275 lines
7.0 KiB
C
275 lines
7.0 KiB
C
/*
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* arch/i386/mm/ioremap.c
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*
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* Re-map IO memory to kernel address space so that we can access it.
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* This is needed for high PCI addresses that aren't mapped in the
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* 640k-1MB IO memory area on PC's
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*
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* (C) Copyright 1995 1996 Linus Torvalds
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*/
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <asm/fixmap.h>
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#include <asm/cacheflush.h>
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#include <asm/tlbflush.h>
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#include <asm/pgtable.h>
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#define ISA_START_ADDRESS 0xa0000
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#define ISA_END_ADDRESS 0x100000
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/*
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* Generic mapping function (not visible outside):
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*/
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/*
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* Remap an arbitrary physical address space into the kernel virtual
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* address space. Needed when the kernel wants to access high addresses
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* directly.
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*
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* NOTE! We need to allow non-page-aligned mappings too: we will obviously
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* have to convert them into an offset in a page-aligned mapping, but the
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* caller shouldn't need to know that small detail.
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*/
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void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
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{
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void __iomem * addr;
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struct vm_struct * area;
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unsigned long offset, last_addr;
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pgprot_t prot;
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/* Don't allow wraparound or zero size */
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last_addr = phys_addr + size - 1;
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if (!size || last_addr < phys_addr)
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return NULL;
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/*
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* Don't remap the low PCI/ISA area, it's always mapped..
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*/
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if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
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return (void __iomem *) phys_to_virt(phys_addr);
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/*
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* Don't allow anybody to remap normal RAM that we're using..
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*/
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if (phys_addr <= virt_to_phys(high_memory - 1)) {
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char *t_addr, *t_end;
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struct page *page;
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t_addr = __va(phys_addr);
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t_end = t_addr + (size - 1);
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for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
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if(!PageReserved(page))
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return NULL;
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}
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prot = __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY
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| _PAGE_ACCESSED | flags);
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/*
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* Mappings have to be page-aligned
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*/
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offset = phys_addr & ~PAGE_MASK;
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phys_addr &= PAGE_MASK;
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size = PAGE_ALIGN(last_addr+1) - phys_addr;
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/*
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* Ok, go for it..
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*/
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area = get_vm_area(size, VM_IOREMAP | (flags << 20));
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if (!area)
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return NULL;
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area->phys_addr = phys_addr;
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addr = (void __iomem *) area->addr;
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if (ioremap_page_range((unsigned long) addr,
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(unsigned long) addr + size, phys_addr, prot)) {
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vunmap((void __force *) addr);
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return NULL;
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}
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return (void __iomem *) (offset + (char __iomem *)addr);
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}
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EXPORT_SYMBOL(__ioremap);
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/**
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* ioremap_nocache - map bus memory into CPU space
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* @offset: bus address of the memory
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* @size: size of the resource to map
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*
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* ioremap_nocache performs a platform specific sequence of operations to
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* make bus memory CPU accessible via the readb/readw/readl/writeb/
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* writew/writel functions and the other mmio helpers. The returned
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* address is not guaranteed to be usable directly as a virtual
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* address.
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*
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* This version of ioremap ensures that the memory is marked uncachable
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* on the CPU as well as honouring existing caching rules from things like
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* the PCI bus. Note that there are other caches and buffers on many
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* busses. In particular driver authors should read up on PCI writes
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*
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* It's useful if some control registers are in such an area and
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* write combining or read caching is not desirable:
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*
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* Must be freed with iounmap.
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*/
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void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
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{
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unsigned long last_addr;
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void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
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if (!p)
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return p;
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/* Guaranteed to be > phys_addr, as per __ioremap() */
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last_addr = phys_addr + size - 1;
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if (last_addr < virt_to_phys(high_memory) - 1) {
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struct page *ppage = virt_to_page(__va(phys_addr));
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unsigned long npages;
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phys_addr &= PAGE_MASK;
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/* This might overflow and become zero.. */
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last_addr = PAGE_ALIGN(last_addr);
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/* .. but that's ok, because modulo-2**n arithmetic will make
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* the page-aligned "last - first" come out right.
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*/
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npages = (last_addr - phys_addr) >> PAGE_SHIFT;
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if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
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iounmap(p);
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p = NULL;
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}
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global_flush_tlb();
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}
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return p;
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}
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EXPORT_SYMBOL(ioremap_nocache);
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/**
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* iounmap - Free a IO remapping
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* @addr: virtual address from ioremap_*
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*
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* Caller must ensure there is only one unmapping for the same pointer.
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*/
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void iounmap(volatile void __iomem *addr)
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{
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struct vm_struct *p, *o;
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if ((void __force *)addr <= high_memory)
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return;
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/*
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* __ioremap special-cases the PCI/ISA range by not instantiating a
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* vm_area and by simply returning an address into the kernel mapping
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* of ISA space. So handle that here.
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*/
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if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
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addr < phys_to_virt(ISA_END_ADDRESS))
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return;
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addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long __force)addr);
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/* Use the vm area unlocked, assuming the caller
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ensures there isn't another iounmap for the same address
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in parallel. Reuse of the virtual address is prevented by
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leaving it in the global lists until we're done with it.
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cpa takes care of the direct mappings. */
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read_lock(&vmlist_lock);
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for (p = vmlist; p; p = p->next) {
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if (p->addr == addr)
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break;
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}
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read_unlock(&vmlist_lock);
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if (!p) {
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printk("iounmap: bad address %p\n", addr);
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dump_stack();
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return;
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}
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/* Reset the direct mapping. Can block */
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if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
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change_page_attr(virt_to_page(__va(p->phys_addr)),
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get_vm_area_size(p) >> PAGE_SHIFT,
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PAGE_KERNEL);
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global_flush_tlb();
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}
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/* Finally remove it */
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o = remove_vm_area((void *)addr);
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BUG_ON(p != o || o == NULL);
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kfree(p);
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}
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EXPORT_SYMBOL(iounmap);
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void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
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{
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unsigned long offset, last_addr;
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unsigned int nrpages;
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enum fixed_addresses idx;
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/* Don't allow wraparound or zero size */
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last_addr = phys_addr + size - 1;
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if (!size || last_addr < phys_addr)
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return NULL;
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/*
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* Don't remap the low PCI/ISA area, it's always mapped..
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*/
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if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
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return phys_to_virt(phys_addr);
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/*
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* Mappings have to be page-aligned
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*/
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offset = phys_addr & ~PAGE_MASK;
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phys_addr &= PAGE_MASK;
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size = PAGE_ALIGN(last_addr) - phys_addr;
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/*
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* Mappings have to fit in the FIX_BTMAP area.
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*/
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nrpages = size >> PAGE_SHIFT;
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if (nrpages > NR_FIX_BTMAPS)
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return NULL;
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/*
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* Ok, go for it..
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*/
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idx = FIX_BTMAP_BEGIN;
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while (nrpages > 0) {
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set_fixmap(idx, phys_addr);
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phys_addr += PAGE_SIZE;
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--idx;
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--nrpages;
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}
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return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
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}
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void __init bt_iounmap(void *addr, unsigned long size)
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{
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unsigned long virt_addr;
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unsigned long offset;
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unsigned int nrpages;
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enum fixed_addresses idx;
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virt_addr = (unsigned long)addr;
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if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
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return;
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offset = virt_addr & ~PAGE_MASK;
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nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
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idx = FIX_BTMAP_BEGIN;
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while (nrpages > 0) {
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clear_fixmap(idx);
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--idx;
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--nrpages;
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}
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}
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