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 1 /* debug */ 161 if ((tau[cpu].high - tau[cpu].low) != min_window){ 162 printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__); 163 } 164 #endif 165 } 166 } 167 168 tau[cpu].grew = 0; 169 170 set_thresholds(cpu); 171 172 /* 173 * Do the enable every time, since otherwise a bunch of (relatively) 174 * complex sleep code needs to be added. One mtspr every time 175 * tau_timeout is called is probably not a big deal. 176 * 177 * Enable thermal sensor and set up sample interval timer 178 * need 20 us to do the compare.. until a nice 'cpu_speed' function 179 * call is implemented, just assume a 500 mhz clock. It doesn't really 180 * matter if we take too long for a compare since it's all interrupt 181 * driven anyway. 182 * 183 * use a extra long time.. (60 us @ 500 mhz) 184 */ 185 mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E); 186 187 local_irq_restore(flags); 188 } 189 190 static void tau_timeout_smp(unsigned long unused) 191 { 192 193 /* schedule ourselves to be run again */ 194 mod_timer(&tau_timer, jiffies + shrink_timer) ; 195 on_each_cpu(tau_timeout, NULL, 0); 196 } 197 198 /* 199 * setup the TAU 200 * 201 * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound. 202 * Start off at zero 203 */ 204 205 int tau_initialized = 0; 206 207 void __init TAU_init_smp(void * info) 208 { 209 unsigned long cpu = smp_processor_id(); 210 211 /* set these to a reasonable value and let the timer shrink the 212 * window */ 213 tau[cpu].low = 5; 214 tau[cpu].high = 120; 215 216 set_thresholds(cpu); 217 } 218 219 int __init TAU_init(void) 220 { 221 /* We assume in SMP that if one CPU has TAU support, they 222 * all have it --BenH 223 */ 224 if (!cpu_has_feature(CPU_FTR_TAU)) { 225 printk("Thermal assist unit not available\n"); 226 tau_initialized = 0; 227 return 1; 228 } 229 230 231 /* first, set up the window shrinking timer */ 232 init_timer(&tau_timer); 233 tau_timer.function = tau_timeout_smp; 234 tau_timer.expires = jiffies + shrink_timer; 235 add_timer(&tau_timer); 236 237 on_each_cpu(TAU_init_smp, NULL, 0); 238 239 printk("Thermal assist unit "); 240 #ifdef CONFIG_TAU_INT 241 printk("using interrupts, "); 242 #else 243 printk("using timers, "); 244 #endif 245 printk("shrink_timer: %d jiffies\n", shrink_timer); 246 tau_initialized = 1; 247 248 return 0; 249 } 250 251 __initcall(TAU_init); 252 253 /* 254 * return current temp 255 */ 256 257 u32 cpu_temp_both(unsigned long cpu) 258 { 259 return ((tau[cpu].high << 16) | tau[cpu].low); 260 } 261 262 int cpu_temp(unsigned long cpu) 263 { 264 return ((tau[cpu].high + tau[cpu].low) / 2); 265 } 266 267 int tau_interrupts(unsigned long cpu) 268 { 269 return (tau[cpu].interrupts); 270 } 271