Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 threshhold |
| 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, 1, 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, 1, 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 | } |