From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753215Ab2L0QIP (ORCPT ); Thu, 27 Dec 2012 11:08:15 -0500 Received: from moutng.kundenserver.de ([212.227.17.10]:63377 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753072Ab2L0QIN (ORCPT ); Thu, 27 Dec 2012 11:08:13 -0500 From: Arnd Bergmann To: anish kumar Subject: Re: What does ISA/PCI really mean to ARM architecture? Date: Thu, 27 Dec 2012 16:07:23 +0000 User-Agent: KMail/1.12.2 (Linux/3.7.0-7-generic; KDE/4.3.2; x86_64; ; ) Cc: Geert Uytterhoeven , Woody Wu , kernelnewbies@kernelnewbies.org, "linux-kernel" References: <20121227082724.GA11775@zuhnb712.ap.bm.net> <1356617960.5433.32.camel@anish-Inspiron-N5050> In-Reply-To: <1356617960.5433.32.camel@anish-Inspiron-N5050> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201212271607.24201.arnd@arndb.de> X-Provags-ID: V02:K0:qqmK2ArB5cYO6BjlWn0L6Q3EAvGud+4eL6dfHzns26a d+fgSnNoRBhjKSaboAq0jifRgNXD/4ATvvkdDMrTqwdV0WCncx s7R4aTQdHEzjJFsdnwTnbpkO5q5V+i7QMsidfFFhH5bCwC4JCn Yrb2O3v+pzlxMIlnz2Sv1Soj0GgCrIeq0rrREDp/YBB9lrltM7 EFYNT15iDXafcSmPg+AAMAJg988qoShwpHUsoQtiunW4yvy/jg xf6IlxfMmPGwOI2pMCL9W4PPGpwBz6Ovq2iBGD3opvkW/IK5WL L2TkAijQFhZO4gDERSwfECGzQLYrXi3PuQ/zECXPvUsVrlNP1X EwnF68dETUFRiHN9vV7I= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 27 December 2012, anish kumar wrote: > On Thu, 2012-12-27 at 10:51 +0100, Geert Uytterhoeven wrote: > > On Thu, Dec 27, 2012 at 9:27 AM, Woody Wu wrote: > > > Can a peripheral chip that claims to be ISA or PCI device be used in a > > > ARM based embedded system? For these kind of chips, I only concern > > > about the planar kind of devices, means they are not on a dedicated > > > expansion card. > > > > > > From hardware point of view, to attach a ISA or PCI planar chip, is > > > there any requirement need to fulfill on a ARM bard? > arm AFAIK is only used in embedded system but ISA/PCI buses are > generally part of 'big systems' and most of the times it refers to x86 > PC. In the old days, there were a few ARM based systems that were closer to what we think of as a PC, and that had actual ISA slots, or (more commonly) PCMCIA, which is related to ISA. Aside from that, there are and have been for a long time some ARM systems that have PCI or PCIe slots. Note that the distinction between ISA-style platform devices and ISA add-on cards is a little fuzzy. The Kconfig option CONFIG_ISA refers to the latter, but there are also ARM systems that only have the former, e.g. for floppy controller. > > > From Linux driver point of view, what are needed to support an ISA or > > > PCI driver in ARM architecture? More important, is ISA or PCI device a > > > platform device? If not, how to add these kind of devices in my board > > > definition? > > AFAIK, Platform device is just a way to add a particular driver whose > probe can't be called at runtime. Mostly platform device is part of > system on chip. Right. Note that some ISA devices (especially those that are typically on-board) are platform devices as well, but PCI devices never are. > > An ISA device is typically a platform device. For ARM, which uses device trees, > Don't know much about ISA device to comment on this but people familiar > with this can enlighten us as to the reason why it is platform device in > detail. Classic ISA has no way to probe the presence of a device, so platform devices were introduced to handle those. There is also ISAPNP, which adds PCI-like probing on top of ISA, but most ISA cards precede that standard. Arnd