From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936154AbdDSWJF (ORCPT ); Wed, 19 Apr 2017 18:09:05 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:34305 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935995AbdDSWJD (ORCPT ); Wed, 19 Apr 2017 18:09:03 -0400 Date: Wed, 19 Apr 2017 17:09:00 -0500 From: Rob Herring To: Philipp Zabel Cc: Peter Rosin , Mark Rutland , Sakari Ailus , Steve Longerbeam , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de Subject: Re: [RFC 1/2] dt-bindings: add mmio-based syscon mux controller DT bindings Message-ID: <20170419220900.ndrtt2m7d6tqsddh@rob-hp-laptop> References: <20170413154812.19597-1-p.zabel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170413154812.19597-1-p.zabel@pengutronix.de> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 13, 2017 at 05:48:11PM +0200, Philipp Zabel wrote: > This adds device tree binding documentation for mmio-based syscon > multiplexers controlled by a single bitfield in a syscon register > range. > > Signed-off-by: Philipp Zabel > --- > Documentation/devicetree/bindings/mux/mmio-mux.txt | 56 ++++++++++++++++++++++ > 1 file changed, 56 insertions(+) > create mode 100644 Documentation/devicetree/bindings/mux/mmio-mux.txt > > diff --git a/Documentation/devicetree/bindings/mux/mmio-mux.txt b/Documentation/devicetree/bindings/mux/mmio-mux.txt > new file mode 100644 > index 0000000000000..11d96f5d98583 > --- /dev/null > +++ b/Documentation/devicetree/bindings/mux/mmio-mux.txt > @@ -0,0 +1,56 @@ > +MMIO bitfield-based multiplexer controller bindings > + > +Define a syscon bitfield to be used to control a multiplexer. The parent > +device tree node must be a syscon node to provide register access. > + > +Required properties: > +- compatible : "gpio-mux" ? > +- reg : register base of the register containing the control bitfield > +- bit-mask : bitmask of the control bitfield in the control register > +- bit-shift : bit offset of the control bitfield in the control register > +- #mux-control-cells : <0> > +* Standard mux-controller bindings as decribed in mux-controller.txt > + > +Optional properties: > +- idle-state : if present, the state the mux will have when idle. The > + special state MUX_IDLE_AS_IS is the default. > + > +The multiplexer state is defined as the value of the bitfield described > +by the reg, bit-mask, and bit-shift properties, accessed through the parent > +syscon. > + > +Example: > + > + syscon { > + compatible = "syscon"; > + > + mux: mux-controller@3 { > + compatible = "mmio-mux"; > + reg = <0x3>; > + bit-mask = <0x1>; > + bit-shift = <5>; This pattern doesn't scale once you have multiple fields @ addr 3. I also don't really think a node per register field in DT really scales. I think the parent should be declared as a mux controller instead. You could encode the mux addr and bit position in the mux cells. > + #mux-control-cells = <0>; > + }; > + }; > + > + video-mux { > + compatible = "video-mux"; > + mux-controls = <&mux>; The mux binding was largely defined for a single control controling multiple muxes. This doesn't really fit that, but I guess this is an improvement over a custom syscon phandle. > + > + ports { > + /* input 0 */ > + port@0 { > + reg = <0>; > + }; > + > + /* input 1 */ > + port@1 { > + reg = <1>; > + }; > + > + /* output */ > + port@2 { > + reg = <2>; > + }; > + }; > + }; > -- > 2.11.0 >