130 lines
4.2 KiB
C
130 lines
4.2 KiB
C
/****************************************************************************
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* sched/irq/irq_spinlock.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <nuttx/spinlock.h>
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#include <sys/types.h>
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#include <arch/irq.h>
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#include "sched/sched.h"
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#if defined(CONFIG_SMP) && defined (CONFIG_SPINLOCK_IRQ)
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/****************************************************************************
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* Public Data
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****************************************************************************/
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/* Used for access control */
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static volatile spinlock_t g_irq_spin SP_SECTION = SP_UNLOCKED;
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/* Handles nested calls to spin_lock_irqsave and spin_unlock_irqrestore */
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static volatile uint8_t g_irq_spin_count[CONFIG_SMP_NCPUS];
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: spin_lock_irqsave
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*
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* Description:
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* If SMP and SPINLOCK_IRQ are enabled:
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* Disable local interrupts and take the global spinlock (g_irq_spin)
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* if the call counter (g_irq_spin_count[cpu]) equals to 0. Then the
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* counter on the CPU is increment to allow nested call.
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*
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* NOTE: This API is very simple to protect data (e.g. H/W register
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* or internal data structure) in SMP mode. But do not use this API
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* with kernel APIs which suspend a caller thread. (e.g. nxsem_wait)
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*
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* If SMP and SPINLOCK_IRQ are not enabled:
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* This function is equivalent to enter_critical_section().
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* An opaque, architecture-specific value that represents the state of
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* the interrupts prior to the call to spin_lock_irqsave();
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*
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****************************************************************************/
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irqstate_t spin_lock_irqsave(void)
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{
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irqstate_t ret;
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ret = up_irq_save();
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int me = this_cpu();
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if (0 == g_irq_spin_count[me])
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{
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spin_lock(&g_irq_spin);
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}
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g_irq_spin_count[me]++;
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DEBUGASSERT(0 != g_irq_spin_count[me]);
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return ret;
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}
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/****************************************************************************
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* Name: spin_unlock_irqrestore
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*
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* Description:
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* If SMP and SPINLOCK_IRQ are enabled:
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* Decrement the call counter (g_irq_spin_count[cpu]) and if it
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* decrements to zero then release the spinlock (g_irq_spin) and
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* restore the interrupt state as it was prior to the previous call to
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* spin_lock_irqsave().
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*
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* If SMP and SPINLOCK_IRQ are not enabled:
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* This function is equivalent to leave_critical_section().
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*
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* Input Parameters:
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* flags - The architecture-specific value that represents the state of
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* the interrupts prior to the call to spin_lock_irqsave();
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void spin_unlock_irqrestore(irqstate_t flags)
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{
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int me = this_cpu();
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DEBUGASSERT(0 < g_irq_spin_count[me]);
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g_irq_spin_count[me]--;
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if (0 == g_irq_spin_count[me])
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{
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spin_unlock(&g_irq_spin);
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}
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up_irq_restore(flags);
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}
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#endif /* CONFIG_SMP && CONFIG_SPINLOCK_IRQ */
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