/**************************************************************************** * drivers/power/pm_update.c * * Copyright (C) 2011-2012 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include "pm.h" #ifdef CONFIG_PM /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Function Prototypes ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /* CONFIG_PM_MEMORY is the total number of time slices (including the current * time slice. The histor or previous values is then CONFIG_PM_MEMORY-1. */ #if CONFIG_PM_MEMORY > 1 static const int16_t g_pmcoeffs[CONFIG_PM_MEMORY-1] = { CONFIG_PM_COEF1 #if CONFIG_PM_MEMORY > 2 , CONFIG_PM_COEF2 #endif #if CONFIG_PM_MEMORY > 3 , CONFIG_PM_COEF3 #endif #if CONFIG_PM_MEMORY > 4 , CONFIG_PM_COEF4 #endif #if CONFIG_PM_MEMORY > 5 , CONFIG_PM_COEF5 #endif #if CONFIG_PM_MEMORY > 6 # warning "This logic needs to be extended" #endif }; #endif /* Threshold activity values to enter into the next lower power consumption * state. Indexing is next state 0:IDLE, 1:STANDBY, 2:SLEEP. */ static const int16_t g_pmenterthresh[3] = { CONFIG_PM_IDLEENTER_THRESH, CONFIG_PM_STANDBYENTER_THRESH, CONFIG_PM_SLEEPENTER_THRESH }; /* Threshold activity values to leave the current low power consdumption * state. Indexing is current state 0:IDLE, 1: STANDBY, 2: SLEEP. */ static const int16_t g_pmexitthresh[3] = { CONFIG_PM_IDLEEXIT_THRESH, CONFIG_PM_STANDBYEXIT_THRESH, CONFIG_PM_SLEEPEXIT_THRESH }; /* Threshold time slice count to enter the next low power consdumption * state. Indexing is next state 0:IDLE, 1: STANDBY, 2: SLEEP. */ static const uint16_t g_pmcount[3] = { CONFIG_PM_IDLEENTER_COUNT, CONFIG_PM_STANDBYENTER_COUNT, CONFIG_PM_SLEEPENTER_COUNT }; /**************************************************************************** * Public Data ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: pm_worker * * Description: * This worker function is queue at the end of a time slice in order to * update driver activity metrics and recommended states. * * Input Parameters: * arg - The value of the activity accumulator at the end of the time * slice. * * Returned Value: * None. * * Assumptions: * This function runs on the worker thread. * ****************************************************************************/ void pm_worker(FAR void *arg) { int16_t accum = (int16_t)((intptr_t)arg); int32_t Y; int index; #if CONFIG_PM_MEMORY > 1 int32_t denom; int i, j; /* We won't bother to do anything until we have accumulated * CONFIG_PM_MEMORY-1 samples. */ if (g_pmglobals.mcnt < CONFIG_PM_MEMORY-1) { g_pmglobals.memory[g_pmglobals.mcnt] = accum; g_pmglobals.mcnt++; return; } /* The averaging algorithm is simply: Y = (An*X + SUM(Ai*Yi))/SUM(Aj), where * i = 1..n-1 and j= 1..n, n is the length of the "memory", Ai is the * weight applied to each value, and X is the current activity. * * CONFIG_PM_MEMORY provides the memory for the algorithm. Default: 2 * CONFIG_PM_COEFn provides weight for each sample. Default: 1 * * First, calclate Y = An*X */ Y = CONFIG_PM_COEFN * accum; denom = CONFIG_PM_COEFN; /* Then calculate Y += SUM(Ai*Yi), i = 1..n-1. The oldest sample will * reside at g_pmglobals.mndx (and this is the value that we will overwrite * with the new value). */ for (i = 0, j = g_pmglobals.mndx; i < CONFIG_PM_MEMORY-1; i++, j++) { if (j >= CONFIG_PM_MEMORY-1) { j = 0; } Y += g_pmcoeffs[i] * g_pmglobals.memory[j]; denom += g_pmcoeffs[i]; } /* Compute and save the new activity value */ Y /= denom; g_pmglobals.memory[g_pmglobals.mndx] = Y; g_pmglobals.mndx++; if (g_pmglobals.mndx >= CONFIG_PM_MEMORY-1) { g_pmglobals.mndx = 0; } #else /* No smoothing */ Y = accum; #endif /* First check if increased activity should cause us to return to the * normal operating state. This would be unlikely for the lowest power * consumption states because the CPU is probably asleep. However this * probably does apply for the IDLE state. */ if (g_pmglobals.state > PM_NORMAL) { /* Get the table index for the current state (which will be the * current state minus one) */ index = g_pmglobals.state - 1; /* Has the threshold to return to normal power consumption state been * exceeded? */ if (Y > g_pmexitthresh[index]) { /* Yes... reset the count and recommend the normal state. */ g_pmglobals.thrcnt = 0; g_pmglobals.recommended = PM_NORMAL; return; } } /* Now, compare this new activity level to the thresholds and counts for * the next lower power consumption state. If we are already in the SLEEP * state, then there is nothing more to be done (in fact, I would be * surprised to be executing!). */ if (g_pmglobals.state < PM_SLEEP) { unsigned int nextstate; /* Get the next state and the table index for the next state (which will * be the current state) */ index = g_pmglobals.state; nextstate = g_pmglobals.state + 1; /* Has the threshold to enter the next lower power consumption state * been exceeded? */ if (Y > g_pmenterthresh[index]) { /* No... reset the count and recommend the current state */ g_pmglobals.thrcnt = 0; g_pmglobals.recommended = g_pmglobals.state; } /* Yes.. have we already recommended this state? If so, do nothing */ else if (g_pmglobals.recommended < nextstate) { /* No.. increment the count. Has it passed the count required * for a state transition? */ if (++g_pmglobals.thrcnt >= g_pmcount[index]) { /* Yes, recommend the new state and set up for the next * transition. */ g_pmglobals.thrcnt = 0; g_pmglobals.recommended = nextstate; } } } } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: pm_update * * Description: * This internal function is called at the end of a time slice in order to * update driver activity metrics and recommended states. * * Input Parameters: * accum - The value of the activity accumulator at the end of the time * slice. * * Returned Value: * None. * * Assumptions: * This function may be called from a driver, perhaps even at the interrupt * level. It may also be called from the IDLE loop at the lowest possible * priority level. To reconcile these various conditions, all work is * performed on the worker thread at a user-selectable priority. This will * also serialize all of the updates and eliminate any need for additional * protection. * ****************************************************************************/ void pm_update(int16_t accum) { /* The work will be performed on the worker thread */ DEBUGASSERT(g_pmglobals.work.worker == NULL); (void)work_queue(HPWORK, &g_pmglobals.work, pm_worker, (FAR void *)((intptr_t)accum), 0); } #endif /* CONFIG_PM */