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Diffstat (limited to 'nuttx/drivers/power/pm_checkstate.c')
-rw-r--r-- | nuttx/drivers/power/pm_checkstate.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/nuttx/drivers/power/pm_checkstate.c b/nuttx/drivers/power/pm_checkstate.c new file mode 100644 index 000000000..9b0e1045e --- /dev/null +++ b/nuttx/drivers/power/pm_checkstate.c @@ -0,0 +1,161 @@ +/**************************************************************************** + * drivers/power/pm_checkstate.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 <nuttx/clock.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 + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: pm_checkstate + * + * Description: + * This function is called from the MCU-specific IDLE loop to monitor the + * the power management conditions. This function returns the "recommended" + * power management state based on the PM configuration and activity + * reported in the last sampling periods. The power management state is + * not automatically changed, however. The IDLE loop must call + * pm_changestate() in order to make the state change. + * + * These two steps are separated because the plaform-specific IDLE loop may + * have additional situational information that is not available to the + * the PM sub-system. For example, the IDLE loop may know that the + * battery charge level is very low and may force lower power states + * even if there is activity. + * + * NOTE: That these two steps are separated in time and, hence, the IDLE + * loop could be suspended for a long period of time between calling + * pm_checkstate() and pm_changestate(). The IDLE loop may need to make + * these calls atomic by either disabling interrupts until the state change + * is completed. + * + * Input Parameters: + * None + * + * Returned Value: + * The recommended power management state. + * + ****************************************************************************/ + +enum pm_state_e pm_checkstate(void) +{ + uint32_t now; + irqstate_t flags; + + /* Check for the end of the current time slice. This must be performed + * with interrupts disabled so that it does not conflict with the similar + * logic in pm_activity(). + */ + + flags = irqsave(); + + /* Check the elapsed time. In periods of low activity, time slicing is + * controlled by IDLE loop polling; in periods of higher activity, time + * slicing is controlled by driver activity. In either case, the duration + * of the time slice is only approximate; during times of heavy activity, + * time slices may be become longer and the activity level may be over- + * estimated. + */ + + now = clock_systimer(); + if (now - g_pmglobals.stime >= TIME_SLICE_TICKS) + { + int16_t accum; + + /* Sample the count, reset the time and count, and assess the PM + * state. This is an atomic operation because interrupts are + * still disabled. + */ + + accum = g_pmglobals.accum; + g_pmglobals.stime = now; + g_pmglobals.accum = 0; + + /* Reassessing the PM state may require some computation. However, + * the work will actually be performed on a worker thread at a user- + * controlled priority. + */ + + (void)pm_update(accum); + } + irqrestore(flags); + + /* Return the recommended state. Assuming that we are called from the + * IDLE thread at the lowest priority level, any updates scheduled on the + * worker thread above should have already been peformed and the recommended + * state should be current: + */ + + return g_pmglobals.recommended; +} + +#endif /* CONFIG_PM */ |