src/northbridge/intel/gm45/pm.c - coreboot - Gitiles

 /* SPDX-License-Identifier: GPL-2.0-only */

 #include <stdint.h>
 #include <device/pci_def.h>
 #include <cpu/x86/msr.h>
 #include <cpu/intel/speedstep.h>

 #include "gm45.h"

 static int sku_freq_index(const gmch_gfx_t sku, const int low_power_mode)
 {
 	if (low_power_mode)
 		return 1;
 	switch (sku) {
 	case GMCH_GM45:
 	case GMCH_GE45:
 	case GMCH_GS45:
 		return 0;
 	case GMCH_GM47:
 		return 2;
 	case GMCH_GM49:
 		return 3;
 	default:
 		return 0;
 	}
 }
 static void init_freq_scaling(const gmch_gfx_t sku, const int low_power_mode)
 {
 	int i;

 	mchbar_clrsetbits32(0x11cc, 0x1f, 0x17);
 	switch (sku) {
 	case GMCH_GM45:
 	case GMCH_GE45:
 	case GMCH_GS45:
 	case GMCH_GM47:
 	case GMCH_GM49:
 		break;
 	default:
 		/* No more to be done for the others. */
 		return;
 	}

 	static const u32 voltage_mask =
 		(0x1f << 24) | (0x1f << 16) | (0x1f << 8) | 0x1f;
 	mchbar_clrsetbits32(0x1120, voltage_mask, 0x10111213);
 	mchbar_clrsetbits32(0x1124, voltage_mask, 0x14151617);
 	mchbar_clrsetbits32(0x1128, voltage_mask, 0x18191a1b);
 	mchbar_clrsetbits32(0x112c, voltage_mask, 0x1c1d1e1f);
 	mchbar_clrsetbits32(0x1130, voltage_mask, 0x00010203);
 	mchbar_clrsetbits32(0x1134, voltage_mask, 0x04050607);
 	mchbar_clrsetbits32(0x1138, voltage_mask, 0x08090a0b);
 	mchbar_clrsetbits32(0x113c, voltage_mask, 0x0c0d0e0f);

 	/* Program frequencies. */
 	static const u32 frequencies_from_sku_vco[][4][8] = {
 	/* GM45/GE45/GS45_perf */ {
 	    /* VCO 2666 */ { 0xcd, 0xbc, 0x9b, 0x8a, 0x79, 0x78, 0x67, 0x56 },
 	    /* VCO 3200 */ { 0xcd, 0xac, 0x9b, 0x8a, 0x89, 0x78, 0x67, 0x56 },
 	    /* VCO 4000 */ { 0xac, 0x9b, 0x9a, 0x89, 0x89, 0x68, 0x56, 0x45 },
 	    /* VCO 5333 */ { 0xab, 0x9a, 0x79, 0x68, 0x57, 0x56, 0x45, 0x34 },
 	},
 	/* GS45_low_power */ {
 	    /* VCO 2666 */ { 0xcd, 0x8a },
 	    /* VCO 3200 */ { 0xcd, 0x89 },
 	    /* VCO 4000 */ { 0xac, 0x89 },
 	    /* VCO 5333 */ { 0xab, 0x68 },
 	},
 	/* GM47 */ {
 	    /* VCO 2666 */ { 0xcd, 0xcd, 0xbc, 0x9b, 0x79, 0x78, 0x67, 0x56 },
 	    /* VCO 3200 */ { 0xde, 0xcd, 0xac, 0x9b, 0x89, 0x78, 0x67, 0x56 },
 	    /* VCO 4000 */ { 0xcd, 0xac, 0x9b, 0x9a, 0x89, 0x68, 0x56, 0x45 },
 	    /* VCO 5333 */ { 0xac, 0xab, 0x9a, 0x79, 0x68, 0x56, 0x45, 0x34 },
 	},
 	/* GM49 */ {
 	    /* VCO 2666 */ { },
 	    /* VCO 3200 */ { 0xef, 0xde, 0xcd, 0xac, 0x89, 0x78, 0x67, 0x56 },
 	    /* VCO 4000 */ { 0xef, 0xde, 0xac, 0x9b, 0x89, 0x68, 0x56, 0x45 },
 	    /* VCO 5333 */ { 0xce, 0xbd, 0xab, 0x9a, 0x68, 0x57, 0x45, 0x34 },
 	}};
 	const int sku_index = sku_freq_index(sku, low_power_mode);
 	const int vco_index = raminit_read_vco_index();
 	const int reg_limit = low_power_mode ? 1 : 4;
 	if (sku == GMCH_GM49)
 		mchbar_write8(0x1110 + 3, 0x1b);
 	else
 		mchbar_write8(0x1110 + 3, 0x17);
 	mchbar_write8(0x1110 + 1, 0x17);
 	if (!low_power_mode) {
 		mchbar_write8(0x1114 + 3, 0x17);
 		mchbar_write8(0x1114 + 1, 0x17);
 		mchbar_write8(0x1118 + 3, 0x17);
 		mchbar_write8(0x1118 + 1, 0x17);
 		mchbar_write8(0x111c + 3, 0x17);
 		mchbar_write8(0x111c + 1, 0x17);
 	}
 	for (i = 0; i < reg_limit; ++i) {
 		const int mchbar = 0x1110 + (i * 4);
 		mchbar_write8(mchbar + 2, frequencies_from_sku_vco
 					[sku_index][vco_index][i * 2 + 0]);
 		mchbar_write8(mchbar + 0, frequencies_from_sku_vco
 					[sku_index][vco_index][i * 2 + 1]);
 	}

