From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756112Ab3IZJFx (ORCPT ); Thu, 26 Sep 2013 05:05:53 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:41257 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753758Ab3IZJFv (ORCPT ); Thu, 26 Sep 2013 05:05:51 -0400 Date: Thu, 26 Sep 2013 11:05:44 +0200 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Daniel Lezcano Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@pengutronix.de, John Stultz Subject: Re: [RFC, PATCH] clocksource: provide timekeeping for efm32 SoCs Message-ID: <20130926090544.GJ16106@pengutronix.de> References: <1379324644-20934-1-git-send-email-u.kleine-koenig@pengutronix.de> <5242F434.7060702@linaro.org> <20130925153207.GG16106@pengutronix.de> <524376A0.7020405@linaro.org> <20130926082059.GI16106@pengutronix.de> <5243F5CD.6090709@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5243F5CD.6090709@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:21e:67ff:fe11:9c5c X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Daniel, On Thu, Sep 26, 2013 at 10:52:29AM +0200, Daniel Lezcano wrote: > On 09/26/2013 10:20 AM, Uwe Kleine-König wrote: > >Hello Daniel, > > > >On Thu, Sep 26, 2013 at 01:49:52AM +0200, Daniel Lezcano wrote: > >>On 09/25/2013 05:32 PM, Uwe Kleine-König wrote: > >>>>>+static void __init efm32_timer_init(struct device_node *np) > >>>>>+{ > >>>>>+ static int has_clocksource, has_clockevent; > >>>>>+ int ret; > >>>>>+ > >>>>>+ if (!has_clocksource) { > >>>>>+ ret = efm32_clocksource_init(np); > >>>>>+ if (!ret) { > >>>>>+ has_clocksource = 1; > >>>>>+ return; > >>>>>+ } > >>>>>+ } > >>>>>+ > >>>>>+ if (!has_clockevent) { > >>>>>+ ret = efm32_clockevent_init(np); > >>>>>+ if (!ret) { > >>>>>+ has_clockevent = 1; > >>>>>+ return; > >>>>>+ } > >>>>>+ } > >>>>>+} > >>>> > >>>>I don't get the purpose of this initialization, can you explain ? > >>>An efm32 SoC has four timer blocks. A single block can only be used for > >>>one of clocksource or clockevent device and having more than one > >>>clocksource or clockevent device doesn't make sense. So this routine > >>>asserts that the first timer is used as clocksource and the second as > >>>clockevent device. The others are unused. > >> > >>Shouldn't be up to the dt to give the timers you want ? > >The dt looks as follows: > > > > timer0: timer@40010000 { > > compatible = "efm32,timer"; > > reg = <0x40010000 0x400>; > > interrupts = <2>; > > clocks = <&cmu clk_HFPERCLKTIMER0>; > > }; > > > > timer1: timer@40010400 { > > compatible = "efm32,timer"; > > reg = <0x40010400 0x400>; > > interrupts = <12>; > > clocks = <&cmu clk_HFPERCLKTIMER1>; > > }; > > > > timer2: timer@40010800 { > > compatible = "efm32,timer"; > > reg = <0x40010800 0x400>; > > interrupts = <13>; > > clocks = <&cmu clk_HFPERCLKTIMER2>; > > }; > > > > timer3: timer@40010c00 { > > compatible = "efm32,timer"; > > reg = <0x40010c00 0x400>; > > interrupts = <14>; > > clocks = <&cmu clk_HFPERCLKTIMER3>; > > }; > > > >What is your suggestion now? > >Add a property that specifies if the block > >should be used as clocksource or clockevent_device? That isn't a > >hardware description and so shouldn't go into the device tree. > > At this point, I just asked a question and did not make any suggestion. I thought your question implied knowing a better way. I'd be happy if it did. > >Provide two drivers that match on "efm32,timer", one for clocksource and > >another for clockevent_device? That wouldn't work, too, as the first > >driver to be loaded would grab all four timers and the second would get > >none. > > Thanks, now I understand the purpose of this routine, it is very > similar than: > > http://www.spinics.net/lists/arm-kernel/msg273984.html > > right ? Right. And as tglx points out in that post, it's not pretty, but I don't have an idea how to do it nicer. (BTW, I wonder if the of_node_put in that snipplet is correct, also the three static functions being called could be marked __init.) At least my implementation is a bit more robust as it handles the case that the timer intended to be used as clockevent device doesn't have an irq while the dw_apb_timer driver simply BUGs then. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |