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/****************************************************************************
* arch/arm/src/stm32/stm32_pmstandby.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_pmstandby
*
* Description:
* Enter STANDBY mode.
*
* Input Parameters:
* None
*
* Returned Value.
* On success, this function will not return (STANDBY mode can only be
* terminated with a reset event). Otherwise, STANDBY mode did not occur
* and a negated errno value is returned to indicate the cause of the
* failure.
*
* Assumptions:
* The caller holds the PM semaphore (g_pmsem) if this function is used
* as part of the NuttX power management logic.
*
****************************************************************************/
int stm32_pmstandby(void)
{
uint32_t regval;
/* Clear the Wake-Up Flag by setting the CWUF bit in the power control
* register.
*/
regval = getreg32(STM32_PWR_CR);
regval |= PWR_CR_CWUF;
putreg32(regval, STM32_PWR_CR);
/* Set the Power Down Deep Sleep (PDDS) bit in the power control register. */
regval |= PWR_CR_PDDS;
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 reset occurs */
asm("WFI");
return OK; /* Won't get here */
}
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