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powernow-k6.c

/*
 *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
 *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne Pänkälä, Dominik Brodowski.
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *
 *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/ioport.h>
#include <linux/slab.h>

#include <asm/msr.h>
#include <asm/timex.h>
#include <asm/io.h>


#define POWERNOW_IOPORT 0xfff0         /* it doesn't matter where, as long
                                as it is unused */

static unsigned int                     busfreq;   /* FSB, in 10 kHz */
static unsigned int                     max_multiplier;


/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
static struct cpufreq_frequency_table clock_ratio[] = {
      {45,  /* 000 -> 4.5x */ 0},
      {50,  /* 001 -> 5.0x */ 0},
      {40,  /* 010 -> 4.0x */ 0},
      {55,  /* 011 -> 5.5x */ 0},
      {20,  /* 100 -> 2.0x */ 0},
      {30,  /* 101 -> 3.0x */ 0},
      {60,  /* 110 -> 6.0x */ 0},
      {35,  /* 111 -> 3.5x */ 0},
      {0, CPUFREQ_TABLE_END}
};


/**
 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
 *
 *   Returns the current setting of the frequency multiplier. Core clock
 * speed is frequency of the Front-Side Bus multiplied with this value.
 */
static int powernow_k6_get_cpu_multiplier(void)
{
      u64             invalue = 0;
      u32             msrval;

      msrval = POWERNOW_IOPORT + 0x1;
      wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
      invalue=inl(POWERNOW_IOPORT + 0x8);
      msrval = POWERNOW_IOPORT + 0x0;
      wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */

      return clock_ratio[(invalue >> 5)&7].index;
}


/**
 * powernow_k6_set_state - set the PowerNow! multiplier
 * @best_i: clock_ratio[best_i] is the target multiplier
 *
 *   Tries to change the PowerNow! multiplier
 */
static void powernow_k6_set_state (unsigned int best_i)
{
      unsigned long           outvalue=0, invalue=0;
      unsigned long           msrval;
      struct cpufreq_freqs    freqs;

      if (clock_ratio[best_i].index > max_multiplier) {
            printk(KERN_ERR "cpufreq: invalid target frequency\n");
            return;
      }

      freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
      freqs.new = busfreq * clock_ratio[best_i].index;
      freqs.cpu = 0; /* powernow-k6.c is UP only driver */

      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

      /* we now need to transform best_i to the BVC format, see AMD#23446 */

      outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);

      msrval = POWERNOW_IOPORT + 0x1;
      wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
      invalue=inl(POWERNOW_IOPORT + 0x8);
      invalue = invalue & 0xf;
      outvalue = outvalue | invalue;
      outl(outvalue ,(POWERNOW_IOPORT + 0x8));
      msrval = POWERNOW_IOPORT + 0x0;
      wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */

      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return;
}


/**
 * powernow_k6_verify - verifies a new CPUfreq policy
 * @policy: new policy
 *
 * Policy must be within lowest and highest possible CPU Frequency,
 * and at least one possible state must be within min and max.
 */
static int powernow_k6_verify(struct cpufreq_policy *policy)
{
      return cpufreq_frequency_table_verify(policy, &clock_ratio[0]);
}


/**
 * powernow_k6_setpolicy - sets a new CPUFreq policy
 * @policy: new policy
 * @target_freq: the target frequency
 * @relation: how that frequency relates to achieved frequency (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
 *
 * sets a new CPUFreq policy
 */
static int powernow_k6_target (struct cpufreq_policy *policy,
                         unsigned int target_freq,
                         unsigned int relation)
{
      unsigned int    newstate = 0;

      if (cpufreq_frequency_table_target(policy, &clock_ratio[0], target_freq, relation, &newstate))
            return -EINVAL;

      powernow_k6_set_state(newstate);

      return 0;
}


static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
{
      unsigned int i;
      int result;

      if (policy->cpu != 0)
            return -ENODEV;

      /* get frequencies */
      max_multiplier = powernow_k6_get_cpu_multiplier();
      busfreq = cpu_khz / max_multiplier;

      /* table init */
      for (i=0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
            if (clock_ratio[i].index > max_multiplier)
                  clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
            else
                  clock_ratio[i].frequency = busfreq * clock_ratio[i].index;
      }

      /* cpuinfo and default policy values */
      policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
      policy->cur = busfreq * max_multiplier;

      result = cpufreq_frequency_table_cpuinfo(policy, clock_ratio);
      if (result)
            return (result);

      cpufreq_frequency_table_get_attr(clock_ratio, policy->cpu);

      return 0;
}


static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
{
      unsigned int i;
      for (i=0; i<8; i++) {
            if (i==max_multiplier)
                  powernow_k6_set_state(i);
      }
      cpufreq_frequency_table_put_attr(policy->cpu);
      return 0;
}

static unsigned int powernow_k6_get(unsigned int cpu)
{
      return busfreq * powernow_k6_get_cpu_multiplier();
}

static struct freq_attr* powernow_k6_attr[] = {
      &cpufreq_freq_attr_scaling_available_freqs,
      NULL,
};

static struct cpufreq_driver powernow_k6_driver = {
      .verify           = powernow_k6_verify,
      .target           = powernow_k6_target,
      .init       = powernow_k6_cpu_init,
      .exit       = powernow_k6_cpu_exit,
      .get        = powernow_k6_get,
      .name       = "powernow-k6",
      .owner            = THIS_MODULE,
      .attr       = powernow_k6_attr,
};


/**
 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
 *
 *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
 * on success.
 */
static int __init powernow_k6_init(void)
{
      struct cpuinfo_x86 *c = &cpu_data(0);

      if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 5) ||
            ((c->x86_model != 12) && (c->x86_model != 13)))
            return -ENODEV;

      if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
            printk("cpufreq: PowerNow IOPORT region already used.\n");
            return -EIO;
      }

      if (cpufreq_register_driver(&powernow_k6_driver)) {
            release_region (POWERNOW_IOPORT, 16);
            return -EINVAL;
      }

      return 0;
}


/**
 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
 *
 *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
 */
static void __exit powernow_k6_exit(void)
{
      cpufreq_unregister_driver(&powernow_k6_driver);
      release_region (POWERNOW_IOPORT, 16);
}


MODULE_AUTHOR ("Arjan van de Ven <arjanv@redhat.com>, Dave Jones <davej@codemonkey.org.uk>, Dominik Brodowski <linux@brodo.de>");
MODULE_DESCRIPTION ("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
MODULE_LICENSE ("GPL");

module_init(powernow_k6_init);
module_exit(powernow_k6_exit);

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