153 lines
4.1 KiB
C
153 lines
4.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* This file contains the routines for initializing the MMU
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* on the 4xx series of chips.
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* -- paulus
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*
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* Derived from arch/ppc/mm/init.c:
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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*
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* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
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* and Cort Dougan (PReP) (cort@cs.nmt.edu)
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* Copyright (C) 1996 Paul Mackerras
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*
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* Derived from "arch/i386/mm/init.c"
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/stddef.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/highmem.h>
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#include <linux/memblock.h>
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#include <asm/prom.h>
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#include <asm/io.h>
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#include <asm/mmu_context.h>
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#include <asm/mmu.h>
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#include <linux/uaccess.h>
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#include <asm/smp.h>
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#include <asm/bootx.h>
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#include <asm/machdep.h>
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#include <asm/setup.h>
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#include <mm/mmu_decl.h>
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extern int __map_without_ltlbs;
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/*
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* MMU_init_hw does the chip-specific initialization of the MMU hardware.
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*/
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void __init MMU_init_hw(void)
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{
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/*
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* The Zone Protection Register (ZPR) defines how protection will
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* be applied to every page which is a member of a given zone. At
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* present, we utilize only two of the 4xx's zones.
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* The zone index bits (of ZSEL) in the PTE are used for software
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* indicators, except the LSB. For user access, zone 1 is used,
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* for kernel access, zone 0 is used. We set all but zone 1
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* to zero, allowing only kernel access as indicated in the PTE.
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* For zone 1, we set a 01 binary (a value of 10 will not work)
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* to allow user access as indicated in the PTE. This also allows
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* kernel access as indicated in the PTE.
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*/
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mtspr(SPRN_ZPR, 0x10000000);
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flush_instruction_cache();
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/*
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* Set up the real-mode cache parameters for the exception vector
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* handlers (which are run in real-mode).
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*/
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mtspr(SPRN_DCWR, 0x00000000); /* All caching is write-back */
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/*
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* Cache instruction and data space where the exception
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* vectors and the kernel live in real-mode.
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*/
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mtspr(SPRN_DCCR, 0xFFFF0000); /* 2GByte of data space at 0x0. */
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mtspr(SPRN_ICCR, 0xFFFF0000); /* 2GByte of instr. space at 0x0. */
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}
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#define LARGE_PAGE_SIZE_16M (1<<24)
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#define LARGE_PAGE_SIZE_4M (1<<22)
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unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
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{
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unsigned long v, s, mapped;
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phys_addr_t p;
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v = KERNELBASE;
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p = 0;
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s = total_lowmem;
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if (__map_without_ltlbs)
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return 0;
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while (s >= LARGE_PAGE_SIZE_16M) {
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pmd_t *pmdp;
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unsigned long val = p | _PMD_SIZE_16M | _PAGE_EXEC | _PAGE_RW;
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pmdp = pmd_off_k(v);
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*pmdp++ = __pmd(val);
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*pmdp++ = __pmd(val);
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*pmdp++ = __pmd(val);
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*pmdp++ = __pmd(val);
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v += LARGE_PAGE_SIZE_16M;
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p += LARGE_PAGE_SIZE_16M;
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s -= LARGE_PAGE_SIZE_16M;
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}
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while (s >= LARGE_PAGE_SIZE_4M) {
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pmd_t *pmdp;
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unsigned long val = p | _PMD_SIZE_4M | _PAGE_EXEC | _PAGE_RW;
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pmdp = pmd_off_k(v);
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*pmdp = __pmd(val);
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v += LARGE_PAGE_SIZE_4M;
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p += LARGE_PAGE_SIZE_4M;
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s -= LARGE_PAGE_SIZE_4M;
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}
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mapped = total_lowmem - s;
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/* If the size of RAM is not an exact power of two, we may not
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* have covered RAM in its entirety with 16 and 4 MiB
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* pages. Consequently, restrict the top end of RAM currently
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* allocable so that calls to the MEMBLOCK to allocate PTEs for "tail"
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* coverage with normal-sized pages (or other reasons) do not
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* attempt to allocate outside the allowed range.
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*/
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memblock_set_current_limit(mapped);
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return mapped;
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}
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void setup_initial_memory_limit(phys_addr_t first_memblock_base,
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phys_addr_t first_memblock_size)
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{
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/* We don't currently support the first MEMBLOCK not mapping 0
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* physical on those processors
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*/
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BUG_ON(first_memblock_base != 0);
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/* 40x can only access 16MB at the moment (see head_40x.S) */
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memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
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}
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