1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * temp.c Thermal management for cpu's with Thermal Assist Units 4 * 5 * Written by Troy Benjegerdes <hozer@drgw.net> 6 * 7 * TODO: 8 * dynamic power management to limit peak CPU temp (using ICTC) 9 * calibration??? 10 * 11 * Silly, crazy ideas: use cpu load (from scheduler) and ICTC to extend battery 12 * life in portables, and add a 'performance/watt' metric somewhere in /proc 13 */ 14 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/io.h> 25 #include <asm/reg.h> 26 #include <asm/nvram.h> 27 #include <asm/cache.h> 28 #include <asm/8xx_immap.h> 29 #include <asm/machdep.h> 30 31 static struct tau_temp 32 { 33 int interrupts; 34 unsigned char low; 35 unsigned char high; 36 unsigned char grew; 37 } tau[NR_CPUS]; 38 39 struct timer_list tau_timer; 40 41 #undef DEBUG 42 43 /* TODO: put these in a /proc interface, with some sanity checks, and maybe 44 * dynamic adjustment to minimize # of interrupts */ 45 /* configurable values for step size and how much to expand the window when 46 * we get an interrupt. These are based on the limit that was out of range */ 47 #define step_size 2 /* step size when temp goes out of range */ 48 #define window_expand 1 /* expand the window by this much */ 49 /* configurable values for shrinking the window */ 50 #define shrink_timer 2*HZ /* period between shrinking the window */ 51 #define min_window 2 /* minimum window size, degrees C */ 52 53 void set_thresholds(unsigned long cpu) 54 { 55 #ifdef CONFIG_TAU_INT 56 /* 57 * setup THRM1, 58 * threshold, valid bit, enable interrupts, interrupt when below threshold 59 */ 60 mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID); 61 62 /* setup THRM2, 63 * threshold, valid bit, enable interrupts, interrupt when above threshold 64 */ 65 mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE); 66 #else 67 /* same thing but don't enable interrupts */ 68 mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID); 69 mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V); 70 #endif 71 } 72 73 void TAUupdate(int cpu) 74 { 75 unsigned thrm; 76 77 #ifdef DEBUG 78 printk("TAUupdate "); 79 #endif 80 81 /* if both thresholds are crossed, the step_sizes cancel out 82 * and the window winds up getting expanded twice. */ 83 if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */ 84 if(thrm & THRM1_TIN){ /* crossed low threshold */ 85 if (tau[cpu].low >= step_size){ 86 tau[cpu].low -= step_size; 87 tau[cpu].high -= (step_size - window_expand); 88 } 89 tau[cpu].grew = 1; 90 #ifdef DEBUG 91 printk("low threshold crossed "); 92 #endif 93 } 94 } 95 if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */ 96 if(thrm & THRM1_TIN){ /* crossed high threshold */ 97 if (tau[cpu].high <= 127-step_size){ 98 tau[cpu].low += (step_size - window_expand); 99 tau[cpu].high += step_size; 100 } 101 tau[cpu].grew = 1; 102 #ifdef DEBUG 103 printk("high threshold crossed "); 104 #endif 105 } 106 } 107 108 #ifdef DEBUG 109 printk("grew = %d\n", tau[cpu].grew); 110 #endif 111 112 #ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */ 113 set_thresholds(cpu); 114 #endif 115 116 } 117 118 #ifdef CONFIG_TAU_INT 119 /* 120 * TAU interrupts - called when we have a thermal assist unit interrupt 121 * with interrupts disabled 122 */ 123 124 void TAUException(struct pt_regs * regs) 125 { 126 int cpu = smp_processor_id(); 127 128 irq_enter(); 129 tau[cpu].interrupts++; 130 131 TAUupdate(cpu); 132 133 irq_exit(); 134 } 135 #endif /* CONFIG_TAU_INT */ 136 137 static void tau_timeout(void * info) 138 { 139 int cpu; 140 unsigned long flags; 141 int size; 142 int shrink; 143 144 /* disabling interrupts *should* be okay */ 145 local_irq_save(flags); 146 cpu = smp_processor_id(); 147 148 #ifndef CONFIG_TAU_INT 149 TAUupdate(cpu); 150 #endif 151 152 size = tau[cpu].high - tau[cpu].low; 153 if (size > min_window && ! tau[cpu].grew) { 154 /* do an exponential shrink of half the amount currently over size */ 155 shrink = (2 + size - min_window) / 4; 156 if (shrink) { 157 tau[cpu].low += shrink; 158 tau[cpu].high -= shrink; 159 } else { /* size must have been min_window + 1 */ 160 tau[cpu].low += 1; 161 #if 1 /* debug */ 162 if ((tau[cpu].high - tau[cpu].low) != min_window){ 163 printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__); 164 } 165 #endif 166 } 167 } 168 169 tau[cpu].grew = 0; 170 171 set_thresholds(cpu); 172 173 /* 174 * Do the enable every time, since otherwise a bunch of (relatively) 175 * complex sleep code needs to be added. One mtspr every time 176 * tau_timeout is called is probably not a big deal. 177 * 178 * Enable thermal sensor and set up sample interval timer 179 * need 20 us to do the compare.. until a nice 'cpu_speed' function 180 * call is implemented, just assume a 500 mhz clock. It doesn't really 181 * matter if we take too long for a compare since it's all interrupt 182 * driven anyway. 183 * 184 * use a extra long time.. (60 us @ 500 mhz) 185 */ 186 mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E); 187 188 local_irq_restore(flags); 189 } 190 191 static void tau_timeout_smp(struct timer_list *unused) 192 { 193 194 /* schedule ourselves to be run again */ 195 mod_timer(&tau_timer, jiffies + shrink_timer) ; 196 on_each_cpu(tau_timeout, NULL, 0); 197 } 198 199 /* 200 * setup the TAU 201 * 202 * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound. 203 * Start off at zero 204 */ 205 206 int tau_initialized = 0; 207 208 void __init TAU_init_smp(void * info) 209 { 210 unsigned long cpu = smp_processor_id(); 211 212 /* set these to a reasonable value and let the timer shrink the 213 * window */ 214 tau[cpu].low = 5; 215 tau[cpu].high = 120; 216 217 set_thresholds(cpu); 218 } 219 220 int __init TAU_init(void) 221 { 222 /* We assume in SMP that if one CPU has TAU support, they 223 * all have it --BenH 224 */ 225 if (!cpu_has_feature(CPU_FTR_TAU)) { 226 printk("Thermal assist unit not available\n"); 227 tau_initialized = 0; 228 return 1; 229 } 230 231 232 /* first, set up the window shrinking timer */ 233 timer_setup(&tau_timer, tau_timeout_smp, 0); 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