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2c162f9b | 1 | // SPDX-License-Identifier: GPL-2.0-only |
75722d39 BH |
2 | /* |
3 | * Windfarm PowerMac thermal control. Generic PID helpers | |
4 | * | |
5 | * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp. | |
6 | * <benh@kernel.crashing.org> | |
75722d39 BH |
7 | */ |
8 | ||
9 | #include <linux/types.h> | |
10 | #include <linux/errno.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/string.h> | |
13 | #include <linux/module.h> | |
14 | ||
15 | #include "windfarm_pid.h" | |
16 | ||
17 | #undef DEBUG | |
18 | ||
19 | #ifdef DEBUG | |
20 | #define DBG(args...) printk(args) | |
21 | #else | |
22 | #define DBG(args...) do { } while(0) | |
23 | #endif | |
24 | ||
25 | void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param) | |
26 | { | |
27 | memset(st, 0, sizeof(struct wf_pid_state)); | |
28 | st->param = *param; | |
29 | st->first = 1; | |
30 | } | |
31 | EXPORT_SYMBOL_GPL(wf_pid_init); | |
32 | ||
33 | s32 wf_pid_run(struct wf_pid_state *st, s32 new_sample) | |
34 | { | |
35 | s64 error, integ, deriv; | |
36 | s32 target; | |
37 | int i, hlen = st->param.history_len; | |
38 | ||
39 | /* Calculate error term */ | |
40 | error = new_sample - st->param.itarget; | |
41 | ||
42 | /* Get samples into our history buffer */ | |
43 | if (st->first) { | |
44 | for (i = 0; i < hlen; i++) { | |
45 | st->samples[i] = new_sample; | |
46 | st->errors[i] = error; | |
47 | } | |
48 | st->first = 0; | |
49 | st->index = 0; | |
50 | } else { | |
51 | st->index = (st->index + 1) % hlen; | |
52 | st->samples[st->index] = new_sample; | |
53 | st->errors[st->index] = error; | |
54 | } | |
55 | ||
56 | /* Calculate integral term */ | |
57 | for (i = 0, integ = 0; i < hlen; i++) | |
58 | integ += st->errors[(st->index + hlen - i) % hlen]; | |
59 | integ *= st->param.interval; | |
60 | ||
61 | /* Calculate derivative term */ | |
62 | deriv = st->errors[st->index] - | |
63 | st->errors[(st->index + hlen - 1) % hlen]; | |
64 | deriv /= st->param.interval; | |
65 | ||
66 | /* Calculate target */ | |
67 | target = (s32)((integ * (s64)st->param.gr + deriv * (s64)st->param.gd + | |
68 | error * (s64)st->param.gp) >> 36); | |
69 | if (st->param.additive) | |
70 | target += st->target; | |
71 | target = max(target, st->param.min); | |
72 | target = min(target, st->param.max); | |
73 | st->target = target; | |
74 | ||
75 | return st->target; | |
76 | } | |
77 | EXPORT_SYMBOL_GPL(wf_pid_run); | |
78 | ||
79 | void wf_cpu_pid_init(struct wf_cpu_pid_state *st, | |
80 | struct wf_cpu_pid_param *param) | |
81 | { | |
82 | memset(st, 0, sizeof(struct wf_cpu_pid_state)); | |
83 | st->param = *param; | |
84 | st->first = 1; | |
85 | } | |
86 | EXPORT_SYMBOL_GPL(wf_cpu_pid_init); | |
87 | ||
88 | s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 new_power, s32 new_temp) | |
89 | { | |
ac171c46 BH |
90 | s64 integ, deriv, prop; |
91 | s32 error, target, sval, adj; | |
75722d39 BH |
92 | int i, hlen = st->param.history_len; |
93 | ||
94 | /* Calculate error term */ | |
95 | error = st->param.pmaxadj - new_power; | |
96 | ||
97 | /* Get samples into our history buffer */ | |
98 | if (st->first) { | |
99 | for (i = 0; i < hlen; i++) { | |
100 | st->powers[i] = new_power; | |
101 | st->errors[i] = error; | |
102 | } | |
103 | st->temps[0] = st->temps[1] = new_temp; | |
104 | st->first = 0; | |
105 | st->index = st->tindex = 0; | |
106 | } else { | |
107 | st->index = (st->index + 1) % hlen; | |
108 | st->powers[st->index] = new_power; | |
109 | st->errors[st->index] = error; | |
110 | st->tindex = (st->tindex + 1) % 2; | |
111 | st->temps[st->tindex] = new_temp; | |
112 | } | |
113 | ||
114 | /* Calculate integral term */ | |
115 | for (i = 0, integ = 0; i < hlen; i++) | |
116 | integ += st->errors[(st->index + hlen - i) % hlen]; | |
117 | integ *= st->param.interval; | |
118 | integ *= st->param.gr; | |
ac171c46 | 119 | sval = st->param.tmax - (s32)(integ >> 20); |
75722d39 BH |
120 | adj = min(st->param.ttarget, sval); |
121 | ||
122 | DBG("integ: %lx, sval: %lx, adj: %lx\n", integ, sval, adj); | |
123 | ||
124 | /* Calculate derivative term */ | |
125 | deriv = st->temps[st->tindex] - | |
126 | st->temps[(st->tindex + 2 - 1) % 2]; | |
127 | deriv /= st->param.interval; | |
128 | deriv *= st->param.gd; | |
129 | ||
130 | /* Calculate proportional term */ | |
ac171c46 | 131 | prop = st->last_delta = (new_temp - adj); |
75722d39 BH |
132 | prop *= st->param.gp; |
133 | ||
134 | DBG("deriv: %lx, prop: %lx\n", deriv, prop); | |
135 | ||
136 | /* Calculate target */ | |
137 | target = st->target + (s32)((deriv + prop) >> 36); | |
138 | target = max(target, st->param.min); | |
139 | target = min(target, st->param.max); | |
140 | st->target = target; | |
141 | ||
142 | return st->target; | |
143 | } | |
144 | EXPORT_SYMBOL_GPL(wf_cpu_pid_run); | |
cdd440fe BH |
145 | |
146 | MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>"); | |
147 | MODULE_DESCRIPTION("PID algorithm for PowerMacs thermal control"); | |
148 | MODULE_LICENSE("GPL"); |