LXR linux/arch/nios2/mm/ioremap.c

   1/*
   2 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
   3 * Copyright (C) 2009 Wind River Systems Inc
   4 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
   5 * Copyright (C) 2004 Microtronix Datacom Ltd.
   6 *
   7 * This file is subject to the terms and conditions of the GNU General Public
   8 * License. See the file "COPYING" in the main directory of this archive
   9 * for more details.
  10 */
  11
  12#include <linux/export.h>
  13#include <linux/sched.h>
  14#include <linux/mm.h>
  15#include <linux/slab.h>
  16#include <linux/vmalloc.h>
  17#include <linux/io.h>
  18
  19#include <asm/cacheflush.h>
  20#include <asm/tlbflush.h>
  21
  22static inline void remap_area_pte(pte_t *pte, unsigned long address,
  23                                unsigned long size, unsigned long phys_addr,
  24                                unsigned long flags)
  25{
  26        unsigned long end;
  27        unsigned long pfn;
  28        pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_READ
  29                                | _PAGE_WRITE | flags);
  30
  31        address &= ~PMD_MASK;
  32        end = address + size;
  33        if (end > PMD_SIZE)
  34                end = PMD_SIZE;
  35        if (address >= end)
  36                BUG();
  37        pfn = PFN_DOWN(phys_addr);
  38        do {
  39                if (!pte_none(*pte)) {
  40                        pr_err("remap_area_pte: page already exists\n");
  41                        BUG();
  42                }
  43                set_pte(pte, pfn_pte(pfn, pgprot));
  44                address += PAGE_SIZE;
  45                pfn++;
  46                pte++;
  47        } while (address && (address < end));
  48}
  49
  50static inline int remap_area_pmd(pmd_t *pmd, unsigned long address,
  51                                unsigned long size, unsigned long phys_addr,
  52                                unsigned long flags)
  53{
  54        unsigned long end;
  55
  56        address &= ~PGDIR_MASK;
  57        end = address + size;
  58        if (end > PGDIR_SIZE)
  59                end = PGDIR_SIZE;
  60        phys_addr -= address;
  61        if (address >= end)
  62                BUG();
  63        do {
  64                pte_t *pte = pte_alloc_kernel(pmd, address);
  65
  66                if (!pte)
  67                        return -ENOMEM;
  68                remap_area_pte(pte, address, end - address, address + phys_addr,
  69                        flags);
  70                address = (address + PMD_SIZE) & PMD_MASK;
  71                pmd++;
  72        } while (address && (address < end));
  73        return 0;
  74}
  75
  76static int remap_area_pages(unsigned long address, unsigned long phys_addr,
  77                                unsigned long size, unsigned long flags)
  78{
  79        int error;
  80        pgd_t *dir;
  81        unsigned long end = address + size;
  82
  83        phys_addr -= address;
  84        dir = pgd_offset(&init_mm, address);
  85        flush_cache_all();
  86        if (address >= end)
  87                BUG();
  88        do {
  89                p4d_t *p4d;
  90                pud_t *pud;
  91                pmd_t *pmd;
  92
  93                error = -ENOMEM;
  94                p4d = p4d_alloc(&init_mm, dir, address);
  95                if (!p4d)
  96                        break;
  97                pud = pud_alloc(&init_mm, p4d, address);
  98                if (!pud)
  99                        break;
 100                pmd = pmd_alloc(&init_mm, pud, address);
 101                if (!pmd)
 102                        break;
 103                if (remap_area_pmd(pmd, address, end - address,
 104                        phys_addr + address, flags))
 105                        break;
 106                error = 0;
 107                address = (address + PGDIR_SIZE) & PGDIR_MASK;
 108                dir++;
 109        } while (address && (address < end));
 110        flush_tlb_all();
 111        return error;
 112}
 113
 114#define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)
 115
 116/*
 117 * Map some physical address range into the kernel address space.
 118 */
 119void __iomem *ioremap(unsigned long phys_addr, unsigned long size)
 120{
 121        struct vm_struct *area;
 122        unsigned long offset;
 123        unsigned long last_addr;
 124        void *addr;
 125
 126        /* Don't allow wraparound or zero size */
 127        last_addr = phys_addr + size - 1;
 128
 129        if (!size || last_addr < phys_addr)
 130                return NULL;
 131
 132        /* Don't allow anybody to remap normal RAM that we're using */
 133        if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(high_memory)) {
 134                char *t_addr, *t_end;
 135                struct page *page;
 136
 137                t_addr = __va(phys_addr);
 138                t_end = t_addr + (size - 1);
 139                for (page = virt_to_page(t_addr);
 140                        page <= virt_to_page(t_end); page++)
 141                        if (!PageReserved(page))
 142                                return NULL;
 143        }
 144
 145        /*
 146         * Map uncached objects in the low part of address space to
 147         * CONFIG_NIOS2_IO_REGION_BASE
 148         */
 149        if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
 150            IS_MAPPABLE_UNCACHEABLE(last_addr))
 151                return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
 152
 153        /* Mappings have to be page-aligned */
 154        offset = phys_addr & ~PAGE_MASK;
 155        phys_addr &= PAGE_MASK;
 156        size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 157
 158        /* Ok, go for it */
 159        area = get_vm_area(size, VM_IOREMAP);
 160        if (!area)
 161                return NULL;
 162        addr = area->addr;
 163        if (remap_area_pages((unsigned long) addr, phys_addr, size, 0)) {
 164                vunmap(addr);
 165                return NULL;
 166        }
 167        return (void __iomem *) (offset + (char *)addr);
 168}
 169EXPORT_SYMBOL(ioremap);
 170
 171/*
 172 * iounmap unmaps nearly everything, so be careful
 173 * it doesn't free currently pointer/page tables anymore but it
 174 * wasn't used anyway and might be added later.
 175 */
 176void iounmap(void __iomem *addr)
 177{
 178        struct vm_struct *p;
 179
 180        if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
 181                return;
 182
 183        p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 184        if (!p)
 185                pr_err("iounmap: bad address %p\n", addr);
 186        kfree(p);
 187}
 188EXPORT_SYMBOL(iounmap);
 189