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
  16 #include <asm/msr.h>
  17 #include <asm/tsc.h>
  18 #include <asm/timex.h>
  19 #include <asm/io.h>
  20 #include <asm/delay.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         u8 current_multiplier, current_voltage;
  59         int err = 0;
  60         int i;
  61
  62         freqs.old = eps_get(cpu);
  63         freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
  64         freqs.cpu = cpu;
  65         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  66
  67         /* Wait while CPU is busy */
  68         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  69         i = 0;
  70         while (lo & ((1 << 16) | (1 << 17))) {
  71                 udelay(16);
  72                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  73                 i++;
  74                 if (unlikely(i > 64)) {
  75                         err = -ENODEV;
  76                         goto postchange;
  77                 }
  78         }
  79         /* Set new multiplier and voltage */
  80         wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
  81         /* Wait until transition end */
  82         i = 0;
  83         do {
  84                 udelay(16);
  85                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  86                 i++;
  87                 if (unlikely(i > 64)) {
  88                         err = -ENODEV;
  89                         goto postchange;
  90                 }
  91         } while (lo & ((1 << 16) | (1 << 17)));
  92
  93         /* Return current frequency */
  94 postchange:
  95         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  96         freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
  97
  98         /* Print voltage and multiplier */
  99         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 100         current_voltage = lo & 0xff;
 101         printk(KERN_INFO "eps: Current voltage = %dmV\n",
 102                 current_voltage * 16 + 700);
 103         current_multiplier = (lo >> 8) & 0xff;
 104         printk(KERN_INFO "eps: Current multiplier = %d\n",
 105                 current_multiplier);
 106
 107         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 108         return err;
 109 }
 110
 111 static int eps_target(struct cpufreq_policy *policy,
 112                                unsigned int target_freq,
 113                                unsigned int relation)
 114 {
 115         struct eps_cpu_data *centaur;
 116         unsigned int newstate = 0;
 117         unsigned int cpu = policy->cpu;
 118         unsigned int dest_state;
 119         int ret;
 120
 121         if (unlikely(eps_cpu[cpu] == NULL))
 122                 return -ENODEV;
 123         centaur = eps_cpu[cpu];
 124
 125         if (unlikely(cpufreq_frequency_table_target(policy,
 126                         &eps_cpu[cpu]->freq_table[0],
 127                         target_freq,
 128                         relation,
 129                         &newstate))) {
 130                 return -EINVAL;
 131         }
 132
 133         /* Make frequency transition */
 134         dest_state = centaur->freq_table[newstate].index & 0xffff;
 135         ret = eps_set_state(centaur, cpu, dest_state);
 136         if (ret)
 137                 printk(KERN_ERR "eps: Timeout!\n");
 138         return ret;
 139 }
 140
 141 static int eps_verify(struct cpufreq_policy *policy)
 142 {
 143         return cpufreq_frequency_table_verify(policy,
 144                         &eps_cpu[policy->cpu]->freq_table[0]);
 145 }
 146
 147 static int eps_cpu_init(struct cpufreq_policy *policy)
 148 {
 149         unsigned int i;
 150         u32 lo, hi;
 151         u64 val;
 152         u8 current_multiplier, current_voltage;
 153         u8 max_multiplier, max_voltage;
 154         u8 min_multiplier, min_voltage;
 155         u8 brand = 0;
 156         u32 fsb;
 157         struct eps_cpu_data *centaur;
 158         struct cpuinfo_x86 *c = &cpu_data(0);
 159         struct cpufreq_frequency_table *f_table;
 160         int k, step, voltage;
 161         int ret;
 162         int states;
 163
 164         if (policy->cpu != 0)
 165                 return -ENODEV;
 166
 167         /* Check brand */
 168         printk(KERN_INFO "eps: Detected VIA ");
 169
 170         switch (c->x86_model) {
 171         case 10:
 172                 rdmsr(0x1153, lo, hi);
 173                 brand = (((lo >> 2) ^ lo) >> 18) & 3;
 174                 printk(KERN_CONT "Model A ");
 175                 break;
 176         case 13:
 177                 rdmsr(0x1154, lo, hi);
 178                 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
 179                 printk(KERN_CONT "Model D ");
 180                 break;
 181         }
 182
 183         switch(brand) {
 184         case EPS_BRAND_C7M:
 185                 printk(KERN_CONT "C7-M\n");
 186                 break;
 187         case EPS_BRAND_C7:
 188                 printk(KERN_CONT "C7\n");
 189                 break;
 190         case EPS_BRAND_EDEN:
 191                 printk(KERN_CONT "Eden\n");
 192                 break;
 193         case EPS_BRAND_C7D:
 194                 printk(KERN_CONT "C7-D\n");
 195                 break;
 196         case EPS_BRAND_C3:
 197                 printk(KERN_CONT "C3\n");
 198                 return -ENODEV;
 199                 break;
 200         }
 201         /* Enable Enhanced PowerSaver */
 202         rdmsrl(MSR_IA32_MISC_ENABLE, val);
 203         if (!(val & 1 << 16)) {
 204                 val |= 1 << 16;
 205                 wrmsrl(MSR_IA32_MISC_ENABLE, val);
 206                 /* Can be locked at 0 */
 207                 rdmsrl(MSR_IA32_MISC_ENABLE, val);
 208                 if (!(val & 1 << 16)) {
 209                         printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
