[PATCH v2-UPDATE2 3/4] resource: Add device-managed insert/remove_resource()

[Toshi Kani]

insert_resource() and remove_resouce() are called by producers
of resources, such as FW modules and bus drivers.  These modules
may be implemented as loadable modules.

Add device-managed implementaions of insert_resource() and
remove_resouce() functions.

Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
---
v2-UPDATE2:
 - Update per Ingo's review comments; use ret, use WARN_ON_ONCE().
v2-UPDATE:
 - Rename a helper remove func to __devm_remove_resource(). (Dan Williams)
---
 include/linux/ioport.h |    5 +++
 kernel/resource.c      |   72 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 8017b8b..3580038 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -259,6 +259,11 @@ extern struct resource * __devm_request_region(struct device *dev,
 
 extern void __devm_release_region(struct device *dev, struct resource *parent,
 				  resource_size_t start, resource_size_t n);
+
+extern int devm_insert_resource(struct device *dev, struct resource *root,
+				 struct resource *new);
+extern void devm_remove_resource(struct device *dev, struct resource *old);
+
 extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);
 extern int iomem_is_exclusive(u64 addr);
 
diff --git a/kernel/resource.c b/kernel/resource.c
index effb6ee..86fdd28 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1449,6 +1449,78 @@ void __devm_release_region(struct device *dev, struct resource *parent,
 EXPORT_SYMBOL(__devm_release_region);
 
 /*
+ * Helper remove function for devm_insert_resource() and devm_remove_resource()
+ */
+static void __devm_remove_resource(struct device *dev, void *ptr)
+{
+	struct resource **r = ptr;
+
+	remove_resource(*r);
+}
+
+/**
+ * devm_insert_resource() - insert an I/O or memory resource
+ * @dev: device for which to produce the resource
+ * @root: root of the resource tree
+ * @new: descriptor of the new resource
+ *
+ * This is a device-managed version of insert_resource(). There is usually
+ * no need to release resources requested by this function explicitly, since
+ * that will be taken care of when the device is unbound from its bus driver.
+ * If for some reason the resource needs to be released explicitly, because
+ * of ordering issues for example, bus drivers must call devm_remove_resource()
+ * rather than the regular remove_resource().
+ *
+ * devm_insert_resource() is intended for producers of resources, such as
+ * FW modules and bus drivers.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int devm_insert_resource(struct device *dev, struct resource *root,
+			  struct resource *new)
+{
+	struct resource **ptr;
+	int ret;
+
+	ptr = devres_alloc(__devm_remove_resource, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	*ptr = new;
+
+	ret = insert_resource(root, new);
+	if (ret) {
+		dev_err(dev, "unable to insert resource: %pR (%d)\n", new, ret);
+		devres_free(ptr);
+		return ret;
+	}
+
+	devres_add(dev, ptr);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_insert_resource);
+
+/**
+ * devm_remove_resource() - remove a previously inserted resource
+ * @dev: device for which to remove the resource
+ * @old: descriptor of the resource
+ *
+ * Remove a resource previously inserted using devm_insert_resource().
+ *
+ * devm_remove_resource() is intended for producers of resources, such as
+ * FW modules and bus drivers.
+ */
+void devm_remove_resource(struct device *dev, struct resource *old)
+{
+	int ret;
+
+	ret = devres_release(dev, __devm_remove_resource,
+			     devm_resource_match, old);
+	WARN_ON_ONCE(ret);
+}
+EXPORT_SYMBOL_GPL(devm_remove_resource);
+
+/*
  * Called from init/main.c to reserve IO ports.
  */
 #define MAXRESERVE 4