1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * temp.c Thermal management for cpu's with Thermal Assist Units
4 *
5 * Written by Troy Benjegerdes <hozer@drgw.net>
6 *
7 * TODO:
8 * dynamic power management to limit peak CPU temp (using ICTC)
9 * calibration???
10 *
11 * Silly, crazy ideas: use cpu load (from scheduler) and ICTC to extend battery
12 * life in portables, and add a 'performance/watt' metric somewhere in /proc
13 */
14
15 #include <linux/errno.h>
16 #include <linux/jiffies.h>
17 #include <linux/kernel.h>
18 #include <linux/param.h>
19 #include <linux/string.h>
20 #include <linux/mm.h>
21 #include <linux/interrupt.h>
22 #include <linux/init.h>
23
24 #include <asm/io.h>
25 #include <asm/reg.h>
26 #include <asm/nvram.h>
27 #include <asm/cache.h>
28 #include <asm/8xx_immap.h>
29 #include <asm/machdep.h>
30 #include <asm/asm-prototypes.h>
31
32 #include "setup.h"
33
34 static struct tau_temp
35 {
36 int interrupts;
37 unsigned char low;
38 unsigned char high;
39 unsigned char grew;
40 } tau[NR_CPUS];
41
42 struct timer_list tau_timer;
43
44 #undef DEBUG
45
46 /* TODO: put these in a /proc interface, with some sanity checks, and maybe
47 * dynamic adjustment to minimize # of interrupts */
48 /* configurable values for step size and how much to expand the window when
49 * we get an interrupt. These are based on the limit that was out of range */
50 #define step_size 2 /* step size when temp goes out of range */
51 #define window_expand 1 /* expand the window by this much */
52 /* configurable values for shrinking the window */
53 #define shrink_timer 2*HZ /* period between shrinking the window */
54 #define min_window 2 /* minimum window size, degrees C */
55
set_thresholds(unsigned long cpu)56 static void set_thresholds(unsigned long cpu)
57 {
58 #ifdef CONFIG_TAU_INT
59 /*
60 * setup THRM1,
61 * threshold, valid bit, enable interrupts, interrupt when below threshold
62 */
63 mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID);
64
65 /* setup THRM2,
66 * threshold, valid bit, enable interrupts, interrupt when above threshold
67 */
68 mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE);
69 #else
70 /* same thing but don't enable interrupts */
71 mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID);
72 mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V);
73 #endif
74 }
75
TAUupdate(int cpu)76 static void TAUupdate(int cpu)
77 {
78 unsigned thrm;
79
80 #ifdef DEBUG
81 printk("TAUupdate ");
82 #endif
83
84 /* if both thresholds are crossed, the step_sizes cancel out
85 * and the window winds up getting expanded twice. */
86 if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */
87 if(thrm & THRM1_TIN){ /* crossed low threshold */
88 if (tau[cpu].low >= step_size){
89 tau[cpu].low -= step_size;
90 tau[cpu].high -= (step_size - window_expand);
91 }
92 tau[cpu].grew = 1;
93 #ifdef DEBUG
94 printk("low threshold crossed ");
95 #endif
96 }
97 }
98 if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */
99 if(thrm & THRM1_TIN){ /* crossed high threshold */
100 if (tau[cpu].high <= 127-step_size){
101 tau[cpu].low += (step_size - window_expand);
102 tau[cpu].high += step_size;
103 }
104 tau[cpu].grew = 1;
105 #ifdef DEBUG
106 printk("high threshold crossed ");
107 #endif
108 }
109 }
110
111 #ifdef DEBUG
112 printk("grew = %d\n", tau[cpu].grew);
113 #endif
114
115 #ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */
116 set_thresholds(cpu);
117 #endif
118
119 }
120
121 #ifdef CONFIG_TAU_INT
122 /*
123 * TAU interrupts - called when we have a thermal assist unit interrupt
124 * with interrupts disabled
125 */
126
TAUException(struct pt_regs * regs)127 void TAUException(struct pt_regs * regs)
128 {
