1 /* 2 * elanfreq: cpufreq driver for the AMD ELAN family 3 * 4 * (c) Copyright 2002 Robert Schwebel <r.schwebel@pengutronix.de> 5 * 6 * Parts of this code are (c) Sven Geggus <sven@geggus.net> 7 * 8 * All Rights Reserved. 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 * 15 * 2002-02-13: - initial revision for 2.4.18-pre9 by Robert Schwebel 16 * 17 */ 18 19 #include <linux/kernel.h> 20 #include <linux/module.h> 21 #include <linux/init.h> 22 23 #include <linux/delay.h> 24 #include <linux/cpufreq.h> 25 26 #include <asm/cpu_device_id.h> 27 #include <asm/msr.h> 28 #include <linux/timex.h> 29 #include <linux/io.h> 30 31 #define REG_CSCIR 0x22 /* Chip Setup and Control Index Register */ 32 #define REG_CSCDR 0x23 /* Chip Setup and Control Data Register */ 33 34 /* Module parameter */ 35 static int max_freq; 36 37 struct s_elan_multiplier { 38 int clock; /* frequency in kHz */ 39 int val40h; /* PMU Force Mode register */ 40 int val80h; /* CPU Clock Speed Register */ 41 }; 42 43 /* 44 * It is important that the frequencies 45 * are listed in ascending order here! 46 */ 47 static struct s_elan_multiplier elan_multiplier[] = { 48 {1000, 0x02, 0x18}, 49 {2000, 0x02, 0x10}, 50 {4000, 0x02, 0x08}, 51 {8000, 0x00, 0x00}, 52 {16000, 0x00, 0x02}, 53 {33000, 0x00, 0x04}, 54 {66000, 0x01, 0x04}, 55 {99000, 0x01, 0x05} 56 }; 57 58 static struct cpufreq_frequency_table elanfreq_table[] = { 59 {0, 1000}, 60 {1, 2000}, 61 {2, 4000}, 62 {3, 8000}, 63 {4, 16000}, 64 {5, 33000}, 65 {6, 66000}, 66 {7, 99000}, 67 {0, CPUFREQ_TABLE_END}, 68 }; 69 70 71 /** 72 * elanfreq_get_cpu_frequency: determine current cpu speed 73 * 74 * Finds out at which frequency the CPU of the Elan SOC runs 75 * at the moment. Frequencies from 1 to 33 MHz are generated 76 * the normal way, 66 and 99 MHz are called "Hyperspeed Mode" 77 * and have the rest of the chip running with 33 MHz. 78 */ 79 80 static unsigned int elanfreq_get_cpu_frequency(unsigned int cpu) 81 { 82 u8 clockspeed_reg; /* Clock Speed Register */ 83 84 local_irq_disable(); 85 outb_p(0x80, REG_CSCIR); 86 clockspeed_reg = inb_p(REG_CSCDR); 87 local_irq_enable(); 88 89 if ((clockspeed_reg & 0xE0) == 0xE0) 90 return 0; 91 92 /* Are we in CPU clock multiplied mode (66/99 MHz)? */ 93 if ((clockspeed_reg & 0xE0) == 0xC0) { 94 if ((clockspeed_reg & 0x01) == 0) 95 return 66000; 96 else 97 return 99000; 98 } 99 100 /* 33 MHz is not 32 MHz... */ 101 if ((clockspeed_reg & 0xE0) == 0xA0) 102 return 33000; 103 104 return (1<<((clockspeed_reg & 0xE0) >> 5)) * 1000; 105 } 106 107 108 /** 109 * elanfreq_set_cpu_frequency: Change the CPU core frequency 110 * @cpu: cpu number 111 * @freq: frequency in kHz 112 * 113 * This function takes a frequency value and changes the CPU frequency 114 * according to this. Note that the frequency has to be checked by 115 * elanfreq_validatespeed() for correctness! 116 * 117 * There is no return value. 118 */ 119 120 static void elanfreq_set_cpu_state(struct cpufreq_policy *policy, 121 unsigned int state) 122 { 123 struct cpufreq_freqs freqs; 124 125 freqs.old = elanfreq_get_cpu_frequency(0); 126 freqs.new = elan_multiplier[state].clock; 127 128 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); 129 130 printk(KERN_INFO "elanfreq: attempting to set frequency to %i kHz\n", 131 elan_multiplier[state].clock); 132 133 134 /* 135 * Access to the Elan's internal registers is indexed via 136 * 0x22: Chip Setup & Control Register Index Register (CSCI) 137 * 0x23: Chip Setup & Control Register Data Register (CSCD) 138 * 139 */ 140 141 /* 142 * 0x40 is the Power Management Unit's Force Mode Register. 