[CPUFREQ] Advise not to use longhaul on VIA C7.

[linux-2.6.22.y-op.git] / arch / i386 / kernel / cpu / cpufreq / longhaul.c

/*
 *  (C) 2001-2004  Dave Jones. <davej@codemonkey.org.uk>
 *  (C) 2002  Padraig Brady. <padraig@antefacto.com>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *  Based upon datasheets & sample CPUs kindly provided by VIA.
 *
 *  VIA have currently 3 different versions of Longhaul.
 *  Version 1 (Longhaul) uses the BCR2 MSR at 0x1147.
 *   It is present only in Samuel 1 (C5A), Samuel 2 (C5B) stepping 0.
 *  Version 2 of longhaul is the same as v1, but adds voltage scaling.
 *   Present in Samuel 2 (steppings 1-7 only) (C5B), and Ezra (C5C)
 *   voltage scaling support has currently been disabled in this driver
 *   until we have code that gets it right.
 *  Version 3 of longhaul got renamed to Powersaver and redesigned
 *   to use the POWERSAVER MSR at 0x110a.
 *   It is present in Ezra-T (C5M), Nehemiah (C5X) and above.
 *   It's pretty much the same feature wise to longhaul v2, though
 *   there is provision for scaling FSB too, but this doesn't work
 *   too well in practice so we don't even try to use this.
 *
 *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
 */

#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 <linux/string.h>

#include <asm/msr.h>
#include <asm/timex.h>
#include <asm/io.h>
#include <asm/acpi.h>
#include <linux/acpi.h>
#include <acpi/processor.h>

#include "longhaul.h"

#define PFX "longhaul: "

#define TYPE_LONGHAUL_V1        1
#define TYPE_LONGHAUL_V2        2
#define TYPE_POWERSAVER         3

#define CPU_SAMUEL      1
#define CPU_SAMUEL2     2
#define CPU_EZRA        3
#define CPU_EZRA_T      4
#define CPU_NEHEMIAH    5

static int cpu_model;
static unsigned int numscales=16;
static unsigned int fsb;

static struct mV_pos *vrm_mV_table;
static unsigned char *mV_vrm_table;
struct f_msr {
        unsigned char vrm;
};
static struct f_msr f_msr_table[32];

static unsigned int highest_speed, lowest_speed; /* kHz */
static unsigned int minmult, maxmult;
static int can_scale_voltage;
static struct acpi_processor *pr = NULL;
static struct acpi_processor_cx *cx = NULL;
static int port22_en;

/* Module parameters */
static int scale_voltage;
static int ignore_latency;

#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "longhaul", msg)


/* Clock ratios multiplied by 10 */
static int clock_ratio[32];
static int eblcr_table[32];
static unsigned int highest_speed, lowest_speed; /* kHz */
static int longhaul_version;
static struct cpufreq_frequency_table *longhaul_table;

#ifdef CONFIG_CPU_FREQ_DEBUG
static char speedbuffer[8];

static char *print_speed(int speed)
{
        if (speed < 1000) {
                snprintf(speedbuffer, sizeof(speedbuffer),"%dMHz", speed);
                return speedbuffer;
        }

        if (speed%1000 == 0)
                snprintf(speedbuffer, sizeof(speedbuffer),
                        "%dGHz", speed/1000);
        else
                snprintf(speedbuffer, sizeof(speedbuffer),
                        "%d.%dGHz", speed/1000, (speed%1000)/100);

        return speedbuffer;
}
#endif


static unsigned int calc_speed(int mult)
{
        int khz;
        khz = (mult/10)*fsb;
        if (mult%10)
                khz += fsb/2;
        khz *= 1000;
        return khz;
}


static int longhaul_get_cpu_mult(void)
{
        unsigned long invalue=0,lo, hi;

        rdmsr (MSR_IA32_EBL_CR_POWERON, lo, hi);
        invalue = (lo & (1<<22|1<<23|1<<24|1<<25)) >>22;
        if (longhaul_version==TYPE_LONGHAUL_V2 || longhaul_version==TYPE_POWERSAVER) {
                if (lo & (1<<27))
                        invalue+=16;
        }
        return eblcr_table[invalue];
}