129 int cpu = smp_processor_id();
130
131 irq_enter();
132 tau[cpu].interrupts++;
133
134 TAUupdate(cpu);
135
136 irq_exit();
137 }
138 #endif /* CONFIG_TAU_INT */
139
tau_timeout(void * info)140 static void tau_timeout(void * info)
141 {
142 int cpu;
143 unsigned long flags;
144 int size;
145 int shrink;
146
147 /* disabling interrupts *should* be okay */
148 local_irq_save(flags);
149 cpu = smp_processor_id();
150
151 #ifndef CONFIG_TAU_INT
152 TAUupdate(cpu);
153 #endif
154
155 size = tau[cpu].high - tau[cpu].low;
156 if (size > min_window && ! tau[cpu].grew) {
157 /* do an exponential shrink of half the amount currently over size */
158 shrink = (2 + size - min_window) / 4;
159 if (shrink) {
160 tau[cpu].low += shrink;
161 tau[cpu].high -= shrink;
162 } else { /* size must have been min_window + 1 */
163 tau[cpu].low += 1;
164 #if 1 /* debug */
165 if ((tau[cpu].high - tau[cpu].low) != min_window){
166 printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__);
167 }
168 #endif
169 }
170 }
171
172 tau[cpu].grew = 0;
173
174 set_thresholds(cpu);
175
176 /*
177 * Do the enable every time, since otherwise a bunch of (relatively)
178 * complex sleep code needs to be added. One mtspr every time
179 * tau_timeout is called is probably not a big deal.
180 *
181 * Enable thermal sensor and set up sample interval timer
182 * need 20 us to do the compare.. until a nice 'cpu_speed' function
183 * call is implemented, just assume a 500 mhz clock. It doesn't really
184 * matter if we take too long for a compare since it's all interrupt
185 * driven anyway.
186 *
187 * use a extra long time.. (60 us @ 500 mhz)
188 */
189 mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E);
190
191 local_irq_restore(flags);
192 }
193
tau_timeout_smp(struct timer_list * unused)194 static void tau_timeout_smp(struct timer_list *unused)
195 {
196
197 /* schedule ourselves to be run again */
198 mod_timer(&tau_timer, jiffies + shrink_timer) ;
199 on_each_cpu(tau_timeout, NULL, 0);
200 }
201
202 /*
203 * setup the TAU
204 *
205 * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound.
206 * Start off at zero
207 */
208
209 int tau_initialized = 0;
210
TAU_init_smp(void * info)211 static void __init TAU_init_smp(void *info)
212 {
213 unsigned long cpu = smp_processor_id();
214
215 /* set these to a reasonable value and let the timer shrink the
216 * window */
217 tau[cpu].low = 5;
218 tau[cpu].high = 120;
219
220 set_thresholds(cpu);
221 }
222
TAU_init(void)223 static int __init TAU_init(void)
224 {
225 /* We assume in SMP that if one CPU has TAU support, they
226 * all have it --BenH
227 */
228 if (!cpu_has_feature(CPU_FTR_TAU)) {
229 printk("Thermal assist unit not available\n");
230 tau_initialized = 0;
231 return 1;
232 }
233
234
235 /* first, set up the window shrinking timer */
236 timer_setup(&tau_timer, tau_timeout_smp, 0);
237 tau_timer.expires = jiffies + shrink_timer;
238 add_timer(&tau_timer);
239
240 on_each_cpu(TAU_init_smp, NULL, 0);
241
242 printk("Thermal assist unit ");
243 #ifdef CONFIG_TAU_INT
244 printk("using interrupts, ");
245 #else
246 printk("using timers, ");
247 #endif
248 printk("shrink_timer: %d jiffies\n", shrink_timer);
249 tau_initialized = 1;
250
251 return 0;
252 }
253
254 __initcall(TAU_init);
255
256 /*
257 * return current temp
258 */
259
cpu_temp_both(unsigned long cpu)260 u32 cpu_temp_both(unsigned long cpu)
261 {
262 return ((tau[cpu].high << 16) | tau[cpu].low);
263 }
264
cpu_temp(unsigned long cpu)265 u32 cpu_temp(unsigned long cpu)
266 {
267 return ((tau[cpu].high + tau[cpu].low) / 2);
268 }
269
tau_interrupts(unsigned long cpu)270 u32 tau_interrupts(unsigned long cpu)
271 {
272 return (tau[cpu].interrupts);
273 }
274
