2 * Windfarm PowerMac thermal control. Generic PID helpers
4 * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
5 * <benh@kernel.crashing.org>
7 * Released under the term of the GNU GPL v2.
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)
19 #define WF_PID_MAX_HISTORY 32
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
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 */
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 */
42 struct wf_pid_param param
;
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
);
53 #define WF_CPU_PID_MAX_HISTORY 32
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
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 */
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 */
80 struct wf_cpu_pid_param param
;
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
);
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