/* For processor with BCR2 MSR */

static void do_longhaul1(unsigned int clock_ratio_index)
{
        union msr_bcr2 bcr2;

        rdmsrl(MSR_VIA_BCR2, bcr2.val);
        /* Enable software clock multiplier */
        bcr2.bits.ESOFTBF = 1;
        bcr2.bits.CLOCKMUL = clock_ratio_index;

        /* Sync to timer tick */
        safe_halt();
        /* Change frequency on next halt or sleep */
        wrmsrl(MSR_VIA_BCR2, bcr2.val);
        /* Invoke transition */
        ACPI_FLUSH_CPU_CACHE();
        halt();

        /* Disable software clock multiplier */
        local_irq_disable();
        rdmsrl(MSR_VIA_BCR2, bcr2.val);
        bcr2.bits.ESOFTBF = 0;
        wrmsrl(MSR_VIA_BCR2, bcr2.val);
}

/* For processor with Longhaul MSR */

static void do_powersaver(int cx_address, unsigned int clock_ratio_index)
{
        union msr_longhaul longhaul;
        u32 t;

        rdmsrl(MSR_VIA_LONGHAUL, longhaul.val);
        longhaul.bits.RevisionKey = longhaul.bits.RevisionID;
        longhaul.bits.SoftBusRatio = clock_ratio_index & 0xf;
        longhaul.bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
        longhaul.bits.EnableSoftBusRatio = 1;

        if (can_scale_voltage) {
                longhaul.bits.SoftVID = f_msr_table[clock_ratio_index].vrm;
                longhaul.bits.EnableSoftVID = 1;
        }

        /* Sync to timer tick */
        safe_halt();
        /* Change frequency on next halt or sleep */
        wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
        if (port22_en) {
                ACPI_FLUSH_CPU_CACHE();
                /* Invoke C1 */
                halt();
        } else {
                ACPI_FLUSH_CPU_CACHE();
                /* Invoke C3 */
                inb(cx_address);
                /* Dummy op - must do something useless after P_LVL3 read */
                t = inl(acpi_fadt.xpm_tmr_blk.address);
        }

        /* Disable bus ratio bit */
        local_irq_disable();
        longhaul.bits.RevisionKey = longhaul.bits.RevisionID;
        longhaul.bits.EnableSoftBusRatio = 0;
        longhaul.bits.EnableSoftBSEL = 0;
        longhaul.bits.EnableSoftVID = 0;
        wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
}

/**
 * longhaul_set_cpu_frequency()
 * @clock_ratio_index : bitpattern of the new multiplier.
 *
 * Sets a new clock ratio.
 */

static void longhaul_setstate(unsigned int clock_ratio_index)
{
        int speed, mult;
        struct cpufreq_freqs freqs;
        static unsigned int old_ratio=-1;
        unsigned long flags;
        unsigned int pic1_mask, pic2_mask;

        if (old_ratio == clock_ratio_index)
                return;
        old_ratio = clock_ratio_index;

        mult = clock_ratio[clock_ratio_index];
        if (mult == -1)
                return;

        speed = calc_speed(mult);
        if ((speed > highest_speed) || (speed < lowest_speed))
                return;

        freqs.old = calc_speed(longhaul_get_cpu_mult());
        freqs.new = speed;
        freqs.cpu = 0; /* longhaul.c is UP only driver */

