path: root/drivers/cpufreq/longhaul.c

/*
 *  (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 &