arch/mips/mm/ioremap.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * (C) Copyright 1995 1996 Linus Torvalds
   7  * (C) Copyright 2001, 2002 Ralf Baechle
   8  */
   9 #include <linux/export.h>
  10 #include <asm/addrspace.h>
  11 #include <asm/byteorder.h>
  12 #include <linux/ioport.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/mm_types.h>
  17 #include <linux/io.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/tlbflush.h>
  20 #include <ioremap.h>
  21
  22 #define IS_LOW512(addr) (!((phys_addr_t)(addr) & (phys_addr_t) ~0x1fffffffULL))
  23 #define IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)
  24
  25 static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,
  26                                void *arg)
  27 {
  28         unsigned long i;
  29
  30         for (i = 0; i < nr_pages; i++) {
  31                 if (pfn_valid(start_pfn + i) &&
  32                     !PageReserved(pfn_to_page(start_pfn + i)))
  33                         return 1;
  34         }
  35
  36         return 0;
  37 }
  38
  39 /*
  40  * ioremap_prot     -   map bus memory into CPU space
  41  * @phys_addr:    bus address of the memory
  42  * @size:      size of the resource to map
  43  *
  44  * ioremap_prot gives the caller control over cache coherency attributes (CCA)
  45  */
  46 void __iomem *ioremap_prot(phys_addr_t phys_addr, unsigned long size,
  47                 unsigned long prot_val)
  48 {
  49         unsigned long flags = prot_val & _CACHE_MASK;
  50         unsigned long offset, pfn, last_pfn;
  51         struct vm_struct *area;
  52         phys_addr_t last_addr;
  53         unsigned long vaddr;
  54         void __iomem *cpu_addr;
  55
  56         cpu_addr = plat_ioremap(phys_addr, size, flags);
  57         if (cpu_addr)
  58                 return cpu_addr;
  59
  60         phys_addr = fixup_bigphys_addr(phys_addr, size);
  61
  62         /* Don't allow wraparound or zero size */
  63         last_addr = phys_addr + size - 1;
  64         if (!size || last_addr < phys_addr)
  65                 return NULL;
  66
  67         /*
  68          * Map uncached objects in the low 512mb of address space using KSEG1,
  69          * otherwise map using page tables.
  70          */
  71         if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) &&
  72             flags == _CACHE_UNCACHED)
  73                 return (void __iomem *) CKSEG1ADDR(phys_addr);
  74
  75         /* Early remaps should use the unmapped regions til' VM is available */
  76         if (WARN_ON_ONCE(!slab_is_available()))
  77                 return NULL;
  78
  79         /*
  80          * Don't allow anybody to remap RAM that may be allocated by the page
  81          * allocator, since that could lead to races & data clobbering.
  82          */
  83         pfn = PFN_DOWN(phys_addr);
  84         last_pfn = PFN_DOWN(last_addr);
  85         if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
  86                                   __ioremap_check_ram) == 1) {
  87                 WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
  88                           &phys_addr, &last_addr);
  89                 return NULL;
  90         }
  91
  92         /*
  93          * Mappings have to be page-aligned
  94          */
  95         offset = phys_addr & ~PAGE_MASK;
  96         phys_addr &= PAGE_MASK;
  97         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
  98
  99         /*
 100          * Ok, go for it..
 101          */
 102         area = get_vm_area(size, VM_IOREMAP);
 103         if (!area)
 104                 return NULL;
 105         vaddr = (unsigned long)area->addr;
 106
 107         flags |= _PAGE_GLOBAL | _PAGE_PRESENT | __READABLE | __WRITEABLE;
 108         if (ioremap_page_range(vaddr, vaddr + size, phys_addr,
 109                         __pgprot(flags))) {
 110                 free_vm_area(area);
 111                 return NULL;
 112         }
 113
 114         return (void __iomem *)(vaddr + offset);
 115 }
 116 EXPORT_SYMBOL(ioremap_prot);
 117
 118 void iounmap(const volatile void __iomem *addr)
 119 {
 120         if (!plat_iounmap(addr) && !IS_KSEG1(addr))
 121                 vunmap((void *)((unsigned long)addr & PAGE_MASK));
 122 }
 123 EXPORT_SYMBOL(iounmap);