4efdc7..2efe4c2654 100644
--- a/bsps/arm/shared/clock/clock-armv7m.c
+++ b/bsps/arm/shared/clock/clock-armv7m.c
@@ -1,8 +1,8 @@
 /*
- * Copyright (c) 2011-2012 Sebastian Huber.  All rights reserved.
+ * Copyright (c) 2011, 2018 Sebastian Huber.  All rights reserved.
  *
  *  embedded brains GmbH
- *  Obere Lagerstr. 30
+ *  Dornierstr. 4
  *  82178 Puchheim
  *  Germany
  *  <rtems@embedded-brains.de>
@@ -12,146 +12,97 @@
  * http://www.rtems.org/license/LICENSE.
  */
 
-#include <rtems.h>
-#include <rtems/timecounter.h>
-#include <rtems/score/armv7m.h>
+#include <bsp/clock-armv7m.h>
 
-#include <bsp.h>
+#include <rtems.h>
+#include <rtems/sysinit.h>
 
 #ifdef ARM_MULTILIB_ARCH_V7M
 
 /* This is defined in dev/clock/clockimpl.h */
 static void Clock_isr(void *arg);
 
-typedef struct {
-  rtems_timecounter_simple base;
-  void (*tick)(void);
-  bool countflag;
-} ARMV7M_Timecounter;
-
-static ARMV7M_Timecounter _ARMV7M_TC;
-
-static uint32_t _ARMV7M_TC_systick_get(rtems_timecounter_simple *tc)
-{
-  volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
-
-  return systick->cvr;
-}
-
-static bool _ARMV7M_TC_systick_is_pending(rtems_timecounter_simple *base)
-{
-  ARMV7M_Timecounter *tc = (ARMV7M_Timecounter *) base;
-  rtems_interrupt_level level;
-  bool countflag;
-
-  rtems_interrupt_disable(level);
-
-  countflag = tc->countflag;
-  if (!countflag) {
-    volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
-
-    countflag = ((systick->csr & ARMV7M_SYSTICK_CSR_COUNTFLAG) != 0);
-    tc->countflag = countflag;
-  }
-
-  rtems_interrupt_enable(level);
-
-  return countflag;
-}
-
-static uint32_t _ARMV7M_TC_systick_get_timecount(struct timecounter *tc)
-{
-  return rtems_timecounter_simple_downcounter_get(
-    tc,
-    _ARMV7M_TC_systick_get,
-    _ARMV7M_TC_systick_is_pending
-  );
-}
-
-static void _ARMV7M_TC_systick_at_tick(rtems_timecounter_simple *base)
-{
-  ARMV7M_Timecounter *tc = (ARMV7M_Timecounter *) base;
-  volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
-
-  tc->countflag = false;
-
-  /* Clear COUNTFLAG */
-  systick->csr;
-}
+ARMV7M_Timecounter _ARMV7M_TC;
 
-static void _ARMV7M_TC_systick_tick(void)
+static uint32_t _ARMV7M_TC_get_timecount(struct timecounter *base)
 {
-  rtems_timecounter_simple_downcounter_tick(
-    &_ARMV7M_TC.base,
-    _ARMV7M_TC_systick_get,
-    _ARMV7M_TC_systick_at_tick
-  );
+  return _ARMV7M_Clock_counter((ARMV7M_Timecounter *) base);
 }
 
-static void _ARMV7M_TC_tick(void)
-{
-  (*_ARMV7M_TC.tick)();
-}
-
-static void _ARMV7M_Systick_handler(void)
+static void _ARMV7M_Clock_handler(void)
 {
   _ARMV7M_Interrupt_service_enter();
   Clock_isr(NULL);
   _ARMV7M_Interrupt_service_leave();
 }
 
-static void _ARMV7M_Systick_handler_install(void)
+static void _ARMV7M_Clock_handler_install(void)
 {
   _ARMV7M_Set_exception_priority_and_handler(
     ARMV7M_VECTOR_SYSTICK,
     BSP_ARMV7M_SYSTICK_PRIORITY,
-    _ARMV7M_Systick_handler
+    _ARMV7M_Clock_handler
   );
 }
 
-static void _ARMV7M_Systick_initialize(void)
+static void _ARMV7M_Clock_initialize(void)
 {
-  volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
-  #ifdef BSP_ARMV7M_SYSTICK_FREQUENCY
-    uint64_t freq = BSP_ARMV7M_SYSTICK_FREQUENCY;
-  #else
-    uint64_t freq = ARMV7M_SYSTICK_CALIB_TENMS_GET(systick->calib) * 100ULL;
-  #endif
-  uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
-  uint64_t interval = (freq * us_per_tick) / 1000000ULL;
-
-  systick->rvr = (uint32_t) interval;
-  systick->cvr = 0;
+  volatile ARMV7M_Systick *systick;
+  ARMV7M_Timecounter *tc;
+
+  systick = _ARMV7M_Systick;
+  tc = &_ARMV7M_TC;
+
   systick->csr = ARMV7M_SYSTICK_CSR_ENABLE
     | ARMV7M_SYSTICK_CSR_TICKINT
     | ARMV7M_SYSTICK_CSR_CLKSOURCE;
 
-  _ARMV7M_TC.tick = _ARMV7M_TC_systick_tick;
-  rtems_timecounter_simple_install(
-    &_ARMV7M_TC.base,
-    freq,
-    interval,
-    _ARMV7M_TC_systick_get_timecount
-  );
+  tc->base.tc_get_timecount = _ARMV7M_TC_get_timecount;
+  tc->base.tc_counter_mask = 0xffffffff;
+  tc->base.tc_frequency = _ARMV7M_Clock_frequency();
+  tc->base.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
+  rtems_timecounter_install(&tc->base);
 }
 
-static void _ARMV7M_Systick_cleanup(void)
+static void _ARMV7M_Clock_initialize_early(void)
+{
+  volatile ARMV7M_Systick *systick;
+  uint32_t us_per_tick;
+  uint64_t freq;
+  uint32_t interval;
+
+  systick = _ARMV7M_Systick;
+  us_per_tick = rtems_configuration_get_microseconds_per_tick();
+  freq = _ARMV7M_Clock_frequency();
+
+  interval = (uint32_t) ((freq * us_per_tick) / 1000000);
+
+  systick->rvr = interval;
+  systick->cvr = 0;
+  systick->csr = ARMV7M_SYSTICK_CSR_ENABLE | ARMV7M_SYSTICK_CSR_CLKSOURCE;
+}
+
+RTEMS_SYSINIT_ITEM(
+  _ARMV7M_Clock_initialize_early,
+  RTEMS_SYSINIT_CPU_COUNTER,
+  RTEMS_SYSINIT_ORDER_FIRST
+);
+
+static void _ARMV7M_Clock_cleanup(void)
 {
   volatile ARMV7M_Systick *systick = _ARMV7M_Systick;
 
   systick->csr = 0;
 }
 
-#define Clock_driver_timecounter_tick() _ARMV7M_TC_tick()
-
 #define Clock_driver_support_initialize_hardware() \
-  _ARMV7M_Systick_initialize()
+  _ARMV7M_Clock_initialize()
 
 #define Clock_driver_support_install_isr(isr) \
-  _ARMV7M_Systick_handler_install()
+  _ARMV7M_Clock_handler_install()
 
 #define Clock_driver_support_shutdown_hardware() \
-  _ARMV7M_Systick_cleanup()
+  _ARMV7M_Clock_cleanup()
 
 /* Include shared source clock driver code */
 #include "../../../shared/dev/clock/clockimpl.h"
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
-);