[PATCH v3 32/32] lib: implement Devres ioremap_nopost() interface

Lorenzo Pieralisi
2017-04-11T12:30:44Z

The introduction of the ioremap_nopost() interface allows
kernel drivers to map memory through a dedicated kernel
interface providing non-posted writes semantics.

Introduce two new functions in the Devres kernel layer and Devres
documentation:

- devm_ioremap_nopost()
- devm_ioremap_nopost_resource()

so that drivers can make use of devm_* interface to map memory
regions requiring non-posted writes memory attributes.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Tejun Heo <tj@kernel.org>
---
Documentation/driver-model/devres.txt | 3 ++
include/linux/device.h | 2 +
include/linux/io.h | 2 +
lib/devres.c | 78 +++++++++++++++++++++++++++++++++++
4 files changed, 85 insertions(+)

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index bf34d5b..9991a66 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -294,7 +294,10 @@ IOMAP
devm_ioremap()
devm_ioremap_nocache()
devm_ioremap_wc()
+ devm_ioremap_nopost()
devm_ioremap_resource() : checks resource, requests memory region, ioremaps
+ devm_ioremap_nopost_resource() : do devm_ioremap_resource() with nopost
+ memory attributes
devm_iounmap()
pcim_iomap()
pcim_iomap_regions() : do request_region() and iomap() on multiple BARs
diff --git a/include/linux/device.h b/include/linux/device.h
index 9ef518a..1dce865 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -689,6 +689,8 @@ extern unsigned long devm_get_free_pages(struct device *dev,
extern void devm_free_pages(struct device *dev, unsigned long addr);

void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
+void __iomem *devm_ioremap_nopost_resource(struct device *dev,
+ struct resource *res);

/* allows to add/remove a custom action to devres stack */
int devm_add_action(struct device *dev, void (*action)(void *), void *data);
diff --git a/include/linux/io.h b/include/linux/io.h
index 82ef36e..e34d799 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -79,6 +79,8 @@ void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
resource_size_t size);
void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
resource_size_t size);
+void __iomem *devm_ioremap_nopost(struct device *dev, resource_size_t offset,
+ resource_size_t size);
void devm_iounmap(struct device *dev, void __iomem *addr);
int check_signature(const volatile void __iomem *io_addr,
const unsigned char *signature, int length);
diff --git a/lib/devres.c b/lib/devres.c
index 78eca71..d16bd76 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -100,6 +100,34 @@ void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
EXPORT_SYMBOL(devm_ioremap_wc);

/**
+ * devm_ioremap_nopost - Managed ioremap_nopost()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_nopost(). Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_nopost(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+ void __iomem **ptr, *addr;
+
+ ptr = devres_alloc(devm_ioremap_release, sizeof(*ptr), GFP_KERNEL);
+ if (!ptr)
+ return NULL;
+
+ addr = ioremap_nopost(offset, size);
+ if (addr) {
+ *ptr = addr;
+ devres_add(dev, ptr);
+ } else
+ devres_free(ptr);
+
+ return addr;
+}
+EXPORT_SYMBOL(devm_ioremap_nopost);
+
+/**
* devm_iounmap - Managed iounmap()
* @dev: Generic device to unmap for
* @addr: Address to unmap
@@ -163,6 +191,56 @@ void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
}
EXPORT_SYMBOL(devm_ioremap_resource);

+/**
+ * devm_ioremap_nopost_resource() - devm_ioremap_resource() nopost version
+ * @dev: generic device to handle the resource for
+ * @res: resource to be handled
+ *
+ * Checks that a resource is a valid memory region, requests the memory
+ * region and ioremaps it with ioremap_nopost() interface.
+ * All operations are managed and will be undone on driver detach.
+ *
+ * Returns a pointer to the remapped memory or an ERR_PTR() encoded error code
+ * on failure. Usage example:
+ *
+ * res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ * base = devm_ioremap_nopost_resource(&pdev->dev, res);
+ * if (IS_ERR(base))
+ * return PTR_ERR(base);
+ */
+void __iomem *devm_ioremap_nopost_resource(struct device *dev,
+ struct resource *res)
+{
+ resource_size_t size;
+ const char *name;
+ void __iomem *dest_ptr;
+
+ BUG_ON(!dev);
+
+ if (!res || resource_type(res) != IORESOURCE_MEM) {
+ dev_err(dev, "invalid resource\n");
+ return IOMEM_ERR_PTR(-EINVAL);
+ }
+
+ size = resource_size(res);
+ name = res->name ?: dev_name(dev);
+
+ if (!devm_request_mem_region(dev, res->start, size, name)) {
+ dev_err(dev, "can't request region for resource %pR\n", res);
+ return IOMEM_ERR_PTR(-EBUSY);
+ }
+
+ dest_ptr = devm_ioremap_nopost(dev, res->start, size);
+ if (!dest_ptr) {
+ dev_err(dev, "ioremap failed for resource %pR\n", res);
+ devm_release_mem_region(dev, res->start, size);
+ dest_ptr = IOMEM_ERR_PTR(-ENOMEM);
+ }
+
+ return dest_ptr;
+}
+EXPORT_SYMBOL(devm_ioremap_nopost_resource);
+
#ifdef CONFIG_HAS_IOPORT_MAP
/*
* Generic iomap devres
--
2.10.0