arch/sh/mm/ioremap.c

   1 /* $Id: ioremap.c,v 1.9 2004/02/25 04:59:10 lethal Exp $
   2  *
   3  * arch/sh/mm/ioremap.c
   4  *
   5  * Re-map IO memory to kernel address space so that we can access it.
   6  * This is needed for high PCI addresses that aren't mapped in the
   7  * 640k-1MB IO memory area on PC's
   8  *
   9  * (C) Copyright 1995 1996 Linus Torvalds
  10  */
  11
  12 #include <linux/vmalloc.h>
  13 #include <linux/mm.h>
  14 #include <asm/io.h>
  15 #include <asm/page.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/tlbflush.h>
  19
  20 static inline void remap_area_pte(pte_t * pte, unsigned long address,
  21         unsigned long size, unsigned long phys_addr, unsigned long flags)
  22 {
  23         unsigned long end;
  24         unsigned long pfn;
  25         pgprot_t pgprot = __pgprot(_PAGE_PRESENT | _PAGE_RW |
  26                                    _PAGE_DIRTY | _PAGE_ACCESSED |
  27                                    _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | flags);
  28
  29         address &= ~PMD_MASK;
  30         end = address + size;
  31         if (end > PMD_SIZE)
  32                 end = PMD_SIZE;
  33         if (address >= end)
  34                 BUG();
  35         pfn = phys_addr >> PAGE_SHIFT;
  36         do {
  37                 if (!pte_none(*pte)) {
  38                         printk("remap_area_pte: page already exists\n");
  39                         BUG();
  40                 }
  41                 set_pte(pte, pfn_pte(pfn, pgprot));
  42                 address += PAGE_SIZE;
  43                 pfn++;
  44                 pte++;
  45         } while (address && (address < end));
  46 }
  47
  48 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address,
  49         unsigned long size, unsigned long phys_addr, unsigned long flags)
  50 {
  51         unsigned long end;
  52
  53         address &= ~PGDIR_MASK;
  54         end = address + size;
  55         if (end > PGDIR_SIZE)
  56                 end = PGDIR_SIZE;
  57         phys_addr -= address;
  58         if (address >= end)
  59                 BUG();
  60         do {
  61                 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
  62                 if (!pte)
  63                         return -ENOMEM;
  64                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  65                 address = (address + PMD_SIZE) & PMD_MASK;
  66                 pmd++;
  67         } while (address && (address < end));
  68         return 0;
  69 }
  70
  71 int remap_area_pages(unsigned long address, unsigned long phys_addr,
  72                      unsigned long size, unsigned long flags)
  73 {
  74         int error;
  75         pgd_t * dir;
  76         unsigned long end = address + size;
  77
  78         phys_addr -= address;
  79         dir = pgd_offset_k(address);
  80         flush_cache_all();
  81         if (address >= end)
  82                 BUG();
  83         spin_lock(&init_mm.page_table_lock);
  84         do {
  85                 pmd_t *pmd;
  86                 pmd = pmd_alloc(&init_mm, dir, address);
  87                 error = -ENOMEM;
  88                 if (!pmd)
  89                         break;
  90                 if (remap_area_pmd(pmd, address, end - address,
  91                                         phys_addr + address, flags))
  92                         break;
  93                 error = 0;
  94                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  95                 dir++;
  96         } while (address && (address < end));
  97         spin_unlock(&init_mm.page_table_lock);
  98         flush_tlb_all();
  99         return error;
 100 }
 101
 102 /*
 103  * Generic mapping function (not visible outside):
 104  */
 105
 106 /*
 107  * Remap an arbitrary physical address space into the kernel virtual
 108  * address space. Needed when the kernel wants to access high addresses
 109  * directly.
 110  *
 111  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 112  * have to convert them into an offset in a page-aligned mapping, but the
 113  * caller shouldn't need to know that small detail.
 114  */
 115 void * p3_ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 116 {
 117         void * addr;
 118         struct vm_struct * area;
 119         unsigned long offset, last_addr;
 120
 121         /* Don't allow wraparound or zero size */
 122         last_addr = phys_addr + size - 1;
 123         if (!size || last_addr < phys_addr)
 124                 return NULL;
 125
 126         /*
 127          * Don't remap the low PCI/ISA area, it's always mapped..
 128          */
 129         if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 130                 return phys_to_virt(phys_addr);
 131
 132         /*
 133          * Don't allow anybody to remap normal RAM that we're using..
 134          */
 135         if (phys_addr < virt_to_phys(high_memory))
 136                 return NULL;
 137
 138         /*
 139          * Mappings have to be page-aligned
 140          */
 141         offset = phys_addr & ~PAGE_MASK;
 142         phys_addr &= PAGE_MASK;
 143         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 144
 145         /*
 146          * Ok, go for it..
 147          */
 148         area = get_vm_area(size, VM_IOREMAP);
 149         if (!area)
 150                 return NULL;
 151         area->phys_addr = phys_addr;
 152         addr = area->addr;
 153         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 154                 vunmap(addr);
 155                 return NULL;
 156         }
 157         return (void *) (offset + (char *)addr);
 158 }
 159
 160 void p3_iounmap(void *addr)
 161 {
 162         if (addr > high_memory)
 163                 vfree((void *)(PAGE_MASK & (unsigned long)addr));
 164 }