arch/x86/kernel/cpu/cpufreq/e_powersaver.c

   1 /*
   2  *  Based on documentation provided by Dave Jones. Thanks!
   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/cpufreq.h>
  13 #include <linux/ioport.h>
  14 #include <linux/slab.h>
  15 #include <linux/timex.h>
  16 #include <linux/io.h>
  17 #include <linux/delay.h>
  18
  19 #include <asm/msr.h>
  20 #include <asm/tsc.h>
  21
  22 #define EPS_BRAND_C7M   0
  23 #define EPS_BRAND_C7    1
  24 #define EPS_BRAND_EDEN  2
  25 #define EPS_BRAND_C3    3
  26 #define EPS_BRAND_C7D   4
  27
  28 struct eps_cpu_data {
  29         u32 fsb;
  30         struct cpufreq_frequency_table freq_table[];
  31 };
  32
  33 static struct eps_cpu_data *eps_cpu[NR_CPUS];
  34
  35
  36 static unsigned int eps_get(unsigned int cpu)
  37 {
  38         struct eps_cpu_data *centaur;
  39         u32 lo, hi;
  40
  41         if (cpu)
  42                 return 0;
  43         centaur = eps_cpu[cpu];
  44         if (centaur == NULL)
  45                 return 0;
  46
  47         /* Return current frequency */
  48         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  49         return centaur->fsb * ((lo >> 8) & 0xff);
  50 }
  51
  52 static int eps_set_state(struct eps_cpu_data *centaur,
  53                          unsigned int cpu,
  54                          u32 dest_state)
  55 {
  56         struct cpufreq_freqs freqs;
  57         u32 lo, hi;
  58         int err = 0;
  59         int i;
  60
  61         freqs.old = eps_get(cpu);
  62         freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
  63         freqs.cpu = cpu;
  64         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  65
  66         /* Wait while CPU is busy */
  67         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  68         i = 0;
  69         while (lo & ((1 << 16) | (1 << 17))) {
  70                 udelay(16);
  71                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  72                 i++;
  73                 if (unlikely(i > 64)) {
  74                         err = -ENODEV;
  75                         goto postchange;
  76                 }
  77         }
  78         /* Set new multiplier and voltage */
  79         wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
  80         /* Wait until transition end */
  81         i = 0;
  82         do {
  83                 udelay(16);
  84                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  85                 i++;
  86                 if (unlikely(i > 64)) {
  87                         err = -ENODEV;
  88                         goto postchange;
  89                 }
  90         } while (lo & ((1 << 16) | (1 << 17)));
  91
  92         /* Return current frequency */
  93 postchange:
  94         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  95         freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
  96
  97 #ifdef DEBUG
  98         {
  99         u8 current_multiplier, current_voltage;
 100
 101         /* Print voltage and multiplier */
 102         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 103         current_voltage = lo & 0xff;
 104         printk(KERN_INFO "eps: Current voltage = %dmV\n",
 105                 current_voltage * 16 + 700);
 106         current_multiplier = (lo >> 8) & 0xff;
 107         printk(KERN_INFO "eps: Current multiplier = %d\n",
 108                 current_multiplier);
 109         }
 110 #endif
 111         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 112         return err;
 113 }
 114
 115 static int eps_target(struct cpufreq_policy *policy,
 116                                unsigned int target_freq,
 117                                unsigned int relation)
 118 {
 119         struct eps_cpu_data *centaur;
 120         unsigned int newstate = 0;
 121         unsigned int cpu = policy->cpu;
 122         unsigned int dest_state;
 123         int ret;
 124
 125         if (unlikely(eps_cpu[cpu] == NULL))
 126                 return -ENODEV;
 127         centaur = eps_cpu[cpu];
 128
 129         if (unlikely(cpufreq_frequency_table_target(policy,
 130                         &eps_cpu[cpu]->freq_table[0],
 131                         target_freq,
 132                         relation,
 133                         &newstate))) {
 134                 return -EINVAL;
 135         }
 136
 137         /* Make frequency transition */
