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/bootinfo.h> 16 #include <asm/dec/machtype.h> 17 #include <asm/dec/prom.h> 18 #include <asm/page.h> 19 #include <asm/sections.h> 20 21 22 volatile unsigned long mem_err; /* So we know an error occurred */ 23 24 /* 25 * Probe memory in 4MB chunks, waiting for an error to tell us we've fallen 26 * off the end of real memory. Only suitable for the 2100/3100's (PMAX). 27 */ 28 29 #define CHUNK_SIZE 0x400000 30 31 static inline void pmax_setup_memory_region(void) 32 { 33 volatile unsigned char *memory_page, dummy; 34 char old_handler[0x80]; 35 extern char genexcept_early; 36 37 /* Install exception handler */ 38 memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80); 39 memcpy((void *)(CKSEG0 + 0x80), &genexcept_early, 0x80); 40 41 /* read unmapped and uncached (KSEG1) 42 * DECstations have at least 4MB RAM 43 * Assume less than 480MB of RAM, as this is max for 5000/2xx 44 * FIXME this should be replaced by the first free page! 45 */ 46 for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE; 47 mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000; 48 memory_page += CHUNK_SIZE) { 49 dummy = *memory_page; 50 } 51 memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80); 52 53 add_memory_region(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE, 54 BOOT_MEM_RAM); 55 } 56 57 /* 58 * Use the REX prom calls to get hold of the memory bitmap, and thence 59 * determine memory size. 60 */ 61 static inline void rex_setup_memory_region(void) 62 { 63 int i, bitmap_size; 64 unsigned long mem_start = 0, mem_size = 0; 65 memmap *bm; 66 67 /* some free 64k */ 68 bm = (memmap *)CKSEG0ADDR(0x28000); 69 70 bitmap_size = rex_getbitmap(bm); 71 72 for (i = 0; i < bitmap_size; i++) { 73 /* FIXME: very simplistically only add full sets of pages */ 74 if (bm->bitmap[i] == 0xff) 75 mem_size += (8 * bm->pagesize); 76 else if (!mem_size) 77 mem_start += (8 * bm->pagesize); 78 else { 79 add_memory_region(mem_start, mem_size, BOOT_MEM_RAM); 80 mem_start += mem_size + (8 * bm->pagesize); 81 mem_size = 0; 82 } 83 } 84 if (mem_size) 85 add_memory_region(mem_start, mem_size, BOOT_MEM_RAM); 86 } 87 88 void __init prom_meminit(u32 magic) 89 { 90 if (!prom_is_rex(magic)) 91 pmax_setup_memory_region(); 92 else 93 rex_setup_memory_region(); 94 } 95 96 void __init prom_free_prom_memory(void) 97 { 98 unsigned long end; 99 100 /* 101 * Free everything below the kernel itself but leave 102 * the first page reserved for the exception handlers. 103 */ 104 105 #if IS_ENABLED(CONFIG_DECLANCE) 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(&_text) - 0x00020000; 114 else 115 #endif 116 end = __pa(&_text); 117 118 free_init_pages("unused PROM memory", PAGE_SIZE, end); 119 } 120