projects / linux-2.6 / blame
| Commit | Line | Data |
|---|---|---|
| 75722d39 BH |
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 | ||
| 10 | #include <linux/types.h> | |
| 11 | #include <linux/errno.h> | |
| 12 | #include <linux/kernel.h> | |
| 13 | #include <linux/string.h> | |
| 14 | #include <linux/module.h> | |
| 15 | ||
| 16 | #include "windfarm_pid.h" | |
| 17 | ||
| 18 | #undef DEBUG | |
| 19 | ||
| 20 | #ifdef DEBUG | |
| 21 | #define DBG(args...) printk(args) | |
| 22 | #else | |
| 23 | #define DBG(args...) do { } while(0) | |
| 24 | #endif | |
| 25 | ||
| 26 | void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param) | |
| 27 | { | |
| 28 | memset(st, 0, sizeof(struct wf_pid_state)); | |
| 29 | st->param = *param; | |
| 30 | st->first = 1; | |
| 31 | } | |
| 32 | EXPORT_SYMBOL_GPL(wf_pid_init); | |
| 33 | ||
| 34 | s32 wf_pid_run(struct wf_pid_state *st, s32 new_sample) | |
| 35 | { | |
| 36 | s64 error, integ, deriv; | |
| 37 | s32 target; | |
| 38 | int i, hlen = st->param.history_len; | |
| 39 | ||
| 40 | /* Calculate error term */ | |
| 41 | error = new_sample - st->param.itarget; | |
| 42 | ||
| 43 | /* Get samples into our history buffer */ | |
| 44 | if (st->first) { | |
| 45 | for (i = 0; i < hlen; i++) { | |
| 46 | st->samples[i] = new_sample; | |
| 47 | st->errors[i] = error; | |
| 48 | } | |
| 49 | st->first = 0; | |
| 50 | st->index = 0; | |
| 51 | } else { | |
| 52 | st->index = (st->index + 1) % hlen; | |
| 53 | st->samples[st->index] = new_sample; | |
| 54 | st->errors[st->index] = error; | |
| 55 | } | |
| 56 | ||
| 57 | /* Calculate integral term */ | |
| 58 | for (i = 0, integ = 0; i < hlen; i++) | |
| 59 | integ += st->errors[(st->index + hlen - i) % hlen]; | |
| 60 | integ *= st->param.interval; | |
| 61 | ||
| 62 | /* Calculate derivative term */ | |
| 63 | deriv = st->errors[st->index] - | |
| 64 | st->errors[(st->index + hlen - 1) % hlen]; | |
| 65 | deriv /= st->param.interval; | |
| 66 | ||
| 67 | /* Calculate target */ | |
| 68 | target = (s32)((integ * (s64)st->param.gr + deriv * (s64)st->param.gd + | |
| 69 | error * (s64)st->param.gp) >> 36); | |
| 70 | if (st->param.additive) | |
| 71 | target += st->target; | |
| 72 | target = max(target, st->param.min); | |
| 73 | target = min(target, st->param.max); | |
| 74 | st->target = target; | |
| 75 | ||
| 76 | return st->target; | |
| 77 | } | |
| 78 | EXPORT_SYMBOL_GPL(wf_pid_run); | |
| 79 | ||
| 80 | void wf_cpu_pid_init(struct wf_cpu_pid_state *st, | |
| 81 | struct wf_cpu_pid_param *param) | |
| 82 | { | |
| 83 | memset(st, 0, sizeof(struct wf_cpu_pid_state)); | |
| 84 | st->param = *param; | |
| 85 | st->first = 1; | |
| 86 | } | |
| 87 | EXPORT_SYMBOL_GPL(wf_cpu_pid_init); | |
| 88 | ||
| 89 | s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 new_power, s32 new_temp) | |
| 90 | { | |
| ac171c46 BH |
91 | s64 integ, deriv, prop; |
| 92 | s32 error, target, sval, adj; | |
| 75722d39 BH |
93 | int i, hlen = st->param.history_len; |
| 94 | ||
| 95 | /* Calculate error term */ | |
| 96 | error = st->param.pmaxadj - new_power; | |
| 97 | ||
| 98 | /* Get samples into our history buffer */ | |
| 99 | if (st->first) { | |
| 100 | for (i = 0; i < hlen; i++) { | |
| 101 | st->powers[i] = new_power; | |
| 102 | st->errors[i] = error; | |
| 103 | } | |
| 104 | st->temps[0] = st->temps[1] = new_temp; | |
| 105 | st->first = 0; | |
| 106 | st->index = st->tindex = 0; | |
| 107 | } else { | |
| 108 | st->index = (st->index + 1) % hlen; | |
| 109 | st->powers[st->index] = new_power; | |
| 110 | st->errors[st->index] = error; | |
| 111 | st->tindex = (st->tindex + 1) % 2; | |
| 112 | st->temps[st->tindex] = new_temp; | |
| 113 | } | |
| 114 | ||
| 115 | /* Calculate integral term */ | |
| 116 | for (i = 0, integ = 0; i < hlen; i++) | |
| 117 | integ += st->errors[(st->index + hlen - i) % hlen]; | |
| 118 | integ *= st->param.interval; | |
| 119 | integ *= st->param.gr; | |
| ac171c46 | 120 | sval = st->param.tmax - (s32)(integ >> 20); |
| 75722d39 BH |
121 | adj = min(st->param.ttarget, sval); |
| 122 | ||
| 123 | DBG("integ: %lx, sval: %lx, adj: %lx\n", integ, sval, adj); | |
| 124 | ||
| 125 | /* Calculate derivative term */ | |
| 126 | deriv = st->temps[st->tindex] - | |
| 127 | st->temps[(st->tindex + 2 - 1) % 2]; | |
| 128 | deriv /= st->param.interval; | |
| 129 | deriv *= st->param.gd; | |
| 130 | ||
| 131 | /* Calculate proportional term */ | |
| ac171c46 | 132 | prop = st->last_delta = (new_temp - adj); |
| 75722d39 BH |
133 | prop *= st->param.gp; |
| 134 | ||
| 135 | DBG("deriv: %lx, prop: %lx\n", deriv, prop); | |
| 136 | ||
| 137 | /* Calculate target */ | |
| 138 | target = st->target + (s32)((deriv + prop) >> 36); | |
| 139 | target = max(target, st->param.min); | |
| 140 | target = min(target, st->param.max); | |
| 141 | st->target = target; | |
| 142 | ||
| 143 | return st->target; | |
| 144 | } | |
| 145 | EXPORT_SYMBOL_GPL(wf_cpu_pid_run); | |
| cdd440fe BH |
146 | |
| 147 | MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>"); | |
| 148 | MODULE_DESCRIPTION("PID algorithm for PowerMacs thermal control"); | |
| 149 | MODULE_LICENSE("GPL"); |