path: root/nuttx/arch/arm/src/stm32/stm32_pmstop.c

/****************************************************************************
 * 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 volatage 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;
}