/*

   *  (C) 2001-2004  Dave Jones. <davej@redhat.com>

   *  (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 backward compatible with v1, but adds
   *   LONGHAUL MSR for purpose of both frequency and voltage scaling.
   *   Present in Samuel 2 (steppings 1-7 only) (C5B), and Ezra (C5C).

   *  Version 3 of longhaul got renamed to Powersaver and redesigned

   *   to use only 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 <linux/delay.h>

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

  
  #include <asm/msr.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

  #define	CPU_NEHEMIAH_C	6

  /* Flags */
  #define USE_ACPI_C3		(1 << 1)
  #define USE_NORTHBRIDGE		(1 << 2)

  static int cpu_model;

  static unsigned int numscales = 16;

  static unsigned int fsb;

  static const struct mV_pos *vrm_mV_table;
  static const unsigned char *mV_vrm_table;

  
  static unsigned int highest_speed, lowest_speed; /* kHz */

  static unsigned int minmult, maxmult;
  static int can_scale_voltage;

  static struct acpi_processor *pr;
  static struct acpi_processor_cx *cx;

  static u32 acpi_regs_addr;

  static u8 longhaul_flags;

  static unsigned int longhaul_index;

  
  /* Module parameters */

  static int scale_voltage;

  static int disable_acpi_c3;

  static int revid_errata;

  /* Clock ratios multiplied by 10 */

  static int mults[32];
  static int eblcr[32];

  static int longhaul_version;
  static struct cpufreq_frequency_table *longhaul_table;

  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;
  }

  
  
  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[invalue];

  }

  /* For processor with BCR2 MSR */

  static void do_longhaul1(unsigned int mults_index)

  {

  	union msr_bcr2 bcr2;

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

  	bcr2.bits.CLOCKMUL = mults_index & 0xff;

  	/* 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 mults_index,

  			  unsigned int dir)

  {
  	union msr_longhaul longhaul;
  	u32 t;

  	rdmsrl(MSR_VIA_LONGHAUL, longhaul.val);

  	/* Setup new frequency */

  	if (!revid_errata)
  		longhaul.bits.RevisionKey = longhaul.bits.RevisionID;
  	else
  		longhaul.bits.RevisionKey = 0;

  	longhaul.bits.SoftBusRatio = mults_index & 0xf;
  	longhaul.bits.SoftBusRatio4 = (mults_index & 0x10) >> 4;

  	/* Setup new voltage */
  	if (can_scale_voltage)

  		longhaul.bits.SoftVID = (mults_index >> 8) & 0x1f;

  	/* Sync to timer tick */
  	safe_halt();
  	/* Raise voltage if necessary */

  	if (can_scale_voltage && dir) {

  		longhaul.bits.EnableSoftVID = 1;

  		wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
  		/* Change voltage */
  		if (!cx_address) {
  			ACPI_FLUSH_CPU_CACHE();
  			halt();
  		} else {
  			ACPI_FLUSH_CPU_CACHE();
  			/* Invoke C3 */
  			inb(cx_address);
  			/* Dummy op - must do something useless after P_LVL3
  			 * read */

  			t = inl(acpi_gbl_FADT.xpm_timer_block.address);

  		}
  		longhaul.bits.EnableSoftVID = 0;
  		wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);

  	}

  	/* Change frequency on next halt or sleep */

  	longhaul.bits.EnableSoftBusRatio = 1;

  	wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);

  	if (!cx_address) {

  		ACPI_FLUSH_CPU_CACHE();

  		halt();
  	} else {
  		ACPI_FLUSH_CPU_CACHE();
  		/* Invoke C3 */
  		inb(cx_address);
  		/* Dummy op - must do something useless after P_LVL3 read */

  		t = inl(acpi_gbl_FADT.xpm_timer_block.address);

  	}

  	/* Disable bus ratio bit */

  	longhaul.bits.EnableSoftBusRatio = 0;

  	wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);

