drivers/macintosh/windfarm_pid.h

   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  */
  26 struct 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
  35 struct 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
  45 extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
  46 extern 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  */
  60 struct 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
  70 struct 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
  83 extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
  84                             struct wf_cpu_pid_param *param);
  85 extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);