118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* memory.c: memory initialisation code.
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*
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* Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
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* Copyright (C) 2000, 2002 Maciej W. Rozycki
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/memblock.h>
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#include <linux/types.h>
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#include <asm/addrspace.h>
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#include <asm/dec/machtype.h>
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#include <asm/dec/prom.h>
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#include <asm/page.h>
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#include <asm/sections.h>
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volatile unsigned long mem_err; /* So we know an error occurred */
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/*
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* Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
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* off the end of real memory. Only suitable for the 2100/3100's (PMAX).
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*/
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#define CHUNK_SIZE 0x400000
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static __init void pmax_setup_memory_region(void)
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{
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volatile unsigned char *memory_page, dummy;
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char old_handler[0x80];
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extern char genexcept_early;
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/* Install exception handler */
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memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80);
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memcpy((void *)(CKSEG0 + 0x80), &genexcept_early, 0x80);
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/* read unmapped and uncached (KSEG1)
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* DECstations have at least 4MB RAM
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* Assume less than 480MB of RAM, as this is max for 5000/2xx
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* FIXME this should be replaced by the first free page!
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*/
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for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE;
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mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
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memory_page += CHUNK_SIZE) {
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dummy = *memory_page;
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}
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memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
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memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);
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}
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/*
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* Use the REX prom calls to get hold of the memory bitmap, and thence
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* determine memory size.
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*/
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static __init void rex_setup_memory_region(void)
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{
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int i, bitmap_size;
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unsigned long mem_start = 0, mem_size = 0;
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memmap *bm;
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/* some free 64k */
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bm = (memmap *)CKSEG0ADDR(0x28000);
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bitmap_size = rex_getbitmap(bm);
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for (i = 0; i < bitmap_size; i++) {
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/* FIXME: very simplistically only add full sets of pages */
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if (bm->bitmap[i] == 0xff)
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mem_size += (8 * bm->pagesize);
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else if (!mem_size)
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mem_start += (8 * bm->pagesize);
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else {
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memblock_add(mem_start, mem_size);
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mem_start += mem_size + (8 * bm->pagesize);
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mem_size = 0;
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}
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}
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if (mem_size)
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memblock_add(mem_start, mem_size);
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}
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void __init prom_meminit(u32 magic)
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{
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if (!prom_is_rex(magic))
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pmax_setup_memory_region();
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else
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rex_setup_memory_region();
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}
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void __init prom_free_prom_memory(void)
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{
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unsigned long end;
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/*
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* Free everything below the kernel itself but leave
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* the first page reserved for the exception handlers.
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*/
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#if IS_ENABLED(CONFIG_DECLANCE)
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/*
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* Leave 128 KB reserved for Lance memory for
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* IOASIC DECstations.
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*
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* XXX: save this address for use in dec_lance.c?
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*/
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if (IOASIC)
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end = __pa(&_text) - 0x00020000;
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else
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#endif
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end = __pa(&_text);
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free_init_pages("unused PROM memory", PAGE_SIZE, end);
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}
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