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Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 or later as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 6 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190520075211.856638608@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* pid.c PID controller for testing cooling devices
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*
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* Copyright (C) 2012 Intel Corporation. All rights reserved.
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*
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* Author Name Jacob Pan <jacob.jun.pan@linux.intel.com>
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <sys/types.h>
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#include <dirent.h>
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#include <libintl.h>
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#include <ctype.h>
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#include <assert.h>
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#include <time.h>
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#include <limits.h>
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#include <math.h>
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#include <sys/stat.h>
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#include <syslog.h>
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#include "tmon.h"
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/**************************************************************************
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* PID (Proportional-Integral-Derivative) controller is commonly used in
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* linear control system, consider the the process.
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* G(s) = U(s)/E(s)
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* kp = proportional gain
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* ki = integral gain
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* kd = derivative gain
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* Ts
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* We use type C Alan Bradley equation which takes set point off the
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* output dependency in P and D term.
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*
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* y[k] = y[k-1] - kp*(x[k] - x[k-1]) + Ki*Ts*e[k] - Kd*(x[k]
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* - 2*x[k-1]+x[k-2])/Ts
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*
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*
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***********************************************************************/
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struct pid_params p_param;
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/* cached data from previous loop */
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static double xk_1, xk_2; /* input temperature x[k-#] */
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/*
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* TODO: make PID parameters tuned automatically,
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* 1. use CPU burn to produce open loop unit step response
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* 2. calculate PID based on Ziegler-Nichols rule
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*
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* add a flag for tuning PID
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*/
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int init_thermal_controller(void)
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{
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int ret = 0;
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/* init pid params */
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p_param.ts = ticktime;
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/* TODO: get it from TUI tuning tab */
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p_param.kp = .36;
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p_param.ki = 5.0;
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p_param.kd = 0.19;
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p_param.t_target = target_temp_user;
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return ret;
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}
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void controller_reset(void)
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{
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/* TODO: relax control data when not over thermal limit */
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syslog(LOG_DEBUG, "TC inactive, relax p-state\n");
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p_param.y_k = 0.0;
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xk_1 = 0.0;
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xk_2 = 0.0;
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set_ctrl_state(0);
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}
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/* To be called at time interval Ts. Type C PID controller.
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* y[k] = y[k-1] - kp*(x[k] - x[k-1]) + Ki*Ts*e[k] - Kd*(x[k]
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* - 2*x[k-1]+x[k-2])/Ts
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* TODO: add low pass filter for D term
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*/
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#define GUARD_BAND (2)
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void controller_handler(const double xk, double *yk)
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{
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double ek;
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double p_term, i_term, d_term;
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ek = p_param.t_target - xk; /* error */
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if (ek >= 3.0) {
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syslog(LOG_DEBUG, "PID: %3.1f Below set point %3.1f, stop\n",
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xk, p_param.t_target);
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controller_reset();
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*yk = 0.0;
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return;
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}
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/* compute intermediate PID terms */
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p_term = -p_param.kp * (xk - xk_1);
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i_term = p_param.kp * p_param.ki * p_param.ts * ek;
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d_term = -p_param.kp * p_param.kd * (xk - 2 * xk_1 + xk_2) / p_param.ts;
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/* compute output */
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*yk += p_term + i_term + d_term;
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/* update sample data */
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xk_1 = xk;
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xk_2 = xk_1;
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/* clamp output adjustment range */
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if (*yk < -LIMIT_HIGH)
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*yk = -LIMIT_HIGH;
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else if (*yk > -LIMIT_LOW)
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*yk = -LIMIT_LOW;
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p_param.y_k = *yk;
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set_ctrl_state(lround(fabs(p_param.y_k)));
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}
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