From: Xingyu Chen <xingyu.chen@amlogic.com>
To: Guenter Roeck <linux@roeck-us.net>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Kevin Hilman <khilman@baylibre.com>,
Neil Armstrong <narmstrong@baylibre.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Jerome Brunet <jbrunet@baylibre.com>,
Qianggui Song <qianggui.song@amlogic.com>,
Jianxin Pan <jianxin.pan@amlogic.com>,
Jian Hu <jian.hu@amlogic.com>, <linux-watchdog@vger.kernel.org>,
<linux-amlogic@lists.infradead.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver
Date: Tue, 22 Oct 2019 13:49:20 +0800 [thread overview]
Message-ID: <1b841195-cf76-7128-9569-5c2b0d39c1c1@amlogic.com> (raw)
In-Reply-To: <bd5ed275-4ae4-4163-b585-23fbead9833f@roeck-us.net>
Hi, Guenter
On 2019/10/21 21:38, Guenter Roeck wrote:
> On 10/21/19 1:03 AM, Xingyu Chen wrote:
>> Hi, Guenter
>>
>> On 2019/10/21 0:56, Guenter Roeck wrote:
>>> On 10/18/19 1:33 AM, Xingyu Chen wrote:
>>>> The watchdog controller on the Meson-A/C series SoCs is moved to secure
>>>> world, watchdog operation needs to be done in secure EL3 mode via ATF,
>>>> Non-secure world can call SMC instruction to trap to AFT for watchdog
>>>> operation.
>>>>
>>>> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
>>>> ---
>>>> drivers/watchdog/Kconfig | 17 ++++
>>>> drivers/watchdog/Makefile | 1 +
>>>> drivers/watchdog/meson_sec_wdt.c | 187
>>>> +++++++++++++++++++++++++++++++++++++++
>>>> 3 files changed, 205 insertions(+)
>>>> create mode 100644 drivers/watchdog/meson_sec_wdt.c
>>>>
>>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>>> index 58e7c10..e84be42 100644
>>>> --- a/drivers/watchdog/Kconfig
>>>> +++ b/drivers/watchdog/Kconfig
>>>> @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
>>>> To compile this driver as a module, choose M here: the
>>>> module will be called meson_gxbb_wdt.
>>>> +config MESON_SEC_WATCHDOG
>>>> + tristate "Amlogic Meson Secure watchdog support"
>>>> + depends on MESON_SM
>>>> + depends on ARCH_MESON || COMPILE_TEST
>>>
>>> This dependency is pointless. MESON_SM already depends on ARCH_MESON,
>>> thus specifying "COMPILE_TEST" here adds no value but only
>>> creates confusion.
>> Thanks for your analysis, perhaps i should remove the line below.
>> - depends on ARCH_MESON || COMPILE_TEST
>>
>> Is it ok to modify code above like this ?
>
> Yes.
Thanks, fix it in next version.
> [ ... ]
>
>>>> +static unsigned int meson_sec_wdt_get_timeleft(struct
>>>> watchdog_device *wdt_dev)
>>>> +{
>>>> + int ret;
>>>> + unsigned int timeleft;
>>>> + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>>> +
>>>> + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, Thanks&timeleft,
>>>> + MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
>>>> +
>>>> + if (ret)
>>>> + return ret;
>>>
>>> Meh, that doesn't work. I just realized that the return type is
>>> unsigned,
>>> so returning a negative error code is pointless. Guess we'll have to
>>> live with returning 0 in this case after all. I wonder if we should
>>> fix the API and return an integer (with negative error code), but that
>>> is a different question.
>> Thanks for your review.
>>
>> IMO, if returning an integer, and the value which copy to user buf
>> should be formatted with %d instead of %u (see timeleft_show), it will
>> cause the max value of timeleft is reduced from 4294967295 to
>> 2147483647. but i'am not sure whether it will bring risk.
>
> Not that it matters right now, but I don't think that limiting 'timeleft'
> reporting to 2147483647 seconds, or ~68 years, would cause any risk.
> It would just be a large patch changing several drivers all at once,
> that is all.
>
>>
>> So i also think returning 0 may be better in this case.
>
> Yes, please do that.
Thanks, fix it in next version.
>
> Thanks,
> Guenter
>
> .
>
next prev parent reply other threads:[~2019-10-22 5:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 8:33 [PATCH v2 0/4] add meson secure watchdog driver Xingyu Chen
2019-10-18 8:33 ` [PATCH v2 1/4] firmware: meson_sm: add new SMC ID support for accessing secure watchdog Xingyu Chen
2019-10-18 8:33 ` [PATCH v2 2/4] dt-bindings: watchdog: add new binding for meson " Xingyu Chen
2019-10-18 8:33 ` [PATCH v2 3/4] watchdog: add meson secure watchdog driver Xingyu Chen
2019-10-20 16:56 ` Guenter Roeck
2019-10-21 8:03 ` Xingyu Chen
2019-10-21 13:38 ` Guenter Roeck
2019-10-22 5:49 ` Xingyu Chen [this message]
2019-10-18 8:33 ` [PATCH v2 4/4] arm64: dts: a1: add secure watchdog controller Xingyu Chen
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