/**
  ******************************************************************************
  * @file    stm32l1xx_rcc.c
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    31-December-2010
  * @brief   This file provides firmware functions to manage the following 
  *          functionalities of the Reset and clock control (RCC) peripheral:           
  *           - Internal/external clocks, PLL, CSS and MCO configuration
  *           - System, AHB and APB busses clocks configuration
  *           - Peripheral clocks configuration
  *           - Interrupts and flags management
  *
  *  @verbatim
  *               
  *          ===================================================================
  *                               RCC specific features
  *          ===================================================================
  *    
  *          After reset the device is running from MSI (2 MHz) with Flash 0 WS, 
  *          all peripherals are off except internal SRAM, Flash and JTAG.
  *           - There is no prescaler on High speed (AHB) and Low speed (APB) busses;
  *             all peripherals mapped on these busses are running at MSI speed.
  *       	  - The clock for all peripherals is switched off, except the SRAM and FLASH.
  *           - All GPIOs are in input floating state, except the JTAG pins which
  *             are assigned to be used for debug purpose.
  *        
  *          Once the device started from reset, the user application has to:        
  *           - Configure the clock source to be used to drive the System clock
  *             (if the application needs higher frequency/performance)
  *           - Configure the System clock frequency and Flash settings  
  *           - Configure the AHB and APB busses prescalers
  *           - Enable the clock for the peripheral(s) to be used
  *           - Configure the clock source(s) for peripherals whose clocks are not
  *             derived from the System clock (ADC, RTC/LCD and IWDG)      
  *                        
  *  @endverbatim
  *    
  ******************************************************************************
  * @attention
  *
  * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
  * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
  * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
  * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
  * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
  * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
  *
  * <h2><center>&copy; COPYRIGHT 2010 STMicroelectronics</center></h2>
  ******************************************************************************  
  */ 

/* Includes ------------------------------------------------------------------*/
#include "stm32l1xx_rcc.h"

/** @addtogroup STM32L1xx_StdPeriph_Driver
  * @{
  */

/** @defgroup RCC 
  * @brief RCC driver modules
  * @{
  */ 

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/

/* ------------ RCC registers bit address in the alias region ----------- */
#define RCC_OFFSET                (RCC_BASE - PERIPH_BASE)

/* --- CR Register ---*/

/* Alias word address of HSION bit */
#define CR_OFFSET                 (RCC_OFFSET + 0x00)
#define HSION_BitNumber           0x00
#define CR_HSION_BB               (PERIPH_BB_BASE + (CR_OFFSET * 32) + (HSION_BitNumber * 4))

/* Alias word address of MSION bit */
#define MSION_BitNumber           0x08
#define CR_MSION_BB               (PERIPH_BB_BASE + (CR_OFFSET * 32) + (MSION_BitNumber * 4))

/* Alias word address of PLLON bit */
#define PLLON_BitNumber           0x18
#define CR_PLLON_BB               (PERIPH_BB_BASE + (CR_OFFSET * 32) + (PLLON_BitNumber * 4))

/* Alias word address of CSSON bit */
#define CSSON_BitNumber           0x1C
#define CR_CSSON_BB               (PERIPH_BB_BASE + (CR_OFFSET * 32) + (CSSON_BitNumber * 4))

/* --- CSR Register ---*/

/* Alias word address of LSION bit */
#define CSR_OFFSET                (RCC_OFFSET + 0x34)
#define LSION_BitNumber           0x00
#define CSR_LSION_BB              (PERIPH_BB_BASE + (CSR_OFFSET * 32) + (LSION_BitNumber * 4))

/* Alias word address of RTCEN bit */
#define RTCEN_BitNumber           0x16
#define CSR_RTCEN_BB              (PERIPH_BB_BASE + (CSR_OFFSET * 32) + (RTCEN_BitNumber * 4))

/* Alias word address of RTCRST bit */
#define RTCRST_BitNumber          0x17
#define CSR_RTCRST_BB             (PERIPH_BB_BASE + (CSR_OFFSET * 32) + (RTCRST_BitNumber * 4))


/* ---------------------- RCC registers mask -------------------------------- */
/* RCC Flag Mask */
#define FLAG_MASK                 ((uint8_t)0x1F)

