linux/drivers/cpufreq/powernow-k6.c
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   1/*
   2 *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
   3 *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne Pänkälä,
   4 *                 Dominik Brodowski.
   5 *
   6 *  Licensed under the terms of the GNU GPL License version 2.
   7 *
   8 *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   9 */
  10
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/init.h>
  14#include <linux/cpufreq.h>
  15#include <linux/ioport.h>
  16#include <linux/timex.h>
  17#include <linux/io.h>
  18
  19#include <asm/cpu_device_id.h>
  20#include <asm/msr.h>
  21
  22#define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
  23                                           as it is unused */
  24
  25#define PFX "powernow-k6: "
  26static unsigned int                     busfreq;   /* FSB, in 10 kHz */
  27static unsigned int                     max_multiplier;
  28
  29
  30/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
  31static struct cpufreq_frequency_table clock_ratio[] = {
  32        {45,  /* 000 -> 4.5x */ 0},
  33        {50,  /* 001 -> 5.0x */ 0},
  34        {40,  /* 010 -> 4.0x */ 0},
  35        {55,  /* 011 -> 5.5x */ 0},
  36        {20,  /* 100 -> 2.0x */ 0},
  37        {30,  /* 101 -> 3.0x */ 0},
  38        {60,  /* 110 -> 6.0x */ 0},
  39        {35,  /* 111 -> 3.5x */ 0},
  40        {0, CPUFREQ_TABLE_END}
  41};
  42
  43
  44/**
  45 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
  46 *
  47 *   Returns the current setting of the frequency multiplier. Core clock
  48 * speed is frequency of the Front-Side Bus multiplied with this value.
  49 */
  50static int powernow_k6_get_cpu_multiplier(void)
  51{
  52        u64 invalue = 0;
  53        u32 msrval;
  54
  55        msrval = POWERNOW_IOPORT + 0x1;
  56        wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  57        invalue = inl(POWERNOW_IOPORT + 0x8);
  58        msrval = POWERNOW_IOPORT + 0x0;
  59        wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
  60
  61        return clock_ratio[(invalue >> 5)&7].index;
  62}
  63
  64
  65/**
  66 * powernow_k6_set_state - set the PowerNow! multiplier
  67 * @best_i: clock_ratio[best_i] is the target multiplier
  68 *
  69 *   Tries to change the PowerNow! multiplier
  70 */
  71static void powernow_k6_set_state(unsigned int best_i)
  72{
  73        unsigned long outvalue = 0, invalue = 0;
  74        unsigned long msrval;
  75        struct cpufreq_freqs freqs;
  76
  77        if (clock_ratio[best_i].index > max_multiplier) {
  78                printk(KERN_ERR PFX "invalid target frequency\n");
  79                return;
  80        }
  81
  82        freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
  83        freqs.new = busfreq * clock_ratio[best_i].index;
  84        freqs.cpu = 0; /* powernow-k6.c is UP only driver */
  85
  86        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  87
  88        /* we now need to transform best_i to the BVC format, see AMD#23446 */
  89
  90        outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);
  91
  92        msrval = POWERNOW_IOPORT + 0x1;
  93        wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  94        invalue = inl(POWERNOW_IOPORT + 0x8);
  95        invalue = invalue & 0xf;
  96        outvalue = outvalue | invalue;
  97        outl(outvalue , (POWERNOW_IOPORT + 0x8));
  98        msrval = POWERNOW_IOPORT + 0x0;
  99        wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
 100
 101        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 102
 103        return;
 104}
 105
 106
 107/**
 108 * powernow_k6_verify - verifies a new CPUfreq policy
 109 * @policy: new policy
 110 *
 111 * Policy must be within lowest and highest possible CPU Frequency,
 112 * and at least one possible state must be within min and max.
