x86/mm/mtrr, pat: Document Write Combining MTRR type effects on PAT / non-PAT pages

[deliverable/linux.git] / include / linux / io.h

/*
 * Copyright 2006 PathScale, Inc.  All Rights Reserved.
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License
 * 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, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#ifndef _LINUX_IO_H
#define _LINUX_IO_H

#include <linux/types.h>
#include <asm/io.h>
#include <asm/page.h>

struct device;

__visible void __iowrite32_copy(void __iomem *to, const void *from, size_t count);
void __iowrite64_copy(void __iomem *to, const void *from, size_t count);

#ifdef CONFIG_MMU
int ioremap_page_range(unsigned long addr, unsigned long end,
		       phys_addr_t phys_addr, pgprot_t prot);
#else
static inline int ioremap_page_range(unsigned long addr, unsigned long end,
				     phys_addr_t phys_addr, pgprot_t prot)
{
	return 0;
}
#endif

#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
void __init ioremap_huge_init(void);
int arch_ioremap_pud_supported(void);
int arch_ioremap_pmd_supported(void);
#else
static inline void ioremap_huge_init(void) { }
#endif

/*
 * Managed iomap interface
 */
#ifdef CONFIG_HAS_IOPORT_MAP
void __iomem * devm_ioport_map(struct device *dev, unsigned long port,
			       unsigned int nr);
void devm_ioport_unmap(struct device *dev, void __iomem *addr);
#else
static inline void __iomem *devm_ioport_map(struct device *dev,
					     unsigned long port,
					     unsigned int nr)
{
	return NULL;
}

static inline void devm_ioport_unmap(struct device *dev, void __iomem *addr)
{
}
#endif

#define IOMEM_ERR_PTR(err) (__force void __iomem *)ERR_PTR(err)

void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
			   resource_size_t size);
void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
				   resource_size_t size);
void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
				   resource_size_t size);
void devm_iounmap(struct device *dev, void __iomem *addr);
int check_signature(const volatile void __iomem *io_addr,
			const unsigned char *signature, int length);
void devm_ioremap_release(struct device *dev, void *res);

/*
 * Some systems do not have legacy ISA devices.
 * /dev/port is not a valid interface on these systems.
 * So for those archs, <asm/io.h> should define the following symbol.
 */
#ifndef arch_has_dev_port
#define arch_has_dev_port()     (1)
#endif

/*
 * Some systems (x86 without PAT) have a somewhat reliable way to mark a
 * physical address range such that uncached mappings will actually
 * end up write-combining.  This facility should be used in conjunction
 * with pgprot_writecombine, ioremap-wc, or set_memory_wc, since it has
 * no effect if the per-page mechanisms are functional.
 * (On x86 without PAT, these functions manipulate MTRRs.)
 *
 * arch_phys_del_wc(0) or arch_phys_del_wc(any error code) is guaranteed
 * to have no effect.
 */
#ifndef arch_phys_wc_add
static inline int __must_check arch_phys_wc_add(unsigned long base,
						unsigned long size)
{
	return 0;  /* It worked (i.e. did nothing). */
}

static inline void arch_phys_wc_del(int handle)
{
}

#define arch_phys_wc_add arch_phys_wc_add
#endif

#endif /* _LINUX_IO_H */