  
  	/* Reduce voltage if necessary */

  	if (can_scale_voltage && !dir) {

  		longhaul.bits.EnableSoftVID = 1;
  		wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
  		/* Change voltage */
  		if (!cx_address) {
  			ACPI_FLUSH_CPU_CACHE();
  			halt();
  		} else {
  			ACPI_FLUSH_CPU_CACHE();
  			/* Invoke C3 */
  			inb(cx_address);
  			/* Dummy op - must do something useless after P_LVL3
  			 * read */

  			t = inl(acpi_gbl_FADT.xpm_timer_block.address);

  		}
  		longhaul.bits.EnableSoftVID = 0;
  		wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);

  	}

  }
  
  /**
   * longhaul_set_cpu_frequency()

   * @mults_index : bitpattern of the new multiplier.

   *
   * Sets a new clock ratio.
   */

  static void longhaul_setstate(unsigned int table_index)

  {

  	unsigned int mults_index;

  	int speed, mult;
  	struct cpufreq_freqs freqs;

  	unsigned long flags;
  	unsigned int pic1_mask, pic2_mask;

  	u16 bm_status = 0;

  	u32 bm_timeout = 1000;

  	unsigned int dir = 0;

  	mults_index = longhaul_table[table_index].index;

  	/* Safety precautions */

  	mult = mults[mults_index & 0x1f];

  	if (mult == -1)
  		return;

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

  	/* Voltage transition before frequency transition? */
  	if (can_scale_voltage && longhaul_index < table_index)
  		dir = 1;

  
  	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);

  	pr_debug("Setting to FSB:%dMHz Mult:%d.%dx (%s)
  ",

  			fsb, mult/10, mult%10, print_speed(speed/1000));

  retry_loop:

  	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 */

  	/* Wait while PCI bus is busy. */

  	if (acpi_regs_addr && (longhaul_flags & USE_NORTHBRIDGE
  	    || ((pr != NULL) && pr->flags.bm_control))) {
  		bm_status = inw(acpi_regs_addr);

  		bm_status &= 1 << 4;

  		while (bm_status && bm_timeout) {

  			outw(1 << 4, acpi_regs_addr);

  			bm_timeout--;

  			bm_status = inw(acpi_regs_addr);

  			bm_status &= 1 << 4;

  		}
  	}

  	if (longhaul_flags & USE_NORTHBRIDGE) {
  		/* Disable AGP and PCI arbiters */
  		outb(3, 0x22);
  	} else if ((pr != NULL) && pr->flags.bm_control) {

  		/* Disable bus master arbitration */

  		acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);

  	}

  	switch (longhaul_version) {
  
  	/*
  	 * Longhaul v1. (Samuel[C5A] and Samuel2 stepping 0[C5B])
  	 * Software controlled multipliers only.

  	 */
  	case TYPE_LONGHAUL_V1:

  		do_longhaul1(mults_index);

  		break;
  
  	/*

  	 * Longhaul v2 appears in Samuel2 Steppings 1->7 [C5B] and Ezra [C5C]
  	 *

  	 * Longhaul v3 (aka Powersaver). (Ezra-T [C5M] & Nehemiah [C5N])

  	 * Nehemiah can do FSB scaling too, but this has never been proven
  	 * to work in practice.
  	 */

  	case TYPE_LONGHAUL_V2:

  	case TYPE_POWERSAVER:

  		if (longhaul_flags & USE_ACPI_C3) {
  			/* Don't allow wakeup */

  			acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, 0);

  			do_powersaver(cx->address, mults_index, dir);

  		} else {

  			do_powersaver(0, mults_index, dir);

  		}

  		break;
  	}

  	if (longhaul_flags & USE_NORTHBRIDGE) {
  		/* Enable arbiters */
  		outb(0, 0x22);
  	} else if ((pr != NULL) && pr->flags.bm_control) {

  		/* Enable bus master arbitration */

  		acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);

  	}

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

  
  	local_irq_restore(flags);
  	preempt_enable();

  	freqs.new = calc_speed(longhaul_get_cpu_mult());