 113 */
 114static int powernow_k6_verify(struct cpufreq_policy *policy)
 115{
 116        return cpufreq_frequency_table_verify(policy, &clock_ratio[0]);
 117}
 118
 119
 120/**
 121 * powernow_k6_setpolicy - sets a new CPUFreq policy
 122 * @policy: new policy
 123 * @target_freq: the target frequency
 124 * @relation: how that frequency relates to achieved frequency
 125 *  (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
 126 *
 127 * sets a new CPUFreq policy
 128 */
 129static int powernow_k6_target(struct cpufreq_policy *policy,
 130                               unsigned int target_freq,
 131                               unsigned int relation)
 132{
 133        unsigned int newstate = 0;
 134
 135        if (cpufreq_frequency_table_target(policy, &clock_ratio[0],
 136                                target_freq, relation, &newstate))
 137                return -EINVAL;
 138
 139        powernow_k6_set_state(newstate);
 140
 141        return 0;
 142}
 143
 144
 145static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
 146{
 147        unsigned int i, f;
 148        int result;
 149
 150        if (policy->cpu != 0)
 151                return -ENODEV;
 152
 153        /* get frequencies */
 154        max_multiplier = powernow_k6_get_cpu_multiplier();
 155        busfreq = cpu_khz / max_multiplier;
 156
 157        /* table init */
 158        for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
 159                f = clock_ratio[i].index;
 160                if (f > max_multiplier)
 161                        clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
 162                else
 163                        clock_ratio[i].frequency = busfreq * f;
 164        }
 165
 166        /* cpuinfo and default policy values */
 167        policy->cpuinfo.transition_latency = 200000;
 168        policy->cur = busfreq * max_multiplier;
 169
 170        result = cpufreq_frequency_table_cpuinfo(policy, clock_ratio);
 171        if (result)
 172                return result;
 173
 174        cpufreq_frequency_table_get_attr(clock_ratio, policy->cpu);
 175
 176        return 0;
 177}
 178
 179
 180static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
 181{
 182        unsigned int i;
 183        for (i = 0; i < 8; i++) {
 184                if (i == max_multiplier)
 185                        powernow_k6_set_state(i);
 186        }
 187        cpufreq_frequency_table_put_attr(policy->cpu);
 188        return 0;
 189}
 190
 191static unsigned int powernow_k6_get(unsigned int cpu)
 192{
 193        unsigned int ret;
 194        ret = (busfreq * powernow_k6_get_cpu_multiplier());
 195        return ret;
 196}
 197
 198static struct freq_attr *powernow_k6_attr[] = {
 199        &cpufreq_freq_attr_scaling_available_freqs,
 200        NULL,
 201};
 202
 203static struct cpufreq_driver powernow_k6_driver = {
 204        .verify         = powernow_k6_verify,
 205        .target         = powernow_k6_target,
 206        .init           = powernow_k6_cpu_init,
 207        .exit           = powernow_k6_cpu_exit,
 208        .get            = powernow_k6_get,
 209        .name           = "powernow-k6",
 210        .owner          = THIS_MODULE,
 211        .attr           = powernow_k6_attr,
 212};
 213
 214static const struct x86_cpu_id powernow_k6_ids[] = {
 215        { X86_VENDOR_AMD, 5, 12 },
 216        { X86_VENDOR_AMD, 5, 13 },
 217        {}
 218};
 219MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
 220
 221/**
 222 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
 223 *
 224 *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
 225 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
 226 * on success.
 227 */
 228static int __init powernow_k6_init(void)
 229{
 230        if (!x86_match_cpu(powernow_k6_ids))
 231                return -ENODEV;
 232
 233        if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
 234                printk(KERN_INFO PFX "PowerNow IOPORT region already used.\n");
 235                return -EIO;
 236        }
 237
 238        if (cpufreq_register_driver(&powernow_k6_driver)) {
 239                release_region(POWERNOW_IOPORT, 16);
 240                return -EINVAL;
 241        }
 242
 243        return 0;
 244}
 245
 246
 247/**
 248 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
 249 *
 250 *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
 251 */
 252static void __exit powernow_k6_exit(void)
 253{
 254        cpufreq_unregister_driver(&powernow_k6_driver);
 255        release_region(POWERNOW_IOPORT, 16);
 256}
 257
 258
 259MODULE_AUTHOR("Arjan van de Ven, Dave Jones <davej@redhat.com>, "
 260                "Dominik Brodowski <linux@brodo.de>");
 261MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
 262MODULE_LICENSE("GPL");
 263
 264module_init(powernow_k6_init);
 265module_exit(powernow_k6_exit);
 266
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