diff --git a/arch/arm/src/stm32/stm32_pm.h b/arch/arm/src/stm32/stm32_pm.h index 8feee1f566..7292c04f44 100644 --- a/arch/arm/src/stm32/stm32_pm.h +++ b/arch/arm/src/stm32/stm32_pm.h @@ -125,10 +125,7 @@ int stm32_pmstandby(void); * - false: SLEEPONEXIT bit is cleared, the MCU enters Sleep mode * as soon as WFI or WFE instruction is executed. * 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. + * None * ****************************************************************************/ diff --git a/arch/arm/src/stm32/stm32_pmsleep.c b/arch/arm/src/stm32/stm32_pmsleep.c index 49ebf1ce75..05d767a081 100644 --- a/arch/arm/src/stm32/stm32_pmsleep.c +++ b/arch/arm/src/stm32/stm32_pmsleep.c @@ -77,10 +77,7 @@ * - false: SLEEPONEXIT bit is cleared, the MCU enters Sleep mode * as soon as WFI or WFE instruction is executed. * 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. + * None * ****************************************************************************/ diff --git a/arch/arm/src/stm32f7/Make.defs b/arch/arm/src/stm32f7/Make.defs index f4e64dea16..0930a9277e 100644 --- a/arch/arm/src/stm32f7/Make.defs +++ b/arch/arm/src/stm32f7/Make.defs @@ -134,6 +134,13 @@ ifeq ($(CONFIG_STM32F7_DMA),y) CHIP_CSRCS += stm32_dma.c endif +ifeq ($(CONFIG_PM),y) +CHIP_CSRCS += stm32_pmstandby.c stm32_pmstop.c stm32_pmsleep.c +ifneq ($(CONFIG_ARCH_CUSTOM_PMINIT),y) +CHIP_CSRCS += stm32_pminitialize.c +endif +endif + ifeq ($(CONFIG_STM32F7_PWR),y) CHIP_CSRCS += stm32_pwr.c stm32_exti_pwr.c endif diff --git a/arch/arm/src/stm32f7/stm32_pm.h b/arch/arm/src/stm32f7/stm32_pm.h new file mode 100644 index 0000000000..60d2972188 --- /dev/null +++ b/arch/arm/src/stm32f7/stm32_pm.h @@ -0,0 +1,122 @@ +/************************************************************************************ + * arch/arm/src/stm32f7/stm32_pm.h + * + * Copyright (C) 2018 Haltian Ltd. All rights reserved. + * Author: Juha Niskanen + * + * 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. + * + ************************************************************************************/ + +#ifndef __ARCH_ARM_SRC_STM32F7_STM32_PM_H +#define __ARCH_ARM_SRC_STM32F7_STM32_PM_H + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include + +#include + +#include "chip.h" +#include "up_internal.h" + +/**************************************************************************** + * Public Function Prototypes + ****************************************************************************/ + +#ifndef __ASSEMBLY__ +#ifdef __cplusplus +#define EXTERN extern "C" +extern "C" +{ +#else +#define EXTERN extern +#endif + +/**************************************************************************** + * 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 under-drive mode using the + * LPDS and LPUDS bits of the Power control register (PWR_CR1). + * + * Returned Value: + * None + * + ****************************************************************************/ + +void stm32_pmstop(bool lpds); + +/**************************************************************************** + * Name: stm32_pmstandby + * + * Description: + * Enter STANDBY mode. + * + * Input Parameters: + * None + * + * Returned Value: + * None + * + ****************************************************************************/ + +void stm32_pmstandby(void); + +/**************************************************************************** + * Name: stm32_pmsleep + * + * Description: + * Enter SLEEP mode. + * + * Input Parameters: + * sleeponexit - true: SLEEPONEXIT bit is set when the WFI instruction is + * executed, the MCU enters Sleep mode as soon as it + * exits the lowest priority ISR. + * - false: SLEEPONEXIT bit is cleared, the MCU enters Sleep mode + * as soon as WFI or WFE instruction is executed. + * Returned Value: + * None + * + ****************************************************************************/ + +void stm32_pmsleep(bool sleeponexit); + +#undef EXTERN +#ifdef __cplusplus +} +#endif +#endif /* __ASSEMBLY__ */ + +#endif /* __ARCH_ARM_SRC_STM32F7_STM32_PM_H */ diff --git a/arch/arm/src/stm32f7/stm32_pminitialize.c b/arch/arm/src/stm32f7/stm32_pminitialize.c new file mode 100644 index 0000000000..600dab75e2 --- /dev/null +++ b/arch/arm/src/stm32f7/stm32_pminitialize.c @@ -0,0 +1,78 @@ +/**************************************************************************** + * arch/arm/src/stm32f7/stm32_pminitialize.c + * + * Copyright (C) 2012, 2017 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt + * + * 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 + +#include + +#include "up_internal.h" +#include "stm32_pm.h" + +#ifdef CONFIG_PM + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: up_pminitialize + * + * Description: + * This function is called by MCU-specific logic at power-on reset in + * order to provide one-time initialization the power management subystem. + * This function must be called *very* early in the initialization sequence + * *before* any other device drivers are initialized (since they may + * attempt to register with the power management subsystem). + * + * Input Parameters: + * None. + * + * Returned Value: + * None. + * + ****************************************************************************/ + +void up_pminitialize(void) +{ + /* Then initialize the NuttX power management subsystem proper */ + + pm_initialize(); +} + +#endif /* CONFIG_PM */ diff --git a/arch/arm/src/stm32f7/stm32_pmsleep.c b/arch/arm/src/stm32f7/stm32_pmsleep.c new file mode 100644 index 0000000000..64bd4d6a8e --- /dev/null +++ b/arch/arm/src/stm32f7/stm32_pmsleep.c @@ -0,0 +1,101 @@ +/**************************************************************************** + * arch/arm/src/stm32f7/stm32_pmsleep.c + * + * Copyright (C) 2012, 2017 Gregory Nutt. All rights reserved. + * Authors: Gregory Nutt + * Diego Sanchez + * + * 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 + +#include + +#include "up_arch.h" +#include "nvic.h" +#include "stm32_pwr.h" +#include "stm32_pm.h" + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: stm32_pmsleep + * + * Description: + * Enter SLEEP mode. + * + * Input Parameters: + * sleeponexit - true: SLEEPONEXIT bit is set when the WFI instruction is + * executed, the MCU enters Sleep mode as soon as it + * exits the lowest priority ISR. + * - false: SLEEPONEXIT bit is cleared, the MCU enters Sleep mode + * as soon as WFI or WFE instruction is executed. + * Returned Value: + * None + * + ****************************************************************************/ + +void stm32_pmsleep(bool sleeponexit) +{ + uint32_t regval; + + /* Clear SLEEPDEEP bit of Cortex System Control Register */ + + regval = getreg32(NVIC_SYSCON); + regval &= ~NVIC_SYSCON_SLEEPDEEP; + if (sleeponexit) + { + regval |= NVIC_SYSCON_SLEEPONEXIT; + } + else + { + regval &= ~NVIC_SYSCON_SLEEPONEXIT; + } + + 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 +} diff --git a/arch/arm/src/stm32f7/stm32_pmstandby.c b/arch/arm/src/stm32f7/stm32_pmstandby.c new file mode 100644 index 0000000000..9f58a8967b --- /dev/null +++ b/arch/arm/src/stm32f7/stm32_pmstandby.c @@ -0,0 +1,96 @@ +/**************************************************************************** + * arch/arm/src/stm32f7/stm32_pmstandby.c + * + * Copyright (C) 2018 Haltian Ltd. All rights reserved. + * Author: Juha Niskanen + * + * 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 + +#include + +#include "up_arch.h" +#include "nvic.h" +#include "stm32_rcc.h" +#include "stm32_pwr.h" +#include "stm32_pm.h" + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: stm32_pmstandby + * + * Description: + * Enter STANDBY mode. + * + * Input Parameters: + * None + * + * Returned Value: + * None + * + ****************************************************************************/ + +void stm32_pmstandby(void) +{ + uint32_t regval; + + /* Clear the wake-up flags before reseting. */ + + modifyreg32(STM32_PWR_CR1, 