This is useful for drivers to find a resource inserted by, for example,
an early PCI quirk.

v2: We need to recurse through the resource tree as the named region we
are looking for may be a grandchild of the root node.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Jesse Barnes <jbar...@virtuousgeek.org>
---
 include/linux/ioport.h |  2 ++
 kernel/resource.c      | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 89b7c24..acad72f 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -158,6 +158,8 @@ extern int allocate_resource(struct resource *root, struct 
resource *new,
                                                       resource_size_t),
                             void *alignf_data);
 struct resource *lookup_resource(struct resource *root, resource_size_t start);
+struct resource *lookup_resource_by_name(struct resource *root,
+                                        const char *name);
 int adjust_resource(struct resource *res, resource_size_t start,
                    resource_size_t size);
 resource_size_t resource_alignment(struct resource *res);
diff --git a/kernel/resource.c b/kernel/resource.c
index 3f285dc..c6dd827 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -624,6 +624,36 @@ struct resource *lookup_resource(struct resource *root, 
resource_size_t start)
        return res;
 }
 
+static struct resource *__lookup_resource_by_name(struct resource *res,
+                                                 const char *name)
+{
+       while (res) {
+               struct resource *child;
+
+               if (strcmp(res->name, name) == 0)
+                       return res;
+
+               child = __lookup_resource_by_name(res->child, name);
+               if (child)
+                       return child;
+
+               res = res->sibling;
+       }
+
+       return NULL;
+}
+
+struct resource *lookup_resource_by_name(struct resource *root, const char 
*name)
+{
+       struct resource *res;
+
+       read_lock(&resource_lock);
+       res = __lookup_resource_by_name(root->child, name);
+       read_unlock(&resource_lock);
+
+       return res;
+}
+
 /*
  * Insert a resource into the resource tree. If successful, return NULL,
  * otherwise return the conflicting resource (compare to __request_resource())
-- 
1.8.3.2

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