From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iRwLt-0003oJ-BW for barebox@lists.infradead.org; Tue, 05 Nov 2019 10:46:22 +0000 References: <20191104221407.14791-1-a.fatoum@pengutronix.de> <20191104221407.14791-2-a.fatoum@pengutronix.de> <20191105104008.qrivs4orphopplzz@pengutronix.de> From: Ahmad Fatoum Message-ID: <9c68dcf1-5033-efa5-66b5-50679f1ca6b0@pengutronix.de> Date: Tue, 5 Nov 2019 11:46:18 +0100 MIME-Version: 1.0 In-Reply-To: <20191105104008.qrivs4orphopplzz@pengutronix.de> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH v2 2/4] watchdog: implement generic support for .running device parameter To: Sascha Hauer Cc: barebox@lists.infradead.org Hi, On 11/5/19 11:40 AM, Sascha Hauer wrote: > Hi Ahmad, > > On Mon, Nov 04, 2019 at 11:14:05PM +0100, Ahmad Fatoum wrote: >> Linux watchdog have an optional WDOG_HW_RUNNING bit that is used in >> conjunction with CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED to automatically >> ping running watchdogs until userspace takes over. >> >> So far, when we ported Linux drivers, we dropped this detection, but it >> would be useful to have this information in barebox as well: >> >> The American Megatrends BIOS I am using allows configuring the hardware >> watchdog from the BIOS. barebox enables the WDT as well, so in normal >> operation we would never notice if after a BIOS update, the watchdog is >> no longer enabled. If we maintain a running parameter on watchdog >> devices, board code can be written to check whether the watchdog device >> is indeed running. > > To write such code I would prefer to have a function which returns the > running status rather than playing with getenv(). Ye, board code can use watchdog_hw_running added in this patch. Hush scripts can use the device parameter. I'll amend the commit message. > Additionally there is > a function missing in the watchdog code which returns a watchdog by its > name. This can be a future excercise, no need to do it in this patch. Ok. > >> @@ -45,7 +47,18 @@ int watchdog_set_timeout(struct watchdog *wd, unsigned timeout) >> >> pr_debug("setting timeout on %s to %ds\n", watchdog_name(wd), timeout); >> >> - return wd->set_timeout(wd, timeout); >> + ret = wd->set_timeout(wd, timeout); >> + if (ret) >> + return ret; >> + >> + if (test_bit(WDOG_HW_RUNNING_SUPPORTED, &wd->status)) { >> + if (timeout) >> + set_bit(WDOG_HW_RUNNING, &wd->status); >> + else >> + clear_bit(WDOG_HW_RUNNING, &wd->status); >> + } > > When we just started the watchdog we actually know that it is running, > so we could support the parameter for all watchdogs once it's started. > >> + >> + return 0; >> } >> EXPORT_SYMBOL(watchdog_set_timeout); >> >> @@ -118,6 +131,15 @@ static int watchdog_register_poller(struct watchdog *wd) >> return PTR_ERR_OR_ZERO(p); >> } >> >> +static const char *watchdog_get_running(struct device_d *dev, struct param_d *p) >> +{ >> + /* >> + * This won't ever fail, because the parameter is only registed when >> + * test_bit(WDOG_HW_RUNNING_SUPPORTED, &w->status) is true >> + */ >> + return watchdog_hw_running((struct watchdog *)p->value) ? "1" : "0"; >> +} > > Casting p->value to (struct watchdog *) seems wrong. However, this > function shouldn't be needed, see below. > >> + >> static int watchdog_register_dev(struct watchdog *wd, const char *name, int id) >> { >> wd->dev.parent = wd->hwdev; >> @@ -162,6 +184,15 @@ int watchdog_register(struct watchdog *wd) >> if (ret) >> return ret; >> >> + if (test_bit(WDOG_HW_RUNNING_SUPPORTED, &wd->status)) { >> + p = dev_add_param(&wd->dev, "running", NULL, >> + watchdog_get_running, PARAM_FLAG_RO); >> + if (IS_ERR(p)) >> + return PTR_ERR(p); >> + >> + p->value = (char *)wd; >> + } > > How about adding this parameter unconditionally, with "unknown" as value > when WDOG_HW_RUNNING_SUPPORTED is not set. You can use > dev_add_param_enum() here. Sounds good. > > Sascha > -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox