| /* |
| * 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); |
| } |
| |