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
  46 /* The maximum lowmem defaults to 768Mb, but this can be configured to
  47  * another value.
  48  */
  49 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  50
  51 #ifndef CONFIG_SMP
  52 struct pgtable_cache_struct quicklists;
  53 #endif
  54
  55 static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
  56                 unsigned long flags)
  57 {
  58         unsigned long v, i;
  59         phys_addr_t p;
  60         int err;
  61
  62         /*
  63          * Choose an address to map it to.
  64          * Once the vmalloc system is running, we use it.
  65          * Before then, we use space going down from ioremap_base
  66          * (ioremap_bot records where we're up to).
  67          */
  68         p = addr & PAGE_MASK;
  69         size = PAGE_ALIGN(addr + size) - p;
  70
  71         /*
  72          * Don't allow anybody to remap normal RAM that we're using.
  73          * mem_init() sets high_memory so only do the check after that.
  74          *
  75          * However, allow remap of rootfs: TBD
  76          */
  77         if (mem_init_done &&
  78                 p >= memory_start && p < virt_to_phys(high_memory) &&
  79                 !(p >= virt_to_phys((unsigned long)&__bss_stop) &&
  80                 p < virt_to_phys((unsigned long)__bss_stop))) {
  81                 printk(KERN_WARNING "__ioremap(): phys addr "PTE_FMT
  82                         " is RAM lr %p\n", (unsigned long)p,
  83                         __builtin_return_address(0));
  84                 return NULL;
  85         }
  86
  87         if (size == 0)
  88                 return NULL;
  89
  90         /*
  91          * Is it already mapped? If the whole area is mapped then we're
  92          * done, otherwise remap it since we want to keep the virt addrs for
  93          * each request contiguous.
  94          *
  95          * We make the assumption here that if the bottom and top
  96          * of the range we want are mapped then it's mapped to the
  97          * same virt address (and this is contiguous).
  98          *  -- Cort
  99          */
 100
 101         if (mem_init_done) {
 102                 struct vm_struct *area;
 103                 area = get_vm_area(size, VM_IOREMAP);
 104                 if (area == NULL)
 105                         return NULL;
 106                 v = VMALLOC_VMADDR(area->addr);
 107         } else {
 108                 v = (ioremap_bot -= size);
 109         }
 110
 111         if ((flags & _PAGE_PRESENT) == 0)
 112                 flags |= _PAGE_KERNEL;
 113         if (flags & _PAGE_NO_CACHE)
 114                 flags |= _PAGE_GUARDED;
 115
 116         err = 0;
 117         for (i = 0; i < size && err == 0; i += PAGE_SIZE)
 118                 err = map_page(v + i, p + i, flags);
 119         if (err) {
 120                 if (mem_init_done)
 121                         vfree((void *)v);
 122                 return NULL;
 123         }
 124
 125         return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
 126 }
 127
 128 void __iomem *ioremap(phys_addr_t addr, unsigned long size)
 129 {
 130         return __ioremap(addr, size, _PAGE_NO_CACHE);
 131 }
 132 EXPORT_SYMBOL(ioremap);
 133
 134 void iounmap(void *addr)
 135 {
 136         if (addr > high_memory && (unsigned long) addr < ioremap_bot)
 137                 vfree((void *) (PAGE_MASK & (unsigned long) addr));
 138 }
 139 EXPORT_SYMBOL(iounmap);
 140
 141
 142 int map_page(unsigned long va, phys_addr_t pa, int flags)
 143 {
 144         pmd_t *pd;
 145         pte_t *pg;
 146         int err = -ENOMEM;
 147         /* spin_lock(&init_mm.page_table_lock); */
 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 (mem_init_done)
 159                         flush_HPTE(0, va, pmd_val(*pd));
 160                         /* flush_HPTE(0, va, pg); */
 161
 162         }
 163         /* spin_unlock(&init_mm.page_table_lock); */
 164         return err;
 165 }
 166
 167 void __init adjust_total_lowmem(void)
 168 {
 169 /* TBD */
 170 #if 0
 171         unsigned long max_low_mem = MAX_LOW_MEM;
 172
 173         if (total_lowmem > max_low_mem) {
 174                 total_lowmem = max_low_mem;
 175 #ifndef CONFIG_HIGHMEM
 176                 printk(KERN_INFO "Warning, memory limited to %ld Mb, use "
 177                                 "CONFIG_HIGHMEM to reach %ld Mb\n",
 178                                 max_low_mem >> 20, total_memory >> 20);
 179                 total_memory = total_lowmem;
 180 #endif /* CONFIG_HIGHMEM */
 181         }
 182 #endif
 183 }
 184
 185 static void show_tmem(unsigned long tmem)
 186 {
 187         volatile unsigned long a;
 188         a = a + tmem;
 189 }
 190
 191 /*
 192  * Map in all of physical memory starting at CONFIG_KERNEL_START.