143 * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency) 144 */ 145 146 local_irq_disable(); 147 outb_p(0x40, REG_CSCIR); /* Disable hyperspeed mode */ 148 outb_p(0x00, REG_CSCDR); 149 local_irq_enable(); /* wait till internal pipelines and */ 150 udelay(1000); /* buffers have cleaned up */ 151 152 local_irq_disable(); 153 154 /* now, set the CPU clock speed register (0x80) */ 155 outb_p(0x80, REG_CSCIR); 156 outb_p(elan_multiplier[state].val80h, REG_CSCDR); 157 158 /* now, the hyperspeed bit in PMU Force Mode Register (0x40) */ 159 outb_p(0x40, REG_CSCIR); 160 outb_p(elan_multiplier[state].val40h, REG_CSCDR); 161 udelay(10000); 162 local_irq_enable(); 163 164 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); 165 }; 166 167 168 /** 169 * elanfreq_validatespeed: test if frequency range is valid 170 * @policy: the policy to validate 171 * 172 * This function checks if a given frequency range in kHz is valid 173 * for the hardware supported by the driver. 174 */ 175 176 static int elanfreq_verify(struct cpufreq_policy *policy) 177 { 178 return cpufreq_frequency_table_verify(policy, &elanfreq_table[0]); 179 } 180 181 static int elanfreq_target(struct cpufreq_policy *policy, 182 unsigned int target_freq, 183 unsigned int relation) 184 { 185 unsigned int newstate = 0; 186 187 if (cpufreq_frequency_table_target(policy, &elanfreq_table[0], 188 target_freq, relation, &newstate)) 189 return -EINVAL; 190 191 elanfreq_set_cpu_state(policy, newstate); 192 193 return 0; 194 } 195 196 197 /* 198 * Module init and exit code 199 */ 200 201 static int elanfreq_cpu_init(struct cpufreq_policy *policy) 202 { 203 struct cpuinfo_x86 *c = &cpu_data(0); 204 unsigned int i; 205 int result; 206 207 /* capability check */ 208 if ((c->x86_vendor != X86_VENDOR_AMD) || 209 (c->x86 != 4) || (c->x86_model != 10)) 210 return -ENODEV; 211 212 /* max freq */ 213 if (!max_freq) 214 max_freq = elanfreq_get_cpu_frequency(0); 215 216 /* table init */ 217 for (i = 0; (elanfreq_table[i].frequency != CPUFREQ_TABLE_END); i++) { 218 if (elanfreq_table[i].frequency > max_freq) 219 elanfreq_table[i].frequency = CPUFREQ_ENTRY_INVALID; 220 } 221 222 /* cpuinfo and default policy values */ 223 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 224 policy->cur = elanfreq_get_cpu_frequency(0); 225 226 result = cpufreq_frequency_table_cpuinfo(policy, elanfreq_table); 227 if (result) 228 return result; 229 230 cpufreq_frequency_table_get_attr(elanfreq_table, policy->cpu); 231 return 0; 232 } 233 234 235 static int elanfreq_cpu_exit(struct cpufreq_policy *policy) 236 { 237 cpufreq_frequency_table_put_attr(policy->cpu); 238 return 0; 239 } 240 241 242 #ifndef MODULE 243 /** 244 * elanfreq_setup - elanfreq command line parameter parsing 245 * 246 * elanfreq command line parameter. Use: 247 * elanfreq=66000 248 * to set the maximum CPU frequency to 66 MHz. Note that in 249 * case you do not give this boot parameter, the maximum 250 * frequency will fall back to _current_ CPU frequency which 251 * might be lower. If you build this as a module, use the 252 * max_freq module parameter instead. 253 */ 254 static int __init elanfreq_setup(char *str) 255 { 256 max_freq = simple_strtoul(str, &str, 0); 257 printk(KERN_WARNING "You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n"); 258 return 1; 259 } 260 __setup("elanfreq=", elanfreq_setup); 261 #endif 262 263 264 static struct freq_attr *elanfreq_attr[] = { 265 &cpufreq_freq_attr_scaling_available_freqs, 266 NULL, 267 }; 268 269 270 static struct cpufreq_driver elanfreq_driver = { 271 .get = elanfreq_get_cpu_frequency, 272 .verify = elanfreq_verify, 273 .target = elanfreq_target, 274 .init = elanfreq_cpu_init, 275 .exit = elanfreq_cpu_exit, 276 .name = "elanfreq", 277 .attr = elanfreq_attr, 278 }; 279 280 static const struct x86_cpu_id elan_id[] = { 281 { X86_VENDOR_AMD, 4, 10, }, 282 {} 283 }; 284 MODULE_DEVICE_TABLE(x86cpu, elan_id); 285 286 static int __init elanfreq_init(void) 287 { 288 if (!x86_match_cpu(elan_id)) 289 return -ENODEV; 290 return cpufreq_register_driver(&elanfreq_driver); 291 } 292 293 294 static void __exit elanfreq_exit(void) 295 { 296 cpufreq_unregister_driver(&elanfreq_driver); 297 } 298 299 300 module_param(max_freq, int, 0444); 301 302 MODULE_LICENSE("GPL"); 303 MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, " 304 "Sven Geggus <sven@geggus.net>"); 305 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs"); 306 307 module_init(elanfreq_init); 308 module_exit(elanfreq_exit); 309