1/* SPDX-License-Identifier: GPL-2.0-only */
2#ifndef _WINDFARM_PID_H
3#define _WINDFARM_PID_H
4
5/*
6 * Windfarm PowerMac thermal control. Generic PID helpers
7 *
8 * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
9 * <benh@kernel.crashing.org>
10 *
11 * This is a pair of generic PID helpers that can be used by
12 * control loops. One is the basic PID implementation, the
13 * other one is more specifically tailored to the loops used
14 * for CPU control with 2 input sample types (temp and power)
15 */
16
17/*
18 * *** Simple PID ***
19 */
20
21#define WF_PID_MAX_HISTORY 32
22
23/* This parameter array is passed to the PID algorithm. Currently,
24 * we don't support changing parameters on the fly as it's not needed
25 * but could be implemented (with necessary adjustment of the history
26 * buffer
27 */
28struct wf_pid_param {
29 int interval; /* Interval between samples in seconds */
30 int history_len; /* Size of history buffer */
31 int additive; /* 1: target relative to previous value */
32 s32 gd, gp, gr; /* PID gains */
33 s32 itarget; /* PID input target */
34 s32 min,max; /* min and max target values */
35};
36
37struct wf_pid_state {
38 int first; /* first run of the loop */
39 int index; /* index of current sample */
40 s32 target; /* current target value */
41 s32 samples[WF_PID_MAX_HISTORY]; /* samples history buffer */
42 s32 errors[WF_PID_MAX_HISTORY]; /* error history buffer */
43
44 struct wf_pid_param param;
45};
46
47extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
48extern s32 wf_pid_run(struct wf_pid_state *st, s32 sample);
49
50
51/*
52 * *** CPU PID ***
53 */
54
55#define WF_CPU_PID_MAX_HISTORY 32
56
57/* This parameter array is passed to the CPU PID algorithm. Currently,
58 * we don't support changing parameters on the fly as it's not needed
59 * but could be implemented (with necessary adjustment of the history
60 * buffer
61 */
62struct wf_cpu_pid_param {
63 int interval; /* Interval between samples in seconds */
64 int history_len; /* Size of history buffer */
65 s32 gd, gp, gr; /* PID gains */
66 s32 pmaxadj; /* PID max power adjust */
67 s32 ttarget; /* PID input target */
68 s32 tmax; /* PID input max */
69 s32 min,max; /* min and max target values */
70};
71
72struct wf_cpu_pid_state {
73 int first; /* first run of the loop */
74 int index; /* index of current power */
75 int tindex; /* index of current temp */
76 s32 target; /* current target value */
77 s32 last_delta; /* last Tactual - Ttarget */
78 s32 powers[WF_PID_MAX_HISTORY]; /* power history buffer */
79 s32 errors[WF_PID_MAX_HISTORY]; /* error history buffer */
80 s32 temps[2]; /* temp. history buffer */
81
82 struct wf_cpu_pid_param param;
83};
84
85extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
86 struct wf_cpu_pid_param *param);
87extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);
88
89#endif /* _WINDFARM_PID_H */
90

source code of linux/drivers/macintosh/windfarm_pid.h