1 /* 2 * Copyright (c) 2011-2015 Wind River Systems, Inc. 3 * SPDX-License-Identifier: Apache-2.0 4 */ 5 6 #include <zephyr/kernel.h> 7 #include <zephyr/tracing/tracing.h> 8 #include <zephyr/arch/cpu.h> 9 10 #ifndef CONFIG_ARCH_HAS_CUSTOM_CPU_IDLE 11 __pinned_func arch_cpu_idle(void)12void arch_cpu_idle(void) 13 { 14 sys_trace_idle(); 15 __asm__ volatile ( 16 "sti\n\t" 17 "hlt\n\t"); 18 } 19 #endif 20 21 #ifndef CONFIG_ARCH_HAS_CUSTOM_CPU_ATOMIC_IDLE 22 __pinned_func arch_cpu_atomic_idle(unsigned int key)23void arch_cpu_atomic_idle(unsigned int key) 24 { 25 sys_trace_idle(); 26 27 __asm__ volatile ( 28 "sti\n\t" 29 /* 30 * The following statement appears in "Intel 64 and IA-32 31 * Architectures Software Developer's Manual", regarding the 'sti' 32 * instruction: 33 * 34 * "After the IF flag is set, the processor begins responding to 35 * external, maskable interrupts after the next instruction is 36 * executed." 37 * 38 * Thus the IA-32 implementation of arch_cpu_atomic_idle() will 39 * atomically re-enable interrupts and enter a low-power mode. 40 */ 41 "hlt\n\t"); 42 43 /* restore interrupt lockout state before returning to caller */ 44 if ((key & 0x200U) == 0U) { 45 __asm__ volatile("cli"); 46 } 47 } 48 #endif 49