2 * linux/arch/arm/mm/ioremap.c
4 * Re-map IO memory to kernel address space so that we can access it.
6 * (C) Copyright 1995 1996 Linus Torvalds
8 * Hacked for ARM by Phil Blundell <philb@gnu.org>
9 * Hacked to allow all architectures to build, and various cleanups
12 * This allows a driver to remap an arbitrary region of bus memory into
13 * virtual space. One should *only* use readl, writel, memcpy_toio and
14 * so on with such remapped areas.
16 * Because the ARM only has a 32-bit address space we can't address the
17 * whole of the (physical) PCI space at once. PCI huge-mode addressing
18 * allows us to circumvent this restriction by splitting PCI space into
19 * two 2GB chunks and mapping only one at a time into processor memory.
20 * We use MMU protection domains to trap any attempt to access the bank
21 * that is not currently mapped. (This isn't fully implemented yet.)
23 #include <linux/errno.h>
25 #include <linux/vmalloc.h>
27 #include <asm/cacheflush.h>
29 #include <asm/tlbflush.h>
32 remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
33 unsigned long phys_addr, pgprot_t pgprot)
41 BUG_ON(address >= end);
46 set_pte(pte, pfn_pte(phys_addr >> PAGE_SHIFT, pgprot));
48 phys_addr += PAGE_SIZE;
50 } while (address && (address < end));
54 printk("remap_area_pte: page already exists\n");
59 remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
60 unsigned long phys_addr, unsigned long flags)
65 address &= ~PGDIR_MASK;
72 BUG_ON(address >= end);
74 pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
76 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
79 remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
80 address = (address + PMD_SIZE) & PMD_MASK;
82 } while (address && (address < end));
87 remap_area_pages(unsigned long start, unsigned long phys_addr,
88 unsigned long size, unsigned long flags)
90 unsigned long address = start;
91 unsigned long end = start + size;
96 dir = pgd_offset(&init_mm, address);
97 BUG_ON(address >= end);
98 spin_lock(&init_mm.page_table_lock);
100 pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
105 if (remap_area_pmd(pmd, address, end - address,
106 phys_addr + address, flags)) {
111 address = (address + PGDIR_SIZE) & PGDIR_MASK;
113 } while (address && (address < end));
115 spin_unlock(&init_mm.page_table_lock);
116 flush_cache_vmap(start, end);
121 * Remap an arbitrary physical address space into the kernel virtual
122 * address space. Needed when the kernel wants to access high addresses
125 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
126 * have to convert them into an offset in a page-aligned mapping, but the
127 * caller shouldn't need to know that small detail.
129 * 'flags' are the extra L_PTE_ flags that you want to specify for this
130 * mapping. See include/asm-arm/proc-armv/pgtable.h for more information.
133 __ioremap(unsigned long phys_addr, size_t size, unsigned long flags,
137 struct vm_struct * area;
138 unsigned long offset, last_addr;
140 /* Don't allow wraparound or zero size */
141 last_addr = phys_addr + size - 1;
142 if (!size || last_addr < phys_addr)
146 * Mappings have to be page-aligned
148 offset = phys_addr & ~PAGE_MASK;
149 phys_addr &= PAGE_MASK;
150 size = PAGE_ALIGN(last_addr) - phys_addr;
155 area = get_vm_area(size, VM_IOREMAP);
159 if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
163 return (void *) (offset + (char *)addr);
166 void __iounmap(void *addr)
168 vfree((void *) (PAGE_MASK & (unsigned long) addr));