/*

   * 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #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 Athlon 64 and AMD Opteron Processors, AMD Publication 26094,

   * http://support.amd.com/us/Processor_TechDocs/26094.PDF 

   * Table 74. VID Code Voltages
   * This corresponds to an arbitrary VRM code of 24 in the functions below.
   * These CPU models (K8 revision <= E) have 5 VID pins. See also:
   * Revision Guide for AMD Athlon 64 and AMD Opteron Processors, AMD Publication 25759,
   * http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/25759.pdf
   *
   * AMD NPT Family 0Fh Processors, AMD Publication 32559,

   * http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/32559.pdf
   * Table 71. VID Code Voltages

   * This corresponds to an arbitrary VRM code of 25 in the functions below.
   * These CPU models (K8 revision >= F) have 6 VID pins. See also:
   * Revision Guide for AMD NPT Family 0Fh Processors, AMD Publication 33610,
   * http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/33610.pdf

   *

   * 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:		/* Athlon64 & Opteron */
  		val &= 0x1f;
  		if (val == 0x1f)
  			return 0;
  				/* fall through */
  	case 25:		/* AMD NPT 0Fh */

  		val &= 0x3f;
  		return (val < 32) ? 1550 - 25 * val
  			: 775 - (25 * (val - 31)) / 2;

  
  	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:

  	case 131:

  		val &= 0x3f;

  		/* Exception for Eden ULV 500 MHz */
  		if (vrm == 131 && val == 0x3f)
  			val++;

  		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 */

  		if (vrm)

  			pr_warn("Requested unsupported VRM version (%u)
  ",
  				(unsigned int)vrm);

  		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.
   * The model match must be exact for 4-bit values. For model values 0x10
   * and above (extended model), all models below the parameter will match.
   */

  static struct vrm_model vrm_models[] = {

  	{X86_VENDOR_AMD, 0x6, ANY, ANY, 90},		/* Athlon Duron etc */

  	{X86_VENDOR_AMD, 0xF, 0x3F, ANY, 24},		/* Athlon 64, Opteron */

  	/* In theory, all NPT family 0Fh processors have 6 VID pins and should
  	   thus use vrm 25, however in practice not all mainboards route the
  	   6th VID pin because it is never needed. So we use the 5 VID pin
  	   variant (vrm 24) for the models which exist today. */
  	{X86_VENDOR_AMD, 0xF, 0x7F, ANY, 24},		/* NPT family 0Fh */
  	{X86_VENDOR_AMD, 0xF, ANY, ANY, 25},		/* future fam. 0Fh */

  	{X86_VENDOR_AMD, 0x10, ANY, ANY, 25},		/* NPT family 10h */

  	{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},	/* Nehemiah */

  	{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-M, C7, Eden (Esther) */
  	{X86_VENDOR_CENTAUR, 0x6, 0xD, ANY, 134},	/* C7-D, C7-M, C7, Eden (Esther) */

  	{X86_VENDOR_UNKNOWN, ANY, ANY, ANY, 0}		/* stop here */

  };

  /*
   * Special case for VIA model D: there are two different possible
   * VID tables, so we have to figure out first, which one must be
   * used. This resolves temporary drm value 134 to 14 (Intel Core
   * 7-bit VID), 13 (Pentium M 6-bit VID) or 131 (Pentium M 6-bit VID
   * + quirk for Eden ULV 500 MHz).
   * Note: something similar might be needed for model A, I'm not sure.
   */
  static u8 get_via_model_d_vrm(void)
  {
  	unsigned int vid, brand, dummy;
  	static const char *brands[4] = {
  		"C7-M", "C7", "Eden", "C7-D"
  	};
  
  	rdmsr(0x198, dummy, vid);
  	vid &= 0xff;
  
  	rdmsr(0x1154, brand, dummy);
  	brand = ((brand >> 4) ^ (brand >> 2)) & 0x03;
  
  	if (vid > 0x3f) {
  		pr_info("Using %d-bit VID table for VIA %s CPU
  ",
  			7, brands[brand]);
  		return 14;
  	} else {
  		pr_info("Using %d-bit VID table for VIA %s CPU
  ",
  			6, brands[brand]);
  		/* Enable quirk for Eden */
  		return brand == 2 ? 131 : 13;
  	}
  }

  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 >= 0x10 &&
  			      eff_model <= vrm_models[i].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(0);

  	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 == 134)
  		vrm_ret = get_via_model_d_vrm();

  	if (vrm_ret == 0)

  		pr_info("Unknown VRM version of your x86 CPU
  ");

  	return vrm_ret;
  }

  /* and now for something completely different for the non-x86 world */

  #else

  u8 vid_which_vrm(void)

  {

  	pr_info("Unknown VRM version of your CPU
  ");

  	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");