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#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \ 19 "longrun", msg) 20 21static struct cpufreq_driver longrun_driver; 22 23/** 24 * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz 25 * values into per cent values. In TMTA microcode, the following is valid: 26 * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 27 */ 28static unsigned int longrun_low_freq, longrun_high_freq; 29 30 31/** 32 * longrun_get_policy - get the current LongRun policy 33 * @policy: struct cpufreq_policy where current policy is written into 34 * 35 * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS 36 * and MSR_TMTA_LONGRUN_CTRL 37 */ 38static void __init longrun_get_policy(struct cpufreq_policy *policy) 39{ 40 u32 msr_lo, msr_hi; 41 42 rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 43 dprintk("longrun flags are %x - %x\n", msr_lo, msr_hi); 44 if (msr_lo & 0x01) 45 policy->policy = CPUFREQ_POLICY_PERFORMANCE; 46 else 47 policy->policy = CPUFREQ_POLICY_POWERSAVE; 48 49 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 50 dprintk("longrun ctrl is %x - %x\n", msr_lo, msr_hi); 51 msr_lo &= 0x0000007F; 52 msr_hi &= 0x0000007F; 53 54 if (longrun_high_freq <= longrun_low_freq) { 55 /* Assume degenerate Longrun table */ 56 policy->min = policy->max = longrun_high_freq; 57 } else { 58 policy->min = longrun_low_freq + msr_lo * 59 ((longrun_high_freq - longrun_low_freq) / 100); 60 policy->max = longrun_low_freq + msr_hi * 61 ((longrun_high_freq - longrun_low_freq) / 100); 62 } 63 policy->cpu = 0; 64} 65 66 67/** 68 * longrun_set_policy - sets a new CPUFreq policy 69 * @policy: new policy 70 * 71 * Sets a new CPUFreq policy on LongRun-capable processors. This function 72 * has to be called with cpufreq_driver locked. 73 */ 74static int longrun_set_policy(struct cpufreq_policy *policy) 75{ 76 u32 msr_lo, msr_hi; 77 u32 pctg_lo, pctg_hi; 78 79 if (!policy) 80 return -EINVAL; 81 82 if (longrun_high_freq <= longrun_low_freq) { 83 /* Assume degenerate Longrun table */ 84 pctg_lo = pctg_hi = 100; 85 } else { 86 pctg_lo = (policy->min - longrun_low_freq) / 87 ((longrun_high_freq - longrun_low_freq) / 100); 88 pctg_hi = (policy->max - longrun_low_freq) / 89 ((longrun_high_freq - longrun_low_freq) / 100); 90 } 91 92 if (pctg_hi > 100) 93 pctg_hi = 100; 94 if (pctg_lo > pctg_hi) 95 pctg_lo = pctg_hi; 96 97 /* performance or economy mode */ 98 rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 99 msr_lo &= 0xFFFFFFFE; 100 switch (policy->policy) { 101 case CPUFREQ_POLICY_PERFORMANCE: 102 msr_lo |= 0x00000001; 103 break; 104 case CPUFREQ_POLICY_POWERSAVE: 105 break; 106 } 107 wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi); 108 109 /* lower and upper boundary */ 110 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 111 msr_lo &= 0xFFFFFF80; 112 msr_hi &= 0xFFFFFF80; 113 msr_lo |= pctg_lo; 114 msr_hi |= pctg_hi; 115 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 116 117 return 0; 118} 119 120 121/** 122 * longrun_verify_poliy - verifies a new CPUFreq policy 123 * @policy: the policy to verify 124 * 125 * Validates a new CPUFreq policy. This function has to be called with 126 * cpufreq_driver locked. 127 */ 128static int longrun_verify_policy(struct cpufreq_policy *policy) 129{ 130 if (!policy) 131 return -EINVAL; 132 133 policy->cpu = 0; 134 cpufreq_verify_within_limits(policy, 135 policy->cpuinfo.min_freq, 136 policy->cpuinfo.max_freq); 137 138 if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) && 139 (policy->policy != CPUFREQ_POLICY_PERFORMANCE)) 140 return -EINVAL; 141 142 return 0; 143} 144 145static unsigned int longrun_get(unsigned int cpu) 146{ 147 u32 eax, ebx, ecx, edx; 148 149 if (cpu) 150 return 0; 151 152 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 153 dprintk("cpuid eax is %u\n", eax); 154 155 return eax * 1000; 156} 157 158/** 159 * longrun_determine_freqs - determines the lowest and highest possible core frequency 160 * @low_freq: an int to put the lowest frequency into 161 * @high_freq: an int to put the highest frequency into 162 * 163 * Determines the lowest and highest possible core frequencies on this CPU. 164 * This is necessary to calculate the performance percentage according to 165 * TMTA rules: 166 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq) 167 */ 168static unsigned int __cpuinit longrun_determine_freqs(unsigned int *low_freq, 169 unsigned int *high_freq) 170{ 171 u32 msr_lo, msr_hi; 172 u32 save_lo, save_hi; 173 u32 eax, ebx, ecx, edx; 174 u32 try_hi; 175 struct cpuinfo_x86 *c = &cpu_data(0); 176 177 if (!low_freq || !high_freq) 178 return -EINVAL; 179 180 if (cpu_has(c, X86_FEATURE_LRTI)) { 181 /* if the LongRun Table Interface is present, the 182 * detection is a bit easier: 183 * For minimum frequency, read out the maximum 184 * level (msr_hi), write that into "currently 185 * selected level", and read out the frequency. 