150 lines
3.7 KiB
C
150 lines
3.7 KiB
C
/*
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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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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/module.h>
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#include "windfarm_pid.h"
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#undef DEBUG
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#ifdef DEBUG
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#define DBG(args...) printk(args)
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#else
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#define DBG(args...) do { } while(0)
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#endif
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void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param)
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{
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memset(st, 0, sizeof(struct wf_pid_state));
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st->param = *param;
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st->first = 1;
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}
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EXPORT_SYMBOL_GPL(wf_pid_init);
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s32 wf_pid_run(struct wf_pid_state *st, s32 new_sample)
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{
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s64 error, integ, deriv;
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s32 target;
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int i, hlen = st->param.history_len;
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/* Calculate error term */
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error = new_sample - st->param.itarget;
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/* Get samples into our history buffer */
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if (st->first) {
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for (i = 0; i < hlen; i++) {
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st->samples[i] = new_sample;
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st->errors[i] = error;
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}
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st->first = 0;
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st->index = 0;
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} else {
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st->index = (st->index + 1) % hlen;
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st->samples[st->index] = new_sample;
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st->errors[st->index] = error;
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}
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/* Calculate integral term */
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for (i = 0, integ = 0; i < hlen; i++)
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integ += st->errors[(st->index + hlen - i) % hlen];
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integ *= st->param.interval;
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/* Calculate derivative term */
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deriv = st->errors[st->index] -
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st->errors[(st->index + hlen - 1) % hlen];
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deriv /= st->param.interval;
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/* Calculate target */
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target = (s32)((integ * (s64)st->param.gr + deriv * (s64)st->param.gd +
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error * (s64)st->param.gp) >> 36);
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if (st->param.additive)
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target += st->target;
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target = max(target, st->param.min);
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target = min(target, st->param.max);
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st->target = target;
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return st->target;
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}
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EXPORT_SYMBOL_GPL(wf_pid_run);
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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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{
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memset(st, 0, sizeof(struct wf_cpu_pid_state));
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st->param = *param;
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st->first = 1;
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}
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EXPORT_SYMBOL_GPL(wf_cpu_pid_init);
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s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 new_power, s32 new_temp)
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{
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s64 integ, deriv, prop;
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s32 error, target, sval, adj;
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int i, hlen = st->param.history_len;
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/* Calculate error term */
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error = st->param.pmaxadj - new_power;
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/* Get samples into our history buffer */
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if (st->first) {
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for (i = 0; i < hlen; i++) {
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st->powers[i] = new_power;
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st->errors[i] = error;
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}
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st->temps[0] = st->temps[1] = new_temp;
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st->first = 0;
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st->index = st->tindex = 0;
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} else {
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st->index = (st->index + 1) % hlen;
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st->powers[st->index] = new_power;
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st->errors[st->index] = error;
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st->tindex = (st->tindex + 1) % 2;
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st->temps[st->tindex] = new_temp;
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}
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/* Calculate integral term */
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for (i = 0, integ = 0; i < hlen; i++)
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integ += st->errors[(st->index + hlen - i) % hlen];
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integ *= st->param.interval;
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integ *= st->param.gr;
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sval = st->param.tmax - (s32)(integ >> 20);
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adj = min(st->param.ttarget, sval);
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DBG("integ: %lx, sval: %lx, adj: %lx\n", integ, sval, adj);
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/* Calculate derivative term */
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deriv = st->temps[st->tindex] -
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st->temps[(st->tindex + 2 - 1) % 2];
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deriv /= st->param.interval;
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deriv *= st->param.gd;
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/* Calculate proportional term */
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prop = st->last_delta = (new_temp - adj);
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prop *= st->param.gp;
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DBG("deriv: %lx, prop: %lx\n", deriv, prop);
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/* Calculate target */
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target = st->target + (s32)((deriv + prop) >> 36);
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target = max(target, st->param.min);
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target = min(target, st->param.max);
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st->target = target;
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return st->target;
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}
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EXPORT_SYMBOL_GPL(wf_cpu_pid_run);
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MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
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MODULE_DESCRIPTION("PID algorithm for PowerMacs thermal control");
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MODULE_LICENSE("GPL");
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