        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

        dprintk ("Setting to FSB:%dMHz Mult:%d.%dx (%s)\n",
                        fsb, mult/10, mult%10, print_speed(speed/1000));

        preempt_disable();
        local_irq_save(flags);

        pic2_mask = inb(0xA1);
        pic1_mask = inb(0x21);  /* works on C3. save mask. */
        outb(0xFF,0xA1);        /* Overkill */
        outb(0xFE,0x21);        /* TMR0 only */

        if (pr->flags.bm_control) {
                /* Disable bus master arbitration */
                acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1,
                                  ACPI_MTX_DO_NOT_LOCK);
        } else if (port22_en) {
                /* Disable AGP and PCI arbiters */
                outb(3, 0x22);
        }

        switch (longhaul_version) {

        /*
         * Longhaul v1. (Samuel[C5A] and Samuel2 stepping 0[C5B])
         * Software controlled multipliers only.
         *
         * *NB* Until we get voltage scaling working v1 & v2 are the same code.
         * Longhaul v2 appears in Samuel2 Steppings 1->7 [C5b] and Ezra [C5C]
         */
        case TYPE_LONGHAUL_V1:
        case TYPE_LONGHAUL_V2:
                do_longhaul1(clock_ratio_index);
                break;

        /*
         * Longhaul v3 (aka Powersaver). (Ezra-T [C5M] & Nehemiah [C5N])
         * We can scale voltage with this too, but that's currently
         * disabled until we come up with a decent 'match freq to voltage'
         * algorithm.
         * When we add voltage scaling, we will also need to do the
         * voltage/freq setting in order depending on the direction
         * of scaling (like we do in powernow-k7.c)
         * Nehemiah can do FSB scaling too, but this has never been proven
         * to work in practice.
         */
        case TYPE_POWERSAVER:
                /* Don't allow wakeup */
                acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0,
                                  ACPI_MTX_DO_NOT_LOCK);
                do_powersaver(cx->address, clock_ratio_index);
                break;
        }

        if (pr->flags.bm_control) {
                /* Enable bus master arbitration */
                acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0,
                                  ACPI_MTX_DO_NOT_LOCK);
        } else if (port22_en) {
                /* Enable arbiters */
                outb(0, 0x22);
        }

        outb(pic2_mask,0xA1);   /* restore mask */
        outb(pic1_mask,0x21);

        local_irq_restore(flags);
        preempt_enable();

        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
}

/*
 * Centaur decided to make life a little more tricky.
 * Only longhaul v1 is allowed to read EBLCR BSEL[0:1].
 * Samuel2 and above have to try and guess what the FSB is.
 * We do this by assuming we booted at maximum multiplier, and interpolate
 * between that value multiplied by possible FSBs and cpu_mhz which
 * was calculated at boot time. Really ugly, but no other way to do this.
 */

#define ROUNDING        0xf

static int _guess(int guess)
{
        int target;

        target = ((maxmult/10)*guess);
        if (maxmult%10 != 0)
                target += (guess/2);
        target += ROUNDING/2;
        target &= ~ROUNDING;
        return target;
}


static int guess_fsb(void)
{
        int speed = (cpu_khz/1000);
        int i;
        int speeds[3] = { 66, 100, 133 };

        speed += ROUNDING/2;
        speed &= ~ROUNDING;

        for (i=0; i<3; i++) {
                if (_guess(speeds[i]) == speed)
                        return speeds[i];
        }
        return 0;
}


static int __init longhaul_get_ranges(void)
{
        unsigned long invalue;
        unsigned int ezra_t_multipliers[32]= {
                        90,  30,  40, 100,  55,  35,  45,  95,
                        50,  70,  80,  60, 120,  75,  85,  65,
                        -1, 110, 120,  -1, 135, 115, 125, 105,
                        130, 150, 160, 140,  -1, 155,  -1, 145 };
        unsigned int j, k = 0;
        union msr_longhaul longhaul;
        unsigned long lo, hi;
        unsigned int eblcr_fsb_table_v1[] = { 66, 133, 100, -1 };
        unsigned int eblcr_fsb_table_v2[] = { 133, 100, -1, 66 };

        switch (longhaul_version) {
        case TYPE_LONGHAUL_V1:
        case TYPE_LONGHAUL_V2:
                /* Ugh, Longhaul v1 didn't have the min/max MSRs.
                   Assume min=3.0x & max = whatever we booted at. */
                minmult = 30;
                maxmult = longhaul_get_cpu_mult();
                rdmsr (MSR_IA32_EBL_CR_POWERON, lo, hi);
                invalue = (lo & (1<<18|1<<19)) >>18;
                if (cpu_model==CPU_SAMUEL || cpu_model==CPU_SAMUEL2)
                        fsb = eblcr_fsb_table_v1[invalue];
                else
                        fsb = guess_fsb();
                break;

