1. 根目录:
2. arch
3. arm64
4. mm
5. ioremap.c

/*
 * Based on arch/arm/mm/ioremap.c
 *
 * (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
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/export.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/io.h>

#include <asm/fixmap.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>

static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size,
				      pgprot_t prot, void *caller)
{
	unsigned long last_addr;
	unsigned long offset = phys_addr & ~PAGE_MASK;
	int err;
	unsigned long addr;
	struct vm_struct *area;

	/*
	 * Page align the mapping address and size, taking account of any
	 * offset.
	 */
	phys_addr &= PAGE_MASK;
	size = PAGE_ALIGN(size + offset);

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

	/*
	 * Don't allow RAM to be mapped.
	 */
	if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr))))
		return NULL;

	area = get_vm_area_caller(size, VM_IOREMAP, caller);
	if (!area)
		return NULL;
	addr = (unsigned long)area->addr;
	area->phys_addr = phys_addr;

	err = ioremap_page_range(addr, addr + size, phys_addr, prot);
	if (err) {
		vunmap((void *)addr);
		return NULL;
	}

	return (void __iomem *)(offset + addr);
}

void __iomem *__ioremap(phys_addr_t phys_addr, size_t size, pgprot_t prot)
{
	return __ioremap_caller(phys_addr, size, prot,
				__builtin_return_address(0));
}
EXPORT_SYMBOL(__ioremap);

void __iounmap(volatile void __iomem *io_addr)
{
	unsigned long addr = (unsigned long)io_addr & PAGE_MASK;

	/*
	 * We could get an address outside vmalloc range in case
	 * of ioremap_cache() reusing a RAM mapping.
	 */
	if (VMALLOC_START <= addr && addr < VMALLOC_END)
		vunmap((void *)addr);
}
EXPORT_SYMBOL(__iounmap);

void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
{
	/* For normal memory we already have a cacheable mapping. */
	if (pfn_valid(__phys_to_pfn(phys_addr)))
		return (void __iomem *)__phys_to_virt(phys_addr);

	return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL),
				__builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_cache);

/*
 * Must be called after early_fixmap_init
 */
void __init early_ioremap_init(void)
{
	early_ioremap_setup();
}