105 lines
2.3 KiB
C
105 lines
2.3 KiB
C
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/*
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* Copyright (c) 2019 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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*
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* @brief public sys_sem APIs.
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*/
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#ifndef ZEPHYR_INCLUDE_SYS_SEM_H_
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#define ZEPHYR_INCLUDE_SYS_SEM_H_
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/*
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* sys_sem exists in user memory working as counter semaphore for
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* user mode thread when user mode enabled. When user mode isn't
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* enabled, sys_sem behaves like k_sem.
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*/
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#include <kernel.h>
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#include <atomic.h>
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#include <zephyr/types.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* sys_sem structure
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*/
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struct sys_sem {
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#ifdef CONFIG_USERSPACE
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struct k_futex futex;
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int limit;
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#else
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struct k_sem kernel_sem;
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#endif
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};
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/**
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* @brief Initialize a semaphore.
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*
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* This routine initializes a semaphore instance, prior to its first use.
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*
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* @param sem Address of the semaphore.
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* @param initial_count Initial semaphore count.
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* @param limit Maximum permitted semaphore count.
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*
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* @retval 0 Initial success.
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* @retval -EINVAL Bad parameters, the value of limit should be located in
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* (0, INT_MAX] and initial_count shouldn't be greater than limit.
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*/
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int sys_sem_init(struct sys_sem *sem, unsigned int initial_count,
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unsigned int limit);
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/**
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* @brief Give a semaphore.
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*
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* This routine gives @a sem, unless the semaphore is already at its
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* maximum permitted count.
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*
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* @param sem Address of the semaphore.
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*
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* @retval 0 Semaphore given.
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* @retval -EINVAL Parameter address not recognized.
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* @retval -EACCES Caller does not have enough access.
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* @retval -EAGAIN Count reached Maximum permitted count and try again.
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*/
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int sys_sem_give(struct sys_sem *sem);
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/**
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* @brief Take a sys_sem.
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*
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* This routine takes @a sem.
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*
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* @param sem Address of the sys_sem.
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* @param timeout Waiting period to take the sys_sem (in milliseconds),
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* or one of the special values K_NO_WAIT and K_FOREVER.
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*
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* @retval 0 sys_sem taken.
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* @retval -EINVAL Parameter address not recognized.
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* @retval -ETIMEDOUT Waiting period timed out.
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* @retval -EACCES Caller does not have enough access.
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*/
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int sys_sem_take(struct sys_sem *sem, s32_t timeout);
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/**
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* @brief Get sys_sem's value
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*
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* This routine returns the current value of @a sem.
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*
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* @param sem Address of the sys_sem.
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*
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* @return Current value of sys_sem.
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*/
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unsigned int sys_sem_count_get(struct sys_sem *sem);
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#ifdef __cplusplus
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}
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#endif
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#endif
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