/**
  ******************************************************************************
  * @file    system_stm32l0xx.c
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    22-April-2014
  * @brief   CMSIS Cortex-M0+ Device Peripheral Access Layer System Source File.
  *
  *   This file provides two functions and one global variable to be called from 
  *   user application:
  *      - SystemInit(): This function is called at startup just after reset and 
  *                      before branch to main program. This call is made inside
  *                      the "startup_stm32l0xx.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.
  *
  * This file configures the system clock as follows:
  *-----------------------------------------------------------------------------
  * System clock source                | 1- PLL_HSE_EXTC        | 3- PLL_HSI
  *                                    | (external 8 MHz clock) | (internal 16 MHz)
  *                                    | 2- PLL_HSE_XTAL        |
  *                                    | (external 8 MHz xtal)  |
  *-----------------------------------------------------------------------------
  * SYSCLK(MHz)                        | 32                     | 32
  *-----------------------------------------------------------------------------
  * AHBCLK (MHz)                       | 32                     | 32
  *-----------------------------------------------------------------------------
  * APB1CLK (MHz)                      | 32                     | 32
  *-----------------------------------------------------------------------------
  * APB2CLK (MHz)                      | 32                     | 32
  *-----------------------------------------------------------------------------
  * USB capable (48 MHz precise clock) | YES                    | YES
  *-----------------------------------------------------------------------------  
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2014 STMicroelectronics</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */

/** @addtogroup CMSIS
  * @{
  */

/** @addtogroup stm32l0xx_system
  * @{
  */  
  
/** @addtogroup STM32L0xx_System_Private_Includes
  * @{
  */

#include "stm32l0xx.h"

#if !defined  (HSE_VALUE) 
  #define HSE_VALUE    ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */

#if !defined  (MSI_VALUE)
  #define MSI_VALUE    ((uint32_t)2000000) /*!< Value of the Internal oscillator in Hz*/
#endif /* MSI_VALUE */
   
#if !defined  (HSI_VALUE)
  #define HSI_VALUE    ((uint32_t)16000000) /*!< Value of the Internal oscillator in Hz*/
#endif /* HSI_VALUE */


/**
  * @}
  */

/** @addtogroup STM32L0xx_System_Private_TypesDefinitions
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32L0xx_System_Private_Defines
  * @{
  */
/************************* Miscellaneous Configuration ************************/

/*!< Uncomment the following line if you need to relocate your vector Table in
     Internal SRAM. */
/* #define VECT_TAB_SRAM */
#define VECT_TAB_OFFSET  0x00 /*!< Vector Table base offset field. 
                                   This value must be a multiple of 0x200. */
/******************************************************************************/
/**
  * @}
  */

/** @addtogroup STM32L0xx_System_Private_Macros
  * @{
  */

/* Select the clock sources (other than HSI) to start with (0=OFF, 1=ON) */
#define USE_PLL_HSE_EXTC (1) /* Use external clock */
#define USE_PLL_HSE_XTAL (1) /* Use external xtal */

/**
  * @}
  */

/** @addtogroup STM32L0xx_System_Private_Variables
  * @{
  */
  /* This 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 = 32000000;

const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
const uint8_t PLLMulTable[9] = {3, 4, 6, 8, 12, 16, 24, 32, 48};
const uint8_t APBAHBPrescTable[16] = {0, 0, 0, 0, 1, 2, 3, 4, 1, 2, 3, 4, 6, 7, 8, 9};
const uint32_t MSIRangeTable[7] = {64000, 128000, 256000, 512000, 1000000, 2000000, 4000000};

/**
  * @}
  */

/** @addtogroup STM32L0xx_System_Private_FunctionPrototypes
  * @{
  */

#if (USE_PLL_HSE_XTAL != 0) || (USE_PLL_HSE_EXTC != 0)
uint8_t SetSysClock_PLL_HSE(uint8_t bypass);
#endif

uint8_t SetSysClock_PLL_HSI(void);

/**
  * @}
  */

/** @addtogroup STM32L0xx_System_Private_Functions
  * @{
  */

/**
  * @brief  Setup the microcontroller system.
  * @param  None
  * @retval None
  */
void SystemInit (void)
{    
/*!< Set MSION bit */
  RCC->CR |= (uint32_t)0x00000100;

