[RFC 3/4] lib: devres: add convenience function to remap a resource
Tejun Heo
tj at kernel.org
Mon Oct 24 11:43:07 EDT 2011
Hello,
On Mon, Oct 24, 2011 at 10:42:08AM +0200, Wolfram Sang wrote:
> * the new function is not named 'devm_ioremap_resource' because it does more than
> just ioremap, namely request_mem_region. I didn't want to create implicit
> knowledge here.
Maybe devm_request_and_ioremap_resource()? Maybe it's a bit long but
A_to_B names are usually used for trivial conversions.
> +int __must_check devm_resource_to_mapped_ptr(struct device *dev,
> + struct resource *res, void __iomem **dest)
If we're already printing out dev_err(), I think we can live with
%NULL return on error.
> +{
> + resource_size_t size;
> + const char *name;
> +
> + BUG_ON(!dev || !dest);
> +
> + *dest = NULL;
> +
> + if (!res || resource_type(res) != IORESOURCE_MEM) {
> + dev_err(dev, "invalid resource\n");
> + return -ENOENT;
> + }
> +
> + 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 -EBUSY;
> + }
> +
> + if (res->flags & IORESOURCE_CACHEABLE)
> + *dest = devm_ioremap(dev, res->start, size);
> + else
> + *dest = devm_ioremap_nocache(dev, res->start, size);
> +
> + if (!*dest) {
> + dev_err(dev, "ioremap failed for resource %pR\n", res);
> + return -ENOMEM;
> + }
So, for library functions, it's nice if the function doesn't hold any
extra resource on error return. devres has grouping to support this.
You just need to wrap allocations inside a group and remove it on
success and release on error. ie.
if (!devres_open_group(dev, NULL, GFP_KERNEL))
return NULL;
if (alloc_resource(0) < 0)
goto fail;
if (alloc_resource(1) < 0)
goto fail;
devres_remove_group(dev, NULL);
return 0;
fail:
devres_release_group(dev, NULL);
return 0;
Thanks.
--
tejun
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