LXR linux/arch/mips/dec/prom/memory.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * memory.c: memory initialisation code.
   4 *
   5 * Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
   6 * Copyright (C) 2000, 2002  Maciej W. Rozycki
   7 */
   8#include <linux/init.h>
   9#include <linux/kernel.h>
  10#include <linux/mm.h>
  11#include <linux/memblock.h>
  12#include <linux/types.h>
  13
  14#include <asm/addrspace.h>
  15#include <asm/dec/machtype.h>
  16#include <asm/dec/prom.h>
  17#include <asm/page.h>
  18#include <asm/sections.h>
  19
  20
  21volatile unsigned long mem_err;         /* So we know an error occurred */
  22
  23/*
  24 * Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
  25 * off the end of real memory.  Only suitable for the 2100/3100's (PMAX).
  26 */
  27
  28#define CHUNK_SIZE 0x400000
  29
  30static __init void pmax_setup_memory_region(void)
  31{
  32        volatile unsigned char *memory_page, dummy;
  33        char old_handler[0x80];
  34        extern char genexcept_early;
  35
  36        /* Install exception handler */
  37        memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80);
  38        memcpy((void *)(CKSEG0 + 0x80), &genexcept_early, 0x80);
  39
  40        /* read unmapped and uncached (KSEG1)
  41         * DECstations have at least 4MB RAM
  42         * Assume less than 480MB of RAM, as this is max for 5000/2xx
  43         * FIXME this should be replaced by the first free page!
  44         */
  45        for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE;
  46             mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
  47             memory_page += CHUNK_SIZE) {
  48                dummy = *memory_page;
  49        }
  50        memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
  51
  52        memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);
  53}
  54
  55/*
  56 * Use the REX prom calls to get hold of the memory bitmap, and thence
  57 * determine memory size.
  58 */
  59static __init void rex_setup_memory_region(void)
  60{
  61        int i, bitmap_size;
  62        unsigned long mem_start = 0, mem_size = 0;
  63        memmap *bm;
  64
  65        /* some free 64k */
  66        bm = (memmap *)CKSEG0ADDR(0x28000);
  67
  68        bitmap_size = rex_getbitmap(bm);
  69
  70        for (i = 0; i < bitmap_size; i++) {
  71                /* FIXME: very simplistically only add full sets of pages */
  72                if (bm->bitmap[i] == 0xff)
  73                        mem_size += (8 * bm->pagesize);
  74                else if (!mem_size)
  75                        mem_start += (8 * bm->pagesize);
  76                else {
  77                        memblock_add(mem_start, mem_size);
  78                        mem_start += mem_size + (8 * bm->pagesize);
  79                        mem_size = 0;
  80                }
  81        }
  82        if (mem_size)
  83                memblock_add(mem_start, mem_size);
  84}
  85
  86void __init prom_meminit(u32 magic)
  87{
  88        if (!prom_is_rex(magic))
  89                pmax_setup_memory_region();
  90        else
  91                rex_setup_memory_region();
  92}
  93
  94void __init prom_free_prom_memory(void)
  95{
  96        unsigned long end;
  97
  98        /*
  99         * Free everything below the kernel itself but leave
 100         * the first page reserved for the exception handlers.
 101         */
 102
 103#if IS_ENABLED(CONFIG_DECLANCE)
 104        /*
 105         * Leave 128 KB reserved for Lance memory for
 106         * IOASIC DECstations.
 107         *
 108         * XXX: save this address for use in dec_lance.c?
 109         */
 110        if (IOASIC)
 111                end = __pa(&_text) - 0x00020000;
 112        else
 113#endif
 114                end = __pa(&_text);
 115
 116        free_init_pages("unused PROM memory", PAGE_SIZE, end);
 117}
 118