1 /* 2 * sc520_freq.c: cpufreq driver for the AMD Elan sc520 3 * 4 * Copyright (C) 2005 Sean Young <sean@mess.org> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * Based on elanfreq.c 12 * 13 * 2005-03-30: - initial revision 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/init.h> 19 20 #include <linux/delay.h> 21 #include <linux/cpufreq.h> 22 #include <linux/timex.h> 23 #include <linux/io.h> 24 25 #include <asm/msr.h> 26 27 #define MMCR_BASE 0xfffef000 /* The default base address */ 28 #define OFFS_CPUCTL 0x2 /* CPU Control Register */ 29 30 static __u8 __iomem *cpuctl; 31 32 #define PFX "sc520_freq: " 33 34 static struct cpufreq_frequency_table sc520_freq_table[] = { 35 {0x01, 100000}, 36 {0x02, 133000}, 37 {0, CPUFREQ_TABLE_END}, 38 }; 39 40 static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu) 41 { 42 u8 clockspeed_reg = *cpuctl; 43 44 switch (clockspeed_reg & 0x03) { 45 default: 46 printk(KERN_ERR PFX "error: cpuctl register has unexpected " 47 "value %02x\n", clockspeed_reg); 48 case 0x01: 49 return 100000; 50 case 0x02: 51 return 133000; 52 } 53 } 54 55 static void sc520_freq_set_cpu_state(unsigned int state) 56 { 57 58 struct cpufreq_freqs freqs; 59 u8 clockspeed_reg; 60 61 freqs.old = sc520_freq_get_cpu_frequency(0); 62 freqs.new = sc520_freq_table[state].frequency; 63 freqs.cpu = 0; /* AMD Elan is UP */ 64 65 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); 66 67 pr_debug("attempting to set frequency to %i kHz\n", 68 sc520_freq_table[state].frequency); 69 70 local_irq_disable(); 71 72 clockspeed_reg = *cpuctl & ~0x03; 73 *cpuctl = clockspeed_reg | sc520_freq_table[state].index; 74 75 local_irq_enable(); 76 77 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); 78 }; 79 80 static int sc520_freq_verify(struct cpufreq_policy *policy) 81 { 82 return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]); 83 } 84 85 static int sc520_freq_target(struct cpufreq_policy *policy, 86 unsigned int target_freq, 87 unsigned int relation) 88 { 89 unsigned int newstate = 0; 90 91 if (cpufreq_frequency_table_target(policy, sc520_freq_table, 92 target_freq, relation, &newstate)) 93 return -EINVAL; 94 95 sc520_freq_set_cpu_state(newstate); 96 97 return 0; 98 } 99 100 101 /* 102 * Module init and exit code 103 */ 104 105 static int sc520_freq_cpu_init(struct cpufreq_policy *policy) 106 { 107 struct cpuinfo_x86 *c = &cpu_data(0); 108 int result; 109 110 /* capability check */ 111 if (c->x86_vendor != X86_VENDOR_AMD || 112 c->x86 != 4 || c->x86_model != 9) 113 return -ENODEV; 114 115 /* cpuinfo and default policy values */ 116 policy->cpuinfo.transition_latency = 1000000; /* 1ms */ 117 policy->cur = sc520_freq_get_cpu_frequency(0); 118 119 result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table); 120 if (result) 121 return result; 122 123 cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu); 124 125 return 0; 126 } 127 128 129 static int sc520_freq_cpu_exit(struct cpufreq_policy *policy) 130 { 131 cpufreq_frequency_table_put_attr(policy->cpu); 132 return 0; 133 } 134 135 136 static struct freq_attr *sc520_freq_attr[] = { 137 &cpufreq_freq_attr_scaling_available_freqs, 138 NULL, 139 }; 140 141 142 static struct cpufreq_driver sc520_freq_driver = { 143 .get = sc520_freq_get_cpu_frequency, 144 .verify = sc520_freq_verify, 145 .target = sc520_freq_target, 146 .init = sc520_freq_cpu_init, 147 .exit = sc520_freq_cpu_exit, 148 .name = "sc520_freq", 149 .owner = THIS_MODULE, 150 .attr = sc520_freq_attr, 151 }; 152 153 154 static int __init sc520_freq_init(void) 155 { 156 struct cpuinfo_x86 *c = &cpu_data(0); 157 int err; 158 159 /* Test if we have the right hardware */ 160 if (c->x86_vendor != X86_VENDOR_AMD || 161 c->x86 != 4 || c->x86_model != 9) { 162 pr_debug("no Elan SC520 processor found!\n"); 163 return -ENODEV; 164 } 165 cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1); 166 if (!cpuctl) { 167 printk(KERN_ERR "sc520_freq: error: failed to remap memory\n"); 168 return -ENOMEM; 169 } 170 171 err = cpufreq_register_driver(&sc520_freq_driver); 172 if (err) 173 iounmap(cpuctl); 174 175 return err; 176 } 177 178 179 static void __exit sc520_freq_exit(void) 180 { 181 cpufreq_unregister_driver(&sc520_freq_driver); 182 iounmap(cpuctl); 183 } 184 185 186 MODULE_LICENSE("GPL"); 187 MODULE_AUTHOR("Sean Young <sean@mess.org>"); 188 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU"); 189 190 module_init(sc520_freq_init); 191 module_exit(sc520_freq_exit); 192 193