shithub: purgatorio

ref: a5cb451b299b03f44154fac5780b6a57ca130ce0
dir: /os/sa1110/mmu.c/

#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"

/*
 * return physical address corresponding to a given virtual address,
 * or 0 if there is no such address
 */
ulong
va2pa(void *v)
{
	int idx;
	ulong pte, ste, *ttb;

	idx = MmuL1x((ulong)v);
	ttb = (ulong*)KTTB;
	ste = ttb[idx];
	switch(ste & MmuL1type) {
	case MmuL1section:
		return MmuSBA(ste)|((ulong)v & 0x000fffff);
	case MmuL1page:
		pte = ((ulong *)MmuPTBA(ste))[MmuL2x((ulong)v)]; 
		switch(pte & 3) {
		case MmuL2large:
			return (pte & 0xffff0000)|((ulong)v & 0x0000ffff);
		case MmuL2small:
			return (pte & 0xfffff000)|((ulong)v & 0x00000fff);
		}
	}
	return 0;
}

enum {
	SectionPages = MmuSection/MmuSmallPage,
	PtAlign = 1<<10,

	MINICACHED = 0x10000000,
};

/* for debugging */
void
prs(char *s)
{
	for(; *s; s++)
		uartputc(*s);
}

void
pr16(ulong n)
{
	int i;

	for(i=28; i>=0; i-=4)
		uartputc("0123456789ABCDEF"[(n>>i)&0xF]);
}

void*
mmuphysmap(ulong phys, ulong)
{
	ulong *ttb;
	void *va;

	ttb = (ulong*)KTTB;
	va = KADDR(phys);
	ttb[MmuL1x((ulong)va)] = phys | 0xC10 | MmuL1section;
	return va;
}

/*
 * Set a 1-1 map of virtual to physical memory, except:
 *	doubly-map page0 at the alternative interrupt vector address,
 * 	doubly-map physical memory at KZERO+256*MB as uncached but buffered, and
 *	disable access to 0 (nil pointers).
 */
void
mmuinit(void)
{
	int i;
	ulong *ttb, *ptable, va;

	ttb = (ulong*)KTTB;
	for(i=0; i<MmuL1x(0x10000000); i++)
		ttb[i] = 0;
	for(; i < 0x1000; i++)
		ttb[i] = (i<<20) | 0xC10 | MmuL1section;
	for(va = KZERO; va < KZERO+64*MB; va += MB)
		ttb[MmuL1x(va)] |= MmuWB | MmuIDC;	/* DRAM is cacheable */
	for(i = 0; i < 64*MB; i += MB)
		ttb[MmuL1x(UCDRAMZERO+i)] = (PHYSMEM0+i) | 0xC10 | MmuL1section;
	/* TO DO: make the text read only */
	for(va = KZERO; va < KZERO+64*MB; va += MB)
		ttb[MmuL1x(va|MINICACHED)] = va | 0xC10  | MmuIDC | MmuL1section;	/* cached but unbuffered (thus minicache) for frame buffer */
	ttb[MmuL1x(DCFADDR)] |= MmuIDC | MmuWB;	/* cached and buffered for cache writeback */
	ttb[MmuL1x(MCFADDR)] |= MmuIDC;	/* cached and unbuffered for minicache writeback */
	/* remap flash */
	for(i=0; i<32*MB; i+=MB)
		ttb[MmuL1x(FLASHMEM+i)] = (PHYSFLASH0+i) | 0xC10 | MmuL1section;	/* we'll make flash uncached for now */

	/*
	 * build page table for alternative vector page, mapping trap vectors in *page0
	 */
	ptable = xspanalloc(SectionPages*sizeof(*ptable), PtAlign, 0);
	ptable[MmuL2x(AIVECADDR)] = PADDR(page0) | MmuL2AP(MmuAPsrw) | MmuWB | MmuIDC | MmuL2small;
	ttb[MmuL1x(AIVECADDR)] = PADDR(ptable) | MmuL1page;
	mmuputttb(KTTB);
	mmuputdac(1);	/* client */
	mmuenable(CpCaltivec | CpCIcache | CpCsystem | (1<<6) | CpCd32 | CpCi32 | CpCwb | CpCDcache | CpCmmu);
}

/*
 * flush data in a given address range to memory
 * and invalidate the region in the instruction cache.
 */
int
segflush(void *a, ulong n)
{
	dcflush(a, n);
	icflushall();	/* can't be more precise */
	return 0;
}

/*
 * map an address to cached but unbuffered memory
 * forcing load allocations to the mini data cache.
 * the address a must be in a region that is cache line aligned
 * with a length that is a multiple of the cache line size
 */
void *
minicached(void *a)
{
	if(conf.useminicache == 0)
		return a;
	/* must flush and invalidate any data lingering in main cache */
	dcflushall();
	minidcflush();
	dcinval();
	return (void*)((ulong)a | MINICACHED);
}