diff options
Diffstat (limited to 'arch/arm/mm/ioremap.c')
| -rw-r--r-- | arch/arm/mm/ioremap.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c new file mode 100644 index 000000000000..00bb8fd37a59 --- /dev/null +++ b/arch/arm/mm/ioremap.c @@ -0,0 +1,172 @@ +/* + * linux/arch/arm/mm/ioremap.c + * + * Re-map IO memory to kernel address space so that we can access it. + * + * (C) Copyright 1995 1996 Linus Torvalds + * + * Hacked for ARM by Phil Blundell <philb@gnu.org> + * Hacked to allow all architectures to build, and various cleanups + * by Russell King + * + * This allows a driver to remap an arbitrary region of bus memory into + * virtual space. One should *only* use readl, writel, memcpy_toio and + * so on with such remapped areas. + * + * Because the ARM only has a 32-bit address space we can't address the + * whole of the (physical) PCI space at once. PCI huge-mode addressing + * allows us to circumvent this restriction by splitting PCI space into + * two 2GB chunks and mapping only one at a time into processor memory. + * We use MMU protection domains to trap any attempt to access the bank + * that is not currently mapped. (This isn't fully implemented yet.) + */ +#include <linux/module.h> +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/vmalloc.h> + +#include <asm/cacheflush.h> +#include <asm/io.h> +#include <asm/tlbflush.h> + +static inline void +remap_area_pte(pte_t * pte, unsigned long address, unsigned long size, + unsigned long phys_addr, pgprot_t pgprot) +{ + unsigned long end; + + address &= ~PMD_MASK; + end = address + size; + if (end > PMD_SIZE) + end = PMD_SIZE; + BUG_ON(address >= end); + do { + if (!pte_none(*pte)) + goto bad; + + set_pte(pte, pfn_pte(phys_addr >> PAGE_SHIFT, pgprot)); + address += PAGE_SIZE; + phys_addr += PAGE_SIZE; + pte++; + } while (address && (address < end)); + return; + + bad: + printk("remap_area_pte: page already exists\n"); + BUG(); +} + +static inline int +remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size, + unsigned long phys_addr, unsigned long flags) +{ + unsigned long end; + pgprot_t pgprot; + + address &= ~PGDIR_MASK; + end = address + size; + + if (end > PGDIR_SIZE) + end = PGDIR_SIZE; + + phys_addr -= address; + BUG_ON(address >= end); + + pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags); + do { + pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address); + if (!pte) + return -ENOMEM; + remap_area_pte(pte, address, end - address, address + phys_addr, pgprot); + address = (address + PMD_SIZE) & PMD_MASK; + pmd++; + } while (address && (address < end)); + return 0; +} + +static int +remap_area_pages(unsigned long start, unsigned long phys_addr, + unsigned long size, unsigned long flags) +{ + unsigned long address = start; + unsigned long end = start + size; + int err = 0; + pgd_t * dir; + + phys_addr -= address; + dir = pgd_offset(&init_mm, address); + BUG_ON(address >= end); + spin_lock(&init_mm.page_table_lock); + do { + pmd_t *pmd = pmd_alloc(&init_mm, dir, address); + if (!pmd) { + err = -ENOMEM; + break; + } + if (remap_area_pmd(pmd, address, end - address, + phys_addr + address, flags)) { + err = -ENOMEM; + break; + } + + address = (address + PGDIR_SIZE) & PGDIR_MASK; + dir++; + } while (address && (address < end)); + + spin_unlock(&init_mm.page_table_lock); + flush_cache_vmap(start, end); + return err; +} + +/* + * Remap an arbitrary physical address space into the kernel virtual + * address space. Needed when the kernel wants to access high addresses + * directly. + * + * NOTE! We need to allow non-page-aligned mappings too: we will obviously + * have to convert them into an offset in a page-aligned mapping, but the + * caller shouldn't need to know that small detail. + * + * 'flags' are the extra L_PTE_ flags that you want to specify for this + * mapping. See include/asm-arm/proc-armv/pgtable.h for more information. + */ +void __iomem * +__ioremap(unsigned long phys_addr, size_t size, unsigned long flags, + unsigned long align) +{ + void * addr; + struct vm_struct * area; + unsigned long offset, last_addr; + + /* Don't allow wraparound or zero size */ + last_addr = phys_addr + size - 1; + if (!size || last_addr < phys_addr) + return NULL; + + /* + * Mappings have to be page-aligned + */ + offset = phys_addr & ~PAGE_MASK; + phys_addr &= PAGE_MASK; + size = PAGE_ALIGN(last_addr + 1) - phys_addr; + + /* + * Ok, go for it.. + */ + area = get_vm_area(size, VM_IOREMAP); + if (!area) + return NULL; + addr = area->addr; + if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) { + vfree(addr); + return NULL; + } + return (void __iomem *) (offset + (char *)addr); +} +EXPORT_SYMBOL(__ioremap); + +void __iounmap(void __iomem *addr) +{ + vfree((void *) (PAGE_MASK & (unsigned long) addr)); +} +EXPORT_SYMBOL(__iounmap); |