1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * memory.c: memory initialisation code. 4 * 5 * Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine 6 * Copyright (C) 2000, 2002 Maciej W. Rozycki 7 */ 8 #include <linux/init.h> 9 #include <linux/kernel.h> 10 #include <linux/mm.h> 11 #include <linux/memblock.h> 12 #include <linux/types.h> 13 14 #include <asm/addrspace.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 __init 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 memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE); 53 } 54 55 /* 56 * Use the REX prom calls to get hold of the memory bitmap, and thence 57 * determine memory size. 58 */ 59 static __init void rex_setup_memory_region(void) 60 { 61 int i, bitmap_size; 62 unsigned long mem_start = 0, mem_size = 0; 63 memmap *bm; 64 65 /* some free 64k */ 66 bm = (memmap *)CKSEG0ADDR(0x28000); 67 68 bitmap_size = rex_getbitmap(bm); 69 70 for (i = 0; i < bitmap_size; i++) { 71 /* FIXME: very simplistically only add full sets of pages */ 72 if (bm->bitmap[i] == 0xff) 73 mem_size += (8 * bm->pagesize); 74 else if (!mem_size) 75 mem_start += (8 * bm->pagesize); 76 else { 77 memblock_add(mem_start, mem_size); 78 mem_start += mem_size + (8 * bm->pagesize); 79 mem_size = 0; 80 } 81 } 82 if (mem_size) 83 memblock_add(mem_start, mem_size); 84 } 85 86 void __init prom_meminit(u32 magic) 87 { 88 if (!prom_is_rex(magic)) 89 pmax_setup_memory_region(); 90 else 91 rex_setup_memory_region(); 92 } 93 94 void __init prom_free_prom_memory(void) 95 { 96 unsigned long end; 97 98 /* 99 * Free everything below the kernel itself but leave 100 * the first page reserved for the exception handlers. 101 */ 102 103 #if IS_ENABLED(CONFIG_DECLANCE) 104 /* 105 * Leave 128 KB reserved for Lance memory for 106 * IOASIC DECstations. 107 * 108 * XXX: save this address for use in dec_lance.c? 109 */ 110 if (IOASIC) 111 end = __pa(&_text) - 0x00020000; 112 else 113 #endif 114 end = __pa(&_text); 115 116 free_init_pages("unused PROM memory", PAGE_SIZE, end); 117 } 118