        case TYPE_POWERSAVER:
                /* Ezra-T */
                if (cpu_model==CPU_EZRA_T) {
                        rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
                        invalue = longhaul.bits.MaxMHzBR;
                        if (longhaul.bits.MaxMHzBR4)
                                invalue += 16;
                        maxmult=ezra_t_multipliers[invalue];

                        invalue = longhaul.bits.MinMHzBR;
                        if (longhaul.bits.MinMHzBR4 == 1)
                                minmult = 30;
                        else
                                minmult = ezra_t_multipliers[invalue];
                        fsb = eblcr_fsb_table_v2[longhaul.bits.MaxMHzFSB];
                        break;
                }

                /* Nehemiah */
                if (cpu_model==CPU_NEHEMIAH) {
                        rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);

                        /*
                         * TODO: This code works, but raises a lot of questions.
                         * - Some Nehemiah's seem to have broken Min/MaxMHzBR's.
                         *   We get around this by using a hardcoded multiplier of 4.0x
                         *   for the minimimum speed, and the speed we booted up at for the max.
                         *   This is done in longhaul_get_cpu_mult() by reading the EBLCR register.
                         * - According to some VIA documentation EBLCR is only
                         *   in pre-Nehemiah C3s. How this still works is a mystery.
                         *   We're possibly using something undocumented and unsupported,
                         *   But it works, so we don't grumble.
                         */
                        minmult=40;
                        maxmult=longhaul_get_cpu_mult();

                        /* Starting with the 1.2GHz parts, theres a 200MHz bus. */
                        if ((cpu_khz/maxmult) > 13400)
                                fsb = 200;
                        else
                                fsb = eblcr_fsb_table_v2[longhaul.bits.MaxMHzFSB];
                        break;
                }
        }

        dprintk ("MinMult:%d.%dx MaxMult:%d.%dx\n",
                 minmult/10, minmult%10, maxmult/10, maxmult%10);

        if (fsb == -1) {
                printk (KERN_INFO PFX "Invalid (reserved) FSB!\n");
                return -EINVAL;
        }

        highest_speed = calc_speed(maxmult);
        lowest_speed = calc_speed(minmult);
        dprintk ("FSB:%dMHz  Lowest speed: %s   Highest speed:%s\n", fsb,
                 print_speed(lowest_speed/1000), 
                 print_speed(highest_speed/1000));

        if (lowest_speed == highest_speed) {
                printk (KERN_INFO PFX "highestspeed == lowest, aborting.\n");
                return -EINVAL;
        }
        if (lowest_speed > highest_speed) {
                printk (KERN_INFO PFX "nonsense! lowest (%d > %d) !\n",
                        lowest_speed, highest_speed);
                return -EINVAL;
        }

        longhaul_table = kmalloc((numscales + 1) * sizeof(struct cpufreq_frequency_table), GFP_KERNEL);
        if(!longhaul_table)
                return -ENOMEM;

        for (j=0; j < numscales; j++) {
                unsigned int ratio;
                ratio = clock_ratio[j];
                if (ratio == -1)
                        continue;
                if (ratio > maxmult || ratio < minmult)
                        continue;
                longhaul_table[k].frequency = calc_speed(ratio);
                longhaul_table[k].index = j;
                k++;
        }

        longhaul_table[k].frequency = CPUFREQ_TABLE_END;
        if (!k) {
                kfree (longhaul_table);
                return -EINVAL;
        }

        return 0;
}


static void __init longhaul_setup_voltagescaling(void)
{
        union msr_longhaul longhaul;
        struct mV_pos minvid, maxvid;
        unsigned int j, speed, pos, kHz_step, numvscales;

