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 27struct eps_cpu_data { 28 u32 fsb; 29 struct cpufreq_frequency_table freq_table[]; 30}; 31 32static struct eps_cpu_data *eps_cpu[NR_CPUS]; 33 34 35static 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 51static 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 */ 92postchange: 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 100static 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 130static 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 136static 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 = ¢aur->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->governor = CPUFREQ_DEFAULT_GOVERNOR; 257 policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */ 258 policy->cur = fsb * current_multiplier; 259 260 ret = cpufreq_frequency_table_cpuinfo(policy, ¢aur->freq_table[0]); 261 if (ret) { 262 kfree(centaur); 263 return ret; 264 } 265 266 cpufreq_frequency_table_get_attr(¢aur->freq_table[0], policy->cpu); 267 return 0; 268} 269 270static int eps_cpu_exit(struct cpufreq_policy *policy) 271{ 272 unsigned int cpu = policy->cpu; 273 struct eps_cpu_data *centaur; 274 u32 lo, hi; 275 276 if (eps_cpu[cpu] == NULL) 277 return -ENODEV; 278 centaur = eps_cpu[cpu]; 279 280 /* Get max frequency */ 281 rdmsr(MSR_IA32_PERF_STATUS, lo, hi); 282 /* Set max frequency */ 283 eps_set_state(centaur, cpu, hi & 0xffff); 284 /* Bye */ 285 cpufreq_frequency_table_put_attr(policy->cpu); 286 kfree(eps_cpu[cpu]); 287 eps_cpu[cpu] = NULL; 288 return 0; 289} 290 291static struct freq_attr* eps_attr[] = { 292 &cpufreq_freq_attr_scaling_available_freqs, 293 NULL, 294}; 295 296static struct cpufreq_driver eps_driver = { 297 .verify = eps_verify, 298 .target = eps_target, 299 .init = eps_cpu_init, 300 .exit = eps_cpu_exit, 301 .get = eps_get, 302 .name = "e_powersaver", 303 .owner = THIS_MODULE, 304 .attr = eps_attr, 305}; 306 307static int __init eps_init(void) 308{ 309 struct cpuinfo_x86 *c = cpu_data; 310 311 /* This driver will work only on Centaur C7 processors with 312 * Enhanced SpeedStep/PowerSaver registers */ 313 if (c->x86_vendor != X86_VENDOR_CENTAUR 314 || c->x86 != 6 || c->x86_model != 10) 315 return -ENODEV; 316 if (!cpu_has(c, X86_FEATURE_EST)) 317 return -ENODEV; 318 319 if (cpufreq_register_driver(&eps_driver)) 320 return -EINVAL; 321 return 0; 322} 323 324static void __exit eps_exit(void) 325{ 326 cpufreq_unregister_driver(&eps_driver); 327} 328 329MODULE_AUTHOR("Rafa� Bilski <rafalbilski@interia.pl>"); 330MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's."); 331MODULE_LICENSE("GPL"); 332 333module_init(eps_init); 334module_exit(eps_exit); 335