speedstep-smi.c

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/*
 * Intel SpeedStep SMI driver.
 *
 * (C) 2003  Hiroshi Miura <[email protected]>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *
 */


/*********************************************************************
 *                        SPEEDSTEP - DEFINITIONS                    *
 *********************************************************************/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <asm/ist.h>
#include <asm/cpu_device_id.h>

#include "speedstep-lib.h"

/* speedstep system management interface port/command.
 *
 * These parameters are got from IST-SMI BIOS call.
 * If user gives it, these are used.
 *
 */
static int smi_port;
static int smi_cmd;
static unsigned int smi_sig;

/* info about the processor */
static enum speedstep_processor speedstep_processor;

/*
 * There are only two frequency states for each processor. Values
 * are in kHz for the time being.
 */
static struct cpufreq_frequency_table speedstep_freqs[] = {
    {SPEEDSTEP_HIGH,    0},
    {SPEEDSTEP_LOW,     0},
    {0,         CPUFREQ_TABLE_END},
};

#define GET_SPEEDSTEP_OWNER 0
#define GET_SPEEDSTEP_STATE 1
#define SET_SPEEDSTEP_STATE 2
#define GET_SPEEDSTEP_FREQS 4

/* how often shall the SMI call be tried if it failed, e.g. because
 * of DMA activity going on? */
#define SMI_TRIES 5

static int speedstep_smi_ownership(void)
{
    u32 command, result, magic, dummy;
    u32 function = GET_SPEEDSTEP_OWNER;
    unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";

    command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
    magic = virt_to_phys(magic_data);

    pr_debug("trying to obtain ownership with command %x at port %x\n",
            command, smi_port);

    __asm__ __volatile__(
        "push %%ebp\n"
        "out %%al, (%%dx)\n"
        "pop %%ebp\n"
        : "=D" (result),
          "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
          "=S" (dummy)
        : "a" (command), "b" (function), "c" (0), "d" (smi_port),
          "D" (0), "S" (magic)
        : "memory"
    );

    pr_debug("result is %x\n", result);

    return result;
}

static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
{
    u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
    u32 state = 0;
    u32 function = GET_SPEEDSTEP_FREQS;

    if (!(ist_info.event & 0xFFFF)) {
        pr_debug("bug #1422 -- can't read freqs from BIOS\n");
        return -ENODEV;
    }

    command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);

    pr_debug("trying to determine frequencies with command %x at port %x\n",
            command, smi_port);

    __asm__ __volatile__(
        "push %%ebp\n"
        "out %%al, (%%dx)\n"
        "pop %%ebp"
        : "=a" (result),
          "=b" (high_mhz),
          "=c" (low_mhz),
          "=d" (state), "=D" (edi), "=S" (dummy)
        : "a" (command),
          "b" (function),
          "c" (state),
          "d" (smi_port), "S" (0), "D" (0)
    );

    pr_debug("result %x, low_freq %u, high_freq %u\n",
            result, low_mhz, high_mhz);

    /* abort if results are obviously incorrect... */
    if ((high_mhz + low_mhz) < 600)
        return -EINVAL;

    *high = high_mhz * 1000;
    *low  = low_mhz  * 1000;

    return result;
}

static int speedstep_get_state(void)
{
    u32 function = GET_SPEEDSTEP_STATE;
    u32 result, state, edi, command, dummy;

    command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);

    pr_debug("trying to determine current setting with command %x "
        "at port %x\n", command, smi_port);

    __asm__ __volatile__(
        "push %%ebp\n"
        "out %%al, (%%dx)\n"
        "pop %%ebp\n"
        : "=a" (result),
          "=b" (state), "=D" (edi),
          "=c" (dummy), "=d" (dummy), "=S" (dummy)
        : "a" (command), "b" (function), "c" (0),
          "d" (smi_port), "S" (0), "D" (0)
    );

    pr_debug("state is %x, result is %x\n", state, result);

    return state & 1;
}


static void speedstep_set_state(unsigned int state)
{
    unsigned int result = 0, command, new_state, dummy;
    unsigned long flags;
    unsigned int function = SET_SPEEDSTEP_STATE;
    unsigned int retry = 0;

    if (state > 0x1)
        return;

    /* Disable IRQs */
    local_irq_save(flags);

    command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);

    pr_debug("trying to set frequency to state %u "
        "with command %x at port %x\n",
        state, command, smi_port);

    do {
        if (retry) {
            pr_debug("retry %u, previous result %u, waiting...\n",
                    retry, result);
            mdelay(retry * 50);
        }
        retry++;
        __asm__ __volatile__(
            "push %%ebp\n"
            "out %%al, (%%dx)\n"
            "pop %%ebp"
            : "=b" (new_state), "=D" (result),
              "=c" (dummy), "=a" (dummy),
              "=d" (dummy), "=S" (dummy)
            : "a" (command), "b" (function), "c" (state),
              "d" (smi_port), "S" (0), "D" (0)
            );
    } while ((new_state != state) && (retry <= SMI_TRIES));

