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/*
* Copyright (c) 2016 Jean-Paul Etienne <fractalclone@gmail.com>
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <irq.h>
/*
* In RISC-V there is no conventional way to handle CPU power save.
* Each RISC-V SOC handles it in its own way.
* Hence, by default, k_cpu_idle and k_cpu_atomic_idle functions just
* unlock interrupts and return to the caller, without issuing any CPU power
* saving instruction.
*
* Nonetheless, define the default k_cpu_idle and k_cpu_atomic_idle
* functions as weak functions, so that they can be replaced at the SOC-level.
*/
/**
*
* @brief Power save idle routine
*
* 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.
*
* @return N/A
*/
void __weak k_cpu_idle(void)
{
irq_unlock(SOC_MSTATUS_IEN);
}
/**
*
* @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
*/
void __weak k_cpu_atomic_idle(unsigned int key)
{
irq_unlock(key);
}