text: /****************************************************************************
   * arch/arm/src/stm32/stm32_pmstop.c
   *
   *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * 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 <stdbool.h>
  
  #include "up_arch.h"
  #include "nvic.h"
  #include "stm32_pwr.h"
  #include "stm32_pm.h"
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /****************************************************************************
   * Private Data
   ****************************************************************************/
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: stm32_pmstop
   *
   * Description:
   *   Enter STOP mode.
   *
   * Input Parameters:
   *   lpds - true: To further reduce power consumption in Stop mode, put the
   *          internal voltage regulator in low-power mode using the LPDS bit
   *          of the Power control register (PWR_CR).
   *
   * Returned Value:
   *   Zero means that the STOP was successfully entered and the system has
   *   been re-awakened.  The internal voltage regulator is back to its
   *   original state.  Otherwise, STOP mode did not occur and a negated
   *   errno value is returned to indicate the cause of the failure.
   *
   ****************************************************************************/
  
  int stm32_pmstop(bool lpds)
  {
    uint32_t regval;
  
    /* Clear the Power Down Deep Sleep (PDDS) and the Low Power Deep Sleep
     * (LPDS)) bits in the power control register.
     */
  
    regval  = getreg32(STM32_PWR_CR);
    regval &= ~(PWR_CR_LPDS | PWR_CR_PDDS);
  
    /* Set the Low Power Deep Sleep (LPDS) bit if so requested */
  
    if (lpds)
      {
        regval |= PWR_CR_LPDS;
      }
  
    putreg32(regval, STM32_PWR_CR);
  
    /* Set SLEEPDEEP bit of Cortex System Control Register */
  
    regval  = getreg32(NVIC_SYSCON);
    regval |= NVIC_SYSCON_SLEEPDEEP;
    putreg32(regval, NVIC_SYSCON);
  
    /* Sleep until the wakeup interrupt or event occurs */
  
  #ifdef CONFIG_PM_WFE
    /* Mode: SLEEP + Entry with WFE */
  
    asm("wfe");
  #else
    /* Mode: SLEEP + Entry with WFI */
  
    asm("wfi");
  #endif
    return OK;
  }
  