  /*!< Reset SW[1:0], HPRE[3:0], PPRE1[2:0], PPRE2[2:0], MCOSEL[2:0] and MCOPRE[2:0] bits */
  RCC->CFGR &= (uint32_t) 0x88FF400C;
 
  /*!< Reset HSION, HSIDIVEN, HSEON, CSSON and PLLON bits */
  RCC->CR &= (uint32_t)0xFEF6FFF6;
  
  /*!< Reset HSI48ON  bit */
  RCC->CRRCR &= (uint32_t)0xFFFFFFFE;
  
  /*!< Reset HSEBYP bit */
  RCC->CR &= (uint32_t)0xFFFBFFFF;

  /*!< Reset PLLSRC, PLLMUL[3:0] and PLLDIV[1:0] bits */
  RCC->CFGR &= (uint32_t)0xFF02FFFF;

  /*!< Disable all interrupts */
  RCC->CIER = 0x00000000;
  
  /* Configure the Vector Table location add offset address ------------------*/
#ifdef VECT_TAB_SRAM
  SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
#else
  SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
#endif

  /* Configure the Cube driver */
  HAL_Init();

  /* Configure the System clock source, PLL Multiplier and Divider factors,
     AHB/APBx prescalers and Flash settings */
  SetSysClock();
}

/**
  * @brief  Update SystemCoreClock 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   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 as defined by the MSI range.
  *                                   
  *           - 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(*) multiplied/divided by the PLL factors.
  *         
  *         (*) HSI_VALUE is a constant defined in stm32l0xx_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 stm32l0xx_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.
  * @param  None
  * @retval None
  */
void SystemCoreClockUpdate (void)
{
  uint32_t tmp = 0, pllmul = 0, plldiv = 0, pllsource = 0, msirange = 0;

  /* Get SYSCLK source -------------------------------------------------------*/
  tmp = RCC->CFGR & RCC_CFGR_SWS;
  
  switch (tmp)
  {
    case 0x00:  /* MSI used as system clock */
      SystemCoreClock = ((1 <<((RCC->ICSCR & RCC_ICSCR_MSIRANGE)>>13 ))* 64000);
      break;
    case 0x04:  /* HSI used as system clock */
      SystemCoreClock = HSI_VALUE;
      break;
    case 0x08:  /* HSE used as system clock */
      SystemCoreClock = HSE_VALUE;
      break;
    case 0x0C:  /* PLL used as system clock */
      /* Get PLL clock source and multiplication factor ----------------------*/
      pllmul = RCC->CFGR & RCC_CFGR_PLLMUL;
      plldiv = RCC->CFGR & RCC_CFGR_PLLDIV;
      pllmul = PLLMulTable[(pllmul >> 18)];
      plldiv = (plldiv >> 22) + 1;
      
      pllsource = RCC->CFGR & RCC_CFGR_PLLSRC;

      if (pllsource == 0x00)
      {
        /* HSI oscillator clock selected as PLL clock entry */
        SystemCoreClock = (((HSI_VALUE) * pllmul) / plldiv);
      }
      else
      {
        /* HSE selected as PLL clock entry */
        SystemCoreClock = (((HSE_VALUE) * pllmul) / plldiv);
      }
      break;
    default: /* MSI used as system clock */
      msirange = (RCC->ICSCR & RCC_ICSCR_MSIRANGE) >> 13;
      SystemCoreClock = (32768 * (1 << (msirange + 1)));
      break;
  }
  /* Compute HCLK clock frequency --------------------------------------------*/
  /* Get HCLK prescaler */
  tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];
  /* HCLK clock frequency */
  SystemCoreClock >>= tmp;
}

/**
  * @brief  Configures the System clock source, PLL Multiplier and Divider factors,
  *               AHB/APBx prescalers and Flash settings
  * @note   This function should be called only once the RCC clock configuration  
  *         is reset to the default reset state (done in SystemInit() function).             
  * @param  None
  * @retval None
  */
void SetSysClock(void)
{
  /* 1- Try to start with HSE and external clock */
#if USE_PLL_HSE_EXTC != 0
  if (SetSysClock_PLL_HSE(1) == 0)
#endif
  {
    /* 2- If fail try to start with HSE and external xtal */
    #if USE_PLL_HSE_XTAL != 0
    if (SetSysClock_PLL_HSE(0) == 0)
    #endif
    {
      /* 3- If fail start with HSI clock */
      if (SetSysClock_PLL_HSI() == 0)
      {
        while(1)
        {
          // [TODO] Put something here to tell the user that a problem occured...
        }
      }
    }
  }
  
