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;		/* 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 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}
119