Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755627AbcKKKtB (ORCPT ); Fri, 11 Nov 2016 05:49:01 -0500 Received: from foss.arm.com ([217.140.101.70]:40078 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576AbcKKKs7 (ORCPT ); Fri, 11 Nov 2016 05:48:59 -0500 Date: Fri, 11 Nov 2016 10:48:57 +0000 From: "liviu.dudau@arm.com" To: Arnd Bergmann Cc: Gabriele Paoloni , "linux-arm-kernel@lists.infradead.org" , Yuanzhichang , "mark.rutland@arm.com" , "devicetree@vger.kernel.org" , "lorenzo.pieralisi@arm.com" , "minyard@acm.org" , "linux-pci@vger.kernel.org" , "benh@kernel.crashing.org" , John Garry , "will.deacon@arm.com" , "linux-kernel@vger.kernel.org" , "xuwei (O)" , Linuxarm , "zourongrong@gmail.com" , "robh+dt@kernel.org" , "kantyzc@163.com" , "linux-serial@vger.kernel.org" , "catalin.marinas@arm.com" , "olof@lixom.net" , "bhelgaas@google.com" , "zhichang.yuan02@gmail.com" Subject: Re: [PATCH V5 3/3] ARM64 LPC: LPC driver implementation on Hip06 Message-ID: <20161111104857.GI10219@e106497-lin.cambridge.arm.com> References: <1478576829-112707-1-git-send-email-yuanzhichang@hisilicon.com> <17821285.aIcTyCGn5n@wuerfel> <10334260.ztLXZ2Oynd@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <10334260.ztLXZ2Oynd@wuerfel> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2694 Lines: 72 Hi Arnd, On Thu, Nov 10, 2016 at 05:07:21PM +0100, Arnd Bergmann wrote: > On Thursday, November 10, 2016 3:36:49 PM CET Gabriele Paoloni wrote: > > > > Where should we get the range from? For LPC we know that it is going > > Work on anything that is not used by PCI I/O space, and this is > > why we use [0, PCIBIOS_MIN_IO] > > It should be allocated the same way we allocate PCI config space > segments. This is currently done with the io_range list in > drivers/pci/pci.c, which isn't perfect but could be extended > if necessary. Based on what others commented here, I'd rather > make the differences between ISA/LPC and PCI I/O ranges smaller > than larger. > > > > Your current version has > > > > > > if (arm64_extio_ops->pfout) \ > > > arm64_extio_ops->pfout(arm64_extio_ops->devpara,\ > > > addr, value, sizeof(type)); \ > > > > > > Instead, just subtract the start of the range from the logical > > > port number to transform it back into a bus-local port number: > > > > These accessors do not operate on IO tokens: > > > > If (arm64_extio_ops->start > addr || arm64_extio_ops->end < addr) > > addr is not going to be an I/O token; in fact patch 2/3 imposes that > > the I/O tokens will start at PCIBIOS_MIN_IO. So from 0 to PCIBIOS_MIN_IO > > we have free physical addresses that the accessors can operate on. > > Ah, I missed that part. I'd rather not use PCIBIOS_MIN_IO to refer to > the logical I/O tokens, the purpose of that macro is really meant > for allocating PCI I/O port numbers within the address space of > one bus. > > Note that it's equally likely that whichever next platform needs > non-mapped I/O access like this actually needs them for PCI I/O space, > and that will use it on addresses registered to a PCI host bridge. > > If we separate the two steps: > > a) assign a range of logical I/O port numbers to a bus Except that currently when we add ranges to io_range_list we don't have a bus number yet, because the parsing happens before the host bridge has been created. Maybe register_io_range() can take a bus number as an argument, but I'm not sure how we are going to use that in pci_pio_to_address() or pci_address_to_pio(). Best regards, Liviu > b) register a set of helpers for redirecting logical I/O > port to a helper function > > then I think the code will get cleaner and more flexible. > It should actually then be able to replace the powerpc > specific implementation. > > Arnd -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