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1da177e4 LT |
1 | /* |
2 | * temp.c Thermal management for cpu's with Thermal Assist Units | |
3 | * | |
4 | * Written by Troy Benjegerdes <hozer@drgw.net> | |
5 | * | |
6 | * TODO: | |
7 | * dynamic power management to limit peak CPU temp (using ICTC) | |
8 | * calibration??? | |
9 | * | |
10 | * Silly, crazy ideas: use cpu load (from scheduler) and ICTC to extend battery | |
11 | * life in portables, and add a 'performance/watt' metric somewhere in /proc | |
12 | */ | |
13 | ||
1da177e4 LT |
14 | #include <linux/errno.h> |
15 | #include <linux/jiffies.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/param.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/interrupt.h> | |
21 | #include <linux/init.h> | |
22 | ||
1da177e4 LT |
23 | #include <asm/io.h> |
24 | #include <asm/reg.h> | |
25 | #include <asm/nvram.h> | |
26 | #include <asm/cache.h> | |
27 | #include <asm/8xx_immap.h> | |
28 | #include <asm/machdep.h> | |
29 | ||
30 | static struct tau_temp | |
31 | { | |
32 | int interrupts; | |
33 | unsigned char low; | |
34 | unsigned char high; | |
35 | unsigned char grew; | |
36 | } tau[NR_CPUS]; | |
37 | ||
38 | struct timer_list tau_timer; | |
39 | ||
40 | #undef DEBUG | |
41 | ||
42 | /* TODO: put these in a /proc interface, with some sanity checks, and maybe | |
43 | * dynamic adjustment to minimize # of interrupts */ | |
44 | /* configurable values for step size and how much to expand the window when | |
45 | * we get an interrupt. These are based on the limit that was out of range */ | |
46 | #define step_size 2 /* step size when temp goes out of range */ | |
47 | #define window_expand 1 /* expand the window by this much */ | |
48 | /* configurable values for shrinking the window */ | |
49 | #define shrink_timer 2*HZ /* period between shrinking the window */ | |
50 | #define min_window 2 /* minimum window size, degrees C */ | |
51 | ||
52 | void set_thresholds(unsigned long cpu) | |
53 | { | |
54 | #ifdef CONFIG_TAU_INT | |
55 | /* | |
56 | * setup THRM1, | |
57 | * threshold, valid bit, enable interrupts, interrupt when below threshold | |
58 | */ | |
59 | mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID); | |
60 | ||
61 | /* setup THRM2, | |
62 | * threshold, valid bit, enable interrupts, interrupt when above threshhold | |
63 | */ | |
64 | mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE); | |
65 | #else | |
66 | /* same thing but don't enable interrupts */ | |
67 | mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID); | |
68 | mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V); | |
69 | #endif | |
70 | } | |
71 | ||
72 | void TAUupdate(int cpu) | |
73 | { | |
74 | unsigned thrm; | |
75 | ||
76 | #ifdef DEBUG | |
77 | printk("TAUupdate "); | |
78 | #endif | |
79 | ||
80 | /* if both thresholds are crossed, the step_sizes cancel out | |
81 | * and the window winds up getting expanded twice. */ | |
82 | if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */ | |
83 | if(thrm & THRM1_TIN){ /* crossed low threshold */ | |
84 | if (tau[cpu].low >= step_size){ | |
85 | tau[cpu].low -= step_size; | |
86 | tau[cpu].high -= (step_size - window_expand); | |
87 | } | |
88 | tau[cpu].grew = 1; | |
89 | #ifdef DEBUG | |
90 | printk("low threshold crossed "); | |
91 | #endif | |
92 | } | |
93 | } | |
94 | if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */ | |
95 | if(thrm & THRM1_TIN){ /* crossed high threshold */ | |
96 | if (tau[cpu].high <= 127-step_size){ | |
97 | tau[cpu].low += (step_size - window_expand); | |
98 | tau[cpu].high += step_size; | |
99 | } | |
100 | tau[cpu].grew = 1; | |
101 | #ifdef DEBUG | |
102 | printk("high threshold crossed "); | |
103 | #endif | |
104 | } | |
105 | } | |
106 | ||
107 | #ifdef DEBUG | |
108 | printk("grew = %d\n", tau[cpu].grew); | |
109 | #endif | |
110 | ||
111 | #ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */ | |
112 | set_thresholds(cpu); | |
113 | #endif | |
114 | ||
115 | } | |
116 | ||
117 | #ifdef CONFIG_TAU_INT | |
118 | /* | |
119 | * TAU interrupts - called when we have a thermal assist unit interrupt | |
120 | * with interrupts disabled | |
121 | */ | |
122 | ||
123 | void TAUException(struct pt_regs * regs) | |
124 | { | |
125 | int cpu = smp_processor_id(); | |
126 | ||
127 | irq_enter(); | |
