From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Tue, 27 Oct 2015 01:41:53 +0100 Subject: [RFC PATCH] clocksource: dw_apb_timer_of: support timer-based delay In-Reply-To: <1445328672-581-1-git-send-email-jszhang@marvell.com> References: <1445328672-581-1-git-send-email-jszhang@marvell.com> Message-ID: <562EC851.3080500@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 10/20/2015 10:11 AM, Jisheng Zhang wrote: > Implement an ARM delay timer to be used for udelay(). This allows us to > skip the delay loop calibration at boot on Marvell BG2, BG2Q, BG2CD > platforms. And after this patch, udelay() will be unaffected by CPU > frequency changes. > > But, this driver is not only used on ARM platforms, so I dunno how to > handle other platforms which don't have the register_current_timer_delay > That's the reason I mark this patch as RFC. > > Any suggestions are appreciated. hmm, may be a dt-binding makes sense... > Signed-off-by: Jisheng Zhang > --- > drivers/clocksource/dw_apb_timer_of.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/clocksource/dw_apb_timer_of.c b/drivers/clocksource/dw_apb_timer_of.c > index a19a3f6..09dbf9c 100644 > --- a/drivers/clocksource/dw_apb_timer_of.c > +++ b/drivers/clocksource/dw_apb_timer_of.c > @@ -16,6 +16,7 @@ > * You should have received a copy of the GNU General Public License > * along with this program. If not, see . > */ > +#include > #include > #include > #include > @@ -130,6 +131,15 @@ static void __init init_sched_clock(void) > sched_clock_register(read_sched_clock, 32, sched_rate); > } > > +static unsigned long dw_apb_delay_timer_read(void) > +{ > + return ~readl_relaxed(sched_io_base); > +} > + > +static struct delay_timer dw_apb_delay_timer = { > + .read_current_timer = dw_apb_delay_timer_read, > +}; > + > static int num_called; > static void __init dw_apb_timer_init(struct device_node *timer) > { > @@ -142,6 +152,8 @@ static void __init dw_apb_timer_init(struct device_node *timer) > pr_debug("%s: found clocksource timer\n", __func__); > add_clocksource(timer); > init_sched_clock(); > + dw_apb_delay_timer.freq = sched_rate; > + register_current_timer_delay(&dw_apb_delay_timer); > break; > default: > break; > -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753386AbbJ0Al5 (ORCPT ); Mon, 26 Oct 2015 20:41:57 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:34151 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751929AbbJ0Alz (ORCPT ); Mon, 26 Oct 2015 20:41:55 -0400 Subject: Re: [RFC PATCH] clocksource: dw_apb_timer_of: support timer-based delay To: Jisheng Zhang , tglx@linutronix.de References: <1445328672-581-1-git-send-email-jszhang@marvell.com> Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Daniel Lezcano Message-ID: <562EC851.3080500@linaro.org> Date: Tue, 27 Oct 2015 01:41:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1445328672-581-1-git-send-email-jszhang@marvell.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/20/2015 10:11 AM, Jisheng Zhang wrote: > Implement an ARM delay timer to be used for udelay(). This allows us to > skip the delay loop calibration at boot on Marvell BG2, BG2Q, BG2CD > platforms. And after this patch, udelay() will be unaffected by CPU > frequency changes. > > But, this driver is not only used on ARM platforms, so I dunno how to > handle other platforms which don't have the register_current_timer_delay > That's the reason I mark this patch as RFC. > > Any suggestions are appreciated. hmm, may be a dt-binding makes sense... > Signed-off-by: Jisheng Zhang > --- > drivers/clocksource/dw_apb_timer_of.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/clocksource/dw_apb_timer_of.c b/drivers/clocksource/dw_apb_timer_of.c > index a19a3f6..09dbf9c 100644 > --- a/drivers/clocksource/dw_apb_timer_of.c > +++ b/drivers/clocksource/dw_apb_timer_of.c > @@ -16,6 +16,7 @@ > * You should have received a copy of the GNU General Public License > * along with this program. If not, see . > */ > +#include > #include > #include > #include > @@ -130,6 +131,15 @@ static void __init init_sched_clock(void) > sched_clock_register(read_sched_clock, 32, sched_rate); > } > > +static unsigned long dw_apb_delay_timer_read(void) > +{ > + return ~readl_relaxed(sched_io_base); > +} > + > +static struct delay_timer dw_apb_delay_timer = { > + .read_current_timer = dw_apb_delay_timer_read, > +}; > + > static int num_called; > static void __init dw_apb_timer_init(struct device_node *timer) > { > @@ -142,6 +152,8 @@ static void __init dw_apb_timer_init(struct device_node *timer) > pr_debug("%s: found clocksource timer\n", __func__); > add_clocksource(timer); > init_sched_clock(); > + dw_apb_delay_timer.freq = sched_rate; > + register_current_timer_delay(&dw_apb_delay_timer); > break; > default: > break; > -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog