152 lines
5.1 KiB
C
152 lines
5.1 KiB
C
/* nanocontext.c - new context creation for ARM Cortex-M */
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/*
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* Copyright (c) 2013-2014 Wind River Systems, Inc.
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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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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN 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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DESCRIPTION
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Core nanokernel fiber related primitives for the ARM Cortex-M processor
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architecture.
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*/
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#include <nanokernel.h>
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#include <nanokernel/cpu.h>
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#include <toolchain.h>
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#include <nanok.h>
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#include <nanocontextentry.h>
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tNANO _NanoKernel = {0};
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#if defined(CONFIG_HOST_TOOLS_SUPPORT)
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#define TOOLS_SUPPORT_INIT(pCcs) toolsSupportInit(pCcs)
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#else
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#define TOOLS_SUPPORT_INIT(pCcs) \
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do {/* do nothing */ \
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} while ((0))
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#endif
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#if defined(CONFIG_HOST_TOOLS_SUPPORT)
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/*******************************************************************************
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*
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* toolsSupportInit - initialize host-tools support when needed
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*
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* Currently only inserts the new context in the list of active contexts.
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*
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* RETURNS: N/A
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*/
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static ALWAYS_INLINE void toolsSupportInit(struct s_CCS *pCcs /* context */
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)
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{
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unsigned int key;
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/*
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* Add the newly initialized context to head of the list of contexts.
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* This singly linked list of contexts maintains ALL the contexts in the
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* system: both tasks and fibers regardless of whether they are
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* runnable.
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*/
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key = irq_lock();
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pCcs->activeLink = _NanoKernel.contexts;
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_NanoKernel.contexts = pCcs;
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irq_unlock(key);
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}
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#endif /* CONFIG_HOST_TOOLS_SUPPORT */
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/*******************************************************************************
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*
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* _NewContext - intialize a new context (thread) from its stack space
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*
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* The control structure (CCS) is put at the lower address of the stack. An
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* initial context, to be "restored" by __pendsv(), is put at the other end of
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* the stack, and thus reusable by the stack when not needed anymore.
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*
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* The initial context is an exception stack frame (ESF) since exiting the
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* PendSV exception will want to pop an ESF. Interestingly, even if the lsb of
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* an instruction address to jump to must always be set since the CPU always
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* runs in thumb mode, the ESF expects the real address of the instruction,
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* with the lsb *not* set (instructions are always aligned on 16 bit halfwords).
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* Since the compiler automatically sets the lsb of function addresses, we have
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* to unset it manually before storing it in the 'pc' field of the ESF.
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*
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* <options> is currently unused.
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*
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* RETURNS: N/A
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*/
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void *_NewContext(
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char *pStackMem, /* stack memory */
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unsigned stackSize, /* stack size in bytes */
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_ContextEntry pEntry, /* entry point */
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void *parameter1, /* entry point first param */
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void *parameter2, /* entry point second param */
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void *parameter3, /* entry point third param */
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int priority, /* context priority (-1 for tasks) */
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unsigned options /* misc options (future) */
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)
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{
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char *stackEnd = pStackMem + stackSize;
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struct __esf *pInitCtx;
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tCCS *pCcs = (void *)ROUND_UP(pStackMem, sizeof(uint32_t));
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/* carve the context entry struct from the "base" of the stack */
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pInitCtx = (struct __esf *)(STACK_ROUND_DOWN(stackEnd) -
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sizeof(struct __esf));
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pInitCtx->pc = ((uint32_t)_ContextEntryRtn) & 0xfffffffe;
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pInitCtx->a1 = (uint32_t)pEntry;
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pInitCtx->a2 = (uint32_t)parameter1;
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pInitCtx->a3 = (uint32_t)parameter2;
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pInitCtx->a4 = (uint32_t)parameter3;
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pInitCtx->xpsr =
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0x01000000UL; /* clear all, thumb bit is 1, even if RO */
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pCcs->link = NULL;
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pCcs->flags = priority == -1 ? TASK | PREEMPTIBLE : FIBER;
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pCcs->prio = priority;
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#ifdef CONFIG_CONTEXT_CUSTOM_DATA
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/* Initialize custom data field (value is opaque to kernel) */
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pCcs->custom_data = NULL;
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#endif
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pCcs->preempReg.psp = (uint32_t)pInitCtx;
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pCcs->basepri = 0;
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/* initial values in all other registers/CCS entries are irrelevant */
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TOOLS_SUPPORT_INIT(pCcs);
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return pCcs;
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}
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