 	if (low_power_mode) {
 		mchbar_clrsetbits16(0x1190, 7 << 8 | 7 << 4 | 7, 1 << 8 | 1 << 4 | 1);
 	} else {
 		mchbar_clrsetbits16(0x1190, 7 << 8 | 7 << 4, 7);
 		if (sku == GMCH_GS45) /* performance mode */
 			mchbar_clrbits32(0x0ffc, 1 << 31);
 	}

 	mchbar_setbits16(0x0fc0, 1 << 11);
 	mchbar_write16(0x11b8, 0x333c);
 	mchbar_write16(0x11c0 + 2, 0x0303);
 	mchbar_write32(0x11c4, 0x0a030a03);
 	mchbar_clrsetbits16(0x1100, 0x1f << 8, 3 << 8);
 	mchbar_write16(0x11b8 + 2, 0x4000);
 }

 void init_pm(const sysinfo_t *const sysinfo, int do_freq_scaling_cfg)
 {
 	const stepping_t stepping = sysinfo->stepping;
 	const fsb_clock_t fsb = sysinfo->selected_timings.fsb_clock;
 	const mem_clock_t memclk = sysinfo->selected_timings.mem_clock;

 	mchbar_write16(0xc14, 0);
 	mchbar_write16(0xc20, 0);
 	mchbar_write32(0xfc0, 0x001f00fd);
 	mchbar_setbits32(0xfc0, 3 << 25);
 	mchbar_setbits32(0xfc0, 1 << 11);
 	mchbar_write8(0xfb0, 3);
 	mchbar_setbits8(0xf10, 1 << 1);
 	if (fsb == FSB_CLOCK_667MHz) {
 		mchbar_write16(0xc3a, 0x0ea6);
 		mchbar_clrsetbits8(0xc16, 0x7f, 0x0e);
 	} else if (fsb == FSB_CLOCK_800MHz) {
 		mchbar_write16(0xc3a, 0x1194);
 		mchbar_clrsetbits8(0xc16, 0x7f, 0x10);
 	} else if (fsb == FSB_CLOCK_1067MHz) {
 		mchbar_write16(0xc3a, 0x1777);
 		mchbar_clrsetbits8(0xc16, 0x7f, 0x15);
 	}
 	mchbar_write8(0xfb8, 3);
 	if (fsb == FSB_CLOCK_667MHz)
 		mchbar_write16(0xc38, 0x0ea6);
 	else if (fsb == FSB_CLOCK_800MHz)
 		mchbar_write16(0xc38, 0x1194);
 	else if (fsb == FSB_CLOCK_1067MHz)
 		mchbar_write16(0xc38, 0x1777);
 	mchbar_setbits8(0xf10, 1 << 5);
 	mchbar_setbits16(0xc16, 3 << 12);
 	mchbar_write32(0xf60, 0x01030419);
 	if (fsb == FSB_CLOCK_667MHz) {
 		mchbar_write32(0xf00, 0x00000600);
 		mchbar_write32(0xf04, 0x00001d80);
 	} else if (fsb == FSB_CLOCK_800MHz) {
 		mchbar_write32(0xf00, 0x00000700);
 		mchbar_write32(0xf04, 0x00002380);
 	} else if (fsb == FSB_CLOCK_1067MHz) {
 		mchbar_write32(0xf00, 0x00000900);
 		mchbar_write32(0xf04, 0x00002e80);
 	}
 	mchbar_write16(0xf08, 0x730f);
 	if (fsb == FSB_CLOCK_667MHz)
 		mchbar_write16(0xf0c, 0x0b96);
 	else if (fsb == FSB_CLOCK_800MHz)
 		mchbar_write16(0xf0c, 0x0c99);
 	else if (fsb == FSB_CLOCK_1067MHz)
 		mchbar_write16(0xf0c, 0x10a4);
 	mchbar_setbits32(0xf80, 1 << 31);

