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/config.h>
8 #include <linux/init.h>
9 #include <linux/kernel.h>
10 #include <linux/mm.h>
11 #include <linux/bootmem.h>
12 #include <linux/types.h>
13
14 #include <asm/addrspace.h>
15 #include <asm/bootinfo.h>
16 #include <asm/dec/machtype.h>
17 #include <asm/dec/prom.h>
18 #include <asm/page.h>
19
20
21 volatile 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
pmax_setup_memory_region(void)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 *)(KSEG0 + 0x80), 0x80);
38 memcpy((void *)(KSEG0 + 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 *) KSEG1 + CHUNK_SIZE;
46 (mem_err== 0) && (memory_page < ((unsigned char *) KSEG1+0x1E000000));
47 memory_page += CHUNK_SIZE) {
48 dummy = *memory_page;
49 }
50 memcpy((void *)(KSEG0 + 0x80), &old_handler, 0x80);
51
52 add_memory_region(0, (unsigned long)memory_page - KSEG1 - 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 */
rex_setup_memory_region(void)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 *)KSEG0ADDR(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
prom_meminit(u32 magic)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
prom_free_prom_memory(void)95 void __init prom_free_prom_memory (void)
96 {
97 unsigned long addr, end;
98 extern char _ftext;
99
100 /*
101 * Free everything below the kernel itself but leave
102 * the first page reserved for the exception handlers.
103 */
104
105 #if defined(CONFIG_DECLANCE) || defined(CONFIG_DECLANCE_MODULE)
106 /*
107 * Leave 128 KB reserved for Lance memory for
108 * IOASIC DECstations.
109 *
110 * XXX: save this address for use in dec_lance.c?
111 */
112 if (IOASIC)
113 end = __pa(&_ftext) - 0x00020000;
114 else
115 #endif
116 end = __pa(&_ftext);
117
118 addr = PAGE_SIZE;
119 while (addr < end) {
120 ClearPageReserved(virt_to_page(__va(addr)));
121 set_page_count(virt_to_page(__va(addr)), 1);
122 free_page((unsigned long)__va(addr));
123 addr += PAGE_SIZE;
124 }
125
126 printk("Freeing unused PROM memory: %ldk freed\n",
127 (end - PAGE_SIZE) >> 10);
128 }
129