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  *
   6  * $Id: $
   7  */
   8 #include <asm/addrspace.h>
   9 #include <linux/init.h>
  10 #include <linux/config.h>
  11 #include <linux/string.h>
  12 #include "prom.h"
  13
  14 typedef struct {
  15         int pagesize;
  16         unsigned char bitmap[0];
  17 } memmap;
  18
  19 extern int (*rex_getbitmap)(memmap *);
  20
  21 #undef PROM_DEBUG
  22
  23 #ifdef PROM_DEBUG
  24 extern int (*prom_printf)(char *, ...);
  25 #endif
  26
  27 extern unsigned long mips_memory_upper;
  28
  29 volatile unsigned long mem_err = 0;     /* So we know an error occured */
  30
  31 /*
  32  * Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
  33  * off the end of real memory.  Only suitable for the 2100/3100's (PMAX).
  34  */
  35
  36 #define CHUNK_SIZE 0x400000
  37
  38 __initfunc(unsigned long pmax_get_memory_size(void))
  39 {
  40         volatile unsigned char *memory_page, dummy;
  41         char    old_handler[0x80];
  42         extern char genexcept_early;
  43
  44         /* Install exception handler */
  45         memcpy(&old_handler, (void *)(KSEG0 + 0x80), 0x80);
  46         memcpy((void *)(KSEG0 + 0x80), &genexcept_early, 0x80);
  47
  48         /* read unmapped and uncached (KSEG1)
  49          * DECstations have at least 4MB RAM
  50          * Assume less than 480MB of RAM, as this is max for 5000/2xx
  51          * FIXME this should be replaced by the first free page!
  52          */
  53         for (memory_page = (unsigned char *) KSEG1 + CHUNK_SIZE;
  54              (mem_err== 0) && (memory_page < ((unsigned char *) KSEG1+0x1E000000));
  55              memory_page += CHUNK_SIZE) {
  56                 dummy = *memory_page;
  57         }
  58         memcpy((void *)(KSEG0 + 0x80), &old_handler, 0x80);
  59         return (unsigned long)memory_page - KSEG1 - CHUNK_SIZE;
  60 }
  61
  62 /*
  63  * Use the REX prom calls to get hold of the memory bitmap, and thence
  64  * determine memory size.
  65  */
  66 __initfunc(unsigned long rex_get_memory_size(void))
  67 {
  68         int i, bitmap_size;
  69         unsigned long mem_size = 0;
  70         memmap *bm;
  71
  72         /* some free 64k */
  73         bm = (memmap *) 0x80028000;
  74
  75         bitmap_size = rex_getbitmap(bm);
  76
  77         for (i = 0; i < bitmap_size; i++) {
  78                 /* FIXME: very simplistically only add full sets of pages */
  79                 if (bm->bitmap[i] == 0xff)
  80                         mem_size += (8 * bm->pagesize);
  81         }
  82         return (mem_size);
  83 }
  84
  85 __initfunc(void prom_meminit(unsigned int magic))
  86 {
  87         if (magic != REX_PROM_MAGIC)
  88                 mips_memory_upper = KSEG0 + pmax_get_memory_size();
  89         else
  90                 mips_memory_upper = KSEG0 + rex_get_memory_size();
  91
  92 #ifdef PROM_DEBUG
  93         prom_printf("mips_memory_upper: 0x%08x\n", mips_memory_upper);
  94 #endif
  95 }
  96
  97 /* Called from mem_init() to fixup the mem_map page settings. */
  98 __initfunc(void prom_fixup_mem_map(unsigned long start, unsigned long end))
  99 {
 100 }
 101
 102 void prom_free_prom_memory (void)
 103 {
 104 }