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/****************************************************************************
* drivers/power/pm_changestate.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 <nuttx/power/pm.h>
#include <arch/irq.h>
#include "pm_internal.h"
#ifdef CONFIG_PM
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: pm_prepall
*
* Description:
* Prepare every driver for the state change.
*
* Input Parameters:
* newstate - Identifies the new PM state
*
* Returned Value:
* 0 (OK) means that the callback function for all registered drivers
* returned OK (meaning that they accept the state change). Non-zero
* means that one of the drivers refused the state change. In this case,
* the system will revert to the preceding state.
*
* Assumptions:
* Interrupts are disabled.
*
****************************************************************************/
static int pm_prepall(enum pm_state_e newstate)
{
FAR sq_entry_t *entry;
int ret = OK;
/* Visit each registered callback structure. */
for (entry = sq_peek(&g_pmglobals.registry);
entry && ret == OK;
entry = sq_next(entry))
{
/* Is the prepare callback supported? */
FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
if (cb->prepare)
{
/* Yes.. prepare the driver */
ret = cb->prepare(cb, newstate);
}
}
return ret;
}
/****************************************************************************
* Name: pm_changeall
*
* Description:
* Inform all drivers of the state change.
*
* Input Parameters:
* newstate - Identifies the new PM state
*
* Returned Value:
* None
*
* Assumptions:
* Interrupts are disabled.
*
****************************************************************************/
static inline void pm_changeall(enum pm_state_e newstate)
{
FAR sq_entry_t *entry;
/* Visit each registered callback structure. */
for (entry = sq_peek(&g_pmglobals.registry); entry; entry = sq_next(entry))
{
/* Is the notification callback supported? */
FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
if (cb->notify)
{
/* Yes.. notify the driver */
cb->notify(cb, newstate);
}
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pm_changestate
*
* Description:
* This function is used by platform-specific power management logic. It
* will announce the power management power management state change to all
* drivers that have registered for power management event callbacks.
*
* Input Parameters:
* newstate - Identifies the new PM state
*
* Returned Value:
* 0 (OK) means that the callback function for all registered drivers
* returned OK (meaning that they accept the state change). Non-zero
* means that one of the drivers refused the state change. In this case,
* the system will revert to the preceding state.
*
* Assumptions:
* It is assumed that interrupts are disabled when this function is
* called. This function is probably called from the IDLE loop... the
* lowest priority task in the system. Changing driver power management
* states may result in renewed system activity and, as a result, can
* suspend the IDLE thread before it completes the entire state change
* unless interrupts are disabled throughout the state change.
*
****************************************************************************/
int pm_changestate(enum pm_state_e newstate)
{
irqstate_t flags;
int ret;
/* Disable interrupts throught this operation... changing driver states
* could cause additional driver activity that might interfere with the
* state change. When the state change is complete, interrupts will be
* re-enabled.
*/
flags = irqsave();
/* First, prepare the drivers for the state change. In this phase,
* drivers may refuse the state state change.
*/
ret = pm_prepall(newstate);
if (ret != OK)
{
/* One or more drivers is not ready for this state change. Revert to
* the preceding state.
*/
newstate = g_pmglobals.state;
(void)pm_prepall(newstate);
}
/* All drivers have agreed to the state change (or, one or more have
* disagreed and the state has been reverted). Set the new state.
*/
pm_changeall(newstate);
g_pmglobals.state = newstate;
/* Restore the interrupt state */
irqrestore(flags);
return ret;
}
#endif /* CONFIG_PM */
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