Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k/math-emu: Remove unnecessary code
  m68k/math-emu: Remove commented out old code
  m68k: Kill warning in setup_arch() when compiling for Sun3
  m68k/atari: Prefix GPIO_{IN,OUT} with CODEC_
  sparc: iounmap() and *_free_coherent() - Use lookup_resource()
  m68k/atari: Reserve some ST-RAM early on for device buffer use
  m68k/amiga: Chip RAM - Use lookup_resource()
  resources: Add lookup_resource()
  sparc: _sparc_find_resource() should check for exact matches
  m68k/amiga: Chip RAM - Offset resource end by CHIP_PHYSADDR
  m68k/amiga: Chip RAM - Use resource_size() to fix off-by-one error
  m68k/amiga: Chip RAM - Change chipavail to an atomic_t
  m68k/amiga: Chip RAM - Always allocate from the start of memory
  m68k/amiga: Chip RAM - Convert from printk() to pr_*()
  m68k/amiga: Chip RAM - Use tabs for indentation

1 files changed, 21 insertions, 0 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index 3ff40178dce7..3b3cedc52592 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -553,6 +553,27 @@ int allocate_resource(struct resource *root, struct resource *new,
 
 EXPORT_SYMBOL(allocate_resource);
 
+/**
+ * lookup_resource - find an existing resource by a resource start address
+ * @root: root resource descriptor
+ * @start: resource start address
+ *
+ * Returns a pointer to the resource if found, NULL otherwise
+ */
+struct resource *lookup_resource(struct resource *root, resource_size_t start)
+{
+	struct resource *res;
+
+	read_lock(&resource_lock);
+	for (res = root->child; res; res = res->sibling) {
+		if (res->start == start)
+			break;
+	}
+	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())