/* CR register byte 3 (Bits[23:16]) base address */
#define CR_BYTE3_ADDRESS          ((uint32_t)0x40023802)

/* ICSCR register byte 4 (Bits[31:24]) base address */
#define ICSCR_BYTE4_ADDRESS       ((uint32_t)0x40023807)

/* CFGR register byte 3 (Bits[23:16]) base address */
#define CFGR_BYTE3_ADDRESS        ((uint32_t)0x4002380A)

/* CFGR register byte 4 (Bits[31:24]) base address */
#define CFGR_BYTE4_ADDRESS        ((uint32_t)0x4002380B)

/* CIR register byte 2 (Bits[15:8]) base address */
#define CIR_BYTE2_ADDRESS         ((uint32_t)0x4002380D)

/* CIR register byte 3 (Bits[23:16]) base address */
#define CIR_BYTE3_ADDRESS         ((uint32_t)0x4002380E)

/* CSR register byte 2 (Bits[15:8]) base address */
#define CSR_BYTE2_ADDRESS         ((uint32_t)0x40023835)

/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/

static __I uint8_t PLLMulTable[9] = {3, 4, 6, 8, 12, 16, 24, 32, 48};
static __I uint8_t APBAHBPrescTable[16] = {0, 0, 0, 0, 1, 2, 3, 4, 1, 2, 3, 4, 6, 7, 8, 9};

/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/

/** @defgroup RCC_Private_Functions
  * @{
  */

/** @defgroup RCC_Group1 Internal and external clocks, PLL, CSS and MCO configuration functions
 *  @brief   Internal and external clocks, PLL, CSS and MCO configuration functions 
 *
@verbatim   
 ===============================================================================
      Internal/external clocks, PLL, CSS and MCO configuration functions
 ===============================================================================  

  This section provide functions allowing to configure the internal/external clocks,
  PLL, CSS and MCO.
  
  1. HSI (high-speed internal), 16 MHz factory-trimmed RC used directly or through
     the PLL as System clock source.

  2. MSI (multi-speed internal), multispeed low power RC (65.536 KHz to 4.194 MHz)
     MHz used as System clock source.

  3. LSI (low-speed internal), 37 KHz low consumption RC used as IWDG and/or RTC
     clock source.

  4. HSE (high-speed external), 1 to 24 MHz crystal oscillator used directly or
     through the PLL as System clock source. Can be used also as RTC clock source.

  5. LSE (low-speed external), 32 KHz oscillator used as RTC clock source.   

  6. PLL (clocked by HSI or HSE), for System clock and USB (48 MHz).

  7. CSS (Clock security system), once enable and if a HSE clock failure occurs 
     (HSE used directly or through PLL as System clock source), the System clock
     is automatically switched to MSI and an interrupt is generated if enabled. 
     The interrupt is linked to the Cortex-M3 NMI (Non-Maskable Interrupt) 
     exception vector.   

  8. MCO (microcontroller clock output), used to output SYSCLK, HSI, MSI, HSE, PLL,
     LSI or LSE clock (through a configurable prescaler) on PA8 pin.

@endverbatim
  * @{
  */

/**
  * @brief  Resets the RCC clock configuration to the default reset state.
  * @note   - The default reset state of the clock configuration is given below:
  *            - MSI ON and used as system clock source (MSI range is not modified
  *              by this function, it keep the value configured by user application)
  *            - HSI, HSE and PLL OFF
  *            - AHB, APB1 and APB2 prescaler set to 1.
  *            - CSS and MCO OFF
  *            - All interrupts disabled
  *         - However, this function doesn't modify the configuration of the
  *            - Peripheral clocks
  *            - LSI, LSE and RTC clocks                  
  * @param  None
  * @retval None
  */
void RCC_DeInit(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)0x88FFC00C;
  
  /* Reset HSION, HSEON, CSSON and PLLON bits */
  RCC->CR &= (uint32_t)0xEEFEFFFE;

