From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH V2 13/14] dt-bindings: arm-gic: Add documentation for Tegra210 AGIC Date: Fri, 22 Apr 2016 12:22:39 +0100 Message-ID: <20160422112239.GF10606@leverpostej> References: <1461150237-15580-1-git-send-email-jonathanh@nvidia.com> <1461150237-15580-14-git-send-email-jonathanh@nvidia.com> <20160422100052.GA10606@leverpostej> <571A0739.3090502@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <571A0739.3090502-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jon Hunter Cc: Thomas Gleixner , Jason Cooper , Marc Zyngier , Rob Herring , Pawel Moll , Ian Campbell , Kumar Gala , Stephen Warren , Thierry Reding , Kevin Hilman , Geert Uytterhoeven , Grygorii Strashko , Lars-Peter Clausen , Linus Walleij , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On Fri, Apr 22, 2016 at 12:12:57PM +0100, Jon Hunter wrote: > > On 22/04/16 11:00, Mark Rutland wrote: > > On Wed, Apr 20, 2016 at 12:03:56PM +0100, Jon Hunter wrote: > >> The Tegra AGIC interrupt controller is compatible with the ARM GIC-400 > >> interrupt controller. > > > > The cover letter says it _is_ a GIC-400, just used in a slightly unusual > > manner (i.e. not directly connected to CPUs). > > Correct. > > >> The Tegra AGIC requires two clocks, namely the > >> "ape" (functional) and "apb2ape" (interface) clocks, to operate. Add > >> the compatible string and clock information for the AGIC to the GIC > >> device-tree binding documentation. > > > > The GIC-400 spec only describes "CLK" (which is what I imagine "ape" is. > > There isn't an APB clock described, and the manual seems to show GIC-400 > > directly connected to AXI rather than APB, so that doesn't seem to even > > be the usual "apb_pclk". > > > > Is there some wrapper logic around a GIC-400 to giove it an APB > > interface? Or am I misudnerstanding the spec? > > Looking at the Tegra documentation what we have is ... > > APB --> AXI switch --> AGIC (GIC400) > > I am not sure how such a switch would typically be modeled in DT but we > need the apb clock to interface to the GIC registers. I am not sure if > something like simple-pm-bus is appropriate here. I think we need some representation of that AXI switch in the DT; whether simple-pm-bus is appropriate is another question. We probably need a specific compatible string / binding regardless. Thanks, Mark. > > >> Signed-off-by: Jon Hunter > >> --- > >> > >> I am not sure if it will be popular to add Tegra specific clock names > >> to the GIC DT docs. However, in that case, then possibly the only > >> alternative is to move the Tegra AGIC driver into its own file and > >> expose the GIC APIs for it to use. Then we could add our own DT doc > >> for the Tegra AGIC as well (based upon the ARM GIC). > > > > The clock-names don't seem right to me, as they sound like provide names > > or global clock line names rather than consumer-side names ("clk" and > > "apb_pclk"). > > Yes that would be fine with me. Ok; if we model the apb_pclk as owned by the AXI switch (which it is), then there's no change for the GIC binding, short of the additional compatible string as an extension of "arm,gic-400", as we already model that clock in the GIC-400 binding. Thanks, Mark. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753539AbcDVLW6 (ORCPT ); Fri, 22 Apr 2016 07:22:58 -0400 Received: from foss.arm.com ([217.140.101.70]:33235 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751707AbcDVLW4 (ORCPT ); Fri, 22 Apr 2016 07:22:56 -0400 Date: Fri, 22 Apr 2016 12:22:39 +0100 From: Mark Rutland To: Jon Hunter Cc: Thomas Gleixner , Jason Cooper , Marc Zyngier , Rob Herring , Pawel Moll , Ian Campbell , Kumar Gala , Stephen Warren , Thierry Reding , Kevin Hilman , Geert Uytterhoeven , Grygorii Strashko , Lars-Peter Clausen , Linus Walleij , linux-tegra@vger.kernel.org, linux-omap@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 13/14] dt-bindings: arm-gic: Add documentation for Tegra210 AGIC Message-ID: <20160422112239.GF10606@leverpostej> References: <1461150237-15580-1-git-send-email-jonathanh@nvidia.com> <1461150237-15580-14-git-send-email-jonathanh@nvidia.com> <20160422100052.GA10606@leverpostej> <571A0739.3090502@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <571A0739.3090502@nvidia.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 22, 2016 at 12:12:57PM +0100, Jon Hunter wrote: > > On 22/04/16 11:00, Mark Rutland wrote: > > On Wed, Apr 20, 2016 at 12:03:56PM +0100, Jon Hunter wrote: > >> The Tegra AGIC interrupt controller is compatible with the ARM GIC-400 > >> interrupt controller. > > > > The cover letter says it _is_ a GIC-400, just used in a slightly unusual > > manner (i.e. not directly connected to CPUs). > > Correct. > > >> The Tegra AGIC requires two clocks, namely the > >> "ape" (functional) and "apb2ape" (interface) clocks, to operate. Add > >> the compatible string and clock information for the AGIC to the GIC > >> device-tree binding documentation. > > > > The GIC-400 spec only describes "CLK" (which is what I imagine "ape" is. > > There isn't an APB clock described, and the manual seems to show GIC-400 > > directly connected to AXI rather than APB, so that doesn't seem to even > > be the usual "apb_pclk". > > > > Is there some wrapper logic around a GIC-400 to giove it an APB > > interface? Or am I misudnerstanding the spec? > > Looking at the Tegra documentation what we have is ... > > APB --> AXI switch --> AGIC (GIC400) > > I am not sure how such a switch would typically be modeled in DT but we > need the apb clock to interface to the GIC registers. I am not sure if > something like simple-pm-bus is appropriate here. I think we need some representation of that AXI switch in the DT; whether simple-pm-bus is appropriate is another question. We probably need a specific compatible string / binding regardless. Thanks, Mark. > > >> Signed-off-by: Jon Hunter > >> --- > >> > >> I am not sure if it will be popular to add Tegra specific clock names > >> to the GIC DT docs. However, in that case, then possibly the only > >> alternative is to move the Tegra AGIC driver into its own file and > >> expose the GIC APIs for it to use. Then we could add our own DT doc > >> for the Tegra AGIC as well (based upon the ARM GIC). > > > > The clock-names don't seem right to me, as they sound like provide names > > or global clock line names rather than consumer-side names ("clk" and > > "apb_pclk"). > > Yes that would be fine with me. Ok; if we model the apb_pclk as owned by the AXI switch (which it is), then there's no change for the GIC binding, short of the additional compatible string as an extension of "arm,gic-400", as we already model that clock in the GIC-400 binding. Thanks, Mark.