1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * memory.c: memory initialisation code.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
6*4882a593Smuzhiyun * Copyright (C) 2000, 2002 Maciej W. Rozycki
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun #include <linux/init.h>
9*4882a593Smuzhiyun #include <linux/kernel.h>
10*4882a593Smuzhiyun #include <linux/mm.h>
11*4882a593Smuzhiyun #include <linux/memblock.h>
12*4882a593Smuzhiyun #include <linux/types.h>
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun #include <asm/addrspace.h>
15*4882a593Smuzhiyun #include <asm/dec/machtype.h>
16*4882a593Smuzhiyun #include <asm/dec/prom.h>
17*4882a593Smuzhiyun #include <asm/page.h>
18*4882a593Smuzhiyun #include <asm/sections.h>
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun volatile unsigned long mem_err; /* So we know an error occurred */
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun /*
24*4882a593Smuzhiyun * Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
25*4882a593Smuzhiyun * off the end of real memory. Only suitable for the 2100/3100's (PMAX).
26*4882a593Smuzhiyun */
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun #define CHUNK_SIZE 0x400000
29*4882a593Smuzhiyun
pmax_setup_memory_region(void)30*4882a593Smuzhiyun static __init void pmax_setup_memory_region(void)
31*4882a593Smuzhiyun {
32*4882a593Smuzhiyun volatile unsigned char *memory_page, dummy;
33*4882a593Smuzhiyun char old_handler[0x80];
34*4882a593Smuzhiyun extern char genexcept_early;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun /* Install exception handler */
37*4882a593Smuzhiyun memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80);
38*4882a593Smuzhiyun memcpy((void *)(CKSEG0 + 0x80), &genexcept_early, 0x80);
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun /* read unmapped and uncached (KSEG1)
41*4882a593Smuzhiyun * DECstations have at least 4MB RAM
42*4882a593Smuzhiyun * Assume less than 480MB of RAM, as this is max for 5000/2xx
43*4882a593Smuzhiyun * FIXME this should be replaced by the first free page!
44*4882a593Smuzhiyun */
45*4882a593Smuzhiyun for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE;
46*4882a593Smuzhiyun mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
47*4882a593Smuzhiyun memory_page += CHUNK_SIZE) {
48*4882a593Smuzhiyun dummy = *memory_page;
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun /*
56*4882a593Smuzhiyun * Use the REX prom calls to get hold of the memory bitmap, and thence
57*4882a593Smuzhiyun * determine memory size.
58*4882a593Smuzhiyun */
rex_setup_memory_region(void)59*4882a593Smuzhiyun static __init void rex_setup_memory_region(void)
60*4882a593Smuzhiyun {
61*4882a593Smuzhiyun int i, bitmap_size;
62*4882a593Smuzhiyun unsigned long mem_start = 0, mem_size = 0;
63*4882a593Smuzhiyun memmap *bm;
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun /* some free 64k */
66*4882a593Smuzhiyun bm = (memmap *)CKSEG0ADDR(0x28000);
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun bitmap_size = rex_getbitmap(bm);
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun for (i = 0; i < bitmap_size; i++) {
71*4882a593Smuzhiyun /* FIXME: very simplistically only add full sets of pages */
72*4882a593Smuzhiyun if (bm->bitmap[i] == 0xff)
73*4882a593Smuzhiyun mem_size += (8 * bm->pagesize);
74*4882a593Smuzhiyun else if (!mem_size)
75*4882a593Smuzhiyun mem_start += (8 * bm->pagesize);
76*4882a593Smuzhiyun else {
77*4882a593Smuzhiyun memblock_add(mem_start, mem_size);
78*4882a593Smuzhiyun mem_start += mem_size + (8 * bm->pagesize);
79*4882a593Smuzhiyun mem_size = 0;
80*4882a593Smuzhiyun }
81*4882a593Smuzhiyun }
82*4882a593Smuzhiyun if (mem_size)
83*4882a593Smuzhiyun memblock_add(mem_start, mem_size);
84*4882a593Smuzhiyun }
85*4882a593Smuzhiyun
prom_meminit(u32 magic)86*4882a593Smuzhiyun void __init prom_meminit(u32 magic)
87*4882a593Smuzhiyun {
88*4882a593Smuzhiyun if (!prom_is_rex(magic))
89*4882a593Smuzhiyun pmax_setup_memory_region();
90*4882a593Smuzhiyun else
91*4882a593Smuzhiyun rex_setup_memory_region();
92*4882a593Smuzhiyun }
93*4882a593Smuzhiyun
prom_free_prom_memory(void)94*4882a593Smuzhiyun void __init prom_free_prom_memory(void)
95*4882a593Smuzhiyun {
96*4882a593Smuzhiyun unsigned long end;
97*4882a593Smuzhiyun
98*4882a593Smuzhiyun /*
99*4882a593Smuzhiyun * Free everything below the kernel itself but leave
100*4882a593Smuzhiyun * the first page reserved for the exception handlers.
101*4882a593Smuzhiyun */
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun #if IS_ENABLED(CONFIG_DECLANCE)
104*4882a593Smuzhiyun /*
105*4882a593Smuzhiyun * Leave 128 KB reserved for Lance memory for
106*4882a593Smuzhiyun * IOASIC DECstations.
107*4882a593Smuzhiyun *
108*4882a593Smuzhiyun * XXX: save this address for use in dec_lance.c?
109*4882a593Smuzhiyun */
110*4882a593Smuzhiyun if (IOASIC)
111*4882a593Smuzhiyun end = __pa(&_text) - 0x00020000;
112*4882a593Smuzhiyun else
113*4882a593Smuzhiyun #endif
114*4882a593Smuzhiyun end = __pa(&_text);
115*4882a593Smuzhiyun
116*4882a593Smuzhiyun free_init_pages("unused PROM memory", PAGE_SIZE, end);
117*4882a593Smuzhiyun }
118