drivers/macintosh/windfarm_pid.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Windfarm PowerMac thermal control. Generic PID helpers
   4  *
   5  * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
   6  *                    <benh@kernel.crashing.org>
   7  *
   8  * This is a pair of generic PID helpers that can be used by
   9  * control loops. One is the basic PID implementation, the
  10  * other one is more specifically tailored to the loops used
  11  * for CPU control with 2 input sample types (temp and power)
  12  */
  13
  14 /*
  15  * *** Simple PID ***
  16  */
  17
  18 #define WF_PID_MAX_HISTORY      32
  19
  20 /* This parameter array is passed to the PID algorithm. Currently,
  21  * we don't support changing parameters on the fly as it's not needed
  22  * but could be implemented (with necessary adjustment of the history
  23  * buffer
  24  */
  25 struct wf_pid_param {
  26         int     interval;       /* Interval between samples in seconds */
  27         int     history_len;    /* Size of history buffer */
  28         int     additive;       /* 1: target relative to previous value */
  29         s32     gd, gp, gr;     /* PID gains */
  30         s32     itarget;        /* PID input target */
  31         s32     min,max;        /* min and max target values */
  32 };
  33
  34 struct wf_pid_state {
  35         int     first;                          /* first run of the loop */
  36         int     index;                          /* index of current sample */
  37         s32     target;                         /* current target value */
  38         s32     samples[WF_PID_MAX_HISTORY];    /* samples history buffer */
  39         s32     errors[WF_PID_MAX_HISTORY];     /* error history buffer */
  40
  41         struct wf_pid_param param;
  42 };
  43
  44 extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
  45 extern s32 wf_pid_run(struct wf_pid_state *st, s32 sample);
  46
  47
  48 /*
  49  * *** CPU PID ***
  50  */
  51
  52 #define WF_CPU_PID_MAX_HISTORY  32
  53
  54 /* This parameter array is passed to the CPU PID algorithm. Currently,
  55  * we don't support changing parameters on the fly as it's not needed
  56  * but could be implemented (with necessary adjustment of the history
  57  * buffer
  58  */
  59 struct wf_cpu_pid_param {
  60         int     interval;       /* Interval between samples in seconds */
  61         int     history_len;    /* Size of history buffer */
  62         s32     gd, gp, gr;     /* PID gains */
  63         s32     pmaxadj;        /* PID max power adjust */
  64         s32     ttarget;        /* PID input target */
  65         s32     tmax;           /* PID input max */
  66         s32     min,max;        /* min and max target values */
  67 };
  68
  69 struct wf_cpu_pid_state {
  70         int     first;                          /* first run of the loop */
  71         int     index;                          /* index of current power */
  72         int     tindex;                         /* index of current temp */
  73         s32     target;                         /* current target value */
  74         s32     last_delta;                     /* last Tactual - Ttarget */
  75         s32     powers[WF_PID_MAX_HISTORY];     /* power history buffer */
  76         s32     errors[WF_PID_MAX_HISTORY];     /* error history buffer */
  77         s32     temps[2];                       /* temp. history buffer */
  78
  79         struct wf_cpu_pid_param param;
  80 };
  81
  82 extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
  83                             struct wf_cpu_pid_param *param);
  84 extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);