* Return         : The clock source used as system clock. The returned value can
*                  be one of the following:
*                       - 0x00: HSI used as system clock
*                       - 0x04: HSE used as system clock
*                       - 0x08: PLL used as system clock
*******************************************************************************/
u8 RCC_GetSYSCLKSource(void)
{
  return ((u8)(RCC->CFGR & CFGR_SWS_Mask));
}

/*******************************************************************************
* Function Name  : RCC_HCLKConfig
* Description    : Configures the AHB clock (HCLK).
* Input          : - RCC_HCLK: defines the AHB clock. This clock is derived
*                    from the system clock (SYSCLK).
*                    This parameter can be one of the following values:
*                       - RCC_SYSCLK_Div1: AHB clock = SYSCLK
*                       - RCC_SYSCLK_Div2: AHB clock = SYSCLK/2
*                       - RCC_SYSCLK_Div4: AHB clock = SYSCLK/4
*                       - RCC_SYSCLK_Div8: AHB clock = SYSCLK/8
*                       - RCC_SYSCLK_Div16: AHB clock = SYSCLK/16
*                       - RCC_SYSCLK_Div64: AHB clock = SYSCLK/64
*                       - RCC_SYSCLK_Div128: AHB clock = SYSCLK/128
*                       - RCC_SYSCLK_Div256: AHB clock = SYSCLK/256
*                       - RCC_SYSCLK_Div512: AHB clock = SYSCLK/512
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_HCLKConfig(u32 RCC_HCLK)
{
  u32 tmpreg = 0;

  /* Check the parameters */
  assert(IS_RCC_HCLK(RCC_HCLK));

  tmpreg = RCC->CFGR;

  /* Clear HPRE[7:4] bits */
  tmpreg &= CFGR_HPRE_Reset_Mask;

  /* Set HPRE[7:4] bits according to RCC_HCLK value */
  tmpreg |= RCC_HCLK;

  /* Store the new value */
  RCC->CFGR = tmpreg;
}

/*******************************************************************************
* Function Name  : RCC_PCLK1Config
* Description    : Configures the Low Speed APB clock (PCLK1).
* Input          : - RCC_PCLK1: defines the APB1 clock. This clock is derived
*                    from the AHB clock (HCLK).
*                    This parameter can be one of the following values:
*                       - RCC_HCLK_Div1: APB1 clock = HCLK
*                       - RCC_HCLK_Div2: APB1 clock = HCLK/2
*                       - RCC_HCLK_Div4: APB1 clock = HCLK/4
*                       - RCC_HCLK_Div8: APB1 clock = HCLK/8
*                       - RCC_HCLK_Div16: APB1 clock = HCLK/16
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_PCLK1Config(u32 RCC_PCLK1)
{
  u32 tmpreg = 0;

  /* Check the parameters */
  assert(IS_RCC_PCLK(RCC_PCLK1));

  tmpreg = RCC->CFGR;

  /* Clear PPRE1[10:8] bits */
  tmpreg &= CFGR_PPRE1_Reset_Mask;

  /* Set PPRE1[10:8] bits according to RCC_PCLK1 value */
  tmpreg |= RCC_PCLK1;

  /* Store the new value */
  RCC->CFGR = tmpreg;
}

/*******************************************************************************
* Function Name  : RCC_PCLK2Config
* Description    : Configures the High Speed APB clock (PCLK2).
* Input          : - RCC_PCLK2: defines the APB2 clock. This clock is derived
*                    from the AHB clock (HCLK).
*                    This parameter can be one of the following values:
*                       - RCC_HCLK_Div1: APB2 clock = HCLK
*                       - RCC_HCLK_Div2: APB2 clock = HCLK/2
*                       - RCC_HCLK_Div4: APB2 clock = HCLK/4
*                       - RCC_HCLK_Div8: APB2 clock = HCLK/8
*                       - RCC_HCLK_Div16: APB2 clock = HCLK/16
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_PCLK2Config(u32 RCC_PCLK2)
{
  u32 tmpreg = 0;

  /* Check the parameters */
  assert(IS_RCC_PCLK(RCC_PCLK2));

  tmpreg = RCC->CFGR;

  /* Clear PPRE2[13:11] bits */
  tmpreg &= CFGR_PPRE2_Reset_Mask;

  /* Set PPRE2[13:11] bits according to RCC_PCLK2 value */
  tmpreg |= RCC_PCLK2 << 3;

