LXR linux/drivers/macintosh/windfarm

   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 */
  25struct 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
  34struct 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
  44extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
  45extern 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 */
  59struct 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
  69struct 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
  82extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
  83                            struct wf_cpu_pid_param *param);
  84extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);
  85