Add xtensa_testset.c
This commit is contained in:
Gregory Nutt
parent
fb7b545637
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29c3acdc4e
@ -82,7 +82,7 @@ typedef uint8_t spinlock_t;
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* Name: up_testset
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*
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* Description:
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* Perform and atomic test and set operation on the provided spinlock.
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* Perform an atomic test and set operation on the provided spinlock.
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*
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* This function must be provided via the architecture-specific logoic.
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*
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@ -71,14 +71,6 @@
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#define STACK_ALIGN_DOWN(a) ((a) & ~STACK_ALIGN_MASK)
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#define STACK_ALIGN_UP(a) (((a) + STACK_ALIGN_MASK) & ~STACK_ALIGN_MASK)
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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141
arch/xtensa/src/common/xtensa_testset.c
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141
arch/xtensa/src/common/xtensa_testset.c
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@ -0,0 +1,141 @@
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/****************************************************************************
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* arch/xtensa/src/common/xtensa_testset.c
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*
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* Copyright (C) 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <spinlock.h>
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#include <arch/spinlock.h>
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#include "xtensa.h"
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#ifdef CONFIG_SPINLOCK
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: xtensa_compareset
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*
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* Description:
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* Wrapper for the Xtensa compare-and-set instruction. This function will
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* atomically compare *addr to compare, and if it's the same, will set
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* *addr to set. It will return the old value of *addr.
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*
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* Warning: From the ISA docs: in some (unspecified) cases, the s32c1i
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* instruction may return the *bitwise inverse* of the old mem if the
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* mem wasn't written. This doesn't seem to happen on the ESP32, though.
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* (Would show up directly if it did because the magic wouldn't match.)
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*
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****************************************************************************/
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static inline uint32_t xtensa_compareset(FAR volatile uint32_t *addr,
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uint32_t compare,
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uint32_t set)
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{
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__asm__ __volatile__
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(
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"WSR %2, SCOMPARE1\n" /* Initialize SCOMPARE1 */
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"ISYNC\n" /* Wait sync */
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"S32C1I %0, %1, 0\n" /* Store id into the lock, if the lock is the
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* same as comparel. Otherwise, no write-access */
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: "=r"(set) : "r"(addr), "r"(compare), "0"(set)
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);
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return set;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_testset
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*
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* Description:
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* Perform an atomic test and set operation on the provided spinlock.
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*
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* This function must be provided via the architecture-specific logoic.
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*
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* Input Parameters:
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* lock - The address of spinlock object.
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*
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* Returned Value:
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* The spinlock is always locked upon return. The value of previous value
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* of the spinlock variable is returned, either SP_LOCKED if the spinlock
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* was previously locked (meaning that the test-and-set operation failed to
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* obtain the lock) or SP_UNLOCKED if the spinlock was previously unlocked
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* (meaning that we successfully obtained the lock)
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*
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****************************************************************************/
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spinlock_t up_testset(volatile FAR spinlock_t *lock)
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{
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spinlock_t prev;
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/* Perform the 32-bit compare and set operation */
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prev = xtensa_compareset((FAR volatile uint32_t *)lock,
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SP_UNLOCKED, SP_LOCKED);
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/* xtensa_compareset() should return either SP_UNLOCKED if the spinlock
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* was locked or SP_LOCKED or possibly ~SP_UNLOCKED if the spinlock was
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* not locked:
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*
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* "In the RE-2013.0 release and after, there is a slight change in the
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* semantics of the S32C1I instruction. Nothing is changed about the
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* operation on memory. In rare cases the resulting value in register
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* at can be different in this and later releases. The rule still holds
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* that memory has been written if and only if the register result
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* equals SCOMPARE1.
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*
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* "The difference is that in some cases where memory has not been
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* written, the instruction returns ~SCOMPARE1 instead of the current
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* value of memory. Although this change can, in principle, affect
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* the operation of code, scanning all internal Cadence code produced
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* no examples where this change would change the operation of the
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* code."
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*
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* In any case, the return value of SP_UNLOCKED can be trusted and will
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* always mean that the the spinlock was set.
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*/
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return (prev == SP_UNLOCKED) ? SP_UNLOCKED : SP_LOCKED;
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}
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@ -69,14 +69,6 @@
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#define STACK_ALIGN_DOWN(a) ((a) & ~STACK_ALIGN_MASK)
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#define STACK_ALIGN_UP(a) (((a) + STACK_ALIGN_MASK) & ~STACK_ALIGN_MASK)
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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@ -55,6 +55,9 @@ ifeq ($(CONFIG_DEBUG_ALERT),y)
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CMN_CSRCS += xtensa_dumpstate.c
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endif
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ifeq ($(CONFIG_SPINLOCK),y)
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CMN_CSRCS += xtensa_testset.c
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endif
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# Use of common/xtensa_etherstub.c is deprecated. The preferred mechanism
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# is to use CONFIG_NETDEV_LATEINIT=y to suppress the call to
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@ -83,7 +83,7 @@ struct spinlock_s
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* Name: up_testset
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*
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* Description:
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* Perform and atomic test and set operation on the provided spinlock.
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* Perform an atomic test and set operation on the provided spinlock.
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*
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* This function must be provided via the architecture-specific logoic.
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*
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