 	mchbar_write32(0x40, (mchbar_read32(0x40) & ~(0x3f << 24)) |
 		       ((sysinfo->cores == 4) ? (1 << 24) : 0));

 	mchbar_clrbits32(0x40, 1 << 19);
 	mchbar_setbits32(0x40, 1 << 13);
 	mchbar_setbits32(0x40, 1 << 21);
 	mchbar_setbits32(0x40, 1 << 9);
 	if (stepping > STEPPING_B1) {
 		if (fsb != FSB_CLOCK_1067MHz) {
 			mchbar_setbits32(0x70, 1 << 30);
 		} else {
 			mchbar_clrbits32(0x70, 1 << 30);
 		}
 	}
 	if (stepping < STEPPING_B1)
 		mchbar_setbits32(0x70, 1 << 29);
 	else
 		mchbar_clrbits32(0x70, 1 << 29);
 	if (stepping > STEPPING_B1) {
 		mchbar_setbits32(0x70, 1 << 28);
 		mchbar_setbits32(0x70, 1 << 25);
 	}
 	if (stepping > STEPPING_B0) {
 		if (fsb != FSB_CLOCK_667MHz)
 			mchbar_clrsetbits32(0x70, 3 << 21, 1 << 21);
 		else
 			mchbar_clrbits32(0x70, 3 << 21);
 	}
 	if (stepping > STEPPING_B2)
 		mchbar_setbits32(0x44, 1 << 30);
 	mchbar_setbits32(0x44, 1 << 31);
 	if (sysinfo->cores == 2)
 		mchbar_setbits32(0x44, 1 << 26);
 	mchbar_setbits32(0x44, 1 << 21);
 	mchbar_clrsetbits32(0x44, 3 << 24, 2 << 24);
 	mchbar_setbits32(0x44, 1 << 5);
 	mchbar_setbits32(0x44, 1 << 4);
 	mchbar_clrsetbits32(0x90, 7, 4);
 	mchbar_setbits32(0x94, 1 << 29);
 	mchbar_setbits32(0x94, 1 << 11);
 	if (stepping < STEPPING_B0)
 		mchbar_clrsetbits32(0x94, 3 << 19, 2 << 19);
 	if (stepping > STEPPING_B2)
 		mchbar_setbits32(0x94, 1 << 21);
 	mchbar_clrbits8(0xb00, 1 << 0);
 	mchbar_setbits8(0xb00, 1 << 7);
 	if (fsb != FSB_CLOCK_1067MHz)
 		mchbar_setbits8(0x75, 1 << 6);
 	else
 		mchbar_clrbits8(0x75, ~(1 << 1));
 	mchbar_setbits8(0x77, 3);
 	if (stepping >= STEPPING_B1)
 		mchbar_setbits8(0x77, 1 << 2);
 	if (stepping > STEPPING_B2)
 		mchbar_setbits8(0x77, 1 << 4);
 	if (mchbar_read16(0x90) & (1 << 8))
 		mchbar_clrbits8(0x90, 7 << 4);
 	if (stepping >= STEPPING_B0)
 		mchbar_setbits8(0xd0, 1 << 1);
 	mchbar_setbits8(0xbd8, 3 << 2);
 	if (stepping >= STEPPING_B3)
 		mchbar_setbits32(0x70, 1 << 0);
 	mchbar_setbits32(0x70, 1 << 3);
 	if (stepping >= STEPPING_B0)
 		mchbar_clrbits32(0x70, 1 << 16);
 	else
 		mchbar_setbits32(0x70, 1 << 16);
 	if (stepping >= STEPPING_B3)
 		mchbar_setbits8(0xc14, 1 << 1);
 	if (stepping >= STEPPING_B1)
 		mchbar_clrsetbits16(0xffc, 0x7ff, 0x7c0);
 	mchbar_clrsetbits16(0x48, 0xff << 2, 0xaa << 2);
 	if (stepping == STEPPING_CONVERSION_A1) {
 		mchbar_setbits16(0x40, 1 << 12);
 		mchbar_setbits32(0x94, 3 << 22);
 	}

