mm/ioremap.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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/mm.h>
#include <linux/sched.h>
#include <linux/io.h>
#include <linux/export.h>
#include <asm/cacheflush.h>

#include "pgalloc-track.h"

#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
static bool __ro_after_init iomap_max_page_shift = PAGE_SHIFT;

static int __init set_nohugeiomap(char *str)
{
	iomap_max_page_shift = P4D_SHIFT;
	return 0;
}
early_param("nohugeiomap", set_nohugeiomap);
#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
static const bool iomap_max_page_shift = PAGE_SHIFT;
#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */

int ioremap_page_range(unsigned long addr,
		       unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
	return vmap_range(addr, end, phys_addr, prot, iomap_max_page_shift);
}

#ifdef CONFIG_GENERIC_IOREMAP
void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
{
	unsigned long offset, vaddr;
	phys_addr_t last_addr;
	struct vm_struct *area;

	/* Disallow wrap-around or zero size */
	last_addr = addr + size - 1;
	if (!size || last_addr < addr)
		return NULL;

	/* Page-align mappings */
	offset = addr & (~PAGE_MASK);
	addr -= offset;
	size = PAGE_ALIGN(size + offset);

	area = get_vm_area_caller(size, VM_IOREMAP,
			__builtin_return_address(0));
	if (!area)
		return NULL;
	vaddr = (unsigned long)area->addr;

	if (ioremap_page_range(vaddr, vaddr + size, addr, __pgprot(prot))) {
		free_vm_area(area);
		return NULL;
	}

	return (void __iomem *)(vaddr + offset);
}
EXPORT_SYMBOL(ioremap_prot);

void iounmap(volatile void __iomem *addr)
{
	vunmap((void *)((unsigned long)addr & PAGE_MASK));
}
EXPORT_SYMBOL(iounmap);
#endif /* CONFIG_GENERIC_IOREMAP */