From mboxrd@z Thu Jan 1 00:00:00 1970 From: w.sang@pengutronix.de (Wolfram Sang) Date: Mon, 24 Oct 2011 22:09:33 +0200 Subject: [RFC 3/4] lib: devres: add convenience function to remap a resource In-Reply-To: <20111024154307.GB24914@google.com> References: <1319445729-14841-1-git-send-email-w.sang@pengutronix.de> <1319445729-14841-4-git-send-email-w.sang@pengutronix.de> <20111024154307.GB24914@google.com> Message-ID: <20111024200933.GB6326@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, > 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. I had this name in mind, too. Yet, it implies that the function requests a resource but in fact it requests a mem_region. Requesting a resource (e.g. platform_get_resource) is THE thing the function does not do. So I scrapped this name. But will do some more brainstorming for a better name in V2. > > > +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. Yes, already fixed this way. > > +{ > > + 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; I am not sure I got what you mean here, but wouldn't it be easier to simply call devm_release_mem_region() when devm_ioremap comes back with a NULL pointer? Thanks, Wolfram -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: