From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3A5CCA9EA0 for ; Tue, 22 Oct 2019 05:49:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB65621906 for ; Tue, 22 Oct 2019 05:49:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726024AbfJVFtL (ORCPT ); Tue, 22 Oct 2019 01:49:11 -0400 Received: from mail-sz.amlogic.com ([211.162.65.117]:9380 "EHLO mail-sz.amlogic.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725788AbfJVFtL (ORCPT ); Tue, 22 Oct 2019 01:49:11 -0400 Received: from [10.28.19.63] (10.28.19.63) by mail-sz.amlogic.com (10.28.11.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1591.10; Tue, 22 Oct 2019 13:49:20 +0800 Subject: Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver To: Guenter Roeck , Wim Van Sebroeck , Kevin Hilman , Neil Armstrong CC: Rob Herring , Jerome Brunet , Qianggui Song , Jianxin Pan , Jian Hu , , , , References: <1571387622-35132-1-git-send-email-xingyu.chen@amlogic.com> <1571387622-35132-4-git-send-email-xingyu.chen@amlogic.com> <7397f6db-1dc8-3abd-41ff-2e47323c7ffa@roeck-us.net> From: Xingyu Chen Message-ID: <1b841195-cf76-7128-9569-5c2b0d39c1c1@amlogic.com> Date: Tue, 22 Oct 2019 13:49:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit X-Originating-IP: [10.28.19.63] X-ClientProxiedBy: mail-sz.amlogic.com (10.28.11.5) To mail-sz.amlogic.com (10.28.11.5) Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org 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 >>>> --- >>>>   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 > > . >