86 lines
2.7 KiB
C
86 lines
2.7 KiB
C
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/*
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* Windfarm PowerMac thermal control. Generic PID helpers
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*
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* (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
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* <benh@kernel.crashing.org>
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*
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* Released under the term of the GNU GPL v2.
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*
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* This is a pair of generic PID helpers that can be used by
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* control loops. One is the basic PID implementation, the
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* other one is more specifically tailored to the loops used
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* for CPU control with 2 input sample types (temp and power)
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*/
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/*
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* *** Simple PID ***
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*/
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#define WF_PID_MAX_HISTORY 32
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/* This parameter array is passed to the PID algorithm. Currently,
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* we don't support changing parameters on the fly as it's not needed
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* but could be implemented (with necessary adjustment of the history
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* buffer
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*/
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struct wf_pid_param {
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int interval; /* Interval between samples in seconds */
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int history_len; /* Size of history buffer */
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int additive; /* 1: target relative to previous value */
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s32 gd, gp, gr; /* PID gains */
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s32 itarget; /* PID input target */
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s32 min,max; /* min and max target values */
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};
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struct wf_pid_state {
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int first; /* first run of the loop */
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int index; /* index of current sample */
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s32 target; /* current target value */
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s32 samples[WF_PID_MAX_HISTORY]; /* samples history buffer */
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s32 errors[WF_PID_MAX_HISTORY]; /* error history buffer */
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struct wf_pid_param param;
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};
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extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
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extern s32 wf_pid_run(struct wf_pid_state *st, s32 sample);
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/*
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* *** CPU PID ***
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*/
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#define WF_CPU_PID_MAX_HISTORY 32
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/* This parameter array is passed to the CPU PID algorithm. Currently,
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* we don't support changing parameters on the fly as it's not needed
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* but could be implemented (with necessary adjustment of the history
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* buffer
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*/
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struct wf_cpu_pid_param {
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int interval; /* Interval between samples in seconds */
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int history_len; /* Size of history buffer */
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s32 gd, gp, gr; /* PID gains */
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s32 pmaxadj; /* PID max power adjust */
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s32 ttarget; /* PID input target */
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s32 tmax; /* PID input max */
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s32 min,max; /* min and max target values */
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};
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struct wf_cpu_pid_state {
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int first; /* first run of the loop */
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int index; /* index of current power */
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int tindex; /* index of current temp */
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s32 target; /* current target value */
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s32 last_delta; /* last Tactual - Ttarget */
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s32 powers[WF_PID_MAX_HISTORY]; /* power history buffer */
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s32 errors[WF_PID_MAX_HISTORY]; /* error history buffer */
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s32 temps[2]; /* temp. history buffer */
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struct wf_cpu_pid_param param;
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};
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extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
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struct wf_cpu_pid_param *param);
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extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);
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