 	const int cpu_supports_super_lfm =
 				rdmsr(MSR_EXTENDED_CONFIG).lo & (1 << 27);
 	if ((stepping >= STEPPING_B0) && cpu_supports_super_lfm) {
 		mchbar_clrbits16(CLKCFG_MCHBAR, 1 << 7);
 		mchbar_setbits16(CLKCFG_MCHBAR, 1 << 14);
 	} else {
 		mchbar_clrbits16(CLKCFG_MCHBAR, 1 << 14);
 		mchbar_setbits16(CLKCFG_MCHBAR, 1 << 7);
 		mchbar_clrbits32(0x44, 1 << 31); /* Was set above. */
 	}

 	if ((sysinfo->gfx_type != GMCH_PM45) && do_freq_scaling_cfg &&
 			(sysinfo->gfx_type != GMCH_UNKNOWN))
 		init_freq_scaling(sysinfo->gfx_type,
 				  sysinfo->gs45_low_power_mode);

 	/* This has to be the last write to CLKCFG. */
 	if ((fsb == FSB_CLOCK_1067MHz) && (memclk == MEM_CLOCK_667MT))
 		mchbar_clrbits32(CLKCFG_MCHBAR, 1 << 17);
 }
	/* SPDX-License-Identifier: GPL-2.0-only */

	#include <stdint.h>
	#include <device/pci_def.h>
	#include <cpu/x86/msr.h>
	#include <cpu/intel/speedstep.h>

	#include "gm45.h"

	static int sku_freq_index(const gmch_gfx_t sku, const int low_power_mode)
	{
	if (low_power_mode)
	return 1;
	switch (sku) {
	case GMCH_GM45:
	case GMCH_GE45:
	case GMCH_GS45:
	return 0;
	case GMCH_GM47:
	return 2;
	case GMCH_GM49:
	return 3;
	default:
	return 0;
	}
	}
	static void init_freq_scaling(const gmch_gfx_t sku, const int low_power_mode)
	{
	int i;

	mchbar_clrsetbits32(0x11cc, 0x1f, 0x17);
	switch (sku) {
	case GMCH_GM45:
	case GMCH_GE45:
	case GMCH_GS45:
	case GMCH_GM47:
	case GMCH_GM49:
	break;
	default:
	/* No more to be done for the others. */
	return;
	}

	static const u32 voltage_mask =
	(0x1f << 24) \| (0x1f << 16) \| (0x1f << 8) \| 0x1f;
	mchbar_clrsetbits32(0x1120, voltage_mask, 0x10111213);
	mchbar_clrsetbits32(0x1124, voltage_mask, 0x14151617);
	mchbar_clrsetbits32(0x1128, voltage_mask, 0x18191a1b);
	mchbar_clrsetbits32(0x112c, voltage_mask, 0x1c1d1e1f);
	mchbar_clrsetbits32(0x1130, voltage_mask, 0x00010203);
	mchbar_clrsetbits32(0x1134, voltage_mask, 0x04050607);
	mchbar_clrsetbits32(0x1138, voltage_mask, 0x08090a0b);
	mchbar_clrsetbits32(0x113c, voltage_mask, 0x0c0d0e0f);