 138         dest_state = centaur->freq_table[newstate].index & 0xffff;
 139         ret = eps_set_state(centaur, cpu, dest_state);
 140         if (ret)
 141                 printk(KERN_ERR "eps: Timeout!\n");
 142         return ret;
 143 }
 144
 145 static int eps_verify(struct cpufreq_policy *policy)
 146 {
 147         return cpufreq_frequency_table_verify(policy,
 148                         &eps_cpu[policy->cpu]->freq_table[0]);
 149 }
 150
 151 static int eps_cpu_init(struct cpufreq_policy *policy)
 152 {
 153         unsigned int i;
 154         u32 lo, hi;
 155         u64 val;
 156         u8 current_multiplier, current_voltage;
 157         u8 max_multiplier, max_voltage;
 158         u8 min_multiplier, min_voltage;
 159         u8 brand = 0;
 160         u32 fsb;
 161         struct eps_cpu_data *centaur;
 162         struct cpuinfo_x86 *c = &cpu_data(0);
 163         struct cpufreq_frequency_table *f_table;
 164         int k, step, voltage;
 165         int ret;
 166         int states;
 167
 168         if (policy->cpu != 0)
 169                 return -ENODEV;
 170
 171         /* Check brand */
 172         printk(KERN_INFO "eps: Detected VIA ");
 173
 174         switch (c->x86_model) {
 175         case 10:
 176                 rdmsr(0x1153, lo, hi);
 177                 brand = (((lo >> 2) ^ lo) >> 18) & 3;
 178                 printk(KERN_CONT "Model A ");
 179                 break;
 180         case 13:
 181                 rdmsr(0x1154, lo, hi);
 182                 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
 183                 printk(KERN_CONT "Model D ");
 184                 break;
 185         }
 186
 187         switch (brand) {
 188         case EPS_BRAND_C7M:
 189                 printk(KERN_CONT "C7-M\n");
 190                 break;
 191         case EPS_BRAND_C7:
 192                 printk(KERN_CONT "C7\n");
 193                 break;
 194         case EPS_BRAND_EDEN:
 195                 printk(KERN_CONT "Eden\n");
 196                 break;
 197         case EPS_BRAND_C7D:
 198                 printk(KERN_CONT "C7-D\n");
 199                 break;
 200         case EPS_BRAND_C3:
 201                 printk(KERN_CONT "C3\n");
 202                 return -ENODEV;
 203                 break;
 204         }
 205         /* Enable Enhanced PowerSaver */
 206         rdmsrl(MSR_IA32_MISC_ENABLE, val);
 207         if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 208                 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
 209                 wrmsrl(MSR_IA32_MISC_ENABLE, val);
 210                 /* Can be locked at 0 */
 211                 rdmsrl(MSR_IA32_MISC_ENABLE, val);
 212                 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 213                         printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
 214                         return -ENODEV;
 215                 }
 216         }
 217
 218         /* Print voltage and multiplier */
 219         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 220         current_voltage = lo & 0xff;
 221         printk(KERN_INFO "eps: Current voltage = %dmV\n",
 222                         current_voltage * 16 + 700);
 223         current_multiplier = (lo >> 8) & 0xff;
 224         printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
 225
 226         /* Print limits */
 227         max_voltage = hi & 0xff;
 228         printk(KERN_INFO "eps: Highest voltage = %dmV\n",
 229                         max_voltage * 16 + 700);
 230         max_multiplier = (hi >> 8) & 0xff;
 231         printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
 232         min_voltage = (hi >> 16) & 0xff;
 233         printk(KERN_INFO "eps: Lowest voltage = %dmV\n",
 234                         min_voltage * 16 + 700);
 235         min_multiplier = (hi >> 24) & 0xff;
 236         printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
 237
 238         /* Sanity checks */
 239         if (current_multiplier == 0 || max_multiplier == 0
 240             || min_multiplier == 0)
 241                 return -EINVAL;
 242         if (current_multiplier > max_multiplier
 243             || max_multiplier <= min_multiplier)
 244                 return -EINVAL;
 245         if (current_voltage > 0x1f || max_voltage > 0x1f)
 246                 return -EINVAL;
 247         if (max_voltage < min_voltage)
 248                 return -EINVAL;
