/*
    hwmon-vid.c - VID/VRM/VRD voltage conversions

    Copyright (c) 2004 Rudolf Marek <r.marek@assembler.cz>

    Partly imported from i2c-vid.h of the lm_sensors project
    Copyright (c) 2002 Mark D. Studebaker <mdsxyz123@yahoo.com>
    With assistance from Trent Piepho <xyzzy@speakeasy.org>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/hwmon-vid.h>

/*
    Common code for decoding VID pins.

    References:

    For VRM 8.4 to 9.1, "VRM x.y DC-DC Converter Design Guidelines",
    available at http://developer.intel.com/.

    For VRD 10.0 and up, "VRD x.y Design Guide",
    available at http://developer.intel.com/.

    AMD Opteron processors don't follow the Intel specifications.
    I'm going to "make up" 2.4 as the spec number for the Opterons.
    No good reason just a mnemonic for the 24x Opteron processor
    series.

    Opteron VID encoding is:
       00000  =  1.550 V
       00001  =  1.525 V
        . . . .
       11110  =  0.800 V
       11111  =  0.000 V (off)

    The 17 specification is in fact Intel Mobile Voltage Positioning -
    (IMVP-II). You can find more information in the datasheet of Max1718
    http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2452

    The 13 specification corresponds to the Intel Pentium M series. There
    doesn't seem to be any named specification for these. The conversion
    tables are detailed directly in the various Pentium M datasheets:
    http://www.intel.com/design/intarch/pentiumm/docs_pentiumm.htm

    The 14 specification corresponds to Intel Core series. There
    doesn't seem to be any named specification for these. The conversion
    tables are detailed directly in the various Pentium Core datasheets:
    http://www.intel.com/design/mobile/datashts/309221.htm

    The 110 (VRM 11) specification corresponds to Intel Conroe based series.
    http://www.intel.com/design/processor/applnots/313214.htm
*/

/* vrm is the VRM/VRD document version multiplied by 10.
   val is the 4-bit or more VID code.
   Returned value is in mV to avoid floating point in the kernel.
   Some VID have some bits in uV scale, this is rounded to mV */
int vid_from_reg(int val, u8 vrm)
{
	int vid;

	switch(vrm) {

	case 100:               /* VRD 10.0 */
		/* compute in uV, round to mV */
		val &= 0x3f;
		if((val & 0x1f) == 0x1f)
			return 0;
		if((val & 0x1f) <= 0x09 || val == 0x0a)
			vid = 1087500 - (val & 0x1f) * 25000;
		else
			vid = 1862500 - (val & 0x1f) * 25000;
		if(val & 0x20)
			vid -= 12500;
		return((vid + 500) / 1000);

	case 110:		/* Intel Conroe */
				/* compute in uV, round to mV */
		val &= 0xff;
		if (val < 0x02 || val > 0xb2)
			return 0;
		return((1600000 - (val - 2) * 6250 + 500) / 1000);
	case 24:                /* Opteron processor */
		val &= 0x1f;
		return(val == 0x1f ? 0 : 1550 - val * 25);

	case 91:		/* VRM 9.1 */
	case 90:		/* VRM 9.0 */
		val &= 0x1f;
		return(val == 0x1f ? 0 :
		                       1850 - val * 25);

	case 85:		/* VRM 8.5 */
		val &= 0x1f;
		return((val & 0x10  ? 25 : 0) +
		       ((val & 0x0f) > 0x04 ? 2050 : 1250) -
		       ((val & 0x0f) * 50));

	case 84:		/* VRM 8.4 */
		val &= 0x0f;
				/* fall through */
	case 82:		/* VRM 8.2 */
		val &= 0x1f;
		return(val == 0x1f ? 0 :
		       val & 0x10  ? 5100 - (val) * 100 :
		                     2050 - (val) * 50);
	case 17:		/* Intel IMVP-II */
		val &= 0x1f;
		return(val & 0x10 ? 975 - (val & 0xF) * 25 :
				    1750 - val * 50);
	case 13:
		val &= 0x3f;
		return(1708 - val * 16);
	case 14:		/* Intel Core */
				/* compute in uV, round to mV */
		val &= 0x7f;
		return(val > 0x77 ? 0 : (1500000 - (val * 12500) + 500) / 1000);
	default:		/* report 0 for unknown */
		printk(KERN_INFO "hwmon-vid: requested unknown VRM version\n");
		return 0;
	}
}


/*
    After this point is the code to automatically determine which
    VRM/VRD specification should be used depending on the CPU.
*/

struct vrm_model {
	u8 vendor;
	u8 eff_family;
	u8 eff_model;
	u8 eff_stepping;
	u8 vrm_type;
};

