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, 0, 1000}, 60 {0, 1, 2000}, 61 {0, 2, 4000}, 62 {0, 3, 8000}, 63 {0, 4, 16000}, 64 {0, 5, 33000}, 65 {0, 6, 66000}, 66 {0, 7, 99000}, 67 {0, 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 static int elanfreq_target(struct cpufreq_policy *policy, 109 unsigned int state) 110 { 111 /* 112 * Access to the Elan's internal registers is indexed via 113 * 0x22: Chip Setup & Control Register Index Register (CSCI) 114 * 0x23: Chip Setup & Control Register Data Register (CSCD) 115 * 116 */ 117 118 /* 119 * 0x40 is the Power Management Unit's Force Mode Register. 120 * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency) 121 */ 122 123 local_irq_disable(); 124 outb_p(0x40, REG_CSCIR); /* Disable hyperspeed mode */ 125 outb_p(0x00, REG_CSCDR); 126 local_irq_enable(); /* wait till internal pipelines and */ 127 udelay(1000); /* buffers have cleaned up */ 128 129 local_irq_disable(); 130 131 /* now, set the CPU clock speed register (0x80) */ 132 outb_p(0x80, REG_CSCIR); 133 outb_p(elan_multiplier[state].val80h, REG_CSCDR); 134 135 /* now, the hyperspeed bit in PMU Force Mode Register (0x40) */ 136 outb_p(0x40, REG_CSCIR); 137 outb_p(elan_multiplier[state].val40h, REG_CSCDR); 138 udelay(10000); 139 local_irq_enable(); 140 141 return 0; 142 } 143 /* 144 * Module init and exit code 145 */ 146 147 static int elanfreq_cpu_init(struct cpufreq_policy *policy) 148 { 149 struct cpuinfo_x86 *c = &cpu_data(0); 150 struct cpufreq_frequency_table *pos; 151 152 /* capability check */ 153 if ((c->x86_vendor != X86_VENDOR_AMD) || 154 (c->x86 != 4) || (c->x86_model != 10)) 155 return -ENODEV; 156 157 /* max freq */ 158 if (!max_freq) 159 max_freq = elanfreq_get_cpu_frequency(0); 160 161 /* table init */ 162 cpufreq_for_each_entry(pos, elanfreq_table) 163 if (pos->frequency > max_freq) 164 pos->frequency = CPUFREQ_ENTRY_INVALID; 165 166 /* cpuinfo and default policy values */ 167 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; 168 169 return cpufreq_table_validate_and_show(policy, elanfreq_table); 170 } 171 172 173 #ifndef MODULE 174 /** 175 * elanfreq_setup - elanfreq command line parameter parsing 176 * 177 * elanfreq command line parameter. Use: 178 * elanfreq=66000 179 * to set the maximum CPU frequency to 66 MHz. Note that in 180 * case you do not give this boot parameter, the maximum 181 * frequency will fall back to _current_ CPU frequency which 182 * might be lower. If you build this as a module, use the 183 * max_freq module parameter instead. 184 */ 185 static int __init elanfreq_setup(char *str) 186 { 187 max_freq = simple_strtoul(str, &str, 0); 188 printk(KERN_WARNING "You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n"); 189 return 1; 190 } 191 __setup("elanfreq=", elanfreq_setup); 192 #endif 193 194 195 static struct cpufreq_driver elanfreq_driver = { 196 .get = elanfreq_get_cpu_frequency, 197 .verify = cpufreq_generic_frequency_table_verify, 198 .target_index = elanfreq_target, 199 .init = elanfreq_cpu_init, 200 .name = "elanfreq", 201 .attr = cpufreq_generic_attr, 202 }; 203 204 static const struct x86_cpu_id elan_id[] = { 205 { X86_VENDOR_AMD, 4, 10, }, 206 {} 207 }; 208 MODULE_DEVICE_TABLE(x86cpu, elan_id); 209 210 static int __init elanfreq_init(void) 211 { 212 if (!x86_match_cpu(elan_id)) 213 return -ENODEV; 214 return cpufreq_register_driver(&elanfreq_driver); 215 } 216 217 218 static void __exit elanfreq_exit(void) 219 { 220 cpufreq_unregister_driver(&elanfreq_driver); 221 } 222 223 224 module_param(max_freq, int, 0444); 225 226 MODULE_LICENSE("GPL"); 227 MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, " 228 "Sven Geggus <sven@geggus.net>"); 229 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs"); 230 231 module_init(elanfreq_init); 232 module_exit(elanfreq_exit); 233