HPET: fix ACPI memory range length handling

ACPI address space descriptors contain _MIN, _MAX, and _LEN.  _MIN and _MAX
are the bounds within which the region can be moved (this is clarified in
Table 6-38 of the ACPI 3.0 spec).  We should use _LEN to determine the size
of the region, not _MAX - _MIN + 1.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index ef140ebde117..07473cd84121 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -925,11 +925,8 @@ static acpi_status hpet_resources(struct acpi_resource *res, void *data)
         status = acpi_resource_to_address64(res, &addr);
 
         if (ACPI_SUCCESS(status)) {
-                unsigned long size;
-
-                size = addr.maximum - addr.minimum + 1;
                 hdp->hd_phys_address = addr.minimum;
-                hdp->hd_address = ioremap(addr.minimum, size);
+                hdp->hd_address = ioremap(addr.minimum, addr.address_length);
 
                 if (hpet_is_known(hdp)) {
                         printk(KERN_DEBUG "%s: 0x%lx is busy\n",