arch/sh/mm/ioremap.c

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