arch/x86/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 #include <linux/timex.h>
  15
  16 #include <asm/msr.h>
  17 #include <asm/processor.h>
  18
  19 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
  20                 "longrun", msg)
  21
  22 static struct cpufreq_driver    longrun_driver;
  23
  24 /**
  25  * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
  26  * values into per cent values. In TMTA microcode, the following is valid:
  27  * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
  28  */
  29 static unsigned int longrun_low_freq, longrun_high_freq;
  30
  31
  32 /**
  33  * longrun_get_policy - get the current LongRun policy
  34  * @policy: struct cpufreq_policy where current policy is written into
  35  *
  36  * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
  37  * and MSR_TMTA_LONGRUN_CTRL
  38  */
  39 static void __init longrun_get_policy(struct cpufreq_policy *policy)
  40 {
  41         u32 msr_lo, msr_hi;
  42
  43         rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
  44         dprintk("longrun flags are %x - %x\n", msr_lo, msr_hi);
  45         if (msr_lo & 0x01)
  46                 policy->policy = CPUFREQ_POLICY_PERFORMANCE;
  47         else
  48                 policy->policy = CPUFREQ_POLICY_POWERSAVE;
  49
  50         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
  51         dprintk("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
  52         msr_lo &= 0x0000007F;
  53         msr_hi &= 0x0000007F;
  54
  55         if (longrun_high_freq <= longrun_low_freq) {
  56                 /* Assume degenerate Longrun table */
  57                 policy->min = policy->max = longrun_high_freq;
  58         } else {
  59                 policy->min = longrun_low_freq + msr_lo *
  60                         ((longrun_high_freq - longrun_low_freq) / 100);
  61                 policy->max = longrun_low_freq + msr_hi *
  62                         ((longrun_high_freq - longrun_low_freq) / 100);
  63         }
  64         policy->cpu = 0;
  65 }
  66
  67
  68 /**
  69  * longrun_set_policy - sets a new CPUFreq policy
  70  * @policy: new policy
  71  *
  72  * Sets a new CPUFreq policy on LongRun-capable processors. This function
  73  * has to be called with cpufreq_driver locked.
  74  */
  75 static int longrun_set_policy(struct cpufreq_policy *policy)
  76 {
  77         u32 msr_lo, msr_hi;
  78         u32 pctg_lo, pctg_hi;
  79
  80         if (!policy)
  81                 return -EINVAL;
  82
  83         if (longrun_high_freq <= longrun_low_freq) {
  84                 /* Assume degenerate Longrun table */
  85                 pctg_lo = pctg_hi = 100;
  86         } else {
  87                 pctg_lo = (policy->min - longrun_low_freq) /
  88                         ((longrun_high_freq - longrun_low_freq) / 100);
  89                 pctg_hi = (policy->max - longrun_low_freq) /
  90                         ((longrun_high_freq - longrun_low_freq) / 100);
  91         }
  92
  93         if (pctg_hi > 100)
  94                 pctg_hi = 100;
  95         if (pctg_lo > pctg_hi)
  96                 pctg_lo = pctg_hi;
  97
  98         /* performance or economy mode */
  99         rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
 100         msr_lo &= 0xFFFFFFFE;
 101         switch (policy->policy) {
 102         case CPUFREQ_POLICY_PERFORMANCE:
 103                 msr_lo |= 0x00000001;
 104                 break;
 105         case CPUFREQ_POLICY_POWERSAVE:
 106                 break;
 107         }
 108         wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
 109
 110         /* lower and upper boundary */
 111         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 112         msr_lo &= 0xFFFFFF80;
 113         msr_hi &= 0xFFFFFF80;
 114         msr_lo |= pctg_lo;
 115         msr_hi |= pctg_hi;
 116         wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 117
 118         return 0;
 119 }
 120
 121
 122 /**
 123  * longrun_verify_poliy - verifies a new CPUFreq policy
 124  * @policy: the policy to verify
 125  *
 126  * Validates a new CPUFreq policy. This function has to be called with
 127  * cpufreq_driver locked.
 128  */
 129 static int longrun_verify_policy(struct cpufreq_policy *policy)
 130 {
 131         if (!policy)
 132                 return -EINVAL;
 133
 134         policy->cpu = 0;
 135         cpufreq_verify_within_limits(policy,
 136                 policy->cpuinfo.min_freq,
 137                 policy->cpuinfo.max_freq);
 138
 139         if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
 140             (policy->policy != CPUFREQ_POLICY_PERFORMANCE))
 141                 return -EINVAL;
 142
 143         return 0;
 144 }
 145
 146 static unsigned int longrun_get(unsigned int cpu)
 147 {
 148         u32 eax, ebx, ecx, edx;
 149
 150         if (cpu)
 151                 return 0;
 152
 153         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 154         dprintk("cpuid eax is %u\n", eax);
 155
 156         return eax * 1000;
 157 }
 158
 159 /**
 160  * longrun_determine_freqs - determines the lowest and highest possible core frequency
 161  * @low_freq: an int to put the lowest frequency into
 162  * @high_freq: an int to put the highest frequency into
 163  *
 164  * Determines the lowest and highest possible core frequencies on this CPU.
