From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH v5 1/5] arm/arm64: add smccc ARCH32 Date: Thu, 20 Aug 2015 22:30:29 +0100 Message-ID: <20150820213029.GA1426@svinekod> References: <1439973629-19505-1-git-send-email-jens.wiklander@linaro.org> <1439973629-19505-2-git-send-email-jens.wiklander@linaro.org> <20150819165009.GC10297@arm.com> <20150820113729.GA25962@ermac> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150820113729.GA25962@ermac> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jens Wiklander Cc: Will Deacon , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Arnd Bergmann , Greg Kroah-Hartman , Kees Cook , "valentin.manea-hv44wF8Li93QT0dZR+AlfA@public.gmane.org" , "javier-5MUHepqpBA1BDgjK7y7TUQ@public.gmane.org" , "emmanuel.michel-qxv4g6HH51o@public.gmane.org" , Michal Simek , "jean-michel.delorme-qxv4g6HH51o@public.gmane.org" , Jason Gunthorpe , Rob Herring List-Id: devicetree@vger.kernel.org On Thu, Aug 20, 2015 at 12:37:29PM +0100, Jens Wiklander wrote: > On Wed, Aug 19, 2015 at 05:50:09PM +0100, Will Deacon wrote: > > On Wed, Aug 19, 2015 at 09:40:25AM +0100, Jens Wiklander wrote: > > > Adds helpers to do SMC based on ARM SMC Calling Convention. > > > CONFIG_HAVE_SMCCC is enabled for architectures that may support > > > the SMC instruction. It's the responsibility of the caller to > > > know if the SMC instruction is supported by the platform. [...] > > > + mov x28, x0 > > > + ldp w0, w1, [x28, #SMC_PARAM_W0_OFFS] > > > + ldp w2, w3, [x28, #SMC_PARAM_W2_OFFS] > > > + ldp w4, w5, [x28, #SMC_PARAM_W4_OFFS] > > > + ldp w6, w7, [x28, #SMC_PARAM_W6_OFFS] > > > + smc #0 > > > + stp w0, w1, [x28, #SMC_PARAM_W0_OFFS] > > > + stp w2, w3, [x28, #SMC_PARAM_W2_OFFS] > > > + ldp x28, x30, [sp], #16 > > > + ret > > > +ENDPROC(smccc_call32) > > > > Could we deal with this like we do for PSCI instead? (see > > __invoke_psci_fn_smc). We could also then rename psci-call.S to fw-call.S > > and stick this in there too. > > I assume you're referring to when to use "hvc" and "smc". I assume he's on about passing the values in registers rather than a struct. >>From the looks of the SMC Calling Convention documentation, it's valid to have return values in registers r0-r3, which necessitates the use of a struct (at least for the return values). Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html