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/* SPDX-License-Identifier: BSD-2-Clause */
/* Shared Memory Lock Routines
*
* This shared memory locked queue support routine need to be
* able to lock the specified locked queue. Interrupts are
* disabled while the queue is locked to prevent preemption
* and deadlock when two tasks poll for the same lock.
* previous level.
*
* COPYRIGHT (c) 1989-1999.
* On-Line Applications Research Corporation (OAR).
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <rtems.h>
#include <bsp.h>
#include <shm_driver.h>
/*
* Shm_Initialize_lock
*
* Initialize the lock for the specified locked queue.
*/
void Shm_Initialize_lock(
Shm_Locked_queue_Control *lq_cb
)
{
lq_cb->lock = LQ_UNLOCKED;
}
/* void _Shm_Lock( &lq_cb )
*
* This shared memory locked queue support routine locks the
* specified locked queue. It disables interrupts to prevent
* a deadlock condition.
*/
void Shm_Lock(
Shm_Locked_queue_Control *lq_cb
)
{
uint32_t isr_level;
uint32_t *lockptr = (uint32_t*) &lq_cb->lock;
uint32_t lock_value;
lock_value = 0x80000000;
rtems_interrupt_disable( isr_level );
Shm_isrstat = isr_level;
while ( lock_value ) {
__asm__ volatile( ""
: "=r" (lockptr), "=r" (lock_value)
: "0" (lockptr), "1" (lock_value)
);
/*
* If not available, then may want to delay to reduce load on lock.
*
* NOTE: BSP must initialize the counter facility. Delay value is BSP
* dependent.
*/
if ( lock_value )
rtems_counter_delay_nanoseconds( 100 );
}
}
/*
* Shm_Unlock
*
* Unlock the lock for the specified locked queue.
*/
void Shm_Unlock(
Shm_Locked_queue_Control *lq_cb
)
{
uint32_t isr_level;
lq_cb->lock = SHM_UNLOCK_VALUE;
isr_level = Shm_isrstat;
rtems_interrupt_enable( isr_level );
}
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