linux/drivers/macintosh/windfarm_pid.h
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   1/*
   2 * Windfarm PowerMac thermal control. Generic PID helpers
   3 *
   4 * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
   5 *                    <benh@kernel.crashing.org>
   6 *
   7 * Released under the term of the GNU GPL v2.
   8 *
   9 * This is a pair of generic PID helpers that can be used by
  10 * control loops. One is the basic PID implementation, the
  11 * other one is more specifically tailored to the loops used
  12 * for CPU control with 2 input sample types (temp and power)
  13 */
  14
  15/*
  16 * *** Simple PID ***
  17 */
  18
  19#define WF_PID_MAX_HISTORY      32
  20
  21/* This parameter array is passed to the PID algorithm. Currently,
  22 * we don't support changing parameters on the fly as it's not needed
  23 * but could be implemented (with necessary adjustment of the history
  24 * buffer
  25 */
  26struct wf_pid_param {
  27        int     interval;       /* Interval between samples in seconds */
  28        int     history_len;    /* Size of history buffer */
  29        int     additive;       /* 1: target relative to previous value */
  30        s32     gd, gp, gr;     /* PID gains */
  31        s32     itarget;        /* PID input target */
  32        s32     min,max;        /* min and max target values */
  33};
  34
  35struct wf_pid_state {
  36        int     first;                          /* first run of the loop */
  37        int     index;                          /* index of current sample */
  38        s32     target;                         /* current target value */
  39        s32     samples[WF_PID_MAX_HISTORY];    /* samples history buffer */
  40        s32     errors[WF_PID_MAX_HISTORY];     /* error history buffer */
  41
  42        struct wf_pid_param param;
  43};
  44
  45extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
  46extern s32 wf_pid_run(struct wf_pid_state *st, s32 sample);
  47
  48
  49/*
  50 * *** CPU PID ***
  51 */
  52
  53#define WF_CPU_PID_MAX_HISTORY  32
  54
  55/* This parameter array is passed to the CPU PID algorithm. Currently,
  56 * we don't support changing parameters on the fly as it's not needed
  57 * but could be implemented (with necessary adjustment of the history
  58 * buffer
  59 */
  60struct wf_cpu_pid_param {
  61        int     interval;       /* Interval between samples in seconds */
  62        int     history_len;    /* Size of history buffer */
  63        s32     gd, gp, gr;     /* PID gains */
  64        s32     pmaxadj;        /* PID max power adjust */
  65        s32     ttarget;        /* PID input target */
  66        s32     tmax;           /* PID input max */
  67        s32     min,max;        /* min and max target values */
  68};
  69
  70struct wf_cpu_pid_state {
  71        int     first;                          /* first run of the loop */
  72        int     index;                          /* index of current power */
  73        int     tindex;                         /* index of current temp */
  74        s32     target;                         /* current target value */
  75        s32     last_delta;                     /* last Tactual - Ttarget */
  76        s32     powers[WF_PID_MAX_HISTORY];     /* power history buffer */
  77        s32     errors[WF_PID_MAX_HISTORY];     /* error history buffer */
  78        s32     temps[2];                       /* temp. history buffer */
  79
  80        struct wf_cpu_pid_param param;
  81};
  82
  83extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
  84                            struct wf_cpu_pid_param *param);
  85extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);
  86
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