128 | tau[cpu].interrupts++; | |
129 | ||
130 | TAUupdate(cpu); | |
131 | ||
132 | irq_exit(); | |
133 | } | |
134 | #endif /* CONFIG_TAU_INT */ | |
135 | ||
136 | static void tau_timeout(void * info) | |
137 | { | |
138 | int cpu; | |
139 | unsigned long flags; | |
140 | int size; | |
141 | int shrink; | |
142 | ||
143 | /* disabling interrupts *should* be okay */ | |
144 | local_irq_save(flags); | |
145 | cpu = smp_processor_id(); | |
146 | ||
147 | #ifndef CONFIG_TAU_INT | |
148 | TAUupdate(cpu); | |
149 | #endif | |
150 | ||
151 | size = tau[cpu].high - tau[cpu].low; | |
152 | if (size > min_window && ! tau[cpu].grew) { | |
153 | /* do an exponential shrink of half the amount currently over size */ | |
154 | shrink = (2 + size - min_window) / 4; | |
155 | if (shrink) { | |
156 | tau[cpu].low += shrink; | |
157 | tau[cpu].high -= shrink; | |
158 | } else { /* size must have been min_window + 1 */ | |
159 | tau[cpu].low += 1; | |
160 | #if 1 /* debug */ | |
161 | if ((tau[cpu].high - tau[cpu].low) != min_window){ | |
162 | printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__); | |
163 | } | |
164 | #endif | |
165 | } | |
166 | } | |
167 | ||
168 | tau[cpu].grew = 0; | |
169 | ||
170 | set_thresholds(cpu); | |
171 | ||
172 | /* | |
173 | * Do the enable every time, since otherwise a bunch of (relatively) | |
174 | * complex sleep code needs to be added. One mtspr every time | |
175 | * tau_timeout is called is probably not a big deal. | |
176 | * | |
177 | * Enable thermal sensor and set up sample interval timer | |
178 | * need 20 us to do the compare.. until a nice 'cpu_speed' function | |
179 | * call is implemented, just assume a 500 mhz clock. It doesn't really | |
180 | * matter if we take too long for a compare since it's all interrupt | |
181 | * driven anyway. | |
182 | * | |
183 | * use a extra long time.. (60 us @ 500 mhz) | |
184 | */ | |
185 | mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E); | |
186 | ||
187 | local_irq_restore(flags); | |
188 | } | |
189 | ||
190 | static void tau_timeout_smp(unsigned long unused) | |
191 | { | |
192 | ||
193 | /* schedule ourselves to be run again */ | |
194 | mod_timer(&tau_timer, jiffies + shrink_timer) ; | |
15c8b6c1 | 195 | on_each_cpu(tau_timeout, NULL, 0); |
1da177e4 LT |
196 | } |
197 | ||
198 | /* | |
199 | * setup the TAU | |
200 | * | |
201 | * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound. | |
202 | * Start off at zero | |
203 | */ | |
204 | ||
205 | int tau_initialized = 0; | |
206 | ||
207 | void __init TAU_init_smp(void * info) | |
208 | { | |
209 | unsigned long cpu = smp_processor_id(); | |
210 | ||
211 | /* set these to a reasonable value and let the timer shrink the | |
212 | * window */ | |
213 | tau[cpu].low = 5; | |
214 | tau[cpu].high = 120; | |
215 | ||
216 | set_thresholds(cpu); | |
217 | } | |
218 | ||
219 | int __init TAU_init(void) | |
220 | { | |
221 | /* We assume in SMP that if one CPU has TAU support, they | |
222 | * all have it --BenH | |
223 | */ | |
224 | if (!cpu_has_feature(CPU_FTR_TAU)) { | |
225 | printk("Thermal assist unit not available\n"); | |
226 | tau_initialized = 0; | |
227 | return 1; | |
228 | } | |
229 | ||
230 | ||
231 | /* first, set up the window shrinking timer */ | |
232 | init_timer(&tau_timer); | |
233 | tau_timer.function = tau_timeout_smp; | |
234 | tau_timer.expires = jiffies + shrink_timer; | |
235 | add_timer(&tau_timer); | |
236 | ||
15c8b6c1 | 237 | on_each_cpu(TAU_init_smp, NULL, 0); |
1da177e4 LT |
238 | |
239 | printk("Thermal assist unit "); | |
240 | #ifdef CONFIG_TAU_INT | |
241 | printk("using interrupts, "); | |
242 | #else | |
243 | printk("using timers, "); | |
244 | #endif | |
245 | printk("shrink_timer: %d jiffies\n", shrink_timer); | |
246 | tau_initialized = 1; | |
247 | ||
248 | return 0; | |
249 | } | |
250 | ||
251 | __initcall(TAU_init); | |
252 | ||
253 | /* | |
254 | * return current temp | |
255 | */ | |
256 | ||
257 | u32 cpu_temp_both(unsigned long cpu) | |
258 | { | |
259 | return ((tau[cpu].high << 16) | tau[cpu].low); | |
260 | } | |
261 | ||
262 | int cpu_temp(unsigned long cpu) | |
263 | { | |
264 | return ((tau[cpu].high + tau[cpu].low) / 2); | |
265 | } | |
266 | ||
267 | int tau_interrupts(unsigned long cpu) | |
268 | { | |
269 | return (tau[cpu].interrupts); | |
270 | } |