From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v7] mfd: syscon: Decouple syscon interface from platform devices Date: Mon, 6 Oct 2014 17:27:32 +0100 Message-ID: <20141006162732.GB3848@lee--X1> References: <1412066127-27063-1-git-send-email-pankaj.dubey@samsung.com> <004101cfe144$5aa3e570$0febb050$@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-ie0-f173.google.com ([209.85.223.173]:63513 "EHLO mail-ie0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888AbaJFQ1k (ORCPT ); Mon, 6 Oct 2014 12:27:40 -0400 Received: by mail-ie0-f173.google.com with SMTP id tp5so3644575ieb.18 for ; Mon, 06 Oct 2014 09:27:40 -0700 (PDT) Content-Disposition: inline In-Reply-To: <004101cfe144$5aa3e570$0febb050$@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Pankaj Dubey Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 'linux-samsung-soc' , 'Arnd Bergmann' , b29396@freescale.com, boris.brezillon@free-electrons.com, 'Tomasz Figa' , 'Russell King' , 'VIKAS SAJJAN C' , naushad@samsung.com, 'Thomas P Abraham' , 'Kukjin Kim' , Li.Xiubo@freescale.com, geert+renesas@glider.be, 'Stephen Warren' , 'Doug Anderson' On Mon, 06 Oct 2014, Pankaj Dubey wrote: > Hi Lee, >=20 > On Tuesday, September 30, 2014 9:39 PM Doug Anderson wrote, > > Subject: Re: [PATCH v7] mfd: syscon: Decouple syscon interface from= platform > > devices > >=20 > > Pankaj, > >=20 > > On Tue, Sep 30, 2014 at 1:35 AM, Pankaj Dubey > > wrote: > > > Currently a syscon entity can be only registered directly through= a > > > platform device that binds to a dedicated syscon driver. However = in > > > certain use cases it is desirable to make a device used with anot= her > > > driver a syscon interface provider. > > > > > > For example, certain SoCs (e.g. Exynos) contain system controller > > > blocks which perform various functions such as power domain contr= ol, > > > CPU power management, low power mode control, but in addition con= tain > > > certain IP integration glue, such as various signal masks, coproc= essor > > > power control, etc. In such case, there is a need to have a dedic= ated > > > driver for such system controller but also share registers with o= ther > > > drivers. The latter is where the syscon interface is helpful. > > > > > > In case of DT based platforms, this patch decouples syscon object= from > > > syscon platform driver, and allows to create syscon objects first= time > > > when it is required by calling of syscon_regmap_lookup_by APIs an= d > > > keep a list of such syscon objects along with syscon provider > > > device_nodes and regmap handles. > > > > > > For non-DT based platforms, this patch keeps syscon platform driv= er > > > structure so that syscon can be probed and such non-DT based driv= ers > > > can use syscon_regmap_lookup_by_pdev API and access regmap handle= s. > > > Once all users of "syscon_regmap_lookup_by_pdev" migrated to DT b= ased, > > > we can completely remove platform driver of syscon, and keep only > > > helper functions to get regmap handles. > > > > > > Suggested-by: Arnd Bergmann > > > Suggested-by: Tomasz Figa > > > Tested-by: Vivek Gautam > > > Tested-by: Javier Martinez Canillas > > > Signed-off-by: Pankaj Dubey > > > Reviewed-by: Arnd Bergmann > > > Tested-by: Heiko Stuebner > > > Reviewed-by: Heiko Stuebner > > > --- > > > Patch v6 and related discussions can be found here [1]. > > > > > > Change since v5: > > > - Addressed review comments from "Heiko Stuebner". > > > - Updated commit description. > > > - Including Arnd's and Heiko's Reviewed-by. > > > > > > Change since v5: > > > - Dropping creation of dummy platform device in of_syscon_regist= er. > > > - As we are changing syscon to decouple from platform_device, cr= eation of > > > dummy platform_device does not look good option, and as sugges= ted by Arnd, > > > I made another attempt so that regmap_mmio_init API should wor= k with NULL > > > dev pointer itself. Since regmap needs to know about Syscon de= vice node > > > properties so let's parse device node of syscon in syscon itse= lf for any > > > such properties and using regmap_config parameter pass all suc= h information > > > to regmap. Other concern of crashes due to NULL dev pointer in= regmap already > > > addressed in separate patches of regmap. Please see [2] and [3= ]. > > > > > > Changes since v4: > > > - Addressed Tomasz Figa's comments for v4. > > > - Added error handing in of_syscon_register function. > > > - Using devm_regmap_init_mmio instead of regmap_init_mmio. > > > > > > Changes since v3: > > > - Addressed Arnd's comment for v2. > > > - Updated of_syscon_register for adding dev pointer in regmap_in= it_mmio. > > > - For early users created dummy platform device. > > > > > > Changes since v2: > > > - Added back platform device support from syscon, with one chang= e that > > > syscon will not be probed for DT based platform. > > > - Added back syscon_regmap_lookup_by_pdevname API so that non-DT= base > > > users of syscon will not be broken. > > > - Removed unwanted change in syscon.h. > > > - Modified Signed-off-by list, added Suggested-by of Tomasz Figa= and > > > Arnd Bergmann. > > > - Added Tested-by of Vivek Gautam for testing on Exynos platform= =2E > > > > > > Changes since v1: > > > - Removed of_syscon_unregister function. > > > - Modified of_syscon_register function and it will be used by sy= scon.c > > > to create syscon objects whenever required. > > > - Removed platform device support from syscon. > > > - Removed syscon_regmap_lookup_by_pdevname API support. > > > - As there are significant changes w.r.t patchset v1, I am takin= g over > > > author for this patchset from Tomasz Figa. > > > > > > [1]: https://lkml.org/lkml/2014/9/29/99 > > > [2]: https://lkml.org/lkml/2014/9/18/130 > > > [3]: https://lkml.org/lkml/2014/9/27/2 > > > drivers/mfd/syscon.c | 96 > > ++++++++++++++++++++++++++++++++++++++------------ > > > 1 file changed, 74 insertions(+), 22 deletions(-) > >=20 > > You probably already have enough tags, but just in case. ;) On an= rk3288-based > > system (this patch backported to 3.14): > >=20 > > Tested-by: Doug Anderson >=20 > I think now we can take have this patch in. So will you please take t= his patch. I plan to take this when the merge window has closed. --=20 Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog