ACPI: Add interfaces for ioremapping/iounmapping ACPI registers

Add remapping and unmapping interfaces for ACPI registers that are
backed by memory mapped I/O (MMIO).  These interfaces, along with
the MMIO remapping list, enable accesses of such registers from within
interrupt context.

ACPI Generic Address Structure (GAS) reference (ACPI's fixed/generic
hardware registers use the GAS format):
  ACPI Specification, Revision 4.0, Section 5.2.3.1, "Generic Address
  Structure".

Signed-off-by: Myron Stowe <myron.stowe@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index bd72129e35f2..fc6c5d21c3eb 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -372,6 +372,44 @@ void __init early_acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
                 __acpi_unmap_table(virt, size);
 }
 
+int acpi_os_map_generic_address(struct acpi_generic_address *addr)
+{
+        void __iomem *virt;
+
+        if (addr->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
+                return 0;
+
+        if (!addr->address || !addr->bit_width)
+                return -EINVAL;
+
+        virt = acpi_os_map_memory(addr->address, addr->bit_width / 8);
+        if (!virt)
+                return -EIO;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_os_map_generic_address);
+
+void acpi_os_unmap_generic_address(struct acpi_generic_address *addr)
+{
+        void __iomem *virt;
+        unsigned long flags;
+        acpi_size size = addr->bit_width / 8;
+
+        if (addr->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
+                return;
+
+        if (!addr->address || !addr->bit_width)
+                return;
+
+        spin_lock_irqsave(&acpi_ioremap_lock, flags);
+        virt = acpi_map_vaddr_lookup(addr->address, size);
+        spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+
+        acpi_os_unmap_memory(virt, size);
+}
+EXPORT_SYMBOL_GPL(acpi_os_unmap_generic_address);
+
 #ifdef ACPI_FUTURE_USAGE
 acpi_status
 acpi_os_get_physical_address(void *virt, acpi_physical_address * phys)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index c227757feb06..7774e6d8fddd 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -308,6 +308,9 @@ extern acpi_status acpi_pci_osc_control_set(acpi_handle handle,
                                              u32 *mask, u32 req);
 extern void acpi_early_init(void);
 
+int acpi_os_map_generic_address(struct acpi_generic_address *addr);
+void acpi_os_unmap_generic_address(struct acpi_generic_address *addr);
+
 #else   /* !CONFIG_ACPI */
 
 #define acpi_disabled 1