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lib: devres: add convenience function to remap a resource

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Almost every platform_driver does the three steps get_resource,
request_mem_region, ioremap. This does not only lead to a lot of code
duplication, but also a huge number of similar error strings and
inconsistent error codes on failure. So, introduce a helper function
which simplifies remapping a resource and make it hard to do something
wrong and add documentation for it.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Wolfram Sang 2011-10-25 15:16:47 +02:00 committed by Greg Kroah-Hartman
parent 571806a9f7
commit 72f8c0bfa0
3 changed files with 55 additions and 0 deletions
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1
Documentation/driver-model/devres.txt
View File

@ -262,6 +262,7 @@ IOMAP
devm_ioremap()
devm_ioremap_nocache()
devm_iounmap()
devm_request_and_ioremap() : checks resource, requests region, ioremaps
pcim_iomap()
pcim_iounmap()
pcim_iomap_table() : array of mapped addresses indexed by BAR

3
include/linux/device.h
View File

@ -490,6 +490,9 @@ extern int devres_release_group(struct device *dev, void *id);
extern void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp);
extern void devm_kfree(struct device *dev, void *p);
void __iomem *devm_request_and_ioremap(struct device *dev,
struct resource *res);
struct device_dma_parameters {
/*
* a low level driver may set these to teach IOMMU code about

51
lib/devres.c
View File

@ -85,6 +85,57 @@ void devm_iounmap(struct device *dev, void __iomem *addr)
}
EXPORT_SYMBOL(devm_iounmap);
/**
* devm_request_and_ioremap() - Check, request region, and ioremap resource
* @dev: Generic device to handle the resource for
* @res: resource to be handled
*
* Takes all necessary steps to ioremap a mem resource. Uses managed device, so
* everything is undone on driver detach. Checks arguments, so you can feed
* it the result from e.g. platform_get_resource() directly. Returns the
* remapped pointer or NULL on error. Usage example:
*
* res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
* base = devm_request_and_ioremap(&pdev->dev, res);
* if (!base)
* return -EADDRNOTAVAIL;
*/
void __iomem *devm_request_and_ioremap(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 NULL;
}
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 NULL;
}
if (res->flags & IORESOURCE_CACHEABLE)
dest_ptr = devm_ioremap(dev, res->start, size);
else
dest_ptr = devm_ioremap_nocache(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);
}
return dest_ptr;
}
EXPORT_SYMBOL(devm_request_and_ioremap);
#ifdef CONFIG_HAS_IOPORT
/*
* Generic iomap devres