  /* Store the new value */
  RCC->CFGR = tmpreg;
}

/*******************************************************************************
* Function Name  : RCC_ITConfig
* Description    : Enables or disables the specified RCC interrupts.
* Input          : - RCC_IT: specifies the RCC interrupt sources to be enabled
*                    or disabled.
*                    This parameter can be any combination of the following values:
*                       - RCC_IT_LSIRDY: LSI ready interrupt
*                       - RCC_IT_LSERDY: LSE ready interrupt
*                       - RCC_IT_HSIRDY: HSI ready interrupt
*                       - RCC_IT_HSERDY: HSE ready interrupt
*                       - RCC_IT_PLLRDY: PLL ready interrupt
*                  - NewState: new state of the specified RCC interrupts.
*                    This parameter can be: ENABLE or DISABLE.
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_ITConfig(u8 RCC_IT, FunctionalState NewState)
{
  /* Check the parameters */
  assert(IS_RCC_IT(RCC_IT));
  assert(IS_FUNCTIONAL_STATE(NewState));

  if (NewState != DISABLE)
  {
    /* Perform Byte access to RCC_CIR[12:8] bits to enable the selected interrupts */
    *(vu8 *) 0x40021009 |= RCC_IT;
  }
  else
  {
    /* Perform Byte access to RCC_CIR[12:8] bits to disable the selected interrupts */
    *(vu8 *) 0x40021009 &= ~(u32)RCC_IT;
  }
}

/*******************************************************************************
* Function Name  : RCC_USBCLKConfig
* Description    : Configures the USB clock (USBCLK).
* Input          : - RCC_USBCLKSource: specifies the USB clock source. This clock
*                    is derived from the PLL output.
*                    This parameter can be one of the following values:
*                       - RCC_USBCLKSource_PLLCLK_1Div5: PLL clock divided by 1,5
*                         selected as USB clock source
*                       - RCC_USBCLKSource_PLLCLK_Div1: PLL clock selected as USB
*                         clock source
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_USBCLKConfig(u32 RCC_USBCLKSource)
{
  /* Check the parameters */
  assert(IS_RCC_USBCLK_SOURCE(RCC_USBCLKSource));

  *(vu32 *) CFGR_USBPRE_BB = RCC_USBCLKSource;
}

/*******************************************************************************
* Function Name  : RCC_ADCCLKConfig
* Description    : Configures the ADC clock (ADCCLK).
* Input          : - RCC_ADCCLK: defines the ADC clock. This clock is derived
*                    from the APB2 clock (PCLK2).
*                    This parameter can be one of the following values:
*                       - RCC_PCLK2_Div2: ADC clock = PCLK2/2
*                       - RCC_PCLK2_Div4: ADC clock = PCLK2/4
*                       - RCC_PCLK2_Div6: ADC clock = PCLK2/6
*                       - RCC_PCLK2_Div8: ADC clock = PCLK2/8
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_ADCCLKConfig(u32 RCC_ADCCLK)
{
  u32 tmpreg = 0;

  /* Check the parameters */
  assert(IS_RCC_ADCCLK(RCC_ADCCLK));

  tmpreg = RCC->CFGR;

  /* Clear ADCPRE[15:14] bits */
  tmpreg &= CFGR_ADCPRE_Reset_Mask;

  /* Set ADCPRE[15:14] bits according to RCC_ADCCLK value */
  tmpreg |= RCC_ADCCLK;

  /* Store the new value */
  RCC->CFGR = tmpreg;
}

/*******************************************************************************
* Function Name  : RCC_LSEConfig
* Description    : Configures the External Low Speed oscillator (LSE).
* Input          : - RCC_LSE: specifies the new state of the LSE.
*                    This parameter can be one of the following values:
*                       - RCC_LSE_OFF: LSE oscillator OFF
*                       - RCC_LSE_ON: LSE oscillator ON
*                       - RCC_LSE_Bypass: LSE oscillator bypassed with external
*                         clock
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_LSEConfig(u32 RCC_LSE)
{
  /* Check the parameters */
  assert(IS_RCC_LSE(RCC_LSE));

  /* Reset LSEON and LSEBYP bits before configuring the LSE ------------------*/
  /* Reset LSEON bit */
  *(vu8 *) BDCR_BASE = RCC_LSE_OFF;

  /* Reset LSEBYP bit */
  *(vu8 *) BDCR_BASE = RCC_LSE_OFF;

  /* Configure LSE (RCC_LSE_OFF is already covered by the code section above) */
  switch(RCC_LSE)
  {
    case RCC_LSE_ON:
      /* Set LSEON bit */
      *(vu8 *) BDCR_BASE = RCC_LSE_ON;
      break;
      
    case RCC_LSE_Bypass:
      /* Set LSEBYP and LSEON bits */
      *(vu8 *) BDCR_BASE = RCC_LSE_Bypass | RCC_LSE_ON;
      break;            
      
    default:
      break;      
  }
}

/*******************************************************************************
* Function Name  : RCC_LSICmd
* Description    : Enables or disables the Internal Low Speed oscillator (LSI).
*                  LSI can not be disabled if the IWDG is running.
* Input          : - NewState: new state of the LSI.
*                    This parameter can be: ENABLE or DISABLE.
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_LSICmd(FunctionalState NewState)
{
  /* Check the parameters */
  assert(IS_FUNCTIONAL_STATE(NewState));

