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 18 static struct cpufreq_driver longrun_driver; 19 20 /** 21 * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz 22 * values into per cent values. In TMTA microcode, the following is valid: 23 * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 24 */ 25 static unsigned int longrun_low_freq, longrun_high_freq; 26 27 28 /** 29 * longrun_get_policy - get the current LongRun policy 30 * @policy: struct cpufreq_policy where current policy is written into 31 * 32 * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS 33 * and MSR_TMTA_LONGRUN_CTRL 34 */ 35 static void __cpuinit longrun_get_policy(struct cpufreq_policy *policy) 36 { 37 u32 msr_lo, msr_hi; 38 39 rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 40 pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi); 41 if (msr_lo & 0x01) 42 policy->policy = CPUFREQ_POLICY_PERFORMANCE; 43 else 44 policy->policy = CPUFREQ_POLICY_POWERSAVE; 45 46 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 47 pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi); 48 msr_lo &= 0x0000007F; 49 msr_hi &= 0x0000007F; 50 51 if (longrun_high_freq <= longrun_low_freq) { 52 /* Assume degenerate Longrun table */ 53 policy->min = policy->max = longrun_high_freq; 54 } else { 55 policy->min = longrun_low_freq + msr_lo * 56 ((longrun_high_freq - longrun_low_freq) / 100); 57 policy->max = longrun_low_freq + msr_hi * 58 ((longrun_high_freq - longrun_low_freq) / 100); 59 } 60 policy->cpu = 0; 61 } 62 63 64 /** 65 * longrun_set_policy - sets a new CPUFreq policy 66 * @policy: new policy 67 * 68 * Sets a new CPUFreq policy on LongRun-capable processors. This function 69 * has to be called with cpufreq_driver locked. 70 */ 71 static int longrun_set_policy(struct cpufreq_policy *policy) 72 { 73 u32 msr_lo, msr_hi; 74 u32 pctg_lo, pctg_hi; 75 76 if (!policy) 77 return -EINVAL; 78 79 if (longrun_high_freq <= longrun_low_freq) { 80 /* Assume degenerate Longrun table */ 81 pctg_lo = pctg_hi = 100; 82 } else { 83 pctg_lo = (policy->min - longrun_low_freq) / 84 ((longrun_high_freq - longrun_low_freq) / 100); 85 pctg_hi = (policy->max - longrun_low_freq) / 86 ((longrun_high_freq - longrun_low_freq) / 100); 87 } 88 89 if (pctg_hi > 100) 90 pctg_hi = 100; 91 if (pctg_lo > pctg_hi) 92 pctg_lo = pctg_hi; 93 94 /* performance or economy mode */ 95 rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 96 msr_lo &= 0xFFFFFFFE; 97 switch (policy->policy) { 98 case CPUFREQ_POLICY_PERFORMANCE: 99 msr_lo |= 0x00000001; 100 break; 101 case CPUFREQ_POLICY_POWERSAVE: 102 break; 103 } 104 wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 105 106 /* lower and upper boundary */ 107 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 108 msr_lo &= 0xFFFFFF80; 109 msr_hi &= 0xFFFFFF80; 110 msr_lo |= pctg_lo; 111 msr_hi |= pctg_hi; 112 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 113 114 return 0; 115 } 116 117 118 /** 119 * longrun_verify_poliy - verifies a new CPUFreq policy 120 * @policy: the policy to verify 121 * 122 * Validates a new CPUFreq policy. This function has to be called with 123 * cpufreq_driver locked. 124 */ 125 static int longrun_verify_policy(struct cpufreq_policy *policy) 126 { 127 if (!policy) 128 return -EINVAL; 129 130 policy->cpu = 0; 131 cpufreq_verify_within_limits(policy, 132 policy->cpuinfo.min_freq, 133 policy->cpuinfo.max_freq); 134 135 if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) && 136 (policy->policy != CPUFREQ_POLICY_PERFORMANCE)) 137 return -EINVAL; 138 139 return 0; 140 } 141 142 static unsigned int longrun_get(unsigned int cpu) 143 { 144 u32 eax, ebx, ecx, edx; 145 146 if (cpu) 147 return 0; 148 149 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 150 pr_debug("cpuid eax is %u\n", eax); 151 152 return eax * 1000; 153 } 154 155 /** 156 * longrun_determine_freqs - determines the lowest and highest possible core frequency 157 * @low_freq: an int to put the lowest frequency into 158 * @high_freq: an int to put the highest frequency into 159 * 160 * Determines the lowest and highest possible core frequencies on this CPU. 161 * This is necessary to calculate the performance percentage according to 162 * TMTA rules: 163 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 164 */ 165 static int __cpuinit longrun_determine_freqs(unsigned int *low_freq, 166 unsigned int *high_freq) 167 { 168 u32 msr_lo, msr_hi; 169 u32 save_lo, save_hi; 170 u32 eax, ebx, ecx, edx; 171 u32 try_hi; 172 struct cpuinfo_x86 *c = &cpu_data(0); 173 174 if (!low_freq || !high_freq) 175 return -EINVAL; 176 177 if (cpu_has(c, X86_FEATURE_LRTI)) { 178 /* if the LongRun Table Interface is present, the 179 * detection is a bit easier: 180 * For minimum frequency, read out the maximum 181 * level (msr_hi), write that into "currently 182 * selected level", and read out the frequency. 