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 #include <asm/cpuid/api.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_data *policy) 127 { 128 if (!policy) 129 return -EINVAL; 130 131 policy->cpu = 0; 132 cpufreq_verify_within_cpu_limits(policy); 133 134 return 0; 135 } 136 137 static unsigned int longrun_get(unsigned int cpu) 138 { 139 u32 eax, ebx, ecx, edx; 140 141 if (cpu) 142 return 0; 143 144 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 145 pr_debug("cpuid eax is %u\n", eax); 146 147 return eax * 1000; 148 } 149 150 /** 151 * longrun_determine_freqs - determines the lowest and highest possible core frequency 152 * @low_freq: an int to put the lowest frequency into 153 * @high_freq: an int to put the highest frequency into 154 * 155 * Determines the lowest and highest possible core frequencies on this CPU. 156 * This is necessary to calculate the performance percentage according to 157 * TMTA rules: 158 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 159 */ 160 static int longrun_determine_freqs(unsigned int *low_freq, 161 unsigned int *high_freq) 162 { 163 u32 msr_lo, msr_hi; 164 u32 save_lo, save_hi; 165 u32 eax, ebx, ecx, edx; 166 u32 try_hi; 167 struct cpuinfo_x86 *c = &cpu_data(0); 168 169 if (!low_freq || !high_freq) 170 return -EINVAL; 171 172 if (cpu_has(c, X86_FEATURE_LRTI)) { 173 /* if the LongRun Table Interface is present, the 174 * detection is a bit easier: 175 * For minimum frequency, read out the maximum 176 * level (msr_hi), write that into "currently 177 * selected level", and read out the frequency. 178 * For maximum frequency, read out level zero. 179 */ 180 /* minimum */ 181 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 182 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 183 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 184 *low_freq = msr_lo * 1000; /* to kHz */ 185 186 /* maximum */ 187 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 188 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 189 *high_freq = msr_lo * 1000; /* to kHz */ 190 191 pr_debug("longrun table interface told %u - %u kHz\n", 192 *low_freq, *high_freq); 193 194 if (*low_freq > *high_freq) 195 *low_freq = *high_freq; 196 return 0; 197 } 198 199 /* set the upper border to the value determined during TSC init */ 200 *high_freq = (cpu_khz / 1000); 201 *high_freq = *high_freq * 1000; 202 pr_debug("high frequency is %u kHz\n", *high_freq); 203 204 /* get current borders */ 205 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 206 save_lo = msr_lo & 0x0000007F; 207 save_hi = msr_hi & 0x0000007F; 208 209 /* if current perf_pctg is larger than 90%, we need to decrease the 210 * upper limit to make the calculation more accurate. 211 */ 212 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 213 /* try decreasing in 10% steps, some processors react only 214 * on some barrier values */ 215 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 216 /* set to 0 to try_hi perf_pctg */ 217 msr_lo &= 0xFFFFFF80; 218 msr_hi &= 0xFFFFFF80; 219 msr_hi |= try_hi; 220 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 221 222 /* read out current core MHz and current perf_pctg */ 223 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 224 225 /* restore values */ 226 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 227 } 228 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 229 230 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 231 * eqals 232 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 233 * 234 * high_freq * perf_pctg is stored tempoarily into "ebx". 235 */ 236 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 237 238 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 239 return -EIO; 240 241 edx = ((eax - ebx) * 100) / (100 - ecx); 242 *low_freq = edx * 1000; /* back to kHz */ 243 244 pr_debug("low frequency is %u kHz\n", *low_freq); 245 246 if (*low_freq > *high_freq) 247 *low_freq = *high_freq; 248 249 return 0; 250 } 251 252 253 static int longrun_cpu_init(struct cpufreq_policy *policy) 254 { 255 int result = 0; 256 257 /* capability check */ 258 if (policy->cpu != 0) 259 return -ENODEV; 260 261 /* detect low and high frequency */ 262 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 263 if (result) 264 return result; 265 266 /* cpuinfo and default policy values */ 267 policy->cpuinfo.min_freq = longrun_low_freq; 268 policy->cpuinfo.max_freq = longrun_high_freq; 269 longrun_get_policy(policy); 270 271 return 0; 272 } 273 274 275 static struct cpufreq_driver longrun_driver = { 276 .flags = CPUFREQ_CONST_LOOPS, 277 .verify = longrun_verify_policy, 278 .setpolicy = longrun_set_policy, 279 .get = longrun_get, 280 .init = longrun_cpu_init, 281 .name = "longrun", 282 }; 283 284 static const struct x86_cpu_id longrun_ids[] = { 285 X86_MATCH_VENDOR_FEATURE(TRANSMETA, X86_FEATURE_LONGRUN, NULL), 286 {} 287 }; 288 MODULE_DEVICE_TABLE(x86cpu, longrun_ids); 289 290 /** 291 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 292 * 293 * Initializes the LongRun support. 294 */ 295 static int __init longrun_init(void) 296 { 297 if (!x86_match_cpu(longrun_ids)) 298 return -ENODEV; 299 return cpufreq_register_driver(&longrun_driver); 300 } 301 302 303 /** 304 * longrun_exit - unregisters LongRun support 305 */ 306 static void __exit longrun_exit(void) 307 { 308 cpufreq_unregister_driver(&longrun_driver); 309 } 310 311 312 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 313 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 314 "Efficeon processors."); 315 MODULE_LICENSE("GPL"); 316 317 module_init(longrun_init); 318 module_exit(longrun_exit); 319