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/cpufreq.h> 13 #include <linux/timex.h> 14 15 #include <asm/msr.h> 16 #include <asm/processor.h> 17 #include <asm/cpu_device_id.h> 18 19 static struct cpufreq_driver longrun_driver; 20 21 /** 22 * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz 23 * values into per cent values. In TMTA microcode, the following is valid: 24 * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 25 */ 26 static unsigned int longrun_low_freq, longrun_high_freq; 27 28 29 /** 30 * longrun_get_policy - get the current LongRun policy 31 * @policy: struct cpufreq_policy where current policy is written into 32 * 33 * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS 34 * and MSR_TMTA_LONGRUN_CTRL 35 */ 36 static void __cpuinit longrun_get_policy(struct cpufreq_policy *policy) 37 { 38 u32 msr_lo, msr_hi; 39 40 rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 41 pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi); 42 if (msr_lo & 0x01) 43 policy->policy = CPUFREQ_POLICY_PERFORMANCE; 44 else 45 policy->policy = CPUFREQ_POLICY_POWERSAVE; 46 47 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 48 pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi); 49 msr_lo &= 0x0000007F; 50 msr_hi &= 0x0000007F; 51 52 if (longrun_high_freq <= longrun_low_freq) { 53 /* Assume degenerate Longrun table */ 54 policy->min = policy->max = longrun_high_freq; 55 } else { 56 policy->min = longrun_low_freq + msr_lo * 57 ((longrun_high_freq - longrun_low_freq) / 100); 58 policy->max = longrun_low_freq + msr_hi * 59 ((longrun_high_freq - longrun_low_freq) / 100); 60 } 61 policy->cpu = 0; 62 } 63 64 65 /** 66 * longrun_set_policy - sets a new CPUFreq policy 67 * @policy: new policy 68 * 69 * Sets a new CPUFreq policy on LongRun-capable processors. This function 70 * has to be called with cpufreq_driver locked. 71 */ 72 static int longrun_set_policy(struct cpufreq_policy *policy) 73 { 74 u32 msr_lo, msr_hi; 75 u32 pctg_lo, pctg_hi; 76 77 if (!policy) 78 return -EINVAL; 79 80 if (longrun_high_freq <= longrun_low_freq) { 81 /* Assume degenerate Longrun table */ 82 pctg_lo = pctg_hi = 100; 83 } else { 84 pctg_lo = (policy->min - longrun_low_freq) / 85 ((longrun_high_freq - longrun_low_freq) / 100); 86 pctg_hi = (policy->max - longrun_low_freq) / 87 ((longrun_high_freq - longrun_low_freq) / 100); 88 } 89 90 if (pctg_hi > 100) 91 pctg_hi = 100; 92 if (pctg_lo > pctg_hi) 93 pctg_lo = pctg_hi; 94 95 /* performance or economy mode */ 96 rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 97 msr_lo &= 0xFFFFFFFE; 98 switch (policy->policy) { 99 case CPUFREQ_POLICY_PERFORMANCE: 100 msr_lo |= 0x00000001; 101 break; 102 case CPUFREQ_POLICY_POWERSAVE: 103 break; 104 } 105 wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 106 107 /* lower and upper boundary */ 108 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 109 msr_lo &= 0xFFFFFF80; 110 msr_hi &= 0xFFFFFF80; 111 msr_lo |= pctg_lo; 112 msr_hi |= pctg_hi; 113 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 114 115 return 0; 116 } 117 118 119 /** 120 * longrun_verify_poliy - verifies a new CPUFreq policy 121 * @policy: the policy to verify 122 * 123 * Validates a new CPUFreq policy. This function has to be called with 124 * cpufreq_driver locked. 125 */ 126 static int longrun_verify_policy(struct cpufreq_policy *policy) 127 { 128 if (!policy) 129 return -EINVAL; 130 131 policy->cpu = 0; 132 cpufreq_verify_within_limits(policy, 133 policy->cpuinfo.min_freq, 134 policy->cpuinfo.max_freq); 135 136 if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) && 137 (policy->policy != CPUFREQ_POLICY_PERFORMANCE)) 138 return -EINVAL; 139 140 return 0; 141 } 142 143 static unsigned int longrun_get(unsigned int cpu) 144 { 145 u32 eax, ebx, ecx, edx; 146 147 if (cpu) 148 return 0; 149 150 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 151 pr_debug("cpuid eax is %u\n", eax); 152 153 return eax * 1000; 154 } 155 156 /** 157 * longrun_determine_freqs - determines the lowest and highest possible core frequency 158 * @low_freq: an int to put the lowest frequency into 159 * @high_freq: an int to put the highest frequency into 160 * 161 * Determines the lowest and highest possible core frequencies on this CPU. 162 * This is necessary to calculate the performance percentage according to 163 * TMTA rules: 164 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 165 */ 166 static int __cpuinit longrun_determine_freqs(unsigned int *low_freq, 167 unsigned int *high_freq) 168 { 169 u32 msr_lo, msr_hi; 170 u32 save_lo, save_hi; 171 u32 eax, ebx, ecx, edx; 172 u32 try_hi; 173 struct cpuinfo_x86 *c = &cpu_data(0); 174 175 if (!low_freq || !high_freq) 176 return -EINVAL; 177 178 if (cpu_has(c, X86_FEATURE_LRTI)) { 179 /* if the LongRun Table Interface is present, the 180 * detection is a bit easier: 181 * For minimum frequency, read out the maximum 182 * level (msr_hi), write that into "currently 183 * selected level", and read out the frequency. 