From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH v2 0/7] Add support for Exynos SROM Controller driver Date: Tue, 06 Oct 2015 09:23:42 +0900 Message-ID: <5613148E.8010903@samsung.com> References: <1440403348-8974-1-git-send-email-pankaj.dubey@samsung.com> <018501d0ff62$1650b410$42f21c30$@samsung.com> <5612719E.60006@samsung.com> <01cb01d0ff70$6027b760$20772620$@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout1.w1.samsung.com ([210.118.77.11]:45815 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbbJFAXs (ORCPT ); Mon, 5 Oct 2015 20:23:48 -0400 In-reply-to: <01cb01d0ff70$6027b760$20772620$@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Pavel Fedin , 'Pankaj Dubey' , linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: k.kozlowski.k@gmail.com, thomas.ab@samsung.com, kgene@kernel.org, heiko@sntech.de On 05.10.2015 22:18, Pavel Fedin wrote: > Hello! > >> That is interesting. What do you mean by that? Although SROM controller >> can access external memory (SRAM, ROM) but it is not exactly a bus. How >> is the SMSC9111 "connected"? What interface or protocol is used? > > SROM controller actually provides a demultiplexed external address and data bus. This way you could > hook up old good ROM chip to it (hence its name). However, you can plug in there anything else with > the appropriate interface, and SMSC9111 uses exactly that. Just some address + control + data wires. > Therefore, you can think of SROMc as a simple bus. Ah, okay, thanks for details. > >> I am sorry but I cannot figure out what exactly are you talking about. >> The Device Tree is the glue to describe the board, the hardware and its >> configuration. Please elaborate a little more. > > Yes, exactly that. SROM controller has 4 outputs, and for every of these outputs you have to choose > mode and timings. Once you set them correctly, you can use peripherial behind them. These timings > actually depend on the actual peripherial. > > By this time i remembered that u-boot guys also did something with this. And here are links: > http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/dts/exynos5250-smdk5250.dts;h=8b695442b1a29dec4e3 > 53ebd3cfee0ff89f218a6;hb=HEAD#l43 - this is how connection is described > http://git.denx.de/?p=u-boot.git;a=blob;f=board/samsung/common/board.c;h=d32c75de50858f131284e28db0c > 7ed55883f1cb0;hb=HEAD#l184 - and this is parsing code I see... Pankaj's driver was not developed for that purpose. You would have to extend it. For the SROMC driver there shouldn't be much work to do: just parse additional bindings and configure the controller for ethernet adapter. > There's only one small problem with their code. "bank" parameter is device-wide, therefore you > cannot configure more than one bank. For SMDK boards it's OK, but in future you may run into problem > with this. You are not bound by u-boot bindings anyhow (at least to my understanding). You can try to re-use them but if some binding is problematic then just create your own. Best regards, Krzysztof From mboxrd@z Thu Jan 1 00:00:00 1970 From: k.kozlowski@samsung.com (Krzysztof Kozlowski) Date: Tue, 06 Oct 2015 09:23:42 +0900 Subject: [PATCH v2 0/7] Add support for Exynos SROM Controller driver In-Reply-To: <01cb01d0ff70$6027b760$20772620$@samsung.com> References: <1440403348-8974-1-git-send-email-pankaj.dubey@samsung.com> <018501d0ff62$1650b410$42f21c30$@samsung.com> <5612719E.60006@samsung.com> <01cb01d0ff70$6027b760$20772620$@samsung.com> Message-ID: <5613148E.8010903@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05.10.2015 22:18, Pavel Fedin wrote: > Hello! > >> That is interesting. What do you mean by that? Although SROM controller >> can access external memory (SRAM, ROM) but it is not exactly a bus. How >> is the SMSC9111 "connected"? What interface or protocol is used? > > SROM controller actually provides a demultiplexed external address and data bus. This way you could > hook up old good ROM chip to it (hence its name). However, you can plug in there anything else with > the appropriate interface, and SMSC9111 uses exactly that. Just some address + control + data wires. > Therefore, you can think of SROMc as a simple bus. Ah, okay, thanks for details. > >> I am sorry but I cannot figure out what exactly are you talking about. >> The Device Tree is the glue to describe the board, the hardware and its >> configuration. Please elaborate a little more. > > Yes, exactly that. SROM controller has 4 outputs, and for every of these outputs you have to choose > mode and timings. Once you set them correctly, you can use peripherial behind them. These timings > actually depend on the actual peripherial. > > By this time i remembered that u-boot guys also did something with this. And here are links: > http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/dts/exynos5250-smdk5250.dts;h=8b695442b1a29dec4e3 > 53ebd3cfee0ff89f218a6;hb=HEAD#l43 - this is how connection is described > http://git.denx.de/?p=u-boot.git;a=blob;f=board/samsung/common/board.c;h=d32c75de50858f131284e28db0c > 7ed55883f1cb0;hb=HEAD#l184 - and this is parsing code I see... Pankaj's driver was not developed for that purpose. You would have to extend it. For the SROMC driver there shouldn't be much work to do: just parse additional bindings and configure the controller for ethernet adapter. > There's only one small problem with their code. "bank" parameter is device-wide, therefore you > cannot configure more than one bank. For SMDK boards it's OK, but in future you may run into problem > with this. You are not bound by u-boot bindings anyhow (at least to my understanding). You can try to re-use them but if some binding is problematic then just create your own. Best regards, Krzysztof