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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 | |
| 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 | { |
| 91 | s64 integ, deriv, prop; |
| 92 | s32 error, target, sval, adj; |
| 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; |
| 120 | sval = st->param.tmax - (s32)(integ >> 20); |
| 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 */ |
| 132 | prop = st->last_delta = (new_temp - adj); |
| 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); |
| 146 | |
| 147 | MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>"); |
| 148 | MODULE_DESCRIPTION("PID algorithm for PowerMacs thermal control"); |
| 149 | MODULE_LICENSE("GPL"); |
| 150 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
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v3.9
