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/arch/ppc/kernel/temp.c

https://bitbucket.org/evzijst/gittest
C | 272 lines | 165 code | 45 blank | 62 comment | 13 complexity | 87d770df0691814b8263c0a0f9f25468 MD5 | raw file
  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
 14#include <linux/config.h>
 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/segment.h>
 25#include <asm/io.h>
 26#include <asm/reg.h>
 27#include <asm/nvram.h>
 28#include <asm/cache.h>
 29#include <asm/8xx_immap.h>
 30#include <asm/machdep.h>
 31
 32static struct tau_temp
 33{
 34	int interrupts;
 35	unsigned char low;
 36	unsigned char high;
 37	unsigned char grew;
 38} tau[NR_CPUS];
 39
 40struct timer_list tau_timer;
 41
 42#undef DEBUG
 43
 44/* TODO: put these in a /proc interface, with some sanity checks, and maybe
 45 * dynamic adjustment to minimize # of interrupts */
 46/* configurable values for step size and how much to expand the window when
 47 * we get an interrupt. These are based on the limit that was out of range */
 48#define step_size		2	/* step size when temp goes out of range */
 49#define window_expand		1	/* expand the window by this much */
 50/* configurable values for shrinking the window */
 51#define shrink_timer	2*HZ	/* period between shrinking the window */
 52#define min_window	2	/* minimum window size, degrees C */
 53
 54void set_thresholds(unsigned long cpu)
 55{
 56#ifdef CONFIG_TAU_INT
 57	/*
 58	 * setup THRM1,
 59	 * threshold, valid bit, enable interrupts, interrupt when below threshold
 60	 */
 61	mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID);
 62
 63	/* setup THRM2,
 64	 * threshold, valid bit, enable interrupts, interrupt when above threshhold
 65	 */
 66	mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE);
 67#else
 68	/* same thing but don't enable interrupts */
 69	mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID);
 70	mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V);
 71#endif
 72}
 73
 74void TAUupdate(int cpu)
 75{
 76	unsigned thrm;
 77
 78#ifdef DEBUG
 79	printk("TAUupdate ");
 80#endif
 81
 82	/* if both thresholds are crossed, the step_sizes cancel out
 83	 * and the window winds up getting expanded twice. */
 84	if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */
 85		if(thrm & THRM1_TIN){ /* crossed low threshold */
 86			if (tau[cpu].low >= step_size){
 87				tau[cpu].low -= step_size;
 88				tau[cpu].high -= (step_size - window_expand);
 89			}
 90			tau[cpu].grew = 1;
 91#ifdef DEBUG
 92			printk("low threshold crossed ");
 93#endif
 94		}
 95	}
 96	if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */
 97		if(thrm & THRM1_TIN){ /* crossed high threshold */
 98			if (tau[cpu].high <= 127-step_size){
 99				tau[cpu].low += (step_size - window_expand);
100				tau[cpu].high += step_size;
101			}
102			tau[cpu].grew = 1;
103#ifdef DEBUG
104			printk("high threshold crossed ");
105#endif
106		}
107	}
108
109#ifdef DEBUG
110	printk("grew = %d\n", tau[cpu].grew);
111#endif
112
113#ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */
114	set_thresholds(cpu);
115#endif
116
117}
118
119#ifdef CONFIG_TAU_INT
120/*
121 * TAU interrupts - called when we have a thermal assist unit interrupt
122 * with interrupts disabled
123 */
124
125void TAUException(struct pt_regs * regs)
126{
127	int cpu = smp_processor_id();
128
129	irq_enter();
130	tau[cpu].interrupts++;
131
132	TAUupdate(cpu);
133
134	irq_exit();
135}
136#endif /* CONFIG_TAU_INT */
137
138static void tau_timeout(void * info)
139{
140	int cpu;
141	unsigned long flags;
142	int size;
143	int shrink;
144
145	/* disabling interrupts *should* be okay */
146	local_irq_save(flags);
147	cpu = smp_processor_id();
148
149#ifndef CONFIG_TAU_INT
150	TAUupdate(cpu);
151#endif
152
153	size = tau[cpu].high - tau[cpu].low;
154	if (size > min_window && ! tau[cpu].grew) {
155		/* do an exponential shrink of half the amount currently over size */
156		shrink = (2 + size - min_window) / 4;
157		if (shrink) {
158			tau[cpu].low += shrink;
159			tau[cpu].high -= shrink;
160		} else { /* size must have been min_window + 1 */
161			tau[cpu].low += 1;
162#if 1 /* debug */
163			if ((tau[cpu].high - tau[cpu].low) != min_window){
164				printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__);
165			}
166#endif
167		}
168	}
169
170	tau[cpu].grew = 0;
171
172	set_thresholds(cpu);
173
174	/*
175	 * Do the enable every time, since otherwise a bunch of (relatively)
176	 * complex sleep code needs to be added. One mtspr every time
177	 * tau_timeout is called is probably not a big deal.
178	 *
179	 * Enable thermal sensor and set up sample interval timer
180	 * need 20 us to do the compare.. until a nice 'cpu_speed' function
181	 * call is implemented, just assume a 500 mhz clock. It doesn't really
182	 * matter if we take too long for a compare since it's all interrupt
183	 * driven anyway.
184	 *
185	 * use a extra long time.. (60 us @ 500 mhz)
186	 */
187	mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E);
188
189	local_irq_restore(flags);
190}
191
192static void tau_timeout_smp(unsigned long unused)
193{
194
195	/* schedule ourselves to be run again */
196	mod_timer(&tau_timer, jiffies + shrink_timer) ;
197	on_each_cpu(tau_timeout, NULL, 1, 0);
198}
199
200/*
201 * setup the TAU
202 *
203 * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound.
204 * Start off at zero
205 */
206
207int tau_initialized = 0;
208
209void __init TAU_init_smp(void * info)
210{
211	unsigned long cpu = smp_processor_id();
212
213	/* set these to a reasonable value and let the timer shrink the
214	 * window */
215	tau[cpu].low = 5;
216	tau[cpu].high = 120;
217
218	set_thresholds(cpu);
219}
220
221int __init TAU_init(void)
222{
223	/* We assume in SMP that if one CPU has TAU support, they
224	 * all have it --BenH
225	 */
226	if (!cpu_has_feature(CPU_FTR_TAU)) {
227		printk("Thermal assist unit not available\n");
228		tau_initialized = 0;
229		return 1;
230	}
231
232
233	/* first, set up the window shrinking timer */
234	init_timer(&tau_timer);
235	tau_timer.function = tau_timeout_smp;
236	tau_timer.expires = jiffies + shrink_timer;
237	add_timer(&tau_timer);
238
239	on_each_cpu(TAU_init_smp, NULL, 1, 0);
240
241	printk("Thermal assist unit ");
242#ifdef CONFIG_TAU_INT
243	printk("using interrupts, ");
244#else
245	printk("using timers, ");
246#endif
247	printk("shrink_timer: %d jiffies\n", shrink_timer);
248	tau_initialized = 1;
249
250	return 0;
251}
252
253__initcall(TAU_init);
254
255/*
256 * return current temp
257 */
258
259u32 cpu_temp_both(unsigned long cpu)
260{
261	return ((tau[cpu].high << 16) | tau[cpu].low);
262}
263
264int cpu_temp(unsigned long cpu)
265{
266	return ((tau[cpu].high + tau[cpu].low) / 2);
267}
268
269int tau_interrupts(unsigned long cpu)
270{
271	return (tau[cpu].interrupts);
272}