40x_mmu.c
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/*
* This file contains the routines for initializing the MMU
* on the 4xx series of chips.
* -- paulus
*
* Derived from arch/ppc/mm/init.c:
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
* and Cort Dougan (PReP) (cort@cs.nmt.edu)
* Copyright (C) 1996 Paul Mackerras
*
* Derived from "arch/i386/mm/init.c"
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/highmem.h>
#include <linux/memblock.h>
#include <asm/pgalloc.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/uaccess.h>
#include <asm/smp.h>
#include <asm/bootx.h>
#include <asm/machdep.h>
#include <asm/setup.h>
#include "mmu_decl.h"
extern int __map_without_ltlbs;
/*
* MMU_init_hw does the chip-specific initialization of the MMU hardware.
*/
void __init MMU_init_hw(void)
{
/*
* The Zone Protection Register (ZPR) defines how protection will
* be applied to every page which is a member of a given zone. At
* present, we utilize only two of the 4xx's zones.
* The zone index bits (of ZSEL) in the PTE are used for software
* indicators, except the LSB. For user access, zone 1 is used,
* for kernel access, zone 0 is used. We set all but zone 1
* to zero, allowing only kernel access as indicated in the PTE.
* For zone 1, we set a 01 binary (a value of 10 will not work)
* to allow user access as indicated in the PTE. This also allows
* kernel access as indicated in the PTE.
*/
mtspr(SPRN_ZPR, 0x10000000);
flush_instruction_cache();
/*
* Set up the real-mode cache parameters for the exception vector
* handlers (which are run in real-mode).
*/
mtspr(SPRN_DCWR, 0x00000000); /* All caching is write-back */
/*
* Cache instruction and data space where the exception
* vectors and the kernel live in real-mode.
*/
mtspr(SPRN_DCCR, 0xFFFF0000); /* 2GByte of data space at 0x0. */
mtspr(SPRN_ICCR, 0xFFFF0000); /* 2GByte of instr. space at 0x0. */
}
#define LARGE_PAGE_SIZE_16M (1<<24)
#define LARGE_PAGE_SIZE_4M (1<<22)
unsigned long __init mmu_mapin_ram(unsigned long top)
{
unsigned long v, s, mapped;
phys_addr_t p;
v = KERNELBASE;
p = 0;
s = total_lowmem;
if (__map_without_ltlbs)
return 0;
while (s >= LARGE_PAGE_SIZE_16M) {
pmd_t *pmdp;
unsigned long val = p | _PMD_SIZE_16M | _PAGE_EXEC | _PAGE_HWWRITE;
pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
pmd_val(*pmdp++) = val;
pmd_val(*pmdp++) = val;
pmd_val(*pmdp++) = val;
pmd_val(*pmdp++) = val;
v += LARGE_PAGE_SIZE_16M;
p += LARGE_PAGE_SIZE_16M;
s -= LARGE_PAGE_SIZE_16M;
}
while (s >= LARGE_PAGE_SIZE_4M) {
pmd_t *pmdp;
unsigned long val = p | _PMD_SIZE_4M | _PAGE_EXEC | _PAGE_HWWRITE;
pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
pmd_val(*pmdp) = val;
v += LARGE_PAGE_SIZE_4M;
p += LARGE_PAGE_SIZE_4M;
s -= LARGE_PAGE_SIZE_4M;
}
mapped = total_lowmem - s;
/* If the size of RAM is not an exact power of two, we may not
* have covered RAM in its entirety with 16 and 4 MiB
* pages. Consequently, restrict the top end of RAM currently
* allocable so that calls to the MEMBLOCK to allocate PTEs for "tail"
* coverage with normal-sized pages (or other reasons) do not
* attempt to allocate outside the allowed range.
*/
memblock_set_current_limit(mapped);
return mapped;
}
void setup_initial_memory_limit(phys_addr_t first_memblock_base,
phys_addr_t first_memblock_size)
{
/* We don't currently support the first MEMBLOCK not mapping 0
* physical on those processors
*/
BUG_ON(first_memblock_base != 0);
/* 40x can only access 16MB at the moment (see head_40x.S) */
memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
}