arch/i386/mm/ioremap.c - third_party/linux - Git at Google

 /*
  * arch/i386/mm/ioremap.c
  *
  * Re-map IO memory to kernel address space so that we can access it.
  * This is needed for high PCI addresses that aren't mapped in the
  * 640k-1MB IO memory area on PC's
  *
  * (C) Copyright 1995 1996 Linus Torvalds
  */

 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <asm/io.h>
 #include <asm/fixmap.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/pgtable.h>

 static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
 	unsigned long phys_addr, unsigned long flags)
 {
 	unsigned long end;
 	unsigned long pfn;

 	address &= ~PMD_MASK;
 	end = address + size;
 	if (end > PMD_SIZE)
 		end = PMD_SIZE;
 	if (address >= end)
 		BUG();
 	pfn = phys_addr >> PAGE_SHIFT;
 	do {
 		if (!pte_none(*pte)) {
 			printk("remap_area_pte: page already exists\n");
 			BUG();
 		}
 		set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT | _PAGE_RW |
 					_PAGE_DIRTY | _PAGE_ACCESSED | flags)));
 		address += PAGE_SIZE;
 		pfn++;
 		pte++;
 	} while (address && (address < end));
 }

 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;

 	address &= ~PGDIR_MASK;
 	end = address + size;
 	if (end > PGDIR_SIZE)
 		end = PGDIR_SIZE;
 	phys_addr -= address;
 	if (address >= end)
 		BUG();
 	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, flags);
 		address = (address + PMD_SIZE) & PMD_MASK;
 		pmd++;
 	} while (address && (address < end));
 	return 0;
 }

 static int remap_area_pages(unsigned long address, unsigned long phys_addr,
 				 unsigned long size, unsigned long flags)
 {
 	int error;
 	pgd_t * dir;
 	unsigned long end = address + size;

 	phys_addr -= address;
 	dir = pgd_offset(&init_mm, address);
 	flush_cache_all();
 	if (address >= end)
 		BUG();
 	spin_lock(&init_mm.page_table_lock);
 	do {
 		pud_t *pud;
 		pmd_t *pmd;

 		error = -ENOMEM;
 		pud = pud_alloc(&init_mm, dir, address);
 		if (!pud)
 			break;
 		pmd = pmd_alloc(&init_mm, pud, address);
 		if (!pmd)
 			break;
 		if (remap_area_pmd(pmd, address, end - address,
 					 phys_addr + address, flags))
 			break;
 		error = 0;
 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
 		dir++;
 	} while (address && (address < end));
 	spin_unlock(&init_mm.page_table_lock);
 	flush_tlb_all();
 	return error;
 }

 /*
  * Generic mapping function (not visible outside):
  */

 /*
  * 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.
  */
 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 {
 	void __iomem * 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;

 	/*
 	 * Don't remap the low PCI/ISA area, it's always mapped..
 	 */
 	if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 		return (void __iomem *) phys_to_virt(phys_addr);

 	/*
 	 * Don't allow anybody to remap normal RAM that we're using..
 	 */
 	if (phys_addr <= virt_to_phys(high_memory - 1)) {
 		char *t_addr, *t_end;
 		struct page *page;

 		t_addr = __va(phys_addr);
 		t_end = t_addr + (size - 1);

 		for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 			if(!PageReserved(page))
 				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 | (flags << 20));
 	if (!area)
 		return NULL;
 	area->phys_addr = phys_addr;
 	addr = (void __iomem *) area->addr;
 	if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 		vunmap((void __force *) addr);
 		return NULL;
 	}
 	return (void __iomem *) (offset + (char __iomem *)addr);
 }


 /**
  * ioremap_nocache     -   map bus memory into CPU space
  * @offset:    bus address of the memory
  * @size:      size of the resource to map
  *
  * ioremap_nocache performs a platform specific sequence of operations to
  * make bus memory CPU accessible via the readb/readw/readl/writeb/
  * writew/writel functions and the other mmio helpers. The returned
  * address is not guaranteed to be usable directly as a virtual
  * address.
  *
  * This version of ioremap ensures that the memory is marked uncachable
  * on the CPU as well as honouring existing caching rules from things like
  * the PCI bus. Note that there are other caches and buffers on many
  * busses. In particular driver authors should read up on PCI writes
  *
  * It's useful if some control registers are in such an area and
  * write combining or read caching is not desirable:
  *
  * Must be freed with iounmap.
  */

 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 {
 	unsigned long last_addr;
 	void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
 	if (!p)
 		return p;

 	/* Guaranteed to be > phys_addr, as per __ioremap() */
 	last_addr = phys_addr + size - 1;

 	if (last_addr < virt_to_phys(high_memory) - 1) {
 		struct page *ppage = virt_to_page(__va(phys_addr));
 		unsigned long npages;

 		phys_addr &= PAGE_MASK;

 		/* This might overflow and become zero.. */
 		last_addr = PAGE_ALIGN(last_addr);