        rdmsrl(MSR_VIA_LONGHAUL, longhaul.val);
        if (!(longhaul.bits.RevisionID & 1)) {
                printk(KERN_INFO PFX "Voltage scaling not supported by CPU.\n");
                return;
        }

        if (!longhaul.bits.VRMRev) {
                printk (KERN_INFO PFX "VRM 8.5\n");
                vrm_mV_table = &vrm85_mV[0];
                mV_vrm_table = &mV_vrm85[0];
        } else {
                printk (KERN_INFO PFX "Mobile VRM\n");
                vrm_mV_table = &mobilevrm_mV[0];
                mV_vrm_table = &mV_mobilevrm[0];
        }

        minvid = vrm_mV_table[longhaul.bits.MinimumVID];
        maxvid = vrm_mV_table[longhaul.bits.MaximumVID];
        numvscales = maxvid.pos - minvid.pos + 1;
        kHz_step = (highest_speed - lowest_speed) / numvscales;

        if (minvid.mV == 0 || maxvid.mV == 0 || minvid.mV > maxvid.mV) {
                printk (KERN_INFO PFX "Bogus values Min:%d.%03d Max:%d.%03d. "
                                        "Voltage scaling disabled.\n",
                                        minvid.mV/1000, minvid.mV%1000, maxvid.mV/1000, maxvid.mV%1000);
                return;
        }

        if (minvid.mV == maxvid.mV) {
                printk (KERN_INFO PFX "Claims to support voltage scaling but min & max are "
                                "both %d.%03d. Voltage scaling disabled\n",
                                maxvid.mV/1000, maxvid.mV%1000);
                return;
        }

        printk(KERN_INFO PFX "Max VID=%d.%03d  Min VID=%d.%03d, %d possible voltage scales\n",
                maxvid.mV/1000, maxvid.mV%1000,
                minvid.mV/1000, minvid.mV%1000,
                numvscales);
        
        j = 0;
        while (longhaul_table[j].frequency != CPUFREQ_TABLE_END) {
                speed = longhaul_table[j].frequency;
                pos = (speed - lowest_speed) / kHz_step + minvid.pos;
                f_msr_table[longhaul_table[j].index].vrm = mV_vrm_table[pos];
                j++;
        }

        can_scale_voltage = 1;
}


static int longhaul_verify(struct cpufreq_policy *policy)
{
        return cpufreq_frequency_table_verify(policy, longhaul_table);
}


static int longhaul_target(struct cpufreq_policy *policy,
                            unsigned int target_freq, unsigned int relation)
{
        unsigned int table_index = 0;
        unsigned int new_clock_ratio = 0;

        if (cpufreq_frequency_table_target(policy, longhaul_table, target_freq, relation, &table_index))
                return -EINVAL;

        new_clock_ratio = longhaul_table[table_index].index & 0xFF;

        longhaul_setstate(new_clock_ratio);

        return 0;
}


static unsigned int longhaul_get(unsigned int cpu)
{
        if (cpu)
                return 0;
        return calc_speed(longhaul_get_cpu_mult());
}

static acpi_status longhaul_walk_callback(acpi_handle obj_handle,
                                          u32 nesting_level,
                                          void *context, void **return_value)
{
        struct acpi_device *d;

        if ( acpi_bus_get_device(obj_handle, &d) ) {
                return 0;
        }
        *return_value = (void *)acpi_driver_data(d);
        return 1;
}

/* VIA don't support PM2 reg, but have something similar */
static int enable_arbiter_disable(void)
{
        struct pci_dev *dev;
        int reg;
        u8 pci_cmd;

        /* Find PLE133 host bridge */
        reg = 0x78;
        dev = pci_find_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8601_0, NULL);
        /* Find CLE266 host bridge */
        if (dev == NULL) {
                reg = 0x76;
                dev = pci_find_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_862X_0, NULL);
                /* Find CN400 V-Link host bridge */
                if (dev == NULL)
                        dev = pci_find_device(PCI_VENDOR_ID_VIA, 0x7259, NULL);

