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/cpu_device_id.h> 26 #include <asm/msr.h> 27 28 #define MMCR_BASE 0xfffef000 /* The default base address */ 29 #define OFFS_CPUCTL 0x2 /* CPU Control Register */ 30 31 static __u8 __iomem *cpuctl; 32 33 #define PFX "sc520_freq: " 34 35 static struct cpufreq_frequency_table sc520_freq_table[] = { 36 {0x01, 100000}, 37 {0x02, 133000}, 38 {0, CPUFREQ_TABLE_END}, 39 }; 40 41 static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu) 42 { 43 u8 clockspeed_reg = *cpuctl; 44 45 switch (clockspeed_reg & 0x03) { 46 default: 47 printk(KERN_ERR PFX "error: cpuctl register has unexpected " 48 "value %02x\n", clockspeed_reg); 49 case 0x01: 50 return 100000; 51 case 0x02: 52 return 133000; 53 } 54 } 55 56 static void sc520_freq_set_cpu_state(unsigned int state) 57 { 58 59 struct cpufreq_freqs freqs; 60 u8 clockspeed_reg; 61 62 freqs.old = sc520_freq_get_cpu_frequency(0); 63 freqs.new = sc520_freq_table[state].frequency; 64 freqs.cpu = 0; /* AMD Elan is UP */ 65 66 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); 67 68 pr_debug("attempting to set frequency to %i kHz\n", 69 sc520_freq_table[state].frequency); 70 71 local_irq_disable(); 72 73 clockspeed_reg = *cpuctl & ~0x03; 74 *cpuctl = clockspeed_reg | sc520_freq_table[state].index; 75 76 local_irq_enable(); 77 78 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); 79 }; 80 81 static int sc520_freq_verify(struct cpufreq_policy *policy) 82 { 83 return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]); 84 } 85 86 static int sc520_freq_target(struct cpufreq_policy *policy, 87 unsigned int target_freq, 88 unsigned int relation) 89 { 90 unsigned int newstate = 0; 91 92 if (cpufreq_frequency_table_target(policy, sc520_freq_table, 93 target_freq, relation, &newstate)) 94 return -EINVAL; 95 96 sc520_freq_set_cpu_state(newstate); 97 98 return 0; 99 } 100 101 102 /* 103 * Module init and exit code 104 */ 105 106 static int sc520_freq_cpu_init(struct cpufreq_policy *policy) 107 { 108 struct cpuinfo_x86 *c = &cpu_data(0); 109 int result; 110 111 /* capability check */ 112 if (c->x86_vendor != X86_VENDOR_AMD || 113 c->x86 != 4 || c->x86_model != 9) 114 return -ENODEV; 115 116 /* cpuinfo and default policy values */ 117 policy->cpuinfo.transition_latency = 1000000; /* 1ms */ 118 policy->cur = sc520_freq_get_cpu_frequency(0); 119 120 result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table); 121 if (result) 122 return result; 123 124 cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu); 125 126 return 0; 127 } 128 129 130 static int sc520_freq_cpu_exit(struct cpufreq_policy *policy) 131 { 132 cpufreq_frequency_table_put_attr(policy->cpu); 133 return 0; 134 } 135 136 137 static struct freq_attr *sc520_freq_attr[] = { 138 &cpufreq_freq_attr_scaling_available_freqs, 139 NULL, 140 }; 141 142 143 static struct cpufreq_driver sc520_freq_driver = { 144 .get = sc520_freq_get_cpu_frequency, 145 .verify = sc520_freq_verify, 146 .target = sc520_freq_target, 147 .init = sc520_freq_cpu_init, 148 .exit = sc520_freq_cpu_exit, 149 .name = "sc520_freq", 150 .owner = THIS_MODULE, 151 .attr = sc520_freq_attr, 152 }; 153 154 static const struct x86_cpu_id sc520_ids[] = { 155 { X86_VENDOR_AMD, 4, 9 }, 156 {} 157 }; 158 MODULE_DEVICE_TABLE(x86cpu, sc520_ids); 159 160 static int __init sc520_freq_init(void) 161 { 162 int err; 163 164 if (!x86_match_cpu(sc520_ids)) 165 return -ENODEV; 166 167 cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1); 168 if (!cpuctl) { 169 printk(KERN_ERR "sc520_freq: error: failed to remap memory\n"); 170 return -ENOMEM; 171 } 172 173 err = cpufreq_register_driver(&sc520_freq_driver); 174 if (err) 175 iounmap(cpuctl); 176 177 return err; 178 } 179 180 181 static void __exit sc520_freq_exit(void) 182 { 183 cpufreq_unregister_driver(&sc520_freq_driver); 184 iounmap(cpuctl); 185 } 186 187 188 MODULE_LICENSE("GPL"); 189 MODULE_AUTHOR("Sean Young <sean@mess.org>"); 190 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU"); 191 192 module_init(sc520_freq_init); 193 module_exit(sc520_freq_exit); 194 195