186 * For maximum frequency, read out level zero. 187 */ 188 /* minimum */ 189 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi); 190 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi); 191 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 192 *low_freq = msr_lo * 1000; /* to kHz */ 193 194 /* maximum */ 195 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi); 196 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi); 197 *high_freq = msr_lo * 1000; /* to kHz */ 198 199 dprintk("longrun table interface told %u - %u kHz\n", 200 *low_freq, *high_freq); 201 202 if (*low_freq > *high_freq) 203 *low_freq = *high_freq; 204 return 0; 205 } 206 207 /* set the upper border to the value determined during TSC init */ 208 *high_freq = (cpu_khz / 1000); 209 *high_freq = *high_freq * 1000; 210 dprintk("high frequency is %u kHz\n", *high_freq); 211 212 /* get current borders */ 213 rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 214 save_lo = msr_lo & 0x0000007F; 215 save_hi = msr_hi & 0x0000007F; 216 217 /* if current perf_pctg is larger than 90%, we need to decrease the 218 * upper limit to make the calculation more accurate. 219 */ 220 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 221 /* try decreasing in 10% steps, some processors react only 222 * on some barrier values */ 223 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) { 224 /* set to 0 to try_hi perf_pctg */ 225 msr_lo &= 0xFFFFFF80; 226 msr_hi &= 0xFFFFFF80; 227 msr_hi |= try_hi; 228 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi); 229 230 /* read out current core MHz and current perf_pctg */ 231 cpuid(0x80860007, &eax, &ebx, &ecx, &edx); 232 233 /* restore values */ 234 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi); 235 } 236 dprintk("percentage is %u %%, freq is %u MHz\n", ecx, eax); 237 238 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq) 239 * eqals 240 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg) 241 * 242 * high_freq * perf_pctg is stored tempoarily into "ebx". 243 */ 244 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */ 245 246 if ((ecx > 95) || (ecx == 0) || (eax < ebx)) 247 return -EIO; 248 249 edx = ((eax - ebx) * 100) / (100 - ecx); 250 *low_freq = edx * 1000; /* back to kHz */ 251 252 dprintk("low frequency is %u kHz\n", *low_freq); 253 254 if (*low_freq > *high_freq) 255 *low_freq = *high_freq; 256 257 return 0; 258} 259 260 261static int __cpuinit longrun_cpu_init(struct cpufreq_policy *policy) 262{ 263 int result = 0; 264 265 /* capability check */ 266 if (policy->cpu != 0) 267 return -ENODEV; 268 269 /* detect low and high frequency */ 270 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq); 271 if (result) 272 return result; 273 274 /* cpuinfo and default policy values */ 275 policy->cpuinfo.min_freq = longrun_low_freq; 276 policy->cpuinfo.max_freq = longrun_high_freq; 277 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 278 longrun_get_policy(policy); 279 280 return 0; 281} 282 283 284static struct cpufreq_driver longrun_driver = { 285 .flags = CPUFREQ_CONST_LOOPS, 286 .verify = longrun_verify_policy, 287 .setpolicy = longrun_set_policy, 288 .get = longrun_get, 289 .init = longrun_cpu_init, 290 .name = "longrun", 291 .owner = THIS_MODULE, 292}; 293 294 295/** 296 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver 297 * 298 * Initializes the LongRun support. 299 */ 300static int __init longrun_init(void) 301{ 302 struct cpuinfo_x86 *c = &cpu_data(0); 303 304 if (c->x86_vendor != X86_VENDOR_TRANSMETA || 305 !cpu_has(c, X86_FEATURE_LONGRUN)) 306 return -ENODEV; 307 308 return cpufreq_register_driver(&longrun_driver); 309} 310 311 312/** 313 * longrun_exit - unregisters LongRun support 314 */ 315static void __exit longrun_exit(void) 316{ 317 cpufreq_unregister_driver(&longrun_driver); 318} 319 320 321MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); 322MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and " 323 "Efficeon processors."); 324MODULE_LICENSE("GPL"); 325 326module_init(longrun_init); 327module_exit(longrun_exit); 328