nuttx/arch/arm/src/kinetis/kinetis_start.c

/****************************************************************************
 * arch/arm/src/kinetis/kinetis_start.c
 * arch/arm/src/chip/kinetis_start.c
 *
 *   Copyright (C) 2011-2012 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 <assert.h>
#include <debug.h>

#include <nuttx/init.h>
#include <arch/board/board.h>

#include "up_arch.h"
#include "up_internal.h"

#include "kinetis_internal.h"
#include "kinetis_smc.h"
#include "kinetis_userspace.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: _start
 *
 * Description:
 *   This is the reset entry point.
 *
 ****************************************************************************/

void __start(void)
{
  const uint32_t *src;
  uint32_t *dest;

  /* Disable the watchdog timer */

  kinetis_wddisable();

  /* Clear .bss.  We'll do this inline (vs. calling memset) just to be
   * certain that there are no issues with the state of global variables.
   */

  for (dest = &_sbss; dest < &_ebss; )
    {
      *dest++ = 0;
    }

  /* Move the initialized data section from his temporary holding spot in
   * FLASH into the correct place in SRAM.  The correct place in SRAM is
   * give by _sdata and _edata.  The temporary location is in FLASH at the
   * end of all of the other read-only data (.text, .rodata) at _eronly.
   */

  for (src = &_eronly, dest = &_sdata; dest < &_edata; )
    {
      *dest++ = *src++;
    }

  /* Copy any necessary code sections from FLASH to RAM.  The correct
   * destination in SRAM is given by _sramfuncs and _eramfuncs.  The
   * temporary location is in flash after the data initialization code
   * at _framfuncs
   */

#ifdef CONFIG_ARCH_RAMFUNCS
  for (src = &_framfuncs, dest = &_sramfuncs; dest < &_eramfuncs; )
    {
      *dest++ = *src++;
    }
#endif

  /* Perform clock and Kinetis module initialization (This depends on
   * RAM functions having been copied to RAM).
   */

  kinetis_clockconfig();

  /* Configure the uart and perform early serial initialization so that we
   * can get debug output as soon as possible (This depends on clock
   * configuration).
   */

  kinetis_lowsetup();
#ifdef USE_EARLYSERIALINIT
  up_earlyserialinit();
#endif

  /* For the case of the separate user-/kernel-space build, perform whatever
   * platform specific initialization of the user memory is required.
   * Normally this just means initializing the user space .data and .bss
   * segments.
   */

#ifdef CONFIG_BUILD_PROTECTED
  kinetis_userspace();
#endif

  /* Initialize other on-board resources */

  kinetis_boardinitialize();

  /* Show reset status */

  dbg("Reset status: %02x:%02x\n",
      getreg8(KINETIS_SMC_SRSH), getreg8(KINETIS_SMC_SRSL));

  /* Then start NuttX */

  os_start();

  /* Shouldn't get here */

  for (; ; );
}