 193  */
 194 void __init mapin_ram(void)
 195 {
 196         unsigned long v, p, s, f;
 197
 198         v = CONFIG_KERNEL_START;
 199         p = memory_start;
 200         show_tmem(memory_size);
 201         for (s = 0; s < memory_size; s += PAGE_SIZE) {
 202                 f = _PAGE_PRESENT | _PAGE_ACCESSED |
 203                                 _PAGE_SHARED | _PAGE_HWEXEC;
 204                 if ((char *) v < _stext || (char *) v >= _etext)
 205                         f |= _PAGE_WRENABLE;
 206                 else
 207                         /* On the MicroBlaze, no user access
 208                            forces R/W kernel access */
 209                         f |= _PAGE_USER;
 210                 map_page(v, p, f);
 211                 v += PAGE_SIZE;
 212                 p += PAGE_SIZE;
 213         }
 214 }
 215
 216 /* is x a power of 2? */
 217 #define is_power_of_2(x)        ((x) != 0 && (((x) & ((x) - 1)) == 0))
 218
 219 /*
 220  * Set up a mapping for a block of I/O.
 221  * virt, phys, size must all be page-aligned.
 222  * This should only be called before ioremap is called.
 223  */
 224 void __init io_block_mapping(unsigned long virt, phys_addr_t phys,
 225                              unsigned int size, int flags)
 226 {
 227         int i;
 228
 229         if (virt > CONFIG_KERNEL_START && virt < ioremap_bot)
 230                 ioremap_bot = ioremap_base = virt;
 231
 232         /* Put it in the page tables. */
 233         for (i = 0; i < size; i += PAGE_SIZE)
 234                 map_page(virt + i, phys + i, flags);
 235 }
 236
 237 /* Scan the real Linux page tables and return a PTE pointer for
 238  * a virtual address in a context.
 239  * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 240  * the PTE pointer is unmodified if PTE is not found.
 241  */
 242 static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
 243 {
 244         pgd_t   *pgd;
 245         pmd_t   *pmd;
 246         pte_t   *pte;
 247         int     retval = 0;
 248
 249         pgd = pgd_offset(mm, addr & PAGE_MASK);
 250         if (pgd) {
 251                 pmd = pmd_offset(pgd, addr & PAGE_MASK);
 252                 if (pmd_present(*pmd)) {
 253                         pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
 254                         if (pte) {
 255                                 retval = 1;
 256                                 *ptep = pte;
 257                         }
 258                 }
 259         }
 260         return retval;
 261 }
 262
 263 /* Find physical address for this virtual address.  Normally used by
 264  * I/O functions, but anyone can call it.
 265  */
 266 unsigned long iopa(unsigned long addr)
 267 {
 268         unsigned long pa;
 269
 270         pte_t *pte;
 271         struct mm_struct *mm;
 272
 273         /* Allow mapping of user addresses (within the thread)
 274          * for DMA if necessary.
 275          */
 276         if (addr < TASK_SIZE)
 277                 mm = current->mm;
 278         else
 279                 mm = &init_mm;
 280
 281         pa = 0;
 282         if (get_pteptr(mm, addr, &pte))
 283                 pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
 284
 285         return pa;
 286 }