 210                         return -ENODEV;
 211                 }
 212         }
 213
 214         /* Print voltage and multiplier */
 215         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 216         current_voltage = lo & 0xff;
 217         printk(KERN_INFO "eps: Current voltage = %dmV\n", current_voltage * 16 + 700);
 218         current_multiplier = (lo >> 8) & 0xff;
 219         printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
 220
 221         /* Print limits */
 222         max_voltage = hi & 0xff;
 223         printk(KERN_INFO "eps: Highest voltage = %dmV\n", max_voltage * 16 + 700);
 224         max_multiplier = (hi >> 8) & 0xff;
 225         printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
 226         min_voltage = (hi >> 16) & 0xff;
 227         printk(KERN_INFO "eps: Lowest voltage = %dmV\n", min_voltage * 16 + 700);
 228         min_multiplier = (hi >> 24) & 0xff;
 229         printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
 230
 231         /* Sanity checks */
 232         if (current_multiplier == 0 || max_multiplier == 0
 233             || min_multiplier == 0)
 234                 return -EINVAL;
 235         if (current_multiplier > max_multiplier
 236             || max_multiplier <= min_multiplier)
 237                 return -EINVAL;
 238         if (current_voltage > 0x1f || max_voltage > 0x1f)
 239                 return -EINVAL;
 240         if (max_voltage < min_voltage)
 241                 return -EINVAL;
 242
 243         /* Calc FSB speed */
 244         fsb = cpu_khz / current_multiplier;
 245         /* Calc number of p-states supported */
 246         if (brand == EPS_BRAND_C7M)
 247                 states = max_multiplier - min_multiplier + 1;
 248         else
 249                 states = 2;
 250
 251         /* Allocate private data and frequency table for current cpu */
 252         centaur = kzalloc(sizeof(struct eps_cpu_data)
 253                     + (states + 1) * sizeof(struct cpufreq_frequency_table),
 254                     GFP_KERNEL);
 255         if (!centaur)
 256                 return -ENOMEM;
 257         eps_cpu[0] = centaur;
 258
 259         /* Copy basic values */
 260         centaur->fsb = fsb;
 261
 262         /* Fill frequency and MSR value table */
 263         f_table = &centaur->freq_table[0];
 264         if (brand != EPS_BRAND_C7M) {
 265                 f_table[0].frequency = fsb * min_multiplier;
 266                 f_table[0].index = (min_multiplier << 8) | min_voltage;
 267                 f_table[1].frequency = fsb * max_multiplier;
 268                 f_table[1].index = (max_multiplier << 8) | max_voltage;
 269                 f_table[2].frequency = CPUFREQ_TABLE_END;
 270         } else {
 271                 k = 0;
 272                 step = ((max_voltage - min_voltage) * 256)
 273                         / (max_multiplier - min_multiplier);
 274                 for (i = min_multiplier; i <= max_multiplier; i++) {
 275                         voltage = (k * step) / 256 + min_voltage;
 276                         f_table[k].frequency = fsb * i;
 277                         f_table[k].index = (i << 8) | voltage;
 278                         k++;
 279                 }
 280                 f_table[k].frequency = CPUFREQ_TABLE_END;
 281         }
 282
 283         policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
 284         policy->cur = fsb * current_multiplier;
 285
 286         ret = cpufreq_frequency_table_cpuinfo(policy, &centaur->freq_table[0]);
 287         if (ret) {
 288                 kfree(centaur);
 289                 return ret;
 290         }
 291
 292         cpufreq_frequency_table_get_attr(&centaur->freq_table[0], policy->cpu);
 293         return 0;
 294 }
 295
 296 static int eps_cpu_exit(struct cpufreq_policy *policy)
 297 {
 298         unsigned int cpu = policy->cpu;
 299         struct eps_cpu_data *centaur;
 300         u32 lo, hi;
 301
 302         if (eps_cpu[cpu] == NULL)
 303                 return -ENODEV;
 304         centaur = eps_cpu[cpu];
 305
 306         /* Get max frequency */
 307         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 308         /* Set max frequency */
 309         eps_set_state(centaur, cpu, hi & 0xffff);
 310         /* Bye */
 311         cpufreq_frequency_table_put_attr(policy->cpu);
 312         kfree(eps_cpu[cpu]);
 313         eps_cpu[cpu] = NULL;
 314         return 0;
 315 }
 316
 317 static struct freq_attr* eps_attr[] = {
 318         &cpufreq_freq_attr_scaling_available_freqs,
 319         NULL,
 320 };
 321
 322 static struct cpufreq_driver eps_driver = {
 323         .verify         = eps_verify,
 324         .target         = eps_target,
 325         .init           = eps_cpu_init,
 326         .exit           = eps_cpu_exit,
 327         .get            = eps_get,
 328         .name           = "e_powersaver",
 329         .owner          = THIS_MODULE,
 330         .attr           = eps_attr,
 331 };
 332
 333 static int __init eps_init(void)
 334 {
 335         struct cpuinfo_x86 *c = &cpu_data(0);
 336
 337         /* This driver will work only on Centaur C7 processors with
 338          * Enhanced SpeedStep/PowerSaver registers */
 339         if (c->x86_vendor != X86_VENDOR_CENTAUR
 340             || c->x86 != 6 || c->x86_model < 10)
 341                 return -ENODEV;
 342         if (!cpu_has(c, X86_FEATURE_EST))
 343                 return -ENODEV;
 344
 345         if (cpufreq_register_driver(&eps_driver))
 346                 return -EINVAL;
 347         return 0;
 348 }
 349
 350 static void __exit eps_exit(void)
 351 {
 352         cpufreq_unregister_driver(&eps_driver);
 353 }
 354
 355 MODULE_AUTHOR("Rafa³ Bilski <rafalbilski@interia.pl>");
 356 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
 357 MODULE_LICENSE("GPL");
 358
 359 module_init(eps_init);
 360 module_exit(eps_exit);