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 1iRwFu-0000lG-13 for barebox@lists.infradead.org; Tue, 05 Nov 2019 10:40:11 +0000 Date: Tue, 5 Nov 2019 11:40:08 +0100 From: Sascha Hauer Message-ID: <20191105104008.qrivs4orphopplzz@pengutronix.de> References: <20191104221407.14791-1-a.fatoum@pengutronix.de> <20191104221407.14791-2-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191104221407.14791-2-a.fatoum@pengutronix.de> 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: Ahmad Fatoum Cc: barebox@lists.infradead.org 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(). 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. > @@ -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. 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