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 #include <asm/asm-prototypes.h> 31 32 #include "setup.h" 33 34 static struct tau_temp 35 { 36 int interrupts; 37 unsigned char low; 38 unsigned char high; 39 unsigned char grew; 40 } tau[NR_CPUS]; 41 42 struct timer_list tau_timer; 43 44 #undef DEBUG 45 46 /* TODO: put these in a /proc interface, with some sanity checks, and maybe 47 * dynamic adjustment to minimize # of interrupts */ 48 /* configurable values for step size and how much to expand the window when 49 * we get an interrupt. These are based on the limit that was out of range */ 50 #define step_size 2 /* step size when temp goes out of range */ 51 #define window_expand 1 /* expand the window by this much */ 52 /* configurable values for shrinking the window */ 53 #define shrink_timer 2*HZ /* period between shrinking the window */ 54 #define min_window 2 /* minimum window size, degrees C */ 55 56 static void set_thresholds(unsigned long cpu) 57 { 58 #ifdef CONFIG_TAU_INT 59 /* 60 * setup THRM1, 61 * threshold, valid bit, enable interrupts, interrupt when below threshold 62 */ 63 mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID); 64 65 /* setup THRM2, 66 * threshold, valid bit, enable interrupts, interrupt when above threshold 67 */ 68 mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE); 69 #else 70 /* same thing but don't enable interrupts */ 71 mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID); 72 mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V); 73 #endif 74 } 75 76 static void TAUupdate(int cpu) 77 { 78 unsigned thrm; 79 80 #ifdef DEBUG 81 printk("TAUupdate "); 82 #endif 83 84 /* if both thresholds are crossed, the step_sizes cancel out 85 * and the window winds up getting expanded twice. */ 86 if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */ 87 if(thrm & THRM1_TIN){ /* crossed low threshold */ 88 if (tau[cpu].low >= step_size){ 89 tau[cpu].low -= step_size; 90 tau[cpu].high -= (step_size - window_expand); 91 } 92 tau[cpu].grew = 1; 93 #ifdef DEBUG 94 printk("low threshold crossed "); 95 #endif 96 } 97 } 98 if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */ 99 if(thrm & THRM1_TIN){ /* crossed high threshold */ 100 if (tau[cpu].high <= 127-step_size){ 101 tau[cpu].low += (step_size - window_expand); 102 tau[cpu].high += step_size; 103 } 104 tau[cpu].grew = 1; 105 #ifdef DEBUG 106 printk("high threshold crossed "); 107 #endif 108 } 109 } 110 111 #ifdef DEBUG 112 printk("grew = %d\n", tau[cpu].grew); 113 #endif 114 115 #ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */ 116 set_thresholds(cpu); 117 #endif 118 119 } 120 121 #ifdef CONFIG_TAU_INT 122 /* 123 * TAU interrupts - called when we have a thermal assist unit interrupt 124 * with interrupts disabled 125 */ 126 127 void TAUException(struct pt_regs * regs) 128 { 129 int cpu = smp_processor_id(); 130 131 irq_enter(); 132 tau[cpu].interrupts++; 133 134 TAUupdate(cpu); 135 136 irq_exit(); 137 } 138 #endif /* CONFIG_TAU_INT */ 139 140 static void tau_timeout(void * info) 141 { 142 int cpu; 143 unsigned long flags; 144 int size; 145 int shrink; 146 147 /* disabling interrupts *should* be okay */ 148 local_irq_save(flags); 149 cpu = smp_processor_id(); 150 151 #ifndef CONFIG_TAU_INT 152 TAUupdate(cpu); 153 #endif 154 155 size = tau[cpu].high - tau[cpu].low; 156 if (size > min_window && ! tau[cpu].grew) { 157 /* do an exponential shrink of half the amount currently over size */ 158 shrink = (2 + size - min_window) / 4; 159 if (shrink) { 160 tau[cpu].low += shrink; 161 tau[cpu].high -= shrink; 162 } else { /* size must have been min_window + 1 */ 163 tau[cpu].low += 1; 164 #if 1 /* debug */ 165 if ((tau[cpu].high - tau[cpu].low) != min_window){ 166 printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__); 167 } 168 #endif 169 } 170 } 171 172 tau[cpu].grew = 0; 173 174 set_thresholds(cpu); 175 176 /* 177 * Do the enable every time, since otherwise a bunch of (relatively) 178 * complex sleep code needs to be added. One mtspr every time 179 * tau_timeout is called is probably not a big deal. 180 * 181 * Enable thermal sensor and set up sample interval timer 182 * need 20 us to do the compare.. until a nice 'cpu_speed' function 183 * call is implemented, just assume a 500 mhz clock. It doesn't really 184 * matter if we take too long for a compare since it's all interrupt 185 * driven anyway. 186 * 187 * use a extra long time.. (60 us @ 500 mhz) 188 */ 189 mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E); 190 191 local_irq_restore(flags); 192 } 193 194 static void tau_timeout_smp(struct timer_list *unused) 195 { 196 197 /* schedule ourselves to be run again */ 198 mod_timer(&tau_timer, jiffies + shrink_timer) ; 199 on_each_cpu(tau_timeout, NULL, 0); 200 } 201 202 /* 203 * setup the TAU 204 * 205 * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound. 206 * Start off at zero 207 */ 208 209 int tau_initialized = 0; 210 211 static void __init TAU_init_smp(void *info) 212 { 213 unsigned long cpu = smp_processor_id(); 214 215 /* set these to a reasonable value and let the timer shrink the 216 * window */ 217 tau[cpu].low = 5; 218 tau[cpu].high = 120; 219 220 set_thresholds(cpu); 221 } 222 223 static int __init TAU_init(void) 224 { 225 /* We assume in SMP that if one CPU has TAU support, they 226 * all have it --BenH 227 */ 228 if (!cpu_has_feature(CPU_FTR_TAU)) { 229 printk("Thermal assist unit not available\n"); 230 tau_initialized = 0; 231 return 1; 232 } 233 234 235 /* first, set up the window shrinking timer */ 236 timer_setup(&tau_timer, tau_timeout_smp, 0); 237 tau_timer.expires = jiffies + shrink_timer; 238 add_timer(&tau_timer); 239 240 on_each_cpu(TAU_init_smp, NULL, 0); 241 242 printk("Thermal assist unit "); 243 #ifdef CONFIG_TAU_INT 244 printk("using interrupts, "); 245 #else 246 printk("using timers, "); 247 #endif 248 printk("shrink_timer: %d jiffies\n", shrink_timer); 249 tau_initialized = 1; 250 251 return 0; 252 } 253 254 __initcall(TAU_init); 255 256 /* 257 * return current temp 258 */ 259 260 u32 cpu_temp_both(unsigned long cpu) 261 { 262 return ((tau[cpu].high << 16) | tau[cpu].low); 263 } 264 265 u32 cpu_temp(unsigned long cpu) 266 { 267 return ((tau[cpu].high + tau[cpu].low) / 2); 268 } 269 270 u32 tau_interrupts(unsigned long cpu) 271 { 272 return (tau[cpu].interrupts); 273 } 274