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// SPDX-License-Identifier: GPL-2.0
/*
* memory.c: memory initialisation code.
*
* Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
* Copyright (C) 2000, 2002 Maciej W. Rozycki
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#include <linux/types.h>
#include <asm/addrspace.h>
#include <asm/dec/machtype.h>
#include <asm/dec/prom.h>
#include <asm/page.h>
#include <asm/sections.h>
volatile unsigned long mem_err; /* So we know an error occurred */
/*
* 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
static inline void pmax_setup_memory_region(void)
{
volatile unsigned char *memory_page, dummy;
char old_handler[0x80];
extern char genexcept_early;
/* Install exception handler */
memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80);
memcpy((void *)(CKSEG0 + 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 *)CKSEG1 + CHUNK_SIZE;
mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
memory_page += CHUNK_SIZE) {
dummy = *memory_page;
}
memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);
}
/*
* Use the REX prom calls to get hold of the memory bitmap, and thence
* determine memory size.
*/
static inline void rex_setup_memory_region(void)
{
int i, bitmap_size;
unsigned long mem_start = 0, mem_size = 0;
memmap *bm;
/* some free 64k */
bm = (memmap *)CKSEG0ADDR(0x28000);
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);
else if (!mem_size)
mem_start += (8 * bm->pagesize);
else {
memblock_add(mem_start, mem_size);
mem_start += mem_size + (8 * bm->pagesize);
mem_size = 0;
}
}
if (mem_size)
memblock_add(mem_start, mem_size);
}
void __init prom_meminit(u32 magic)
{
if (!prom_is_rex(magic))
pmax_setup_memory_region();
else
rex_setup_memory_region();
}
void __init prom_free_prom_memory(void)
{
unsigned long end;
/*
* Free everything below the kernel itself but leave
* the first page reserved for the exception handlers.
*/
#if IS_ENABLED(CONFIG_DECLANCE)
/*
* Leave 128 KB reserved for Lance memory for
* IOASIC DECstations.
*
* XXX: save this address for use in dec_lance.c?
*/
if (IOASIC)
end = __pa(&_text) - 0x00020000;
else
#endif
end = __pa(&_text);
free_init_pages("unused PROM memory", PAGE_SIZE, end);
}
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