184 * For maximum frequency, read out level zero. 185 */ 186 /* minimum */ 187 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 188 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 189 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 190 *low_freq = msr_lo * 1000; /* to kHz */ 191 192 /* maximum */ 193 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 194 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 195 *high_freq = msr_lo * 1000; /* to kHz */ 196 197 pr_debug("longrun table interface told %u - %u kHz\n", 198 *low_freq, *high_freq); 199 200 if (*low_freq > *high_freq) 201 *low_freq = *high_freq; 202 return 0; 203 } 204 205 /* set the upper border to the value determined during TSC init */ 206 *high_freq = (cpu_khz / 1000); 207 *high_freq = *high_freq * 1000; 208 pr_debug("high frequency is %u kHz\n", *high_freq); 209 210 /* get current borders */ 211 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 212 save_lo = msr_lo & 0x0000007F; 213 save_hi = msr_hi & 0x0000007F; 214 215 /* if current perf_pctg is larger than 90%, we need to decrease the 216 * upper limit to make the calculation more accurate. 217 */ 218 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 219 /* try decreasing in 10% steps, some processors react only 220 * on some barrier values */ 221 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 222 /* set to 0 to try_hi perf_pctg */ 223 msr_lo &= 0xFFFFFF80; 224 msr_hi &= 0xFFFFFF80; 225 msr_hi |= try_hi; 226 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 227 228 /* read out current core MHz and current perf_pctg */ 229 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 230 231 /* restore values */ 232 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 233 } 234 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 235 236 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 237 * eqals 238 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 239 * 240 * high_freq * perf_pctg is stored tempoarily into "ebx". 241 */ 242 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 243 244 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 245 return -EIO; 246 247 edx = ((eax - ebx) * 100) / (100 - ecx); 248 *low_freq = edx * 1000; /* back to kHz */ 249 250 pr_debug("low frequency is %u kHz\n", *low_freq); 251 252 if (*low_freq > *high_freq) 253 *low_freq = *high_freq; 254 255 return 0; 256 } 257 258 259 static int __cpuinit longrun_cpu_init(struct cpufreq_policy *policy) 260 { 261 int result = 0; 262 263 /* capability check */ 264 if (policy->cpu != 0) 265 return -ENODEV; 266 267 /* detect low and high frequency */ 268 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 269 if (result) 270 return result; 271 272 /* cpuinfo and default policy values */ 273 policy->cpuinfo.min_freq = longrun_low_freq; 274 policy->cpuinfo.max_freq = longrun_high_freq; 275 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 276 longrun_get_policy(policy); 277 278 return 0; 279 } 280 281 282 static struct cpufreq_driver longrun_driver = { 283 .flags = CPUFREQ_CONST_LOOPS, 284 .verify = longrun_verify_policy, 285 .setpolicy = longrun_set_policy, 286 .get = longrun_get, 287 .init = longrun_cpu_init, 288 .name = "longrun", 289 .owner = THIS_MODULE, 290 }; 291 292 static const struct x86_cpu_id longrun_ids[] = { 293 { X86_VENDOR_TRANSMETA, X86_FAMILY_ANY, X86_MODEL_ANY, 294 X86_FEATURE_LONGRUN }, 295 {} 296 }; 297 MODULE_DEVICE_TABLE(x86cpu, longrun_ids); 298 299 /** 300 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 301 * 302 * Initializes the LongRun support. 303 */ 304 static int __init longrun_init(void) 305 { 306 if (!x86_match_cpu(longrun_ids)) 307 return -ENODEV; 308 return cpufreq_register_driver(&longrun_driver); 309 } 310 311 312 /** 313 * longrun_exit - unregisters LongRun support 314 */ 315 static void __exit longrun_exit(void) 316 { 317 cpufreq_unregister_driver(&longrun_driver); 318 } 319 320 321 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 322 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 323 "Efficeon processors."); 324 MODULE_LICENSE("GPL"); 325 326 module_init(longrun_init); 327 module_exit(longrun_exit); 328