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 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 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 */ 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 *)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 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 95 void __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