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