	/* Program frequencies. */
	static const u32 frequencies_from_sku_vco[][4][8] = {
	/* GM45/GE45/GS45_perf */ {
	/* VCO 2666 */ { 0xcd, 0xbc, 0x9b, 0x8a, 0x79, 0x78, 0x67, 0x56 },
	/* VCO 3200 */ { 0xcd, 0xac, 0x9b, 0x8a, 0x89, 0x78, 0x67, 0x56 },
	/* VCO 4000 */ { 0xac, 0x9b, 0x9a, 0x89, 0x89, 0x68, 0x56, 0x45 },
	/* VCO 5333 */ { 0xab, 0x9a, 0x79, 0x68, 0x57, 0x56, 0x45, 0x34 },
	},
	/* GS45_low_power */ {
	/* VCO 2666 */ { 0xcd, 0x8a },
	/* VCO 3200 */ { 0xcd, 0x89 },
	/* VCO 4000 */ { 0xac, 0x89 },
	/* VCO 5333 */ { 0xab, 0x68 },
	},
	/* GM47 */ {
	/* VCO 2666 */ { 0xcd, 0xcd, 0xbc, 0x9b, 0x79, 0x78, 0x67, 0x56 },
	/* VCO 3200 */ { 0xde, 0xcd, 0xac, 0x9b, 0x89, 0x78, 0x67, 0x56 },
	/* VCO 4000 */ { 0xcd, 0xac, 0x9b, 0x9a, 0x89, 0x68, 0x56, 0x45 },
	/* VCO 5333 */ { 0xac, 0xab, 0x9a, 0x79, 0x68, 0x56, 0x45, 0x34 },
	},
	/* GM49 */ {
	/* VCO 2666 */ { },
	/* VCO 3200 */ { 0xef, 0xde, 0xcd, 0xac, 0x89, 0x78, 0x67, 0x56 },
	/* VCO 4000 */ { 0xef, 0xde, 0xac, 0x9b, 0x89, 0x68, 0x56, 0x45 },
	/* VCO 5333 */ { 0xce, 0xbd, 0xab, 0x9a, 0x68, 0x57, 0x45, 0x34 },
	}};
	const int sku_index = sku_freq_index(sku, low_power_mode);
	const int vco_index = raminit_read_vco_index();
	const int reg_limit = low_power_mode ? 1 : 4;
	if (sku == GMCH_GM49)
	mchbar_write8(0x1110 + 3, 0x1b);
	else
	mchbar_write8(0x1110 + 3, 0x17);
	mchbar_write8(0x1110 + 1, 0x17);
	if (!low_power_mode) {
	mchbar_write8(0x1114 + 3, 0x17);
	mchbar_write8(0x1114 + 1, 0x17);
	mchbar_write8(0x1118 + 3, 0x17);
	mchbar_write8(0x1118 + 1, 0x17);
	mchbar_write8(0x111c + 3, 0x17);
	mchbar_write8(0x111c + 1, 0x17);
	}
	for (i = 0; i < reg_limit; ++i) {
	const int mchbar = 0x1110 + (i * 4);
	mchbar_write8(mchbar + 2, frequencies_from_sku_vco
	[sku_index][vco_index][i * 2 + 0]);
	mchbar_write8(mchbar + 0, frequencies_from_sku_vco
	[sku_index][vco_index][i * 2 + 1]);
	}

	if (low_power_mode) {
	mchbar_clrsetbits16(0x1190, 7 << 8 \| 7 << 4 \| 7, 1 << 8 \| 1 << 4 \| 1);
	} else {
	mchbar_clrsetbits16(0x1190, 7 << 8 \| 7 << 4, 7);
	if (sku == GMCH_GS45) /* performance mode */
	mchbar_clrbits32(0x0ffc, 1 << 31);
	}

