release/src-rt-6.x.4708/linux/linux-2.6.36/arch/powerpc/kernel/tau_6xx.c

   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/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
  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 threshold
  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 ((tau[cpu].high - tau[cpu].low) != min_window){
 161                                 printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__);
 162                         }
 163                 }
 164         }
 165
 166         tau[cpu].grew = 0;
 167
 168         set_thresholds(cpu);
 169
 170         /*
 171          * Do the enable every time, since otherwise a bunch of (relatively)
 172          * complex sleep code needs to be added. One mtspr every time
 173          * tau_timeout is called is probably not a big deal.
 174          *
 175          * Enable thermal sensor and set up sample interval timer
 176          * need 20 us to do the compare.. until a nice 'cpu_speed' function
 177          * call is implemented, just assume a 500 mhz clock. It doesn't really
 178          * matter if we take too long for a compare since it's all interrupt
 179          * driven anyway.
 180          *
 181          * use a extra long time.. (60 us @ 500 mhz)
 182          */
 183         mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E);
 184
 185         local_irq_restore(flags);
 186 }
 187
 188 static void tau_timeout_smp(unsigned long unused)
 189 {
 190
 191         /* schedule ourselves to be run again */
 192         mod_timer(&tau_timer, jiffies + shrink_timer) ;
 193         on_each_cpu(tau_timeout, NULL, 0);
 194 }
 195
 196 /*
 197  * setup the TAU
 198  *
 199  * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound.
 200  * Start off at zero
 201  */
 202
 203 int tau_initialized = 0;
 204
 205 void __init TAU_init_smp(void * info)
 206 {
 207         unsigned long cpu = smp_processor_id();
 208
 209         /* set these to a reasonable value and let the timer shrink the
 210          * window */
 211         tau[cpu].low = 5;
 212         tau[cpu].high = 120;
 213
 214         set_thresholds(cpu);
 215 }
 216
 217 int __init TAU_init(void)
 218 {
 219         /* We assume in SMP that if one CPU has TAU support, they
 220          * all have it --BenH
 221          */
 222         if (!cpu_has_feature(CPU_FTR_TAU)) {
 223                 printk("Thermal assist unit not available\n");
 224                 tau_initialized = 0;
 225                 return 1;
 226         }
 227
 228
 229         /* first, set up the window shrinking timer */
 230         init_timer(&tau_timer);
 231         tau_timer.function = tau_timeout_smp;
 232         tau_timer.expires = jiffies + shrink_timer;
 233         add_timer(&tau_timer);
 234
 235         on_each_cpu(TAU_init_smp, NULL, 0);
 236
 237         printk("Thermal assist unit ");
 238 #ifdef CONFIG_TAU_INT
 239         printk("using interrupts, ");
 240 #else
 241         printk("using timers, ");
 242 #endif
 243         printk("shrink_timer: %d jiffies\n", shrink_timer);
 244         tau_initialized = 1;
 245
 246         return 0;
 247 }
 248
 249 __initcall(TAU_init);
 250
 251 /*
 252  * return current temp
 253  */
 254
 255 u32 cpu_temp_both(unsigned long cpu)
 256 {
 257         return ((tau[cpu].high << 16) | tau[cpu].low);
 258 }
 259
 260 int cpu_temp(unsigned long cpu)
 261 {
 262         return ((tau[cpu].high + tau[cpu].low) / 2);
 263 }
 264
 265 int tau_interrupts(unsigned long cpu)
 266 {
 267         return (tau[cpu].interrupts);
 268 }