  *(vu32 *) CSR_LSION_BB = (u32)NewState;
}

/*******************************************************************************
* Function Name  : RCC_RTCCLKConfig
* Description    : Configures the RTC clock (RTCCLK).
*                  Once the RTC clock is selected it can抰 be changed unless the
*                  Backup domain is reset.
* Input          : - RCC_RTCCLKSource: specifies the RTC clock source.
*                    This parameter can be one of the following values:
*                       - RCC_RTCCLKSource_LSE: LSE selected as RTC clock
*                       - RCC_RTCCLKSource_LSI: LSI selected as RTC clock
*                       - RCC_RTCCLKSource_HSE_Div128: HSE clock divided by 128
*                         selected as RTC clock
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_RTCCLKConfig(u32 RCC_RTCCLKSource)
{
  /* Check the parameters */
  assert(IS_RCC_RTCCLK_SOURCE(RCC_RTCCLKSource));

  /* Select the RTC clock source */
  RCC->BDCR |= RCC_RTCCLKSource;
}

/*******************************************************************************
* Function Name  : RCC_RTCCLKCmd
* Description    : Enables or disables the RTC clock.
*                  This function must be used only after the RTC clock was
*                  selected using the RCC_RTCCLKConfig function.
* Input          : - NewState: new state of the RTC clock.
*                    This parameter can be: ENABLE or DISABLE.
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_RTCCLKCmd(FunctionalState NewState)
{
  /* Check the parameters */
  assert(IS_FUNCTIONAL_STATE(NewState));

  *(vu32 *) BDCR_RTCEN_BB = (u32)NewState;
}

/*******************************************************************************
* Function Name  : RCC_GetClocksFreq
* Description    : Returns the frequencies of different on chip clocks.
* Input          : - RCC_Clocks: pointer to a RCC_ClocksTypeDef structure which
*                    will hold the clocks frequencies.
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_GetClocksFreq(RCC_ClocksTypeDef* RCC_Clocks)
{
  u32 tmp = 0, pllmull = 0, pllsource = 0, presc = 0;

  /* Get SYSCLK source -------------------------------------------------------*/
  tmp = RCC->CFGR & CFGR_SWS_Mask;

  switch (tmp)
  {
    case 0x00:  /* HSI used as system clock */
      RCC_Clocks->SYSCLK_Frequency = HSI_Value;
      break;

    case 0x04:  /* HSE used as system clock */
      RCC_Clocks->SYSCLK_Frequency = HSE_Value;
      break;

    case 0x08:  /* PLL used as system clock */
      /* Get PLL clock source and multiplication factor ----------------------*/
      pllmull = RCC->CFGR & CFGR_PLLMull_Mask;
      pllmull = ( pllmull >> 18) + 2;

      pllsource = RCC->CFGR & CFGR_PLLSRC_Mask;

      if (pllsource == 0x00)
      {/* HSI oscillator clock divided by 2 selected as PLL clock entry */
        RCC_Clocks->SYSCLK_Frequency = (HSI_Value >> 1) * pllmull;
      }
      else
      {/* HSE selected as PLL clock entry */

        if ((RCC->CFGR & CFGR_PLLXTPRE_Mask) != (u32)RESET)
        {/* HSE oscillator clock divided by 2 */

          RCC_Clocks->SYSCLK_Frequency = (HSE_Value >> 1) * pllmull;
        }
        else
        {
          RCC_Clocks->SYSCLK_Frequency = HSE_Value * pllmull;
        }
      }
      break;

    default:
      RCC_Clocks->SYSCLK_Frequency = HSI_Value;
      break;
  }

  /* Compute HCLK, PCLK1, PCLK2 and ADCCLK clocks frequencies ----------------*/
  /* Get HCLK prescaler */
  tmp = RCC->CFGR & CFGR_HPRE_Set_Mask;
  tmp = tmp >> 4;
  presc = APBAHBPrescTable[tmp];

  /* HCLK clock frequency */
  RCC_Clocks->HCLK_Frequency = RCC_Clocks->SYSCLK_Frequency >> presc;

  /* Get PCLK1 prescaler */
  tmp = RCC->CFGR & CFGR_PPRE1_Set_Mask;