text: /****************************************************************************
   * arch/arm/src/stm32l4/stm32l4_rcc.c
   *
   *   Copyright (C) 2009, 2011-2012 Gregory Nutt. All rights reserved.
   *   Copyright (C) 2016 Sebastien Lorquet. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *   Author: Sebastien Lorquet <sebastien@lorquet.fr>
   *
   * 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 NuttX 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 OWNER 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.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <stdint.h>
  #include <stdio.h>
  #include <assert.h>
  #include <debug.h>
  
  #include <arch/board/board.h>
  
  #include "up_internal.h"
  #include "up_arch.h"
  
  #include "chip.h"
  #include "stm32l4_rcc.h"
  #include "stm32l4_flash.h"
  #include "stm32l4.h"
  #include "stm32l4_waste.h"
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /* Allow up to 100 milliseconds for the high speed clock to become ready.
   * that is a very long delay, but if the clock does not become ready we are
   * hosed anyway.
   */
  
  #define HSERDY_TIMEOUT (100 * CONFIG_BOARD_LOOPSPERMSEC)
  
  /****************************************************************************
   * Private Data
   ****************************************************************************/
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /* Include chip-specific clocking initialization logic */
  
  #if defined(CONFIG_STM32L4_STM32L4X3)
  #  include "stm32l4x3xx_rcc.c"
  #elif defined(CONFIG_STM32L4_STM32L4X5)
  #  include "stm32l4x5xx_rcc.c"
  #elif defined(CONFIG_STM32L4_STM32L4X6)
  #  include "stm32l4x6xx_rcc.c"
  #else
  #  error "Unsupported STM32L4 chip"
  #endif
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: rcc_resetbkp
   *
   * Description:
   *   The RTC needs to reset the Backup Domain to change RTCSEL and resetting
   *   the Backup Domain renders to disabling the LSE as consequence.   In order
   *   to avoid resetting the Backup Domain when we already configured LSE we
   *   will reset the Backup Domain early (here).
   *
   * Input Parameters:
   *   None
   *
   * Returned Value:
   *   None
   *
   ****************************************************************************/
  
  #if defined(CONFIG_STM32L4_PWR) && defined(CONFIG_RTC)
  static inline void rcc_resetbkp(void)
  {
    bool init_stat;
  
    /* Check if the RTC is already configured */
  
    init_stat = stm32l4_rtc_is_initialized();
    if(!init_stat)
      {
         /* Enable write access to the backup domain (RTC registers, RTC
          * backup data registers and backup SRAM).
          */
  
        (void)stm32l4_pwr_enablebkp(true);
  
        /* We might be changing RTCSEL - to ensure such changes work, we must
         * reset the backup domain (having backed up the RTC_MAGIC token)
         */
  
         modifyreg32(STM32L4_RCC_BDCR, 0, RCC_BDCR_BDRST);
         modifyreg32(STM32L4_RCC_BDCR, RCC_BDCR_BDRST, 0);
  
         (void)stm32l4_pwr_enablebkp(false);
      }
  }
  #else
  #  define rcc_resetbkp()
  #endif
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: stm32l4_clockconfig
   *
   * Description:
   *   Called to establish the clock settings based on the values in board.h.
   *   This function (by default) will reset most everything, enable the PLL,
   *   and enable peripheral clocking for all peripherals enabled in the NuttX
   *   configuration file.
   *
   *   If CONFIG_ARCH_BOARD_STM32L4_CUSTOM_CLOCKCONFIG is defined, then clocking
   *   will be enabled by an externally provided, board-specific function called
   *   stm32l4_board_clockconfig().
   *
   * Input Parameters:
   *   None
   *
   * Returned Value:
   *   None
   *
   ****************************************************************************/
  
  void stm32l4_clockconfig(void)
  {
    /* Make sure that we are starting in the reset state */
  
    rcc_reset();
  
    /* Reset backup domain if appropriate */
  
    rcc_resetbkp();
  
  #if defined(CONFIG_ARCH_BOARD_STM32L4_CUSTOM_CLOCKCONFIG)
  
    /* Invoke Board Custom Clock Configuration */
  
    stm32l4_board_clockconfig();
  
  #else
  
    /* Invoke standard, fixed clock configuration based on definitions in board.h */
  
    stm32l4_stdclockconfig();
  
  #endif
  
    /* Enable peripheral clocking */
  
    rcc_enableperipherals();
  }
  
  /************************************************************************************
   * Name: stm32l4_clockenable
   *
   * Description:
   *   Re-enable the clock and restore the clock settings based on settings in board.h.
   *   This function is only available to support low-power modes of operation:  When
   *   re-awakening from deep-sleep modes, it is necessary to re-enable/re-start the
   *   PLL
   *
   *   This functional performs a subset of the operations performed by
   *   stm32l4_clockconfig():  It does not reset any devices, and it does not reset the
   *   currenlty enabled peripheral clocks.
   *
   *   If CONFIG_ARCH_BOARD_STM32L4_CUSTOM_CLOCKCONFIG is defined, then clocking will
   *   be enabled by an externally provided, board-specific function called
   *   stm32l4_board_clockconfig().
   *
   * Input Parameters:
   *   None
   *
   * Returned Value:
   *   None
   *
   ************************************************************************************/
  
  #ifdef CONFIG_PM
  void stm32l4_clockenable(void)
  {
  #if defined(CONFIG_ARCH_BOARD_STM32L4_CUSTOM_CLOCKCONFIG)
  
    /* Invoke Board Custom Clock Configuration */
  
    stm32l4_board_clockconfig();
  
  #else
  
    /* Invoke standard, fixed clock configuration based on definitions in board.h */
  
    stm32l4_stdclockconfig();
  
  #endif
  }
  #endif
  
  