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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 | */ | |
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); |