	mchbar_setbits16(0x0fc0, 1 << 11);
	mchbar_write16(0x11b8, 0x333c);
	mchbar_write16(0x11c0 + 2, 0x0303);
	mchbar_write32(0x11c4, 0x0a030a03);
	mchbar_clrsetbits16(0x1100, 0x1f << 8, 3 << 8);
	mchbar_write16(0x11b8 + 2, 0x4000);
	}

	void init_pm(const sysinfo_t *const sysinfo, int do_freq_scaling_cfg)
	{
	const stepping_t stepping = sysinfo->stepping;
	const fsb_clock_t fsb = sysinfo->selected_timings.fsb_clock;
	const mem_clock_t memclk = sysinfo->selected_timings.mem_clock;

	mchbar_write16(0xc14, 0);
	mchbar_write16(0xc20, 0);
	mchbar_write32(0xfc0, 0x001f00fd);
	mchbar_setbits32(0xfc0, 3 << 25);
	mchbar_setbits32(0xfc0, 1 << 11);
	mchbar_write8(0xfb0, 3);
	mchbar_setbits8(0xf10, 1 << 1);
	if (fsb == FSB_CLOCK_667MHz) {
	mchbar_write16(0xc3a, 0x0ea6);
	mchbar_clrsetbits8(0xc16, 0x7f, 0x0e);
	} else if (fsb == FSB_CLOCK_800MHz) {
	mchbar_write16(0xc3a, 0x1194);
	mchbar_clrsetbits8(0xc16, 0x7f, 0x10);
	} else if (fsb == FSB_CLOCK_1067MHz) {
	mchbar_write16(0xc3a, 0x1777);
	mchbar_clrsetbits8(0xc16, 0x7f, 0x15);
	}
	mchbar_write8(0xfb8, 3);
	if (fsb == FSB_CLOCK_667MHz)
	mchbar_write16(0xc38, 0x0ea6);
	else if (fsb == FSB_CLOCK_800MHz)
	mchbar_write16(0xc38, 0x1194);
	else if (fsb == FSB_CLOCK_1067MHz)
	mchbar_write16(0xc38, 0x1777);
	mchbar_setbits8(0xf10, 1 << 5);
	mchbar_setbits16(0xc16, 3 << 12);
	mchbar_write32(0xf60, 0x01030419);
	if (fsb == FSB_CLOCK_667MHz) {
	mchbar_write32(0xf00, 0x00000600);
	mchbar_write32(0xf04, 0x00001d80);
	} else if (fsb == FSB_CLOCK_800MHz) {
	mchbar_write32(0xf00, 0x00000700);
	mchbar_write32(0xf04, 0x00002380);
	} else if (fsb == FSB_CLOCK_1067MHz) {
	mchbar_write32(0xf00, 0x00000900);
	mchbar_write32(0xf04, 0x00002e80);
	}
	mchbar_write16(0xf08, 0x730f);
	if (fsb == FSB_CLOCK_667MHz)
	mchbar_write16(0xf0c, 0x0b96);
	else if (fsb == FSB_CLOCK_800MHz)
	mchbar_write16(0xf0c, 0x0c99);
	else if (fsb == FSB_CLOCK_1067MHz)
	mchbar_write16(0xf0c, 0x10a4);
	mchbar_setbits32(0xf80, 1 << 31);

	mchbar_write32(0x40, (mchbar_read32(0x40) & ~(0x3f << 24)) \|
	((sysinfo->cores == 4) ? (1 << 24) : 0));

