[DWT] Add API

Signed-off-by: Frederic.Pillon <[email protected]>

Author: fpistm

cores/arduino/board.h

@@ -10,6 +10,7 @@
 #include "clock.h"
 #include "core_callback.h"
 #include "digital_io.h"
+#include "dwt.h"
 #include "hw_config.h"
 #include "low_power.h"
 #include "rtc.h"

cores/arduino/stm32/dwt.c

@@ -0,0 +1,89 @@
+/**
+  ******************************************************************************
+  * @file    dwt.c
+  * @author  Frederic Pillon
+  * @brief   Provide Data Watchpoint and Trace services
+  ******************************************************************************
+  * @attention
+  *
+  * Copyright (c) 2019, STMicroelectronics
+  * All rights reserved.
+  *
+  * This software component is licensed by ST under BSD 3-Clause license,
+  * the "License"; You may not use this file except in compliance with the
+  * License. You may obtain a copy of the License at:
+  *                        opensource.org/licenses/BSD-3-Clause
+  *
+  ******************************************************************************
+  */
+
+#include "dwt.h"
+
+#ifdef DWT_BASE
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+uint32_t dwt_init(void)
+{
+
+  /* Enable use of DWT */
+  if (!(CoreDebug->DEMCR & CoreDebug_DEMCR_TRCENA_Msk)) {
+    CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
+  }
+
+  /* Unlock */
+  dwt_access(true);
+
+  /* Reset the clock cycle counter value */
+  DWT->CYCCNT = 0;
+
+  /* Enable  clock cycle counter */
+  DWT->CTRL |=  DWT_CTRL_CYCCNTENA_Msk;
+
+  /* 3 NO OPERATION instructions */
+  asm volatile(" nop      \n\t"
+               " nop      \n\t"
+               " nop      \n\t");
+
+  /* Check if clock cycle counter has started */
+  return (DWT->CYCCNT) ? 0 : 1;
+}
+
+void dwt_access(bool ena)
+{
+#if (__CORTEX_M == 0x07U)
+  /*
+   * Define DWT LSR mask which is (currentuly) not defined by the CMSIS.
+   * Same as ITM LSR one.
+   */
+#if !defined DWT_LSR_Present_Msk
+#define DWT_LSR_Present_Msk ITM_LSR_Present_Msk
+#endif
+#if !defined DWT_LSR_Access_Msk
+#define DWT_LSR_Access_Msk ITM_LSR_Access_Msk
+#endif
+  uint32_t lsr = DWT->LSR;
+
+  if ((lsr & DWT_LSR_Present_Msk) != 0) {
+    if (ena) {
+      if ((lsr & DWT_LSR_Access_Msk) != 0) { //locked
+        DWT->LAR = 0xC5ACCE55;
+      }
+    } else {
+      if ((lsr & DWT_LSR_Access_Msk) == 0) { //unlocked
+        DWT->LAR = 0;
+      }
+    }
+  }
+#else /* __CORTEX_M */
+  UNUSED(ena);
+#endif /* __CORTEX_M */
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

cores/arduino/stm32/dwt.h

@@ -0,0 +1,61 @@
+/**
+  ******************************************************************************
+  * @file    dwt.h
+  * @author  Frederic Pillon
+  * @brief   Header for dwt.c module
+  ******************************************************************************
+  * @attention
+  *
+  * Copyright (c) 2019, STMicroelectronics
+  * All rights reserved.
+  *
+  * This software component is licensed by ST under BSD 3-Clause license,
+  * the "License"; You may not use this file except in compliance with the
+  * License. You may obtain a copy of the License at:
+  *                        opensource.org/licenses/BSD-3-Clause
+  *
+  ******************************************************************************
+  */
+
+/* Define to prevent recursive inclusion -------------------------------------*/
+#ifndef _DWT_H_
+#define _DWT_H_
+
+#include "stm32_def.h"
+#include <stdbool.h>
+
+#ifdef DWT_BASE
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+uint32_t dwt_init(void);
+void dwt_access(bool ena);
+
+static inline uint32_t dwt_max_sec(void)
+{
+  return (UINT32_MAX / SystemCoreClock);
+};
+
+static inline uint32_t dwt_max_msec(void)
+{
+  return (UINT32_MAX / (SystemCoreClock / 1000));
+};
+
+static inline uint32_t dwt_max_usec(void)
+{
+  return (UINT32_MAX / (SystemCoreClock / 1000000));
+};
+
+static inline uint32_t dwt_getCycles(void)
+{
+  return (DWT->CYCCNT);
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* DWT_BASE */
+#endif /* _DWT_H_ */