| Benjamin Herrenschmidt | 75722d3 | 2005-11-07 16:08:17 +1100 | [diff] [blame] | 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 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); |