[PATCH] devres: Add devm_of_iomap()

[PATCH] devres: Add devm_of_iomap()

[Benjamin Herrenschmidt]

There are still quite a few cases where a device might want
to get to a different node of the device-tree, obtain the
resources and map them.

This is generally open coded in drivers which is quite error prone

We have of_iomap() and of_io_request_and_map() but they both
have shortcomings, such as not returning the size of the
resource found (which can be useful) and not being "managed".

This adds a devm_of_iomap() that provides all of these and
should probably replace uses of the above in most drivers.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 include/linux/device.h |  4 ++++
 lib/devres.c           | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/linux/device.h b/include/linux/device.h
index beabdbc08420..1529775ecb36 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -686,6 +686,10 @@ 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_of_iomap(struct device *dev,
+			    struct device_node *node, int index,
+			    resource_size_t *size);
+
 /* allows to add/remove a custom action to devres stack */
 int devm_add_action(struct device *dev, void (*action)(void *), void *data);
 void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
diff --git a/lib/devres.c b/lib/devres.c
index 78eca713b1d9..e320f80c1c4e 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -3,6 +3,7 @@
 #include <linux/io.h>
 #include <linux/gfp.h>
 #include <linux/export.h>
+#include <linux/of_address.h>
 
 void devm_ioremap_release(struct device *dev, void *res)
 {
@@ -163,6 +164,41 @@ void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
 }
 EXPORT_SYMBOL(devm_ioremap_resource);
 
+/*
+ * devm_of_iomap - Requests a resource and maps the memory mapped IO
+ *		   for a given device_node managed by a given device
+ *
+ * Checks that a resource is a valid memory region, requests the memory
+ * region and ioremaps it. All operations are managed and will be undone
+ * on driver detach of the device.
+ *
+ * This is to be used when a device requests/maps resources described
+ * by other device tree nodes (children or otherwise).
+ *
+ * @dev:	The device "managing" the resource
+ * @node:       The device-tree node where the resource resides
+ * @index:	index of the MMIO range in the "reg" property
+ * @size:	Returns the size of the resource (pass NULL if not needed)
+ * Returns a pointer to the requested and mapped memory or an ERR_PTR() encoded
+ * error code on failure. Usage example:
+ *
+ *	base = devm_of_iomap(&pdev->dev, node, 0, NULL);
+ *	if (IS_ERR(base))
+ *		return PTR_ERR(base);
+ */
+void __iomem *devm_of_iomap(struct device *dev, struct device_node *node, int index,
+			    resource_size_t *size)
+{
+	struct resource res;
+
+	if (of_address_to_resource(node, index, &res))
+		return IOMEM_ERR_PTR(-EINVAL);
+	if (size)
+		*size = resource_size(&res);
+	return devm_ioremap_resource(dev, &res);
+}
+EXPORT_SYMBOL(devm_of_iomap);
+
 #ifdef CONFIG_HAS_IOPORT_MAP
 /*
  * Generic iomap devres

Re: [PATCH] devres: Add devm_of_iomap()

[Benjamin Herrenschmidt]

On Thu, 2018-06-14 at 13:31 +1000, Benjamin Herrenschmidt wrote:
> There are still quite a few cases where a device might want
> to get to a different node of the device-tree, obtain the
> resources and map them.
> 
> This is generally open coded in drivers which is quite error prone
> 
> We have of_iomap() and of_io_request_and_map() but they both
> have shortcomings, such as not returning the size of the
> resource found (which can be useful) and not being "managed".
> 
> This adds a devm_of_iomap() that provides all of these and
> should probably replace uses of the above in most drivers.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---

Greg, which tree should this go through ? Rob, ack pls ? :-)

I have dependencies on this coming up... I can put it in the FSI tree
if you want, it will be part of my next pull request.

Cheers,
Ben.


>  include/linux/device.h |  4 ++++
>  lib/devres.c           | 36 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/include/linux/device.h b/include/linux/device.h
> index beabdbc08420..1529775ecb36 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -686,6 +686,10 @@ 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_of_iomap(struct device *dev,
> +			    struct device_node *node, int index,
> +			    resource_size_t *size);
> +
>  /* allows to add/remove a custom action to devres stack */
>  int devm_add_action(struct device *dev, void (*action)(void *), void *data);
>  void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
> diff --git a/lib/devres.c b/lib/devres.c
> index 78eca713b1d9..e320f80c1c4e 100644
> --- a/lib/devres.c
> +++ b/lib/devres.c
> @@ -3,6 +3,7 @@
>  #include <linux/io.h>
>  #include <linux/gfp.h>
>  #include <linux/export.h>
> +#include <linux/of_address.h>
>  
>  void devm_ioremap_release(struct device *dev, void *res)
>  {
> @@ -163,6 +164,41 @@ void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
>  }
>  EXPORT_SYMBOL(devm_ioremap_resource);
>  
> +/*
> + * devm_of_iomap - Requests a resource and maps the memory mapped IO
> + *		   for a given device_node managed by a given device
> + *
> + * Checks that a resource is a valid memory region, requests the memory
> + * region and ioremaps it. All operations are managed and will be undone
> + * on driver detach of the device.
> + *
> + * This is to be used when a device requests/maps resources described
> + * by other device tree nodes (children or otherwise).
> + *
> + * @dev:	The device "managing" the resource
> + * @node:       The device-tree node where the resource resides
> + * @index:	index of the MMIO range in the "reg" property
> + * @size:	Returns the size of the resource (pass NULL if not needed)
> + * Returns a pointer to the requested and mapped memory or an ERR_PTR() encoded
> + * error code on failure. Usage example:
> + *
> + *	base = devm_of_iomap(&pdev->dev, node, 0, NULL);
> + *	if (IS_ERR(base))
> + *		return PTR_ERR(base);
> + */
> +void __iomem *devm_of_iomap(struct device *dev, struct device_node *node, int index,
> +			    resource_size_t *size)
> +{
> +	struct resource res;
> +
> +	if (of_address_to_resource(node, index, &res))
> +		return IOMEM_ERR_PTR(-EINVAL);
> +	if (size)
> +		*size = resource_size(&res);
> +	return devm_ioremap_resource(dev, &res);
> +}
> +EXPORT_SYMBOL(devm_of_iomap);
> +
>  #ifdef CONFIG_HAS_IOPORT_MAP
>  /*
>   * Generic iomap devres

Re: [PATCH] devres: Add devm_of_iomap()

[Greg Kroah-Hartman]

On Fri, Jun 22, 2018 at 02:13:15PM +1000, Benjamin Herrenschmidt wrote:
> On Thu, 2018-06-14 at 13:31 +1000, Benjamin Herrenschmidt wrote:
> > There are still quite a few cases where a device might want
> > to get to a different node of the device-tree, obtain the
> > resources and map them.
> > 
> > This is generally open coded in drivers which is quite error prone
> > 
> > We have of_iomap() and of_io_request_and_map() but they both
> > have shortcomings, such as not returning the size of the
> > resource found (which can be useful) and not being "managed".
> > 
> > This adds a devm_of_iomap() that provides all of these and
> > should probably replace uses of the above in most drivers.
> > 
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > ---
> 
> Greg, which tree should this go through ? Rob, ack pls ? :-)
> 
> I have dependencies on this coming up... I can put it in the FSI tree
> if you want, it will be part of my next pull request.

Usually new devres patches just go through whatever tree needs it, so no
objection from me for you to take these in your next pull request.

thanks,

greg k-h