  /* Output clock on MCO1 pin(PA8) for debugging purpose */
  //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_SYSCLK, RCC_MCODIV_1);
  //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI48, RCC_MCODIV_1);
}

#if (USE_PLL_HSE_XTAL != 0) || (USE_PLL_HSE_EXTC != 0)
/******************************************************************************/
/*            PLL (clocked by HSE) used as System clock source                */
/******************************************************************************/
uint8_t SetSysClock_PLL_HSE(uint8_t bypass)
{
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_OscInitTypeDef RCC_OscInitStruct;

  /* Used to gain time after DeepSleep in case HSI is used */
  if (__HAL_RCC_GET_FLAG(RCC_FLAG_HSIRDY) != RESET)
  {
    return 0;
  }
  
  /* The voltage scaling allows optimizing the power consumption when the device is 
     clocked below the maximum system frequency, to update the voltage scaling value 
     regarding system frequency refer to product datasheet. */
  __PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
  
  /* Enable HSE and HSI48 oscillators and activate PLL with HSE as source */
  RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSE | RCC_OSCILLATORTYPE_HSI | RCC_OSCILLATORTYPE_HSI48;
  if (bypass == 0)
  {
    RCC_OscInitStruct.HSEState          = RCC_HSE_ON; /* External 8 MHz xtal on OSC_IN/OSC_OUT */
  }
  else
  {
    RCC_OscInitStruct.HSEState          = RCC_HSE_BYPASS; /* External 8 MHz clock on OSC_IN */
  }
  RCC_OscInitStruct.HSIState            = RCC_HSI_OFF;
  RCC_OscInitStruct.HSI48State          = RCC_HSI48_ON; /* For USB and RNG clock */
  // PLLCLK = (8 MHz * 8)/2 = 32 MHz
  RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL          = RCC_PLLMUL_8;
  RCC_OscInitStruct.PLL.PLLDIV          = RCC_PLLDIV_2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    return 0; // FAIL
  }
 
  /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
  RCC_ClkInitStruct.ClockType      = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
  RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK; // 32 MHz
  RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;         // 32 MHz
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    return 0; // FAIL
  }

  /* Output clock on MCO1 pin(PA8) for debugging purpose */
  //if (bypass == 0)
  //  HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSE, RCC_MCODIV_2); // 4 MHz
  //else
  //  HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSE, RCC_MCODIV_1); // 8 MHz
  
  return 1; // OK
}
#endif

/******************************************************************************/
/*            PLL (clocked by HSI) used as System clock source                */
/******************************************************************************/
uint8_t SetSysClock_PLL_HSI(void)
{
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_OscInitTypeDef RCC_OscInitStruct;

  /* The voltage scaling allows optimizing the power consumption when the device is 
     clocked below the maximum system frequency, to update the voltage scaling value 
     regarding system frequency refer to product datasheet. */
  __PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 
  /* Enable HSI and HSI48 oscillators and activate PLL with HSI as source */
  RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSI | RCC_OSCILLATORTYPE_HSE | RCC_OSCILLATORTYPE_HSI48;
  RCC_OscInitStruct.HSEState            = RCC_HSE_OFF;
  RCC_OscInitStruct.HSIState            = RCC_HSI_ON;
  RCC_OscInitStruct.HSI48State          = RCC_HSI48_ON; /* For USB and RNG clock */
  // PLLCLK = (16 MHz * 4)/2 = 32 MHz
  RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLMUL          = RCC_PLLMUL_4;
  RCC_OscInitStruct.PLL.PLLDIV          = RCC_PLLDIV_2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    return 0; // FAIL
  }
 
  /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
  RCC_ClkInitStruct.ClockType      = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
  RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK; // 32 MHz
  RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;         // 32 MHz
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;           // 32 MHz
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    return 0; // FAIL
  }

  /* Output clock on MCO1 pin(PA8) for debugging purpose */
  //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI, RCC_MCODIV_1); // 16 MHz
  
  return 1; // OK
}

/* Used for the different timeouts in the HAL */
void SysTick_Handler(void)
{
  HAL_IncTick();
}

/**
  * @}
  */

/**
  * @}
  */

/**
  * @}
  */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
