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pgtable.c

/*
 *  This file contains the routines setting up the linux page tables.
 *
 * Copyright (C) 2008 Michal Simek
 * Copyright (C) 2008 PetaLogix
 *
 *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
 *
 *  Derived from arch/ppc/mm/pgtable.c:
 *    -- 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
 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  This file is subject to the terms and conditions of the GNU General
 *  Public License.  See the file COPYING in the main directory of this
 *  archive for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include <linux/init.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <linux/io.h>
#include <asm/mmu.h>
#include <asm/sections.h>

#define flush_HPTE(X, va, pg) _tlbie(va)

unsigned long ioremap_base;
unsigned long ioremap_bot;

/* The maximum lowmem defaults to 768Mb, but this can be configured to
 * another value.
 */
#define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE

#ifndef CONFIG_SMP
struct pgtable_cache_struct quicklists;
#endif

static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
            unsigned long flags)
{
      unsigned long v, i;
      phys_addr_t p;
      int err;

      /*
       * Choose an address to map it to.
       * Once the vmalloc system is running, we use it.
       * Before then, we use space going down from ioremap_base
       * (ioremap_bot records where we're up to).
       */
      p = addr & PAGE_MASK;
      size = PAGE_ALIGN(addr + size) - p;

      /*
       * Don't allow anybody to remap normal RAM that we're using.
       * mem_init() sets high_memory so only do the check after that.
       *
       * However, allow remap of rootfs: TBD
       */
      if (mem_init_done &&
            p >= memory_start && p < virt_to_phys(high_memory) &&
            !(p >= virt_to_phys((unsigned long)&__bss_stop) &&
            p < virt_to_phys((unsigned long)__bss_stop))) {
            printk(KERN_WARNING "__ioremap(): phys addr "PTE_FMT
                  " is RAM lr %p\n", (unsigned long)p,
                  __builtin_return_address(0));
            return NULL;
      }

      if (size == 0)
            return NULL;

      /*
       * Is it already mapped? If the whole area is mapped then we're
       * done, otherwise remap it since we want to keep the virt addrs for
       * each request contiguous.
       *
       * We make the assumption here that if the bottom and top
       * of the range we want are mapped then it's mapped to the
       * same virt address (and this is contiguous).
       *  -- Cort
       */

      if (mem_init_done) {
            struct vm_struct *area;
            area = get_vm_area(size, VM_IOREMAP);
            if (area == NULL)
                  return NULL;
            v = VMALLOC_VMADDR(area->addr);
      } else {
            v = (ioremap_bot -= size);
      }

      if ((flags & _PAGE_PRESENT) == 0)
            flags |= _PAGE_KERNEL;
      if (flags & _PAGE_NO_CACHE)
            flags |= _PAGE_GUARDED;

      err = 0;
      for (i = 0; i < size && err == 0; i += PAGE_SIZE)
            err = map_page(v + i, p + i, flags);
      if (err) {
            if (mem_init_done)
                  vfree((void *)v);
            return NULL;
      }

      return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
}

void __iomem *ioremap(phys_addr_t addr, unsigned long size)
{
      return __ioremap(addr, size, _PAGE_NO_CACHE);
}
EXPORT_SYMBOL(ioremap);

void iounmap(void *addr)
{
      if (addr > high_memory && (unsigned long) addr < ioremap_bot)
            vfree((void *) (PAGE_MASK & (unsigned long) addr));
}
EXPORT_SYMBOL(iounmap);


int map_page(unsigned long va, phys_addr_t pa, int flags)
{
      pmd_t *pd;
      pte_t *pg;
      int err = -ENOMEM;
      /* spin_lock(&init_mm.page_table_lock); */
      /* Use upper 10 bits of VA to index the first level map */
      pd = pmd_offset(pgd_offset_k(va), va);
      /* Use middle 10 bits of VA to index the second-level map */
      pg = pte_alloc_kernel(pd, va); /* from powerpc - pgtable.c */
      /* pg = pte_alloc_kernel(&init_mm, pd, va); */

      if (pg != NULL) {
            err = 0;
            set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
                        __pgprot(flags)));
            if (mem_init_done)
                  flush_HPTE(0, va, pmd_val(*pd));
                  /* flush_HPTE(0, va, pg); */

      }
      /* spin_unlock(&init_mm.page_table_lock); */
      return err;
}

void __init adjust_total_lowmem(void)
{
/* TBD */
#if 0
      unsigned long max_low_mem = MAX_LOW_MEM;

      if (total_lowmem > max_low_mem) {
            total_lowmem = max_low_mem;
#ifndef CONFIG_HIGHMEM
            printk(KERN_INFO "Warning, memory limited to %ld Mb, use "
                        "CONFIG_HIGHMEM to reach %ld Mb\n",
                        max_low_mem >> 20, total_memory >> 20);
            total_memory = total_lowmem;
#endif /* CONFIG_HIGHMEM */
      }
#endif
}

static void show_tmem(unsigned long tmem)
{
      volatile unsigned long a;
      a = a + tmem;
}

/*
 * Map in all of physical memory starting at CONFIG_KERNEL_START.
 */
void __init mapin_ram(void)
{
      unsigned long v, p, s, f;

      v = CONFIG_KERNEL_START;
      p = memory_start;
      show_tmem(memory_size);
      for (s = 0; s < memory_size; s += PAGE_SIZE) {
            f = _PAGE_PRESENT | _PAGE_ACCESSED |
                        _PAGE_SHARED | _PAGE_HWEXEC;
            if ((char *) v < _stext || (char *) v >= _etext)
                  f |= _PAGE_WRENABLE;
            else
                  /* On the MicroBlaze, no user access
                     forces R/W kernel access */
                  f |= _PAGE_USER;
            map_page(v, p, f);
            v += PAGE_SIZE;
            p += PAGE_SIZE;
      }
}

/* is x a power of 2? */
#define is_power_of_2(x)      ((x) != 0 && (((x) & ((x) - 1)) == 0))

/*
 * Set up a mapping for a block of I/O.
 * virt, phys, size must all be page-aligned.
 * This should only be called before ioremap is called.
 */
void __init io_block_mapping(unsigned long virt, phys_addr_t phys,
                       unsigned int size, int flags)
{
      int i;

      if (virt > CONFIG_KERNEL_START && virt < ioremap_bot)
            ioremap_bot = ioremap_base = virt;

      /* Put it in the page tables. */
      for (i = 0; i < size; i += PAGE_SIZE)
            map_page(virt + i, phys + i, flags);
}

/* Scan the real Linux page tables and return a PTE pointer for
 * a virtual address in a context.
 * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 * the PTE pointer is unmodified if PTE is not found.
 */
static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
{
      pgd_t *pgd;
      pmd_t *pmd;
      pte_t *pte;
      int     retval = 0;

      pgd = pgd_offset(mm, addr & PAGE_MASK);
      if (pgd) {
            pmd = pmd_offset(pgd, addr & PAGE_MASK);
            if (pmd_present(*pmd)) {
                  pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
                  if (pte) {
                        retval = 1;
                        *ptep = pte;
                  }
            }
      }
      return retval;
}

/* Find physical address for this virtual address.  Normally used by
 * I/O functions, but anyone can call it.
 */
unsigned long iopa(unsigned long addr)
{
      unsigned long pa;

      pte_t *pte;
      struct mm_struct *mm;

      /* Allow mapping of user addresses (within the thread)
       * for DMA if necessary.
       */
      if (addr < TASK_SIZE)
            mm = current->mm;
      else
            mm = &init_mm;

      pa = 0;
      if (get_pteptr(mm, addr, &pte))
            pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);

      return pa;
}

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