arch/i386/kernel/cpu/cpufreq/longrun.c

   1 /*
   2  * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
   3  *
   4  *  Licensed under the terms of the GNU GPL License version 2.
   5  *
   6  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/slab.h>
  13 #include <linux/cpufreq.h>
  14
  15 #include <asm/msr.h>
  16 #include <asm/processor.h>
  17 #include <asm/timex.h>
  18
  19 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "longrun", msg)
  20
  21 static struct cpufreq_driver    longrun_driver;
  22
  23 /**
  24  * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
  25  * values into per cent values. In TMTA microcode, the following is valid:
  26  * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
  27  */
  28 static unsigned int longrun_low_freq, longrun_high_freq;
  29
  30
  31 /**
  32  * longrun_get_policy - get the current LongRun policy
  33  * @policy: struct cpufreq_policy where current policy is written into
  34  *
  35  * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
  36  * and MSR_TMTA_LONGRUN_CTRL
  37  */
  38 static void __init longrun_get_policy(struct cpufreq_policy *policy)
  39 {
  40         u32 msr_lo, msr_hi;
  41
  42         rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
  43         dprintk("longrun flags are %x - %x\n", msr_lo, msr_hi);
  44         if (msr_lo & 0x01)
  45                 policy->policy = CPUFREQ_POLICY_PERFORMANCE;
  46         else
  47                 policy->policy = CPUFREQ_POLICY_POWERSAVE;
  48
  49         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
  50         dprintk("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
  51         msr_lo &= 0x0000007F;
  52         msr_hi &= 0x0000007F;
  53
  54         if ( longrun_high_freq <= longrun_low_freq ) {
  55                 /* Assume degenerate Longrun table */
  56                 policy->min = policy->max = longrun_high_freq;
  57         } else {
  58                 policy->min = longrun_low_freq + msr_lo *
  59                         ((longrun_high_freq - longrun_low_freq) / 100);
  60                 policy->max = longrun_low_freq + msr_hi *
  61                         ((longrun_high_freq - longrun_low_freq) / 100);
  62         }
  63         policy->cpu = 0;
  64 }
  65
  66
  67 /**
  68  * longrun_set_policy - sets a new CPUFreq policy
  69  * @policy: new policy
  70  *
  71  * Sets a new CPUFreq policy on LongRun-capable processors. This function
  72  * has to be called with cpufreq_driver locked.
  73  */
  74 static int longrun_set_policy(struct cpufreq_policy *policy)
  75 {
  76         u32 msr_lo, msr_hi;
  77         u32 pctg_lo, pctg_hi;
  78
  79         if (!policy)
  80                 return -EINVAL;
  81
  82         if ( longrun_high_freq <= longrun_low_freq ) {
  83                 /* Assume degenerate Longrun table */
  84                 pctg_lo = pctg_hi = 100;
  85         } else {
  86                 pctg_lo = (policy->min - longrun_low_freq) /
  87                         ((longrun_high_freq - longrun_low_freq) / 100);
  88                 pctg_hi = (policy->max - longrun_low_freq) /
  89                         ((longrun_high_freq - longrun_low_freq) / 100);
  90         }
  91
  92         if (pctg_hi > 100)
  93                 pctg_hi = 100;
  94         if (pctg_lo > pctg_hi)
  95                 pctg_lo = pctg_hi;
  96
  97         /* performance or economy mode */
  98         rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
  99         msr_lo &= 0xFFFFFFFE;
 100         switch (policy->policy) {
 101         case CPUFREQ_POLICY_PERFORMANCE:
 102                 msr_lo |= 0x00000001;
 103                 break;
 104         case CPUFREQ_POLICY_POWERSAVE:
 105                 break;
 106         }
 107         wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
 108
 109         /* lower and upper boundary */
 110         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 111         msr_lo &= 0xFFFFFF80;
 112         msr_hi &= 0xFFFFFF80;
 113         msr_lo |= pctg_lo;
 114         msr_hi |= pctg_hi;
 115         wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 116
 117         return 0;
 118 }
 119
 120
 121 /**
 122  * longrun_verify_poliy - verifies a new CPUFreq policy
 123  * @policy: the policy to verify
 124  *
 125  * Validates a new CPUFreq policy. This function has to be called with
 126  * cpufreq_driver locked.
 127  */
 128 static int longrun_verify_policy(struct cpufreq_policy *policy)
 129 {
 130         if (!policy)
 131                 return -EINVAL;
 132
 133         policy->cpu = 0;
 134         cpufreq_verify_within_limits(policy,
 135                 policy->cpuinfo.min_freq,
 136                 policy->cpuinfo.max_freq);
 137
 138         if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
 139             (policy->policy != CPUFREQ_POLICY_PERFORMANCE))
 140                 return -EINVAL;
 141
 142         return 0;
 143 }
 144
 145 static unsigned int longrun_get(unsigned int cpu)
 146 {
 147         u32 eax, ebx, ecx, edx;
 148
 149         if (cpu)
 150                 return 0;
 151
 152         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 153         dprintk("cpuid eax is %u\n", eax);
 154
 155         return (eax * 1000);
 156 }
 157
 158 /**
 159  * longrun_determine_freqs - determines the lowest and highest possible core frequency
 160  * @low_freq: an int to put the lowest frequency into
 161  * @high_freq: an int to put the highest frequency into
 162  *
 163  * Determines the lowest and highest possible core frequencies on this CPU.
 164  * This is necessary to calculate the performance percentage according to
 165  * TMTA rules:
 166  * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
 167  */
 168 static unsigned int __init longrun_determine_freqs(unsigned int *low_freq,
 169                                                    unsigned int *high_freq)
 170 {
 171         u32 msr_lo, msr_hi;
 172         u32 save_lo, save_hi;
 173         u32 eax, ebx, ecx, edx;
 174         u32 try_hi;
 175         struct cpuinfo_x86 *c = cpu_data;
 176
 177         if (!low_freq || !high_freq)
 178                 return -EINVAL;
 179
 180         if (cpu_has(c, X86_FEATURE_LRTI)) {
 181                 /* if the LongRun Table Interface is present, the
 182                  * detection is a bit easier:
 183                  * For minimum frequency, read out the maximum
 184                  * level (msr_hi), write that into "currently
 185                  * selected level", and read out the frequency.
 186                  * For maximum frequency, read out level zero.
 187                  */
 188                 /* minimum */
 189                 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
 190                 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
 191                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
 192                 *low_freq = msr_lo * 1000; /* to kHz */
 193
 194                 /* maximum */
 195                 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
 196                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
 197                 *high_freq = msr_lo * 1000; /* to kHz */
 198
 199                 dprintk("longrun table interface told %u - %u kHz\n", *low_freq, *high_freq);
 200
 201                 if (*low_freq > *high_freq)
 202                         *low_freq = *high_freq;
 203                 return 0;
 204         }
 205
 206         /* set the upper border to the value determined during TSC init */
 207         *high_freq = (cpu_khz / 1000);
 208         *high_freq = *high_freq * 1000;
 209         dprintk("high frequency is %u kHz\n", *high_freq);
 210
 211         /* get current borders */
 212         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 213         save_lo = msr_lo & 0x0000007F;
 214         save_hi = msr_hi & 0x0000007F;
 215
 216         /* if current perf_pctg is larger than 90%, we need to decrease the
 217          * upper limit to make the calculation more accurate.
 218          */
 219         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 220         /* try decreasing in 10% steps, some processors react only
 221          * on some barrier values */
 222         for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -=10) {
 223                 /* set to 0 to try_hi perf_pctg */
 224                 msr_lo &= 0xFFFFFF80;
 225                 msr_hi &= 0xFFFFFF80;
 226                 msr_hi |= try_hi;
 227                 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 228
 229                 /* read out current core MHz and current perf_pctg */
 230                 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 231
 232                 /* restore values */
 233                 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
 234         }
 235         dprintk("percentage is %u %%, freq is %u MHz\n", ecx, eax);
 236
 237         /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
 238          * eqals
 239          * low_freq * ( 1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
 240          *
 241          * high_freq * perf_pctg is stored tempoarily into "ebx".
 242          */
 243         ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
 244
 245         if ((ecx > 95) || (ecx == 0) || (eax < ebx))
 246                 return -EIO;
 247
 248         edx = (eax - ebx) / (100 - ecx);
 249         *low_freq = edx * 1000; /* back to kHz */
 250
 251         dprintk("low frequency is %u kHz\n", *low_freq);
 252
 253         if (*low_freq > *high_freq)
 254                 *low_freq = *high_freq;
 255
 256         return 0;
 257 }
 258
 259
 260 static int __init longrun_cpu_init(struct cpufreq_policy *policy)
 261 {
 262         int result = 0;
 263
 264         /* capability check */
 265         if (policy->cpu != 0)
 266                 return -ENODEV;
 267
 268         /* detect low and high frequency */
 269         result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
 270         if (result)
 271                 return result;
 272
 273         /* cpuinfo and default policy values */
 274         policy->cpuinfo.min_freq = longrun_low_freq;
 275         policy->cpuinfo.max_freq = longrun_high_freq;
 276         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 277         longrun_get_policy(policy);
 278
 279         return 0;
 280 }
 281
 282
 283 static struct cpufreq_driver longrun_driver = {
 284         .flags          = CPUFREQ_CONST_LOOPS,
 285         .verify         = longrun_verify_policy,
 286         .setpolicy      = longrun_set_policy,
 287         .get            = longrun_get,
 288         .init           = longrun_cpu_init,
 289         .name           = "longrun",
 290         .owner          = THIS_MODULE,
 291 };
 292
 293
 294 /**
 295  * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
 296  *
 297  * Initializes the LongRun support.
 298  */
 299 static int __init longrun_init(void)
 300 {
 301         struct cpuinfo_x86 *c = cpu_data;
 302
 303         if (c->x86_vendor != X86_VENDOR_TRANSMETA ||
 304             !cpu_has(c, X86_FEATURE_LONGRUN))
 305                 return -ENODEV;
 306
 307         return cpufreq_register_driver(&longrun_driver);
 308 }
 309
 310
 311 /**
 312  * longrun_exit - unregisters LongRun support
 313  */
 314 static void __exit longrun_exit(void)
 315 {
 316         cpufreq_unregister_driver(&longrun_driver);
 317 }
 318
 319
 320 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>");
 321 MODULE_DESCRIPTION ("LongRun driver for Transmeta Crusoe and Efficeon processors.");
 322 MODULE_LICENSE ("GPL");
 323
 324 module_init(longrun_init);
 325 module_exit(longrun_exit);