release/src-rt-6.x.4708/linux/linux-2.6.36/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
  21 volatile 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
  30 static 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         for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE;
  41              mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
  42              memory_page += CHUNK_SIZE) {
  43                 dummy = *memory_page;
  44         }
  45         memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
  46
  47         add_memory_region(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE,
  48                           BOOT_MEM_RAM);
  49 }
  50
  51 /*
  52  * Use the REX prom calls to get hold of the memory bitmap, and thence
  53  * determine memory size.
  54  */
  55 static inline void rex_setup_memory_region(void)
  56 {
  57         int i, bitmap_size;
  58         unsigned long mem_start = 0, mem_size = 0;
  59         memmap *bm;
  60
  61         /* some free 64k */
  62         bm = (memmap *)CKSEG0ADDR(0x28000);
  63
  64         bitmap_size = rex_getbitmap(bm);
  65
  66         for (i = 0; i < bitmap_size; i++) {
  67                 if (bm->bitmap[i] == 0xff)
  68                         mem_size += (8 * bm->pagesize);
  69                 else if (!mem_size)
  70                         mem_start += (8 * bm->pagesize);
  71                 else {
  72                         add_memory_region(mem_start, mem_size, BOOT_MEM_RAM);
  73                         mem_start += mem_size + (8 * bm->pagesize);
  74                         mem_size = 0;
  75                 }
  76         }
  77         if (mem_size)
  78                 add_memory_region(mem_start, mem_size, BOOT_MEM_RAM);
  79 }
  80
  81 void __init prom_meminit(u32 magic)
  82 {
  83         if (!prom_is_rex(magic))
  84                 pmax_setup_memory_region();
  85         else
  86                 rex_setup_memory_region();
  87 }
  88
  89 void __init prom_free_prom_memory(void)
  90 {
  91         unsigned long end;
  92
  93         /*
  94          * Free everything below the kernel itself but leave
  95          * the first page reserved for the exception handlers.
  96          */
  97
  98 #if defined(CONFIG_DECLANCE) || defined(CONFIG_DECLANCE_MODULE)
  99         if (IOASIC)
 100                 end = __pa(&_text) - 0x00020000;
 101         else
 102 #endif
 103                 end = __pa(&_text);
 104
 105         free_init_pages("unused PROM memory", PAGE_SIZE, end);
 106 }