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* Copyright (c) 2013-2014 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief ARM Cortex-M power management
*
*/
#include <offsets_short.h>
#include <toolchain.h>
#include <linker/sections.h>
#include <arch/cpu.h>
#ifdef CONFIG_TICKLESS_IDLE
#include <kernel_structs.h>
#endif
_ASM_FILE_PROLOGUE
GTEXT(_CpuIdleInit)
#ifdef CONFIG_SYS_POWER_MANAGEMENT
GTEXT(_NanoIdleValGet)
GTEXT(_NanoIdleValClear)
#endif
GTEXT(k_cpu_idle)
GTEXT(k_cpu_atomic_idle)
#define _SCB_SCR 0xE000ED10
#define _SCB_SCR_SEVONPEND (1 << 4)
#define _SCB_SCR_SLEEPDEEP (1 << 2)
#define _SCB_SCR_SLEEPONEXIT (1 << 1)
#define _SCR_INIT_BITS _SCB_SCR_SEVONPEND
/**
*
* @brief Initialization of CPU idle
*
* Only called by kernel_arch_init(). Sets SEVONPEND bit once for the system's
* duration.
*
* @return N/A
*
* C function prototype:
*
* void _CpuIdleInit (void);
*/
SECTION_FUNC(TEXT, _CpuIdleInit)
ldr r1, =_SCB_SCR
movs.n r2, #_SCR_INIT_BITS
str r2, [r1]
bx lr
#ifdef CONFIG_SYS_POWER_MANAGEMENT
/**
*
* @brief Get the kernel idle setting
*
* Returns the kernel idle setting, in ticks. Only called by __systick().
*
* @return the requested number of ticks for the kernel to be idle
*
* C function prototype:
*
* s32_t _NanoIdleValGet (void);
*/
SECTION_FUNC(TEXT, _NanoIdleValGet)
ldr r0, =_kernel
ldr r0, [r0, #_kernel_offset_to_idle]
bx lr
/**
*
* @brief Clear the kernel idle setting
*
* Sets the kernel idle setting to 0. Only called by __systick().
*
* @return N/A
*
* C function prototype:
*
* void _NanoIdleValClear (void);
*/
SECTION_FUNC(TEXT, _NanoIdleValClear)
ldr r0, =_kernel
eors.n r1, r1
str r1, [r0, #_kernel_offset_to_idle]
bx lr
#endif /* CONFIG_SYS_POWER_MANAGEMENT */
/**
*
* @brief Power save idle routine for ARM Cortex-M
*
* This function will be called by the kernel idle loop or possibly within
* an implementation of _sys_power_save_idle in the kernel when the
* '_sys_power_save_flag' variable is non-zero. The ARM 'wfi' instruction
* will be issued, causing a low-power consumption sleep mode.
*
* @return N/A
*
* C function prototype:
*
* void k_cpu_idle (void);
*/
SECTION_FUNC(TEXT, k_cpu_idle)
#ifdef CONFIG_KERNEL_EVENT_LOGGER_SLEEP
push {lr}
bl _sys_k_event_logger_enter_sleep
pop {r0}
mov lr, r0
#endif
#if defined(CONFIG_ARMV6_M)
cpsie i
#elif defined(CONFIG_ARMV7_M)
/* clear BASEPRI so wfi is awakened by incoming interrupts */
eors.n r0, r0
msr BASEPRI, r0
#else
#error Unknown ARM architecture
#endif /* CONFIG_ARMV6_M */
wfi
bx lr
/**
*
* @brief Atomically re-enable interrupts and enter low power mode
*
* INTERNAL
* The requirements for k_cpu_atomic_idle() are as follows:
* 1) The enablement of interrupts and entering a low-power mode needs to be
* atomic, i.e. there should be no period of time where interrupts are
* enabled before the processor enters a low-power mode. See the comments
* in k_lifo_get(), for example, of the race condition that occurs
* if this requirement is not met.
*
* 2) After waking up from the low-power mode, the interrupt lockout state
* must be restored as indicated in the 'imask' input parameter.
*
* @return N/A
*
* C function prototype:
*
* void k_cpu_atomic_idle (unsigned int imask);
*/
SECTION_FUNC(TEXT, k_cpu_atomic_idle)
#ifdef CONFIG_KERNEL_EVENT_LOGGER_SLEEP
push {lr}
bl _sys_k_event_logger_enter_sleep
pop {r1}
mov lr, r1
#endif
/*
* Lock PRIMASK while sleeping: wfe will still get interrupted by
* incoming interrupts but the CPU will not service them right away.
*/
cpsid i
/*
* No need to set SEVONPEND, it's set once in _CpuIdleInit() and never
* touched again.
*/
/* r0: interrupt mask from caller */
#if defined(CONFIG_ARMV6_M)
/* No BASEPRI, call wfe directly (SEVONPEND set in _CpuIdleInit()) */
wfe
cmp r0, #0
bne _irq_disabled
cpsie i
_irq_disabled:
#elif defined(CONFIG_ARMV7_M)
/* r1: zero, for setting BASEPRI (needs a register) */
eors.n r1, r1
/* unlock BASEPRI so wfe gets interrupted by incoming interrupts */
msr BASEPRI, r1
wfe
msr BASEPRI, r0
cpsie i
#else
#error Unknown ARM architecture
#endif /* CONFIG_ARMV6_M */
bx lr
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