Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1002 insertions, 0 deletions

diff --git a/drivers/cpufreq/longhaul.c b/drivers/cpufreq/longhaul.c
new file mode 100644
index 000000000..182a4dbca
--- /dev/null
+++ b/drivers/cpufreq/longhaul.c
@@ -0,0 +1,1002 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  (C) 2001-2004  Dave Jones.
+ *  (C) 2002  Padraig Brady. <padraig@antefacto.com>
+ *
+ *  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*
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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 <asm/cpu_device_id.h>
+#include <acpi/processor.h>
+
+#include "longhaul.h"
+
+#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;
+static int enable;
+
+/* 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 int longhaul_setstate(struct cpufreq_policy *policy,
+		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].driver_data;
+	/* Safety precautions */
+	mult = mults[mults_index & 0x1f];
+	if (mult == -1)
+		return -EINVAL;
+
+	speed = calc_speed(mult);
+	if ((speed > highest_speed) || (speed < lowest_speed))
+		return -EINVAL;
+
+	/* 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;
+
+	pr_debug("Setting to FSB:%dMHz Mult:%d.%dx (%s)\n",
+			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)) {
+		pr_info("Failed to set requested frequency!\n");
+		/* 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) {
+			pr_info("Enabling \"Ignore Revision ID\" option\n");
+			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) {
+			pr_info("Disabling ACPI C3 support\n");
+			longhaul_flags &= ~USE_ACPI_C3;
+			if (revid_errata) {
+				pr_info("Disabling \"Ignore Revision ID\" option\n");
+				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) {
+			pr_info("Switching to Longhaul ver. 1\n");
+			longhaul_version = TYPE_LONGHAUL_V1;
+			msleep(200);
+			goto retry_loop;
+		}
+	}
+
+	if (!bm_timeout) {
+		pr_info("Warning: Timeout while waiting for idle PCI bus\n");
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
+/*
+ * 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 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) {
+		pr_info("Invalid (reserved) multiplier!\n");
+		return -EINVAL;
+	}
+	fsb = guess_fsb(mult);
+	if (fsb == 0) {
+		pr_info("Invalid (reserved) FSB!\n");
+		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\n",
+		 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\n", fsb,
+		 print_speed(lowest_speed/1000),
+		 print_speed(highest_speed/1000));
+
+	if (lowest_speed == highest_speed) {
+		pr_info("highestspeed == lowest, aborting\n");
+		return -EINVAL;
+	}
+	if (lowest_speed > highest_speed) {
+		pr_info("nonsense! lowest (%d > %d) !\n",
+			lowest_speed, highest_speed);
+		return -EINVAL;
+	}
+
+	longhaul_table = kcalloc(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].driver_data	= 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].driver_data,
+			     longhaul_table[min_i].driver_data);
+		}
+	}
+
+	longhaul_table[k].frequency = CPUFREQ_TABLE_END;
+
+	/* Find index we are running on */
+	for (j = 0; j < k; j++) {
+		if (mults[longhaul_table[j].driver_data & 0x1f] == mult) {
+			longhaul_index = j;
+			break;
+		}
+	}
+	return 0;
+}
+
+
+static void longhaul_setup_voltagescaling(void)
+{
+	struct cpufreq_frequency_table *freq_pos;
+	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)) {
+		pr_info("Voltage scaling not supported by CPU\n");
+		return;
+	}
+
+	if (!longhaul.bits.VRMRev) {
+		pr_info("VRM 8.5\n");
+		vrm_mV_table = &vrm85_mV[0];
+		mV_vrm_table = &mV_vrm85[0];
+	} else {
+		pr_info("Mobile VRM\n");
+		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) {
+		pr_info("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) {
+		pr_info("Claims to support voltage scaling but min & max are both %d.%03d - Voltage scaling disabled\n",
+			maxvid.mV/1000, maxvid.mV%1000);
+		return;
+	}
+
+	/* How many voltage steps*/
+	numvscales = maxvid.pos - minvid.pos + 1;
+	pr_info("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);
+
+	/* 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;
+	}
+	if (min_vid_speed >= highest_speed)
+		return;
+	/* Calculate kHz for one voltage step */
+	kHz_step = (highest_speed - min_vid_speed) / numvscales;
+
+	cpufreq_for_each_entry_idx(freq_pos, longhaul_table, j) {
+		speed = freq_pos->frequency;
+		if (speed > min_vid_speed)
+			pos = (speed - min_vid_speed) / kHz_step + minvid.pos;
+		else
+			pos = minvid.pos;
+		freq_pos->driver_data |= mV_vrm_table[pos] << 8;
+		vid = vrm_mV_table[mV_vrm_table[pos]];
+		pr_info("f: %d kHz, index: %d, vid: %d mV\n",
+			speed, j, vid.mV);
+	}
+
+	can_scale_voltage = 1;
+	pr_info("Voltage scaling enabled\n");
+}
+
+
+static int longhaul_target(struct cpufreq_policy *policy,
+			    unsigned int table_index)
+{
+	unsigned int i;
+	unsigned int dir = 0;
+	u8 vid, current_vid;
+	int retval = 0;
+
+	if (!can_scale_voltage)
+		retval = longhaul_setstate(policy, 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].driver_data >> 8);
+		current_vid &= 0x1f;
+		if (table_index > longhaul_index)
+			dir = 1;
+		while (i != table_index) {
+			vid = (longhaul_table[i].driver_data >> 8) & 0x1f;
+			if (vid != current_vid) {
+				retval = longhaul_setstate(policy, i);
+				current_vid = vid;
+				msleep(200);
+			}
+			if (dir)
+				i++;
+			else
+				i--;
+		}
+		retval = longhaul_setstate(policy, table_index);
+	}
+
+	longhaul_index = table_index;
+	return retval;
+}
+
+
+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)) {
+				pr_err("Can't enable access to port 0x22\n");
+				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;
+			pr_info("ACPI I/O at 0x%x\n", acpi_regs_addr);
+		}
+
+		pci_dev_put(dev);
+		return 1;
+	}
+	return 0;
+}
+
+static int 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_stepping) {
+		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_stepping < 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_stepping) {
+		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;
+	}
+
+	pr_info("VIA %s CPU detected.  ", cpuname);
+	switch (longhaul_version) {
+	case TYPE_LONGHAUL_V1:
+	case TYPE_LONGHAUL_V2:
+		pr_cont("Longhaul v%d supported\n", longhaul_version);
+		break;
+	case TYPE_POWERSAVER:
+		pr_cont("Powersaver supported\n");
+		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))) {
+		pr_err("No ACPI support: Unsupported northbridge\n");
+		return -ENODEV;
+	}
+
+	if (longhaul_flags & USE_NORTHBRIDGE)
+		pr_info("Using northbridge support\n");
+	if (longhaul_flags & USE_ACPI_C3)
+		pr_info("Using ACPI support\n");
+
+	ret = longhaul_get_ranges();
+	if (ret != 0)
+		return ret;
+
+	if ((longhaul_version != TYPE_LONGHAUL_V1) && (scale_voltage != 0))
+		longhaul_setup_voltagescaling();
+
+	policy->transition_delay_us = 200000;	/* usec */
+	policy->freq_table = longhaul_table;
+
+	return 0;
+}
+
+static struct cpufreq_driver longhaul_driver = {
+	.verify	= cpufreq_generic_frequency_table_verify,
+	.target_index = longhaul_target,
+	.get	= longhaul_get,
+	.init	= longhaul_cpu_init,
+	.name	= "longhaul",
+	.attr	= cpufreq_generic_attr,
+};
+
+static const struct x86_cpu_id longhaul_id[] = {
+	X86_MATCH_VENDOR_FAM(CENTAUR, 6, NULL),
+	{}
+};
+MODULE_DEVICE_TABLE(x86cpu, longhaul_id);
+
+static int __init longhaul_init(void)
+{
+	struct cpuinfo_x86 *c = &cpu_data(0);
+
+	if (!x86_match_cpu(longhaul_id))
+		return -ENODEV;
+
+	if (!enable) {
+		pr_err("Option \"enable\" not set - Aborting\n");
+		return -ENODEV;
+	}
+#ifdef CONFIG_SMP
+	if (num_online_cpus() > 1) {
+		pr_err("More than 1 CPU detected, longhaul disabled\n");
+		return -ENODEV;
+	}
+#endif
+#ifdef CONFIG_X86_IO_APIC
+	if (boot_cpu_has(X86_FEATURE_APIC)) {
+		pr_err("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:
+		pr_err("Use acpi-cpufreq driver for VIA C7\n");
+	default:
+		;
+	}
+
+	return -ENODEV;
+}
+
+
+static void __exit longhaul_exit(void)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(0);
+	int i;
+
+	for (i = 0; i < numscales; i++) {
+		if (mults[i] == maxmult) {
+			struct cpufreq_freqs freqs;
+
+			freqs.old = policy->cur;
+			freqs.new = longhaul_table[i].frequency;
+			freqs.flags = 0;
+
+			cpufreq_freq_transition_begin(policy, &freqs);
+			longhaul_setstate(policy, i);
+			cpufreq_freq_transition_end(policy, &freqs, 0);
+			break;
+		}
+	}
+
+	cpufreq_cpu_put(policy);
+	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");
+/* By default driver is disabled to prevent incompatible
+ * system freeze. */
+module_param(enable, int, 0644);
+MODULE_PARM_DESC(enable, "Enable driver");
+
+MODULE_AUTHOR("Dave Jones");
+MODULE_DESCRIPTION("Longhaul driver for VIA Cyrix processors.");
+MODULE_LICENSE("GPL");
+
+late_initcall(longhaul_init);
+module_exit(longhaul_exit);