        }
        if (dev != NULL) {
                /* Enable access to port 0x22 */
                pci_read_config_byte(dev, reg, &pci_cmd);
                if ( !(pci_cmd & 1<<7) ) {
                        pci_cmd |= 1<<7;
                        pci_write_config_byte(dev, reg, pci_cmd);
                }
                return 1;
        }
        return 0;
}

static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
{
        struct cpuinfo_x86 *c = cpu_data;
        char *cpuname=NULL;
        int ret;

        /* Check what we have on this motherboard */
        switch (c->x86_model) {
        case 6:
                cpu_model = CPU_SAMUEL;
                cpuname = "C3 'Samuel' [C5A]";
                longhaul_version = TYPE_LONGHAUL_V1;
                memcpy (clock_ratio, samuel1_clock_ratio, sizeof(samuel1_clock_ratio));
                memcpy (eblcr_table, samuel1_eblcr, sizeof(samuel1_eblcr));
                break;

        case 7:
                longhaul_version = TYPE_LONGHAUL_V1;
                switch (c->x86_mask) {
                case 0:
                        cpu_model = CPU_SAMUEL2;
                        cpuname = "C3 'Samuel 2' [C5B]";
                        /* Note, this is not a typo, early Samuel2's had Samuel1 ratios. */
                        memcpy (clock_ratio, samuel1_clock_ratio, sizeof(samuel1_clock_ratio));
                        memcpy (eblcr_table, samuel2_eblcr, sizeof(samuel2_eblcr));
                        break;
                case 1 ... 15:
                        if (c->x86_mask < 8) {
                                cpu_model = CPU_SAMUEL2;
                                cpuname = "C3 'Samuel 2' [C5B]";
                        } else {
                                cpu_model = CPU_EZRA;
                                cpuname = "C3 'Ezra' [C5C]";
                        }
                        memcpy (clock_ratio, ezra_clock_ratio, sizeof(ezra_clock_ratio));
                        memcpy (eblcr_table, ezra_eblcr, sizeof(ezra_eblcr));
                        break;
                }
                break;

        case 8:
                cpu_model = CPU_EZRA_T;
                cpuname = "C3 'Ezra-T' [C5M]";
                longhaul_version = TYPE_POWERSAVER;
                numscales=32;
                memcpy (clock_ratio, ezrat_clock_ratio, sizeof(ezrat_clock_ratio));
                memcpy (eblcr_table, ezrat_eblcr, sizeof(ezrat_eblcr));
                break;

        case 9:
                cpu_model = CPU_NEHEMIAH;
                longhaul_version = TYPE_POWERSAVER;
                numscales=32;
                switch (c->x86_mask) {
                case 0 ... 1:
                        cpuname = "C3 'Nehemiah A' [C5N]";
                        memcpy (clock_ratio, nehemiah_a_clock_ratio, sizeof(nehemiah_a_clock_ratio));
                        memcpy (eblcr_table, nehemiah_a_eblcr, sizeof(nehemiah_a_eblcr));
                        break;
                case 2 ... 4:
                        cpuname = "C3 'Nehemiah B' [C5N]";
                        memcpy (clock_ratio, nehemiah_b_clock_ratio, sizeof(nehemiah_b_clock_ratio));
                        memcpy (eblcr_table, nehemiah_b_eblcr, sizeof(nehemiah_b_eblcr));
                        break;
                case 5 ... 15:
                        cpuname = "C3 'Nehemiah C' [C5N]";
                        memcpy (clock_ratio, nehemiah_c_clock_ratio, sizeof(nehemiah_c_clock_ratio));
                        memcpy (eblcr_table, nehemiah_c_eblcr, sizeof(nehemiah_c_eblcr));
                        break;
                }
                break;

        default:
                cpuname = "Unknown";
                break;
        }

        printk (KERN_INFO PFX "VIA %s CPU detected.  ", cpuname);
        switch (longhaul_version) {
        case TYPE_LONGHAUL_V1:
        case TYPE_LONGHAUL_V2:
                printk ("Longhaul v%d supported.\n", longhaul_version);
                break;
        case TYPE_POWERSAVER:
                printk ("Powersaver supported.\n");
                break;
        };

