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

   1/*
   2 * memory.c: memory initialisation code.
   3 *
   4 * Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
   5 * Copyright (C) 2000, 2002  Maciej W. Rozycki
   6 */
   7#include <linux/init.h>
   8#include <linux/kernel.h>
   9#include <linux/mm.h>
  10#include <linux/bootmem.h>
  11#include <linux/types.h>
  12
  13#include <asm/addrspace.h>
  14#include <asm/bootinfo.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 = 0;     /* 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 inline 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        add_memory_region(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE,
  53                          BOOT_MEM_RAM);
  54}
  55
  56/*
  57 * Use the REX prom calls to get hold of the memory bitmap, and thence
  58 * determine memory size.
  59 */
  60static inline void rex_setup_memory_region(void)
  61{
  62        int i, bitmap_size;
  63        unsigned long mem_start = 0, mem_size = 0;
  64        memmap *bm;
  65
  66        /* some free 64k */
  67        bm = (memmap *)CKSEG0ADDR(0x28000);
  68
  69        bitmap_size = rex_getbitmap(bm);
  70
  71        for (i = 0; i < bitmap_size; i++) {
  72                /* FIXME: very simplistically only add full sets of pages */
  73                if (bm->bitmap[i] == 0xff)
  74                        mem_size += (8 * bm->pagesize);
  75                else if (!mem_size)
  76                        mem_start += (8 * bm->pagesize);
  77                else {
  78                        add_memory_region(mem_start, mem_size, BOOT_MEM_RAM);
  79                        mem_start += mem_size + (8 * bm->pagesize);
  80                        mem_size = 0;
  81                }
  82        }
  83        if (mem_size)
  84                add_memory_region(mem_start, mem_size, BOOT_MEM_RAM);
  85}
  86
  87void __init prom_meminit(u32 magic)
  88{
  89        if (!prom_is_rex(magic))
  90                pmax_setup_memory_region();
  91        else
  92                rex_setup_memory_region();
  93}
  94
  95void __init prom_free_prom_memory(void)
  96{
  97        unsigned long end;
  98
  99        /*
 100         * Free everything below the kernel itself but leave
 101         * the first page reserved for the exception handlers.
 102         */
 103
 104#if defined(CONFIG_DECLANCE) || defined(CONFIG_DECLANCE_MODULE)
 105        /*
 106         * Leave 128 KB reserved for Lance memory for
 107         * IOASIC DECstations.
 108         *
 109         * XXX: save this address for use in dec_lance.c?
 110         */
 111        if (IOASIC)
 112                end = __pa(&_text) - 0x00020000;
 113        else
 114#endif
 115                end = __pa(&_text);
 116
 117        free_init_pages("unused PROM memory", PAGE_SIZE, end);
 118}
 119