 249
 250         /* Calc FSB speed */
 251         fsb = cpu_khz / current_multiplier;
 252         /* Calc number of p-states supported */
 253         if (brand == EPS_BRAND_C7M)
 254                 states = max_multiplier - min_multiplier + 1;
 255         else
 256                 states = 2;
 257
 258         /* Allocate private data and frequency table for current cpu */
 259         centaur = kzalloc(sizeof(struct eps_cpu_data)
 260                     + (states + 1) * sizeof(struct cpufreq_frequency_table),
 261                     GFP_KERNEL);
 262         if (!centaur)
 263                 return -ENOMEM;
 264         eps_cpu[0] = centaur;
 265
 266         /* Copy basic values */
 267         centaur->fsb = fsb;
 268
 269         /* Fill frequency and MSR value table */
 270         f_table = &centaur->freq_table[0];
 271         if (brand != EPS_BRAND_C7M) {
 272                 f_table[0].frequency = fsb * min_multiplier;
 273                 f_table[0].index = (min_multiplier << 8) | min_voltage;
 274                 f_table[1].frequency = fsb * max_multiplier;
 275                 f_table[1].index = (max_multiplier << 8) | max_voltage;
 276                 f_table[2].frequency = CPUFREQ_TABLE_END;
 277         } else {
 278                 k = 0;
 279                 step = ((max_voltage - min_voltage) * 256)
 280                         / (max_multiplier - min_multiplier);
 281                 for (i = min_multiplier; i <= max_multiplier; i++) {
 282                         voltage = (k * step) / 256 + min_voltage;
 283                         f_table[k].frequency = fsb * i;
 284                         f_table[k].index = (i << 8) | voltage;
 285                         k++;
 286                 }
 287                 f_table[k].frequency = CPUFREQ_TABLE_END;
 288         }
 289
 290         policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
 291         policy->cur = fsb * current_multiplier;
 292
 293         ret = cpufreq_frequency_table_cpuinfo(policy, &centaur->freq_table[0]);
 294         if (ret) {
 295                 kfree(centaur);
 296                 return ret;
 297         }
 298
 299         cpufreq_frequency_table_get_attr(&centaur->freq_table[0], policy->cpu);
 300         return 0;
 301 }
 302
 303 static int eps_cpu_exit(struct cpufreq_policy *policy)
 304 {
 305         unsigned int cpu = policy->cpu;
 306         struct eps_cpu_data *centaur;
 307         u32 lo, hi;
 308
 309         if (eps_cpu[cpu] == NULL)
 310                 return -ENODEV;
 311         centaur = eps_cpu[cpu];
 312
 313         /* Get max frequency */
 314         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 315         /* Set max frequency */
 316         eps_set_state(centaur, cpu, hi & 0xffff);
 317         /* Bye */
 318         cpufreq_frequency_table_put_attr(policy->cpu);
 319         kfree(eps_cpu[cpu]);
 320         eps_cpu[cpu] = NULL;
 321         return 0;
 322 }
 323
 324 static struct freq_attr *eps_attr[] = {
 325         &cpufreq_freq_attr_scaling_available_freqs,
 326         NULL,
 327 };
 328
 329 static struct cpufreq_driver eps_driver = {
 330         .verify         = eps_verify,
 331         .target         = eps_target,
 332         .init           = eps_cpu_init,
 333         .exit           = eps_cpu_exit,
 334         .get            = eps_get,
 335         .name           = "e_powersaver",
 336         .owner          = THIS_MODULE,
 337         .attr           = eps_attr,
 338 };
 339
 340 static int __init eps_init(void)
 341 {
 342         struct cpuinfo_x86 *c = &cpu_data(0);
 343
 344         /* This driver will work only on Centaur C7 processors with
 345          * Enhanced SpeedStep/PowerSaver registers */
 346         if (c->x86_vendor != X86_VENDOR_CENTAUR
 347             || c->x86 != 6 || c->x86_model < 10)
 348                 return -ENODEV;
 349         if (!cpu_has(c, X86_FEATURE_EST))
 350                 return -ENODEV;
 351
 352         if (cpufreq_register_driver(&eps_driver))
 353                 return -EINVAL;
 354         return 0;
 355 }
 356
 357 static void __exit eps_exit(void)
 358 {
 359         cpufreq_unregister_driver(&eps_driver);
 360 }
 361
 362 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
 363 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
 364 MODULE_LICENSE("GPL");
 365
 366 module_init(eps_init);
 367 module_exit(eps_exit);