From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757341AbbIUTZA (ORCPT ); Mon, 21 Sep 2015 15:25:00 -0400 Received: from mail-wi0-f193.google.com ([209.85.212.193]:35316 "EHLO mail-wi0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752891AbbIUTY5 (ORCPT ); Mon, 21 Sep 2015 15:24:57 -0400 MIME-Version: 1.0 In-Reply-To: References: <1442615803-17766-1-git-send-email-const@MakeLinux.com> Date: Mon, 21 Sep 2015 22:24:56 +0300 X-Google-Sender-Auth: xqs2HHuM6MaO2tmY7sRdM3Wi_tI Message-ID: Subject: Re: Please suggest proper format for DT properties. From: Constantine Shulyupin To: Rob Herring Cc: open list , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , lm-sensors@lm-sensors.org, Jean Delvare , Guenter Roeck , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 21, 2015 at 4:51 AM, Rob Herring wrote: > On Fri, Sep 18, 2015 at 5:36 PM, Constantine Shulyupin > wrote: >> Hi, >> >> I am designing DT support for a hwmon chip. >> It has some sensors, each of them can be: >> - "disabled" >> - "thermal diode" >> - "thermistor" >> - "voltage" >> >> Four possible options for DT properties format. >> >> Option 1: Separated property for each sensor. >> >> Example nct7802 node: >> >> nct7802 { >> compatible = "nuvoton,nct7802"; >> reg = <0x2a>; >> nuvoton,sensor1-type = "thermistor"; >> nuvoton,sensor2-type = "disabled"; >> nuvoton,sensor3-type = "voltage"; >> }; >> >> Option 2: Array of strings for all sensors. >> >> nct7802 { >> compatible = "nuvoton,nct7802"; >> reg = <0x2a>; >> nuvoton,sensors-types = "thermistor", "disabled", "voltage"; >> }; > > It seems you are just listing out all possible modes. Why do you need > this in the DT at all? This can be inferred by the compatible string. There are tree sensor, each of one can be one of three type ("thermal diode", "thermistor", "voltage") or be disabled. Also there are at least five platform depended registers, most of them are enable/disable. You can find full datasheet here https://www.nuvoton.com/hq/products/cloud-computing/hardware-monitors/desktop-server-series/nct7802y/ The question is how to describe configuration of this registers in dts. The second option is array of types for tree registers. >> Option 3: Sets of 4 cells. >> >> Borrowed from marvell,reg-init and broadcom,c45-reg-init. >> >> The first cell is the page address, >> the second a register address within the page, >> the third cell contains a mask to be ANDed with the existing register >> value, and the fourth cell is ORed with the result to yield the >> new register value. If the third cell has a value of zero, >> no read of the existing value is performed. > > I don't see how this relates to the first 2 options. The register you > write selects the mode? In general, we don't want bindings of just > random register writes. > > Rob Option 3 allows arbitrary registers configuration. To see the full picture you can refer to datasheet mentioned above to function nct7802_init_chip via http://lxr.free-electrons.com/source/drivers/hwmon/nct7802.c#L789 and proposed patch for option #2: https://lkml.org/lkml/2015/9/13/204 -- Thanks Constantine