Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755800AbaGBQAk (ORCPT ); Wed, 2 Jul 2014 12:00:40 -0400 Received: from service87.mimecast.com ([91.220.42.44]:55311 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753627AbaGBQAi convert rfc822-to-8bit (ORCPT ); Wed, 2 Jul 2014 12:00:38 -0400 Date: Wed, 2 Jul 2014 17:00:34 +0100 From: Liviu Dudau To: Will Deacon Cc: linux-pci , Bjorn Helgaas , Catalin Marinas , Benjamin Herrenschmidt , Arnd Bergmann , linaro-kernel , Tanmay Inamdar , Grant Likely , Sinan Kaya , Jingoo Han , Kukjin Kim , Suravee Suthikulanit , LKML , Device Tree ML , LAKML Subject: Re: [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function. Message-ID: <20140702160034.GP2173@e106497-lin.cambridge.arm.com> References: <1404240214-9804-1-git-send-email-Liviu.Dudau@arm.com> <1404240214-9804-4-git-send-email-Liviu.Dudau@arm.com> <20140702112222.GK18731@arm.com> MIME-Version: 1.0 In-Reply-To: <20140702112222.GK18731@arm.com> User-Agent: Mutt/1.5.22 (2013-10-16) X-OriginalArrivalTime: 02 Jul 2014 16:00:35.0683 (UTC) FILETIME=[C2AC8B30:01CF960E] X-MC-Unique: 114070217003514901 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 02, 2014 at 12:22:22PM +0100, Will Deacon wrote: > On Tue, Jul 01, 2014 at 07:43:28PM +0100, Liviu Dudau wrote: > > Some architectures do not have a simple view of the PCI I/O space > > and instead use a range of CPU addresses that map to bus addresses. For > > some architectures these ranges will be expressed by OF bindings > > in a device tree file. > > > > Introduce a pci_register_io_range() helper function with a generic > > implementation that can be used by such architectures to keep track > > of the I/O ranges described by the PCI bindings. If the PCI_IOBASE > > macro is not defined that signals lack of support for PCI and we > > return an error. > > [...] > > > +/* > > + * Record the PCI IO range (expressed as CPU physical address + size). > > + * Return a negative value if an error has occured, zero otherwise > > + */ > > +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size) > > +{ > > +#ifdef PCI_IOBASE > > + struct io_range *res; > > + resource_size_t allocated_size = 0; > > + > > + /* check if the range hasn't been previously recorded */ > > + list_for_each_entry(res, &io_range_list, list) { > > + if (addr >= res->start && addr + size <= res->start + size) > > + return 0; > > + allocated_size += res->size; > > + } > > + > > + /* range not registed yet, check for available space */ > > + if (allocated_size + size - 1 > IO_SPACE_LIMIT) > > + return -E2BIG; > > + > > + /* add the range to the list */ > > + res = kzalloc(sizeof(*res), GFP_KERNEL); > > + if (!res) > > + return -ENOMEM; > > + > > + res->start = addr; > > + res->size = size; > > + > > + list_add_tail(&res->list, &io_range_list); > > + > > + return 0; > > Hopefully a stupid question, but how is this serialised? I'm just surprised > that adding to and searching a list are sufficient, unless there's a big > lock somewhere. Sorry, tripped into my own filters! You are right, there is no serialisation here, will add one. Best regards, Liviu > > Will > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/