From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
To: rtc-linux@googlegroups.com
Cc: a.zummo@towertech.it, t-kristo@ti.com, nsekhar@ti.com,
linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org,
lokeshvutla@ti.com
Subject: Re: [rtc-linux] [PATCH 1/3] rtc: omap: Unlock and Lock rtc registers before and after register writes
Date: Wed, 1 Apr 2015 17:52:04 +0200 [thread overview]
Message-ID: <20150401155204.GC20669@piout.net> (raw)
In-Reply-To: <1427867698-1326-2-git-send-email-lokeshvutla@ti.com>
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 <lokeshvutla@ti.com>
> ---
> - 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.
> + rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE);
> + rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE);
> + }
> +}
> +
--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-04-01 15:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-01 5:54 [PATCH 0/3] rtc: omap: Fix misc bugs Lokesh Vutla
2015-04-01 5:54 ` [PATCH 1/3] rtc: omap: Unlock and Lock rtc registers before and after register writes Lokesh Vutla
2015-04-01 15:52 ` Alexandre Belloni [this message]
2015-04-02 11:12 ` [rtc-linux] " Lokesh Vutla
2015-04-01 5:54 ` [PATCH 2/3] rtc: omap: Update Kconfig for OMAP RTC Lokesh Vutla
2015-04-01 15:52 ` [rtc-linux] " Alexandre Belloni
2015-04-01 5:54 ` [PATCH 3/3] rtc: omap: use module_platform_driver Lokesh Vutla
2015-04-01 15:53 ` [rtc-linux] " Alexandre Belloni
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150401155204.GC20669@piout.net \
--to=alexandre.belloni@free-electrons.com \
--cc=a.zummo@towertech.it \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=lokeshvutla@ti.com \
--cc=nsekhar@ti.com \
--cc=rtc-linux@googlegroups.com \
--cc=t-kristo@ti.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).