powernow-k6.c

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/*
 *  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/timex.h>
#include <linux/io.h>

#include <asm/cpu_device_id.h>
#include <asm/msr.h>

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

#define PFX "powernow-k6: "
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}
};


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;
}


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 PFX "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;
}


static int powernow_k6_verify(struct cpufreq_policy *policy)
{
    return cpufreq_frequency_table_verify(policy, &clock_ratio[0]);
}


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, f;
    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++) {
        f = clock_ratio[i].index;
        if (f > max_multiplier)
            clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
        else
            clock_ratio[i].frequency = busfreq * f;
    }

    /* cpuinfo and default policy values */
    policy->cpuinfo.transition_latency = 200000;
    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)
{
    unsigned int ret;
    ret = (busfreq * powernow_k6_get_cpu_multiplier());
    return ret;
}

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,
};

static const struct x86_cpu_id powernow_k6_ids[] = {
    { X86_VENDOR_AMD, 5, 12 },
    { X86_VENDOR_AMD, 5, 13 },
    {}
};
MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);

static int __init powernow_k6_init(void)
{
    if (!x86_match_cpu(powernow_k6_ids))
        return -ENODEV;

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

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

    return 0;
}


static void __exit powernow_k6_exit(void)
{
    cpufreq_unregister_driver(&powernow_k6_driver);
    release_region(POWERNOW_IOPORT, 16);
}


MODULE_AUTHOR("Arjan van de Ven, Dave Jones <[email protected]>, "
        "Dominik Brodowski <[email protected]>");
MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
MODULE_LICENSE("GPL");

module_init(powernow_k6_init);
module_exit(powernow_k6_exit);