67 lines
2.1 KiB
C
67 lines
2.1 KiB
C
/*
|
|
* Copyright (c) 2016 Intel Corporation
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include <nanokernel.h>
|
|
#include <nano_private.h>
|
|
|
|
/**
|
|
*
|
|
* @brief Power save idle routine
|
|
*
|
|
* This function will be called by the nanokernel idle loop or possibly within
|
|
* an implementation of _sys_power_save_idle in the microkernel when the
|
|
* '_sys_power_save_flag' variable is non-zero.
|
|
*
|
|
* @return N/A
|
|
*/
|
|
void nano_cpu_idle(void)
|
|
{
|
|
/* Do nothing but unconditionally unlock interrupts and return to the
|
|
* caller. This CPU does not have any kind of power saving instruction.
|
|
*/
|
|
irq_unlock(NIOS2_STATUS_PIE_MSK);
|
|
}
|
|
|
|
/**
|
|
*
|
|
* @brief Atomically re-enable interrupts and enter low power mode
|
|
*
|
|
* This function is utilized by the nanokernel object "wait" APIs for tasks,
|
|
* e.g. nano_task_lifo_get(), nano_task_sem_take(),
|
|
* nano_task_stack_pop(), and nano_task_fifo_get().
|
|
*
|
|
* INTERNAL
|
|
* The requirements for nano_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 nano_task_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 nano_cpu_atomic_idle(unsigned int key)
|
|
{
|
|
/* Do nothing but restore IRQ state. This CPU does not have any
|
|
* kind of power saving instruction.
|
|
*/
|
|
irq_unlock(key);
|
|
}
|
|
|