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
  27 struct eps_cpu_data {
  28         u32 fsb;
  29         struct cpufreq_frequency_table freq_table[];
  30 };
  31
  32 static struct eps_cpu_data *eps_cpu[NR_CPUS];
  33
  34
  35 static unsigned int eps_get(unsigned int cpu)
  36 {
  37         struct eps_cpu_data *centaur;
  38         u32 lo, hi;
  39
  40         if (cpu)
  41                 return 0;
  42         centaur = eps_cpu[cpu];
  43         if (centaur == NULL)
  44                 return 0;
  45
  46         /* Return current frequency */
  47         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  48         return centaur->fsb * ((lo >> 8) & 0xff);
  49 }
  50
  51 static int eps_set_state(struct eps_cpu_data *centaur,
  52                          unsigned int cpu,
  53                          u32 dest_state)
  54 {
  55         struct cpufreq_freqs freqs;
  56         u32 lo, hi;
  57         int err = 0;
  58         int i;
  59
  60         freqs.old = eps_get(cpu);
  61         freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
  62         freqs.cpu = cpu;
  63         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  64
  65         /* Wait while CPU is busy */
  66         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  67         i = 0;
  68         while (lo & ((1 << 16) | (1 << 17))) {
  69                 udelay(16);
  70                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  71                 i++;
  72                 if (unlikely(i > 64)) {
  73                         err = -ENODEV;
  74                         goto postchange;
  75                 }
  76         }
  77         /* Set new multiplier and voltage */
  78         wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
  79         /* Wait until transition end */
  80         i = 0;
  81         do {
  82                 udelay(16);
  83                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  84                 i++;
  85                 if (unlikely(i > 64)) {
  86                         err = -ENODEV;
  87                         goto postchange;
  88                 }
  89         } while (lo & ((1 << 16) | (1 << 17)));
  90
  91         /* Return current frequency */
  92 postchange:
  93         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  94         freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
  95
  96         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  97         return err;
  98 }
  99
 100 static int eps_target(struct cpufreq_policy *policy,
 101                                unsigned int target_freq,
 102                                unsigned int relation)
 103 {
 104         struct eps_cpu_data *centaur;
 105         unsigned int newstate = 0;
 106         unsigned int cpu = policy->cpu;
 107         unsigned int dest_state;
 108         int ret;
 109
 110         if (unlikely(eps_cpu[cpu] == NULL))
 111                 return -ENODEV;
 112         centaur = eps_cpu[cpu];
 113
 114         if (unlikely(cpufreq_frequency_table_target(policy,
 115                         &eps_cpu[cpu]->freq_table[0],
 116                         target_freq,
 117                         relation,
 118                         &newstate))) {
 119                 return -EINVAL;
 120         }
 121
 122         /* Make frequency transition */
 123         dest_state = centaur->freq_table[newstate].index & 0xffff;
 124         ret = eps_set_state(centaur, cpu, dest_state);
 125         if (ret)
 126                 printk(KERN_ERR "eps: Timeout!\n");
 127         return ret;
 128 }
 129
 130 static int eps_verify(struct cpufreq_policy *policy)
 131 {
 132         return cpufreq_frequency_table_verify(policy,
 133                         &eps_cpu[policy->cpu]->freq_table[0]);
 134 }
 135
 136 static int eps_cpu_init(struct cpufreq_policy *policy)
 137 {
 138         unsigned int i;
 139         u32 lo, hi;
 140         u64 val;
 141         u8 current_multiplier, current_voltage;
 142         u8 max_multiplier, max_voltage;
 143         u8 min_multiplier, min_voltage;
 144         u8 brand;
 145         u32 fsb;
 146         struct eps_cpu_data *centaur;
 147         struct cpufreq_frequency_table *f_table;
 148         int k, step, voltage;
 149         int ret;
 150         int states;
 151
 152         if (policy->cpu != 0)
 153                 return -ENODEV;
 154
 155         /* Check brand */
 156         printk("eps: Detected VIA ");
 157         rdmsr(0x1153, lo, hi);
 158         brand = (((lo >> 2) ^ lo) >> 18) & 3;
 159         switch(brand) {
 160         case EPS_BRAND_C7M:
 161                 printk("C7-M\n");
 162                 break;
 163         case EPS_BRAND_C7:
 164                 printk("C7\n");
 165                 break;
 166         case EPS_BRAND_EDEN:
 167                 printk("Eden\n");
 168                 break;
 169         case EPS_BRAND_C3:
 170                 printk("C3\n");
 171                 return -ENODEV;
 172                 break;
 173         }
 174         /* Enable Enhanced PowerSaver */
 175         rdmsrl(MSR_IA32_MISC_ENABLE, val);
 176         if (!(val & 1 << 16)) {
 177                 val |= 1 << 16;
 178                 wrmsrl(MSR_IA32_MISC_ENABLE, val);
 179                 /* Can be locked at 0 */
 180                 rdmsrl(MSR_IA32_MISC_ENABLE, val);
 181                 if (!(val & 1 << 16)) {
 182                         printk("eps: Can't enable Enhanced PowerSaver\n");
 183                         return -ENODEV;
 184                 }
 185         }
 186
 187         /* Print voltage and multiplier */
