arch/or1k/src/common/or1k_initialstate.c

/****************************************************************************
 * arch/or1k/src/common/or1k_initialstate.c
 *
 *   Copyright (C) 2018 Extent3D. All rights reserved.
 *   Author: Matt Thompson <matt@extent3d.com>
 *
 * 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 <sys/types.h>
#include <stdint.h>
#include <string.h>

#include <nuttx/arch.h>

#include "or1k_internal.h"

#include <arch/spr.h>

/****************************************************************************
 * 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 sr;

  /* Initialize the idle thread stack */

  if (tcb->pid == IDLE_PROCESS_ID)
    {
      tcb->stack_alloc_ptr = (void *)(g_idle_topstack -
                                      CONFIG_IDLETHREAD_STACKSIZE);
      tcb->stack_base_ptr  = tcb->stack_alloc_ptr;
      tcb->adj_stack_size  = CONFIG_IDLETHREAD_STACKSIZE;

#ifdef CONFIG_STACK_COLORATION
      /* If stack debug is enabled, then fill the stack with a
       * recognizable value that we can use later to test for high
       * water marks.
       */

      or1k_stack_color(tcb->stack_alloc_ptr, 0);
#endif /* CONFIG_STACK_COLORATION */
    }

  /* Initialize the initial exception register context structure */

  memset(xcp, 0, sizeof(struct xcptcontext));

  xcp->regs[REG_R1] = (uint32_t)tcb->stack_base_ptr +
                                tcb->adj_stack_size;
  xcp->regs[REG_PC] = (uint32_t)tcb->start;

  mfspr(SPR_SYS_SR, sr);
  xcp->regs[REG_SR] = sr;

#ifdef CONFIG_NXFLAT
  /* Make certain that bit 0 is set in the main entry address.  This is
   * only an issue when NXFLAT is enabled.  NXFLAT doesn't know anything
   * about thumb; the addresses that NXFLAT sets are based on file header
   * info and won't have bit 0 set.
   */

  tcb->entry.main = (main_t)((uint32_t)tcb->entry.main | 1);
#endif

#ifdef CONFIG_BUILD_PROTECTED
  /* All tasks start via a stub function in kernel space.  So all
   * tasks must start in privileged thread mode.  If CONFIG_BUILD_PROTECTED
   * is defined, then that stub function will switch to unprivileged
   * mode before transferring control to the user task.
   */

  xcp->regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;
#endif

  /* Enable or disable interrupts, based on user configuration */

#ifdef CONFIG_SUPPRESS_INTERRUPTS
  xcp->regs[REG_PRIMASK] = 1;
#endif /* CONFIG_SUPPRESS_INTERRUPTS */
}