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/msr.h>
  20
  21#define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
  22                                           as it is unused */
  23
  24#define PFX "powernow-k6: "
  25static unsigned int                     busfreq;   /* FSB, in 10 kHz */
  26static unsigned int                     max_multiplier;
  27
  28
  29/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
  30static struct cpufreq_frequency_table clock_ratio[] = {
  31        {45,  /* 000 -> 4.5x */ 0},
  32        {50,  /* 001 -> 5.0x */ 0},
  33        {40,  /* 010 -> 4.0x */ 0},
  34        {55,  /* 011 -> 5.5x */ 0},
  35        {20,  /* 100 -> 2.0x */ 0},
  36        {30,  /* 101 -> 3.0x */ 0},
  37        {60,  /* 110 -> 6.0x */ 0},
  38        {35,  /* 111 -> 3.5x */ 0},
  39        {0, CPUFREQ_TABLE_END}
  40};
  41
  42
  43/**
  44 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
  45 *
  46 *   Returns the current setting of the frequency multiplier. Core clock
  47 * speed is frequency of the Front-Side Bus multiplied with this value.
  48 */
  49static int powernow_k6_get_cpu_multiplier(void)
  50{
  51        u64 invalue = 0;
  52        u32 msrval;
  53
  54        msrval = POWERNOW_IOPORT + 0x1;
  55        wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  56        invalue = inl(POWERNOW_IOPORT + 0x8);
  57        msrval = POWERNOW_IOPORT + 0x0;
  58        wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
  59
  60        return clock_ratio[(invalue >> 5)&7].index;
  61}
  62
  63
  64/**
  65 * powernow_k6_set_state - set the PowerNow! multiplier
  66 * @best_i: clock_ratio[best_i] is the target multiplier
  67 *
  68 *   Tries to change the PowerNow! multiplier
  69 */
  70static void powernow_k6_set_state(unsigned int best_i)
  71{
  72        unsigned long outvalue = 0, invalue = 0;
  73        unsigned long msrval;
  74        struct cpufreq_freqs freqs;
  75
  76        if (clock_ratio[best_i].index > max_multiplier) {
  77                printk(KERN_ERR PFX "invalid target frequency\n");
  78                return;
  79        }
  80
  81        freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
  82        freqs.new = busfreq * clock_ratio[best_i].index;
  83        freqs.cpu = 0; /* powernow-k6.c is UP only driver */
  84
  85        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  86
  87        /* we now need to transform best_i to the BVC format, see AMD#23446 */
  88
  89        outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);
  90
  91        msrval = POWERNOW_IOPORT + 0x1;
  92        wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  93        invalue = inl(POWERNOW_IOPORT + 0x8);
  94        invalue = invalue & 0xf;
  95        outvalue = outvalue | invalue;
  96        outl(outvalue , (POWERNOW_IOPORT + 0x8));
  97        msrval = POWERNOW_IOPORT + 0x0;
  98        wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
  99
 100        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 101
 102        return;
 103}
 104
 105
 106/**
 107 * powernow_k6_verify - verifies a new CPUfreq policy
 108 * @policy: new policy
 109 *
 110 * Policy must be within lowest and highest possible CPU Frequency,
 111 * and at least one possible state must be within min and max.
 112 */
 113static int powernow_k6_verify(struct cpufreq_policy *policy)
 114{
 115        return cpufreq_frequency_table_verify(policy, &clock_ratio[0]);
 116}
 117
 118
 119/**
 120 * powernow_k6_setpolicy - sets a new CPUFreq policy
 121 * @policy: new policy
 122 * @target_freq: the target frequency
 123 * @relation: how that frequency relates to achieved frequency
 124 *  (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
 125 *
 126 * sets a new CPUFreq policy
 127 */
 128static int powernow_k6_target(struct cpufreq_policy *policy,
 129                               unsigned int target_freq,
 130                               unsigned int relation)
 131{
 132        unsigned int newstate = 0;
 133
 134        if (cpufreq_frequency_table_target(policy, &clock_ratio[0],
 135                                target_freq, relation, &newstate))
 136                return -EINVAL;
 137
 138        powernow_k6_set_state(newstate);
 139
 140        return 0;
 141}
 142
 143
 144static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
 145{
 146        unsigned int i, f;
 147        int result;
 148
 149        if (policy->cpu != 0)
 150                return -ENODEV;
 151
 152        /* get frequencies */
 153        max_multiplier = powernow_k6_get_cpu_multiplier();
 154        busfreq = cpu_khz / max_multiplier;
 155
 156        /* table init */
 157        for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
 158                f = clock_ratio[i].index;
 159                if (f > max_multiplier)
 160                        clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
 161                else
 162                        clock_ratio[i].frequency = busfreq * f;
 163        }
 164
 165        /* cpuinfo and default policy values */
 166        policy->cpuinfo.transition_latency = 200000;
 167        policy->cur = busfreq * max_multiplier;
 168
 169        result = cpufreq_frequency_table_cpuinfo(policy, clock_ratio);
 170        if (result)
 171                return result;
 172
 173        cpufreq_frequency_table_get_attr(clock_ratio, policy->cpu);
 174
 175        return 0;
 176}
 177
 178
 179static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
 180{
 181        unsigned int i;
 182        for (i = 0; i < 8; i++) {
 183                if (i == max_multiplier)
 184                        powernow_k6_set_state(i);
 185        }
 186        cpufreq_frequency_table_put_attr(policy->cpu);
 187        return 0;
 188}
 189
 190static unsigned int powernow_k6_get(unsigned int cpu)
 191{
 192        unsigned int ret;
 193        ret = (busfreq * powernow_k6_get_cpu_multiplier());
 194        return ret;
 195}
 196
 197static struct freq_attr *powernow_k6_attr[] = {
 198        &cpufreq_freq_attr_scaling_available_freqs,
 199        NULL,
 200};
 201
 202static struct cpufreq_driver powernow_k6_driver = {
 203        .verify         = powernow_k6_verify,
 204        .target         = powernow_k6_target,
 205        .init           = powernow_k6_cpu_init,
 206        .exit           = powernow_k6_cpu_exit,
 207        .get            = powernow_k6_get,
 208        .name           = "powernow-k6",
 209        .owner          = THIS_MODULE,
 210        .attr           = powernow_k6_attr,
 211};
 212
 213
 214/**
 215 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
 216 *
 217 *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
 218 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
 219 * on success.
 220 */
 221static int __init powernow_k6_init(void)
 222{
 223        struct cpuinfo_x86 *c = &cpu_data(0);
 224
 225        if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 5) ||
 226                ((c->x86_model != 12) && (c->x86_model != 13)))
 227                return -ENODEV;
 228
 229        if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
 230                printk(KERN_INFO PFX "PowerNow IOPORT region already used.\n");
 231                return -EIO;
 232        }
 233
 234        if (cpufreq_register_driver(&powernow_k6_driver)) {
 235                release_region(POWERNOW_IOPORT, 16);
 236                return -EINVAL;
 237        }
 238
 239        return 0;
 240}
 241
 242
 243/**
 244 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
 245 *
 246 *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
 247 */
 248static void __exit powernow_k6_exit(void)
 249{
 250        cpufreq_unregister_driver(&powernow_k6_driver);
 251        release_region(POWERNOW_IOPORT, 16);
 252}
 253
 254
 255MODULE_AUTHOR("Arjan van de Ven, Dave Jones <davej@redhat.com>, "
 256                "Dominik Brodowski <linux@brodo.de>");
 257MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
 258MODULE_LICENSE("GPL");
 259
 260module_init(powernow_k6_init);
 261module_exit(powernow_k6_exit);
 262