From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941122AbcLVPA7 (ORCPT ); Thu, 22 Dec 2016 10:00:59 -0500 Received: from smtprelay.synopsys.com ([198.182.60.111]:54859 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758570AbcLVPA4 (ORCPT ); Thu, 22 Dec 2016 10:00:56 -0500 Subject: Re: [PATCH v4 3/5] i2c: designware: Add slave definitions To: Rob Herring , Luis de Oliveira References: <5173a9456c423025d8f15baafa2499440cbe1b51.1481131072.git.lolivei@synopsys.com> <20161212170214.4cydp256jsp7srar@rob-hp-laptop> CC: "wsa@the-dreams.de" , "mark.rutland@arm.com" , "jarkko.nikula@linux.intel.com" , "andriy.shevchenko@linux.intel.com" , "mika.westerberg@linux.intel.com" , "linux-i2c@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Ramiro.Oliveira@synopsys.com" , "Joao.Pinto@synopsys.com" , "CARLOS.PALMINHA@synopsys.com" From: Luis Oliveira Message-ID: <3ef11852-8dc5-dbb3-7dc3-1ec8f4fc58da@synopsys.com> Date: Thu, 22 Dec 2016 14:59:07 +0000 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.107.25.56] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13-Dec-16 14:11, Rob Herring wrote: > Again, please don't top post. And your line wrapping is messed up. > IOW, you can't use Outlook. > > On Tue, Dec 13, 2016 at 4:50 AM, Luis de Oliveira > wrote: >> The controller for i2c-designware cannot be slave/master at the same time and it has to be enabled knowing beforehand if we want it to be slave or master by something outside of the controller itself. >> >> I as looking and I see the use of this I2C_OWN_SLAVE_ADDRESS with the "linux,slave-24c02" slave interface but I am not seeing how it will help me identify a selected i2c-designware block as a "slave" device before instantiation. I'm sorry if I'm not understanding properly. >> I use the "linux,slave-24c02" to instantiate the i2c-designware as a slave with an address so I can do write/read operations, it is how I tested it. > > Something like this: > > of_for_each_child_node(child) { > of_property_read_u32(child, "reg", ®); > if (reg & I2C_OWN_SLAVE_ADDRESS)) > im_a_slave = true; > } > > ...rather than testing "mode" is equal to "slave". > > Rob > Hi Rob, Andy, I'm struggling to implement your suggestion @Rob. I checked the tegra124-jetson-tk1.dts that uses that approach but I have some doubts. My DT is as follows i2c@0x2000 { compatible = "snps,designware-i2c"; reg = <0x2000 0x100>; clock-frequency = <400000>; clocks = <&i2cclk>; interrupts = <0>; I could add something like this: eeprom@64 { compatible = "linux,slave-24c02"; reg = <(I2C_OWN_SLAVE_ADDRESS | 0x64)>; } But I think this is different form what I was doing before. I have two questions: - This way the I2C controller is identified as a slave controller or just the subnode eeprom? - This way looks like my slave address will be fixed In the previous Patch v3 submission @Andy suggested a property that selects mode that I did and it's working. And you @Rob suggested to do it a common property. It is implemented in the DT like: mode = "slave"; So before I do this changes can you please agree both if you still think this is the best approach? Thank you both for your time, Luis >> >> Luis >> >> -----Original Message----- >> From: Rob Herring [mailto:robh@kernel.org] >> Sent: Monday, December 12, 2016 23:16 >> To: Luis de Oliveira >> Cc: wsa@the-dreams.de; mark.rutland@arm.com; jarkko.nikula@linux.intel.com; andriy.shevchenko@linux.intel.com; mika.westerberg@linux.intel.com; linux-i2c@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Ramiro.Oliveira@synopsys.com; Joao.Pinto@synopsys.com; CARLOS.PALMINHA@synopsys.com >> Subject: Re: [PATCH v4 3/5] i2c: designware: Add slave definitions >> >> On Mon, Dec 12, 2016 at 12:35 PM, Luis de Oliveira wrote: >>> Hi all, >> >> Please don't top post. >> >>> >>> The slave address could be set by the I2C slave backend so I can't use it to setup the controller. >>> A boolean property was my initial approach then Andy and Wolfram Sang suggested the use of compatible strings and later It was suggested to use a property to select mode but I can do it again if it's the best way. >>> Can you please tell me where should it be documented? >> >> bindings/i2c/i2c.txt. >> >> Actually, looking at this some more, we already have a way to describe the controller being a slave device with the I2C_OWN_SLAVE_ADDRESS flag in the reg property. We should just need a helper to read reg property of each child and check for the bit set. >> >> Rob