1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * This file was based upon code in Powertweak Linux (http://powertweak.sf.net) 4 * (C) 2000-2003 Dave Jones, Arjan van de Ven, Janne Pänkälä, 5 * Dominik Brodowski. 6 * 7 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous* 8 */ 9 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 11 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/cpufreq.h> 16 #include <linux/ioport.h> 17 #include <linux/timex.h> 18 #include <linux/io.h> 19 20 #include <asm/cpu_device_id.h> 21 #include <asm/msr.h> 22 23 #define POWERNOW_IOPORT 0xfff0 /* it doesn't matter where, as long 24 as it is unused */ 25 26 static unsigned int busfreq; /* FSB, in 10 kHz */ 27 static unsigned int max_multiplier; 28 29 static unsigned int param_busfreq = 0; 30 static unsigned int param_max_multiplier = 0; 31 32 module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO); 33 MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)"); 34 35 module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO); 36 MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz"); 37 38 /* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */ 39 static struct cpufreq_frequency_table clock_ratio[] = { 40 {0, 60, /* 110 -> 6.0x */ 0}, 41 {0, 55, /* 011 -> 5.5x */ 0}, 42 {0, 50, /* 001 -> 5.0x */ 0}, 43 {0, 45, /* 000 -> 4.5x */ 0}, 44 {0, 40, /* 010 -> 4.0x */ 0}, 45 {0, 35, /* 111 -> 3.5x */ 0}, 46 {0, 30, /* 101 -> 3.0x */ 0}, 47 {0, 20, /* 100 -> 2.0x */ 0}, 48 {0, 0, CPUFREQ_TABLE_END} 49 }; 50 51 static const u8 index_to_register[8] = { 6, 3, 1, 0, 2, 7, 5, 4 }; 52 static const u8 register_to_index[8] = { 3, 2, 4, 1, 7, 6, 0, 5 }; 53 54 static const struct { 55 unsigned freq; 56 unsigned mult; 57 } usual_frequency_table[] = { 58 { 350000, 35 }, // 100 * 3.5 59 { 400000, 40 }, // 100 * 4 60 { 450000, 45 }, // 100 * 4.5 61 { 475000, 50 }, // 95 * 5 62 { 500000, 50 }, // 100 * 5 63 { 506250, 45 }, // 112.5 * 4.5 64 { 533500, 55 }, // 97 * 5.5 65 { 550000, 55 }, // 100 * 5.5 66 { 562500, 50 }, // 112.5 * 5 67 { 570000, 60 }, // 95 * 6 68 { 600000, 60 }, // 100 * 6 69 { 618750, 55 }, // 112.5 * 5.5 70 { 660000, 55 }, // 120 * 5.5 71 { 675000, 60 }, // 112.5 * 6 72 { 720000, 60 }, // 120 * 6 73 }; 74 75 #define FREQ_RANGE 3000 76 77 /** 78 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier 79 * 80 * Returns the current setting of the frequency multiplier. Core clock 81 * speed is frequency of the Front-Side Bus multiplied with this value. 82 */ 83 static int powernow_k6_get_cpu_multiplier(void) 84 { 85 unsigned long invalue = 0; 86 u32 msrval; 87 88 local_irq_disable(); 89 90 msrval = POWERNOW_IOPORT + 0x1; 91 wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */ 92 invalue = inl(POWERNOW_IOPORT + 0x8); 93 msrval = POWERNOW_IOPORT + 0x0; 94 wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */ 95 96 local_irq_enable(); 97 98 return clock_ratio[register_to_index[(invalue >> 5)&7]].driver_data; 99 } 100 101 static void powernow_k6_set_cpu_multiplier(unsigned int best_i) 102 { 103 unsigned long outvalue, invalue; 104 unsigned long msrval; 105 unsigned long cr0; 106 107 /* we now need to transform best_i to the BVC format, see AMD#23446 */ 108 109 /* 110 * The processor doesn't respond to inquiry cycles while changing the 111 * frequency, so we must disable cache. 112 */ 113 local_irq_disable(); 114 cr0 = read_cr0(); 115 write_cr0(cr0 | X86_CR0_CD); 116 wbinvd(); 117 118 outvalue = (1<<12) | (1<<10) | (1<<9) | (index_to_register[best_i]<<5); 119 120 msrval = POWERNOW_IOPORT + 0x1; 121 wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */ 122 invalue = inl(POWERNOW_IOPORT + 0x8); 123 invalue = invalue & 0x1f; 124 outvalue = outvalue | invalue; 125 outl(outvalue, (POWERNOW_IOPORT + 0x8)); 126 msrval = POWERNOW_IOPORT + 0x0; 127 wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */ 128 129 write_cr0(cr0); 130 local_irq_enable(); 131 } 132 133 /** 134 * powernow_k6_target - set the PowerNow! multiplier 135 * @best_i: clock_ratio[best_i] is the target multiplier 136 * 137 * Tries to change the PowerNow! multiplier 138 */ 139 static int powernow_k6_target(struct cpufreq_policy *policy, 140 unsigned int best_i) 141 { 142 143 if (clock_ratio[best_i].driver_data > max_multiplier) { 144 pr_err("invalid target frequency\n"); 145 return -EINVAL; 146 } 147 148 powernow_k6_set_cpu_multiplier(best_i); 