/*
 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
 * Copyright (C) 2009 Wind River Systems Inc
 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
 * Copyright (C) 2004 Microtronix Datacom Ltd.
 *
 * 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/export.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/io.h>

#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

static inline void remap_area_pte(pte_t *pte, unsigned long address,
                                unsigned long size, unsigned long phys_addr,
                                unsigned long flags)
{
        unsigned long end;
        unsigned long pfn;
        pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_READ
                                | _PAGE_WRITE | flags);

        address &= ~PMD_MASK;
        end = address + size;
        if (end > PMD_SIZE)
                end = PMD_SIZE;
        if (address >= end)
                BUG();
        pfn = PFN_DOWN(phys_addr);
        do {
                if (!pte_none(*pte)) {
                        pr_err("remap_area_pte: page already exists\n");
                        BUG();
                }
                set_pte(pte, pfn_pte(pfn, pgprot));
                address += PAGE_SIZE;
                pfn++;
                pte++;
        } while (address && (address < end));
}

static inline int remap_area_pmd(pmd_t *pmd, unsigned long address,
                                unsigned long size, unsigned long phys_addr,
                                unsigned long flags)
{
        unsigned long end;

        address &= ~PGDIR_MASK;
        end = address + size;
        if (end > PGDIR_SIZE)
                end = PGDIR_SIZE;
        phys_addr -= address;
        if (address >= end)
                BUG();
        do {
                pte_t *pte = pte_alloc_kernel(pmd, address);

                if (!pte)
                        return -ENOMEM;
                remap_area_pte(pte, address, end - address, address + phys_addr,
                        flags);
                address = (address + PMD_SIZE) & PMD_MASK;
                pmd++;
        } while (address && (address < end));
        return 0;
}

static int remap_area_pages(unsigned long address, unsigned long phys_addr,
                                unsigned long size, unsigned long flags)
{
        int error;
        pgd_t *dir;
        unsigned long end = address + size;

        phys_addr -= address;
        dir = pgd_offset(&init_mm, address);
        flush_cache_all();
        if (address >= end)
                BUG();
        do {
                p4d_t *p4d;
                pud_t *pud;
                pmd_t *pmd;

                error = -ENOMEM;
                p4d = p4d_alloc(&init_mm, dir, address);
                if (!p4d)
                        break;
                pud = pud_alloc(&init_mm, p4d, address);
                if (!pud)
                        break;
                pmd = pmd_alloc(&init_mm, pud, address);
                if (!pmd)
                        break;
                if (remap_area_pmd(pmd, address, end - address,
                        phys_addr + address, flags))
                        break;
                error = 0;
                address = (address + PGDIR_SIZE) & PGDIR_MASK;
                dir++;
        } while (address && (address < end));
        flush_tlb_all();
        return error;
}

#define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)

/*
 * Map some physical address range into the kernel address space.
 */
void __iomem *ioremap(unsigned long phys_addr, unsigned long size)
{
        struct vm_struct *area;
        unsigned long offset;
        unsigned long last_addr;
        void *addr;

        /* Don't allow wraparound or zero size */
        last_addr = phys_addr + size - 1;

        if (!size || last_addr < phys_addr)
                return NULL;

        /* Don't allow anybody to remap normal RAM that we're using */
        if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(high_memory)) {
                char *t_addr, *t_end;
                struct page *page;

                t_addr = __va(phys_addr);
                t_end = t_addr + (size - 1);
                for (page = virt_to_page(t_addr);
                        page <= virt_to_page(t_end); page++)
                        if (!PageReserved(page))
                                return NULL;
        }

        /*
         * Map uncached objects in the low part of address space to
         * CONFIG_NIOS2_IO_REGION_BASE
         */
        if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
            IS_MAPPABLE_UNCACHEABLE(last_addr))
                return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);

        /* Mappings have to be page-aligned */
        offset = phys_addr & ~PAGE_MASK;
        phys_addr &= PAGE_MASK;
        size = PAGE_ALIGN(last_addr + 1) - phys_addr;

        /* Ok, go for it */
        area = get_vm_area(size, VM_IOREMAP);
        if (!area)
                return NULL;
        addr = area->addr;
        if (remap_area_pages((unsigned long) addr, phys_addr, size, 0)) {
                vunmap(addr);
                return NULL;
        }
        return (void __iomem *) (offset + (char *)addr);
}
EXPORT_SYMBOL(ioremap);

/*
 * iounmap unmaps nearly everything, so be careful
 * it doesn't free currently pointer/page tables anymore but it
 * wasn't used anyway and might be added later.
 */
void iounmap(void __iomem *addr)
{
        struct vm_struct *p;

        if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
                return;

        p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
        if (!p)
                pr_err("iounmap: bad address %p\n", addr);
        kfree(p);
}
EXPORT_SYMBOL(iounmap);