ioremap.c

/*
 * arch/sh/mm/ioremap.c
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 * (C) Copyright 2005 - 2010  Paul Mundt
 *
 * 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
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License. See the file "COPYING" in the main directory of this
 * archive for more details.
 */
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/pci.h>
#include <linux/io.h>
#include <asm/io_trapped.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/addrspace.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/mmu.h>
#include "ioremap.h"

/*
 * On 32-bit SH, we traditionally have the whole physical address space mapped
 * at all times (as MIPS does), so "ioremap()" and "iounmap()" do not need to do
 * anything but place the address in the proper segment.  This is true for P1
 * and P2 addresses, as well as some P3 ones.  However, most of the P3 addresses
 * and newer cores using extended addressing need to map through page tables, so
 * the ioremap() implementation becomes a bit more complicated.
 */
#ifdef CONFIG_29BIT
static void __iomem *
__ioremap_29bit(phys_addr_t offset, unsigned long size, pgprot_t prot)
{
	phys_addr_t last_addr = offset + size - 1;

	/*
	 * For P1 and P2 space this is trivial, as everything is already
	 * mapped. Uncached access for P1 addresses are done through P2.
	 * In the P3 case or for addresses outside of the 29-bit space,
	 * mapping must be done by the PMB or by using page tables.
	 */
	if (likely(PXSEG(offset) < P3SEG && PXSEG(last_addr) < P3SEG)) {
		u64 flags = pgprot_val(prot);

		/*
		 * Anything using the legacy PTEA space attributes needs
		 * to be kicked down to page table mappings.
		 */
		if (unlikely(flags & _PAGE_PCC_MASK))
			return NULL;
		if (unlikely(flags & _PAGE_CACHABLE))
			return (void __iomem *)P1SEGADDR(offset);

		return (void __iomem *)P2SEGADDR(offset);
	}

	/* P4 above the store queues are always mapped. */
	if (unlikely(offset >= P3_ADDR_MAX))
		return (void __iomem *)P4SEGADDR(offset);

	return NULL;
}
#else
#define __ioremap_29bit(offset, size, prot)		NULL
#endif /* CONFIG_29BIT */

void __iomem __ref *ioremap_prot(phys_addr_t phys_addr, size_t size,
				 pgprot_t pgprot)
{
	void __iomem *mapped;

	mapped = __ioremap_trapped(phys_addr, size);
	if (mapped)
		return mapped;

	mapped = __ioremap_29bit(phys_addr, size, pgprot);
	if (mapped)
		return mapped;

	/*
	 * If we can't yet use the regular approach, go the fixmap route.
	 */
	if (!mem_init_done)
		return ioremap_fixed(phys_addr, size, pgprot);

	/*
	 * First try to remap through the PMB.
	 * PMB entries are all pre-faulted.
	 */
	mapped = pmb_remap_caller(phys_addr, size, pgprot,
			__builtin_return_address(0));
	if (mapped && !IS_ERR(mapped))
		return mapped;

	return generic_ioremap_prot(phys_addr, size, pgprot);
}
EXPORT_SYMBOL(ioremap_prot);

/*
 * Simple checks for non-translatable mappings.
 */
static inline int iomapping_nontranslatable(unsigned long offset)
{
#ifdef CONFIG_29BIT
	/*
	 * In 29-bit mode this includes the fixed P1/P2 areas, as well as
	 * parts of P3.
	 */
	if (PXSEG(offset) < P3SEG || offset >= P3_ADDR_MAX)
		return 1;
#endif

	return 0;
}

void iounmap(volatile void __iomem *addr)
{
	unsigned long vaddr = (unsigned long __force)addr;

	/*
	 * Nothing to do if there is no translatable mapping.
	 */
	if (iomapping_nontranslatable(vaddr))
		return;

	/*
	 * There's no VMA if it's from an early fixed mapping.
	 */
	if (iounmap_fixed((void __iomem *)addr) == 0)
		return;

	/*
	 * If the PMB handled it, there's nothing else to do.
	 */
	if (pmb_unmap((void __iomem *)addr) == 0)
		return;

	generic_iounmap(addr);
}
EXPORT_SYMBOL(iounmap);