123 lines
4.6 KiB
C
123 lines
4.6 KiB
C
/*
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* Copyright (c) 2012, Freescale Semiconductor, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* o Redistributions of source code must retain the above copyright notice, this list
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* of conditions and the following disclaimer.
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*
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* o Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or
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* other materials provided with the distribution.
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*
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* o Neither the name of Freescale Semiconductor, Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#if !defined(__SPINLOCK_H__)
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#define __SPINLOCK_H__
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#include <stdint.h>
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#include <stdbool.h>
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//! @addtogroup spinlock
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//! @{
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////////////////////////////////////////////////////////////////////////////////
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// Definitions
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////////////////////////////////////////////////////////////////////////////////
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//! @brief Typedef for a spinlock.
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typedef struct _spinlock {
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uint32_t owner; //!< Lock count.
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// uint32_t owner; //!< Core number of the owning CPU.
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uint32_t _cacheLineFiller[7]; //! Padding to make the lock consume a full cache line (32 bytes).
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} spinlock_t __attribute__ ((aligned (32)));
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//! @brief Special timeout values for the spinlock.
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enum _spinlock_timeouts
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{
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//! Timeout value meaning do not block at all if the spinlock isn't free.
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kSpinlockNoWait = 0,
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//! Timeout value to use to wait indefinitely for the spinlock to become available.
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kSpinlockWaitForever = 0xffffffff
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};
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////////////////////////////////////////////////////////////////////////////////
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// Code
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////////////////////////////////////////////////////////////////////////////////
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#if defined(__cplusplus)
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extern "C" {
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#endif
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//! @name Spinlock API
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//@{
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//! @brief Initialize a new spinlock.
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//!
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//! The spinlock is initialized in the unlocked state. Call spinlock_lock() if you need it
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//! to be locked.
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//!
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//! @param lock Pointer to the new spinlock.
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void spinlock_init(spinlock_t * lock);
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//! @brief Lock the given spinlock.
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//!
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//! Use this function to lock a spinlock. If the spinlock is unlocked, it will be locked and
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//! this function will return immediately. However, if the spinlock is already locked then
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//! this function will block for up to @a timeout microseconds waiting for another thread to
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//! unlock it.
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//!
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//! If #kSpinlockNoWait is passed for the timeout, then the function will not block at all.
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//! In this case, either the spinlock is locked immediately or it is left untouched.
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//!
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//! To wait infinitely for the spinlock to become free, pass #kSpinlockWaitForever. If the
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//! spinlock is already locked and no other thread unlocks it, then this function will never
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//! return (i.e., deadlock).
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//!
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//! @param lock Pointer to the spinlock to lock.
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//! @param timeout Maximum number of microseconds to block waiting for the spinlock to become
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//! available if it was locked upon entry to this function.
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//!
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//! @retval 0 The spinlock was locked successfully.
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//! @retval 1 A timeout occurred while waiting for the spinlock to be unlocked.
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int spinlock_lock(spinlock_t * lock, uint32_t timeout);
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//! @brief Unlock the given spinlock.
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//!
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//! @param lock Pointer to the spinlock to unlock.
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void spinlock_unlock(spinlock_t * lock);
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//! @brief Check whether a spinlock is currently locked.
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//!
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//! @param lock Pointer to the spinlock to test.
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bool spinlock_is_locked(spinlock_t * lock);
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//@}
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#if defined(__cplusplus)
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}
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#endif
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//! @}
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#endif // __SPINLOCK_H__
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////////////////////////////////////////////////////////////////////////////////
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// EOF
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////////////////////////////////////////////////////////////////////////////////
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