        /* Find ACPI data for processor */
        acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
                            &longhaul_walk_callback, NULL, (void *)&pr);
        if (pr == NULL)
                goto err_acpi;

        if (longhaul_version == TYPE_POWERSAVER) {
                /* Check ACPI support for C3 state */
                cx = &pr->power.states[ACPI_STATE_C3];
                if (cx->address > 0 &&
                   (cx->latency <= 1000 || ignore_latency != 0) ) {
                        goto print_support_type;
                }
        }
        /* Check ACPI support for bus master arbiter disable */
        if (!pr->flags.bm_control) {
                if (enable_arbiter_disable()) {
                        port22_en = 1;
                } else {
                        goto err_acpi;
                }
        }
print_support_type:
        if (!port22_en) {
                printk (KERN_INFO PFX "Using ACPI support.\n");
        } else {
                printk (KERN_INFO PFX "Using northbridge support.\n");
        }

        ret = longhaul_get_ranges();
        if (ret != 0)
                return ret;

        if ((longhaul_version==TYPE_LONGHAUL_V2 || longhaul_version==TYPE_POWERSAVER) &&
                 (scale_voltage != 0))
                longhaul_setup_voltagescaling();

        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
        policy->cpuinfo.transition_latency = 200000;    /* nsec */
        policy->cur = calc_speed(longhaul_get_cpu_mult());

        ret = cpufreq_frequency_table_cpuinfo(policy, longhaul_table);
        if (ret)
                return ret;

        cpufreq_frequency_table_get_attr(longhaul_table, policy->cpu);

        return 0;

err_acpi:
        printk(KERN_ERR PFX "No ACPI support. Unsupported northbridge. Aborting.\n");
        return -ENODEV;
}

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

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

static struct cpufreq_driver longhaul_driver = {
        .verify = longhaul_verify,
        .target = longhaul_target,
        .get    = longhaul_get,
        .init   = longhaul_cpu_init,
        .exit   = __devexit_p(longhaul_cpu_exit),
        .name   = "longhaul",
        .owner  = THIS_MODULE,
        .attr   = longhaul_attr,
};


static int __init longhaul_init(void)
{
        struct cpuinfo_x86 *c = cpu_data;

        if (c->x86_vendor != X86_VENDOR_CENTAUR || c->x86 != 6)
                return -ENODEV;

#ifdef CONFIG_SMP
        if (num_online_cpus() > 1) {
                return -ENODEV;
                printk(KERN_ERR PFX "More than 1 CPU detected, longhaul disabled.\n");
        }
#endif
#ifdef CONFIG_X86_IO_APIC
        if (cpu_has_apic) {
                printk(KERN_ERR PFX "APIC detected. Longhaul is currently broken in this configuration.\n");
                return -ENODEV;
        }
#endif
        switch (c->x86_model) {
        case 6 ... 9:
                return cpufreq_register_driver(&longhaul_driver);
        case 10:
                printk(KERN_ERR PFX "Use acpi-cpufreq driver for VIA C7\n");
        default:
        }

        return -ENODEV;
}


static void __exit longhaul_exit(void)
{
        int i;

        for (i=0; i < numscales; i++) {
                if (clock_ratio[i] == maxmult) {
                        longhaul_setstate(i);
                        break;
                }
        }

        cpufreq_unregister_driver(&longhaul_driver);
        kfree(longhaul_table);
}

module_param (scale_voltage, int, 0644);
MODULE_PARM_DESC(scale_voltage, "Scale voltage of processor");
module_param(ignore_latency, int, 0644);
MODULE_PARM_DESC(ignore_latency, "Skip ACPI C3 latency test");

MODULE_AUTHOR ("Dave Jones <davej@codemonkey.org.uk>");
MODULE_DESCRIPTION ("Longhaul driver for VIA Cyrix processors.");
MODULE_LICENSE ("GPL");

late_initcall(longhaul_init);
module_exit(longhaul_exit);