  /* 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->CIR = 0x00000000;
}

/**
  * @brief  Configures the External High Speed oscillator (HSE).
  * @note   - After enabling the HSE (RCC_HSE_ON or RCC_HSE_Bypass), the application
  *           software should wait on HSERDY flag to be set indicating that HSE clock
  *           is stable and can be used to clock the PLL and/or system clock.
  *         - HSE state can not be changed if it is used directly or through the
  *           PLL as system clock. In this case, you have to select another source
  *           of the system clock then change the HSE state (ex. disable it).
  *         - The HSE is stopped by hardware when entering STOP and STANDBY modes.         
  * @note   This function reset the CSSON bit, so if the Clock security system(CSS)
  *         was previously enabled you have to enable it again after calling this
  *         function.
  * @param RCC_HSE: specifies the new state of the HSE.
  *   This parameter can be one of the following values:
  *     @arg RCC_HSE_OFF: turn OFF the HSE oscillator, HSERDY flag goes low after
  *                       6 HSE oscillator clock cycles.
  *     @arg RCC_HSE_ON: turn ON the HSE oscillator
  *     @arg RCC_HSE_Bypass: HSE oscillator bypassed with external clock
  * @retval None
  */
void RCC_HSEConfig(uint8_t RCC_HSE)
{
  /* Check the parameters */
  assert_param(IS_RCC_HSE(RCC_HSE));

  /* Reset HSEON and HSEBYP bits before configuring the HSE ------------------*/
  *(__IO uint8_t *) CR_BYTE3_ADDRESS = RCC_HSE_OFF;

  /* Set the new HSE configuration -------------------------------------------*/
  *(__IO uint8_t *) CR_BYTE3_ADDRESS = RCC_HSE;

}

/**
  * @brief  Waits for HSE start-up.
  * @note   This functions waits on HSERDY flag to be set and return SUCCESS if 
  *         this flag is set, otherwise returns ERROR if the timeout is reached 
  *         and this flag is not set. The timeout value is defined by the constant
  *         HSE_STARTUP_TIMEOUT in stm32l1xx.h file. You can tailor it depending
  *         on the HSE crystal used in your application. 
  * @param  None
  * @retval An ErrorStatus enumeration value:
  *          - SUCCESS: HSE oscillator is stable and ready to use
  *          - ERROR: HSE oscillator not yet ready
  */
ErrorStatus RCC_WaitForHSEStartUp(void)
{
  __IO uint32_t StartUpCounter = 0;
  ErrorStatus status = ERROR;
  FlagStatus HSEStatus = RESET;
  
  /* Wait till HSE is ready and if timeout is reached exit */
  do
  {
    HSEStatus = RCC_GetFlagStatus(RCC_FLAG_HSERDY);
    StartUpCounter++;  
  } while((StartUpCounter != HSE_STARTUP_TIMEOUT) && (HSEStatus == RESET));
  
  if (RCC_GetFlagStatus(RCC_FLAG_HSERDY) != RESET)
  {
    status = SUCCESS;
  }
  else
  {
    status = ERROR;
  }  
  return (status);
}

/**
  * @brief  Adjusts the Internal Multi Speed oscillator (MSI) calibration value.
  * @note   The calibration is used to compensate for the variations in voltage
  *         and temperature that influence the frequency of the internal MSI RC.
  *         Refer to the Application Note AN3300 for more details on how to  
  *         calibrate the MSI.
  * @param  MSICalibrationValue: specifies the MSI calibration trimming value.
  *   This parameter must be a number between 0 and 0xFF.
  * @retval None
  */
void RCC_AdjustMSICalibrationValue(uint8_t MSICalibrationValue)
{
  
  /* Check the parameters */
  assert_param(IS_RCC_MSI_CALIBRATION_VALUE(MSICalibrationValue));

  *(__IO uint8_t *) ICSCR_BYTE4_ADDRESS = MSICalibrationValue;  
}

/**
  * @brief  Configures the Internal Multi Speed oscillator (MSI) clock range.
  * @note   - After restart from Reset or wakeup from STANDBY, the MSI clock is 
  *           around 2.097 MHz. The MSI clock does not change after wake-up from
  *           STOP mode.
  *         - The MSI clock range can be modified on the fly.     
  * @param  RCC_MSIRange: specifies the MSI Clock range.
  *   This parameter must be one of the following values: