longhaul.c

来自「优龙2410linux2.6.8内核源代码」· C语言 代码 · 共 588 行 · 第 1/2 页

/*
 *  (C) 2001-2004  Dave Jones. <[e-mail]>
 *  (C) 2002  Padraig Brady. <[e-mail]>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *  Based upon datasheets & sample CPUs kindly provided by VIA.
 *
 *  VIA have currently 2 different versions of Longhaul.
 *  Version 1 (Longhaul) uses the BCR2 MSR at 0x1147.
 *   It is present only in Samuel 1, Samuel 2 and Ezra.
 *  Version 2 (Powersaver) uses the POWERSAVER MSR at 0x110a.
 *   It is present in Ezra-T, Nehemiah and above.
 *   In addition to scaling multiplier, it can also scale voltage.
 *   There is provision for scaling FSB too, but this doesn't work
 *   too well in practice.
 *
 *  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/slab.h>
#include <linux/string.h>

#include <asm/msr.h>
#include <asm/timex.h>
#include <asm/io.h>

#include "longhaul.h"

#define PFX "longhaul: "

static unsigned int numscales=16, numvscales;
static unsigned int fsb;
static int minvid, maxvid;
static unsigned int minmult, maxmult;
static int can_scale_voltage;
static int vrmrev;

/* Module parameters */
static int dont_scale_voltage;
static int debug;

static void dprintk(const char *fmt, ...)
{
	char s[256];
	va_list args;

	if (debug == 0)
		return;

	va_start(args, fmt);
	vsprintf(s, fmt, args);
	printk(s);
	va_end(args);
}


#define __hlt()     __asm__ __volatile__("hlt": : :"memory")

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


static unsigned int calc_speed(int mult, int fsb)
{
	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==2 || longhaul_version==3) {
		if (lo & (1<<27))
			invalue+=16;
	}
	return eblcr_table[invalue];
}


/**
 * longhaul_set_cpu_frequency()
 * @clock_ratio_index : bitpattern of the new multiplier.
 *
 * Sets a new clock ratio, and -if applicable- a new Front Side Bus
 */

static void longhaul_setstate(unsigned int clock_ratio_index)
{
	int speed, mult;
	struct cpufreq_freqs freqs;
	union msr_longhaul longhaul;
	union msr_bcr2 bcr2;

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

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

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

	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

	dprintk (KERN_INFO PFX "FSB:%d Mult:%d.%dx\n", fsb, mult/10, mult%10);

	switch (longhaul_version) {
	case 1:
		rdmsrl (MSR_VIA_BCR2, bcr2.val);
		/* Enable software clock multiplier */
		bcr2.bits.ESOFTBF = 1;
		bcr2.bits.CLOCKMUL = clock_ratio_index;
		wrmsrl (MSR_VIA_BCR2, bcr2.val);

		__hlt();

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

	/*
	 * 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.
	 * We also need to do the voltage/freq setting in order depending
	 * on the direction of scaling (like we do in powernow-k7.c)
	 * Ezra-T was alleged to do FSB scaling too, but it never worked in practice.
	 */
	case 2:
		rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
		longhaul.bits.SoftBusRatio = clock_ratio_index & 0xf;
		longhaul.bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
		longhaul.bits.EnableSoftBusRatio = 1;
		/* We must program the revision key only with values we
		 * know about, not blindly copy it from 0:3 */
		longhaul.bits.RevisionKey = 3;	/* SoftVID & SoftBSEL */
		wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
		__hlt();

		rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
		longhaul.bits.EnableSoftBusRatio = 0;
		longhaul.bits.RevisionKey = 3;
		wrmsrl (MSR_VIA_LONGHAUL, longhaul.val);
		break;
	case 3:
		rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
		longhaul.bits.SoftBusRatio = clock_ratio_index & 0xf;
		longhaul.bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
		longhaul.bits.EnableSoftBusRatio = 1;

		longhaul.bits.RevisionKey = 0x0;

		wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
		__hlt();

		rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
		longhaul.bits.EnableSoftBusRatio = 0;
		longhaul.bits.RevisionKey = 0xf;
		wrmsrl (MSR_VIA_LONGHAUL, longhaul.val);
		break;
	}

	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)
{
	struct cpuinfo_x86 *c = cpu_data;
	unsigned long invalue;
	unsigned int multipliers[32]= {
		50,30,40,100,55,35,45,95,90,70,80,60,120,75,85,65,
		-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 1:
		/* 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 (c->x86_model==6)
			fsb = eblcr_fsb_table_v1[invalue];
		else
			fsb = guess_fsb();
		break;

	case 2:
		rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);

		invalue = longhaul.bits.MaxMHzBR;
		if (longhaul.bits.MaxMHzBR4)
			invalue += 16;
		maxmult=multipliers[invalue];

		invalue = longhaul.bits.MinMHzBR;
		if (longhaul.bits.MinMHzBR4 == 1)
			minmult = 30;
		else
			minmult = multipliers[invalue];

		fsb = eblcr_fsb_table_v2[longhaul.bits.MaxMHzFSB];
		break;

	case 3:
		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 5.0x
		 *   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=50;
		maxmult=longhaul_get_cpu_mult();

		fsb = eblcr_fsb_table_v2[longhaul.bits.MaxMHzFSB];
		break;
	}