text: /****************************************************************************
   * arch/xtensa/src/esp32/esp32_idle.c
   *
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.  The
   * ASF licenses this file to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance with the
   * License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations
   * under the License.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  #include <nuttx/irq.h>
  #include <nuttx/arch.h>
  #include <nuttx/power/pm.h>
  
  #include "esp32_pm.h"
  #include "xtensa.h"
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /* Values for the RTC Alarm to wake up from the PM_STANDBY mode
   * (which corresponds to ESP32 stop mode).  If this alarm expires,
   * the logic in this file will wakeup from PM_STANDBY mode and
   * transition to PM_SLEEP mode (ESP32 standby mode).
   */
  
  #ifdef CONFIG_PM
  #ifndef CONFIG_PM_ALARM_SEC
  #  define CONFIG_PM_ALARM_SEC 15
  #endif
  
  #ifndef CONFIG_PM_ALARM_NSEC
  #  define CONFIG_PM_ALARM_NSEC 0
  #endif
  
  #define PM_IDLE_DOMAIN 0 /* Revisit */
  #endif
  
  /****************************************************************************
   * 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 = spin_lock_irqsave();
  
        /* 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 */
  
            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:
            {
              /* Configure the RTC alarm to Auto Wake the system */
  
              esp32_pmstart(CONFIG_PM_ALARM_SEC * 1000000 +
                                    CONFIG_PM_ALARM_NSEC / 1000);
  
              /* Resume normal operation */
  
              pm_relax(PM_IDLE_DOMAIN, PM_STANDBY);
            }
            break;
  
          case PM_SLEEP:
            {
              pm_changestate(PM_IDLE_DOMAIN, PM_NORMAL);
              newstate = PM_NORMAL;
            }
            break;
  
          default:
            break;
          }
  
        spin_unlock_irqrestore(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.
     */
  
    nxsched_process_timer();
  #else
  
    /* Perform IDLE mode power management */
  
    up_idlepm();
  
    /* This would be an appropriate place to put some MCU-specific logic to
     * sleep in a reduced power mode until an interrupt occurs to save power
     */
  
  #if XCHAL_HAVE_INTERRUPTS
    __asm__ __volatile__ ("waiti 0");
  #endif
  #endif
  }
  