mirror of https://github.com/ARMmbed/mbed-os.git
101 lines
3.3 KiB
C
101 lines
3.3 KiB
C
/*******************************************************************************
|
|
* Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a
|
|
* copy of this software and associated documentation files (the "Software"),
|
|
* to deal in the Software without restriction, including without limitation
|
|
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
|
|
* and/or sell copies of the Software, and to permit persons to whom the
|
|
* Software is furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included
|
|
* in all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
|
|
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
|
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
|
|
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
|
|
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
|
|
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
|
|
* OTHER DEALINGS IN THE SOFTWARE.
|
|
*
|
|
* Except as contained in this notice, the name of Maxim Integrated
|
|
* Products, Inc. shall not be used except as stated in the Maxim Integrated
|
|
* Products, Inc. Branding Policy.
|
|
*
|
|
* The mere transfer of this software does not imply any licenses
|
|
* of trade secrets, proprietary technology, copyrights, patents,
|
|
* trademarks, maskwork rights, or any other form of intellectual
|
|
* property whatsoever. Maxim Integrated Products, Inc. retains all
|
|
* ownership rights.
|
|
*
|
|
* $Date: 2016-03-11 11:46:37 -0600 (Fri, 11 Mar 2016) $
|
|
* $Revision: 21839 $
|
|
*
|
|
******************************************************************************/
|
|
|
|
/**
|
|
* @file mxc_lock.h
|
|
* @brief Used to create exclusion for critical sections.
|
|
*/
|
|
|
|
#ifndef _MXC_LOCK_H_
|
|
#define _MXC_LOCK_H_
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
/***** Includes *****/
|
|
#include "mxc_config.h"
|
|
|
|
/***** Definitions *****/
|
|
|
|
/***** Globals *****/
|
|
|
|
/***** Function Prototypes *****/
|
|
|
|
/**
|
|
* @brief Attempts to acquire the lock.
|
|
* @param lock Pointer to variable used for the lock.
|
|
* @param value Value to be place in the lock. Can not be 0.
|
|
* @details This in an interrupt safe function that can be used as a mutex.
|
|
The lock variable must remain in scope until the lock is released.
|
|
Will not block if another thread has acquired the lock.
|
|
* @returns E_NO_ERROR if everything successful, E_BUSY if lock is taken.
|
|
*/
|
|
__STATIC_INLINE int mxc_get_lock(uint32_t *lock, uint32_t value)
|
|
{
|
|
do {
|
|
|
|
// Return if the lock is taken by a different thread
|
|
if(__LDREXW((volatile uint32_t *)lock) != 0) {
|
|
return E_BUSY;
|
|
}
|
|
|
|
// Attempt to take the lock
|
|
} while(__STREXW(value, (volatile unsigned long *)lock) != 0);
|
|
|
|
// Do not start any other memory access until memory barrier is complete
|
|
__DMB();
|
|
|
|
return E_NO_ERROR;
|
|
}
|
|
|
|
/**
|
|
* @brief Free the given lock.
|
|
* @param lock Pointer to variable used for the lock.
|
|
*/
|
|
__STATIC_INLINE void mxc_free_lock(uint32_t *lock)
|
|
{
|
|
// Ensure memory operations complete before releasing lock
|
|
__DMB();
|
|
*lock = 0;
|
|
}
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* _MXC_LOCK_H_ */
|