mvme147s/mpci/lock.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /*  Shared Memory Lock Routines
0004  *
0005  *  This shared memory locked queue support routine need to be
0006  *  able to lock the specified locked queue.  Interrupts are
0007  *  disabled while the queue is locked to prevent preemption
0008  *  and deadlock when two tasks poll for the same lock.
0009  *  previous level.
0010  *
0011  *  COPYRIGHT (c) 1989-1999.
0012  *  On-Line Applications Research Corporation (OAR).
0013  *
0014  * Redistribution and use in source and binary forms, with or without
0015  * modification, are permitted provided that the following conditions
0016  * are met:
0017  * 1. Redistributions of source code must retain the above copyright
0018  *    notice, this list of conditions and the following disclaimer.
0019  * 2. Redistributions in binary form must reproduce the above copyright
0020  *    notice, this list of conditions and the following disclaimer in the
0021  *    documentation and/or other materials provided with the distribution.
0022  *
0023  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0024  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0025  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0026  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0027  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0028  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0029  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0030  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0031  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0032  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0033  * POSSIBILITY OF SUCH DAMAGE.
0034  */
0035
0036 #include <rtems.h>
0037 #include <bsp.h>
0038 #include <shm_driver.h>
0039
0040 /*
0041  *  Shm_Initialize_lock
0042  *
0043  *  Initialize the lock for the specified locked queue.
0044  */
0045
0046 void Shm_Initialize_lock(
0047   Shm_Locked_queue_Control *lq_cb
0048 )
0049 {
0050   lq_cb->lock = LQ_UNLOCKED;
0051 }
0052
0053 /*  void _Shm_Lock( &lq_cb )
0054  *
0055  *  This shared memory locked queue support routine locks the
0056  *  specified locked queue.  It disables interrupts to prevent
0057  *  a deadlock condition.
0058  */
0059
0060 void Shm_Lock(
0061   Shm_Locked_queue_Control *lq_cb
0062 )
0063 {
0064   uint32_t         isr_level;
0065   uint32_t         *lockptr = (uint32_t*)&lq_cb->lock;
0066
0067   rtems_interrupt_disable( isr_level );
0068     Shm_isrstat = isr_level;
0069     __asm__ volatile( "lockit:"    : : );
0070     __asm__ volatile( "tas %0@"    : "=a" (lockptr) : "0" (lockptr) );
0071     __asm__ volatile( "bne lockit" : : );
0072 /* should delay */
0073 }
0074
0075 /*
0076  *  Shm_Unlock
0077  *
0078  *  Unlock the lock for the specified locked queue.
0079  */
0080
0081 void Shm_Unlock(
0082   Shm_Locked_queue_Control *lq_cb
0083 )
0084 {
0085   uint32_t         isr_level;
0086
0087   lq_cb->lock = SHM_UNLOCK_VALUE;
0088   isr_level = Shm_isrstat;
0089   rtems_interrupt_enable( isr_level );
0090 }