1 files changed, 160 insertions, 0 deletions

diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
index 8244f013f210..fcb7807ea8b7 100644
--- a/drivers/acpi/resource.c
+++ b/drivers/acpi/resource.c
@@ -26,6 +26,7 @@
 #include <linux/device.h>
 #include <linux/export.h>
 #include <linux/ioport.h>
+#include <linux/list.h>
 #include <linux/slab.h>
 
 #ifdef CONFIG_X86
@@ -621,3 +622,162 @@ int acpi_dev_filter_resource_type(struct acpi_resource *ares,
         return (type & types) ? 0 : 1;
 }
 EXPORT_SYMBOL_GPL(acpi_dev_filter_resource_type);
+
+struct reserved_region {
+        struct list_head node;
+        u64 start;
+        u64 end;
+};
+
+static LIST_HEAD(reserved_io_regions);
+static LIST_HEAD(reserved_mem_regions);
+
+static int request_range(u64 start, u64 end, u8 space_id, unsigned long flags,
+                         char *desc)
+{
+        unsigned int length = end - start + 1;
+        struct resource *res;
+
+        res = space_id == ACPI_ADR_SPACE_SYSTEM_IO ?
+                request_region(start, length, desc) :
+                request_mem_region(start, length, desc);
+        if (!res)
+                return -EIO;
+
+        res->flags &= ~flags;
+        return 0;
+}
+
+static int add_region_before(u64 start, u64 end, u8 space_id,
+                             unsigned long flags, char *desc,
+                             struct list_head *head)
+{
+        struct reserved_region *reg;
+        int error;
+
+        reg = kmalloc(sizeof(*reg), GFP_KERNEL);
+        if (!reg)
+                return -ENOMEM;
+
+        error = request_range(start, end, space_id, flags, desc);
+        if (error)
+                return error;
+
+        reg->start = start;
+        reg->end = end;
+        list_add_tail(&reg->node, head);
+        return 0;
+}
+
+/**
+ * acpi_reserve_region - Reserve an I/O or memory region as a system resource.
+ * @start: Starting address of the region.
+ * @length: Length of the region.
+ * @space_id: Identifier of address space to reserve the region from.
+ * @flags: Resource flags to clear for the region after requesting it.
+ * @desc: Region description (for messages).
+ *
+ * Reserve an I/O or memory region as a system resource to prevent others from
+ * using it.  If the new region overlaps with one of the regions (in the given
+ * address space) already reserved by this routine, only the non-overlapping
+ * parts of it will be reserved.
+ *
+ * Returned is either 0 (success) or a negative error code indicating a resource
+ * reservation problem.  It is the code of the first encountered error, but the
+ * routine doesn't abort until it has attempted to request all of the parts of
+ * the new region that don't overlap with other regions reserved previously.
+ *
+ * The resources requested by this routine are never released.
+ */
+int acpi_reserve_region(u64 start, unsigned int length, u8 space_id,
+                        unsigned long flags, char *desc)
+{
+        struct list_head *regions;
+        struct reserved_region *reg;
+        u64 end = start + length - 1;
+        int ret = 0, error = 0;
+
+        if (space_id == ACPI_ADR_SPACE_SYSTEM_IO)
+                regions = &reserved_io_regions;
+        else if (space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+                regions = &reserved_mem_regions;
+        else
+                return -EINVAL;
+
+        if (list_empty(regions))
+                return add_region_before(start, end, space_id, flags, desc, regions);
+
+        list_for_each_entry(reg, regions, node)
+                if (reg->start == end + 1) {
+                        /* The new region can be prepended to this one. */
+                        ret = request_range(start, end, space_id, flags, desc);
+                        if (!ret)
+                                reg->start = start;
+
+                        return ret;
+                } else if (reg->start > end) {
+                        /* No overlap.  Add the new region here and get out. */
+                        return add_region_before(start, end, space_id, flags,
+                                                 desc, &reg->node);
+                } else if (reg->end == start - 1) {
+                        goto combine;
+                } else if (reg->end >= start) {
+                        goto overlap;
+                }
+
+        /* The new region goes after the last existing one. */
+        return add_region_before(start, end, space_id, flags, desc, regions);
+
+ overlap:
+        /*
+         * The new region overlaps an existing one.
+         *
+         * The head part of the new region immediately preceding the existing
+         * overlapping one can be combined with it right away.
+         */
+        if (reg->start > start) {
+                error = request_range(start, reg->start - 1, space_id, flags, desc);
+                if (error)
+                        ret = error;
+                else
+                        reg->start = start;
+        }
+
+ combine:
+        /*
+         * The new region is adjacent to an existing one.  If it extends beyond
+         * that region all the way to the next one, it is possible to combine
+         * all three of them.
+         */
+        while (reg->end < end) {
+                struct reserved_region *next = NULL;
+                u64 a = reg->end + 1, b = end;
+
+                if (!list_is_last(&reg->node, regions)) {
+                        next = list_next_entry(reg, node);
+                        if (next->start <= end)
+                                b = next->start - 1;
+                }
+                error = request_range(a, b, space_id, flags, desc);
+                if (!error) {
+                        if (next && next->start == b + 1) {
+                                reg->end = next->end;
+                                list_del(&next->node);
+                                kfree(next);
+                        } else {
+                                reg->end = end;
+                                break;
+                        }
+                } else if (next) {
+                        if (!ret)
+                                ret = error;
+
+                        reg = next;
+                } else {
+                        break;
+                }
+        }
+
+        return ret ? ret : error;
+}
+EXPORT_SYMBOL_GPL(acpi_reserve_region);