[PATCH v2 1/2] platform_device: add devres function region-reqs

[Philipp Stanner <pstanner@redhat.com>]

Some drivers want to use (request) a region exclusively but nevertheless
create several mappings within that region.

Currently, there is no managed devres function to request a region
without mapping it.

Add the function devm_platform_get_resource().

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 drivers/base/platform.c         | 38 +++++++++++++++++++++++++++++++++
 include/linux/platform_device.h |  3 +++
 2 files changed, 41 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 10c577963418..7b29e6da31ae 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -82,6 +82,44 @@ struct resource *platform_get_mem_or_io(struct platform_device *dev,
 }
 EXPORT_SYMBOL_GPL(platform_get_mem_or_io);
 
+/**
+ * devm_platform_get_and_request_resource - get and request a resource
+ *
+ * @pdev: the platform device to get the resource from
+ * @type: resource type (either IORESOURCE_MEM or IORESOURCE_IO)
+ * @num: resource index
+ * @name: name to be associated with the request
+ *
+ * Return: a pointer to the resource on success, an ERR_PTR on failure.
+ *
+ * Gets a resource and requests it. Use this instead of
+ * devm_platform_ioremap_resource() only if you have to create several single
+ * mappings with devm_ioremap().
+ */
+struct resource *devm_platform_get_and_request_resource(
+		struct platform_device *pdev, unsigned int type,
+		unsigned int num, const char *name)
+{
+	struct resource *res;
+
+	res = platform_get_resource(pdev, type, num);
+	if (!res)
+		return ERR_PTR(-EINVAL);
+
+	if (type & IORESOURCE_MEM)
+		res = devm_request_mem_region(&pdev->dev, res->start, res->end, name);
+	else if (type & IORESOURCE_IO)
+		res = devm_request_region(&pdev->dev, res->start, res->end, name);
+	else
+		return ERR_PTR(-EINVAL);
+
+	if (!res)
+		return ERR_PTR(-EBUSY);
+
+	return res;
+}
+EXPORT_SYMBOL_GPL(devm_platform_get_and_request_resource);
+
 #ifdef CONFIG_HAS_IOMEM
 /**
  * devm_platform_get_and_ioremap_resource - call devm_ioremap_resource() for a
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 7a41c72c1959..44e4ba930d5f 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -59,6 +59,9 @@ extern struct resource *platform_get_resource(struct platform_device *,
 					      unsigned int, unsigned int);
 extern struct resource *platform_get_mem_or_io(struct platform_device *,
 					       unsigned int);
+extern struct resource *devm_platform_get_and_request_resource(
+		struct platform_device *pdev, unsigned int type,
+		unsigned int num, const char *name);
 
 extern struct device *
 platform_find_device_by_driver(struct device *start,
-- 
2.43.0