longhaul.c

linux-2.6.15.6

/*
 *  (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 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/slab.h>
#include <linux/string.h>
#include <linux/pci.h>

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


#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 int voltage_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) {
		if (speed%1000 == 0)
			sprintf (speedbuffer, "%dGHz", speed/1000);
		else
			sprintf (speedbuffer, "%d.%dGHz", speed/1000, (speed%1000)/100);
	} else
		sprintf (speedbuffer, "%dMHz", speed);

	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];
}


static void do_powersaver(union msr_longhaul *longhaul,
			unsigned int clock_ratio_index)
{
	struct pci_dev *dev;
	unsigned long flags;
	unsigned int tmp_mask;
	int version;
	int i;
	u16 pci_cmd;
	u16 cmd_state[64];

	switch (cpu_model) {
	case CPU_EZRA_T:
		version = 3;
		break;
	case CPU_NEHEMIAH:
		version = 0xf;
		break;
	default:
		return;
	}

	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 = 0;

	preempt_disable();
	local_irq_save(flags);

	/*
	 * get current pci bus master state for all devices
	 * and clear bus master bit
	 */
	dev = NULL;
	i = 0;
	do {
		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
		if (dev != NULL) {
			pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);
			cmd_state[i++] = pci_cmd;
			pci_cmd &= ~PCI_COMMAND_MASTER;
			pci_write_config_word(dev, PCI_COMMAND, pci_cmd);
		}
	} while (dev != NULL);

	tmp_mask=inb(0x21);	/* works on C3. save mask. */
	outb(0xFE,0x21);	/* TMR0 only */
	outb(0xFF,0x80);	/* delay */

	safe_halt();
	wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
	halt();

	local_irq_disable();

	outb(tmp_mask,0x21);	/* restore mask */

	/* restore pci bus master state for all devices */
	dev = NULL;
	i = 0;
	do {
		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
		if (dev != NULL) {
			pci_cmd = cmd_state[i++];
			pci_write_config_byte(dev, PCI_COMMAND, pci_cmd);
		}
	} while (dev != NULL);
	local_irq_restore(flags);
	preempt_enable();

	/* disable bus ratio bit */
	rdmsrl(MSR_VIA_LONGHAUL, longhaul->val);
	longhaul->bits.EnableSoftBusRatio = 0;
	longhaul->bits.RevisionKey = version;
	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;
	union msr_longhaul longhaul;
	union msr_bcr2 bcr2;
	static unsigned int old_ratio=-1;

	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));

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

		/* Disable software clock multiplier */
		rdmsrl (MSR_VIA_BCR2, bcr2.val);
		bcr2.bits.ESOFTBF = 0;
		local_irq_disable();
		wrmsrl (MSR_VIA_BCR2, bcr2.val);
		local_irq_enable();
		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:
		do_powersaver(&longhaul, clock_ratio_index);
		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)
{
	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 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;