1 /*
2 * Copyright (c) 2017 Jean-Paul Etienne <fractalclone@gmail.com>
3 * Contributors: 2018 Antmicro <www.antmicro.com>
4 *
5 * SPDX-License-Identifier: Apache-2.0
6 */
7
8 #include <zephyr/toolchain.h>
9 #include <zephyr/irq.h>
10 #include <zephyr/arch/cpu.h>
11
12 #include <zephyr/tracing/tracing.h>
13
riscv_idle(unsigned int key)14 static ALWAYS_INLINE void riscv_idle(unsigned int key)
15 {
16 sys_trace_idle();
17 /* unlock interrupts */
18 irq_unlock(key);
19
20 /* Wait for interrupt */
21 __asm__ volatile("wfi");
22 }
23
24 /**
25 * @brief Power save idle routine
26 *
27 * This function will be called by the kernel idle loop or possibly within
28 * an implementation of _pm_save_idle in the kernel when the
29 * '_pm_save_flag' variable is non-zero.
30 */
arch_cpu_idle(void)31 void arch_cpu_idle(void)
32 {
33 riscv_idle(MSTATUS_IEN);
34 }
35
36 /**
37 * @brief Atomically re-enable interrupts and enter low power mode
38 *
39 * INTERNAL
40 * The requirements for arch_cpu_atomic_idle() are as follows:
41 * 1) The enablement of interrupts and entering a low-power mode needs to be
42 * atomic, i.e. there should be no period of time where interrupts are
43 * enabled before the processor enters a low-power mode. See the comments
44 * in k_lifo_get(), for example, of the race condition that
45 * occurs if this requirement is not met.
46 *
47 * 2) After waking up from the low-power mode, the interrupt lockout state
48 * must be restored as indicated in the 'imask' input parameter.
49 */
arch_cpu_atomic_idle(unsigned int key)50 void arch_cpu_atomic_idle(unsigned int key)
51 {
52 riscv_idle(key);
53 }
54
