mirror of
https://github.com/mist-devel/mist-firmware.git
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89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
/* ----------------------------------------------------------------------------
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* SAM Software Package License
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* ----------------------------------------------------------------------------
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* Copyright (c) 2015, Atmel Corporation
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*
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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
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the disclaimer below.
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*
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* Atmel's name may not be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
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* DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* ----------------------------------------------------------------------------
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*/
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#include "barriers.h"
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#include "chip.h"
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#include "mutex.h"
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#include "cpuidle.h"
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#include <stdint.h>
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#include <stdbool.h>
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#define MUTEX_LOCKED 1
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#define MUTEX_UNLOCKED 0
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void mutex_lock(mutex_t* mutex)
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{
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while (!mutex_try_lock(mutex)) {
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cpu_idle();
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}
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}
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#if defined(CONFIG_ARCH_ARMV7A) || defined(CONFIG_ARCH_ARMV7M)
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bool mutex_try_lock(mutex_t* mutex)
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{
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uint32_t value;
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while (true)
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{
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// Read the current mutex value and tag the mutex address for exclusive access by the executing processor
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__asm volatile("ldrex %0, [%1]" : "=r"(value) : "r"(mutex));
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if (value != MUTEX_UNLOCKED)
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return false;
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// Provided the executing processor still has exclusive access to the mutex address, lock it now
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__asm volatile("strex %0, %1, [%2]" : "=&r"(value) : "r"(MUTEX_LOCKED), "r"(mutex));
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if (value == 0) /* Check if strex was ok */
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break;
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}
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dmb();
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return true;
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}
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#elif defined(CONFIG_ARCH_ARMV5TE)
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bool mutex_try_lock(mutex_t* mutex)
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{
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uint32_t value;
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asm("swp %0, %1, [%2]" : "=&r"(value) : "r"(MUTEX_LOCKED), "r"(mutex));
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return value == MUTEX_UNLOCKED;
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}
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#endif
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void mutex_unlock(mutex_t* mutex)
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{
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dmb();
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*mutex = MUTEX_UNLOCKED;
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}
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bool mutex_is_locked(const mutex_t* mutex)
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{
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return *mutex != MUTEX_UNLOCKED;
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}
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