  	/* Check if requested frequency is set. */
  	if (unlikely(freqs.new != speed)) {
  		printk(KERN_INFO PFX "Failed to set requested frequency!
  ");
  		/* Revision ID = 1 but processor is expecting revision key
  		 * equal to 0. Jumpers at the bottom of processor will change
  		 * multiplier and FSB, but will not change bits in Longhaul
  		 * MSR nor enable voltage scaling. */
  		if (!revid_errata) {
  			printk(KERN_INFO PFX "Enabling \"Ignore Revision ID\" "
  						"option.
  ");
  			revid_errata = 1;
  			msleep(200);
  			goto retry_loop;
  		}
  		/* Why ACPI C3 sometimes doesn't work is a mystery for me.
  		 * But it does happen. Processor is entering ACPI C3 state,
  		 * but it doesn't change frequency. I tried poking various
  		 * bits in northbridge registers, but without success. */
  		if (longhaul_flags & USE_ACPI_C3) {
  			printk(KERN_INFO PFX "Disabling ACPI C3 support.
  ");
  			longhaul_flags &= ~USE_ACPI_C3;
  			if (revid_errata) {
  				printk(KERN_INFO PFX "Disabling \"Ignore "
  						"Revision ID\" option.
  ");
  				revid_errata = 0;
  			}
  			msleep(200);
  			goto retry_loop;
  		}
  		/* This shouldn't happen. Longhaul ver. 2 was reported not
  		 * working on processors without voltage scaling, but with
  		 * RevID = 1. RevID errata will make things right. Just
  		 * to be 100% sure. */
  		if (longhaul_version == TYPE_LONGHAUL_V2) {
  			printk(KERN_INFO PFX "Switching to Longhaul ver. 1
  ");
  			longhaul_version = TYPE_LONGHAUL_V1;
  			msleep(200);
  			goto retry_loop;
  		}
  	}
  	/* Report true CPU frequency */

  	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

  
  	if (!bm_timeout)

  		printk(KERN_INFO PFX "Warning: Timeout while waiting for "
  				"idle PCI bus.
  ");

  }
  
  /*
   * 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_fsb(int mult)

  {

  	int speed = cpu_khz / 1000;

  	int i;

  	int speeds[] = { 666, 1000, 1333, 2000 };
  	int f_max, f_min;
  
  	for (i = 0; i < 4; i++) {
  		f_max = ((speeds[i] * mult) + 50) / 100;
  		f_max += (ROUNDING / 2);
  		f_min = f_max - ROUNDING;
  		if ((speed <= f_max) && (speed >= f_min))
  			return speeds[i] / 10;

  	}
  	return 0;
  }

  static int __cpuinit longhaul_get_ranges(void)

  {

  	unsigned int i, j, k = 0;
  	unsigned int ratio;

  	int mult;

  	/* Get current frequency */
  	mult = longhaul_get_cpu_mult();
  	if (mult == -1) {
  		printk(KERN_INFO PFX "Invalid (reserved) multiplier!
  ");
  		return -EINVAL;
  	}
  	fsb = guess_fsb(mult);
  	if (fsb == 0) {
  		printk(KERN_INFO PFX "Invalid (reserved) FSB!
  ");
  		return -EINVAL;
  	}
  	/* Get max multiplier - as we always did.

  	 * Longhaul MSR is useful only when voltage scaling is enabled.

  	 * C3 is booting at max anyway. */
  	maxmult = mult;
  	/* Get min multiplier */

  	switch (cpu_model) {
  	case CPU_NEHEMIAH:
  		minmult = 50;

  		break;

  	case CPU_NEHEMIAH_C:
  		minmult = 40;
  		break;
  	default:
  		minmult = 30;

  		break;

  	}

  	pr_debug("MinMult:%d.%dx MaxMult:%d.%dx
  ",

  		 minmult/10, minmult%10, maxmult/10, maxmult%10);

  	highest_speed = calc_speed(maxmult);
  	lowest_speed = calc_speed(minmult);

  	pr_debug("FSB:%dMHz  Lowest speed: %s   Highest speed:%s
  ", fsb,

  		 print_speed(lowest_speed/1000),

  		 print_speed(highest_speed/1000));
  
  	if (lowest_speed == highest_speed) {

  		printk(KERN_INFO PFX "highestspeed == lowest, aborting.
  ");

  		return -EINVAL;
  	}
  	if (lowest_speed > highest_speed) {

  		printk(KERN_INFO PFX "nonsense! lowest (%d > %d) !
  ",

  			lowest_speed, highest_speed);
  		return -EINVAL;
  	}

  	longhaul_table = kmalloc((numscales + 1) * sizeof(*longhaul_table),
  			GFP_KERNEL);
  	if (!longhaul_table)

  		return -ENOMEM;

  	for (j = 0; j < numscales; j++) {

  		ratio = mults[j];

  		if (ratio == -1)
  			continue;
  		if (ratio > maxmult || ratio < minmult)
  			continue;
  		longhaul_table[k].frequency = calc_speed(ratio);
  		longhaul_table[k].index	= j;
  		k++;
  	}

  	if (k <= 1) {
  		kfree(longhaul_table);
  		return -ENODEV;
  	}
  	/* Sort */
  	for (j = 0; j < k - 1; j++) {
  		unsigned int min_f, min_i;
  		min_f = longhaul_table[j].frequency;
  		min_i = j;
  		for (i = j + 1; i < k; i++) {
  			if (longhaul_table[i].frequency < min_f) {
  				min_f = longhaul_table[i].frequency;
  				min_i = i;
  			}
  		}
  		if (min_i != j) {

  			swap(longhaul_table[j].frequency,
  			     longhaul_table[min_i].frequency);
  			swap(longhaul_table[j].index,
  			     longhaul_table[min_i].index);

  		}
  	}

  
  	longhaul_table[k].frequency = CPUFREQ_TABLE_END;

  	/* Find index we are running on */
  	for (j = 0; j < k; j++) {

  		if (mults[longhaul_table[j].index & 0x1f] == mult) {

  			longhaul_index = j;
  			break;
  		}
  	}

  	return 0;
  }

  static void __cpuinit longhaul_setup_voltagescaling(void)

  {
  	union msr_longhaul longhaul;

  	struct mV_pos minvid, maxvid, vid;

  	unsigned int j, speed, pos, kHz_step, numvscales;

  	int min_vid_speed;

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

  		return;

  	}
  
  	if (!longhaul.bits.VRMRev) {

  		printk(KERN_INFO PFX "VRM 8.5
  ");

  		vrm_mV_table = &vrm85_mV[0];
  		mV_vrm_table = &mV_vrm85[0];
  	} else {

  		printk(KERN_INFO PFX "Mobile VRM
  ");

  		if (cpu_model < CPU_NEHEMIAH)
  			return;

  		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];

  	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.
  ",

  					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
  ",

  				maxvid.mV/1000, maxvid.mV%1000);

  		return;
  	}

  	/* How many voltage steps*/

  	numvscales = maxvid.pos - minvid.pos + 1;
  	printk(KERN_INFO PFX
  		"Max VID=%d.%03d  "
  		"Min VID=%d.%03d, "
  		"%d possible voltage scales
  ",

  		maxvid.mV/1000, maxvid.mV%1000,
  		minvid.mV/1000, minvid.mV%1000,
  		numvscales);

  
  	/* Calculate max frequency at min voltage */
  	j = longhaul.bits.MinMHzBR;
  	if (longhaul.bits.MinMHzBR4)
  		j += 16;

  	min_vid_speed = eblcr[j];

  	if (min_vid_speed == -1)
  		return;
  	switch (longhaul.bits.MinMHzFSB) {
  	case 0:
  		min_vid_speed *= 13333;
  		break;
  	case 1:
  		min_vid_speed *= 10000;
  		break;
  	case 3:
  		min_vid_speed *= 6666;
  		break;
  	default:
  		return;
  		break;
  	}
  	if (min_vid_speed >= highest_speed)
  		return;
  	/* Calculate kHz for one voltage step */
  	kHz_step = (highest_speed - min_vid_speed) / numvscales;

  	j = 0;
  	while (longhaul_table[j].frequency != CPUFREQ_TABLE_END) {
  		speed = longhaul_table[j].frequency;

  		if (speed > min_vid_speed)
  			pos = (speed - min_vid_speed) / kHz_step + minvid.pos;
  		else
  			pos = minvid.pos;

  		longhaul_table[j].index |= mV_vrm_table[pos] << 8;
  		vid = vrm_mV_table[mV_vrm_table[pos]];

  		printk(KERN_INFO PFX "f: %d kHz, index: %d, vid: %d mV
  ",
  				speed, j, vid.mV);

  		j++;

  	}

  	can_scale_voltage = 1;

  	printk(KERN_INFO PFX "Voltage scaling enabled.
  ");

  }
  
  
  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 i;
  	unsigned int dir = 0;
  	u8 vid, current_vid;

  	if (cpufreq_frequency_table_target(policy, longhaul_table, target_freq,
  				relation, &table_index))

  		return -EINVAL;

  	/* Don't set same frequency again */
  	if (longhaul_index == table_index)
  		return 0;

  	if (!can_scale_voltage)
  		longhaul_setstate(table_index);
  	else {
  		/* On test system voltage transitions exceeding single
  		 * step up or down were turning motherboard off. Both
  		 * "ondemand" and "userspace" are unsafe. C7 is doing
  		 * this in hardware, C3 is old and we need to do this
  		 * in software. */
  		i = longhaul_index;

  		current_vid = (longhaul_table[longhaul_index].index >> 8);
  		current_vid &= 0x1f;

  		if (table_index > longhaul_index)
  			dir = 1;
  		while (i != table_index) {
  			vid = (longhaul_table[i].index >> 8) & 0x1f;
  			if (vid != current_vid) {
  				longhaul_setstate(i);
  				current_vid = vid;
  				msleep(200);
  			}
  			if (dir)
  				i++;
  			else
  				i--;
  		}
  		longhaul_setstate(table_index);
  	}
  	longhaul_index = table_index;

  	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 = 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 status = 1;

  	int reg;

  	u8 pci_cmd;
  
  	/* Find PLE133 host bridge */

  	reg = 0x78;

  	dev = pci_get_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8601_0,
  			     NULL);

  	/* Find PM133/VT8605 host bridge */
  	if (dev == NULL)
  		dev = pci_get_device(PCI_VENDOR_ID_VIA,
  				     PCI_DEVICE_ID_VIA_8605_0, NULL);

  	/* Find CLE266 host bridge */
  	if (dev == NULL) {

  		reg = 0x76;

  		dev = pci_get_device(PCI_VENDOR_ID_VIA,
  				     PCI_DEVICE_ID_VIA_862X_0, NULL);

  		/* Find CN400 V-Link host bridge */
  		if (dev == NULL)

  			dev = pci_get_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);

  			pci_read_config_byte(dev, reg, &pci_cmd);
  			if (!(pci_cmd & 1<<7)) {
  				printk(KERN_ERR PFX
  					"Can't enable access to port 0x22.
  ");

  				status = 0;

  			}

  		}

  		pci_dev_put(dev);
  		return status;

  	}
  	return 0;
  }

  static int longhaul_setup_southbridge(void)

  {
  	struct pci_dev *dev;
  	u8 pci_cmd;
  
  	/* Find VT8235 southbridge */

  	dev = pci_get_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235, NULL);

  	if (dev == NULL)

