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         /* 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  */
  60 static 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
  87 void __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
  95 void __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 IS_ENABLED(CONFIG_DECLANCE)
 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 }