linux/arch/ia64/mm/ioremap.c
Bjorn Helgaas 9b50ffb0c0 [IA64] make ioremap avoid unsupported attributes
Example memory map (from HP sx1000 with VGA enabled):
    0x00000 - 0x9FFFF supports only WB (cacheable) access
    0xA0000 - 0xBFFFF supports only UC (uncacheable) access
    0xC0000 - 0xFFFFF supports only WB (cacheable) access

pci_read_rom() indirectly uses ioremap(0xC0000) to read the shadow VGA option
ROM.  ioremap() used to default to a 16MB or 64MB UC kernel identity mapping,
which would cause an MCA when reading 0xC0000 since only WB is supported there.

X uses reads the option ROM to initialize devices.  A smaller test case is:
  # echo 1 > /sys/bus/pci/devices/0000:aa:03.0/rom
  # cp /sys/bus/pci/devices/0000:aa:03.0/rom x

To avoid this, we can use the same ioremap_page_range() strategy that most
architectures use for all ioremaps.  These page table mappings come out of the
vmalloc area.  On ia64, these are in region 5 (0xA... addresses) and typically
use 16KB or 64KB mappings instead of 16MB or 64MB mappings.  The smaller
mappings give more flexibility to use the correct attributes.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2007-03-30 09:37:41 -07:00

111 lines
2.8 KiB
C

/*
* (c) Copyright 2006, 2007 Hewlett-Packard Development Company, L.P.
* Bjorn Helgaas <bjorn.helgaas@hp.com>
*
* 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.
*/
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/efi.h>
#include <linux/io.h>
#include <linux/vmalloc.h>
#include <asm/io.h>
#include <asm/meminit.h>
static inline void __iomem *
__ioremap (unsigned long phys_addr)
{
return (void __iomem *) (__IA64_UNCACHED_OFFSET | phys_addr);
}
void __iomem *
ioremap (unsigned long phys_addr, unsigned long size)
{
void __iomem *addr;
struct vm_struct *area;
unsigned long offset;
pgprot_t prot;
u64 attr;
unsigned long gran_base, gran_size;
unsigned long page_base;
/*
* For things in kern_memmap, we must use the same attribute
* as the rest of the kernel. For more details, see
* Documentation/ia64/aliasing.txt.
*/
attr = kern_mem_attribute(phys_addr, size);
if (attr & EFI_MEMORY_WB)
return (void __iomem *) phys_to_virt(phys_addr);
else if (attr & EFI_MEMORY_UC)
return __ioremap(phys_addr);
/*
* Some chipsets don't support UC access to memory. If
* WB is supported for the whole granule, we prefer that.
*/
gran_base = GRANULEROUNDDOWN(phys_addr);
gran_size = GRANULEROUNDUP(phys_addr + size) - gran_base;
if (efi_mem_attribute(gran_base, gran_size) & EFI_MEMORY_WB)
return (void __iomem *) phys_to_virt(phys_addr);
/*
* WB is not supported for the whole granule, so we can't use
* the region 7 identity mapping. If we can safely cover the
* area with kernel page table mappings, we can use those
* instead.
*/
page_base = phys_addr & PAGE_MASK;
size = PAGE_ALIGN(phys_addr + size) - page_base;
if (efi_mem_attribute(page_base, size) & EFI_MEMORY_WB) {
prot = PAGE_KERNEL;
/*
* Mappings have to be page-aligned
*/
offset = phys_addr & ~PAGE_MASK;
phys_addr &= PAGE_MASK;
/*
* Ok, go for it..
*/
area = get_vm_area(size, VM_IOREMAP);
if (!area)
return NULL;
area->phys_addr = phys_addr;
addr = (void __iomem *) area->addr;
if (ioremap_page_range((unsigned long) addr,
(unsigned long) addr + size, phys_addr, prot)) {
vunmap((void __force *) addr);
return NULL;
}
return (void __iomem *) (offset + (char __iomem *)addr);
}
return __ioremap(phys_addr);
}
EXPORT_SYMBOL(ioremap);
void __iomem *
ioremap_nocache (unsigned long phys_addr, unsigned long size)
{
if (kern_mem_attribute(phys_addr, size) & EFI_MEMORY_WB)
return NULL;
return __ioremap(phys_addr);
}
EXPORT_SYMBOL(ioremap_nocache);
void
iounmap (volatile void __iomem *addr)
{
if (REGION_NUMBER(addr) == RGN_GATE)
vunmap((void *) ((unsigned long) addr & PAGE_MASK));
}
EXPORT_SYMBOL(iounmap);