 165  * This is necessary to calculate the performance percentage according to
 166  * TMTA rules:
 167  * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
 168  */
 169 static unsigned int __init longrun_determine_freqs(unsigned int *low_freq,
 170                                                    unsigned int *high_freq)
 171 {
 172         u32 msr_lo, msr_hi;
 173         u32 save_lo, save_hi;
 174         u32 eax, ebx, ecx, edx;
 175         u32 try_hi;
 176         struct cpuinfo_x86 *c = &cpu_data(0);
 177
 178         if (!low_freq || !high_freq)
 179                 return -EINVAL;
 180
 181         if (cpu_has(c, X86_FEATURE_LRTI)) {
 182                 /* if the LongRun Table Interface is present, the
 183                  * detection is a bit easier:
 184                  * For minimum frequency, read out the maximum
 185                  * level (msr_hi), write that into "currently
 186                  * selected level", and read out the frequency.
 187                  * For maximum frequency, read out level zero.
 188                  */
 189                 /* minimum */
 190                 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
 191                 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
 192                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
 193                 *low_freq = msr_lo * 1000; /* to kHz */
 194
 195                 /* maximum */
 196                 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
 197                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
 198                 *high_freq = msr_lo * 1000; /* to kHz */
 199
 200                 dprintk("longrun table interface told %u - %u kHz\n",
 201                                 *low_freq, *high_freq);
 202
 203                 if (*low_freq > *high_freq)
 204                         *low_freq = *high_freq;
 205                 return 0;
 206         }
 207
 208         /* set the upper border to the value determined during TSC init */
 209         *high_freq = (cpu_khz / 1000);
 210         *high_freq = *high_freq * 1000;
 211         dprintk("high frequency is %u kHz\n", *high_freq);
 212
 213         /* get current borders */
 214         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 215         save_lo = msr_lo & 0x0000007F;
 216         save_hi = msr_hi & 0x0000007F;
 217
 218         /* if current perf_pctg is larger than 90%, we need to decrease the
 219          * upper limit to make the calculation more accurate.
 220          */
 221         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 222         /* try decreasing in 10% steps, some processors react only
 223          * on some barrier values */
 224         for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
 225                 /* set to 0 to try_hi perf_pctg */
 226                 msr_lo &= 0xFFFFFF80;
 227                 msr_hi &= 0xFFFFFF80;
 228                 msr_hi |= try_hi;
 229                 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 230
 231                 /* read out current core MHz and current perf_pctg */
 232                 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 233
 234                 /* restore values */
 235                 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
 236         }
 237         dprintk("percentage is %u %%, freq is %u MHz\n", ecx, eax);
 238
 239         /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
 240          * eqals
 241          * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
 242          *
 243          * high_freq * perf_pctg is stored tempoarily into "ebx".
 244          */
 245         ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
 246
 247         if ((ecx > 95) || (ecx == 0) || (eax < ebx))
 248                 return -EIO;
 249
 250         edx = ((eax - ebx) * 100) / (100 - ecx);
 251         *low_freq = edx * 1000; /* back to kHz */
 252
 253         dprintk("low frequency is %u kHz\n", *low_freq);
 254
 255         if (*low_freq > *high_freq)
 256                 *low_freq = *high_freq;
 257
 258         return 0;
 259 }
 260
 261
 262 static int __init longrun_cpu_init(struct cpufreq_policy *policy)
 263 {
 264         int result = 0;
 265
 266         /* capability check */
 267         if (policy->cpu != 0)
 268                 return -ENODEV;
 269
 270         /* detect low and high frequency */
 271         result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
 272         if (result)
 273                 return result;
 274
 275         /* cpuinfo and default policy values */
 276         policy->cpuinfo.min_freq = longrun_low_freq;
 277         policy->cpuinfo.max_freq = longrun_high_freq;
 278         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 279         longrun_get_policy(policy);
 280
 281         return 0;
 282 }
 283
 284
 285 static struct cpufreq_driver longrun_driver = {
 286         .flags          = CPUFREQ_CONST_LOOPS,
 287         .verify         = longrun_verify_policy,
 288         .setpolicy      = longrun_set_policy,
 289         .get            = longrun_get,
 290         .init           = longrun_cpu_init,
 291         .name           = "longrun",
 292         .owner          = THIS_MODULE,
 293 };
 294
 295
 296 /**
 297  * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
 298  *
 299  * Initializes the LongRun support.
 300  */
 301 static int __init longrun_init(void)
 302 {
 303         struct cpuinfo_x86 *c = &cpu_data(0);
 304
 305         if (c->x86_vendor != X86_VENDOR_TRANSMETA ||
 306             !cpu_has(c, X86_FEATURE_LONGRUN))
 307                 return -ENODEV;
 308
 309         return cpufreq_register_driver(&longrun_driver);
 310 }
 311
 312
 313 /**
 314  * longrun_exit - unregisters LongRun support
 315  */
 316 static void __exit longrun_exit(void)
 317 {
 318         cpufreq_unregister_driver(&longrun_driver);
 319 }
 320
 321
 322 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
 323 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
 324                 "Efficeon processors.");
 325 MODULE_LICENSE("GPL");
 326
 327 module_init(longrun_init);
 328 module_exit(longrun_exit);