[PATCH v2 1/6] resource: Add device-managed request/release_resource()

Thierry Reding
2014-08-26T14:57:55Z

Provide device-managed implementations of the request_resource() and
release_resource() functions. Upon failure to request a resource, the
new devm_request_resource() function will output an error message for
consistent error reporting.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v2:
- use more natural flow for error handling
- don't needlessly check for NULL pointers

Documentation/driver-model/devres.txt | 2 +
include/linux/ioport.h | 5 +++
kernel/resource.c | 70 +++++++++++++++++++++++++++++++++++
3 files changed, 77 insertions(+)

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index d14710b04439..befc3fe12ba6 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -264,8 +264,10 @@ IIO
IO region
devm_release_mem_region()
devm_release_region()
+ devm_release_resource()
devm_request_mem_region()
devm_request_region()
+ devm_request_resource()

IOMAP
devm_ioport_map()
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 142ec544167c..2c5250222278 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -215,6 +215,11 @@ static inline int __deprecated check_region(resource_size_t s,

/* Wrappers for managed devices */
struct device;
+
+extern int devm_request_resource(struct device *dev, struct resource *root,
+ struct resource *new);
+extern void devm_release_resource(struct device *dev, struct resource *new);
+
#define devm_request_region(dev,start,n,name) \
__devm_request_region(dev, &ioport_resource, (start), (n), (name))
#define devm_request_mem_region(dev,start,n,name) \
diff --git a/kernel/resource.c b/kernel/resource.c
index 60c5a3856ab7..46322019ab7d 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1245,6 +1245,76 @@ int release_mem_region_adjustable(struct resource *parent,
/*
* Managed region resource
*/
+static void devm_resource_release(struct device *dev, void *ptr)
+{
+ struct resource **r = ptr;
+
+ release_resource(*r);
+}
+
+/**
+ * devm_request_resource() - request and reserve an I/O or memory resource
+ * @dev: device for which to request the resource
+ * @root: root of the resource tree from which to request the resource
+ * @new: descriptor of the resource to request
+ *
+ * This is a device-managed version of request_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 driver.
+ * If for some reason the resource needs to be released explicitly, because
+ * of ordering issues for example, drivers must call devm_release_resource()
+ * rather than the regular release_resource().
+ *
+ * When a conflict is detected between any existing resources and the newly
+ * requested resource, an error message will be printed.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int devm_request_resource(struct device *dev, struct resource *root,
+ struct resource *new)
+{
+ struct resource *conflict, **ptr;
+
+ ptr = devres_alloc(devm_resource_release, sizeof(*ptr), GFP_KERNEL);
+ if (!ptr)
+ return -ENOMEM;
+
+ *ptr = new;
+
+ conflict = request_resource_conflict(root, new);
+ if (conflict) {
+ dev_err(dev, "resource collision: %pR conflicts with %s %pR\n",
+ new, conflict->name, conflict);
+ devres_free(ptr);
+ return -EBUSY;
+ }
+
+ devres_add(dev, ptr);
+ return 0;
+}
+EXPORT_SYMBOL(devm_request_resource);
+
+static int devm_resource_match(struct device *dev, void *res, void *data)
+{
+ struct resource **ptr = res;
+
+ return *ptr == data;
+}
+
+/**
+ * devm_release_resource() - release a previously requested resource
+ * @dev: device for which to release the resource
+ * @new: descriptor of the resource to release
+ *
+ * Releases a resource previously requested using devm_request_resource().
+ */
+void devm_release_resource(struct device *dev, struct resource *new)
+{
+ WARN_ON(devres_release(dev, devm_resource_release, devm_resource_match,
+ new));
+}
+EXPORT_SYMBOL(devm_release_resource);
+
struct region_devres {
struct resource *parent;
resource_size_t start;
--
2.0.4