LXR linux-old/arch/cris/mm/ioremap.c

   1/*
   2 * arch/cris/mm/ioremap.c
   3 *
   4 * Re-map IO memory to kernel address space so that we can access it.
   5 * Needed for memory-mapped I/O devices mapped outside our normal DRAM
   6 * window (that is, all memory-mapped I/O devices).
   7 *
   8 * (C) Copyright 1995 1996 Linus Torvalds
   9 * CRIS-port by Axis Communications AB
  10 */
  11
  12#include <linux/vmalloc.h>
  13#include <asm/io.h>
  14#include <asm/pgalloc.h>
  15
  16extern inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  17        unsigned long phys_addr, unsigned long flags)
  18{
  19        unsigned long end;
  20
  21        address &= ~PMD_MASK;
  22        end = address + size;
  23        if (end > PMD_SIZE)
  24                end = PMD_SIZE;
  25        if (address >= end)
  26                BUG();
  27        do {
  28                if (!pte_none(*pte)) {
  29                        printk("remap_area_pte: page already exists\n");
  30                        BUG();
  31                }
  32                set_pte(pte, mk_pte_phys(phys_addr, __pgprot(_PAGE_PRESENT | __READABLE | 
  33                                                             __WRITEABLE | _PAGE_GLOBAL |
  34                                                             _PAGE_KERNEL | flags)));
  35                address += PAGE_SIZE;
  36                phys_addr += PAGE_SIZE;
  37                pte++;
  38        } while (address && (address < end));
  39}
  40
  41static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  42        unsigned long phys_addr, unsigned long flags)
  43{
  44        unsigned long end;
  45
  46        address &= ~PGDIR_MASK;
  47        end = address + size;
  48        if (end > PGDIR_SIZE)
  49                end = PGDIR_SIZE;
  50        phys_addr -= address;
  51        if (address >= end)
  52                BUG();
  53        do {
  54                pte_t * pte = pte_alloc(&init_mm, pmd, address);
  55                if (!pte)
  56                        return -ENOMEM;
  57                remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  58                address = (address + PMD_SIZE) & PMD_MASK;
  59                pmd++;
  60        } while (address && (address < end));
  61        return 0;
  62}
  63
  64static int remap_area_pages(unsigned long address, unsigned long phys_addr,
  65                                 unsigned long size, unsigned long flags)
  66{
  67        int error;
  68        pgd_t * dir;
  69        unsigned long end = address + size;
  70
  71        phys_addr -= address;
  72        dir = pgd_offset(&init_mm, address);
  73        flush_cache_all();
  74        if (address >= end)
  75                BUG();
  76        spin_lock(&init_mm.page_table_lock);
  77        do {
  78                pmd_t *pmd;
  79                pmd = pmd_alloc(&init_mm, dir, address);
  80                error = -ENOMEM;
  81                if (!pmd)
  82                        break;
  83                if (remap_area_pmd(pmd, address, end - address,
  84                                   phys_addr + address, flags))
  85                        break;
  86                error = 0;
  87                address = (address + PGDIR_SIZE) & PGDIR_MASK;
  88                dir++;
  89        } while (address && (address < end));
  90        spin_unlock(&init_mm.page_table_lock);
  91        flush_tlb_all();
  92        return error;
  93}
  94
  95/*
  96 * Generic mapping function (not visible outside):
  97 */
  98
  99/*
 100 * Remap an arbitrary physical address space into the kernel virtual
 101 * address space. Needed when the kernel wants to access high addresses
 102 * directly.
 103 *
 104 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 105 * have to convert them into an offset in a page-aligned mapping, but the
 106 * caller shouldn't need to know that small detail.
 107 */
 108void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 109{
 110        void * addr;
 111        struct vm_struct * area;
 112        unsigned long offset, last_addr;
 113
 114        /* Don't allow wraparound or zero size */
 115        last_addr = phys_addr + size - 1;
 116        if (!size || last_addr < phys_addr)
 117                return NULL;
 118
 119#if 0
 120        /* TODO: Here we can put checks for driver-writer abuse...  */
 121
 122        /*
 123         * Don't remap the low PCI/ISA area, it's always mapped..
 124         */
 125        if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 126                return phys_to_virt(phys_addr);
 127
 128        /*
 129         * Don't allow anybody to remap normal RAM that we're using..
 130         */
 131        if (phys_addr < virt_to_phys(high_memory)) {
 132                char *t_addr, *t_end;
 133                struct page *page;
 134
 135                t_addr = __va(phys_addr);
 136                t_end = t_addr + (size - 1);
 137           
 138                for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 139                        if(!PageReserved(page))
 140                                return NULL;
 141        }
 142#endif
 143
 144        /*
 145         * Mappings have to be page-aligned
 146         */
 147        offset = phys_addr & ~PAGE_MASK;
 148        phys_addr &= PAGE_MASK;
 149        size = PAGE_ALIGN(last_addr+1) - phys_addr;
 150
 151        /*
 152         * Ok, go for it..
 153         */
 154        area = get_vm_area(size, VM_IOREMAP);
 155        if (!area)
 156                return NULL;
 157        addr = area->addr;
 158        if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
 159                vfree(addr);
 160                return NULL;
 161        }
 162        return (void *) (offset + (char *)addr);
 163}
 164
 165void iounmap(void *addr)
 166{
 167        if (addr > high_memory)
 168                return vfree((void *) (PAGE_MASK & (unsigned long) addr));
 169}
 170