1 files changed, 72 insertions, 0 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 7ca41bf023c9..8df9abfa947b 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -45,6 +45,8 @@
 #include <linux/uaccess.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 
+#include "acpica/accommon.h"
+#include "acpica/acnamesp.h"
 #include "internal.h"
 
 #define _COMPONENT              ACPI_OS_SERVICES
@@ -1490,6 +1492,76 @@ int acpi_check_region(resource_size_t start, resource_size_t n,
 }
 EXPORT_SYMBOL(acpi_check_region);
 
+static acpi_status acpi_deactivate_mem_region(acpi_handle handle, u32 level,
+                                              void *_res, void **return_value)
+{
+        struct acpi_mem_space_context **mem_ctx;
+        union acpi_operand_object *handler_obj;
+        union acpi_operand_object *region_obj2;
+        union acpi_operand_object *region_obj;
+        struct resource *res = _res;
+        acpi_status status;
+
+        region_obj = acpi_ns_get_attached_object(handle);
+        if (!region_obj)
+                return AE_OK;
+
+        handler_obj = region_obj->region.handler;
+        if (!handler_obj)
+                return AE_OK;
+
+        if (region_obj->region.space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
+                return AE_OK;
+
+        if (!(region_obj->region.flags & AOPOBJ_SETUP_COMPLETE))
+                return AE_OK;
+
+        region_obj2 = acpi_ns_get_secondary_object(region_obj);
+        if (!region_obj2)
+                return AE_OK;
+
+        mem_ctx = (void *)&region_obj2->extra.region_context;
+
+        if (!(mem_ctx[0]->address >= res->start &&
+              mem_ctx[0]->address < res->end))
+                return AE_OK;
+
+        status = handler_obj->address_space.setup(region_obj,
+                                                  ACPI_REGION_DEACTIVATE,
+                                                  NULL, (void **)mem_ctx);
+        if (ACPI_SUCCESS(status))
+                region_obj->region.flags &= ~(AOPOBJ_SETUP_COMPLETE);
+
+        return status;
+}
+
+/**
+ * acpi_release_memory - Release any mappings done to a memory region
+ * @handle: Handle to namespace node
+ * @res: Memory resource
+ * @level: A level that terminates the search
+ *
+ * Walks through @handle and unmaps all SystemMemory Operation Regions that
+ * overlap with @res and that have already been activated (mapped).
+ *
+ * This is a helper that allows drivers to place special requirements on memory
+ * region that may overlap with operation regions, primarily allowing them to
+ * safely map the region as non-cached memory.
+ *
+ * The unmapped Operation Regions will be automatically remapped next time they
+ * are called, so the drivers do not need to do anything else.
+ */
+acpi_status acpi_release_memory(acpi_handle handle, struct resource *res,
+                                u32 level)
+{
+        if (!(res->flags & IORESOURCE_MEM))
+                return AE_TYPE;
+
+        return acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
+                                   acpi_deactivate_mem_region, NULL, res, NULL);
+}
+EXPORT_SYMBOL_GPL(acpi_release_memory);
+
 /*
  * Let drivers know whether the resource checks are effective
  */