From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753056AbbDBLNF (ORCPT ); Thu, 2 Apr 2015 07:13:05 -0400 Received: from bear.ext.ti.com ([192.94.94.41]:36308 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752420AbbDBLNB (ORCPT ); Thu, 2 Apr 2015 07:13:01 -0400 Message-ID: <551D241C.8040709@ti.com> Date: Thu, 2 Apr 2015 16:42:28 +0530 From: Lokesh Vutla User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Alexandre Belloni , CC: , , , , Subject: Re: [rtc-linux] [PATCH 1/3] rtc: omap: Unlock and Lock rtc registers before and after register writes References: <1427867698-1326-1-git-send-email-lokeshvutla@ti.com> <1427867698-1326-2-git-send-email-lokeshvutla@ti.com> <20150401155204.GC20669@piout.net> In-Reply-To: <20150401155204.GC20669@piout.net> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wednesday 01 April 2015 09:22 PM, Alexandre Belloni wrote: > Hi, > > On 01/04/2015 at 11:24:56 +0530, Lokesh Vutla wrote : >> RTC module contains a kicker mechanism to prevent any spurious writes >> from changing the register values. This mechanism requires two MMR >> writes to the KICK0 and KICK1 registers with exact data values >> before the kicker lock mechanism is released. >> >> Currently the driver release the lock in the probe and leaves it enabled >> until the rtc driver removal. This eliminates the idea of preventing >> spurious writes when RTC driver is loaded. >> So implement rtc lock and unlock functions before and after register writes. >> >> Signed-off-by: Lokesh Vutla >> --- >> - This is as advised by Paul to implement lock and unlock functions in >> the driver and not to unlock and leave it in probe. >> The same discussion can be seen here: >> http://www.mail-archive.com/linux-omap%40vger.kernel.org/msg111588.html >> >> drivers/rtc/rtc-omap.c | 46 ++++++++++++++++++++++++++++++++++++++-------- >> 1 file changed, 38 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c >> index 8e5851a..96cc613 100644 >> --- a/drivers/rtc/rtc-omap.c >> +++ b/drivers/rtc/rtc-omap.c >> @@ -156,6 +156,22 @@ static inline void rtc_writel(struct omap_rtc *rtc, unsigned int reg, u32 val) >> writel(val, rtc->base + reg); >> } >> >> +static void rtc_unlock(struct omap_rtc *rtc) >> +{ >> + if (rtc->type->has_kicker) { > > Instead of testing for has_kicker each time, I would add .lock and > .unlock to omap_rtc_device_type and directly use rtc->type->lock and > rtc->type->unlock. Makes sense. I have posted v2 of my series updating this. Thanks and regards, Lokesh > >> + rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE); >> + rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE); >> + } >> +} >> +