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	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 */
55static 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
81void __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
89void __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}
107