1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de> 4 * 5 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous* 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/cpufreq.h> 12 #include <linux/timex.h> 13 14 #include <asm/msr.h> 15 #include <asm/processor.h> 16 #include <asm/cpu_device_id.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 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_cpu_limits(policy); 132 133 if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) && 134 (policy->policy != CPUFREQ_POLICY_PERFORMANCE)) 135 return -EINVAL; 136 137 return 0; 138 } 139 140 static unsigned int longrun_get(unsigned int cpu) 141 { 142 u32 eax, ebx, ecx, edx; 143 144 if (cpu) 145 return 0; 146 147 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 148 pr_debug("cpuid eax is %u\n", eax); 149 150 return eax * 1000; 151 } 152 153 /** 154 * longrun_determine_freqs - determines the lowest and highest possible core frequency 155 * @low_freq: an int to put the lowest frequency into 156 * @high_freq: an int to put the highest frequency into 157 * 158 * Determines the lowest and highest possible core frequencies on this CPU. 159 * This is necessary to calculate the performance percentage according to 160 * TMTA rules: 161 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 162 */ 163 static int longrun_determine_freqs(unsigned int *low_freq, 164 unsigned int *high_freq) 165 { 166 u32 msr_lo, msr_hi; 167 u32 save_lo, save_hi; 168 u32 eax, ebx, ecx, edx; 169 u32 try_hi; 170 struct cpuinfo_x86 *c = &cpu_data(0); 171 172 if (!low_freq || !high_freq) 173 return -EINVAL; 174 175 if (cpu_has(c, X86_FEATURE_LRTI)) { 176 /* if the LongRun Table Interface is present, the 177 * detection is a bit easier: 178 * For minimum frequency, read out the maximum 179 * level (msr_hi), write that into "currently 180 * selected level", and read out the frequency. 181 * For maximum frequency, read out level zero. 182 */ 183 /* minimum */ 184 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 185 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 186 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 187 *low_freq = msr_lo * 1000; /* to kHz */ 188 189 /* maximum */ 190 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 191 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 192 *high_freq = msr_lo * 1000; /* to kHz */ 193 194 pr_debug("longrun table interface told %u - %u kHz\n", 195 *low_freq, *high_freq); 196 197 if (*low_freq > *high_freq) 198 *low_freq = *high_freq; 199 return 0; 200 } 201 202 /* set the upper border to the value determined during TSC init */ 203 *high_freq = (cpu_khz / 1000); 204 *high_freq = *high_freq * 1000; 205 pr_debug("high frequency is %u kHz\n", *high_freq); 206 207 /* get current borders */ 208 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 209 save_lo = msr_lo & 0x0000007F; 210 save_hi = msr_hi & 0x0000007F; 211 212 /* if current perf_pctg is larger than 90%, we need to decrease the 213 * upper limit to make the calculation more accurate. 214 */ 215 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 216 /* try decreasing in 10% steps, some processors react only 217 * on some barrier values */ 218 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 219 /* set to 0 to try_hi perf_pctg */ 220 msr_lo &= 0xFFFFFF80; 221 msr_hi &= 0xFFFFFF80; 222 msr_hi |= try_hi; 223 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 224 225 /* read out current core MHz and current perf_pctg */ 226 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 227 228 /* restore values */ 229 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 230 } 231 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 232 233 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 234 * eqals 235 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 236 * 237 * high_freq * perf_pctg is stored tempoarily into "ebx". 238 */ 239 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 240 241 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 242 return -EIO; 243 244 edx = ((eax - ebx) * 100) / (100 - ecx); 245 *low_freq = edx * 1000; /* back to kHz */ 246 247 pr_debug("low frequency is %u kHz\n", *low_freq); 248 249 if (*low_freq > *high_freq) 250 *low_freq = *high_freq; 251 252 return 0; 253 } 254 255 256 static int longrun_cpu_init(struct cpufreq_policy *policy) 257 { 258 int result = 0; 259 260 /* capability check */ 261 if (policy->cpu != 0) 262 return -ENODEV; 263 264 /* detect low and high frequency */ 265 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 266 if (result) 267 return result; 268 269 /* cpuinfo and default policy values */ 270 policy->cpuinfo.min_freq = longrun_low_freq; 271 policy->cpuinfo.max_freq = longrun_high_freq; 272 longrun_get_policy(policy); 273 274 return 0; 275 } 276 277 278 static struct cpufreq_driver longrun_driver = { 279 .flags = CPUFREQ_CONST_LOOPS, 280 .verify = longrun_verify_policy, 281 .setpolicy = longrun_set_policy, 282 .get = longrun_get, 283 .init = longrun_cpu_init, 284 .name = "longrun", 285 }; 286 287 static const struct x86_cpu_id longrun_ids[] = { 288 { X86_VENDOR_TRANSMETA, X86_FAMILY_ANY, X86_MODEL_ANY, 289 X86_FEATURE_LONGRUN }, 290 {} 291 }; 292 MODULE_DEVICE_TABLE(x86cpu, longrun_ids); 293 294 /** 295 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 296 * 297 * Initializes the LongRun support. 298 */ 299 static int __init longrun_init(void) 300 { 301 if (!x86_match_cpu(longrun_ids)) 302 return -ENODEV; 303 return cpufreq_register_driver(&longrun_driver); 304 } 305 306 307 /** 308 * longrun_exit - unregisters LongRun support 309 */ 310 static void __exit longrun_exit(void) 311 { 312 cpufreq_unregister_driver(&longrun_driver); 313 } 314 315 316 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 317 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 318 "Efficeon processors."); 319 MODULE_LICENSE("GPL"); 320 321 module_init(longrun_init); 322 module_exit(longrun_exit); 323