centaur.c

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/e820.h>
#include <asm/mtrr.h>
#include "cpu.h"

#ifdef CONFIG_X86_OOSTORE

static u32 __init power2(u32 x)
{
	u32 s=1;
	while(s<=x)
		s<<=1;
	return s>>=1;
}


/*
 *	Set up an actual MCR
 */
 
static void __init centaur_mcr_insert(int reg, u32 base, u32 size, int key)
{
	u32 lo, hi;
	
	hi = base & ~0xFFF;
	lo = ~(size-1);		/* Size is a power of 2 so this makes a mask */
	lo &= ~0xFFF;		/* Remove the ctrl value bits */
	lo |= key;		/* Attribute we wish to set */
	wrmsr(reg+MSR_IDT_MCR0, lo, hi);
	mtrr_centaur_report_mcr(reg, lo, hi);	/* Tell the mtrr driver */
}

/*
 *	Figure what we can cover with MCR's
 *
 *	Shortcut: We know you can't put 4Gig of RAM on a winchip
 */

static u32 __init ramtop(void)		/* 16388 */
{
	int i;
	u32 top = 0;
	u32 clip = 0xFFFFFFFFUL;
	
	for (i = 0; i < e820.nr_map; i++) {
		unsigned long start, end;

		if (e820.map[i].addr > 0xFFFFFFFFUL)
			continue;
		/*
		 *	Don't MCR over reserved space. Ignore the ISA hole
		 *	we frob around that catastrophy already
		 */
		 			
		if (e820.map[i].type == E820_RESERVED)
		{
			if(e820.map[i].addr >= 0x100000UL && e820.map[i].addr < clip)
				clip = e820.map[i].addr;
			continue;
		}
		start = e820.map[i].addr;
		end = e820.map[i].addr + e820.map[i].size;
		if (start >= end)
			continue;
		if (end > top)
			top = end;
	}
	/* Everything below 'top' should be RAM except for the ISA hole.
	   Because of the limited MCR's we want to map NV/ACPI into our
	   MCR range for gunk in RAM 
	   
	   Clip might cause us to MCR insufficient RAM but that is an
	   acceptable failure mode and should only bite obscure boxes with
	   a VESA hole at 15Mb
	   
	   The second case Clip sometimes kicks in is when the EBDA is marked
	   as reserved. Again we fail safe with reasonable results
	*/
	
	if(top>clip)
		top=clip;
		
	return top;
}

/*
 *	Compute a set of MCR's to give maximum coverage
 */

static int __init centaur_mcr_compute(int nr, int key)
{
	u32 mem = ramtop();
	u32 root = power2(mem);
	u32 base = root;
	u32 top = root;
	u32 floor = 0;
	int ct = 0;
	
	while(ct<nr)
	{
		u32 fspace = 0;

		/*
		 *	Find the largest block we will fill going upwards
		 */

		u32 high = power2(mem-top);	

		/*
		 *	Find the largest block we will fill going downwards
		 */

		u32 low = base/2;

		/*
		 *	Don't fill below 1Mb going downwards as there
		 *	is an ISA hole in the way.
		 */		
		 
		if(base <= 1024*1024)
			low = 0;
			
		/*
		 *	See how much space we could cover by filling below
		 *	the ISA hole
		 */
		 
		if(floor == 0)
			fspace = 512*1024;
		else if(floor ==512*1024)
			fspace = 128*1024;

		/* And forget ROM space */
		
		/*
		 *	Now install the largest coverage we get
		 */
		 
		if(fspace > high && fspace > low)
		{
			centaur_mcr_insert(ct, floor, fspace, key);
			floor += fspace;
		}
		else if(high > low)
		{
			centaur_mcr_insert(ct, top, high, key);
			top += high;
		}
		else if(low > 0)
		{
			base -= low;
			centaur_mcr_insert(ct, base, low, key);
		}
		else break;
		ct++;
	}
	/*
	 *	We loaded ct values. We now need to set the mask. The caller
	 *	must do this bit.
	 */
	 
	return ct;
}

static void __init centaur_create_optimal_mcr(void)
{
	int i;
	/*
	 *	Allocate up to 6 mcrs to mark as much of ram as possible
	 *	as write combining and weak write ordered.
	 *
	 *	To experiment with: Linux never uses stack operations for 
	 *	mmio spaces so we could globally enable stack operation wc
	 *
	 *	Load the registers with type 31 - full write combining, all
	 *	writes weakly ordered.
	 */
	int used = centaur_mcr_compute(6, 31);

	/*
	 *	Wipe unused MCRs
	 */
	 
	for(i=used;i<8;i++)
		wrmsr(MSR_IDT_MCR0+i, 0, 0);
}

static void __init winchip2_create_optimal_mcr(void)
{
	u32 lo, hi;
	int i;

