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_data *policy) 126 { 127 if (!policy) 128 return -EINVAL; 129 130 policy->cpu = 0; 131 cpufreq_verify_within_cpu_limits(policy); 132 133 return 0; 134 } 135 136 static unsigned int longrun_get(unsigned int cpu) 137 { 138 u32 eax, ebx, ecx, edx; 139 140 if (cpu) 141 return 0; 142 143 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 144 pr_debug("cpuid eax is %u\n", eax); 145 146 return eax * 1000; 147 } 148 149 /** 150 * longrun_determine_freqs - determines the lowest and highest possible core frequency 151 * @low_freq: an int to put the lowest frequency into 152 * @high_freq: an int to put the highest frequency into 153 * 154 * Determines the lowest and highest possible core frequencies on this CPU. 155 * This is necessary to calculate the performance percentage according to 156 * TMTA rules: 157 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 158 */ 159 static int longrun_determine_freqs(unsigned int *low_freq, 160 unsigned int *high_freq) 161 { 162 u32 msr_lo, msr_hi; 163 u32 save_lo, save_hi; 164 u32 eax, ebx, ecx, edx; 165 u32 try_hi; 166 struct cpuinfo_x86 *c = &cpu_data(0); 167 168 if (!low_freq || !high_freq) 169 return -EINVAL; 170 171 if (cpu_has(c, X86_FEATURE_LRTI)) { 172 /* if the LongRun Table Interface is present, the 173 * detection is a bit easier: 174 * For minimum frequency, read out the maximum 175 * level (msr_hi), write that into "currently 176 * selected level", and read out the frequency. 177 * For maximum frequency, read out level zero. 178 */ 179 /* minimum */ 180 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 181 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 182 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 183 *low_freq = msr_lo * 1000; /* to kHz */ 184 185 /* maximum */ 186 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 187 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 188 *high_freq = msr_lo * 1000; /* to kHz */ 189 190 pr_debug("longrun table interface told %u - %u kHz\n", 191 *low_freq, *high_freq); 192 193 if (*low_freq > *high_freq) 194 *low_freq = *high_freq; 195 return 0; 196 } 197 198 /* set the upper border to the value determined during TSC init */ 199 *high_freq = (cpu_khz / 1000); 200 *high_freq = *high_freq * 1000; 201 pr_debug("high frequency is %u kHz\n", *high_freq); 202 203 /* get current borders */ 204 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 205 save_lo = msr_lo & 0x0000007F; 206 save_hi = msr_hi & 0x0000007F; 207 208 /* if current perf_pctg is larger than 90%, we need to decrease the 209 * upper limit to make the calculation more accurate. 210 */ 211 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 212 /* try decreasing in 10% steps, some processors react only 213 * on some barrier values */ 214 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 215 /* set to 0 to try_hi perf_pctg */ 216 msr_lo &= 0xFFFFFF80; 217 msr_hi &= 0xFFFFFF80; 218 msr_hi |= try_hi; 219 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 220 221 /* read out current core MHz and current perf_pctg */ 222 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 223 224 /* restore values */ 225 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 226 } 227 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 228 229 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 230 * eqals 231 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 232 * 233 * high_freq * perf_pctg is stored tempoarily into "ebx". 234 */ 235 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 236 237 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 238 return -EIO; 239 240 edx = ((eax - ebx) * 100) / (100 - ecx); 241 *low_freq = edx * 1000; /* back to kHz */ 242 243 pr_debug("low frequency is %u kHz\n", *low_freq); 244 245 if (*low_freq > *high_freq) 246 *low_freq = *high_freq; 247 248 return 0; 249 } 250 251 252 static int longrun_cpu_init(struct cpufreq_policy *policy) 253 { 254 int result = 0; 255 256 /* capability check */ 257 if (policy->cpu != 0) 258 return -ENODEV; 259 260 /* detect low and high frequency */ 261 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 262 if (result) 263 return result; 264 265 /* cpuinfo and default policy values */ 266 policy->cpuinfo.min_freq = longrun_low_freq; 267 policy->cpuinfo.max_freq = longrun_high_freq; 268 longrun_get_policy(policy); 269 270 return 0; 271 } 272 273 274 static struct cpufreq_driver longrun_driver = { 275 .flags = CPUFREQ_CONST_LOOPS, 276 .verify = longrun_verify_policy, 277 .setpolicy = longrun_set_policy, 278 .get = longrun_get, 279 .init = longrun_cpu_init, 280 .name = "longrun", 281 }; 282 283 static const struct x86_cpu_id longrun_ids[] = { 284 X86_MATCH_VENDOR_FEATURE(TRANSMETA, X86_FEATURE_LONGRUN, NULL), 285 {} 286 }; 287 MODULE_DEVICE_TABLE(x86cpu, longrun_ids); 288 289 /** 290 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 291 * 292 * Initializes the LongRun support. 293 */ 294 static int __init longrun_init(void) 295 { 296 if (!x86_match_cpu(longrun_ids)) 297 return -ENODEV; 298 return cpufreq_register_driver(&longrun_driver); 299 } 300 301 302 /** 303 * longrun_exit - unregisters LongRun support 304 */ 305 static void __exit longrun_exit(void) 306 { 307 cpufreq_unregister_driver(&longrun_driver); 308 } 309 310 311 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 312 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 313 "Efficeon processors."); 314 MODULE_LICENSE("GPL"); 315 316 module_init(longrun_init); 317 module_exit(longrun_exit); 318