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  * (C) Copyright 2005, 2006 Paul Mundt
  10  *
  11  * This file is subject to the terms and conditions of the GNU General
  12  * Public License. See the file "COPYING" in the main directory of this
  13  * archive for more details.
  14  */
  15 #include <linux/vmalloc.h>
  16 #include <linux/module.h>
  17 #include <linux/mm.h>
  18 #include <linux/pci.h>
  19 #include <linux/io.h>
  20 #include <asm/page.h>
  21 #include <asm/pgalloc.h>
  22 #include <asm/addrspace.h>
  23 #include <asm/cacheflush.h>
  24 #include <asm/tlbflush.h>
  25
  26 /*
  27  * Remap an arbitrary physical address space into the kernel virtual
  28  * address space. Needed when the kernel wants to access high addresses
  29  * directly.
  30  *
  31  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  32  * have to convert them into an offset in a page-aligned mapping, but the
  33  * caller shouldn't need to know that small detail.
  34  */
  35 void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
  36                         unsigned long flags)
  37 {
  38         struct vm_struct * area;
  39         unsigned long offset, last_addr, addr, orig_addr;
  40         pgprot_t pgprot;
  41
  42         /* Don't allow wraparound or zero size */
  43         last_addr = phys_addr + size - 1;
  44         if (!size || last_addr < phys_addr)
  45                 return NULL;
  46
  47         /*
  48          * If we're on an SH7751 or SH7780 PCI controller, PCI memory is
  49          * mapped at the end of the address space (typically 0xfd000000)
  50          * in a non-translatable area, so mapping through page tables for
  51          * this area is not only pointless, but also fundamentally
  52          * broken. Just return the physical address instead.
  53          *
  54          * For boards that map a small PCI memory aperture somewhere in
  55          * P1/P2 space, ioremap() will already do the right thing,
  56          * and we'll never get this far.
  57          */
  58         if (is_pci_memaddr(phys_addr) && is_pci_memaddr(last_addr))
  59                 return (void __iomem *)phys_addr;
  60
  61         /*
  62          * Don't allow anybody to remap normal RAM that we're using..
  63          */
  64         if (phys_addr < virt_to_phys(high_memory))
  65                 return NULL;
  66
  67         /*
  68          * Mappings have to be page-aligned
  69          */
  70         offset = phys_addr & ~PAGE_MASK;
  71         phys_addr &= PAGE_MASK;
  72         size = PAGE_ALIGN(last_addr+1) - phys_addr;
  73
  74         /*
  75          * Ok, go for it..
  76          */
  77         area = get_vm_area(size, VM_IOREMAP);
  78         if (!area)
  79                 return NULL;
  80         area->phys_addr = phys_addr;
  81         orig_addr = addr = (unsigned long)area->addr;
  82
  83 #ifdef CONFIG_32BIT
  84         /*
  85          * First try to remap through the PMB once a valid VMA has been
  86          * established. Smaller allocations (or the rest of the size
  87          * remaining after a PMB mapping due to the size not being
  88          * perfectly aligned on a PMB size boundary) are then mapped
  89          * through the UTLB using conventional page tables.
  90          *
  91          * PMB entries are all pre-faulted.
  92          */
  93         if (unlikely(size >= 0x1000000)) {
  94                 unsigned long mapped = pmb_remap(addr, phys_addr, size, flags);
  95
  96                 if (likely(mapped)) {
  97                         addr            += mapped;
  98                         phys_addr       += mapped;
  99                         size            -= mapped;
 100                 }
 101         }
 102 #endif
 103
 104         pgprot = __pgprot(pgprot_val(PAGE_KERNEL_NOCACHE) | flags);
 105         if (likely(size))
 106                 if (ioremap_page_range(addr, addr + size, phys_addr, pgprot)) {
 107                         vunmap((void *)orig_addr);
 108                         return NULL;
 109                 }
 110
 111         return (void __iomem *)(offset + (char *)orig_addr);
 112 }
 113 EXPORT_SYMBOL(__ioremap);
 114
 115 void __iounmap(void __iomem *addr)
 116 {
 117         unsigned long vaddr = (unsigned long __force)addr;
 118         struct vm_struct *p;
 119
 120         if (PXSEG(vaddr) < P3SEG || is_pci_memaddr(vaddr))
 121                 return;
 122
 123 #ifdef CONFIG_32BIT
 124         /*
 125          * Purge any PMB entries that may have been established for this
 126          * mapping, then proceed with conventional VMA teardown.
 127          *
 128          * XXX: Note that due to the way that remove_vm_area() does
 129          * matching of the resultant VMA, we aren't able to fast-forward
 130          * the address past the PMB space until the end of the VMA where
 131          * the page tables reside. As such, unmap_vm_area() will be
 132          * forced to linearly scan over the area until it finds the page
 133          * tables where PTEs that need to be unmapped actually reside,
 134          * which is far from optimal. Perhaps we need to use a separate
 135          * VMA for the PMB mappings?
 136          *                                      -- PFM.
 137          */
 138         pmb_unmap(vaddr);
 139 #endif
 140
 141         p = remove_vm_area((void *)(vaddr & PAGE_MASK));
 142         if (!p) {
 143                 printk(KERN_ERR "%s: bad address %p\n", __FUNCTION__, addr);
 144                 return;
 145         }
 146
 147         kfree(p);
 148 }
 149 EXPORT_SYMBOL(__iounmap);