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 | |
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 | { |
90 | s64 integ, deriv, prop; |
91 | s32 error, target, sval, adj; |
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; |
119 | sval = st->param.tmax - (s32)(integ >> 20); |
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 */ |
131 | prop = st->last_delta = (new_temp - adj); |
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); |
145 | |
146 | MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>" ); |
147 | MODULE_DESCRIPTION("PID algorithm for PowerMacs thermal control" ); |
148 | MODULE_LICENSE("GPL" ); |
149 | |