271 lines
6.2 KiB
C
271 lines
6.2 KiB
C
/*
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* temp.c Thermal management for cpu's with Thermal Assist Units
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*
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* Written by Troy Benjegerdes <hozer@drgw.net>
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*
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* TODO:
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* dynamic power management to limit peak CPU temp (using ICTC)
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* calibration???
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*
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* Silly, crazy ideas: use cpu load (from scheduler) and ICTC to extend battery
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* life in portables, and add a 'performance/watt' metric somewhere in /proc
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*/
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#include <linux/errno.h>
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#include <linux/jiffies.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <asm/io.h>
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#include <asm/reg.h>
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#include <asm/nvram.h>
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#include <asm/cache.h>
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#include <asm/8xx_immap.h>
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#include <asm/machdep.h>
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static struct tau_temp
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{
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int interrupts;
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unsigned char low;
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unsigned char high;
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unsigned char grew;
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} tau[NR_CPUS];
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struct timer_list tau_timer;
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#undef DEBUG
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/* TODO: put these in a /proc interface, with some sanity checks, and maybe
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* dynamic adjustment to minimize # of interrupts */
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/* configurable values for step size and how much to expand the window when
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* we get an interrupt. These are based on the limit that was out of range */
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#define step_size 2 /* step size when temp goes out of range */
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#define window_expand 1 /* expand the window by this much */
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/* configurable values for shrinking the window */
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#define shrink_timer 2*HZ /* period between shrinking the window */
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#define min_window 2 /* minimum window size, degrees C */
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void set_thresholds(unsigned long cpu)
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{
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#ifdef CONFIG_TAU_INT
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/*
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* setup THRM1,
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* threshold, valid bit, enable interrupts, interrupt when below threshold
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*/
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mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID);
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/* setup THRM2,
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* threshold, valid bit, enable interrupts, interrupt when above threshhold
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*/
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mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE);
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#else
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/* same thing but don't enable interrupts */
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mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID);
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mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V);
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#endif
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}
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void TAUupdate(int cpu)
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{
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unsigned thrm;
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#ifdef DEBUG
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printk("TAUupdate ");
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#endif
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/* if both thresholds are crossed, the step_sizes cancel out
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* and the window winds up getting expanded twice. */
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if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */
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if(thrm & THRM1_TIN){ /* crossed low threshold */
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if (tau[cpu].low >= step_size){
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tau[cpu].low -= step_size;
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tau[cpu].high -= (step_size - window_expand);
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}
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tau[cpu].grew = 1;
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#ifdef DEBUG
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printk("low threshold crossed ");
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#endif
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}
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}
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if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */
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if(thrm & THRM1_TIN){ /* crossed high threshold */
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if (tau[cpu].high <= 127-step_size){
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tau[cpu].low += (step_size - window_expand);
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tau[cpu].high += step_size;
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}
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tau[cpu].grew = 1;
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#ifdef DEBUG
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printk("high threshold crossed ");
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#endif
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}
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}
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#ifdef DEBUG
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printk("grew = %d\n", tau[cpu].grew);
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#endif
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#ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */
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set_thresholds(cpu);
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#endif
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}
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#ifdef CONFIG_TAU_INT
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/*
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* TAU interrupts - called when we have a thermal assist unit interrupt
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* with interrupts disabled
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*/
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void TAUException(struct pt_regs * regs)
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{
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int cpu = smp_processor_id();
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irq_enter();
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tau[cpu].interrupts++;
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TAUupdate(cpu);
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irq_exit();
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}
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#endif /* CONFIG_TAU_INT */
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static void tau_timeout(void * info)
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{
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int cpu;
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unsigned long flags;
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int size;
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int shrink;
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/* disabling interrupts *should* be okay */
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local_irq_save(flags);
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cpu = smp_processor_id();
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#ifndef CONFIG_TAU_INT
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TAUupdate(cpu);
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#endif
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size = tau[cpu].high - tau[cpu].low;
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if (size > min_window && ! tau[cpu].grew) {
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/* do an exponential shrink of half the amount currently over size */
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shrink = (2 + size - min_window) / 4;
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if (shrink) {
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tau[cpu].low += shrink;
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tau[cpu].high -= shrink;
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} else { /* size must have been min_window + 1 */
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tau[cpu].low += 1;
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#if 1 /* debug */
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if ((tau[cpu].high - tau[cpu].low) != min_window){
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printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__);
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}
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#endif
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}
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}
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tau[cpu].grew = 0;
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set_thresholds(cpu);
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/*
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* Do the enable every time, since otherwise a bunch of (relatively)
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* complex sleep code needs to be added. One mtspr every time
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* tau_timeout is called is probably not a big deal.
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*
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* Enable thermal sensor and set up sample interval timer
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* need 20 us to do the compare.. until a nice 'cpu_speed' function
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* call is implemented, just assume a 500 mhz clock. It doesn't really
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* matter if we take too long for a compare since it's all interrupt
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* driven anyway.
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*
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* use a extra long time.. (60 us @ 500 mhz)
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*/
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mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E);
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local_irq_restore(flags);
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}
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static void tau_timeout_smp(unsigned long unused)
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{
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/* schedule ourselves to be run again */
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mod_timer(&tau_timer, jiffies + shrink_timer) ;
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on_each_cpu(tau_timeout, NULL, 1, 0);
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}
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/*
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* setup the TAU
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*
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* Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound.
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* Start off at zero
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*/
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int tau_initialized = 0;
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void __init TAU_init_smp(void * info)
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{
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unsigned long cpu = smp_processor_id();
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/* set these to a reasonable value and let the timer shrink the
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* window */
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tau[cpu].low = 5;
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tau[cpu].high = 120;
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set_thresholds(cpu);
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}
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int __init TAU_init(void)
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{
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/* We assume in SMP that if one CPU has TAU support, they
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* all have it --BenH
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*/
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if (!cpu_has_feature(CPU_FTR_TAU)) {
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printk("Thermal assist unit not available\n");
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tau_initialized = 0;
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return 1;
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}
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/* first, set up the window shrinking timer */
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init_timer(&tau_timer);
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tau_timer.function = tau_timeout_smp;
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tau_timer.expires = jiffies + shrink_timer;
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add_timer(&tau_timer);
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on_each_cpu(TAU_init_smp, NULL, 1, 0);
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printk("Thermal assist unit ");
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#ifdef CONFIG_TAU_INT
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printk("using interrupts, ");
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#else
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printk("using timers, ");
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#endif
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printk("shrink_timer: %d jiffies\n", shrink_timer);
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tau_initialized = 1;
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return 0;
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}
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__initcall(TAU_init);
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/*
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* return current temp
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*/
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u32 cpu_temp_both(unsigned long cpu)
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{
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return ((tau[cpu].high << 16) | tau[cpu].low);
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}
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int cpu_temp(unsigned long cpu)
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{
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return ((tau[cpu].high + tau[cpu].low) / 2);
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}
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int tau_interrupts(unsigned long cpu)
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{
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return (tau[cpu].interrupts);
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}
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