Return-path: Received: from mail.academy.zt.ua ([82.207.120.245]:58189 "EHLO mail.academy.zt.ua" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757552Ab1DMU00 (ORCPT ); Wed, 13 Apr 2011 16:26:26 -0400 Subject: Re: [RFC][PATCH] axi: add AXI bus driver From: George Kashperko To: =?UTF-8?Q?Rafa=C5=82_Mi=C5=82ecki?= Cc: Arend van Spriel , "balbi@ti.com" , "linux-wireless@vger.kernel.org" , "John W. Linville" , "b43-dev@lists.infradead.org" , Michael =?ISO-8859-1?Q?B=FCsch?= , Larry Finger , "linux-arm-kernel@lists.infradead.org" , Russell King , Arnd Bergmann , Andy Botting , linuxdriverproject , "linux-kernel@vger.kernel.org" In-Reply-To: References: <1302566227-23788-1-git-send-email-zajec5@gmail.com> <20110412133633.GR15130@legolas.emea.dhcp.ti.com> <1302634039.14216.10.camel@dev.znau.edu.ua> <1302635550.14216.21.camel@dev.znau.edu.ua> <4DA4AC4B.90409@hauke-m.de> <1302640546.14216.65.camel@dev.znau.edu.ua> Content-Type: text/plain; charset=utf-8 Date: Wed, 13 Apr 2011 23:23:07 +0300 Message-Id: <1302726187.7911.11.camel@dev.znau.edu.ua> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: > 2011/4/13 Arend van Spriel : > > On Tue, 12 Apr 2011 22:44:01 +0200, Rafał Miłecki wrote: > > > >> 2011/4/12 George Kashperko : > >>>> > >>>> 2011/4/12 Rafał Miłecki : > >>>> That way I see really low (or not at all) relation between out > >>>> (not)Broadcom bus and present AMBA bus. > >>>> > >>> Agree. > >> > >> Ehh, sounds like one more renaming to functions, defines, prefixes. > >> > >> Let's wait for Arend comments, he was the one voting for not-bcm-specific > >> name. > >> > > > > Hi Rafał, > > > > Still think its better to stick with a generic name even if currently you > > only come across this in Broadcom chips right now. I do agree that the term > > 'axi' is implying something else than what this bus driver is providing. The > > name 'axi-dmp' I gave earlier may be more to the point. > > > > I also looked at the amba driver after receiving comments on the brcmaxi > > library module (this is what Hauke Mehrtens referred to) and came to similar > > conclusion as you did. It does however support PM properly so you may want > > to get inspiration in that area. I also noticed a reference to AMBA term APB > > which is a different bus in the AMBA family. AXI was introduced later as > > higher performance bus (in AMBA rev3 if I remember correctly). > > I don't focus on PM yet, do not consider it a problem, it just needs some time. > > Note for not involved: AMBA is family with few buses/interfaces > possible: AXI, AHB, ASB, APB, ATB [1]. > > So what are you saying is that drivers/amba/ is for AMBA APB? OK, I > can accept such a explanation and it makes me even more sure we need > another AMBA driver (this time: AMBA AXI). AMBA is AMBA. axi/apb/ahb etc are all subsets of AMBA and as of current all fit to what already is in drivers/amba. > > The left question is: how much of the implemented code is AMBA AXI > specific and how much is Broadcom specific? Answers to 1. and 2. are there in drivers/amba/bus.c Look _probe and _register fn for more details. > 1) Does AMBA AXI identify cores by manuf, id, rev and class? Is this > really AMBA AXI specific and a evolution from simple "id" in AMBA APB? During amba device registration amba bus code read component/peripheral id registers from known locations, exactly where peripherialid/componentid registers of master port (agent) core are. Look brcm80211/inclue/aidmp.h for those. > 2) Is this standard for AMBA AXI to keep list of available cores in > some specific memory (is this always EPROM like in case of Bcm?)? > 3) Does every AMBA AXI device need enabling/disabling/resetting > routine we implemented? Is that really Bcm independent? Enable/disable abstracted by clocks interface. It would be really great if someone could enligten us on 2). > This is mostly what I already asked, but didn't get answer. Please, > explain to us what is AMBA AXI specific and what is Broadcom specific. > > [1] http://en.wikipedia.org/wiki/Advanced_Microcontroller_Bus_Architecture > Have nice day, George