From mboxrd@z Thu Jan 1 00:00:00 1970 From: Davide Rizzo Subject: Re: [PATCH 1/2] User access to internal clocks Date: Mon, 9 Feb 2009 19:17:07 +0100 Message-ID: <8447d6730902091017m21cb30d0w6be6fbbbf33db4f3@mail.gmail.com> References: <8447d6730902090904y138af9c6r3d64278bc7a30811@mail.gmail.com> <20090209171042.GA19453@n2100.arm.linux.org.uk> <8447d6730902090944s9bc96f7r76da82ea09c629f0@mail.gmail.com> <20090209175514.GB19453@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090209175514.GB19453-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Russell King - ARM Linux Cc: gregkh-l3A5Bk7waGM@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org > You're not understanding the issue(s). > > 1. there is no 1:1 mapping between the identifiers (struct device + > connection ID) and the struct clk. It's actually a many-to-one > mapping. > > That means there is _no_ name associated with a struct clk. > > Conceptually, clk_get() gives you a struct clk for the struct device > and a connection ID. How that mapping is achieved isn't specified > in the API, all that's required is that such a mapping is performed. > It is _specifically_ intended that more than one set of {device,id} > pairs will map to the same clk. > > So, now to insist that you can go from a struct clk to some kind of > string identifier for it is changing this - you're now requiring > that every struct clk has a unique name. This is not the case. > PXA, for instance, struct clk's are now completely nameless. They > have no identifier. > > If you want to have a string identifier which works in every case, > this will: > > sprintf(identifer, "%p", clk); > > Or, I guess you could force every struct clk to have a 'sysfs_name' > field just to export them out via sysfs - and that'll be all that > it's used for. > > 2. there is no generic way to walk a set of struct clk's - indeed, there > may be no list of them (and there exists implmentations where that is > true) and the only list which does exist is a set ID to clk mapping > structures. > >> Otherwise, what do you suggest to enumerate and distinguish all system >> clocks ? > > There exists no such concept in the API, what you're asking for is > implementation specific. > Thank you for this explanation, now it's much more clear to me. What about adding a dedicated function to clk api that registers a struct clk in a linked list and associates it with a name, with the only specific purpose to enumerate and list (and possibly change rate and parents) all clocks in sysfs ? Obviously only specifically registered clocks will be visible in sysfs... -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html