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161 lines
6.3 KiB
161 lines
6.3 KiB
/**************************************************************************** |
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* drivers/power/pm_checkstate.c |
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* |
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* Copyright (C) 2011-2012 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**************************************************************************** |
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* Included Files |
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****************************************************************************/ |
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#include <nuttx/config.h> |
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#include <nuttx/power/pm.h> |
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#include <nuttx/clock.h> |
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#include <arch/irq.h> |
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#include "pm_internal.h" |
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#ifdef CONFIG_PM |
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/**************************************************************************** |
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* Pre-processor Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Types |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Function Prototypes |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Name: pm_checkstate |
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* |
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* Description: |
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* This function is called from the MCU-specific IDLE loop to monitor the |
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* the power management conditions. This function returns the "recommended" |
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* power management state based on the PM configuration and activity |
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* reported in the last sampling periods. The power management state is |
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* not automatically changed, however. The IDLE loop must call |
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* pm_changestate() in order to make the state change. |
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* |
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* These two steps are separated because the plaform-specific IDLE loop may |
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* have additional situational information that is not available to the |
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* the PM sub-system. For example, the IDLE loop may know that the |
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* battery charge level is very low and may force lower power states |
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* even if there is activity. |
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* |
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* NOTE: That these two steps are separated in time and, hence, the IDLE |
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* loop could be suspended for a long period of time between calling |
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* pm_checkstate() and pm_changestate(). The IDLE loop may need to make |
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* these calls atomic by either disabling interrupts until the state change |
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* is completed. |
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* |
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* Input Parameters: |
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* None |
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* |
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* Returned Value: |
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* The recommended power management state. |
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* |
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****************************************************************************/ |
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enum pm_state_e pm_checkstate(void) |
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{ |
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uint32_t now; |
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irqstate_t flags; |
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/* Check for the end of the current time slice. This must be performed |
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* with interrupts disabled so that it does not conflict with the similar |
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* logic in pm_activity(). |
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*/ |
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flags = irqsave(); |
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/* Check the elapsed time. In periods of low activity, time slicing is |
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* controlled by IDLE loop polling; in periods of higher activity, time |
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* slicing is controlled by driver activity. In either case, the duration |
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* of the time slice is only approximate; during times of heavy activity, |
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* time slices may be become longer and the activity level may be over- |
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* estimated. |
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*/ |
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now = clock_systimer(); |
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if (now - g_pmglobals.stime >= TIME_SLICE_TICKS) |
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{ |
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int16_t accum; |
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/* Sample the count, reset the time and count, and assess the PM |
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* state. This is an atomic operation because interrupts are |
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* still disabled. |
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*/ |
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accum = g_pmglobals.accum; |
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g_pmglobals.stime = now; |
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g_pmglobals.accum = 0; |
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/* Reassessing the PM state may require some computation. However, |
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* the work will actually be performed on a worker thread at a user- |
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* controlled priority. |
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*/ |
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(void)pm_update(accum); |
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} |
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irqrestore(flags); |
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/* Return the recommended state. Assuming that we are called from the |
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* IDLE thread at the lowest priority level, any updates scheduled on the |
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* worker thread above should have already been peformed and the recommended |
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* state should be current: |
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*/ |
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return g_pmglobals.recommended; |
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} |
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#endif /* CONFIG_PM */
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