	/*
	 *	Allocate up to 6 mcrs to mark as much of ram as possible
	 *	as write combining, weak store ordered.
	 *
	 *	Load the registers with type 25
	 *		8	-	weak write ordering
	 *		16	-	weak read ordering
	 *		1	-	write combining
	 */

	int used = centaur_mcr_compute(6, 25);
	
	/*
	 *	Mark the registers we are using.
	 */
	 
	rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
	for(i=0;i<used;i++)
		lo|=1<<(9+i);
	wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
	
	/*
	 *	Wipe unused MCRs
	 */
	 
	for(i=used;i<8;i++)
		wrmsr(MSR_IDT_MCR0+i, 0, 0);
}

/*
 *	Handle the MCR key on the Winchip 2.
 */

static void __init winchip2_unprotect_mcr(void)
{
	u32 lo, hi;
	u32 key;
	
	rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
	lo&=~0x1C0;	/* blank bits 8-6 */
	key = (lo>>17) & 7;
	lo |= key<<6;	/* replace with unlock key */
	wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
}

static void __init winchip2_protect_mcr(void)
{
	u32 lo, hi;
	
	rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
	lo&=~0x1C0;	/* blank bits 8-6 */
	wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
}
#endif /* CONFIG_X86_OOSTORE */

#define ACE_PRESENT	(1 << 6)
#define ACE_ENABLED	(1 << 7)
#define ACE_FCR		(1 << 28)	/* MSR_VIA_FCR */

#define RNG_PRESENT	(1 << 2)
#define RNG_ENABLED	(1 << 3)
#define RNG_ENABLE	(1 << 6)	/* MSR_VIA_RNG */

static void __init init_c3(struct cpuinfo_x86 *c)
{
	u32  lo, hi;

	/* Test for Centaur Extended Feature Flags presence */
	if (cpuid_eax(0xC0000000) >= 0xC0000001) {
		u32 tmp = cpuid_edx(0xC0000001);

		/* enable ACE unit, if present and disabled */
		if ((tmp & (ACE_PRESENT | ACE_ENABLED)) == ACE_PRESENT) {
			rdmsr (MSR_VIA_FCR, lo, hi);
			lo |= ACE_FCR;		/* enable ACE unit */
			wrmsr (MSR_VIA_FCR, lo, hi);
			printk(KERN_INFO "CPU: Enabled ACE h/w crypto\n");
		}

		/* enable RNG unit, if present and disabled */
		if ((tmp & (RNG_PRESENT | RNG_ENABLED)) == RNG_PRESENT) {
			rdmsr (MSR_VIA_RNG, lo, hi);
			lo |= RNG_ENABLE;	/* enable RNG unit */
			wrmsr (MSR_VIA_RNG, lo, hi);
			printk(KERN_INFO "CPU: Enabled h/w RNG\n");
		}

		/* store Centaur Extended Feature Flags as
		 * word 5 of the CPU capability bit array
		 */
		c->x86_capability[5] = cpuid_edx(0xC0000001);
	}

	/* Cyrix III family needs CX8 & PGE explicity enabled. */
	if (c->x86_model >=6 && c->x86_model <= 9) {
		rdmsr (MSR_VIA_FCR, lo, hi);
		lo |= (1<<1 | 1<<7);
		wrmsr (MSR_VIA_FCR, lo, hi);
		set_bit(X86_FEATURE_CX8, c->x86_capability);
	}

	/* Before Nehemiah, the C3's had 3dNOW! */
	if (c->x86_model >=6 && c->x86_model <9)
		set_bit(X86_FEATURE_3DNOW, c->x86_capability);

	get_model_name(c);
	display_cacheinfo(c);
}

static void __init init_centaur(struct cpuinfo_x86 *c)
{
	enum {
		ECX8=1<<1,
		EIERRINT=1<<2,
		DPM=1<<3,
		DMCE=1<<4,
		DSTPCLK=1<<5,
		ELINEAR=1<<6,
		DSMC=1<<7,
		DTLOCK=1<<8,
		EDCTLB=1<<8,
		EMMX=1<<9,
		DPDC=1<<11,
		EBRPRED=1<<12,
		DIC=1<<13,
		DDC=1<<14,
		DNA=1<<15,
		ERETSTK=1<<16,
		E2MMX=1<<19,
		EAMD3D=1<<20,
	};

	char *name;
	u32  fcr_set=0;
	u32  fcr_clr=0;
	u32  lo,hi,newlo;
	u32  aa,bb,cc,dd;

	/* Bit 31 in normal CPUID used for nonstandard 3DNow ID;
	   3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway */
	clear_bit(0*32+31, c->x86_capability);

	switch (c->x86) {

		case 5:
			switch(c->x86_model) {
			case 4:
				name="C6";
				fcr_set=ECX8|DSMC|EDCTLB|EMMX|ERETSTK;
				fcr_clr=DPDC;
				printk(KERN_NOTICE "Disabling bugged TSC.\n");
				clear_bit(X86_FEATURE_TSC, c->x86_capability);
#ifdef CONFIG_X86_OOSTORE
				centaur_create_optimal_mcr();
				/* Enable
					write combining on non-stack, non-string
					write combining on string, all types
					weak write ordering 
					
				   The C6 original lacks weak read order 
				   
				   Note 0x120 is write only on Winchip 1 */
				   
				wrmsr(MSR_IDT_MCR_CTRL, 0x01F0001F, 0);
#endif				
				break;
			case 8:
				switch(c->x86_mask) {
				default:
					name="2";
					break;
				case 7 ... 9:
					name="2A";
					break;
				case 10 ... 15:
					name="2B";
					break;
				}
				fcr_set=ECX8|DSMC|DTLOCK|EMMX|EBRPRED|ERETSTK|E2MMX|EAMD3D;
				fcr_clr=DPDC;
#ifdef CONFIG_X86_OOSTORE
				winchip2_unprotect_mcr();
				winchip2_create_optimal_mcr();
				rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
				/* Enable
					write combining on non-stack, non-string
					write combining on string, all types
					weak write ordering 
				*/
				lo|=31;				
				wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
				winchip2_protect_mcr();
#endif
				break;
			case 9:
				name="3";
				fcr_set=ECX8|DSMC|DTLOCK|EMMX|EBRPRED|ERETSTK|E2MMX|EAMD3D;
				fcr_clr=DPDC;
#ifdef CONFIG_X86_OOSTORE
				winchip2_unprotect_mcr();
				winchip2_create_optimal_mcr();
				rdmsr(MSR_IDT_MCR_CTRL, lo, hi);
				/* Enable
					write combining on non-stack, non-string
					write combining on string, all types
					weak write ordering 
				*/
				lo|=31;				
				wrmsr(MSR_IDT_MCR_CTRL, lo, hi);
				winchip2_protect_mcr();
#endif
				break;
			default:
				name="??";
			}

			rdmsr(MSR_IDT_FCR1, lo, hi);
			newlo=(lo|fcr_set) & (~fcr_clr);

			if (newlo!=lo) {
				printk(KERN_INFO "Centaur FCR was 0x%X now 0x%X\n", lo, newlo );
				wrmsr(MSR_IDT_FCR1, newlo, hi );
			} else {
				printk(KERN_INFO "Centaur FCR is 0x%X\n",lo);
			}
			/* Emulate MTRRs using Centaur's MCR. */
			set_bit(X86_FEATURE_CENTAUR_MCR, c->x86_capability);
			/* Report CX8 */
			set_bit(X86_FEATURE_CX8, c->x86_capability);
			/* Set 3DNow! on Winchip 2 and above. */
			if (c->x86_model >=8)
				set_bit(X86_FEATURE_3DNOW, c->x86_capability);
			/* See if we can find out some more. */
			if ( cpuid_eax(0x80000000) >= 0x80000005 ) {
				/* Yes, we can. */
				cpuid(0x80000005,&aa,&bb,&cc,&dd);
				/* Add L1 data and code cache sizes. */
				c->x86_cache_size = (cc>>24)+(dd>>24);
			}
			sprintf( c->x86_model_id, "WinChip %s", name );
			break;

		case 6:
			init_c3(c);
			break;
	}
}

static unsigned int centaur_size_cache(struct cpuinfo_x86 * c, unsigned int size)
{
	/* VIA C3 CPUs (670-68F) need further shifting. */
	if ((c->x86 == 6) && ((c->x86_model == 7) || (c->x86_model == 8)))
		size >>= 8;

	/* VIA also screwed up Nehemiah stepping 1, and made
	   it return '65KB' instead of '64KB'
	   - Note, it seems this may only be in engineering samples. */
	if ((c->x86==6) && (c->x86_model==9) && (c->x86_mask==1) && (size==65))
		size -=1;

	return size;
}

static struct cpu_dev centaur_cpu_dev __initdata = {
	.c_vendor	= "Centaur",
	.c_ident	= { "CentaurHauls" },
	.c_init		= init_centaur,
	.c_size_cache	= centaur_size_cache,
};

int __init centaur_init_cpu(void)
{
	cpu_devs[X86_VENDOR_CENTAUR] = &centaur_cpu_dev;
	return 0;
}

//early_arch_initcall(centaur_init_cpu);

static int __init centaur_exit_cpu(void)
{
	cpu_devs[X86_VENDOR_CENTAUR] = NULL;
	return 0;
}

late_initcall(centaur_exit_cpu);