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