  		/* Find VT8237 southbridge */

  		dev = pci_get_device(PCI_VENDOR_ID_VIA,
  				     PCI_DEVICE_ID_VIA_8237, NULL);

  	if (dev != NULL) {
  		/* Set transition time to max */
  		pci_read_config_byte(dev, 0xec, &pci_cmd);
  		pci_cmd &= ~(1 << 2);
  		pci_write_config_byte(dev, 0xec, pci_cmd);
  		pci_read_config_byte(dev, 0xe4, &pci_cmd);
  		pci_cmd &= ~(1 << 7);
  		pci_write_config_byte(dev, 0xe4, pci_cmd);
  		pci_read_config_byte(dev, 0xe5, &pci_cmd);
  		pci_cmd |= 1 << 7;
  		pci_write_config_byte(dev, 0xe5, pci_cmd);

  		/* Get address of ACPI registers block*/
  		pci_read_config_byte(dev, 0x81, &pci_cmd);
  		if (pci_cmd & 1 << 7) {
  			pci_read_config_dword(dev, 0x88, &acpi_regs_addr);
  			acpi_regs_addr &= 0xff00;

  			printk(KERN_INFO PFX "ACPI I/O at 0x%x
  ",
  					acpi_regs_addr);

  		}

  		pci_dev_put(dev);

  		return 1;
  	}
  	return 0;
  }

  static int __cpuinit longhaul_cpu_init(struct cpufreq_policy *policy)

  {

  	struct cpuinfo_x86 *c = &cpu_data(0);

  	char *cpuname = NULL;

  	int ret;

  	u32 lo, hi;

  	/* 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(mults, samuel1_mults, sizeof(samuel1_mults));
  		memcpy(eblcr, samuel1_eblcr, sizeof(samuel1_eblcr));

  		break;
  
  	case 7:

  		switch (c->x86_mask) {
  		case 0:

  			longhaul_version = TYPE_LONGHAUL_V1;

  			cpu_model = CPU_SAMUEL2;
  			cpuname = "C3 'Samuel 2' [C5B]";

  			/* Note, this is not a typo, early Samuel2's had
  			 * Samuel1 ratios. */

  			memcpy(mults, samuel1_mults, sizeof(samuel1_mults));
  			memcpy(eblcr, samuel2_eblcr, sizeof(samuel2_eblcr));

  			break;
  		case 1 ... 15:

  			longhaul_version = TYPE_LONGHAUL_V2;

  			if (c->x86_mask < 8) {
  				cpu_model = CPU_SAMUEL2;
  				cpuname = "C3 'Samuel 2' [C5B]";
  			} else {
  				cpu_model = CPU_EZRA;
  				cpuname = "C3 'Ezra' [C5C]";
  			}

  			memcpy(mults, ezra_mults, sizeof(ezra_mults));
  			memcpy(eblcr, 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(mults, ezrat_mults, sizeof(ezrat_mults));
  		memcpy(eblcr, ezrat_eblcr, sizeof(ezrat_eblcr));

  		break;
  
  	case 9:

  		longhaul_version = TYPE_POWERSAVER;

  		numscales = 32;

  		memcpy(mults, nehemiah_mults, sizeof(nehemiah_mults));
  		memcpy(eblcr, nehemiah_eblcr, sizeof(nehemiah_eblcr));

  		switch (c->x86_mask) {
  		case 0 ... 1:

  			cpu_model = CPU_NEHEMIAH;

  			cpuname = "C3 'Nehemiah A' [C5XLOE]";

  			break;
  		case 2 ... 4:

  			cpu_model = CPU_NEHEMIAH;

  			cpuname = "C3 'Nehemiah B' [C5XLOH]";

  			break;
  		case 5 ... 15:

  			cpu_model = CPU_NEHEMIAH_C;

  			cpuname = "C3 'Nehemiah C' [C5P]";

  			break;
  		}
  		break;
  
  	default:
  		cpuname = "Unknown";
  		break;
  	}

  	/* Check Longhaul ver. 2 */
  	if (longhaul_version == TYPE_LONGHAUL_V2) {
  		rdmsr(MSR_VIA_LONGHAUL, lo, hi);
  		if (lo == 0 && hi == 0)
  			/* Looks like MSR isn't present */
  			longhaul_version = TYPE_LONGHAUL_V1;
  	}

  	printk(KERN_INFO PFX "VIA %s CPU detected.  ", cpuname);

  	switch (longhaul_version) {
  	case TYPE_LONGHAUL_V1:
  	case TYPE_LONGHAUL_V2:

  		printk(KERN_CONT "Longhaul v%d supported.
  ", longhaul_version);

  		break;
  	case TYPE_POWERSAVER:

  		printk(KERN_CONT "Powersaver supported.
  ");

  		break;
  	};

