nuttx/arch/arm/src/armv7-a/arm_initialstate.c

141 lines
4.9 KiB
C

/****************************************************************************
* arch/arm/src/armv7-a/arm_initialstate.c
*
* Copyright (C) 2013-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <string.h>
#include <nuttx/arch.h>
#include "arm.h"
#include "up_internal.h"
#include "up_arch.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_initial_state
*
* Description:
* A new thread is being started and a new TCB has been created. This
* function is called to initialize the processor specific portions of
* the new TCB.
*
* This function must setup the initial architecture registers and/or
* stack so that execution will begin at tcb->start on the next context
* switch.
*
****************************************************************************/
void up_initial_state(struct tcb_s *tcb)
{
struct xcptcontext *xcp = &tcb->xcp;
uint32_t cpsr;
/* Initialize the initial exception register context structure */
memset(xcp, 0, sizeof(struct xcptcontext));
/* Save the initial stack pointer */
xcp->regs[REG_SP] = (uint32_t)tcb->adj_stack_ptr;
/* Save the task entry point */
xcp->regs[REG_PC] = (uint32_t)tcb->start;
/* If this task is running PIC, then set the PIC base register to the
* address of the allocated D-Space region.
*/
#ifdef CONFIG_PIC
if (tcb->dspace != NULL)
{
/* Set the PIC base register (probably R10) to the address of the
* alloacated D-Space region.
*/
xcp->regs[REG_PIC] = (uint32_t)tcb->dspace->region;
}
#endif
/* Set supervisor-mode and disable FIQs, regardless of how NuttX is
* configured and of what kind of thread is being started. That is
* because all threads, even user-mode threads will start in kernel
* trampoline at task_start() or pthread_start(). The thread's
* privileges will be dropped before transitioning to user code.
*/
cpsr = PSR_MODE_SVC;
/* Enable or disable interrupts, based on user configuration */
#ifdef CONFIG_SUPPRESS_INTERRUPTS
/* Disable interrupts (both IRQs and FIQs) */
cpsr |= (PSR_I_BIT | PSR_F_BIT);
#else /* CONFIG_SUPPRESS_INTERRUPTS */
/* Leave IRQs enabled (Also FIQs if CONFIG_ARMV7A_DECODEFIQ is selected) */
#ifndef CONFIG_ARMV7A_DECODEFIQ
cpsr |= PSR_F_BIT;
#endif /* !CONFIG_ARMV7A_DECODEFIQ */
#endif /* CONFIG_SUPPRESS_INTERRUPTS */
xcp->regs[REG_CPSR] = cpsr;
}