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/*
 * Intel SpeedStep SMI driver.
 *
 * (C) 2003  Hiroshi Miura <miura@da-cha.org>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *
 */


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

#include <linuxcomp.h>

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <asm/ist.h>

#include "speedstep-lib.h"

#define PFX "speedstep-smi: "

/* 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        = 0;
static int              smi_cmd         = 0;
static unsigned int     smi_sig         = 0;


/*
 *   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

/* DEBUG
 *   Define it if you want verbose debug output, e.g. for bug reporting
 */
#define SPEEDSTEP_DEBUG

#ifdef SPEEDSTEP_DEBUG
#define dprintk(msg...) printk(msg)
#else
#define dprintk(msg...) do { } while(0)
#endif

/**
 * speedstep_smi_ownership
 */
static int speedstep_smi_ownership (void)
{
        u32 command, result, magic;
        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);

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

        return result;
}

/**
 * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
 *
 */
static int speedstep_smi_get_freqs (unsigned int *low, unsigned int *high)
{
        u32 command, result, edi, high_mhz, low_mhz;
        u32 state=0;
        u32 function = GET_SPEEDSTEP_FREQS;

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

        __asm__ __volatile__("movl $0, %%edi\n"
                "out %%al, (%%dx)\n"
                : "=a" (result), "=b" (high_mhz), "=c" (low_mhz), "=d" (state), "=D" (edi)
                : "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
        );
        *high = high_mhz * 1000;
        *low  = low_mhz  * 1000;

        return result;
}

/**
 * speedstep_get_state - set the SpeedStep state
 * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 *
 */
static int speedstep_get_state (void)
{
        u32 function=GET_SPEEDSTEP_STATE;
        u32 result, state, edi, command;

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

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

        return state;
}

/**
 * speedstep_set_state - set the SpeedStep state
 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 *
 */
static void speedstep_set_state (unsigned int state, unsigned int notify)
{
        unsigned int old_state, result, command, new_state;
        unsigned long flags;
        struct cpufreq_freqs freqs;
        unsigned int function=SET_SPEEDSTEP_STATE;

        if (state > 0x1)
                return;

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

        if (old_state == state)
                return;

        if (notify)
                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

        /* Disable IRQs */
        local_irq_save(flags);

        command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
        __asm__ __volatile__(
                "movl $0, %%edi\n"
                "out %%al, (%%dx)\n"
                : "=b" (new_state), "=D" (result)
                : "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
        );

        /* enable IRQs */
        local_irq_restore(flags);

        if (new_state == state) {
                dprintk(KERN_INFO "cpufreq: change to %u MHz succeded\n", (freqs.new / 1000));
        } else {
                printk(KERN_ERR "cpufreq: change failed\n");
        }

        if (notify)
                cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

        return;
}


/**
 * speedstep_target - set a new CPUFreq policy
 * @policy: new policy
 * @target_freq: new freq
 * @relation:
 *
 * Sets a new CPUFreq policy/freq.
 */
static int speedstep_target (struct cpufreq_policy *policy,
                        unsigned int target_freq, unsigned int relation)
{
        unsigned int newstate = 0;

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

        speedstep_set_state(newstate, 1);

        return 0;
}


/**
 * speedstep_verify - verifies a new CPUFreq policy
 * @freq: new policy
 *
 * Limit must be within speedstep_low_freq and speedstep_high_freq, with
 * at least one border included.
 */
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;

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

        result = speedstep_smi_ownership();

        if (result)
                dprintk(KERN_INFO "cpufreq: fails an aquiring ownership of a SMI interface.\n");

        /* detect low and high frequency */
        result = speedstep_smi_get_freqs(&speedstep_freqs[SPEEDSTEP_LOW].frequency,
                                &speedstep_freqs[SPEEDSTEP_HIGH].frequency);
        if (result) {
                /* fall back to speedstep_lib.c dection mechanism: try both states out */
                unsigned int speedstep_processor = speedstep_detect_processor();

                dprintk(KERN_INFO PFX "could not detect low and high frequencies by SMI call.\n");
                if (!speedstep_processor)
                        return -ENODEV;

                result = speedstep_get_freqs(speedstep_processor,
                                &speedstep_freqs[SPEEDSTEP_LOW].frequency,
                                &speedstep_freqs[SPEEDSTEP_HIGH].frequency,
                                &speedstep_set_state);

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

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

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

        /* cpuinfo and default policy values */
        policy->governor = 0; //!!!CPUFREQ_DEFAULT_GOVERNOR;
        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
        policy->cur = speed;

        return cpufreq_frequency_table_cpuinfo(policy, &speedstep_freqs[0]);
}


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

        if (result)
                dprintk(KERN_INFO "cpufreq: fails an aquiring ownership of a SMI interface.\n");

        return result;
}


static struct cpufreq_driver speedstep_driver = {
        .name           = "speedstep-smi",
        .verify         = speedstep_verify,
        .target         = speedstep_target,
        .init           = speedstep_cpu_init,
        .resume         = speedstep_resume,
};

/**
 * speedstep_init - initializes the SpeedStep CPUFreq driver
 *
 *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 * BIOS, -EINVAL on problems during initiatization, and zero on
 * success.
 */
/*static*/ int __init speedstep_smi_init(void)
{
        struct cpuinfo_x86 *c = &new_cpu_data;

        if (c->x86_vendor != X86_VENDOR_INTEL) {
                dprintk (KERN_INFO PFX "No Intel CPU detected.\n");
                return -ENODEV;
        }

        dprintk(KERN_DEBUG PFX "signature:0x%.8lx, command:0x%.8lx, event:0x%.8lx, perf_level:0x%.8lx.\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);
}


/**
 * speedstep_exit - unregisters SpeedStep support
 *
 *   Unregisters SpeedStep support.
 */
/*static*/ void __exit speedstep_smi_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_smi_init);
module_exit(speedstep_smi_exit);