/*
 *  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;
EXPORT_SYMBOL(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 = (unsigned long) 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;
        /* 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 (unlikely(mem_init_done))
                        flush_HPTE(0, va, pmd_val(*pd));
                        /* flush_HPTE(0, va, pg); */
        }
        return err;
}

/*
 * 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;
        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))

/* 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;
}

__init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
                unsigned long address)
{
        pte_t *pte;
        if (mem_init_done) {
                pte = (pte_t *)__get_free_page(GFP_KERNEL |
                                        __GFP_REPEAT | __GFP_ZERO);
        } else {
                pte = (pte_t *)early_get_page();
                if (pte)
                        clear_page(pte);
        }
        return pte;
}