 188         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 189         current_voltage = lo & 0xff;
 190         printk("eps: Current voltage = %dmV\n", current_voltage * 16 + 700);
 191         current_multiplier = (lo >> 8) & 0xff;
 192         printk("eps: Current multiplier = %d\n", current_multiplier);
 193
 194         /* Print limits */
 195         max_voltage = hi & 0xff;
 196         printk("eps: Highest voltage = %dmV\n", max_voltage * 16 + 700);
 197         max_multiplier = (hi >> 8) & 0xff;
 198         printk("eps: Highest multiplier = %d\n", max_multiplier);
 199         min_voltage = (hi >> 16) & 0xff;
 200         printk("eps: Lowest voltage = %dmV\n", min_voltage * 16 + 700);
 201         min_multiplier = (hi >> 24) & 0xff;
 202         printk("eps: Lowest multiplier = %d\n", min_multiplier);
 203
 204         /* Sanity checks */
 205         if (current_multiplier == 0 || max_multiplier == 0
 206             || min_multiplier == 0)
 207                 return -EINVAL;
 208         if (current_multiplier > max_multiplier
 209             || max_multiplier <= min_multiplier)
 210                 return -EINVAL;
 211         if (current_voltage > 0x1c || max_voltage > 0x1c)
 212                 return -EINVAL;
 213         if (max_voltage < min_voltage)
 214                 return -EINVAL;
 215
 216         /* Calc FSB speed */
 217         fsb = cpu_khz / current_multiplier;
 218         /* Calc number of p-states supported */
 219         if (brand == EPS_BRAND_C7M)
 220                 states = max_multiplier - min_multiplier + 1;
 221         else
 222                 states = 2;
 223
 224         /* Allocate private data and frequency table for current cpu */
 225         centaur = kzalloc(sizeof(struct eps_cpu_data)
 226                     + (states + 1) * sizeof(struct cpufreq_frequency_table),
 227                     GFP_KERNEL);
 228         if (!centaur)
 229                 return -ENOMEM;
 230         eps_cpu[0] = centaur;
 231
 232         /* Copy basic values */
 233         centaur->fsb = fsb;
 234
 235         /* Fill frequency and MSR value table */
 236         f_table = &centaur->freq_table[0];
 237         if (brand != EPS_BRAND_C7M) {
 238                 f_table[0].frequency = fsb * min_multiplier;
 239                 f_table[0].index = (min_multiplier << 8) | min_voltage;
 240                 f_table[1].frequency = fsb * max_multiplier;
 241                 f_table[1].index = (max_multiplier << 8) | max_voltage;
 242                 f_table[2].frequency = CPUFREQ_TABLE_END;
 243         } else {
 244                 k = 0;
 245                 step = ((max_voltage - min_voltage) * 256)
 246                         / (max_multiplier - min_multiplier);
 247                 for (i = min_multiplier; i <= max_multiplier; i++) {
 248                         voltage = (k * step) / 256 + min_voltage;
 249                         f_table[k].frequency = fsb * i;
 250                         f_table[k].index = (i << 8) | voltage;
 251                         k++;
 252                 }
 253                 f_table[k].frequency = CPUFREQ_TABLE_END;
 254         }
 255
 256         policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
 257         policy->cur = fsb * current_multiplier;
 258
 259         ret = cpufreq_frequency_table_cpuinfo(policy, &centaur->freq_table[0]);
 260         if (ret) {
 261                 kfree(centaur);
 262                 return ret;
 263         }
 264
 265         cpufreq_frequency_table_get_attr(&centaur->freq_table[0], policy->cpu);
 266         return 0;
 267 }
 268
 269 static int eps_cpu_exit(struct cpufreq_policy *policy)
 270 {
 271         unsigned int cpu = policy->cpu;
 272         struct eps_cpu_data *centaur;
 273         u32 lo, hi;
 274
 275         if (eps_cpu[cpu] == NULL)
 276                 return -ENODEV;
 277         centaur = eps_cpu[cpu];
 278
 279         /* Get max frequency */
 280         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 281         /* Set max frequency */
 282         eps_set_state(centaur, cpu, hi & 0xffff);
 283         /* Bye */
 284         cpufreq_frequency_table_put_attr(policy->cpu);
 285         kfree(eps_cpu[cpu]);
 286         eps_cpu[cpu] = NULL;
 287         return 0;
 288 }
 289
 290 static struct freq_attr* eps_attr[] = {
 291         &cpufreq_freq_attr_scaling_available_freqs,
 292         NULL,
 293 };
 294
 295 static struct cpufreq_driver eps_driver = {
 296         .verify         = eps_verify,
 297         .target         = eps_target,
 298         .init           = eps_cpu_init,
 299         .exit           = eps_cpu_exit,
 300         .get            = eps_get,
 301         .name           = "e_powersaver",
 302         .owner          = THIS_MODULE,
 303         .attr           = eps_attr,
 304 };
 305
 306 static int __init eps_init(void)
 307 {
 308         struct cpuinfo_x86 *c = cpu_data;
 309
 310         /* This driver will work only on Centaur C7 processors with
 311          * Enhanced SpeedStep/PowerSaver registers */
 312         if (c->x86_vendor != X86_VENDOR_CENTAUR
 313             || c->x86 != 6 || c->x86_model != 10)
 314                 return -ENODEV;
 315         if (!cpu_has(c, X86_FEATURE_EST))
 316                 return -ENODEV;
 317
 318         if (cpufreq_register_driver(&eps_driver))
 319                 return -EINVAL;
 320         return 0;
 321 }
 322
 323 static void __exit eps_exit(void)
 324 {
 325         cpufreq_unregister_driver(&eps_driver);
 326 }
 327
 328 MODULE_AUTHOR("Rafa³ Bilski <rafalbilski@interia.pl>");
 329 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
 330 MODULE_LICENSE("GPL");
 331
 332 module_init(eps_init);
 333 module_exit(eps_exit);