149 150 return 0; 151 } 152 153 static int powernow_k6_cpu_init(struct cpufreq_policy *policy) 154 { 155 struct cpufreq_frequency_table *pos; 156 unsigned int i, f; 157 unsigned khz; 158 159 if (policy->cpu != 0) 160 return -ENODEV; 161 162 max_multiplier = 0; 163 khz = cpu_khz; 164 for (i = 0; i < ARRAY_SIZE(usual_frequency_table); i++) { 165 if (khz >= usual_frequency_table[i].freq - FREQ_RANGE && 166 khz <= usual_frequency_table[i].freq + FREQ_RANGE) { 167 khz = usual_frequency_table[i].freq; 168 max_multiplier = usual_frequency_table[i].mult; 169 break; 170 } 171 } 172 if (param_max_multiplier) { 173 cpufreq_for_each_entry(pos, clock_ratio) 174 if (pos->driver_data == param_max_multiplier) { 175 max_multiplier = param_max_multiplier; 176 goto have_max_multiplier; 177 } 178 pr_err("invalid max_multiplier parameter, valid parameters 20, 30, 35, 40, 45, 50, 55, 60\n"); 179 return -EINVAL; 180 } 181 182 if (!max_multiplier) { 183 pr_warn("unknown frequency %u, cannot determine current multiplier\n", 184 khz); 185 pr_warn("use module parameters max_multiplier and bus_frequency\n"); 186 return -EOPNOTSUPP; 187 } 188 189 have_max_multiplier: 190 param_max_multiplier = max_multiplier; 191 192 if (param_busfreq) { 193 if (param_busfreq >= 50000 && param_busfreq <= 150000) { 194 busfreq = param_busfreq / 10; 195 goto have_busfreq; 196 } 197 pr_err("invalid bus_frequency parameter, allowed range 50000 - 150000 kHz\n"); 198 return -EINVAL; 199 } 200 201 busfreq = khz / max_multiplier; 202 have_busfreq: 203 param_busfreq = busfreq * 10; 204 205 /* table init */ 206 cpufreq_for_each_entry(pos, clock_ratio) { 207 f = pos->driver_data; 208 if (f > max_multiplier) 209 pos->frequency = CPUFREQ_ENTRY_INVALID; 210 else 211 pos->frequency = busfreq * f; 212 } 213 214 /* cpuinfo and default policy values */ 215 policy->cpuinfo.transition_latency = 500000; 216 policy->freq_table = clock_ratio; 217 218 return 0; 219 } 220 221 222 static int powernow_k6_cpu_exit(struct cpufreq_policy *policy) 223 { 224 unsigned int i; 225 226 for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) { 227 if (clock_ratio[i].driver_data == max_multiplier) { 228 struct cpufreq_freqs freqs; 229 230 freqs.old = policy->cur; 231 freqs.new = clock_ratio[i].frequency; 232 freqs.flags = 0; 233 234 cpufreq_freq_transition_begin(policy, &freqs); 235 powernow_k6_target(policy, i); 236 cpufreq_freq_transition_end(policy, &freqs, 0); 237 break; 238 } 239 } 240 return 0; 241 } 242 243 static unsigned int powernow_k6_get(unsigned int cpu) 244 { 245 unsigned int ret; 246 ret = (busfreq * powernow_k6_get_cpu_multiplier()); 247 return ret; 248 } 249 250 static struct cpufreq_driver powernow_k6_driver = { 251 .verify = cpufreq_generic_frequency_table_verify, 252 .target_index = powernow_k6_target, 253 .init = powernow_k6_cpu_init, 254 .exit = powernow_k6_cpu_exit, 255 .get = powernow_k6_get, 256 .name = "powernow-k6", 257 .attr = cpufreq_generic_attr, 258 }; 259 260 static const struct x86_cpu_id powernow_k6_ids[] = { 261 { X86_VENDOR_AMD, 5, 12 }, 262 { X86_VENDOR_AMD, 5, 13 }, 263 {} 264 }; 265 MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids); 266 267 /** 268 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver 269 * 270 * Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported 271 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero 272 * on success. 273 */ 274 static int __init powernow_k6_init(void) 275 { 276 if (!x86_match_cpu(powernow_k6_ids)) 277 return -ENODEV; 278 279 if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) { 280 pr_info("PowerNow IOPORT region already used\n"); 281 return -EIO; 282 } 283 284 if (cpufreq_register_driver(&powernow_k6_driver)) { 285 release_region(POWERNOW_IOPORT, 16); 286 return -EINVAL; 287 } 288 289 return 0; 290 } 291 292 293 /** 294 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support 295 * 296 * Unregisters AMD K6-2+ / K6-3+ PowerNow! support. 297 */ 298 static void __exit powernow_k6_exit(void) 299 { 300 cpufreq_unregister_driver(&powernow_k6_driver); 301 release_region(POWERNOW_IOPORT, 16); 302 } 303 304 305 MODULE_AUTHOR("Arjan van de Ven, Dave Jones, " 306 "Dominik Brodowski <linux@brodo.de>"); 307 MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors."); 308 MODULE_LICENSE("GPL"); 309 310 module_init(powernow_k6_init); 311 module_exit(powernow_k6_exit); 312