xref: /linux/arch/powerpc/mm/init_32.c (revision e0bf6c5ca2d3281f231c5f0c9bf145e9513644de)
1 /*
2  *  PowerPC version
3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
4  *
5  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
6  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
7  *    Copyright (C) 1996 Paul Mackerras
8  *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
9  *
10  *  Derived from "arch/i386/mm/init.c"
11  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
12  *
13  *  This program is free software; you can redistribute it and/or
14  *  modify it under the terms of the GNU General Public License
15  *  as published by the Free Software Foundation; either version
16  *  2 of the License, or (at your option) any later version.
17  *
18  */
19 
20 #include <linux/module.h>
21 #include <linux/sched.h>
22 #include <linux/kernel.h>
23 #include <linux/errno.h>
24 #include <linux/string.h>
25 #include <linux/types.h>
26 #include <linux/mm.h>
27 #include <linux/stddef.h>
28 #include <linux/init.h>
29 #include <linux/highmem.h>
30 #include <linux/initrd.h>
31 #include <linux/pagemap.h>
32 #include <linux/memblock.h>
33 #include <linux/gfp.h>
34 #include <linux/slab.h>
35 #include <linux/hugetlb.h>
36 
37 #include <asm/pgalloc.h>
38 #include <asm/prom.h>
39 #include <asm/io.h>
40 #include <asm/pgtable.h>
41 #include <asm/mmu.h>
42 #include <asm/smp.h>
43 #include <asm/machdep.h>
44 #include <asm/btext.h>
45 #include <asm/tlb.h>
46 #include <asm/sections.h>
47 #include <asm/hugetlb.h>
48 
49 #include "mmu_decl.h"
50 
51 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
52 /* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
53 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
54 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
55 #endif
56 #endif
57 #define MAX_LOW_MEM	CONFIG_LOWMEM_SIZE
58 
59 phys_addr_t total_memory;
60 phys_addr_t total_lowmem;
61 
62 phys_addr_t memstart_addr = (phys_addr_t)~0ull;
63 EXPORT_SYMBOL(memstart_addr);
64 phys_addr_t kernstart_addr;
65 EXPORT_SYMBOL(kernstart_addr);
66 
67 #ifdef CONFIG_RELOCATABLE_PPC32
68 /* Used in __va()/__pa() */
69 long long virt_phys_offset;
70 EXPORT_SYMBOL(virt_phys_offset);
71 #endif
72 
73 phys_addr_t lowmem_end_addr;
74 
75 int boot_mapsize;
76 #ifdef CONFIG_PPC_PMAC
77 unsigned long agp_special_page;
78 EXPORT_SYMBOL(agp_special_page);
79 #endif
80 
81 void MMU_init(void);
82 
83 /* XXX should be in current.h  -- paulus */
84 extern struct task_struct *current_set[NR_CPUS];
85 
86 /*
87  * this tells the system to map all of ram with the segregs
88  * (i.e. page tables) instead of the bats.
89  * -- Cort
90  */
91 int __map_without_bats;
92 int __map_without_ltlbs;
93 
94 /*
95  * This tells the system to allow ioremapping memory marked as reserved.
96  */
97 int __allow_ioremap_reserved;
98 
99 /* max amount of low RAM to map in */
100 unsigned long __max_low_memory = MAX_LOW_MEM;
101 
102 /*
103  * Check for command-line options that affect what MMU_init will do.
104  */
105 void __init MMU_setup(void)
106 {
107 	/* Check for nobats option (used in mapin_ram). */
108 	if (strstr(boot_command_line, "nobats")) {
109 		__map_without_bats = 1;
110 	}
111 
112 	if (strstr(boot_command_line, "noltlbs")) {
113 		__map_without_ltlbs = 1;
114 	}
115 #ifdef CONFIG_DEBUG_PAGEALLOC
116 	__map_without_bats = 1;
117 	__map_without_ltlbs = 1;
118 #endif
119 }
120 
121 /*
122  * MMU_init sets up the basic memory mappings for the kernel,
123  * including both RAM and possibly some I/O regions,
124  * and sets up the page tables and the MMU hardware ready to go.
125  */
126 void __init MMU_init(void)
127 {
128 	if (ppc_md.progress)
129 		ppc_md.progress("MMU:enter", 0x111);
130 
131 	/* parse args from command line */
132 	MMU_setup();
133 
134 	/*
135 	 * Reserve gigantic pages for hugetlb.  This MUST occur before
136 	 * lowmem_end_addr is initialized below.
137 	 */
138 	reserve_hugetlb_gpages();
139 
140 	if (memblock.memory.cnt > 1) {
141 #ifndef CONFIG_WII
142 		memblock_enforce_memory_limit(memblock.memory.regions[0].size);
143 		printk(KERN_WARNING "Only using first contiguous memory region");
144 #else
145 		wii_memory_fixups();
146 #endif
147 	}
148 
149 	total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
150 	lowmem_end_addr = memstart_addr + total_lowmem;
151 
152 #ifdef CONFIG_FSL_BOOKE
153 	/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
154 	 * entries, so we need to adjust lowmem to match the amount we can map
155 	 * in the fixed entries */
156 	adjust_total_lowmem();
157 #endif /* CONFIG_FSL_BOOKE */
158 
159 	if (total_lowmem > __max_low_memory) {
160 		total_lowmem = __max_low_memory;
161 		lowmem_end_addr = memstart_addr + total_lowmem;
162 #ifndef CONFIG_HIGHMEM
163 		total_memory = total_lowmem;
164 		memblock_enforce_memory_limit(total_lowmem);
165 #endif /* CONFIG_HIGHMEM */
166 	}
167 
168 	/* Initialize the MMU hardware */
169 	if (ppc_md.progress)
170 		ppc_md.progress("MMU:hw init", 0x300);
171 	MMU_init_hw();
172 
173 	/* Map in all of RAM starting at KERNELBASE */
174 	if (ppc_md.progress)
175 		ppc_md.progress("MMU:mapin", 0x301);
176 	mapin_ram();
177 
178 	/* Initialize early top-down ioremap allocator */
179 	ioremap_bot = IOREMAP_TOP;
180 
181 	/* Map in I/O resources */
182 	if (ppc_md.progress)
183 		ppc_md.progress("MMU:setio", 0x302);
184 
185 	if (ppc_md.progress)
186 		ppc_md.progress("MMU:exit", 0x211);
187 
188 	/* From now on, btext is no longer BAT mapped if it was at all */
189 #ifdef CONFIG_BOOTX_TEXT
190 	btext_unmap();
191 #endif
192 
193 	/* Shortly after that, the entire linear mapping will be available */
194 	memblock_set_current_limit(lowmem_end_addr);
195 }
196 
197 #ifdef CONFIG_8xx /* No 8xx specific .c file to put that in ... */
198 void setup_initial_memory_limit(phys_addr_t first_memblock_base,
199 				phys_addr_t first_memblock_size)
200 {
201 	/* We don't currently support the first MEMBLOCK not mapping 0
202 	 * physical on those processors
203 	 */
204 	BUG_ON(first_memblock_base != 0);
205 
206 #ifdef CONFIG_PIN_TLB
207 	/* 8xx can only access 24MB at the moment */
208 	memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01800000));
209 #else
210 	/* 8xx can only access 8MB at the moment */
211 	memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
212 #endif
213 }
214 #endif /* CONFIG_8xx */
215