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 static int elanfreq_target(struct cpufreq_policy *policy, 169 unsigned int target_freq, 170 unsigned int relation) 171 { 172 unsigned int newstate = 0; 173 174 if (cpufreq_frequency_table_target(policy, &elanfreq_table[0], 175 target_freq, relation, &newstate)) 176 return -EINVAL; 177 178 elanfreq_set_cpu_state(policy, newstate); 179 180 return 0; 181 } 182 183 184 /* 185 * Module init and exit code 186 */ 187 188 static int elanfreq_cpu_init(struct cpufreq_policy *policy) 189 { 190 struct cpuinfo_x86 *c = &cpu_data(0); 191 unsigned int i; 192 193 /* capability check */ 194 if ((c->x86_vendor != X86_VENDOR_AMD) || 195 (c->x86 != 4) || (c->x86_model != 10)) 196 return -ENODEV; 197 198 /* max freq */ 199 if (!max_freq) 200 max_freq = elanfreq_get_cpu_frequency(0); 201 202 /* table init */ 203 for (i = 0; (elanfreq_table[i].frequency != CPUFREQ_TABLE_END); i++) { 204 if (elanfreq_table[i].frequency > max_freq) 205 elanfreq_table[i].frequency = CPUFREQ_ENTRY_INVALID; 206 } 207 208 /* cpuinfo and default policy values */ 209 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 210 211 return cpufreq_table_validate_and_show(policy, elanfreq_table); 212 } 213 214 215 #ifndef MODULE 216 /** 217 * elanfreq_setup - elanfreq command line parameter parsing 218 * 219 * elanfreq command line parameter. Use: 220 * elanfreq=66000 221 * to set the maximum CPU frequency to 66 MHz. Note that in 222 * case you do not give this boot parameter, the maximum 223 * frequency will fall back to _current_ CPU frequency which 224 * might be lower. If you build this as a module, use the 225 * max_freq module parameter instead. 226 */ 227 static int __init elanfreq_setup(char *str) 228 { 229 max_freq = simple_strtoul(str, &str, 0); 230 printk(KERN_WARNING "You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n"); 231 return 1; 232 } 233 __setup("elanfreq=", elanfreq_setup); 234 #endif 235 236 237 static struct cpufreq_driver elanfreq_driver = { 238 .get = elanfreq_get_cpu_frequency, 239 .verify = cpufreq_generic_frequency_table_verify, 240 .target = elanfreq_target, 241 .init = elanfreq_cpu_init, 242 .exit = cpufreq_generic_exit, 243 .name = "elanfreq", 244 .attr = cpufreq_generic_attr, 245 }; 246 247 static const struct x86_cpu_id elan_id[] = { 248 { X86_VENDOR_AMD, 4, 10, }, 249 {} 250 }; 251 MODULE_DEVICE_TABLE(x86cpu, elan_id); 252 253 static int __init elanfreq_init(void) 254 { 255 if (!x86_match_cpu(elan_id)) 256 return -ENODEV; 257 return cpufreq_register_driver(&elanfreq_driver); 258 } 259 260 261 static void __exit elanfreq_exit(void) 262 { 263 cpufreq_unregister_driver(&elanfreq_driver); 264 } 265 266 267 module_param(max_freq, int, 0444); 268 269 MODULE_LICENSE("GPL"); 270 MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, " 271 "Sven Geggus <sven@geggus.net>"); 272 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs"); 273 274 module_init(elanfreq_init); 275 module_exit(elanfreq_exit); 276