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Miller" , Jonathan Cameron , Mauro Carvalho Chehab , Wim Van Sebroeck , Greg Kroah-Hartman , Mark Rutland , linux-watchdog@vger.kernel.org Subject: Re: [PATCH 1/2] dt-bindings: watchdog: Add arm,smc-wdt watchdog arm,smc-wdt compatible Message-ID: <20200219232005.GA9737@roeck-us.net> References: <20200214062637.216209-1-evanbenn@chromium.org> <20200214172512.1.I02ebc5b8743b1a71e0e15f68ea77e506d4e6f840@changeid> <20200219223046.GA16537@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Wed, Feb 19, 2020 at 03:04:54PM -0800, Julius Werner wrote: > > You are not the first 'watchdog in firmware accessed via an SMC call'. > > Is there some more detail about what implementation this is? Part of > > TF-A? Defined by some spec (I can dream)? > > This is just some random implementation written by me because we > needed one. I would like it to be the new generic implementation, but > it sounds like people here prefer the naming to be MediaTek specific > (at least for now). The other SMC watchdog we're aware of is > imx_sc_wdt but unfortunately that seems to hardcode platform-specific There is one more pending, for Meson SMC. https://patchwork.kernel.org/project/linux-watchdog/list/?series=227733 Unfortunately it uses Meson firmware API functions, though it has pretty much the same functionality since those ultimately end up calling arm_smccc_smc(). Guenter > details in the interface (at least in the pretimeout SMC) so we can't > just expand that. With this driver I tried to directly wrap the kernel > watchdog interface so it should be platform-agnostic and possible to > expand this driver to other platforms later if desired. The SMC > function ID would still always have to be platform-specific, > unfortunately (but we could pass it in through the device tree), since > the Arm SMC spec doesn't really leave any room for OS-generic SMCs > like this.