From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756082AbdDRITX (ORCPT ); Tue, 18 Apr 2017 04:19:23 -0400 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:37089 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755614AbdDRITK (ORCPT ); Tue, 18 Apr 2017 04:19:10 -0400 Message-ID: <1492503544.2432.32.camel@pengutronix.de> Subject: Re: [RFC 1/2] dt-bindings: add mmio-based syscon mux controller DT bindings From: Philipp Zabel To: Peter Rosin , Pavel Machek Cc: Rob Herring , Mark Rutland , Sakari Ailus , Steve Longerbeam , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de Date: Tue, 18 Apr 2017 10:19:04 +0200 In-Reply-To: <20170413154812.19597-1-p.zabel@pengutronix.de> References: <20170413154812.19597-1-p.zabel@pengutronix.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1+b1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2017-04-13 at 17:48 +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>; > + #mux-control-cells = <0>; > + }; > + }; > + > + video-mux { > + compatible = "video-mux"; > + mux-controls = <&mux>; > + > + ports { > + /* input 0 */ > + port@0 { > + reg = <0>; > + }; > + > + /* input 1 */ > + port@1 { > + reg = <1>; > + }; > + > + /* output */ > + port@2 { > + reg = <2>; > + }; > + }; > + }; So Pavel (added to Cc:) suggested to merge these into one node for the video mux, as really we are describing a single hardware entity that happens to be multiplexing multiple video buses into one: syscon { compatible = "syscon"; /* video multiplexer */ mux: mux-controller@3 { compatible = "video-mmio-mux"; reg = <0x3>; bit-mask = <0x1>; bit-shift = <5>; #mux-control-cells = <0>; mux-controls = <&mux>; ports { /* input 0 */ port@0 { reg = <0>; }; /* input 1 */ port@1 { reg = <1>; }; /* output */ port@2 { reg = <2>; }; }; }; }; That would not touch on this "general purpose" mmio-mux binding itself, but would make it necessary to add a separate "video-mmio-mux" and a "video-gpio-mux" binding that mirror the "mmio-mux" and "gpio-mux" bindings but add the OF-graph connections. Also I think in this case the self-referencing mux-controls property would be superfluous, as the driver binding to this node is expected to control the mux according to activation of the links described by the OF-graph bindings. regards Philipp