/**
  ******************************************************************************
  * @file    system_stm32u5xx_ns.c
  * @author  MCD Application Team
  * @brief   CMSIS Cortex-M33 Device Peripheral Access Layer System Source File
  *          to be used in non-secure application when the system implements
  *          the TrustZone-M security.
  *
  *   This file provides two functions and one global variable to be called from
  *   user application:
  *      - SystemInit(): This function is called at non-secure startup before
  *                      branch to non-secure main program.
  *                      This call is made inside the "startup_stm32u5xx.s" file.
  *
  *      - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
  *                                  by the user application to setup the SysTick
  *                                  timer or configure other parameters.
  *
  *      - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
  *                                 be called whenever the core clock is changed
  *                                 during program execution.
  *
  *   After each device reset the MSI (4 MHz) is used as system clock source.
  *   Then SystemInit() function is called, in "startup_stm32u5xx.s" file, to
  *   configure the system clock before to branch to main secure program.
  *   Later, when non-secure SystemInit() function is called, in "startup_stm32u5xx.s"
  *   file, the system clock may have been updated from reset value by the main
  *   secure program.
  *
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2021 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */

/** @addtogroup CMSIS
  * @{
  */

/** @addtogroup STM32U5xx_system
  * @{
  */

/** @addtogroup STM32U5xx_System_Private_Includes
  * @{
  */

#include "stm32u5xx.h"


/**
  * @}
  */

/** @addtogroup STM32U5xx_System_Private_TypesDefinitions
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32U5xx_System_Private_Defines
  * @{
  */

#if !defined  (HSE_VALUE)
  #define HSE_VALUE    16000000U /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */

#if !defined  (MSI_VALUE)
  #define MSI_VALUE    4000000U /*!< Value of the Internal oscillator in Hz*/
#endif /* MSI_VALUE */

#if !defined  (HSI_VALUE)
  #define HSI_VALUE    16000000U /*!< Value of the Internal oscillator in Hz*/
#endif /* HSI_VALUE */

/**
  * @}
  */

/** @addtogroup STM32U5xx_System_Private_Macros
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32U5xx_System_Private_Variables
  * @{
  */
  /* The SystemCoreClock variable is updated in three ways:
      1) by calling CMSIS function SystemCoreClockUpdate()
      2) by calling HAL API function HAL_RCC_GetHCLKFreq()
      3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency
         Note: If you use this function to configure the system clock; then there
               is no need to call the 2 first functions listed above, since SystemCoreClock
               variable is updated automatically.
  */
  uint32_t SystemCoreClock = 4000000U;

  const uint8_t  AHBPrescTable[16] = {0U, 0U, 0U, 0U, 0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U, 6U, 7U, 8U, 9U};
  const uint8_t  APBPrescTable[8] =  {0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U};
  const uint32_t MSIRangeTable[16] = {48000000U,24000000U,16000000U,12000000U, 4000000U, 2000000U, 1330000U,\
                                      1000000U, 3072000U, 1536000U,1024000U, 768000U, 400000U, 200000U, 133000U, 100000U};
/**
  * @}
  */

/** @addtogroup STM32U5xx_System_Private_FunctionPrototypes
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32U5xx_System_Private_Functions
  * @{
  */

/**
  * @brief  Setup the microcontroller system.
  * @retval None
  */

void SystemInit(void)
{
  /* Nothing done in non-secure */

  /* Non-secure main application shall call SystemCoreClockUpdate() to update */
  /* the SystemCoreClock variable to insure non-secure application relies on  */
  /* the initial clock reference set by secure application.                   */
}

/**
  * @brief  Update SystemCoreClock variable according to Clock Register Values.
  *         The SystemCoreClock variable contains the core clock (HCLK), it can
  *         be used by the user application to setup the SysTick timer or configure
  *         other parameters.
  *
  * @note   From the non-secure application, the SystemCoreClock value is
  *         retrieved from the secure domain via a Non-Secure Callable function
  *         since the RCC peripheral may be protected with security attributes
  *         that prevent to compute the SystemCoreClock variable from the RCC
  *         peripheral registers.
  *
  * @note   Each time the core clock (HCLK) changes, this function must be called
  *         to update SystemCoreClock variable value. Otherwise, any configuration
  *         based on this variable will be incorrect.
  *
  * @note   - The system frequency computed by this function is not the real
  *           frequency in the chip. It is calculated based on the predefined
  *           constant and the selected clock source:
  *
  *           - If SYSCLK source is MSI, SystemCoreClock will contain the MSI_VALUE(*)
  *
  *           - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(**)
  *
  *           - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(***)
  *
  *           - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(***)
  *             or HSI_VALUE(*) or MSI_VALUE(*) multiplied/divided by the PLL factors.
  *
  *         (*) MSI_VALUE is a constant defined in stm32u5xx_hal.h file (default value
  *             4 MHz) but the real value may vary depending on the variations
  *             in voltage and temperature.
  *
  *         (**) HSI_VALUE is a constant defined in stm32u5xx_hal.h file (default value
  *              16 MHz) but the real value may vary depending on the variations
  *              in voltage and temperature.
  *
  *         (***) HSE_VALUE is a constant defined in stm32u5xx_hal.h file (default value
  *              8 MHz), user has to ensure that HSE_VALUE is same as the real
  *              frequency of the crystal used. Otherwise, this function may
  *              have wrong result.
  *
  *         - The result of this function could be not correct when using fractional
  *           value for HSE crystal.
  *
  * @retval None
  */
void SystemCoreClockUpdate(void)
{
  /* Get the SystemCoreClock value from the secure domain */
  SystemCoreClock = SECURE_SystemCoreClockUpdate();
}


/**
  * @}
  */

/**
  * @}
  */

/**
  * @}
  */