	mchbar_clrbits32(0x40, 1 << 19);
	mchbar_setbits32(0x40, 1 << 13);
	mchbar_setbits32(0x40, 1 << 21);
	mchbar_setbits32(0x40, 1 << 9);
	if (stepping > STEPPING_B1) {
	if (fsb != FSB_CLOCK_1067MHz) {
	mchbar_setbits32(0x70, 1 << 30);
	} else {
	mchbar_clrbits32(0x70, 1 << 30);
	}
	}
	if (stepping < STEPPING_B1)
	mchbar_setbits32(0x70, 1 << 29);
	else
	mchbar_clrbits32(0x70, 1 << 29);
	if (stepping > STEPPING_B1) {
	mchbar_setbits32(0x70, 1 << 28);
	mchbar_setbits32(0x70, 1 << 25);
	}
	if (stepping > STEPPING_B0) {
	if (fsb != FSB_CLOCK_667MHz)
	mchbar_clrsetbits32(0x70, 3 << 21, 1 << 21);
	else
	mchbar_clrbits32(0x70, 3 << 21);
	}
	if (stepping > STEPPING_B2)
	mchbar_setbits32(0x44, 1 << 30);
	mchbar_setbits32(0x44, 1 << 31);
	if (sysinfo->cores == 2)
	mchbar_setbits32(0x44, 1 << 26);
	mchbar_setbits32(0x44, 1 << 21);
	mchbar_clrsetbits32(0x44, 3 << 24, 2 << 24);
	mchbar_setbits32(0x44, 1 << 5);
	mchbar_setbits32(0x44, 1 << 4);
	mchbar_clrsetbits32(0x90, 7, 4);
	mchbar_setbits32(0x94, 1 << 29);
	mchbar_setbits32(0x94, 1 << 11);
	if (stepping < STEPPING_B0)
	mchbar_clrsetbits32(0x94, 3 << 19, 2 << 19);
	if (stepping > STEPPING_B2)
	mchbar_setbits32(0x94, 1 << 21);
	mchbar_clrbits8(0xb00, 1 << 0);
	mchbar_setbits8(0xb00, 1 << 7);
	if (fsb != FSB_CLOCK_1067MHz)
	mchbar_setbits8(0x75, 1 << 6);
	else
	mchbar_clrbits8(0x75, ~(1 << 1));
	mchbar_setbits8(0x77, 3);
	if (stepping >= STEPPING_B1)
	mchbar_setbits8(0x77, 1 << 2);
	if (stepping > STEPPING_B2)
	mchbar_setbits8(0x77, 1 << 4);
	if (mchbar_read16(0x90) & (1 << 8))
	mchbar_clrbits8(0x90, 7 << 4);
	if (stepping >= STEPPING_B0)
	mchbar_setbits8(0xd0, 1 << 1);
	mchbar_setbits8(0xbd8, 3 << 2);
	if (stepping >= STEPPING_B3)
	mchbar_setbits32(0x70, 1 << 0);
	mchbar_setbits32(0x70, 1 << 3);
	if (stepping >= STEPPING_B0)
	mchbar_clrbits32(0x70, 1 << 16);
	else
	mchbar_setbits32(0x70, 1 << 16);
	if (stepping >= STEPPING_B3)
	mchbar_setbits8(0xc14, 1 << 1);
	if (stepping >= STEPPING_B1)
	mchbar_clrsetbits16(0xffc, 0x7ff, 0x7c0);
	mchbar_clrsetbits16(0x48, 0xff << 2, 0xaa << 2);
	if (stepping == STEPPING_CONVERSION_A1) {
	mchbar_setbits16(0x40, 1 << 12);
	mchbar_setbits32(0x94, 3 << 22);
	}

	const int cpu_supports_super_lfm =
	rdmsr(MSR_EXTENDED_CONFIG).lo & (1 << 27);
	if ((stepping >= STEPPING_B0) && cpu_supports_super_lfm) {
	mchbar_clrbits16(CLKCFG_MCHBAR, 1 << 7);
	mchbar_setbits16(CLKCFG_MCHBAR, 1 << 14);
	} else {
	mchbar_clrbits16(CLKCFG_MCHBAR, 1 << 14);
	mchbar_setbits16(CLKCFG_MCHBAR, 1 << 7);
	mchbar_clrbits32(0x44, 1 << 31); /* Was set above. */
	}

	if ((sysinfo->gfx_type != GMCH_PM45) && do_freq_scaling_cfg &&
	(sysinfo->gfx_type != GMCH_UNKNOWN))
	init_freq_scaling(sysinfo->gfx_type,
	sysinfo->gs45_low_power_mode);

	/* This has to be the last write to CLKCFG. */
	if ((fsb == FSB_CLOCK_1067MHz) && (memclk == MEM_CLOCK_667MT))
	mchbar_clrbits32(CLKCFG_MCHBAR, 1 << 17);
	}