arch/microblaze/mm/pgtable.c

   1 /*
   2  *  This file contains the routines setting up the linux page tables.
   3  *
   4  * Copyright (C) 2008 Michal Simek
   5  * Copyright (C) 2008 PetaLogix
   6  *
   7  *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
   8  *
   9  *  Derived from arch/ppc/mm/pgtable.c:
  10  *    -- paulus
  11  *
  12  *  Derived from arch/ppc/mm/init.c:
  13  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  14  *
  15  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  16  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  17  *    Copyright (C) 1996 Paul Mackerras
  18  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
  19  *
  20  *  Derived from "arch/i386/mm/init.c"
  21  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  22  *
  23  *  This file is subject to the terms and conditions of the GNU General
  24  *  Public License.  See the file COPYING in the main directory of this
  25  *  archive for more details.
  26  *
  27  */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/types.h>
  32 #include <linux/vmalloc.h>
  33 #include <linux/init.h>
  34
  35 #include <asm/pgtable.h>
  36 #include <asm/pgalloc.h>
  37 #include <linux/io.h>
  38 #include <asm/mmu.h>
  39 #include <asm/sections.h>
  40
  41 #define flush_HPTE(X, va, pg)   _tlbie(va)
  42
  43 unsigned long ioremap_base;
  44 unsigned long ioremap_bot;
  45 EXPORT_SYMBOL(ioremap_bot);
  46
  47 /* The maximum lowmem defaults to 768Mb, but this can be configured to
  48  * another value.
  49  */
  50 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  51
  52 #ifndef CONFIG_SMP
  53 struct pgtable_cache_struct quicklists;
  54 #endif
  55
  56 static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
  57                 unsigned long flags)
  58 {
  59         unsigned long v, i;
  60         phys_addr_t p;
  61         int err;
  62
  63         /*
  64          * Choose an address to map it to.
  65          * Once the vmalloc system is running, we use it.
  66          * Before then, we use space going down from ioremap_base
  67          * (ioremap_bot records where we're up to).
  68          */
  69         p = addr & PAGE_MASK;
  70         size = PAGE_ALIGN(addr + size) - p;
  71
  72         /*
  73          * Don't allow anybody to remap normal RAM that we're using.
  74          * mem_init() sets high_memory so only do the check after that.
  75          *
  76          * However, allow remap of rootfs: TBD
  77          */
  78         if (mem_init_done &&
  79                 p >= memory_start && p < virt_to_phys(high_memory) &&
  80                 !(p >= virt_to_phys((unsigned long)&__bss_stop) &&
  81                 p < virt_to_phys((unsigned long)__bss_stop))) {
  82                 printk(KERN_WARNING "__ioremap(): phys addr "PTE_FMT
  83                         " is RAM lr %p\n", (unsigned long)p,
  84                         __builtin_return_address(0));
  85                 return NULL;
  86         }
  87
  88         if (size == 0)
  89                 return NULL;
  90
  91         /*
  92          * Is it already mapped? If the whole area is mapped then we're
  93          * done, otherwise remap it since we want to keep the virt addrs for
  94          * each request contiguous.
  95          *
  96          * We make the assumption here that if the bottom and top
  97          * of the range we want are mapped then it's mapped to the
  98          * same virt address (and this is contiguous).
  99          *  -- Cort
 100          */
 101
 102         if (mem_init_done) {
 103                 struct vm_struct *area;
 104                 area = get_vm_area(size, VM_IOREMAP);
 105                 if (area == NULL)
 106                         return NULL;
 107                 v = (unsigned long) area->addr;
 108         } else {
 109                 v = (ioremap_bot -= size);
 110         }
 111
 112         if ((flags & _PAGE_PRESENT) == 0)
 113                 flags |= _PAGE_KERNEL;
 114         if (flags & _PAGE_NO_CACHE)
 115                 flags |= _PAGE_GUARDED;
 116
 117         err = 0;
 118         for (i = 0; i < size && err == 0; i += PAGE_SIZE)
 119                 err = map_page(v + i, p + i, flags);
 120         if (err) {
 121                 if (mem_init_done)
 122                         vfree((void *)v);
 123                 return NULL;
 124         }
 125
 126         return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
 127 }
 128
 129 void __iomem *ioremap(phys_addr_t addr, unsigned long size)
 130 {
 131         return __ioremap(addr, size, _PAGE_NO_CACHE);
 132 }
 133 EXPORT_SYMBOL(ioremap);
 134
 135 void iounmap(void *addr)
 136 {
 137         if (addr > high_memory && (unsigned long) addr < ioremap_bot)
 138                 vfree((void *) (PAGE_MASK & (unsigned long) addr));
 139 }
 140 EXPORT_SYMBOL(iounmap);
 141
 142
 143 int map_page(unsigned long va, phys_addr_t pa, int flags)
 144 {
 145         pmd_t *pd;
 146         pte_t *pg;
 147         int err = -ENOMEM;
 148         /* Use upper 10 bits of VA to index the first level map */
 149         pd = pmd_offset(pgd_offset_k(va), va);
 150         /* Use middle 10 bits of VA to index the second-level map */
 151         pg = pte_alloc_kernel(pd, va); /* from powerpc - pgtable.c */
 152         /* pg = pte_alloc_kernel(&init_mm, pd, va); */
 153
 154         if (pg != NULL) {
 155                 err = 0;
 156                 set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
 157                                 __pgprot(flags)));
 158                 if (unlikely(mem_init_done))
 159                         flush_HPTE(0, va, pmd_val(*pd));
 160                         /* flush_HPTE(0, va, pg); */
 161         }
 162         return err;
 163 }
 164
 165 /*
 166  * Map in all of physical memory starting at CONFIG_KERNEL_START.
 167  */
 168 void __init mapin_ram(void)
 169 {
 170         unsigned long v, p, s, f;
 171
 172         v = CONFIG_KERNEL_START;
 173         p = memory_start;
 174         for (s = 0; s < memory_size; s += PAGE_SIZE) {
 175                 f = _PAGE_PRESENT | _PAGE_ACCESSED |
 176                                 _PAGE_SHARED | _PAGE_HWEXEC;
 177                 if ((char *) v < _stext || (char *) v >= _etext)
 178                         f |= _PAGE_WRENABLE;
 179                 else
 180                         /* On the MicroBlaze, no user access
 181                            forces R/W kernel access */
 182                         f |= _PAGE_USER;
 183                 map_page(v, p, f);
 184                 v += PAGE_SIZE;
 185                 p += PAGE_SIZE;
 186         }
 187 }
 188
 189 /* is x a power of 2? */
 190 #define is_power_of_2(x)        ((x) != 0 && (((x) & ((x) - 1)) == 0))
 191
 192 /* Scan the real Linux page tables and return a PTE pointer for
 193  * a virtual address in a context.
 194  * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 195  * the PTE pointer is unmodified if PTE is not found.
 196  */
 197 static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
 198 {
 199         pgd_t   *pgd;
 200         pmd_t   *pmd;
 201         pte_t   *pte;
 202         int     retval = 0;
 203
 204         pgd = pgd_offset(mm, addr & PAGE_MASK);
 205         if (pgd) {
 206                 pmd = pmd_offset(pgd, addr & PAGE_MASK);
 207                 if (pmd_present(*pmd)) {
 208                         pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
 209                         if (pte) {
 210                                 retval = 1;
 211                                 *ptep = pte;
 212                         }
 213                 }
 214         }
 215         return retval;
 216 }
 217
 218 /* Find physical address for this virtual address.  Normally used by
 219  * I/O functions, but anyone can call it.
 220  */
 221 unsigned long iopa(unsigned long addr)
 222 {
 223         unsigned long pa;
 224
 225         pte_t *pte;
 226         struct mm_struct *mm;
 227
 228         /* Allow mapping of user addresses (within the thread)
 229          * for DMA if necessary.
 230          */
 231         if (addr < TASK_SIZE)
 232                 mm = current->mm;
 233         else
 234                 mm = &init_mm;
 235
 236         pa = 0;
 237         if (get_pteptr(mm, addr, &pte))
 238                 pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
 239
 240         return pa;
 241 }
 242
 243 __init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
 244                 unsigned long address)
 245 {
 246         pte_t *pte;
 247         if (mem_init_done) {
 248                 pte = (pte_t *)__get_free_page(GFP_KERNEL |
 249                                         __GFP_REPEAT | __GFP_ZERO);
 250         } else {
 251                 pte = (pte_t *)early_get_page();
 252                 if (pte)
 253                         clear_page(pte);
 254         }
 255         return pte;
 256 }