    /* enable IRQs */
    local_irq_restore(flags);

    if (new_state == state)
        pr_debug("change to %u MHz succeeded after %u tries "
            "with result %u\n",
            (speedstep_freqs[new_state].frequency / 1000),
            retry, result);
    else
        printk(KERN_ERR "cpufreq: change to state %u "
            "failed with new_state %u and result %u\n",
            state, new_state, result);

    return;
}


static int speedstep_target(struct cpufreq_policy *policy,
            unsigned int target_freq, unsigned int relation)
{
    unsigned int newstate = 0;
    struct cpufreq_freqs freqs;

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

    freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
    freqs.new = speedstep_freqs[newstate].frequency;
    freqs.cpu = 0; /* speedstep.c is UP only driver */

    if (freqs.old == freqs.new)
        return 0;

    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
    speedstep_set_state(newstate);
    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

    return 0;
}


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


static int speedstep_cpu_init(struct cpufreq_policy *policy)
{
    int result;
    unsigned int speed, state;
    unsigned int *low, *high;

    /* capability check */
    if (policy->cpu != 0)
        return -ENODEV;

    result = speedstep_smi_ownership();
    if (result) {
        pr_debug("fails in acquiring ownership of a SMI interface.\n");
        return -EINVAL;
    }

    /* detect low and high frequency */
    low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
    high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;

    result = speedstep_smi_get_freqs(low, high);
    if (result) {
        /* fall back to speedstep_lib.c dection mechanism:
         * try both states out */
        pr_debug("could not detect low and high frequencies "
                "by SMI call.\n");
        result = speedstep_get_freqs(speedstep_processor,
                low, high,
                NULL,
                &speedstep_set_state);

        if (result) {
            pr_debug("could not detect two different speeds"
                    " -- aborting.\n");
            return result;
        } else
            pr_debug("workaround worked.\n");
    }

    /* get current speed setting */
    state = speedstep_get_state();
    speed = speedstep_freqs[state].frequency;

    pr_debug("currently at %s speed setting - %i MHz\n",
        (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
        ? "low" : "high",
        (speed / 1000));

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

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

    cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);

    return 0;
}

static int speedstep_cpu_exit(struct cpufreq_policy *policy)
{
    cpufreq_frequency_table_put_attr(policy->cpu);
    return 0;
}

static unsigned int speedstep_get(unsigned int cpu)
{
    if (cpu)
        return -ENODEV;
    return speedstep_get_frequency(speedstep_processor);
}


static int speedstep_resume(struct cpufreq_policy *policy)
{
    int result = speedstep_smi_ownership();

    if (result)
        pr_debug("fails in re-acquiring ownership of a SMI interface.\n");

    return result;
}

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

static struct cpufreq_driver speedstep_driver = {
    .name       = "speedstep-smi",
    .verify     = speedstep_verify,
    .target     = speedstep_target,
    .init       = speedstep_cpu_init,
    .exit       = speedstep_cpu_exit,
    .get        = speedstep_get,
    .resume     = speedstep_resume,
    .owner      = THIS_MODULE,
    .attr       = speedstep_attr,
};

static const struct x86_cpu_id ss_smi_ids[] = {
    { X86_VENDOR_INTEL, 6, 0xb, },
    { X86_VENDOR_INTEL, 6, 0x8, },
    { X86_VENDOR_INTEL, 15, 2 },
    {}
};
#if 0
/* Not auto loaded currently */
MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
#endif

static int __init speedstep_init(void)
{
    if (!x86_match_cpu(ss_smi_ids))
        return -ENODEV;

    speedstep_processor = speedstep_detect_processor();

    switch (speedstep_processor) {
    case SPEEDSTEP_CPU_PIII_T:
    case SPEEDSTEP_CPU_PIII_C:
    case SPEEDSTEP_CPU_PIII_C_EARLY:
        break;
    default:
        speedstep_processor = 0;
    }

    if (!speedstep_processor) {
        pr_debug("No supported Intel CPU detected.\n");
        return -ENODEV;
    }

    pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
        "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
        ist_info.signature, ist_info.command,
        ist_info.event, ist_info.perf_level);

    /* Error if no IST-SMI BIOS or no PARM
         sig= 'ISGE' aka 'Intel Speedstep Gate E' */
    if ((ist_info.signature !=  0x47534943) && (
        (smi_port == 0) || (smi_cmd == 0)))
        return -ENODEV;

    if (smi_sig == 1)
        smi_sig = 0x47534943;
    else
        smi_sig = ist_info.signature;

    /* setup smi_port from MODLULE_PARM or BIOS */
    if ((smi_port > 0xff) || (smi_port < 0))
        return -EINVAL;
    else if (smi_port == 0)
        smi_port = ist_info.command & 0xff;

    if ((smi_cmd > 0xff) || (smi_cmd < 0))
        return -EINVAL;
    else if (smi_cmd == 0)
        smi_cmd = (ist_info.command >> 16) & 0xff;

    return cpufreq_register_driver(&speedstep_driver);
}


static void __exit speedstep_exit(void)
{
    cpufreq_unregister_driver(&speedstep_driver);
}

module_param(smi_port, int, 0444);
module_param(smi_cmd,  int, 0444);
module_param(smi_sig, uint, 0444);

MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
        "-- Intel's default setting is 0xb2");
MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
        "-- Intel's default setting is 0x82");
MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
        "SMI interface.");

MODULE_AUTHOR("Hiroshi Miura");
MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
MODULE_LICENSE("GPL");

module_init(speedstep_init);
module_exit(speedstep_exit);