183 * For maximum frequency, read out level zero. 184 */ 185 /* minimum */ 186 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 187 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 188 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 189 *low_freq = msr_lo * 1000; /* to kHz */ 190 191 /* maximum */ 192 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 193 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 194 *high_freq = msr_lo * 1000; /* to kHz */ 195 196 pr_debug("longrun table interface told %u - %u kHz\n", 197 *low_freq, *high_freq); 198 199 if (*low_freq > *high_freq) 200 *low_freq = *high_freq; 201 return 0; 202 } 203 204 /* set the upper border to the value determined during TSC init */ 205 *high_freq = (cpu_khz / 1000); 206 *high_freq = *high_freq * 1000; 207 pr_debug("high frequency is %u kHz\n", *high_freq); 208 209 /* get current borders */ 210 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 211 save_lo = msr_lo & 0x0000007F; 212 save_hi = msr_hi & 0x0000007F; 213 214 /* if current perf_pctg is larger than 90%, we need to decrease the 215 * upper limit to make the calculation more accurate. 216 */ 217 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 218 /* try decreasing in 10% steps, some processors react only 219 * on some barrier values */ 220 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 221 /* set to 0 to try_hi perf_pctg */ 222 msr_lo &= 0xFFFFFF80; 223 msr_hi &= 0xFFFFFF80; 224 msr_hi |= try_hi; 225 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 226 227 /* read out current core MHz and current perf_pctg */ 228 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 229 230 /* restore values */ 231 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 232 } 233 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 234 235 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 236 * eqals 237 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 238 * 239 * high_freq * perf_pctg is stored tempoarily into "ebx". 240 */ 241 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 242 243 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 244 return -EIO; 245 246 edx = ((eax - ebx) * 100) / (100 - ecx); 247 *low_freq = edx * 1000; /* back to kHz */ 248 249 pr_debug("low frequency is %u kHz\n", *low_freq); 250 251 if (*low_freq > *high_freq) 252 *low_freq = *high_freq; 253 254 return 0; 255 } 256 257 258 static int __cpuinit longrun_cpu_init(struct cpufreq_policy *policy) 259 { 260 int result = 0; 261 262 /* capability check */ 263 if (policy->cpu != 0) 264 return -ENODEV; 265 266 /* detect low and high frequency */ 267 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 268 if (result) 269 return result; 270 271 /* cpuinfo and default policy values */ 272 policy->cpuinfo.min_freq = longrun_low_freq; 273 policy->cpuinfo.max_freq = longrun_high_freq; 274 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 275 longrun_get_policy(policy); 276 277 return 0; 278 } 279 280 281 static struct cpufreq_driver longrun_driver = { 282 .flags = CPUFREQ_CONST_LOOPS, 283 .verify = longrun_verify_policy, 284 .setpolicy = longrun_set_policy, 285 .get = longrun_get, 286 .init = longrun_cpu_init, 287 .name = "longrun", 288 .owner = THIS_MODULE, 289 }; 290 291 292 /** 293 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 294 * 295 * Initializes the LongRun support. 296 */ 297 static int __init longrun_init(void) 298 { 299 struct cpuinfo_x86 *c = &cpu_data(0); 300 301 if (c->x86_vendor != X86_VENDOR_TRANSMETA || 302 !cpu_has(c, X86_FEATURE_LONGRUN)) 303 return -ENODEV; 304 305 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