From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id B2580B6F1A for ; Fri, 27 Nov 2009 10:18:54 +1100 (EST) In-Reply-To: <1259269265.18084.14.camel@pasglop> References: <1258927311-4340-1-git-send-email-albert_herranz@yahoo.es> <1258927311-4340-2-git-send-email-albert_herranz@yahoo.es> <1258927311-4340-3-git-send-email-albert_herranz@yahoo.es> <1258927311-4340-4-git-send-email-albert_herranz@yahoo.es> <1258927311-4340-5-git-send-email-albert_herranz@yahoo.es> <49436.84.105.60.153.1259171377.squirrel@gate.crashing.org> <1259211061.16367.260.camel@pasglop> <4B0E9C5F.50304@yahoo.es> <1259269265.18084.14.camel@pasglop> Mime-Version: 1.0 (Apple Message framework v753.1) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: From: Segher Boessenkool Subject: Re: [RFC PATCH 04/19] powerpc: wii: device tree Date: Fri, 27 Nov 2009 00:25:49 +0100 To: Benjamin Herrenschmidt Cc: Albert Herranz , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >> There you can find the hardware interface that supports the IPC >> mechanism. >> It is made up of a pair of registers to pass data between the >> processors and a >> pair of control/flags registers. >> The hardware can interrupt the PowerPC side when there is data >> available for it. > > Ok. So the right way to do that would be to have a node purely > representing the HW IPC, unrelated to whatever is running on the > secondary processor. Or you can keep it implicit in the Hollywood control registers. It is one 512-byte block with lots of things thrown together (and then mixed up real good). > However, it's ok to have -below- that node, a set of device nodes or a > node with properties or whatever representing the FW in there and the > function it exposes. That's not really useful though, it's easy to probe for. > What might do however is to have a way for that FW itself to > provide you > with the nodes and properties for the functions it provides :-) You get a pointer at the very last word of memory. It point to an info header that has everything you need to know (most importantly, a version identifier). > Of course that wouldn't work with FW we don't have control on. Can > Linux > run on the wii with the original N. FW on the aux. processor ? It _can_, but there are no advantages to doing that, and lots and lots of disadvantages, so the plan is to not add support for that in mainline. > Can we > detect what is running there ? Do we care ? You can detect this for anything that uses a mini-compatible interface. You shouldn't care for anything else ;-) Segher