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/*
* memory.c: memory initialisation code.
*
* Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
*
* $Id: $
*/
#include <asm/addrspace.h>
#include <linux/init.h>
#include <linux/config.h>
#include <linux/string.h>
#include "prom.h"
typedef struct {
int pagesize;
unsigned char bitmap[0];
} memmap;
extern int (*rex_getbitmap)(memmap *);
#undef PROM_DEBUG
#ifdef PROM_DEBUG
extern int (*prom_printf)(char *, ...);
#endif
extern unsigned long mips_memory_upper;
volatile unsigned long mem_err = 0; /* So we know an error occured */
/*
* Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
* off the end of real memory. Only suitable for the 2100/3100's (PMAX).
*/
#define CHUNK_SIZE 0x400000
__initfunc(unsigned long pmax_get_memory_size(void))
{
volatile unsigned char *memory_page, dummy;
char old_handler[0x80];
extern char genexcept_early;
/* Install exception handler */
memcpy(&old_handler, (void *)(KSEG0 + 0x80), 0x80);
memcpy((void *)(KSEG0 + 0x80), &genexcept_early, 0x80);
/* read unmapped and uncached (KSEG1)
* DECstations have at least 4MB RAM
* Assume less than 480MB of RAM, as this is max for 5000/2xx
* FIXME this should be replaced by the first free page!
*/
for (memory_page = (unsigned char *) KSEG1 + CHUNK_SIZE;
(mem_err== 0) && (memory_page < ((unsigned char *) KSEG1+0x1E000000));
memory_page += CHUNK_SIZE) {
dummy = *memory_page;
}
memcpy((void *)(KSEG0 + 0x80), &old_handler, 0x80);
return (unsigned long)memory_page - KSEG1 - CHUNK_SIZE;
}
/*
* Use the REX prom calls to get hold of the memory bitmap, and thence
* determine memory size.
*/
__initfunc(unsigned long rex_get_memory_size(void))
{
int i, bitmap_size;
unsigned long mem_size = 0;
memmap *bm;
/* some free 64k */
bm = (memmap *) 0x80028000;
bitmap_size = rex_getbitmap(bm);
for (i = 0; i < bitmap_size; i++) {
/* FIXME: very simplistically only add full sets of pages */
if (bm->bitmap[i] == 0xff)
mem_size += (8 * bm->pagesize);
}
return (mem_size);
}
__initfunc(void prom_meminit(unsigned int magic))
{
if (magic != REX_PROM_MAGIC)
mips_memory_upper = KSEG0 + pmax_get_memory_size();
else
mips_memory_upper = KSEG0 + rex_get_memory_size();
#ifdef PROM_DEBUG
prom_printf("mips_memory_upper: 0x%08x\n", mips_memory_upper);
#endif
}
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