0, PWR_CR1_CSBF); + modifyreg32(STM32_PWR_CR2, 0, PWR_CR2_CWUPF1 | PWR_CR2_CWUPF2 | + PWR_CR2_CWUPF3 | PWR_CR2_CWUPF4 | + PWR_CR2_CWUPF5 | PWR_CR2_CWUPF6); + + /* Clear reset flags. */ + + modifyreg32(STM32_RCC_CSR, 0, RCC_CSR_RMVF); + + /* Set the Power Down Deep Sleep (PDDS) bit in the power control register. */ + + modifyreg32(STM32_PWR_CR1, 0, PWR_CR1_PDDS); + + /* 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"); +} diff --git a/arch/arm/src/stm32f7/stm32_pmstop.c b/arch/arm/src/stm32f7/stm32_pmstop.c new file mode 100644 index 0000000000..c6ec37ce91 --- /dev/null +++ b/arch/arm/src/stm32f7/stm32_pmstop.c @@ -0,0 +1,129 @@ +/**************************************************************************** + * arch/arm/src/stm32f7/stm32_pmstop.c + * + * Copyright (C) 2018 Haltian Ltd. All rights reserved. + * Author: Juha Niskanen + * + * 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 + +#include + +#include "up_arch.h" +#include "nvic.h" +#include "stm32_pwr.h" +#include "stm32_pm.h" + +/**************************************************************************** + * 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 under-drive mode using the + * LPDS and LPUDS bits of the Power control register (PWR_CR1). + * + * Returned Value: + * None + * + ****************************************************************************/ + +void stm32_pmstop(bool lpds) +{ + uint32_t regval; + + /* Clear the Power Down Deep Sleep (PDDS), the Low Power Deep Sleep + * (LPDS), Under-Drive Enable in Stop Mode (UDEN), Flash Power Down in Stop + * Mode (FPDS), Main Regulator in Deepsleep Under-Drive Mode (MRUDS), and + * Low-power Regulator in Deepsleep Under-Drive Mode (LPUDS) bits in + * the power control register. + */ + + regval = getreg32(STM32_PWR_CR1); + regval &= ~(PWR_CR1_LPDS | PWR_CR1_PDDS | PWR_CR1_FPDS); + regval &= ~(PWR_CR1_UDEN_ENABLE | PWR_CR1_MRUDS | PWR_CR1_LPUDS); + + /* Set under-drive enabled with low-power regulator. */ + + if (lpds) + { + regval |= PWR_CR1_UDEN_ENABLE | PWR_CR1_LPUDS | PWR_CR1_LPDS; + } + + putreg32(regval, STM32_PWR_CR1); + + /* 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 volatile ("wfe"); +#else + /* Mode: SLEEP + Entry with WFI */ + + asm volatile ("wfi"); +#endif + + /* Clear deep sleep bits, so that MCU does not go into deep sleep in idle. */ + + /* Clear the Power Down Deep Sleep (PDDS), the Low Power Deep Sleep + * (LPDS) bits, Under-Drive Enable in Stop Mode (UDEN), Main Regulator in + * Deepsleep Under-Drive Mode (MRUDS), and Low-power Regulator in Deepsleep + * Under-Drive Mode (LPUDS) in the power control register. + */ + + regval = getreg32(STM32_PWR_CR1); + regval &= ~(PWR_CR1_LPDS | PWR_CR1_PDDS); + regval &= ~(PWR_CR1_UDEN_ENABLE | PWR_CR1_MRUDS | PWR_CR1_LPUDS); + putreg32(regval, STM32_PWR_CR1); + + /* Clear SLEEPDEEP bit of Cortex System Control Register */ + + regval = getreg32(NVIC_SYSCON); + regval &= ~NVIC_SYSCON_SLEEPDEEP; + putreg32(regval, NVIC_SYSCON); +} diff --git a/arch/arm/src/stm32l4/stm32l4_pm.h b/arch/arm/src/stm32l4/stm32l4_pm.h index 530be06fcb..b12f523a88 100644 --- a/arch/arm/src/stm32l4/stm32l4_pm.h +++ b/arch/arm/src/stm32l4/stm32l4_pm.h @@ -131,10 +131,7 @@ int stm32l4_pmstandby(void); * - false: SLEEPONEXIT bit is cleared, the MCU enters Sleep mode * as soon as WFI or WFE instruction is executed. * 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. + * None * ****************************************************************************/ diff --git a/arch/arm/src/stm32l4/stm32l4_pmsleep.c b/arch/arm/src/stm32l4/stm32l4_pmsleep.c index 2a5ebcd58a..15dd2d9db4 100644 --- a/arch/arm/src/stm32l4/stm32l4_pmsleep.c +++ b/arch/arm/src/stm32l4/stm32l4_pmsleep.c @@ -64,10 +64,7 @@ * - false: SLEEPONEXIT bit is cleared, the MCU enters Sleep mode * as soon as WFI or WFE instruction is executed. * 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. + * None * ****************************************************************************/