#define ANY 0xFF

#ifdef CONFIG_X86

/* the stepping parameter is highest acceptable stepping for current line */

static struct vrm_model vrm_models[] = {
	{X86_VENDOR_AMD, 0x6, ANY, ANY, 90},		/* Athlon Duron etc */
	{X86_VENDOR_AMD, 0xF, ANY, ANY, 24},		/* Athlon 64, Opteron and above VRM 24 */
	{X86_VENDOR_INTEL, 0x6, 0x9, ANY, 13},		/* Pentium M (130 nm) */
	{X86_VENDOR_INTEL, 0x6, 0xB, ANY, 85},		/* Tualatin */
	{X86_VENDOR_INTEL, 0x6, 0xD, ANY, 13},		/* Pentium M (90 nm) */
	{X86_VENDOR_INTEL, 0x6, 0xE, ANY, 14},		/* Intel Core (65 nm) */
	{X86_VENDOR_INTEL, 0x6, 0xF, ANY, 110},		/* Intel Conroe */
	{X86_VENDOR_INTEL, 0x6, ANY, ANY, 82},		/* any P6 */
	{X86_VENDOR_INTEL, 0xF, 0x0, ANY, 90},		/* P4 */
	{X86_VENDOR_INTEL, 0xF, 0x1, ANY, 90},		/* P4 Willamette */
	{X86_VENDOR_INTEL, 0xF, 0x2, ANY, 90},		/* P4 Northwood */
	{X86_VENDOR_INTEL, 0xF, ANY, ANY, 100},		/* Prescott and above assume VRD 10 */
	{X86_VENDOR_CENTAUR, 0x6, 0x7, ANY, 85},	/* Eden ESP/Ezra */
	{X86_VENDOR_CENTAUR, 0x6, 0x8, 0x7, 85},	/* Ezra T */
	{X86_VENDOR_CENTAUR, 0x6, 0x9, 0x7, 85},	/* Nemiah */
	{X86_VENDOR_CENTAUR, 0x6, 0x9, ANY, 17},	/* C3-M, Eden-N */
	{X86_VENDOR_CENTAUR, 0x6, 0xA, 0x7, 0},		/* No information */
	{X86_VENDOR_CENTAUR, 0x6, 0xA, ANY, 13},	/* C7, Esther */
	{X86_VENDOR_UNKNOWN, ANY, ANY, ANY, 0}		/* stop here */
};

static u8 find_vrm(u8 eff_family, u8 eff_model, u8 eff_stepping, u8 vendor)
{
	int i = 0;

	while (vrm_models[i].vendor!=X86_VENDOR_UNKNOWN) {
		if (vrm_models[i].vendor==vendor)
			if ((vrm_models[i].eff_family==eff_family)
			 && ((vrm_models[i].eff_model==eff_model) ||
			     (vrm_models[i].eff_model==ANY)) &&
			     (eff_stepping <= vrm_models[i].eff_stepping))
				return vrm_models[i].vrm_type;
		i++;
	}

	return 0;
}

u8 vid_which_vrm(void)
{
	struct cpuinfo_x86 *c = cpu_data;
	u32 eax;
	u8 eff_family, eff_model, eff_stepping, vrm_ret;

	if (c->x86 < 6)		/* Any CPU with family lower than 6 */
		return 0;	/* doesn't have VID and/or CPUID */

	eax = cpuid_eax(1);
	eff_family = ((eax & 0x00000F00)>>8);
	eff_model  = ((eax & 0x000000F0)>>4);
	eff_stepping = eax & 0xF;
	if (eff_family == 0xF) {	/* use extended model & family */
		eff_family += ((eax & 0x00F00000)>>20);
		eff_model += ((eax & 0x000F0000)>>16)<<4;
	}
	vrm_ret = find_vrm(eff_family, eff_model, eff_stepping, c->x86_vendor);
	if (vrm_ret == 0)
		printk(KERN_INFO "hwmon-vid: Unknown VRM version of your "
		       "x86 CPU\n");
	return vrm_ret;
}

/* and now for something completely different for the non-x86 world */
#else
u8 vid_which_vrm(void)
{
	printk(KERN_INFO "hwmon-vid: Unknown VRM version of your CPU\n");
	return 0;
}
#endif

EXPORT_SYMBOL(vid_from_reg);
EXPORT_SYMBOL(vid_which_vrm);

MODULE_AUTHOR("Rudolf Marek <r.marek@assembler.cz>");

MODULE_DESCRIPTION("hwmon-vid driver");
MODULE_LICENSE("GPL");