text: /****************************************************************************
   *  arch/arm/src/samdl/sam_idle.c
   *
   *   Copyright (C) 2014, 2015-2016 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 <arch/board/board.h>
  #include <nuttx/config.h>
  
  #include <nuttx/arch.h>
  #include <nuttx/board.h>
  #include <nuttx/power/pm.h>
  
  #include <nuttx/irq.h>
  
  #include "chip.h"
  #include "up_internal.h"
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /* Does the board support an IDLE LED to indicate that the board is in the
   * IDLE state?
   */
  
  #if defined(CONFIG_ARCH_LEDS) && defined(LED_IDLE)
  #  define BEGIN_IDLE() board_autoled_on(LED_IDLE)
  #  define END_IDLE()   board_autoled_off(LED_IDLE)
  #else
  #  define BEGIN_IDLE()
  #  define END_IDLE()
  #endif
  
  #define PM_IDLE_DOMAIN 0 /* Revisit */
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_idlepm
   *
   * Description:
   *   Perform IDLE state power management.
   *
   ****************************************************************************/
  
  #ifdef CONFIG_PM
  static void up_idlepm(void)
  {
    static enum pm_state_e oldstate = PM_NORMAL;
    enum pm_state_e newstate;
    irqstate_t flags;
    int ret;
  
    /* Decide, which power saving level can be obtained */
  
    newstate = pm_checkstate(PM_IDLE_DOMAIN);
  
    /* Check for state changes */
  
    if (newstate != oldstate)
      {
        flags = enter_critical_section();
  
        /* Perform board-specific, state-dependent logic here */
  
        _info("newstate= %d oldstate=%d\n", newstate, oldstate);
  
        /* Then force the global state change */
  
        ret = pm_changestate(PM_IDLE_DOMAIN, newstate);
        if (ret < 0)
          {
            /* The new state change failed, revert to the preceding state */
  
            (void)pm_changestate(PM_IDLE_DOMAIN, oldstate);
          }
        else
          {
            /* Save the new state */
  
            oldstate = newstate;
          }
  
        /* MCU-specific power management logic */
  
        switch (newstate)
          {
          case PM_NORMAL:
            break;
  
          case PM_IDLE:
            break;
  
          case PM_STANDBY:
            sam_pmstop(true);
            break;
  
          case PM_SLEEP:
            (void)sam_pmstandby();
            break;
  
          default:
            break;
          }
  
        leave_critical_section(flags);
      }
  }
  #else
  #  define up_idlepm()
  #endif
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_idle
   *
   * Description:
   *   up_idle() is the logic that will be executed when their is no other
   *   ready-to-run task.  This is processor idle time and will continue until
   *   some interrupt occurs to cause a context switch from the idle task.
   *
   *   Processing in this state may be processor-specific. e.g., this is where
   *   power management operations might be performed.
   *
   ****************************************************************************/
  
  void up_idle(void)
  {
  #if defined(CONFIG_SUPPRESS_INTERRUPTS) || defined(CONFIG_SUPPRESS_TIMER_INTS)
    /* If the system is idle and there are no timer interrupts, then process
     * "fake" timer interrupts. Hopefully, something will wake up.
     */
  
    sched_process_timer();
  #else
  
    /* Perform IDLE mode power management */
  
    up_idlepm();
  
    /* Sleep until an interrupt occurs to save power. */
  
    BEGIN_IDLE();
    asm("WFI");
    END_IDLE();
  #endif
  }
  