 		/* .. but that's ok, because modulo-2**n arithmetic will make
 	 	* the page-aligned "last - first" come out right.
 	 	*/
 		npages = (last_addr - phys_addr) >> PAGE_SHIFT;

 		if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
 			iounmap(p);
 			p = NULL;
 		}
 		global_flush_tlb();
 	}

 	return p;
 }

 void iounmap(volatile void __iomem *addr)
 {
 	struct vm_struct *p;
 	if ((void __force *) addr <= high_memory)
 		return;
 	p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 	if (!p) {
 		printk("__iounmap: bad address %p\n", addr);
 		return;
 	}

 	if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
 		/* p->size includes the guard page, but cpa doesn't like that */
 		change_page_attr(virt_to_page(__va(p->phys_addr)),
 				 (p->size - PAGE_SIZE) >> PAGE_SHIFT,
 				 PAGE_KERNEL);
 		global_flush_tlb();
 	}
 	kfree(p);
 }

 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 {
 	unsigned long offset, last_addr;
 	unsigned int nrpages;
 	enum fixed_addresses idx;

 	/* Don't allow wraparound or zero size */
 	last_addr = phys_addr + size - 1;
 	if (!size || last_addr < phys_addr)
 		return NULL;

 	/*
 	 * Don't remap the low PCI/ISA area, it's always mapped..
 	 */
 	if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 		return phys_to_virt(phys_addr);

 	/*
 	 * Mappings have to be page-aligned
 	 */
 	offset = phys_addr & ~PAGE_MASK;
 	phys_addr &= PAGE_MASK;
 	size = PAGE_ALIGN(last_addr) - phys_addr;

 	/*
 	 * Mappings have to fit in the FIX_BTMAP area.
 	 */
 	nrpages = size >> PAGE_SHIFT;
 	if (nrpages > NR_FIX_BTMAPS)
 		return NULL;

 	/*
 	 * Ok, go for it..
 	 */
 	idx = FIX_BTMAP_BEGIN;
 	while (nrpages > 0) {
 		set_fixmap(idx, phys_addr);
 		phys_addr += PAGE_SIZE;
 		--idx;
 		--nrpages;
 	}
 	return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
 }

 void __init bt_iounmap(void *addr, unsigned long size)
 {
 	unsigned long virt_addr;
 	unsigned long offset;
 	unsigned int nrpages;
 	enum fixed_addresses idx;

 	virt_addr = (unsigned long)addr;
 	if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
 		return;
 	offset = virt_addr & ~PAGE_MASK;
 	nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;

 	idx = FIX_BTMAP_BEGIN;
 	while (nrpages > 0) {
 		clear_fixmap(idx);
 		--idx;
 		--nrpages;
 	}
 }
	/*
	* arch/i386/mm/ioremap.c
	*
	* Re-map IO memory to kernel address space so that we can access it.
	* This is needed for high PCI addresses that aren't mapped in the
	* 640k-1MB IO memory area on PC's
	*
	* (C) Copyright 1995 1996 Linus Torvalds
	*/

	#include <linux/vmalloc.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <asm/io.h>
	#include <asm/fixmap.h>
	#include <asm/cacheflush.h>
	#include <asm/tlbflush.h>
	#include <asm/pgtable.h>

	static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
	unsigned long phys_addr, unsigned long flags)
	{
	unsigned long end;
	unsigned long pfn;

	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
	end = PMD_SIZE;
	if (address >= end)
	BUG();
	pfn = phys_addr >> PAGE_SHIFT;
	do {
	if (!pte_none(*pte)) {
	printk("remap_area_pte: page already exists\n");
	BUG();
	}
	set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT \| _PAGE_RW \|
	_PAGE_DIRTY \| _PAGE_ACCESSED \| flags)));
	address += PAGE_SIZE;
	pfn++;
	pte++;
	} while (address && (address < end));
	}

	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;

	address &= ~PGDIR_MASK;
	end = address + size;
	if (end > PGDIR_SIZE)
	end = PGDIR_SIZE;
	phys_addr -= address;
	if (address >= end)
	BUG();
	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, flags);
	address = (address + PMD_SIZE) & PMD_MASK;
	pmd++;
	} while (address && (address < end));
	return 0;
	}

	static int remap_area_pages(unsigned long address, unsigned long phys_addr,
	unsigned long size, unsigned long flags)
	{
	int error;
	pgd_t * dir;
	unsigned long end = address + size;

	phys_addr -= address;
	dir = pgd_offset(&init_mm, address);
	flush_cache_all();
	if (address >= end)
	BUG();
	spin_lock(&init_mm.page_table_lock);
	do {
	pud_t *pud;
	pmd_t *pmd;

	error = -ENOMEM;
	pud = pud_alloc(&init_mm, dir, address);
	if (!pud)
	break;
	pmd = pmd_alloc(&init_mm, pud, address);
	if (!pmd)
	break;
	if (remap_area_pmd(pmd, address, end - address,
	phys_addr + address, flags))
	break;
	error = 0;
	address = (address + PGDIR_SIZE) & PGDIR_MASK;
	dir++;
	} while (address && (address < end));
	spin_unlock(&init_mm.page_table_lock);
	flush_tlb_all();
	return error;
	}

	/*
	* Generic mapping function (not visible outside):
	*/

	/*
	* 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.
	*/
	void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
	{
	void __iomem * 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;

	/*
	* Don't remap the low PCI/ISA area, it's always mapped..
	*/
	if (phys_addr >= 0xA0000 && last_addr < 0x100000)
	return (void __iomem *) phys_to_virt(phys_addr);

	/*
	* Don't allow anybody to remap normal RAM that we're using..
	*/
	if (phys_addr <= virt_to_phys(high_memory - 1)) {
	char t_addr, t_end;
	struct page *page;

	t_addr = __va(phys_addr);
	t_end = t_addr + (size - 1);

	for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
	if(!PageReserved(page))
	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 \| (flags << 20));
	if (!area)
	return NULL;
	area->phys_addr = phys_addr;
	addr = (void __iomem *) area->addr;
	if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
	vunmap((void __force *) addr);
	return NULL;
	}
	return (void __iomem ) (offset + (char __iomem )addr);
	}


	/**
	* ioremap_nocache - map bus memory into CPU space
	* @offset: bus address of the memory
	* @size: size of the resource to map
	*
	* ioremap_nocache performs a platform specific sequence of operations to
	* make bus memory CPU accessible via the readb/readw/readl/writeb/
	* writew/writel functions and the other mmio helpers. The returned
	* address is not guaranteed to be usable directly as a virtual
	* address.
	*
	* This version of ioremap ensures that the memory is marked uncachable
	* on the CPU as well as honouring existing caching rules from things like
	* the PCI bus. Note that there are other caches and buffers on many
	* busses. In particular driver authors should read up on PCI writes
	*
	* It's useful if some control registers are in such an area and
	* write combining or read caching is not desirable:
	*
	* Must be freed with iounmap.
	*/

	void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
	{
	unsigned long last_addr;
	void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
	if (!p)
	return p;

	/* Guaranteed to be > phys_addr, as per __ioremap() */
	last_addr = phys_addr + size - 1;

	if (last_addr < virt_to_phys(high_memory) - 1) {
	struct page *ppage = virt_to_page(__va(phys_addr));
	unsigned long npages;

	phys_addr &= PAGE_MASK;

	/* This might overflow and become zero.. */
	last_addr = PAGE_ALIGN(last_addr);

	/* .. but that's ok, because modulo-2**n arithmetic will make
	* the page-aligned "last - first" come out right.
	*/
	npages = (last_addr - phys_addr) >> PAGE_SHIFT;

	if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
	iounmap(p);
	p = NULL;
	}
	global_flush_tlb();
	}

	return p;
	}

	void iounmap(volatile void __iomem *addr)
	{
	struct vm_struct *p;
	if ((void __force *) addr <= high_memory)
	return;
	p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
	if (!p) {
	printk("__iounmap: bad address %p\n", addr);
	return;
	}

	if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
	/* p->size includes the guard page, but cpa doesn't like that */
	change_page_attr(virt_to_page(__va(p->phys_addr)),
	(p->size - PAGE_SIZE) >> PAGE_SHIFT,
	PAGE_KERNEL);
	global_flush_tlb();
	}
	kfree(p);
	}

	void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
	{
	unsigned long offset, last_addr;
	unsigned int nrpages;
	enum fixed_addresses idx;

	/* Don't allow wraparound or zero size */
	last_addr = phys_addr + size - 1;
	if (!size \|\| last_addr < phys_addr)
	return NULL;

	/*
	* Don't remap the low PCI/ISA area, it's always mapped..
	*/
	if (phys_addr >= 0xA0000 && last_addr < 0x100000)
	return phys_to_virt(phys_addr);

	/*
	* Mappings have to be page-aligned
	*/
	offset = phys_addr & ~PAGE_MASK;
	phys_addr &= PAGE_MASK;
	size = PAGE_ALIGN(last_addr) - phys_addr;

	/*
	* Mappings have to fit in the FIX_BTMAP area.
	*/
	nrpages = size >> PAGE_SHIFT;
	if (nrpages > NR_FIX_BTMAPS)
	return NULL;

	/*
	* Ok, go for it..
	*/
	idx = FIX_BTMAP_BEGIN;
	while (nrpages > 0) {
	set_fixmap(idx, phys_addr);
	phys_addr += PAGE_SIZE;
	--idx;
	--nrpages;
	}
	return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
	}

	void __init bt_iounmap(void *addr, unsigned long size)
	{
	unsigned long virt_addr;
	unsigned long offset;
	unsigned int nrpages;
	enum fixed_addresses idx;

	virt_addr = (unsigned long)addr;
	if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
	return;
	offset = virt_addr & ~PAGE_MASK;
	nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;

	idx = FIX_BTMAP_BEGIN;
	while (nrpages > 0) {
	clear_fixmap(idx);
	--idx;
	--nrpages;
	}
	}