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 struct msr msr; 39 40 rdmsrq(MSR_TMTA_LONGRUN_FLAGS, msr.q); 41 pr_debug("longrun flags are %x - %x\n", msr.l, msr.h); 42 if (msr.l & 0x01) 43 policy->policy = CPUFREQ_POLICY_PERFORMANCE; 44 else 45 policy->policy = CPUFREQ_POLICY_POWERSAVE; 46 47 rdmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q); 48 pr_debug("longrun ctrl is %x - %x\n", msr.l, msr.h); 49 msr.l &= 0x0000007F; 50 msr.h &= 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.l * 57 ((longrun_high_freq - longrun_low_freq) / 100); 58 policy->max = longrun_low_freq + msr.h * 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 struct msr msr; 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 rdmsrq(MSR_TMTA_LONGRUN_FLAGS, msr.q); 97 msr.l &= 0xFFFFFFFE; 98 switch (policy->policy) { 99 case CPUFREQ_POLICY_PERFORMANCE: 100 msr.l |= 0x00000001; 101 break; 102 case CPUFREQ_POLICY_POWERSAVE: 103 break; 104 } 105 wrmsrq(MSR_TMTA_LONGRUN_FLAGS, msr.q); 106 107 /* lower and upper boundary */ 108 rdmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q); 109 msr.l &= 0xFFFFFF80; 110 msr.h &= 0xFFFFFF80; 111 msr.l |= pctg_lo; 112 msr.h |= pctg_hi; 113 wrmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q); 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 struct msr msr, save; 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 rdmsrq(MSR_TMTA_LRTI_READOUT, msr.q); 181 msr.l = msr.h; 182 wrmsrq(MSR_TMTA_LRTI_READOUT, msr.q); 183 rdmsrq(MSR_TMTA_LRTI_VOLT_MHZ, msr.q); 184 *low_freq = msr.l * 1000; /* to kHz */ 185 186 /* maximum */ 187 msr.l = 0; 188 wrmsrq(MSR_TMTA_LRTI_READOUT, msr.q); 189 rdmsrq(MSR_TMTA_LRTI_VOLT_MHZ, msr.q); 190 *high_freq = msr.l * 1000; /* to kHz */ 191 192 pr_debug("longrun table interface told %u - %u kHz\n", 193 *low_freq, *high_freq); 194 195 if (*low_freq > *high_freq) 196 *low_freq = *high_freq; 197 return 0; 198 } 199 200 /* set the upper border to the value determined during TSC init */ 201 *high_freq = (cpu_khz / 1000); 202 *high_freq = *high_freq * 1000; 203 pr_debug("high frequency is %u kHz\n", *high_freq); 204 205 /* get current borders */ 206 rdmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q); 207 save.l = msr.l & 0x0000007F; 208 save.h = msr.h & 0x0000007F; 209 210 /* if current perf_pctg is larger than 90%, we need to decrease the 211 * upper limit to make the calculation more accurate. 212 */ 213 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 214 /* try decreasing in 10% steps, some processors react only 215 * on some barrier values */ 216 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 217 /* set to 0 to try_hi perf_pctg */ 218 msr.l &= 0xFFFFFF80; 219 msr.h &= 0xFFFFFF80; 220 msr.h |= try_hi; 221 wrmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q); 222 223 /* read out current core MHz and current perf_pctg */ 224 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 225 226 /* restore values */ 227 wrmsrq(MSR_TMTA_LONGRUN_CTRL, save.q); 228 } 229 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax); 230 231 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 232 * eqals 233 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 234 * 235 * high_freq * perf_pctg is stored tempoarily into "ebx". 236 */ 237 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 238 239 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 240 return -EIO; 241 242 edx = ((eax - ebx) * 100) / (100 - ecx); 243 *low_freq = edx * 1000; /* back to kHz */ 244 245 pr_debug("low frequency is %u kHz\n", *low_freq); 246 247 if (*low_freq > *high_freq) 248 *low_freq = *high_freq; 249 250 return 0; 251 } 252 253 254 static int longrun_cpu_init(struct cpufreq_policy *policy) 255 { 256 int result = 0; 257 258 /* capability check */ 259 if (policy->cpu != 0) 260 return -ENODEV; 261 262 /* detect low and high frequency */ 263 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 264 if (result) 265 return result; 266 267 /* cpuinfo and default policy values */ 268 policy->cpuinfo.min_freq = longrun_low_freq; 269 policy->cpuinfo.max_freq = longrun_high_freq; 270 longrun_get_policy(policy); 271 272 return 0; 273 } 274 275 276 static struct cpufreq_driver longrun_driver = { 277 .flags = CPUFREQ_CONST_LOOPS, 278 .verify = longrun_verify_policy, 279 .setpolicy = longrun_set_policy, 280 .get = longrun_get, 281 .init = longrun_cpu_init, 282 .name = "longrun", 283 }; 284 285 static const struct x86_cpu_id longrun_ids[] = { 286 X86_MATCH_VENDOR_FEATURE(TRANSMETA, X86_FEATURE_LONGRUN, NULL), 287 {} 288 }; 289 MODULE_DEVICE_TABLE(x86cpu, longrun_ids); 290 291 /** 292 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 293 * 294 * Initializes the LongRun support. 295 */ 296 static int __init longrun_init(void) 297 { 298 if (!x86_match_cpu(longrun_ids)) 299 return -ENODEV; 300 return cpufreq_register_driver(&longrun_driver); 301 } 302 303 304 /** 305 * longrun_exit - unregisters LongRun support 306 */ 307 static void __exit longrun_exit(void) 308 { 309 cpufreq_unregister_driver(&longrun_driver); 310 } 311 312 313 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 314 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 315 "Efficeon processors."); 316 MODULE_LICENSE("GPL"); 317 318 module_init(longrun_init); 319 module_exit(longrun_exit); 320