  	/* Doesn't hurt */

  	longhaul_setup_southbridge();

  	/* Find ACPI data for processor */

  	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,

  				ACPI_UINT32_MAX, &longhaul_walk_callback, NULL,

  				NULL, (void *)&pr);

  	/* Check ACPI support for C3 state */

  	if (pr != NULL && longhaul_version == TYPE_POWERSAVER) {

  		cx = &pr->power.states[ACPI_STATE_C3];

  		if (cx->address > 0 && cx->latency <= 1000)

  			longhaul_flags |= USE_ACPI_C3;

  	}

  	/* Disable if it isn't working */
  	if (disable_acpi_c3)
  		longhaul_flags &= ~USE_ACPI_C3;

  	/* Check if northbridge is friendly */

  	if (enable_arbiter_disable())

  		longhaul_flags |= USE_NORTHBRIDGE;

  	/* Check ACPI support for bus master arbiter disable */

  	if (!(longhaul_flags & USE_ACPI_C3
  	     || longhaul_flags & USE_NORTHBRIDGE)
  	    && ((pr == NULL) || !(pr->flags.bm_control))) {

  		printk(KERN_ERR PFX
  			"No ACPI support. Unsupported northbridge.
  ");
  		return -ENODEV;

  	}

  	if (longhaul_flags & USE_NORTHBRIDGE)

  		printk(KERN_INFO PFX "Using northbridge support.
  ");
  	if (longhaul_flags & USE_ACPI_C3)
  		printk(KERN_INFO PFX "Using ACPI support.
  ");

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

  	if ((longhaul_version != TYPE_LONGHAUL_V1) && (scale_voltage != 0))

  		longhaul_setup_voltagescaling();

  	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;
  }
  
  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(0);

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

  #ifdef CONFIG_SMP
  	if (num_online_cpus() > 1) {

  		printk(KERN_ERR PFX "More than 1 CPU detected, "
  				"longhaul disabled.
  ");

  		return -ENODEV;

  	}
  #endif
  #ifdef CONFIG_X86_IO_APIC
  	if (cpu_has_apic) {

  		printk(KERN_ERR PFX "APIC detected. Longhaul is currently "
  				"broken in this configuration.
  ");

  		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
  ");

  	default:

  		;

  	}
  
  	return -ENODEV;
  }
  
  
  static void __exit longhaul_exit(void)
  {

  	int i;

  	for (i = 0; i < numscales; i++) {
  		if (mults[i] == maxmult) {

  			longhaul_setstate(i);
  			break;
  		}
  	}
  
  	cpufreq_unregister_driver(&longhaul_driver);
  	kfree(longhaul_table);
  }

  /* Even if BIOS is exporting ACPI C3 state, and it is used
   * with success when CPU is idle, this state doesn't
   * trigger frequency transition in some cases. */

  module_param(disable_acpi_c3, int, 0644);

  MODULE_PARM_DESC(disable_acpi_c3, "Don't use ACPI C3 support");

  /* Change CPU voltage with frequency. Very useful to save

   * power, but most VIA C3 processors aren't supporting it. */

  module_param(scale_voltage, int, 0644);

  MODULE_PARM_DESC(scale_voltage, "Scale voltage of processor");

  /* Force revision key to 0 for processors which doesn't
   * support voltage scaling, but are introducing itself as
   * such. */
  module_param(revid_errata, int, 0644);
  MODULE_PARM_DESC(revid_errata, "Ignore CPU Revision ID");

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

  late_initcall(longhaul_init);

  module_exit(longhaul_exit);