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 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_cpu_limits(policy); 133 134 if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) && 135 (policy->policy != CPUFREQ_POLICY_PERFORMANCE)) 136 return -EINVAL; 137 138 return 0; 139 } 140 141 static unsigned int longrun_get(unsigned int cpu) 142 { 143 u32 eax, ebx, ecx, edx; 144 145 if (cpu) 146 return 0; 147 148 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 149 pr_debug("cpuid eax is %u\n", eax); 150 151 return eax * 1000; 152 } 153 154 /** 155 * longrun_determine_freqs - determines the lowest and highest possible core frequency 156 * @low_freq: an int to put the lowest frequency into 157 * @high_freq: an int to put the highest frequency into 158 * 159 * Determines the lowest and highest possible core frequencies on this CPU. 160 * This is necessary to calculate the performance percentage according to 161 * TMTA rules: 162 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 163 */ 164 static int longrun_determine_freqs(unsigned int *low_freq, 165 unsigned int *high_freq) 166 { 167 u32 msr_lo, msr_hi; 168 u32 save_lo, save_hi; 169 u32 eax, ebx, ecx, edx; 170 u32 try_hi; 171 struct cpuinfo_x86 *c = &cpu_data(0); 172 173 if (!low_freq || !high_freq) 174 return -EINVAL; 175 176 if (cpu_has(c, X86_FEATURE_LRTI)) { 177 /* if the LongRun Table Interface is present, the 178 * detection is a bit easier: 179 * For minimum frequency, read out the maximum 180 * level (msr_hi), write that into "currently 181 * selected level", and read out the frequency. 182 * For maximum frequency, read out level zero. 183 */ 184 /* minimum */ 185 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 186 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 187 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 188 *low_freq = msr_lo * 1000; /* to kHz */ 189 190 /* maximum */ 191 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 192 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 193 *high_freq = msr_lo * 1000; /* to kHz */ 194 195 pr_debug("longrun table interface told %u - %u kHz\n", 196 *low_freq, *high_freq); 197 198 if (*low_freq > *high_freq) 199 *low_freq = *high_freq; 200 return 0; 201 } 202 203 /* set the upper border to the value determined during TSC init */ 204 *high_freq = (cpu_khz / 1000); 205 *high_freq = *high_freq * 1000; 206 pr_debug("high frequency is %u kHz\n", *high_freq); 207 208 /* get current borders */ 209 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 210 save_lo = msr_lo & 0x0000007F; 211 save_hi = msr_hi & 0x0000007F; 212 213 /* if current perf_pctg is larger than 90%, we need to decrease the 214 * upper limit to make the calculation more accurate. 215 */ 216 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 217 /* try decreasing in 10% steps, some processors react only 218 * on some barrier values */ 219 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 220 /* set to 0 to try_hi perf_pctg */ 221 msr_lo &= 0xFFFFFF80; 222 msr_hi &= 0xFFFFFF80; 223 msr_hi |= try_hi; 224 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 225 226 /* read out current core MHz and current perf_pctg */ 227 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 228 229 /* restore values */ 230 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 231 } 232 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 233 234 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 235 * eqals 236 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 237 * 238 * high_freq * perf_pctg is stored tempoarily into "ebx". 239 */ 240 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 241 242 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 243 return -EIO; 244 245 edx = ((eax - ebx) * 100) / (100 - ecx); 246 *low_freq = edx * 1000; /* back to kHz */ 247 248 pr_debug("low frequency is %u kHz\n", *low_freq); 249 250 if (*low_freq > *high_freq) 251 *low_freq = *high_freq; 252 253 return 0; 254 } 255 256 257 static int longrun_cpu_init(struct cpufreq_policy *policy) 258 { 259 int result = 0; 260 261 /* capability check */ 262 if (policy->cpu != 0) 263 return -ENODEV; 264 265 /* detect low and high frequency */ 266 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 267 if (result) 268 return result; 269 270 /* cpuinfo and default policy values */ 271 policy->cpuinfo.min_freq = longrun_low_freq; 272 policy->cpuinfo.max_freq = longrun_high_freq; 273 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 274 longrun_get_policy(policy); 275 276 return 0; 277 } 278 279 280 static struct cpufreq_driver longrun_driver = { 281 .flags = CPUFREQ_CONST_LOOPS, 282 .verify = longrun_verify_policy, 283 .setpolicy = longrun_set_policy, 284 .get = longrun_get, 285 .init = longrun_cpu_init, 286 .name = "longrun", 287 }; 288 289 static const struct x86_cpu_id longrun_ids[] = { 290 { X86_VENDOR_TRANSMETA, X86_FAMILY_ANY, X86_MODEL_ANY, 291 X86_FEATURE_LONGRUN }, 292 {} 293 }; 294 MODULE_DEVICE_TABLE(x86cpu, longrun_ids); 295 296 /** 297 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 298 * 299 * Initializes the LongRun support. 300 */ 301 static int __init longrun_init(void) 302 { 303 if (!x86_match_cpu(longrun_ids)) 304 return -ENODEV; 305 return cpufreq_register_driver(&longrun_driver); 306 } 307 308 309 /** 310 * longrun_exit - unregisters LongRun support 311 */ 312 static void __exit longrun_exit(void) 313 { 314 cpufreq_unregister_driver(&longrun_driver); 315 } 316 317 318 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 319 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 320 "Efficeon processors."); 321 MODULE_LICENSE("GPL"); 322 323 module_init(longrun_init); 324 module_exit(longrun_exit); 325